- Direct synthesis of dimethyl carbonate from methanol and carbon dioxide over Ga2O3/Ce0.6Zr0.4O2 catalysts: Effect of acidity and basicity of the catalysts
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Ce X Zr1-X O2 catalysts with different cerium content (X) (X = 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1.0) were prepared by a sol-gel method for use in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Among these catalysts, Ce0.6Zr 0.4O2 was found to show the best catalytic performance. In order to enhance the acidity and basicity of Ce0.6Zr 0.4O2 catalyst, Ga2O3 was supported on Ce0.6Zr0.4O2 (XGa2O 3/Ce0.6Zr0.4O2 (X = 1, 5, 10, and 15)) by an incipient wetness impregnation method with a variation of Ga 2O3 content (X, wt%). Effect of acidity and basicity of Ga2O3/Ce0.6Zr0.4O2 on the catalytic performance in the direct synthesis of dimethyl carbonate was investigated using NH3-TPD and CO2-TPD experiments. Experimental results revealed that both acidity and basicity of the catalysts played a key role in determining the catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Large acidity and basicity of the catalyst facilitated the formation of dimethyl carbonate. The amount of dimethyl carbonate produced over XGa2O 3/Ce0.6Zr0.4O2 catalysts increased with increasing both acidity and basicity of the catalysts. Among the catalysts tested, 5Ga2O3/Ce0.6Zr0.4O 2, which retained the largest acidity and basicity, showed the best catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Graphical Abstract: In the direct synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide over Ga 2O3/Ce0.6Zr0.4O2 catalysts, the amount of DMC showed a volcano-shaped curve with respect to Ga2O3 content. The amount of DMC increased with increasing both acidity and basicity of the catalysts [Figure not available: see fulltext.]
- Lee, Hye Jin,Park, Sunyoung,Song, In Kyu,Jung, Ji Chul
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- Efficient fixation and conversion of CO2 into dimethyl carbonate catalyzed by an imidazolium containing tri-cationic ionic liquid/super base system
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The synthesis route used to prepare dimethyl carbonate from CO2 and methanol is a most attractive route from a green chemistry point of view. Herein, we systematically studied binary catalyst systems for the synthesis of dimethyl carbonate from CO2 and methanol. It was found that [GLY(mim)3][NTf2]3IL/DBU, [GLY(mim)3][NTf2]3/MTBD and [GLY(mim)3][NTf2]3/TBD are effective binary catalysts for the direct synthesis of DMC without the need of a dehydration system. In particular, the [GLY(mim)3][NTf2]3 IL/1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) system was found to have 37% MeOH conversion and 93% DMC selectivity under mild reaction conditions. However, the tri-imidazolium salts were compatible with DBU for effective CO2 adsorption, possibly because of the reactive C(2)-H in the imidazolium ring. Furthermore, the [GLY(mim)3][NTf2]3 IL/DBU catalytic system could be easily recovered and reused three times without any obvious loss of catalytic activity. The catalytic reactivity of [GLY(mim)3][NTf2]3 IL/DBU for the synthesis of DMC was proved by its predictable mechanism on the basis of 13C NMR spectroscopy.
- Chaugule, Avinash A.,Tamboli, Ashif H.,Kim, Hern
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- Triorganotin(iv) cation-promoted dimethyl carbonate synthesis from CO2 and methanol: Solution and solid-state characterization of an unexpected diorganotin(iv)-oxo cluster
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Two novel C,N-chelated organotin(iv) complexes bearing weakly coordinating carborane moieties were prepared by the reaction of the corresponding C,N-chelated organotin(iv) chloride (i.e. LCNR2SnCl, R = n-Bu (1) and Ph (2); LCN = 2-(N,N-dimethylaminomethyl)phenyl)) with monocarba-closo-dodecaborate silver salt (AgCB11H12; Ag·3). Both products of the metathesis, [LCN(n-Bu)2Sn]+[CB11H12]- (4) and [LCNPh2Sn]+ [CB11H12]- (5), respectively, were characterized by both multinuclear NMR spectroscopy and elemental analysis. The instability of 4 and 5 towards water is discussed. The solid-state structure of LCN(n-Bu)2SnOH·B(C6F5)3 (4a) as a model compound with a Sn-O(H)?B linkage is also reported. The evaluation of the catalytic activity of 4 and 5 was carried out within the direct synthesis of dimethyl carbonate (DMC) from methanol and CO2. While 5 was shown to be definitively inactive, presumably due to cleavage of the Sn-Ph bond, compound 4 exhibits a beneficial action, since it leads to an amount of DMC higher than the stoichiometry (nDMC/nSn(cat) = 1.5). In addition, the solid state structures of [BnNMe3]+[CB11H12]- (6) and [(n-Bu)20Sn10O2(OMe)6(CO3)2]2+·2[CB11H12]- (7), isolated as single-crystals and resulting from the recombination of 4 under the reaction conditions (methanol/CO2), were established by sc-XRD analyses within the term of this work as well. 6 and 7 were also fully characterized by IR spectroscopy, multinuclear NMR in solution and elemental analysis.
- ?vec, Petr,Cattey, Hélène,R??i?ková, Zdeňka,Holub, Josef,R??i?ka, Ale?,Plasseraud, Laurent
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- Zn/Fe mixed oxide: Heterogeneous catalyst for the synthesis of dimethyl carbonate from methyl carbamate and methanol
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A series of Zn-Fe-O mixed oxides were prepared for the synthesis of dimethyl carbonate (DMC) from methyl carbamate and methanol. X-ray diffraction revealed that zinc ferrite crystal phase appeared and changed with different Zn/Fe molar ratio. The DMC yield could reach 30.7% under suitable conditions. In addition, elemental chemical analysis and the reusability test indicated that these catalysts presented good stability.
- Wang, Dengfeng,Zhang, Xuelan,Gao, Yangyan,Xiao, Fukui,Wei, Wei,Sun, Yuhan
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- Graphene oxide supported molybdenum cluster: First heterogenized homogeneous catalyst for the synthesis of dimethylcarbonate from CO2and methanol
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The octahedral molybdenum cluster-based compound, Cs2Mo6Bri8Bra6 was immobilized on graphene oxide (GO) by using a facile approach. High resolution transmission electron microscopy results revealed that molybdenum clusters were uniformly distributed on the GO nanosheets. Cs2Mo6Bri8Bra6 was attached to the GO support via chemical interaction between apical ligands of Mo6Bri8Bra6 cluster units and oxygen functionalities of GO, as revealed by XPS studies. The developed material was used for the synthesis of dimethyl carbonate by reduction of carbon dioxide. The synthesized catalyst, that is, GO-Cs2Mo6Bri8Brax, exhibited higher catalytic efficiency than its homogeneous analogue without using dehydrating agent. The catalyst was found to be efficiently recyclable without significant loss of catalytic activity.
- Kumar, Subodh,Khatri, Om P.,Cordier, St??phane,Boukherroub, Rabah,Jain, Suman L.
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- Preparation and characterization of H3PW12O40/ZrO2 catalyst for carbonation of methanol into dimethyl carbonate
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A H3PW12O40/ZrO2 catalyst for effective dimethyl carbonate (DMC) formation via methanol carbonation was prepared using the sol–gel method. X-ray photoelectron spectra showed that reactive and dominant (63%) W(VI) species, in WO3 or H2WO4, enhanced the catalytic performances of the supported ZrO2. The mesoporous structure of H3PW12O40/ZrO2 was identified by nitrogen adsorption–desorption isotherms. In particular, partial sintering of catalyst particles in the duration of methanol carbonation caused a decrease in the Brunauer–Emmett–Teller surface area of the catalyst from 39 to 19?m2/g. The strong acidity of H3PW12O40/ZrO2 was confirmed by the desorption peak observed at 415?°C in NH3 temperature-programmed desorption curve. At various reaction temperatures (T = 110, 170, and 220?°C) and CO2/N2 volumetric flow rate ratios (CO2/N2 = 1/4, 1/7, and 1/9), the calculated catalytic performances showed that the optimal methanol conversion, DMC selectivity, and DMC yield were 4.45, 89.93, and 4.00%, respectively, when T = 170?°C and CO2/N2 = 1/7. Furthermore, linear regression of the pseudo-first-order model and Arrhenius equation deduced the optimal rate constant (4.24 × 10?3?min?1) and activation energy (Ea = 15.54?kJ/mol) at 170?°C with CO2/N2 = 1/7 which were favorable for DMC formation.
- Chiang, Chao Lung,Lin, Kuen Song,Yu, Ssu-Han
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- Synthesis of dimethyl carbonate from methyl carbamate and methanol catalyzed by mixed oxides from hydrotalcite-like compounds
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A series of mixed oxides calcined from hydrotalcite-like compounds with different cations were prepared and their catalytic activities were studied by the synthesis of dimethyl carbonate (DMC) from methyl carbamate and methanol. Among them, ZnFe mixed oxide possessed the best catalytic ability. Furthermore, the zinc-based mixed oxides as well as the corresponding hydrotalcite-like compounds were characterized by using ICP, TGA, CO2-TPD and N2 adsorption/desorption techniques.
- Wang, Dengfeng,Zhang, Xuelan,Zhao, Wenbo,Peng, Weicai,Zhao, Ning,Xiao, Fukui,Wei, Wei,Sun, Yuhan
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- Reaction of dibutyltin oxide with methanol under CO2 pressure relevant to catalytic dimethyl carbonate synthesis
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Dibutyltin oxide (Bu2SnO)n (3) reacts with methanol to give the tetrabutyl(dimethoxy)stannoxane dimer (4). The presence of 2,2-dimethoxypropane under a CO2 pressure accelerates the reaction resulting in nearly quantitative yield. Complex 4 exhibits catalytic activity as high as that of {Bu2Sn(OMe)2}2 (1) in the dimethyl carbonate (DMC) synthesis from CO2 and methanol. These results indicate that the conversion of 3 to 4 occurs under catalytic DMC production conditions.
- Kohno, Kazufumi,Choi, Jun-Chul,Ohshima, Yoshihiro,Yili, Abulimiti,Yasuda, Hiroyuki,Sakakura, Toshiyasu
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- Effects of Mo promoters on the Cu-Fe bimetal catalysts for the DMC formation from CO2 and methanol
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The Mo-promoted Cu-Fe bimetal catalysts were prepared and used for the formation of dimethyl carbonate (DMC) from CO2 and methanol. The catalysts were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), laser Raman spectra (LRS), energy dispersive spectroscopy (EDS) and temperature programmed desorption (TPD) techniques. The experimental results demonstrated that the Mo promoters can decrease the reducibility and increase the dispersion of Cu-Fe clusters. The concentration balance of base-acid sites can be readily adjusted by changing the Mo content. The moderate concentration balance of acid and base sites was in favor of the DMC formation. Under optimal experimental conditions, the highest methanol conversion of 6.99% with a DMC selectivity of 87.7% can be obtained when 2.5 wt% of Mo was loaded.
- Zhou, Ying-Jie,Xiao, Min,Wang, Shuan-Jin,Han, Dong-Mei,Lu, Yi-Xin,Meng, Yue-Zhong
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- Graphene oxide immobilized copper phthalocyanine tetrasulphonamide: The first heterogenized homogeneous catalyst for dimethylcarbonate synthesis from CO2 and methanol
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The first successful synthesis of DMC directly from methanol and carbon dioxide using a heterogenized homogeneous graphene oxide immobilized copper phthalocyanine tetrasulphonamide catalyst in the presence of N,N′-dicyclohexylcarbodiimide (DCC) as a dehydrating agent is described. The presence of a dehydrating agent was found to be vital and in its absence the yield of DMC was found to be decreased significantly. Under the optimized reaction conditions, the maximum yield of DMC reaches up to 13.3%. Although the homogeneous copper phthalocyanine tetrasulphonamide catalyst provided a little higher yield of DMC (14.2%), the facile recovery and recycling ability of the heterogeneous catalyst make the developed method more attractive from environmental and economical viewpoints.
- Kumar, Subodh,Kumar, Pawan,Jain, Suman L.
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- Synthesis of dimethyl carbonate from ethylene carbonate and methanol over nano-catalysts supported on CeO2-MgO
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A series of CeO2(X)-MgO(1-X) (X = 0, 0.25, 0.5, 0.75, and 1.0) nano-catalysts were prepared by a co-precipitation method for use in the synthesis of dimethyl carbonate from ethylene carbonate and methanol. Among the CeO2(X)-MgO(1-X) catalysts, CeO2(0.25)-MgO(0.75) nano-catalyst showed the best catalytic performance. Alkali and alkaline earth metal oxides (MO = Li2O, K2O, Cs2O, SrO, and BaO) were then supported on CeO2(0.25)-MgO(0.75) by an incipient wetness impregnation method with an aim of improving the catalytic performance of CeO2(0.25)-MgO(0.75). Basicity of the catalysts was determined by CO2-TPD experiments in order to elucidate the effect of basicity on the catalytic performance. The correlation between catalytic performance and basicity showed that basicity played an important role in the reaction. Yield for dimethyl carbonate increased with increasing basicity of the catalysts. Among the catalysts tested, Li2O/CeO2(0.25)-MgO(0.75) nano-catalyst with the largest basicity showed the best catalytic performance in the synthesis of dimethyl carbonate.
- Jun, Jin Oh,Lee, Joongwon,Kang, Ki Hyuk,Song, In Kyu
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- Gas-phase oxycarbonylation of methanol for the synthesis of dimethyl carbonate using copper-based Supported Ionic Liquid Phase (SILP) catalysts
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Catalyst systems for the gas-phase oxycarbonylation of methanol often suffer from low catalyst activities and strong catalyst deactivation. In this work, the continuous gas-phase oxycarbonylation of methanol was realized by using Supported Ionic Liquid-Phase (SILP) catalysts. Copper(I) bromide dissolved in various ionic liquids and dispersed on Polymer-Based Spherical Activated Carbon (PBSAC) as supporting material was found to be an active catalyst. The poor activity and stability of copper halide catalysts reported in literature was substantially increased by the presence of ionic liquids. In particular, trioctylmethylammonium bromide in combination with a basic salt additive increased the activity of the CuBr catalyst and led to comparatively stable SILP catalyst operation reaching a total turnover number of 600 over 50 h time-on-stream.
- Schneider, Martin Johannes,Haumann, Marco,Stricker, Marion,Sundermeyer, Joerg,Wasserscheid, Peter
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- The influence of halogen anions and N-ligands in CuXn/N-ligands on the catalytic performance in oxidative carbonylation of methanol
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The catalytic properties of CuXn/N-ligands (X=Cl, Br and I; n = 1 or 2) in oxidative carbonylation ofmethanolwere investigated. It was found that the interaction of halogen anions, N-ligands and Cu (I) affected the catalytic performance of copper complex catalyst in the reaction, especially iodide anion and 1,10-phenanthroline (Phen). When CuI/Phen was used as a catalyst, the conversion of methanol was 42.6%, the selectivity to dimethyl carbonate was 99.2% and the TOF was 13.1 h-1 at an optimized conditions: CuI/Phen 0.2 mol l-1, 120 °C, 2 h, 2.4 MPa, PCO/PO2 = 2:1. Compared with the plain CuI catalyst, the catalytic activity of CuI/Phen increased about 36 times.When CuI/Phen catalystwas immobilized on polystyrene (PS), the heterogenized catalyst,CuI/Phen-NH-PS, also exhibited veryhigh catalytic activity in oxidative carbonylation. The CuI/Phen - NH - PS catalyst remained its high catalytic activity even after seven recycles. The average weight loss of CuI/Phen - NH - PS after reaction was less than 1.0%, and the leaching of copper was only about 0.15% in each recycling test. Copyright
- Mo, Wanling,Xiong, Hui,Hu, Jianglin,Ni, Youming,Li, Guangxing
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- A new redox strategy for low-temperature formation of strong basicity on mesoporous silica
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A redox strategy was designed to generate strong basicity on mesoporous silica by using the redox interaction of a precursor with methanol vapor. The formation of strongly basic sites was realized at 400 °C, which breaks the tradition of thermally induced decomposition that usually requires much higher temperatures (>600 °C).
- Zhu, Li,Lu, Feng,Liu, Xiao-Dan,Liu, Xiao-Qin,Sun, Lin-Bing
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- Efficient ceria-zirconium oxide catalyst for carbon dioxide conversions: Characterization, catalytic activity and thermodynamic study
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In this study, ceria-zirconia based catalysts (CeO2, ZrO2and Ce0.5Zr0.5O2) were synthesized by hydrothermal method and characterized by N2-sorption, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Acidity and basicity of synthesized catalysts were investigated by NH3[sbnd] and CO2[sbnd] temperature-programmed desorption (TPD). Brunauer-Emmett-Teller (BET) surface area of CeO2, Ce0.5Zr0.5O2and ZrO2were found to be 88, 117 and 70?m2?g?1and average crystallite sizes was 9.48, 7.09 and 9.45?nm, respectively. These catalysts were further used for direct conversion of CO2with methanol for the synthesis of dimethyl carbonate (DMC). DMC yield was found to be highly dependent upon the both basicity and acidity of catalysts. Ce0.5Zr0.5O2catalysts showed better activity as compared to CeO2and ZrO2catalysts. Effect of reaction conditions (such as catalyst dose, reaction temperature and reaction time) and catalyst reusability was studied with Ce0.5Zr0.5O2catalyst. The optimum operating condition for direct conversion of CO2into DMC at constant pressure of 150 bar were found to be reaction time?=?24?h, catalyst dose?=?1.25?g and temperature?=?120?°C. Moreover, chemical equilibrium modeling was performed using Peng–Robinson–Stryjek–Vera equation of state (PRSV-EoS) along with the van der Waals one-fluid (1PVDW) mixing rule to calculate the heat of reaction and Gibbs free energy change.
- Kumar, Praveen,With, Patrick,Srivastava, Vimal Chandra,Gl?ser, Roger,Mishra, Indra Mani
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- On the existence of the elusive monomethyl ester of carbonic acid [CH 3OC(O)OH] at 300 K: 1H- and 13C NMR measurements and DFT calculations
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The elusive monomethyl ester of carbonic acid [CH3OC(O)-OH] has been prepared at 300 K by protonation of the sodium salt NaOC(O)OCH3 with anhydrous HCl or water and characterized by 1H- and 13C NMR spectroscopy. The stability of the acid and its reactivity towards hydroxo ions and methylating agents under ambient conditions are discussed. The energetics and the mechanism of the investigated reactions are examined on the basis of density functional calculations. For kinetic and thermodynamic reasons CH3OC(O)OH is unlikely to be formed by insertion of CO2 into the O-H bond of methanol. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Dibenedetto, Angela,Aresta, Michele,Giannoccaro, Potenzo,Pastore, Carlo,Papai, Imre,Schubert, Gabor
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- Carbon dioxide conversion to dimethyl carbonate: The effect of silica as support for SnO2 and ZrO2 catalysts
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Abundant in nature, CO2 poses few health hazards and consequently is a promising alternative to phosgene feedstock according with the principles of Green Chemistry and Engineering. The synthesis organic carbonates from CO2 instead of phosgene is highly challenging as CO2 is much less reactive. As part of our ongoing research on the investigation of catalysts for dimethyl carbonate (DMC) synthesis from methanol and CO 2, we herein report results aimed at comparing the catalytic behavior of new SnO2-based catalysts with that of ZrO2. Silica-supported SnO2 and ZrO2 exhibit turnover numbers which are an order of magnitude higher than those of the unsupported oxides. Tin-based catalysts also promote methanol dehydration which makes them less selective than the zirconium analogues. Last but not least, comparison with soluble Bu2Sn(OCH3)2 highlights the superiority of the organometallic precursor for achieving 100% selectivity to DMC but it deactivates by intermolecular rearrangement into polynuclear tin species.
- Ballivet-Tkatchenko, Danielle,Dos Santos, Jo?o H.Z.,Philippot, Karine,Vasireddy, Sivakumar
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- Fixation of CO2by electrocatalytic reduction to synthesis of dimethyl carbonate in ionic liquid using effective silver-coated nanoporous copper composites
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With high surface area, open porosity and high efficiency, a catalyst was prepared and firstly employed in electrocatalytic reduction of CO2 and electrosynthesis of dimethyl carbonate (DMC). The electrochemical property for electrocatalytic reduction of CO2 in ionic liquid was studied by cyclic voltammogram (CV). The effects of various reaction variables like temperature, working potential and cathode materials on the electrocatalytic performance were also investigated. 80% yield of DMC was obtained under the optimal reaction conditions.
- Wang, Xuan Yun,Liu, Su Qin,Huang, Ke Long,Feng, Qiu Ju,Ye, De Lai,Liu, Bing,Liu, Jin Long,Jin, Guan Hua
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- Dimethyl carbonate production via the oxidative carbonylation of methanol over Cu/SiO2 catalysts prepared via molecular precursor grafting and chemical vapor deposition approaches
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The influence of catalyst synthesis method and Cu source on the activity and selectivity of Cu/SiO2 catalysts for the gas-phase oxidative carbonylation of methanol to dimethyl carbonate (DMC) is reported. [CuOSi(O tBu)3]4, [CuO tBu]4, and CuCl were used as precursors to produce highly dispersed silica-supported copper. XANES and EXAFS characterization prior to reaction (but after thermal treatment under He) showed that Cu in the catalysts prepared with CuCl and [CuOSi(O tBu)3]4 was present primarily as isolated Cu(I) species, whereas [CuO tBu]4 produced 1-nm Cu particles. During the catalytic reaction, the Cu in catalysts prepared from CuCl and [CuOSi(O tBu)3]4 formed highly dispersed CuO moieties, whereas the Cu in catalysts prepared from [CuO tBu]4 formed a cuprous oxide layer over a Cu(0) core. For comparison, poorly dispersed Cu on silica was prepared via traditional incipient wetness impregnation with Cu(NO3)2. It was found that activity for DMC formation increased with increasing Cu dispersion. The selectivity for DMC formation (relative to CO) decreased with decreasing Cu dispersion when the original state of the Cu was Cu(0) directly preceding reaction conditions.
- Drake, Ian J.,Fujdala, Kyle L.,Bell, Alexis T.,Tilley, T. Don
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- Transesterification of cyclic carbonates to dimethyl carbonate using solid oxide catalyst at ambient conditions: Environmentally benign synthesis
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Continuous synthesis at ambient conditions: Dimethyl carbonate (DMC) is an important methylating and carbonylating agent. Transesterification of cyclic carbonates using methanol for the synthesis of DMC is environmentally benign. CaO-ZnO catalysts, prepared by a wet impregnation method, are effective catalysts for the transesterification of ethylene carbonate using methanol in batch and in continuous reactors. Yields of ca. 84?% DMC can be achieved at ambient conditions.
- Sankar, Meenakshisundaram,Satav, Srikanth,Manikandan, Palanichamy
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- Synthesis of dimethyl carbonate from propylene carbonate and methanol over Y2O3/CeO2-La2O3 catalysts
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A series of CeO2(1 - X)-La2O3(X) (X = 0, 0.05, 0.1, 0.15, and 0.2) mixed metal oxide catalysts with different La2O3 molar ratio (X) were prepared by a citric acid-assisted sol-gel method. The catalysts were applied to the synthesis of dimethyl carbonate (DMC) via transesterification of propylene carbonate with methanol. Among these catalysts, it was found that CeO2(0.85)-La2O3(0.15) catalyst showed the highest DMC yield. To improve the catalytic performance of CeO2(0.85)-La2O3(0.15), different amount of Y2O3 was introduced onto CeO2(0.85)-La2O3(0.15) by an incipient wetness impregnation method. The prepared XY2O3/CeO2(0.85)-La2O3(0.15) (X = 0, 3, 6, 9, 12, and 15 wt%) catalysts were then applied to the synthesis of DMC from propylene carbonate and methanol. Basicity of the catalysts was measured by CO2-TPD (temperature-programmed desorption) experiments to investigate the effect of basicity on the catalytic performance. A correlation between basicity and catalytic performance demonstrated that basicity of the catalyst played an important role in the transesterification of propylene carbonate with methanol. Yield for DMC increased with increasing basicity of the catalyst. Among the catalysts tested, 9Y2O3/CeO2(0.85)-La2O3(0.15) catalyst with the largest basicity showed the highest DMC yield.
- Song, Ji Hwan,Jun, Jin Oh,Kang, Ki Hyuk,Han, Seung Ju,Yoo, Jaekyeong,Park, Seungwon,Kim, Do Heui,Song, In Kyu
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- A remarkable effect of alkali addition in the oxidative carbonylation of methanol to dimethyl carbonate catalyzed by a polymer-complexed Cu(II) catalyst system
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The presence of a small amount of alkali additive in the polymer-complexed copper catalysts can lead to a remarkable increase in the reaction efficiency for the oxidative carbonylation of methanol to dimethyl carbonate.
- Feng, Wei-Liang,Cao, Yong,Yi, Nan,Dai, Wei-Lin,Fan, Kang-Nian
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- Oxidative carbonylation of methanol to dimethyl carbonate (DMC): a new catalytic system
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Oxidative carbonylation of methanol to dimethylcarbonate catalysed by cobalt complexes is reported.Cobalt complexes with oxygen and or nitrogen donor ligands such as carboxylate, acetylacetonate, picolinate and Schiff bases are suitable catalysts.The oxidative carbonylation of methanol catalysed by cobalt complexes which has never been reported, affords dimethylcarbonate with remarkably high selectivities.Of the cobalt complexes, those with Schiff bases show the highest reactivity.The influence of co-solvents was also examined.Keywords: Cobalt; Carbonylation; Methanol; Catalysis; Dimethyl carbonate
- Delledonne, Daniele,Rivetti, Franco,Romano, Ugo
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- Structure of the active sites on H3Po4/ZrO2 catalysts for dimethyl carbonate synthesis from methanol and carbon dioxide
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The catalytic properties of H3PO4/ZrO2 catalysts for dimethyl carbonate (DMC) synthesis from CH3OH and CO2 were investigated. The modification of ZrO2 with H3PO4 promoted the activity for selective DMC formation. The characterization of H3PO4/ZrO2 catalysts was performed by means of BET, XRD, 31P MAS NMR, LRS, DRIFT, and NH3-TPD. From the characterization results, it was determined that ZrO2 had Lewis acid sites and did not have Br??nsted acid sites. The presence of Br??nsted acid sites as well as Lewis acid sites was observed on H3PO4/ZrO2 (P/Zr = 0.05). The acidity of the Br??nsted sites is weak, and the site's structure is a bridged OH. Furthermore, this Br??nsted site is formed by the interaction between tetragonal Zr and P. In the reaction scheme of DMC formation, the Br??nsted acid site can contribute to CH3OH activation and to the enhancement of the catalytic activity.
- Ikeda, Yoshiki,Asadullah, Mohammad,Fujimoto, Kaoru,Tomishige, Keiichi
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- Graphene supported Cu nanoparticles as catalysts for the synthesis of dimethyl carbonate: Effect of carbon black intercalation
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Reduced graphene oxide (rGO) intercalated with a carbon black (CB) supported copper catalyst (Cu/rGO-CB) was employed in the synthesis of dimethyl carbonate (DMC) via liquid-phase oxidative carbonylation of methanol. The conversion of methanol and the space-time yield of DMC (STYDMC) over Cu/rGO-CB reached 5.6% and 2757 mg/(g h), higher than over a Cu/rGO catalyst, 4.7% and 2334 mg/(g h), respectively. The characterization indicates that CB particles, acting as spacers, ensured the high utilization of graphene layers and enhanced the interaction between Cu and the support, and the oxygen containing groups on the surface of CB play an important role in stabilizing Cu clusters. In comparison with Cu/rGO, the loss of copper concentration in Cu/rGO-CB is significantly decreased, from 15.37% to 1.96%. Catalyst reusability tests show that Cu/rGO-CB could be reused five times without almost any catalytic activity loss, implying distinct enhanced catalytic stability compared to the Cu/rGO catalyst.
- Shi, Ruina,Ren, Meijiao,Li, Haixia,Zhao, Jinxian,Liu, Shusen,Li, Zhong,Ren, Jun
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- Facile synthesis of potassium tetrathiooxalate – The “true” monomer for the preparation of electron-conductive poly(nickel-ethylenetetrathiolate)
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Herein, aiming at optimization of the polymerization process leading to a family of hole- and electron-conducting 1,1,2,2-ethenetetrathiolate-based polymers, such as poly(nickel-1,1,2,2-ethenetetrathiolate), poly[Kx(Ni-ett)], we investigated transformations of the monomer precursor 1,3,4,6-tetrathiapentalene-2,5-dione (TPD) occurring under polymerization conditions. We found that only one ring of TPD opens upon its reaction with potassium methoxide under inert conditions at room temperature which leads to the formation of potassium 2-oxo-1,3-dithiol-4,5-dithiolate (K2[3]). Heating of K2[3] under reflux in methanol solution under inert conditions opens the second ring, however the resulting product is not potassium ethenetetrathiolate (K4[2]), the product of an exhaustive methanolysis of TPD, but potassium tetrathiooxalate (K2[4]), the product of the decarbonylation of K2[3]. Preliminary experiments reveal that the involvement of K2[4] in the polymerization process is beneficial for reproducible formation of high quality 1,1,2,2-ethenetetrathiolate-based polymers suitable for thermoelectric applications.
- Tkachov, Roman,Stepien, Lukas,Roch, Aljoscha,Komber, Hartmut,Hennersdorf, Felix,Weigand, Jan J.,Bauer, Ingmar,Kiriy, Anton,Leyens, Christoph
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- Phosphinite-Ni(0) Mediated Formation of a Phosphide-Ni(II)-OCOOMe Species via Uncommon Metal-Ligand Cooperation
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Reversible transformations are observed between a phosphide-nickel(II) alkoxide and a phosphinite-nickel(0) species via a P-O bond formation coupled with a 2-e- redox change at the nickel center. In the forward reaction, the nickel(0) dinitrogen species (PPOMeP)Ni(N2) (2) and {(PPOMeP)Ni}2(μ-N2) (3) were formed from the reaction of (PPP)NiCl (1) with a methoxy anion. In the backward reaction, a (PPP)Ni(II) moiety was regenerated from the CO2 reaction of 3 with the concomitant formation of a methyl carbonate ligand in (PPP)Ni(OCOOMe) (7). Thus, unanticipated metal-ligand cooperation involving a phosphide based ligand is reported.
- Kim, Yeong-Eun,Oh, Seohee,Kim, Seji,Kim, Onnuri,Kim, Jin,Han, Sang Woo,Lee, Yunho
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- Synthesis of dimethyl carbonate from ethylene carbonate and methanol using TS-1 as solid base catalyst
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The titanium silicate molecular sieve, TS-1, exchanged with an aqueous solution of K2CO3 is an excellent heterogeneous catalyst for the synthesis of dimethyl carbonate by an ester exchange reaction between ethylene carbonate and methanol.
- Tatsumi,Watanabe,Koyano
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- Dimethyl carbonate synthesis from carbon dioxide using ceria-zirconia catalysts prepared using a templating method: Characterization, parametric optimization and chemical equilibrium modeling
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In this paper, a series of CexZr1-xO2 solid solution spheres were synthesized by exo- and endo-templating methods and tested for dimethyl carbonate (DMC) synthesis using direct conversion of CO2. The synthesized catalysts were characterized by X-ray diffraction (XRD), N2-physisorption, scanning electron microscopy (SEM), and CO2/NH3-temperature-programmed desorption (TPD). Formation of CexZr1-xO2 solid solutions with tetragonal and cubic crystal structures depending on cerium/zirconium compositions was confirmed by XRD analysis. The specific surface area of the mixed oxide decreased and the average pore diameter increased with an increase in the ceria content, with the exception of the mixed oxides with x = 0.4-0.5 i.e. Ce0.4Zr0.6O2 and Ce0.5Zr0.5O2. The basic and acidic site density of the synthesized catalysts was in the order: ZrO2 2 0.5Zr0.5O2, and the basic and acidic site density per unit area followed the same order. The best Ce0.5Zr0.5O2 catalyst was further used for the optimization of reaction conditions such as reaction time, reaction temperature, catalyst dose and reusability for DMC synthesis. Furthermore, study of chemical equilibrium modeling was done using the Peng-Robinson-Stryjek-Vera equation of state (PRSV-EoS) along with the van der Waals one-fluid reaction condition so as to calculate change of Gibbs free energy (ΔG°) and heat of reaction (ΔH°).
- Kumar, Praveen,With, Patrick,Srivastava, Vimal Chandra,Shukla, Kartikeya,Gl?ser, Roger,Mishra, Indra Mani
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p. 110235 - 110246
(2016)
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- PREPARATION OF DIMETHYL CARBONATE FROM METHANOL AND CARBON DIOXIDE IN THE PRESENCE OF Sn(IV) and Ti(IV) ALKOXIDES AND METAL ACETATES
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The synthesis of dimethyl carbonate by the reaction of methanol with carbon dioxide in the presence of metal alkoxides and metal carboxylates was studied.The best results have been achieved with Ti(IV) and Sn(IV) alkoxides which at 130 to 180 deg C and low CO2 pressures yield dimethyl carbonate in 30 to 100 mole percent or 40 to 130 mole percent yields with respect to the metal alkoxides, depending on the carbon dioxide (gaseous and solid one, respectively).The yields can be further increased up to 70-190 mole percent and 90-270 mole percent, respectively, by the use of chemical scavengers of the reaction water.
- Kizlink, Juraj,Pastucha, Ivan
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- Efficient, direct synthesis of dimethyl carbonate from CO2 using a solid, calcined zirconium phenylphosphonate phosphite catalyst
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Direct synthesis of dimethyl carbonate (DMC) from CO2 and methanol with 100 mol% selectivity using a solid, reusable, hydrophobic, calcined zirconium phenylphosphonate phosphite catalyst is reported for the first time. DMC yield as high as 26 mmol g-1 catalyst correlated with the concentration of acid and base sites is obtained.
- Unnikrishnan, Pulikkeel,Varhadi, Poonam,Srinivas, Darbha
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- Spectro-Electrochemical Examination of the Formation of Dimethyl Carbonate from CO and Methanol at Different Electrode Materials
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In this work, we report a fundamental mechanistic study of the electrochemical oxidative carbonylation of methanol with CO for the synthesis of dimethyl carbonate on metallic electrodes at low overpotentials. For the first time, the reaction was shown to take place on the metallic catalysts without need of oxidized metals or additives. Moreover, in-situ spectroelectrochemical techniques were applied to this electrosynthesis reaction in order to reveal the reaction intermediates and to shed light into the reaction mechanism. Fourier transformed infrared spectroscopy was used with different electrode materials (Au, Pd, Pt, and Ag) to assess the effect of the electrode material on the reaction and the dependence of products and intermediates on the applied potentials. It was observed that the dimethyl carbonate is only formed when the electrode is able to decompose/oxidize MeOH to form (adsorbed) methoxy groups that can further react with CO to dimethyl carbonate. Furthermore, the electrode needs to adsorb CO not too strongly; otherwise, further reaction will be inhibited because of surface poisoning by CO.
- Figueiredo, Marta C.,Trieu, Vinh,Eiden, Stefanie,Koper, Marc T.M.
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- Dehydrating agent effect on the synthesis of dimethyl carbonate (DMC) directly from methanol and carbon dioxide
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CO2emissions and global warming have increased with the growth of the world economy and industrialization. Direct synthesis of dimethyl carbonate (DMC) from CO2and methanol (CH3OH) has been considered a promising route from a green chemistry point of view due to global warming mitigation by CO2emission reduction. However, DMC yield, when obtained by direct synthesis, is limited due to unfavorable thermodynamics and catalyst deactivation by water formation in the reaction process. This problem motivated us to investigate the effect of dehydration on DMC production by direct synthesis. Herein, different dehydrating agents (2,2-dimethoxypropane, sodium sulfate, magnesium oxide and butylene oxide) were combined with molecular sieves to remove the water and minimize the reverse reaction. A new reactor presenting a compartment to accommodate molecular sieves in the gas phase was developed as well. The chemical/product analysis was carried out by gas chromatography and the results were used to calculate methanol conversion and DMC selectivity. The highest methanol conversion value was found for the combination of molecular sieves in the gas phase with 2,2-dimethoxypropane in the reaction liquid phase (methanol conversion = 48.6% and 88% selectivity). The results showed that dehydration systems may promote increased yield in direct DMC synthesis under mild conditions. The dehydration systems tested in this work exhibited excellent conversion and yield as compared to other reported studies.
- Bernard, Franciele Longaray,Carmona da Motta Resende, Maria Angélica,Einloft, Sandra,Faria, Douglas José,Moreira dos Santos, Leonardo,Selbacch Pinto, Ingrid
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- La-modified mesoporous Mg-Al mixed oxides: Effective and stable base catalysts for the synthesis of dimethyl carbonate from methyl carbamate and methanol
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A series of La-containing Mg-Al hydrotalcite-like (HTl) precursors with different La contents (Mg2+:Al3+:La3+ = 3:1:x, where x varies from 0 to 1.0) were synthesized using a co-precipitation method followed by hydrothermal treatment. X-ray diffraction and thermogravimetric measurements demonstrated that the yield of the HTl phase decreased with increasing La content. The La-modified Mg-Al mixed oxides (HTC-La) were then obtained by thermal decomposition of the corresponding HTl precursors, and the mesoporous structure was formed during calcination. It was demonstrated that the structure and surface basic properties of the HTC-La samples strongly depended on the amount of La additive. Simultaneously, the resulting HTC-La materials were used as solid base catalysts for the synthesis of dimethyl carbonate (DMC) from methyl carbamate (MC) and methanol. Then, the correlation between their basic properties and catalytic performance was studied in detail. The incorporation of a suitable amount of La into HTC-La catalysts was beneficial for the production of DMC, and a DMC yield of 54.3% with a high DMC selectivity of 80.9% could be achieved when x was tuned to 0.5 under the optimized reaction conditions. In addition, the HTC-La catalyst could be readily recycled while maintaining high catalytic activity and selectivity for DMC. Furthermore, in situ FTIR experiments were carried out to elucidate the adsorption behaviours of the reactants. On the basis of the experimental results, a plausible basic catalytic mechanism wherein MC and methanol were activated simultaneously on the basic sites of the catalyst was proposed for this catalytic reaction.
- Wang, Dengfeng,Zhang, Xuelan,Ma, Jie,Yu, Haiwen,Shen, Jingzhu,Wei, Wei
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- Kinetic study for the direct synthesis of dimethyl carbonate from methanol and CO2 over CeO2 at high pressure conditions
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The kinetics for the direct synthesis of dimethyl carbonate was studied over CeO2 at high pressure conditions in a batch reactor. Langmuir-Hinshelwood and Eley-Rideal mechanisms were proposed and compared by the performance of the respective reaction rate expression in fitting to the experimental kinetic data. The reactions were held at different temperatures (378-408 K), CO2/methanol molar ratios (1.1-4.0) and pressures (15-20 MPa) in order to adjust the kinetic parameters. An activation energy of 106 kJ mol-1, as well as the standard enthalpy and Gibbs energy of reaction (-20.10 and 31.50 kJ mol-1) were calculated from experiments. Furthermore, the changes in pressure revealed an effect on the kinetic constant, with an activation volume equal to -0.208 cm3 mol-1.
- Santos,Pereira,Silva,Loureiro,Rodrigues
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- The promotion and stabilization effects of surface nitrogen containing groups of CNT on cu-based nanoparticles in the oxidative carbonylation reaction
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N-doped carbon nanotubes (NCNTs)with different contents of N were prepared by pre-oxidation and subsequent N-doping strategy and employed as the supports to fabricate Cu-based catalysts for oxidative carbonylation of methanol. The supports and their corresponding catalysts were characterized thoroughly by BET, XPS, XRD, H2-TPR, TEM, N2O chemisorption, CO-TPD, CH3OH-TPD and ICP-OES measurements. It is found that the increase of oxygen containing groups generated by pre-oxidation can effectively improve the content of the nitrogen containing groups during the subsequent N-doping process. The nitrogen containing groups, especially the pyridine N groups, serving as the preferred anchoring site, significantly promotes the dispersion of Cu species. With the increased content of N from 0 to 5.2%, the dispersion of Cu species increases from 11.0 to 21.6% and the space time yield of DMC increases from 150.5 to 1789.6 mg g?1h?1. Moreover, the incorporation of nitrogen containing groups enhances the interaction between Cu species and CNT support, which suppresses the auto-reduction of Cu2+ to Cu+ and Cu0, while improves the anti-agglomeration, anti-oxidation and anti-leaching properties of Cu species. From the perspective of stability, the space time yield of DMC for Cu/CNT decreases from 150.5 to 86.9 mg g?1 h?1 after four consecutive runs, while that of Cu/NCNT200 slightly decreases from 1789.6 to 1557.9 mg g?1 h?1, and the declined degrees are 42.3% and 12.9%, respectively. The superior dispersion, anti-agglomeration, anti-oxidation and anti-leaching properties of Cu species as well as the promotion effect of pyridine N groups are contributed to the increased activity and stability of the Cu/NCNT200 catalyst.
- Zhang, Guoqiang,Zhao, Dan,Yan, Junfen,Jia, Dongsen,Zheng, Huayan,Mi, Jie,Li, Zhong
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- Synthesis of mesoporous carbon nitride: Via a novel detemplation method and its superior performance in base-catalyzed reactions
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A series of mesoporous graphitic carbon nitride materials have been synthesized using dicyandiamide as a precursor by a nanocasting method through a new detemplation process. Alkaline solutions could effectively eliminate hard siliceous templates, and ordered mesostructures have been well retained over the final synthesized CND materials. Fourier transform infrared and X-ray photoelectron spectroscopy characterization revealed that the employment of alkaline solution during the synthesis of the CND samples facilitated the condensation of tri-s-triazine fragments and thus enhanced the amount of bridging N species. According to the profiles of CO2 temperature programmed desorption and elemental analysis, the detemplating agent could not only preserve the original basic sites but also improve the overall basic intensity of the mesoporous CND samples. In base-catalyzed reactions, represented by Knoevenagel condensation and transesterification reactions, the mesoporous CND materials demonstrated excellent and stable catalytic performance, which is especially much higher than that of the mesoporous sample detemplated by traditional HF solution.
- Xu, Jie,Wang, Yue,Shang, Jie-Kun,Jiang, Quan,Li, Yong-Xin
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- Template-derived carbon: An unexpected promoter for the creation of strong basicity on mesoporous silica
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Template-derived carbon is demonstrated to effectively promote the creation of strong basicity on mesoporous silica, for the first time. New materials owning ordered mesoporous structure, strong basicity, and excellent catalytic activity are thus successfully constructed at low temperatures, which are impossible to achieve using conventional methods.
- Sun, Lin-Bing,Liu, Xiao-Yan,Li, Ai-Guo,Liu, Xiao-Dan,Liu, Xiao-Qin
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- Driving dimethyl carbonate synthesis from CO2 and methanol and production of acetylene simultaneously using CaC2
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The synthesis of dimethyl carbonate (DMC) from CO2 and methanol is a very interesting reaction, but is thermodynamically limited. In this work, CaC2 was used to consume the water produced in the reaction to shift the reaction equilibrium, and C2H2 was produced at the same time. This is the first work on the combination of driving a thermodynamically unfavorable reaction and producing C2H2 using CaC2.
- Zhang, Zhaofu,Liu, Shuaishuai,Zhang, Lujun,Yin, Shuai,Yang, Guanying,Han, Buxing
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- Kinetics of dimethyl carbonate synthesis from methanol and carbon dioxide over ZrO2-MgO catalyst in the presence of butylene oxide as additive
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A kinetic investigation of dimethyl carbonate (DMC) synthesis from methanol and CO2 over ZrO2-MgO was performed by using butylene oxide as a chemical trap for the water formed during the reaction. The effect of the catalyst amount, the stirring speed, the temperature, as well as the amount of butylene oxide on the reaction rate and the selectivity to DMC was studied. The analysis of the reaction pathway suggests that DMC and butylene glycol are formed via the reaction of adsorbed mono-methoxycarbonate intermediate and methoxybutanol or methanol. A kinetic model was developed based on the reaction mechanism and it was in agreement with the experimental data. The apparent activation energy for the formation of DMC was 62 kJ/mol.
- Eta, Valerie,M?ki-Arvela, P?ivi,W?rn, Johan,Salmi, Tapio,Mikkola, Jyri-Pekka,Murzin, Dmitry Yu.
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- ZrO2 Nanocrystals As Catalyst for Synthesis of Dimethylcarbonate from Methanol and Carbon Dioxide: Catalytic Activity and Elucidation of Active Sites
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The catalytic activity of zirconium oxide (ZrO2) nanocrystals for the reaction of carbon dioxide (CO2) with methanol to form dimethylcarbonate (DMC) was investigated. ZrO2 nanocrystals prepared by hydrothermal synthesis at various temperatures were compared. The size of the ZrO2 nanocrystals monotonically increased with the hydrothermal temperature, according to specific surface area, transmission electron microscope measurements, and their X-ray diffraction peak widths. The ZrO2 nanocrystals prepared by hydrothermal synthesis were found to exhibit high catalytic activity owing to their high surface area and catalytically active surfaces arising from their high crystallinity. Next, adsorbed species generated from CO2 on the ZrO2 surfaces were measured using CO2 temperature-programmed desorption (TPD) and in situ FT-IR spectroscopy. The results confirmed the presence of several kinds of adsorbed species including bidentate bicarbonate (b-HCO3-), bidentate carbonate (b-CO32-), and monodentate carbonate (m-CO32-). The relationship between the amounts of these surface species and the catalytic activity of the ZrO2 was investigated for the first time. The amount of the bidentate species (b-HCO3- and b-CO32-) was found to correlate well with the catalytic activity, demonstrating that the surface sites that afford these species contribute to the catalytic activity for this reaction.
- Akune, Takayuki,Morita, Yusuke,Shirakawa, Shinya,Katagiri, Kiyofumi,Inumaru, Kei
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- Selective carbonylation of methanol to dimethyl carbonate by gas-liquid-solid-phase boundary electrolysis
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Selective and efficient electrochemical carbonylation of MeOH to DMC was performed over PdCl2/VGCF (vapor grown carbon fiber) anode by utilizing the three-phase boundary electrolysis at 1 atm (CO) and 298 K.
- Yamanaka, Ichiro,Funakawa, Akiyasu,Otsuka, Kiyoshi
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- Dimethyl carbonate synthesis via transesterification of ethylene carbonate and methanol using ionic liquid catalysts immobilized on mesoporous cellular foams
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Dimethyl carbonate (DMC) was synthesized via transesterification of ethylene carbonate and methanol with ionic liquid catalysts. For this reaction, 1,4-diazobicyclo[2.2.2]octane (DABCO), [Choline]OH, and [BMIM]Cl were used as a homogeneous catalyst, and hydrotalcite, [DABCO]OH@MCF, [DABCO]Cl@MCF, and DABCO/MCF were used as a heterogeneous catalyst. To support the ionic liquids, mesoporous cellular foam (MCF) was prepared and characterized by SEM, TEM and BET surface area analyzer. The average cell and window sizes of the prepared MCF were 34.4 and 21.3 nm, respectively. The prepared MCF had a well structured three-dimensional structure. Among the homogeneous catalysts used, DABCO showed the highest DMC yield about 84 %, and among the heterogeneous catalysts, [DABCO]OH@MCF showed the highest DMC yield about 77 %. In the reusability test of the used catalysts, there was only 8 % point decrease in DMC yield with [DABCO]OH@MCF, whereas 58 percent point decrease in DMC yield with DABCO/MCF after four times recycling tests. The effects of an anion on the catalytic activity were investigated. The optimum reaction condition for DMC synthesis was also investigated with [DABCO]OH@MCF catalyst.
- Lee, Kwang-Hyeok,Lee, Seungjea,Shin, Dongil,Hahm, Hyun-Sik
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- Synthesis of Dimethyl Carbonate by Electrolytic Carbonylation of Methanol in the Gas Phase
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Electrolytic carbonylation of methanol has been attempted in the gas phase under atmospheric pressure at 343 K. The graphites added with PdCl2 and CuCl2 are favorable anodes for the synthesis of dimethyl carbonate (DMC). The formation of DMC occurs at a lower applied voltage than that for dimethoxy methane and methyl formate. However, a considerable CO2 formation accompanies the DMC formation.
- Otsuka, Kiyoshi,Yagi, Toshikazu,Yamanaka, Ichiro
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- Copper supported on N-heterocyclic carbene-functionalized porous organic polymer for efficient oxidative carbonylation of methanol
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A new heterogeneous catalyst for the oxidative carbonylation of methanol to dimethyl carbonate based on copper coordinated in N-heterocyclic carbene-functionalized porous organic polymer (Cu@PQP-NHC) was presented. The solid catalyst that featured relatively large surface area, hierarchical pore structure, and excellent swelling property, was prepared via a facile copolymerization reaction of tetra-vinylphosphonium salt and bis-vinylimidazolium salt, followed by successful immobilization of CuCl. Accordingly, the resulting Cu@PQP-NHC showed excellent catalytic performance for the oxidative carbonylation of methanol. A 10 mmol/l of Cu usage was sufficient for 9.3percent conversion of methanol with a high TOF number of 57 h?1. Importantly, the catalyst was easily recovered by simple centrifugation, and could be reused up to 10 consecutive recycles without obvious loss of its initial activity. Also, the solid catalyst showed negligible Cu leaching during the recycling, and 99percent Cu species was still retained after reusing 10 times. The results in this study highlights the advantages of porous organic polymer supported NHC-Cu catalyst as a highly active and stable heterogeneous catalyst, providing a promising route for the synthesis of dimethyl carbonate.
- Lei, Yizhu,Fan, Meitao,Lan, Guosong,Li, Guangxing
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- NiO/CeO2-ZnO nano-catalysts for direct synthesis of dimethyl carbonate from methanol and carbon dioxide
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XNiO/CeO2(0.7)-ZnO(0.3) (X =0, 1, 5, 10, and 15) nano-catalysts were prepared by a wet impregnation method with a variation of NiO content (X, wt%). The prepared catalysts were then applied to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Successful formation of XNiO/CeO2(0.7)-ZnO(0.3) nano-catalysts was confirmed by XRD and ICP-AES analyses. Acidity and basicity of XNiO/CeO2-ZnO were measured by NH3-TPD (temperature-programmed desorption) and CO2-TPD experiments, respectively, with an aim of elucidating the effect of acidity and basicity of the catalysts on the catalytic performance in the reaction. It was revealed that the catalytic activity of XNiO/CeO2(0.7)-ZnO(0.3) was closely related to both acidity and basicity of the catalysts. The amount of dimethyl carbonate produced over XNiO/CeO2(0.7)-ZnO(0.3) increased with increasing acidity and basicity of the catalysts. Thus, both acidity and basicity of the catalysts played important roles in determining the catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide.
- Kang, Ki Hyuk,Lee, Chang Hoon,Kim, Dong Baek,Jang, Boknam,Song, In Kyu
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- Phosphoric acid intercalated Mg-Al hydrotalcite-like compounds for catalytic carboxylation reaction of methanol in a continuous system
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Mg-Al-hydrotalcite-like catalysts (HTlcs) with different amount of P/Mg molar ratio were prepared via co-precipitation method and calcined at 450 °C. The synthesized catalysts were tested in the direct-carboxylation reaction of methanol in gas phase in a continuous system such as chemical route for CO2 valorization. Activities around 2% with total selectivity towards the dimethyl carbonate (DMC) was obtained at moderate temperatures (150 °C) with both Mg/Al mixed oxides (HTO) and phosphated Mg/Al mixed oxides (HTc-9c). Even though the conversion increased until 16% at higher temperatures (200 °C), the selectivity with both catalysts (HTO and HTc-9c) decreased due to the decomposition of DMC to dimethyl ether (DME). Nevertheless, the catalyst with P showed less DMC decomposition and a higher selectivity towards the desired product. This is explained by the presence of orthophosphate species bonded to the Al3+ metals of the HTs (O-P(OAl)3) which give to the catalyst a higher structural stability and specific acid properties. In addition, the solids were characterized in-depth by XRD, ICP, NH3-TPD, FTIR, Raman, 27Al and 31P MAS NMR spectroscopy and SEM.
- Bougacha Ghorbel, Salwa,Medina, Francisco,Ghorbel, Abdelhamid,Segarra, Anna M.
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- CuCl catalyst heterogenized on diamide immobilized SBA-15 for efficient oxidative carbonylation of methanol to dimethylcarbonate
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CuCl has been successfully immobilized on a novel diamide modified SBA-15, and proven to be an efficient heterogenized catalyst for the oxidative carbonylation of methanol to dimethylcarbonate.
- Cao, Yong,Hu, Jun-Cheng,Yang, Ping,Dai, Wei-Lin,Fan
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- Utilization of environmentally benign dicyandiamide as a precursor for the synthesis of ordered mesoporous carbon nitride and its application in base-catalyzed reactions
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Assisted by a new dissolution procedure, dicyandiamide (DCDA), an environmentally benign and cheap precursor, has been employed for the synthesis of mesoporous carbon nitride (CN) materials through a nanocasting approach. The synthesized mesoporous materials possessed high specific surface areas (269-715 m2g-1) with narrow pore-size distributions (about 5 nm) and faithfully replicated the mesostructures of the SBA-15 and FDU-12 templates. Several characterization techniques, including XRD, SAXS, TEM, Raman and FTIR spectroscopy, XPS, and CO2-TPD, were used to analyze the physicochemical properties of these materials and the results showed that the mesoporous CND materials had graphitic-like structures and consisted of CN heterocycles, as well as amino groups. In a series of Knoevenagel condensation reactions, as exemplified by the reaction of various aldehydes and nitriles, these mesoporous CND materials demonstrated high and stable catalytic activities, owing to an abundance of basic sites.
- Xu, Jie,Chen, Ting,Jiang, Quan,Li, Yong-Xin
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- The Influence of Iron Group Promoters on the Synthesis of Dimethyl Carbonate over CuY Catalysts Prepared via Modified Vapor Impregnation Method
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Abstract: CuY and CuMY (M = Fe, Co, Ni) catalysts were prepared by modified vapor impregnation using cupric acetylacetonate as copper source and M acetylacetonate as promoter. The catalysts were evaluated in heterogeneous catalytic vapor phase oxidative carbonylation of methanol to dimethyl carbonate (DMC). The catalyst samples were analyzed by XRD, H2-TPR, XPS, CO-TPD, and NH3?TPD, and their catalytic performance was assessed in a fixed-bed reactor. The experimental results indicate that all introduced species were well dispersed on zeolite Y, and the addition of iron group promoters have effect on the Cu+ contents, acidity and CO adsorption-desorption performance. Finally the influence of various promoters was examined with the aim of increasing space-time yield of DMC from methanol. Space-time yield of DMC was increased with the addition of iron group promoters in the order Fe? Co Ni, but the selectivity follows the order of Fe Ni Co, respectively.
- Yuchun Wang,Liu, Zhaorong,Tan, Chao,Sun, Hong,Li, Zhong
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p. 705 - 712
(2021/04/22)
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- Method for synthesizing dimethyl carbonate through transesterification
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The invention relates to a method for synthesizing dimethyl carbonate through transesterification, and belongs to the technical field of chemical engineering. According to the method, propylene carbonate or ethylene carbonate and methanol are used as raw materials, guanidine salt ionic liquid is used as a catalyst, dimethyl carbonate is synthesized through transesterification, the use amount of the ionic liquid is 0.1%-5% of the total mass of methanol and propylene (or ethylene) carbonate, the reaction pressure is 50-200 kPa, the reaction temperature is 60-95 DEG C, and the reaction time is 0.5-4 h. The ionic liquid catalyst provided by the invention has good catalytic activity and can be recycled, and the method for producing dimethyl carbonate has the advantages of simple process flow, mild reaction conditions, environmental friendliness, low production cost and the like, and is a novel method for easily realizing industrial production.
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Paragraph 0021-0028; 0031; 0032; 0033
(2021/07/31)
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- Urea-Functionalized Swelling Poly(ionic liquid)s as Efficient Catalysts for the Transesterification and Hydrolysis of Ethylene Carbonate
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Urea-functionalized poly(ionic liquid)s (PILs) were synthesized through polymerization of urea tethered imidazolium ionic liquid monomers (urea-IL) with sodium acrylate, and N,N′-methylenebisacrylamide (MBA) as a crosslinker. Close-packed and interconnected pores (1–4 (Formula presented.)) under swollen state could be observed from the cryogenic scanning electron microscopy (cryo-SEM) images. The promising catalytic activity of the PILs was illustrated for the transesterification reaction of ethylene carbonate with methanol. High activity and selectivity could be achieved by using poly(urea-IL)-n catalysts, which was similar to that of corresponding homogeneous ionic liquid catalysts. The urea tethered imidazolium in PILs acted as hydrogen-bonding donor to activate ethylene carbonate and intermediate 2-hydroxyethyl methyl carbonate (HEMC) for enhancing catalytic activity. The swelling ability of urea-functionalized PILs in methanol enabled active urea sites accessible for substrates. However, the complete conversion of ethylene carbonate was limited by reversible reaction between ethylene carbonate and HEMC. A possible synergistic activation mechanism for the transesterification reaction was proposed and supported by NMR titrations. The catalyst can be reused and recycled five times with stable activity. Furthermore, urea-functionalized swelling PILs also exhibited high catalytic activity for the hydrolysis of ethylene carbonate.
- Hu, Hao,Wang, Xin,Chen, Bihua,Gao, Guohua
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p. 3945 - 3952
(2021/07/31)
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- One-step bulk fabrication of a CaO/carbon heterogeneous catalyst from calcium citrate for rapid synthesis of dimethyl carbonate (DMC) by transesterification of ethylene carbonate (EC)
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Dimethyl carbonate (DMC) is well known as an extremely industrially valuable substance. The demand for high-efficiency synthesis of DMC has greatly driven the exploration of novel catalysts and their low-cost preparation methods. Herein, a novel method for the rapid batch preparation of CaO/carbon catalysts using calcium citrate (CaCi) was provided, and these catalysts were used to catalyze the transesterification reaction of methanol and ethylene carbonate (EC) to synthesize DMC and ethylene glycol (EG). Accordingly, the structure and properties of the catalysts were characterized using XRD, FTIR, N2adsorption-desorption, TG, TG-IR, CO2-TPD, XPS, SEM, TEM and ICP-OES techniques. Meanwhile, the effect of various process conditions such as carbonization temperature, reaction temperature, reaction time and catalyst amount has been extensively evaluated. Under the optimal process parameters, the conversion of EC and the selectivity of DMC and EG were 81.2, 99.3 and 99.5%, while the turnover number (TON) and turnover frequency (TOF) were 54.1 and 162 h?1, respectively. Furthermore, kinetic analysis was carried out, and the value ofk(reaction rate constant) was ≈0.159 mol L?1min?1. The reusability was also investigated.
- Wei, Qiang,Zhang, Gang,Yao, Jie,Chen, Xuejun,Wang, Gongying,Yang, Xiangui
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supporting information
p. 5540 - 5550
(2021/04/06)
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- Preparation method of dialkyl carbonate
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The invention relates to a preparation method of dialkyl carbonate. The method comprises the following steps: by using cyclic carbonate and monohydric alcohol as raw materials, carrying out transesterification under the catalysis of triazole onium ionic liquid to obtain the dialkyl carbonate. According to the brand-new method for preparing the dialkyl carbonate, the cyclic carbonate and the monohydric alcohol are catalyzed by using the triazolium ionic liquid to be subjected to transesterification to obtain the dialkyl carbonate, and the dialkyl carbonate prepared by using the method has relatively high selectivity and conversion rate; and the selectivity of the obtained dialkyl carbonate can reach 99.5%. Compared with a method for preparing dialkyl carbonate in the prior art, the triazolium ionic liquid catalyst used in the invention has the advantages of high catalytic efficiency, high stability, no need of other solvents or cocatalysts, mild reaction conditions and the like, and has high industrial application value.
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Paragraph 0051-0079
(2021/05/01)
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- Boosting the methanolysis of polycarbonate by the synergy between ultrasound irradiation and task specific ionic liquids
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In an attempt to perform polycarbonate chemical recycling in a more sustainable way, we took into consideration the combined use of ultrasound irradiation and task specific ionic liquids. Towards this aim, the methanolysis of polycarbonate, into dimethylcarbonate and bisphenol A, was carried out in the presence of cholinium-based ionic liquids featuring anions derived from amino acids and other eco-friendly species. The target process was optimized in terms of both energy and material amounts as well as in terms of the nature of the catalysts used. The proposed protocol allowed high conversion and yields of bisphenol A to be obtained, under milder conditions compared to the ones so far reported in the literature, perfectly fulfilling green chemistry principles. The best performing catalyst can be reused without significant loss in performance and the methodology can be successfully applied to post-consumer polycarbonate samples. This journal is
- D'Anna, Francesca,Sbacchi, Maria,Infurna, Giulia,Dintcheva, Nadka Tz.,Marullo, Salvatore
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supporting information
p. 9957 - 9967
(2021/12/24)
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- Method for direct conversion of carbon dioxide to dialkyl carbonates using ethylene oxide as feedstock
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A method for co-production of high purity dimethyl carbonate and mono-ethylene glycol by applying a reactor, such as a membrane reactor and/or an adsorbent-catalytic reactor by capturing and reacting carbon dioxide with methanol and ethylene oxide. Carbon dioxide may be recovered from primary sources (utilities and industrial processes) by a membrane or solid adsorbent, and subsequently converted to an intermediate hydroxy-ethyl-methyl carbonate by reacting with ethylene oxide and methanol. For high-purity carbon dioxide (obtained by carbon capture technologies or from an ethanol fermentation process), the membrane reactor is replaced with a catalytic reactor for direct conversion of carbon dioxide to hydroxy-ethyl-methyl carbonate by reacting with ethylene oxide and methanol. The hydro-ethyl-methyl carbonate is further reacted with methanol for conversion to dimethyl carbonate. A combination of heterogeneous and homogeneous catalysts is implemented for an effective conversion of carbon dioxide. An integrated reactive distillation process using side reactors is used for facilitating catalytic reaction for production of high purity dimethyl carbonate.
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Page/Page column 17-20
(2021/03/11)
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- METHOD FOR PRODUCING CARBON DIOXIDE DERIVATIVE
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PROBLEM TO BE SOLVED: To provide a method for producing a useful carbon dioxide derivative from carbon dioxide with low energy. SOLUTION: An amine is caused to absorb carbon dioxide, and without separating the carbon dioxide, it is then reacted with an acid catalyst and an olefin, thereby producing a carbon dioxide derivative, which serves as a raw material for polyurethane. SELECTED DRAWING: None COPYRIGHT: (C)2021,JPOandINPIT
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Paragraph 0033; 0036
(2021/06/25)
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- SYSTEM AND PROCESS FOR CO-PRODUCING DIMETHYL CARBONATE AND ETHYLENE GLYCOL
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A system and a process for co-producing dimethyl carbonate and ethylene glycol. The system comprises an interconnected ethylene carbonate preparation unit and an ethylene carbonate alcoholysis unit. The ethylene carbonate preparation unit comprises a fixed bed reactor and a light-component stripping column connected to each other. The fixed bed reactor is filled with a supported ionic liquid catalyst. The process comprises the steps of: reacting carbon dioxide and ethylene oxide as raw materials in the fixed bed reactor to produce ethylene carbonate, purifying the ethylene carbonate and then mixing it with an alcoholysis reaction catalyst, and reacting the mixture with methanol in a reactive distillation tower, producing dimethyl carbonate and ethylene glycol. The process increases the conversion rate of ethylene oxide and avoids the need for a process of separating conventional homogeneous catalysts from ethylene carbonate, thereby reducing process energy consumption and simplifying process procedures.
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Page/Page column 4-6
(2021/10/30)
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- Method for producing organic carbonate
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To provide a method for producing organic carbonate from carbon dioxide as a raw material without producing water as a by-product.SOLUTION: Provided is a method for producing an organic carbonate, which comprises reacting alkoxysilane with carbon dioxide.SELECTED DRAWING: None
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Paragraph 0034; 0074; 0078
(2021/12/07)
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- Lewis acid sites in MOFs supports promoting the catalytic activity and selectivity for CO esterification to dimethyl carbonate
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CO esterification to dimethyl carbonate (DMC) is an attractive route, although the catalyst is the main problem restricting the industrialization of this route. Supported palladium catalysts have been often used for this route. However, the effect of the support is not always clear. In this work, we firstly introduced three metal-organic frameworks (MOFs) materials as catalyst supports, namely UiO-66, MIL-101 and MOF-5, and studied the effect of Lewis acid sites in the MOFs supports on the catalytic activity and selectivity for CO esterification to DMC. Interestingly, the Pd(ii)/UiO-66 catalyst exhibits superior catalytic performance to the other catalysts, with 87.9% CO conversion and 98.5% DMC selectivity due to the abundant Lewis acid sites in UiO-66. It was proven that UiO-66 with more defects would have a large number of Lewis acid sites, and the catalytic performance was positively correlated with the number of Lewis acid sites in MOFs supports, which can be demonstrated by characterization by NH3-TPD, pyridine-IR, XPS and in situ DRIRS. The current work not only revealed the relationship between the Lewis acidity of the support and catalytic performance, but also promotes the development of practical catalysts for CO esterification to DMC.
- Guo, Guo-Cong,Jing, Kai-Qiang,Tan, Hong-Zi,Wang, Zhi-Qiao,Xu, Yu-Ping,Xu, Zhong-Ning
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p. 1699 - 1707
(2020/04/09)
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- Method for directly preparing dimethyl carbonate through reaction of low-temperature high-efficiency catalytic urea and methanol (by machine translation)
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The invention relates to a method for directly preparing dimethyl carbonate through reaction of urea and methanol at low temperature, and a method for directly preparing dimethyl carbonate by using the high-efficiency solid-phase Mg - Ga catalyst. 2 O3 /CeO2 - Al2 O3 The, method has the advantages that the yield of, dimethyl carbonate can be further improved, the, reaction activity and, selectivity are high, 100%, the conversion rate of the by-product is lower than that of dimethyl carbonate, and the selectivity of dimethyl carbonate to dimethyl carbonate is greater than or equal to and equal to or greater than or equal to and equal. 99.2% to or greater than about. (by machine translation)
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Paragraph 0029; 0032-0035; 0038-0041; 0044-0046; 0054
(2020/02/05)
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- Synthesis of nitrogen-containing ordered mesoporous carbon materials with tunable nitrogen distributions and their application for metal-free catalytic synthesis of dimethyl carbonates
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Dicyandiamide (DCDA) was utilized as a facile nitrogen source for the fabrication of nitrogen-containing ordered mesoporous carbon (NOMC) samples via a one-pot soft-templating approach under aqueous phase. X-ray diffraction, N2 adsorption–desorption, Transmission electron microscopy, Scanning electron microscopy, Raman and X-ray photoelectron spectroscopy have been applied to analyze the physicochemical properties of the synthesized NOMC materials. The characterization results showed that the textural parameters (545–589 m2 g?1), graphitic crystallinity and distribution of various nitrogen species of the synthesized NOMC materials were largely dependent on the adding mass of DCDA. Besides DCDA, NOMC materials have been also successfully fabricated by employing urea and melamine as nitrogen sources. As metal-free heterogeneous catalysts, the NOMC materials showed good catalytic activity and selectivity in the transesterification of ethylene carbonate to dimethyl carbonate, affording a maximum yield of dimethyl carbonate up to 76 % at 3 h under 120 °C.
- Gan, Yu-Lin,Wen, Lin-Zhi,Xu, Jie,Xue, Bing
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- SYNTHETIC METHOD AND SYNTHETIC SYSTEM
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Provided is a synthesis method comprising a first step of producing a carbonate compound from carbon monoxide and an alcohol-based compound at an anode of a first electrochemical cell comprising a cathode and the anode, and a second step of synthesizing a first product by a dealcoholization reaction of the carbonate compound, wherein an alcohol-based compound eliminated in the second step is recycled in the first step.
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Paragraph 0252; 0255; 0271-0272
(2020/04/10)
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- Preparation Method of Dialkylcarbonate using selenite catalyst and Composition Comprising Dialkylcarbonate Prepared Therefrom
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The present invention relates to a composition which contains: an alkali metal selenite catalyst of chemical formula 2, an alkali metal alkyl selenite catalyst of chemical formula 3, or dialkyl carbonate (DAC) of chemical formula 1, obtained by an oxidation carbonylation process which conducts a reaction of alcohol of chemical formula 4: ROH with a mixed gas of carbon monoxide (CO) and oxygen (O_2); and a selenium-containing by-product, wherein the content of the selenium-containing by-product is 7,000 ppm or less. In addition, the present invention provides a method for manufacturing DAC of the chemical formula 1. The composition according to the present invention can produce DAC of the chemical formula 1 in an economically feasible yield compared to a conventional carbonylation process.COPYRIGHT KIPO 2020
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Paragraph 0095-0110
(2020/05/13)
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- Method for preparing dimethyl carbonate through basic ionic liquid catalysis one-step method
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The invention discloses a method for preparing dimethyl carbonate through a basic ionic liquid catalysis one-step method, and belongs to the technical field of chemical synthesis. According to the method for preparing the dimethyl carbonate, the basic ionic liquid is used as a catalyst, and the dimethyl carbonate is synthesized by a one-step method through catalyzing a cycloaddition reaction of carbon dioxide and alkylene oxide and an ester exchange reaction of cyclic carbonate and methanol. The basic ionic liquid is composed of dication X and two anions Y and Z, wherein the dicationX is formed by connecting two cations X through a carbon chain composed of 2-6 methylene groups. The basic ionic liquid is high in catalytic efficiency, the conversion rate of epoxypropane orethylene oxide can reach 99% or above, and the yield of dimethyl carbonate can reach 60% or above.
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Paragraph 0028-0067
(2020/07/27)
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- Method for thermally catalyzing methanol and carbon dioxide to generate dimethyl carbonate by using copper/cuprous oxide nanosheet catalyst
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The invention provides a method for thermally catalyzing methanol and carbon dioxide to generate dimethyl carbonate by using a copper/cuprous oxide nanosheet catalyst, and belongs to the technical field of organic synthesis. According to the method, organic matters are used as solvents and copper/cuprous oxide nanosheets are used as catalysts at lower temperature and lower pressure, and the dimethyl carbonate is generated by directly utilizing the one-pot reaction of carbon dioxide and methanol. The method is high in atom utilization rate, environment-friendly, simple in reaction step, low incost and suitable for large-scale production.
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Paragraph 0059-0072
(2020/08/27)
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- Protic ionic liquid-promoted synthesis of dimethyl carbonate from ethylene carbonate and methanol
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In this work, the protic ionic liquid [DBUH][Im] (1,8-diazabicyclo[5.4.0]-7-undeceniumimidazolide) was developed as an efficient catalyst for the transesterification of ethylene carbonate with methanol to produce dimethyl carbonate. At 70 °C, up to 97% conversion of ethylene carbonate and 91% yield of dimethyl carbonate were obtained with 1 mol% [DBUH][Im] (relative to ethylene carbonate) as catalyst in 2 h. Even at room temperature, the conversion of ethylene carbonate can reach 94% and the yield of dimethyl carbonate can approach 81% for 6 h. Catalytic mechanism investigation showed the high catalytic efficiency of this ionic liquid results from the synergistic activation effect, wherein the cation can activate ethylene carbonate and the anion can activate methanol through hydrogen bond formation. Although the reusability of the ionic liquid need to be further improved, high efficiency and commercial availability of [DBUH][Im] render it a promising catalyst for the preparation of dimethyl carbonate.
- Song, Yu,He, Xing,Yu, Bing,Li, Hong-Ru,He, Liang-Nian
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p. 667 - 672
(2019/08/16)
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- Metal-free synthesis of dimethyl carbonate: Via transesterification of ethylene carbonate catalyzed by graphitic carbon nitride materials
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Catalytic transesterification reaction between a cyclic carbonate and a low alcohol is the most important and practical strategy for the manufacture of dimethyl carbonate and other alkyl carbonates. However, most developed heterogeneous catalysts have potential metal and halide contamination. Herein, a graphitic carbon nitride (g-C3N4) material has been synthesized, thermally exfoliated, and treated with an alkaline solution. The physicochemical properties of eg-C3N4 materials have been analyzed by XRD, TG, N2 adsorption-desorption, FT-IR, UV-vis, and XPS spectroscopy. The characterization results reveal that the exfoliation has effectively enhanced the surface area of g-C3N4, and alkaline treatment could lead to the deprotonation of eg-C3N4, depending on the treatment temperature and alkaline solution. In the transesterification reaction between ethylene carbonate and CH3OH, the eg-C3N4-NH3 catalyst demonstrates superior catalytic activity to the pure g-C3N4, eg-C3N4 and eg-C3N4-HCl, affording a maximum DMC yield of 60% at 393 K. Furthermore, the eg-C3N4-NH3 shows good catalytic reproducibility and versatility for other substrates.
- Gan, Yu-Lin,Hu, Xiao-Qian,Wen, Lin-Zhi,Xu, Jie,Xue, Bing
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supporting information
p. 3215 - 3223
(2020/03/06)
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- Preparation method of dimethyl carbonate
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The invention discloses a dimethyl carbonate preparation method, which comprises: contacting a raw material containing ethylene carbonate and methanol with a catalyst, and carrying out reaction to obtain dimethyl carbonate, wherein the catalyst comprises an ionic liquid; the ionic liquid comprises anions and cations; the cation has a structure as shown in a formula I or a formula II. According tothe preparation method of dimethyl carbonate, a series of developed strongly basic ionic liquids are used for ester exchange reaction of ethylene carbonate and methanol to synthesize dimethyl carbonate and ethylene glycol, extremely high reaction activity is achieved, reaction equilibrium can be achieved after reaction for 5 min at 68-70 DEG C even if the content of the catalyst is 0.3wt%, and certain catalytic activity is achieved even at 0 DEG C.
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Paragraph 0127; 0129-0132; 0136-0148; 0151-0177
(2020/05/02)
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- High catalytic activity of CuY catalysts prepared by high temperature anhydrous interaction for the oxidative carbonylation of methanol
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CuY catalysts were prepared by high temperature anhydrous interaction between NH4Y zeolite and copper(ii) acetylacetonate Cu(acac)2 and the activities were measured for the oxidative carbonylation of methanol to dimethyl carbonate under atmospheric pressure. The bulk and surface properties of the as-prepared catalyst were characterized by XRD, H2-TPR and XPS techniques. The activation atmosphere of the CuY catalyst and the testing temperature of the catalytic activity was systematically studied. During activation, nitrogen promotes the auto-reduction of Cu2+ to form the Cu+ active center, but deposited carbon on the surface of the CuY catalyst covers the active center, even plugging the channel, resulting in lower catalytic activity. Oxygen eliminates deposited carbon, but is not so good for the auto-reduction of Cu2+. Nitrogen doped with a small amount of oxygen not only eliminates the deposited carbon, but also promotes the auto-reduction of Cu2+ to form more Cu+ active centers. With the testing temperature increasing, the catalytic activity increases first and then decreases. When the testing temperature is 170 °C, the CuY catalyst with satisfactory activity and stability showed an excellent catalytic activity with 525.1 mg g-1 h-1 space time yield of DMC (STYDMC) and 18.9% methanol conversion. Then the longevity was investigated at 170 °C for 150 h. During the initial reaction period of 40 h, the STYDMC value was constant. In the next 20 h, the catalytic activity slightly decreased. But in the last 90 h, the catalytic performance is very stable and the STYDMC value remains 480 mg g-1 h-1. The main cause of deactivation is the growth of the particles.
- Wang, Yuchun,Liu, Zhaorong,Tan, Chao,Sun, Hong,Li, Zhong
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p. 3293 - 3300
(2020/02/04)
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- DISUBSTITUTED OXALATE AND DISUBSTITUTED CARBONATE PRODUCTION FROM AN OXALATE SALT AND ALCOHOL
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Processes for producing a disubstituted oxalate and/or disubstituted carbonate are disclosed. The processes use a water removal agent to tune the amount of disubstituted oxalate and/or disubstituted carbonate in the product mixture. One process includes contacting a cesium salt with one or more alcohols in the presence of an effective amount of a water removal agent under a carbon dioxide (CO2) atmosphere and reaction conditions sufficient to produce a composition that includes a disubstituted oxalate. Methanol can be used to produce dimethyl oxalate.
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Paragraph 0074
(2020/02/16)
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- CARBONATE DERIVATIVE PRODUCTION METHOD
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The objective of the present invention is to provide a method for producing a carbonate derivative in a safe and efficient manner. The method for producing a carbonate derivative according to the present invention is characterized in comprising irradiating light on a composition containing a C1-4 halogenated hydrocarbon having one or more kinds of halogen atoms selected from the group consisting of a chlorine atom, a bromine atom and an iodine atom, a nucleophilic functional group-containing compound and the specific base in the presence of oxygen.
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Paragraph 0099-0100
(2020/04/09)
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- Method for preparing carbonate by decarbonylation of oxalate (by machine translation)
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The invention relates to a method, for preparing carbonate by decarbonylation of oxalate, which mainly solves the problems, in the prior art that the reaction condition is low, catalyst activity is low. and the catalyst is easy to deactivate in the step; of preparing carbonate . The catalyst comprises 50-90 parts of polystyrene resin and 10-50 parts of quaternary phosphonium salt PR in parts by weight. 1 R2 R3 X, Based on the total weight of the polystyrene resin and the quaternary phosphonium salt ; R. 1 , R2 And R3 Aryl or alkyl C, respectivelya Hb , a＝2-10,b＝4-20;X Is F, Cl, Br or I. (by machine translation)
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Paragraph 0044-0057
(2020/03/12)
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- Method for preparing carbonate from oxalate
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The invention relates to a method for preparing carbonate from oxalate. A purpose of the invention is mainly to solve the problems of harsh reaction conditions, low catalyst activity and easy catalystdeactivation in the prior art. The method comprises: making oxalate contact a catalyst to prepare carbonate, wherein the catalyst comprises, by weight, 70-90 parts of a polystyrene resin and 10-30 parts of an imidazole salt C3H3N2RX based on the total parts by weight of the polystyrene resin and the imidazole salt, R is alkyl CaHb, a is equal to 1-10, and b is equal to 3-20, and X is F, Cl, Br orI.
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Paragraph 0044-0057
(2020/03/12)
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- Direct transformation of silica from natural resources to form tetramethoxysilane
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A simple and practical method for direct synthesis of tetramethoxysilane (TMOS) from silica (SiO2) and methanol was achieved using a base catalyst and acetal as a dehydrant under carbon dioxide (CO2). The production of TMOS was strongly influenced by the kind of the acetal used, with 2,2-dimeth-oxypropane identified as the most effective dehydrant. We observed that the acetal used enabled the production of a high yield of dimethyl carbonate (DMC), which promoted the TMOS production. DMC is an intermediate product from the reaction of CO2 and methanol, which supported the SiO2 depolymerization process. When the reaction is conducted with 2,2-dimethoxypropane at 260 °C for 24 h, TMOS can be produced in up to 59percent yield. For practical applications, the TMOS synthesis has been developed on a 250 mL and 1 L-scale reaction with constant yield (>50percent) from various silica resources.
- Putro, Wahyu S.,Fukaya, Keisuke,Choi, Jun-Chul,Choi, Seong Jib,Horikoshi, Toshio,Sato, Kazuhiko,Fukaya, Norihisa
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p. 958 - 962
(2020/09/04)
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- Room temperature and normal pressure preparation method of organic carbonate
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The invention relates to the technical field of organic synthesis, and provides a room temperature and normal pressure preparation method of organic carbonate. The method comprises the following steps: introducing carbon dioxide into an imidazole ionic liquid to obtain a mixture; mixing the obtained mixture with alcohol and halogenated hydrocarbon, and carrying out addition-substitution reactionsto obtain organic carbonate. The whole reaction process is carried out at a room temperature under a normal pressure. The activation energy of the reaction is reduced by using imidazole ionic liquid and halogenated hydrocarbon, and finally, organic carbonate is prepared from CO2 at a room temperature under a normal pressure.
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Paragraph 0061-0063
(2020/07/15)
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- Catalyst capable of realizing preparation of dimethyl carbonate through selective oxidation of methylal, and preparation method and applications thereof
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The invention discloses a catalyst capable of realizing preparation of dimethyl carbonate through selective oxidation of methylal, and a preparation method and applications thereof. According to the preparation method, a high specific surface area porous carrier is loaded with Fe-g-C3N4 as an active component; the obtained catalyst is composed of 18 to 35% of Fe-g-C3N4 and 65 to 82% of the porouscarrier; in the active component Fe-g-C3N4, the mass ratio of iron element to g-C3N4 mFe:mg-C3N4 is controlled to be 1:2-10. The preparation method is simple; the recycling performance is excellent; the raw materials are cheap and easily available; the preparation method is simple, is friendly to the environment, is capable of avoiding defects in the prior art, and is promising in application prospect.
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Paragraph 0010; 0020-0022; 0024; 0026; 0028; 0030; 0032
(2019/01/22)
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- Catalyst design criteria and fundamental limitations in the electrochemical synthesis of dimethyl carbonate
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Dimethyl carbonate is an environmentally friendly precursor in various chemical reactions and is currently synthesized by hazardous processes. An electrocatalytic approach could result in a process abiding to the principles of Green Chemistry. Herein we demonstrate how density functional theory (DFT) calculations and experiment advance our understanding of electrocatalytic production of chemicals. Using density functional theory, we form design criteria for dimethyl carbonate electrosynthesis on metallic surfaces. The criteria are based on adsorption free energies of reactants and reaction energies of possible products. The design criteria allow us to identify copper as an interesting candidate for the electrode material as it is classified as being selective to dimethyl carbonate and requires ≈1 V lower potential than a gold electrode. By further addressing electrode stability copper was found to dissolve and produce copper-carbonyl species which lead to dimethyl carbonate as a consequence of a reaction in the solution, therefore not occurring by surface electrocatalysis. This shows that the design criteria presented herein are necessary but not sufficient requirements that the ideal electrode should satisfy.
- ?ari?, Manuel,Davies, Bethan Jane Venceslau,Schj?dt, Niels Christian,Dahl, S?ren,Moses, Poul Georg,Escudero-Escribano, María,Arenz, Matthias,Rossmeisl, Jan
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p. 6200 - 6209
(2019/11/20)
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- Electrochemically Generated Copper Carbonyl for Selective Dimethyl Carbonate Synthesis
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Development of electrochemical synthesis routes for high-value chemicals could pave the way for a sustainable chemical industry based on electricity. Herein, the electrochemical synthesis of the industrially relevant and environmentally benign reagent, dimethyl carbonate (DMC), is investigated. By utilizing a combination of electrochemical techniques, in situ infrared spectroscopy, and headspace-gas chromatography-mass spectrometry we show production and spectroelectrochemical evidence for the synthesis of DMC via an electrochemically generated copper carbonyl species. The formation of the copper carbonyl has close to 100% current efficiency, in the applied potential range of 0.1-0.4 V vs SCE. Subsequent formation of DMC occurs with a slow reaction time on the order of 30-40 days. Relative to potential coproducts, the reaction is highly selective for DMC. Optimization of the reaction may lead to a viable method of DMC production.
- Davies, Bethan J. V.,?ari?, Manuel,Figueiredo, Marta C.,Schj?dt, Niels C.,Dahl, S?ren,Moses, Poul Georg,Escudero-Escribano, María,Arenz, Matthias,Rossmeisl, Jan
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p. 859 - 866
(2019/02/10)
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- METHOD FOR PREPARING DIALKYL CARBONATE
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A method for preparing dialkyl carbonate is provided. The method includes mixing an alcohol compound, carbon dioxide and a catalyst to form a mixing solution, and adding organic acid to the mixing solution to carry out the synthesis of dialkyl carbonate.
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Paragraph 0024-0065; 0084-0122
(2019/08/08)
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- Method of manufacturing Dialkyl carbonate using carbon dioxide
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In the embodiment of the present invention consists of a carbon dioxide using the d alkyl car this [thu [thu] which it sees a manufacturing method is provided other [...] number one, alcohol, imidazolium cation and bicarbonate mixing negative catalyst and bases the solvent to form a mixture, said mixture by mixing said reactants including injecting carbon dioxide for generating an agitating the manufacturing method characterized in that the d alkyl car this [thu [thu] which it sees a number [...] substrate. (by machine translation)
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Paragraph 0073-0079; 0088; 0092-0119; 0124-0129; 0133-0147
(2019/08/12)
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- Synthesis of dimethyl carbonate from methanol and urea over zinc-strontia mixed oxide catalysts
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A series of ZnO-SrO mixed oxide catalysts were prepared by co-precipitation with different compositions and tested for dimethyl carbonate synthesis from urea and methanol. The catalysts were characterized by BET surface area, XRD, NH3-TPD and CO2-TPD. The catalyst with 1:1 mol ratio exhibited high DMC yield of 35%. The uniform distributions of moderate to strong basic sites along with considerable number of acidic sites are accountable for high activity. Different reaction parameters were also screened and best possible conditions were established. The catalyst was easily recovered and reused with consistent activity.
- D., Dhana Lakshmi,B., Srinivasa Rao,Lingaiah
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- Fabrication of solid strong bases at decreased temperature by doping low-valence Cr3+ into supports
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Mesoporous solid strong bases (MSSBs) have gained tremendous research interest as environment-friendly catalysts in various reactions. Nevertheless, the fabrication of MSSBs remains an enormous challenge because a pretty high temperature is needed to produce strong basicity in traditional mesoporous materials. Here, we report a strategy of endowing supports with reducibility (ESWR) by doping low-valence Cr3+ into mesoporous Al2O3. The base precursors NaNO3 can be converted to basic sites completely at the low temperature of 400 °C via the ESWR strategy. The examination of activation mechanism indicates that the redox interaction between Cr3+ and NaNO3 is responsible for the low-temperature conversion of supported NaNO3. As a result, MSSBs were synthesized successfully by the ESWR strategy, showing strong basicity and remarkable catalytic activity in the transesterification reaction. The catalytic activity is obviously higher than typical solid bases like MgO as well as a variety of reported basic catalysts.
- Peng, Song-Song,Wu, Ju-Kang,Peng, An-Zhong,Li, Yu-Xia,Gu, Chen,Yue, Ming-Bo,Liu, Xiao-Qin,Sun, Lin-Bing
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- Improved Synthesis of Unsymmetrical Carbonate Derivatives Using Calcium Salts
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An effective synthetic method for unsymmetrical carbonate species has been developed. Calcium oxide and calcium hydroxide were found to be highly effective for this reaction, affording unsymmetrical carbonates in high yield and purity. Calcium chloride, which is a coproduct, serves as a water scavenger that can be easily removed. Additional drying processes and complicated purification steps are not necessary in this reaction. This improved process is important in terms of green sustainable chemistry principles.
- Hamada, Tomohito,Okada, Michiaki,Yamauchi, Akiyoshi,Kishikawa, Yosuke
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p. 667 - 673
(2019/04/25)
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- Identifying the components of the solid–electrolyte interphase in Li-ion batteries
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The importance of the solid–electrolyte interphase (SEI) for reversible operation of Li-ion batteries has been well established, but the understanding of its chemistry remains incomplete. The current consensus on the identity of the major organic SEI component is that it consists of lithium ethylene di-carbonate (LEDC), which is thought to have high Li-ion conductivity, but low electronic conductivity (to protect the Li/C electrode). Here, we report on the synthesis and structural and spectroscopic characterizations of authentic LEDC and lithium ethylene mono-carbonate (LEMC). Direct comparisons of the SEI grown on graphite anodes suggest that LEMC, instead of LEDC, is likely to be the major SEI component. Single-crystal X-ray diffraction studies on LEMC and lithium methyl carbonate (LMC) reveal unusual layered structures and Li+ coordination environments. LEMC has Li+ conductivities of >1 × 10?6 S cm?1, while LEDC is almost an ionic insulator. The complex interconversions and equilibria of LMC, LEMC and LEDC in dimethyl sulfoxide solutions are also investigated.
- Wang, Luning,Menakath, Anjali,Han, Fudong,Wang, Yi,Zavalij, Peter Y.,Gaskell, Karen J.,Borodin, Oleg,Iuga, Dinu,Brown, Steven P.,Wang, Chunsheng,Xu, Kang,Eichhorn, Bryan W.
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p. 789 - 796
(2019/08/22)
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- Significant Decrease in Activation Temperature for the Generation of Strong Basicity: A Strategy of Endowing Supports with Reducibility
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Mesoporous solid strong bases are quite attractive due to their good catalytic performance for applications as environmentally friendly catalysts in various reactions. However, pretty harsh conditions are usually compulsory for the fabrication of strong basicity by using traditional thermal activation (e.g., 700 °C for the activation of base precursor KNO3 supported on mesoporous Al2O3). This is energy intensive and harmful to the mesoporous structure. In this study, we report a strategy of endowing supports with reducibility (ESWR) by doping low-valence Cr3+ into mesoporous Al2O3, so that the activation temperature for basicity generation is decreased significantly. Fascinatingly, KNO3 on mesoporous Al2O3 can be motivated to basic sites completely at the temperature of 400 °C via the ESWR strategy, which is much lower than the conventional thermal activation (700 °C). We have demonstrated that the redox reciprocity between KNO3 and Cr3+ is responsible for the lowerature conversion, and Cr6+ is formed quantitatively as the oxidation product. The obtained solid bases possessing ordered mesostructure and strong basicity provide promising candidates for base-catalyzed synthesis of dimethyl carbonate via transesterification. The catalytic activity is obviously higher than a typical solid base like MgO as well as a series of reported basic catalysts containing alkali metal and alkaline-earth metal oxides.
- Peng, Song-Song,Lu, Jie,Li, Tian-Tian,Tan, Peng,Gu, Chen,Wu, Zheng-Ying,Liu, Xiao-Qin,Sun, Lin-Bing
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p. 8003 - 8011
(2019/06/17)
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- Method for synthesizing dimethyl carbonate under catalysis action of ionic liquid
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The invention discloses a method for synthesizing dimethyl carbonate under the catalysis action of an ionic liquid. The bifunctional ionic liquid is adopted as a catalyst, a transesterification reaction is performed between ethylene carbonate and methanol, wherein when the use amount of the catalyst is 0.5-10 mol% of ethylene carbonate, the molar ratio of ethylene carbonate to methanol is 1:(5-30), the reaction temperature is 40-70 DEG C, and the reaction time is 2-12 h, so that dimethyl carbonate and ethylene glycol are synthesized with a high conversion rate and high selectivity. The methodhas the following advantages: (1) the bifunctional ionic liquid adopted as the catalyst has the effect of a homogeneous reaction and the characteristic of a heterogeneous catalyst, the shortcomings ofconventional solid catalysts and the homogeneous catalysts are overcome, and high catalytic activity, easy separation, recyclability and no pollution to the environment are achieved; (2) since the bifunctional ionic liquid is applied to the reaction system, reactants can be activated under the synergistic action of anions and cations of the catalyst, higher catalytic activity is achieved, and synthesis operation of the catalyst is simple and easy.
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Paragraph 0023; 0024; 0025; 0026; 0027; 0028; 0029-0036
(2019/05/15)
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- Coupling of CH 3 OH and CO 2 with 2-cyanopyridine for enhanced yields of dimethyl carbonate over ZnO – CeO 2 catalyst
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Abstract: The present work is aimed to produce dimethyl carbonate by coupling of CH 3OH and CO 2 with 2-cyanopyridine over ZnO–CeO 2 catalysts prepared by co-precipitation method. These catalysts were characterized by XRD, TEM, UV-Vis DRS, BET surface area, CO 2 and NH 3-TPD techniques and applied for the titled reaction. Among the investigated catalysts 10ZnO–90CeO 2 catalyst with CeO 2 crystallite size 8.0?nm exhibited 96% conversion of methanol with 99% selectivity to dimethyl carbonate. The superior catalytic activity is a unified effect of crystalline size of CeO 2 and presence of an optimum number of acidic and basic sites. This protocol offers enhanced conversion of methanol with the simultaneous conversion of 2-cyanopyridine into 2-picolinamide by removing water molecules formed in the reaction. Graphic Abstract: Incorporation of ZnO with CeO 2 enhanced the number of active sites, i.e., acidic and basic sites due to synergetic effect between ZnO and CeO 2. The role of 2-cyano pyridine is to act as a dehydrating agent for the removal of H 2O. [Figure not available: see fulltext.]
- Challa, Prathap,Venkata Rao,Nagaiah,Nagu,David Raju,Rama Rao
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- Monomeric alkoxide and alkylcarbonate complexes of nickel and palladium stabilized with the iPrPCP pincer ligand: A model for the catalytic carboxylation of alcohols to alkyl carbonates
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Monomeric alkoxo complexes of the type [(iPrPCP)M-OR] (M = Ni or Pd; R = Me, Et, CH2CH2OH; iPrPCP = 2,6-bis(diisopropylphosphino)phenyl) react rapidly with CO2 to afford the corresponding alkylcarbonates [(iPrPCP)M-OCOOR]. We have investigated the reactions of these compounds as models for key steps of catalytic synthesis of organic carbonates from alcohols and CO2. The MOCO-OR linkage is kinetically labile, and readily exchanges the OR group with water or other alcohols (R′OH), to afford equilibrium mixtures containing ROH and [(iPrPCP)M-OCOOH] (bicarbonate) or [(iPrPCP)M-OCOOR′], respectively. However, [(iPrPCP)M-OCOOR] complexes are thermally stable and remain indefinitely stable in solution when these are kept in sealed vessels. The constants for the exchange equilibria have been interpreted, showing that CO2 insertion into M-O bonds is thermodynamically more favorable for M-OR than for M-OH. Alkylcarbonate complexes [(iPrPCP)M-OCOOR] fail to undergo nucleophilic attack by ROH to yield organic carbonates ROCOOR, either intermolecularly (using neat ROH solvent) or in intramolecular fashion (e.g., [(iPrPCP)M-OCOOCH2CH2OH]). In contrast, [(iPrPCP)M-OCOOMe] complexes react with a variety of electrophilic methylating reagents (MeX) to afford dimethylcarbonate and [(iPrPCP)M-X]. The reaction rates increase in the order X = OTs IMe ? OTf and Ni Pd. These findings suggest that a suitable catalyst design should combine basic and electrophilic alcohol activation sites in order to perform alkyl carbonate syntheses via direct alcohol carboxylation.
- Martínez-Prieto, Luis M.,Palma, Pilar,Cámpora, Juan
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p. 1351 - 1366
(2019/01/30)
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- Method for synthesizing propionate through ester-ester exchange path
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The invention provides a method for synthesizing propionate through an ester-ester exchange path and relates to a method for synthesizing the propionate. According to the method, reaction raw materials include, but are not limited to ethyl formate, propyl formate, butyl formate, ethyl acetate, propyl acetate, butyl acetate and the like; the method for synthesizing the propionate through an ester exchange one-step method is adopted. A catalyst comprises alkaline materials including ionic liquid, soluble strong base, solid base and the like respectively; the catalyst has the advantages of high catalysis efficiency and no pollution. By taking methyl propionate and ethyl acetate reaction as an example, KOH is used as the catalyst, the mol ratio of the raw materials is 1 to 1, the reaction temperature is 60 DEG C and the reaction time is 5 min; the conversion ratios of the methyl propionate and the ethyl acetate can reach 70 percent or more; products comprise ethyl propionate and the methylacetate. The whole reaction path has the characteristics of short synthetic route, simple technological flow and high yield and the catalyst is stable, does not become inactive and can be repeatedlyutilized.
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Paragraph 0030-0031
(2019/04/04)
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- Synthesis of dimethyl carbonate from CO2 and methanol over CeO2: Role of copper as dopant and the use of methyl trichloroacetate as dehydrating agent
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The effect of copper as dopant on ceria (CeO2) was investigated in the direct synthesis of dimethyl carbonate (DMC) from CO2 and methanol. Ceria with different copper loadings (0.02 and 0.5 wt%) was synthesized using the dry impregnation method and characterized by H2-TPR, XRD, EPR, UV–VIS/DRS, acid-base properties and N2 physisorption. CeO2 with 0.02 wt% of Cu showed the highest catalytic activity and selectivity to DMC, mostly due to its basic sites, associated with the presence of oxygen vacancies. Higher Cu concentration (0.5 wt%) promotes dehydrogenation, favoring the formation of methyl formate as the main product. Pure CeO2 also produced dimethoxymethane as by-product. To circumvent the thermodynamic limitations of the reaction, methyl trichloroacetate was tested as dehydrating agent, showing superior performance than 2-cyanopyridine, due to its higher reactivity toward hydrolysis.
- Marciniak, Aryane A.,Alves, Odivaldo C.,Appel, Lucia G.,Mota, Claudio J.A.
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- Greener synthesis of dimethyl carbonate from carbon dioxide and methanol using a tunable ionic liquid catalyst
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Several types of ionic liquids (ILs) performance towards dimethyl carbonate (DMC) synthesis using cheap reactant (methanol) and waste CO2 which is abundantly available in the environment are discussed. We synthesized ILs with cheap raw materials such as ethylene glycol. The main aim of this study is to synthesize efficient catalysts for the production of profitable fuel additives. ILs show high thermal stability, less viscosity, and low vapor pressure. In addition, some ILs have high CO2 absorption capacity due to moderate acid-base properties. These ILs reversibly capture more CO2 which is more efficient towards mass transport of methanol at optimum reaction conditions which enhance the DMC yield. This catalytic system is easily reusable for several reactions without decreased performance under the same reaction conditions. These reaction conditions had an effect on the synthesis of DMC. Temperature, pressure, IL loading, and IL/DMAP ratio were fine tuned. We propose a mechanism which the reaction may follow. The synthesized ILs required moderate reaction conditions and reduce waste gases (CO2) from the environments as they have high CO2 absorption capacity compared to the metal oxide catalyst. Therefore, this catalytic system helps and gives new direction to synthesize new catalyst for other application.
- Pawar, Atul A.,Chaugule, Avinash A.,Kim, Hern
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p. 1252 - 1265
(2020/02/06)
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- Method for Enzymatic Method for Glycerol Carbonate Preparation from Carbon dioxide
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The present invention relates to a method for manufacturing glycerol carbonate using enzymes from glycerol and carbon dioxide, wherein the method, by manufacturing glycerol carbonate from carbon dioxide and glycerol in an effort to reduce a generation amount, has an effect of manufacturing glycerol carbonate which can not only reduce carbon dioxide and glycerol, but also has high value.(AA) Carbonic anhydrase(BB) Catalyst(C1,C2) LipaseCOPYRIGHT KIPO 2020
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Paragraph 0125-0128
(2020/03/24)
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- Photolysis of Tp′Rh(CNneopentyl)(PhNCNneopentyl) in the presence of ketones and esters: Kinetic and thermodynamic selectivity for activation of different aliphatic C-H bonds
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The active fragment [Tp′Rh(CNneopentyl)], generated from the precursor Tp′Rh(CNneopentyl)(PhNCNneopentyl), underwent oxidative addition of substituted ketones and esters resulting in Tp′Rh(CNneopentyl)(R)(H) complexes (Tp′ = tris-(3,5-dimethylpyrazolyl)borate). These C-H activated complexes underwent reductive elimination at varying temperatures (24-70 °C) in C6D6 or C6D12. Using previously established kinetic techniques, the relative Rh-C bond strengths were calculated. Analysis of the relative Rh-C bond strengths vs. C-H bond strengths shows a linear correlation with slope RM-C/C-H = 1.22 (12). In general, α-substituents increase the relative Rh-C bond strengths compared to the C-H bond that is broken.
- Jones, William D.,Parsons, Astrid M.
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supporting information
p. 10945 - 10952
(2019/08/01)
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- Method for preparing dialkyl carbonate by alcoholysis of urea
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The invention relates to a method for preparing dialkyl carbonate by alcoholysis of urea, belonging to the field of chemical synthesis. More specifically, the invention relates to preparation of dialkyl carbonate. The method comprises the following step: subjecting urea and alkyl monohydric alcohol to a reflux reaction under stirring for 6 to 30 hours under the condition of normal pressure or reduced pressure at a reaction temperature of 70 to 150 DEG C by using one or more selected from the group consisting of metal magnesium, calcium, aluminum, chromium, manganese, iron, cobalt, nickel, copper or zinc as a main catalyst and one or more compounds containing donor atom nitrogen, phosphorus, oxygen or sulfur as an auxiliary catalyst so as to prepare the dialkyl carbonate. The preparation method provided by the invention has the following advantages: the dialkyl carbonate is prepared with high selectivity and high yield at a low reaction temperature under the condition of normal pressureor reduced pressure; simple operation, high safety and low cost are achieved in the processing process; and good industrial application prospects are obtained.
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Paragraph 0043
(2018/09/08)
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