- The use of inorganic Al-HMS as a support for NiMoW sulfide HDS catalysts
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Inorganic hexagonal mesoporous silica (HMS) and aluminum modified HMS materials (Al-HMS) were prepared and used as supports of transition metal sulfide hydrodesulfurization (HDS) catalysts based on nickel, molybdenum, and tungsten as active phase. The samples were characterized with XRD, HRTEM, TPD, N2 physisorption and UV–Vis. The catalytic activity of the trimetallic catalysts was performed in the HDS of dibenzothiophene (DBT). When Al was incorporated into the inorganic support, important changes and effects were observed on the physicochemical properties. On the other hand, the incorporation of Al into the HMS led to a decrease in the reaction rate (k) and a trend toward a direct path of desulfurization was observed for all materials.
- Alonso-Nú?ez, G.,Huirache-Acu?a, R.,Maya-Yescas, R.,Pawelec, B.,Rivera-Mu?oz, E. M.,Vázquez, P. J.,Zepeda, T. A.
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- Bulk hydrotreating MonW12-nS2 catalysts based on SiMonW12-n heteropolyacids prepared by alumina elimination method
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A series of unsupported mono- and bimetallic MonW12-nS2 catalysts were synthesized by alumina elimination from supported MonW12-nS2/Al2O3 samples using acid etching. Alumina supported catalysts have been in turn prepared by using monometallic H4SiMo12O40 and H4SiW12O40 heteropolyacids (HPAs), their mixture with Mo/W atomic ratio equal to 1/11 and 3/9, and mixed bimetallic H4SiMo1W11O40 and H4SiMo3W9O40 HPAs. All catalysts were characterized by N2 adsorption, temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), time-of-flight secondary ion mass spectrometry (ToF-SIMS), extended X-ray absorption fine structure (EXAFS) spectroscopy and powder X-ray diffraction (XRD) and their performance were evaluated in simultaneous hydrodesulfurization (HDS) of dibenzothiophene (DBT) and hydrogenation (HYD) of naphthalene. The etching process led to a successful removal of all the support and of the partially sulfided species, with sulfidation degrees of both Mo and W above 90 % on the final bulk solids. The active phase also underwent a rearrangement, as higher average length and stacking were measured on the bulk catalysts than on the original supported ones. Mixed MoWS2 phase was evidenced in all solids, prepared from mixed HPAs (MonW12-nS2) or from the mixture of monometallic HPAs (RefMonW12-nS2), by EXAFS and ToF-SIMS, with however a larger quantity on the MoW solids. It seems that the mixed MoWS2 phase observed on the supported MoW catalysts is maintained through the etching process, while on RefMonW12-nS2 the mixed phase, observed in a much lesser extent in the corresponding supported catalyst, could result from the aggregation of the monometallic slabs. MonW12-nS2 catalysts were found more effective than the monometallic catalysts and than the corresponding RefMonW12-nS2, in both dibenzothiophene hydrodesulfurization and naphthalene hydrogenation, which was related to the presence of the mixed phase maintained through the etching of the support.
- Kokliukhin,Nikulshina,Mozhaev,Lancelot,Lamonier,Nuns,Blanchard,Bugaev,Nikulshin
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- A feasible approach to the synthesis of nickel phosphide for hydrodesulfurization
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In this paper, we propose a simple and feasible method for synthesizing bulk and supported nickel phosphides from oxide precursors. The new approach uses a low hydrogen flow speed and is not affected by the heating rate. The results indicate that Ni2P can be synthesized at 600 °C from its oxide precursors with a mole ratio of Ni/P = 2/1. The hydrodesulfurization activity results indicate that the direct-reduction method shows excellent performance in the synthesis of supported catalysts.
- Guan, Qingxin,Cheng, Xun,Li, Rongguan,Li, Wei
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- Comparative activity of Ni-W and Co-Mo sulfides using transition metal oxides as precursors in HDS reaction of DBT
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Unsupported catalysts based on nickel, cobalt, tungsten, and molybdenum were prepared by sulphurization of Ni, Co, W, and Mo oxides. All catalysts were tested in hydrodesulphurization of dibenzothiophene reaction. The best activity was attained with a sample based on W (5.64 × 1016 molecules/s m2). The best selectivity for biphenyl (70.14 %) was achieved with Ni17S18. Materials were characterized by X-ray diffraction and surface area measurements. Graphical Abstract: Reaction network for hydrodesulphurization (HDS) of dibenzotiophene (DBT) by direct desulphurization pathway (DDS) and hydrogenating pathway (HYD) to produce biphenyl (BP) and cyclohexyl-benzene (CHB). nH2 = hydrogen excess at 3.378 MPa, dihydrodibenzotiophene (DHDBT), tetrahydrodibenzothiophene (THDBT), hexahydrodibenzothiophene (HHDBT), hydrogen sulphide (H2S). Ni 17S18 as a yield of 12.03 % THDBT, 17.83 % CHB, and 70.14 % BP.[Figure not available: see fulltext.]
- Quintana-Melgoza, Juan Manuel,Alonso-Nunez, Gabriel,Homero-Galvan, Donald,Avalos-Borja, Miguel
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- Iron(II) bipyridine complexes for the cross-coupling reaction of bromocyclohexane with phenylmagnesium bromide
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Three known iron(II) complexes bearing a bipyridine ligand, [FeCl2(bpy)2] (1), [FeCl2(bpy)]2 (2) and [FeCl2(dmbpy)] (3) (bpy?=?2,2′-bipyridine and dmbpy?=?6,6′-dimethyl-2,2′-bipyridine) were employed for the cross-coupling reaction of bromocyclohexane (4) with phenylmagnesium bromide (5). These complexes catalyzed the cross-coupling reaction. Among the three catalysts, complex 2 acted as an effective catalyst to afford the cross-coupled product phenylcyclohexane (6) in 92% yield. The X-ray crystal structure analyses of 2 and 3 were demonstrated.
- Matsubara, Yutaka,Yamaguchi, Takamichi,Hashimoto, Toru,Yamaguchi, Yoshitaka
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- Enhancement of biphenyl hydrogenation over gold catalysts supported on Fe-, Ce- and Ti-modified mesoporous silica (HMS)
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Mesoporous metallosilicates (HMS-M; M = Ce, Fe, Ti) were used as supports for the preparation of Au catalysts, and were tested in the liquid-phase hydrogenation of biphenyl at 5 MPa and 488 K. Irrespective of the support, uniformly dispersed Au nanoparticles in range 3.2-6.5 nm were obtained. The highest turn over frequency (TOF), expressed per surface Au atom, was achieved on the Au/HMS-Fe, furthermore this catalyst gave the highest selectivity to the most saturated compound (bicyclohexyl with the highest cetane number) by means of enhancing the second aromatic-ring hydrogenation. From the catalyst activity-structure correlation, the highest activity of the Au/HMS-Fe catalyst is linked with: (i) the higher ratio of positively charged metallic gold Auδ+/Si (XPS), and (ii) the higher stability of Au nanoparticles (HRTEM). A linear correlation between the activity (per gram of metal) of the catalysts and their ratio Auδ+/Si is observed; however, Au/HMS-Ce catalyst displays a different behaviour in terms of activity per gram of metal exposed caused by the fact that ceria is not incorporated in the framework.
- Castano, Pedro,Zepeda,Pawelec,Makkee, Michiel,Fierro
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- Visible-light-induced photocatalytic benzene/cyclohexane cross-coupling utilizing a ligand-to-metal charge transfer benzene complex adsorbed on titanium oxides
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The cross-coupling reaction of benzene and cyclohexane molecules proceeded selectively over Pd-modified titanium dioxide photocatalysts under visible light. A ligand-to-metal charge-transfer (LMCT) complex of benzene adsorbed on titanium oxide was proposed as the key species for the selective formation of the cross-coupling product.
- Yamamoto,Ohara,Yoshida
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- Hydrodesulfurization of Dibenzothiophene Catalyzed by Silica-Alumina Supported Anionic Molybdenum Carbonyl Complexes
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In hydrodesulfurization (HDS) of dibenzothiophene (DBT), the catalysts prepared from silica-alumina supported molybdenum compounds showed higher yields of biphenyl, cyclohexylbenzene and bicyclohexyl than conventional sulfided molibdena-alumina. Specifically, the catalysts derived from silica-alumina supported anionic molybdenum carbonyls gave the highest yields among silica-alumina supported ones.
- Ishihara, Atsushi,Shirouchi, Kenji,Kabe, Toshiaki
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- The selectivity of sulfided NiW/Al2O3 catalyst in the hydrodesulfurization of dibenzothiophene
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The hydrodesulfurization of petroleum residue is widely practiced and the need for a similar technology for coal-derived liquids is well recongnized. The selectivity of a sulfided NiW/Al2O3 catalyst for hydrodesulfurization has been studied at 300°C and 10.1 MPa total pressure. The presence of oxygen and sulfur compounds depressed the desulfurization of dibenzothiophene, but not the hydrogenation. The addition of large amounts of acridine improved the catalytic activity significantly for the desulfurization of dibenzothiophene to biphenyl while preventing hydrogenation.
- Nagai
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- On the oxidation state of iron in iron-mediated C-C couplings
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The nature of the active catalyst in iron-catalyzed C-C couplings has been under debate. In here, we study the couplings with aryl Grignard reagents, and clearly show that the active catalyst is an Fe(I) species. The Grignard alone can reduce the pre-catalyst to the Fe(I) state, and no further, as shown by quantification of product formation. Addition of the electrophile results in complete cross-coupling, validating the nature of the active catalyst. A computational study reveals that the active iron catalyst has a spin state of S = 3/2, high spin for Fe(I) but intermediate spin for Fe(III) complexes, even though the Fe(III) precatalyst salts have a high spin state (S = 5/2). The spin change occurs after the first transmetallation, when the strong ligand field of the aryl group raises the energy of one d-orbital, inducing an electron pairing event. All steps in the formation of an active cross-coupling catalyst are facile and strongly exergonic.
- Hedstr?m, Anna,Lindstedt, Erik,Norrby, Per-Ola
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- Synthesis and Reactivity of Manganese(II) Complexes Containing N-Heterocyclic Carbene Ligands
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A series of manganese(II) complexes containing aryl-substituted N-heterocyclic carbene (NHC) ligands have been synthesized and characterized. Chloride complexes of Mn(II) containing the NHC ligands 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) and 1,3-dimesitylimidazol-2-ylidene (IMes) were prepared in straightforward fashion by direct carbene addition to MnCl2(THF)1.6. These complexes exist as chloride-bridged dimers in solution of formula [Mn2Cl2(μ-Cl)2(NHC)2]. The monomeric complex [MnCl2(IMes)2] has also been prepared and structurally characterized, although NMR studies are consistent with facile dissociation of one of the IMes ligands in solution. [Mn2Cl2(μ-Cl)2(IPr)2] serves as a precursor to dimeric alkyl and aryl compounds of Mn(II) including [Mn2R2(μ-Cl)2(NHC)2] (R = Bn, o-tolyl, and Ph) and the bridging methyl complex [Mn2Me2(μ-Me)2(IPr)2]. Stoichiometric reactions of these hydrocarbyl species with bromocyclohexane demonstrate that they are not chemically competent in C-C coupling reactions involving alkyl electrophiles.
- Al-Afyouni, Malik H.,Krishnan, V. Mahesh,Arman, Hadi D.,Tonzetich, Zachary J.
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- Study of Hydrodesulfurization by the Use of 35S-Labeled Dibenzothiophene. 1. Hydrodesulfurization Mechanism on Sulfided Mo/Al2O3
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To estimate the behavior of sulfur on a hydrodesulfurization catalyst, 35S-labeled dibenzothiophene (DBT) was hydrodesulfurized on a sulfided Mo/Al2O3 in a fixed-bed pressurized flow reactor.After the hydrodesulfurization of DBT reached the steady state, the reactant solution of DBT was substituted for that of DBT at the same concentration of DBT.In this period, the radioactivities of unreacted DBT and formed H2S was monitored.The radioactivity of unreacted DBT reached the steady state immediately, while more time was needed for that of formed H2S to reach the steady state.This shows that the sulfur in dibenzothiophene was not directly released as hydrogen sulfide but initially accommodated on the catalyst.After the radioactivity of formed H2S reached the steady state, the reactant solution of DBT was substituted for that of DBT at the same concentration of DBT again.The behavior of sulfur on the catalyst was determined from the rates of an increase and decrease of formed H2S.It was found that the amount of labile sulfur, which could be calculated from the maximum amount of 35S accomodated on the catalyst, increased with increasing the reaction temperature and DBT concentration.In addition, it was suggested that the total sulfur on the catalyst sulfided under practical HDS reaction conditions existed as MoS1.92.
- Quian, Weihua,Ishihara, Atsushi,Ogawa, Shinji,Kabe, Toshiaki
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- One pot synthesis of NiMo-Al2O3 catalysts by solvent-free solid-state method for hydrodesulfurization
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A simple and solvent-free solid-state method was used to prepare NiMo-Al2O3 hydrodesulfurization (HDS) catalysts using Ni(NO3)2·6H2O, (NH4)6Mo7O24·4H2O, and AlCl3·6H2O as the solid raw materials and polyethylene glycol (PEG) as an additive. The effects of PEG addition on the precursor thermal decomposition, catalyst properties and dibenzothiophene (DBT) HDS activity were investigated. The as-prepared catalysts were characterized by nitrogen adsorption-desorption measurements, powder X-ray diffraction (XRD), thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), H2 temperature-programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The results showed that an increase in PEG addition dramatically increases specific surface area and pore volume of the catalyst, and improves Mo sulfidability and active MoS2 dispersion by blocking the aggregation of metals, and consequently increases the number of HDS active sites. However, excess PEG leads to the decrease in specific surface area and pore volume attributed to the metal sintering caused by the strong heat release during thermal decomposition. As a result, dibenzothiophene HDS activity enhanced with increasing PEG addition and peaked at NiMoAl-15 (15% weight ratio of PEG to alumina), which exhibited a significantly higher activity as compared to the NiMo/Al2O3 catalyst prepared by wetness co-impregnation.
- Yi, Xiaodong,Guo, Dongyun,Li, Pengyun,Lian, Xinyi,Xu, Yingrui,Dong, Yunyun,Lai, Weikun,Fang, Weiping
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- Elucidation of molybdenum-based catalysts using a radioisotope tracer method part 2? promotion effect of cobalt on molybdena/alumina catalyst
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Hydrodesulfurization (HDS) reactions of radioactive 35S-labelled dibenzothiophene were carried out over a series of cobalt-promoted molybdena/alumina catalysts at temperatures between 240 and 320°C and under 50 kg cm-2 pressure. HDS and hydrogenation (HYD) activities of Mo/Al2O3 catalysts were remarkably enhanced with the addition of cobalt, the maximum promotional effect occurring with a Co/Mo molar ratio of ca. 0.5. The amount of labile sulfur and the rate constant of sulfur exchange increased significantly with the addition of cobalt, indicating that cobalt makes the sulfur more mobile and that the active phases in the promoted catalysts are different from that in the unpromoted catalyst. The promoting effect of cobalt was thus attributed to the formation of more active sites. On the other hand, the amount of labile sulfur increased linearly with the Co/Mo ratio up to ca. 0.5 whereas the rate constant of sulfur exchange remained almost constant. Moreover, the enhancement in catalytic activity did not change significantly with the cobalt content. The increase in the catalytic activity with the cobalt content was thus ascribed to an increase in the number of the same active sites.
- Qian, Weihua,Ishihara, Atsushi,Okoshi, Yuzo,Nakakami, Waka,Godo, Masazumi,Kabe, Toshiaki
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- Hydrogenation of Biphenyl Using a Hydrogen Storage Alloy as a Hydrogenation Reagent
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A detailed investigation of the hydrogenation reaction of biphenyl with MmNi3.5Co0.7Al0.8H4.2 [Mm: mixture of La, Ce, Pr, and Nd (30 : 52 : 5 : 13 wt ratio)] to give either cyclohexylbenzene or bicyclohexyl was performed. Time profiles of the amounts of hydrogen evolved from the alloy and that introduced into biphenyl during the reaction were measured; it was suggested that the hydrogen absorbed by the alloy could predominantly react with the substrate, and the hydrogen released into the gas phase played only a minor role in the reaction. The deuteration of biphenyl with the deuterated alloy, MmNi3.5Co0.8Al0.8D3.5, was also examined; a GC-MS analysis of the reaction mixture indicated that a H-D exchange between the hydrogen in the substrate and the deuterium in the alloy took place as a parallel reaction to hydrogenation of the aromatic rings, and, as a result, the product cyclohexylbenzene appeared to contain 3-9 deuterium atoms.
- Nakagawa, Shin-Ichi,Murata, Satoru,Nomura, Masakatsu,Sakai, Tetsuo
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- A new approach to synthesize supported ruthenium phosphides for hydrodesulfurization
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Supported noble metal ruthenium phosphides were synthesized by one-step H2-thermal treatment method using triphenylphosphine (TPP) as phosphorus sources at low temperatures. Two phosphides RuP and Ru2P can be prepared by this method via varying the molar ratio of metal salt and TPP. The as-prepared phosphides were characterized by X-ray powder diffraction (XRD), low-temperature N2 adsorption, CO chemisorption and transmission electronic microscopy (TEM). The supported ruthenium phosphides prepared by new method and conventional method together with contradistinctive metallic ruthenium were evaluated in hydrodesulfurization (HDS) of dibenzothiophene (DBT). The catalytic results showed that metal-rich Ru2P was the better active phase for HDS than RuP and metal Ru. Besides this, ruthenium phosphide catalyst prepared by new method exhibited superior HDS activity to that prepared by conventional method.
- Wang, Qingfang,Wang, Zhiqiang,Yin, Xiaoqian,Zhou, Linxi,Zhang, Minghui
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- Phosphotungstic acid encapsulated in USY zeolite as catalysts for the synthesis of cyclohexylbenzene
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Abstract: In this work, a new type of catalyst, USY-HPW, was successfully prepared by encapsulating phosphotungstic acid (HPW) into ultra-stable Y zeolite (USY). The obtained catalyst USY-HPW was characterized by various techniques including N2 adsorption/desorption isotherms, XRD, SEM, TG-DSC, XPS, NH3-TPD, FT-IR, Py-IR. The catalytic properties of USY-HPW were evaluated by using a model alkylation reaction of benzene with cyclohexene to form cyclohexylbenzene. The conversion rate of cyclohexene can reach as high as 99.99%. Compared with USY alone, USY-HPW displayed markedly improved selectivity and yield for the target product of cyclohexylbenzene, ca. 5.41% and 8.73%, respectively. Besides, reusability tests indicated the high durability USY-HPW as the yield of cyclohexylbenzene can still reach to 83.50% after eight runs. All these results demonstrate that USY-HPW catalyst has good performances and holds good potential in acid catalyzed organic chemistry. Graphical abstract: [Figure not available: see fulltext.].
- Yang, Yufei,You, Yue,Wu, Junyan,Feng, Junbo,Zhang, Yadong
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- Activation of Lewis acid catalysts in the presence of an organic salt containing a non-coordinating anion: Its origin and application potential
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In the presence of a soluble organic salt containing non-coordinating anion (e.g., [bmim][SbF6] or [NR4][SbF6]), the catalytic activity of Lewis acid (MXn) was dramatically enhanced due to the anion exchange between the Lewis acid and organic salt. The Royal Society of Chemistry.
- Kim, Jin Hong,Lee, Ji Woong,Shin, Ueon Sang,Lee, Jin Yong,Lee, Sang-Gi,Song, Choong Eui
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- Organic reaction in water. Part 2. A new method for dechlorination of chlorobiphenyls using a Raney Ni-Al alloy in dilute aqueous alkaline solution
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Use of a Raney Ni-Al alloy in dilute aqueous alkaline gave rise to strong reducing power and chlorobiphenyls were reduced easily to biphenyl and/or phenylcyclohexane, respectively, without any organic solvents.
- Liu, Guo-Bin,Tsukinoki, Takehito,Kanda, Tadashige,Mitoma, Yoshiharu,Tashiro, Masashi
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- Highly active CoMo/Al (10) KIT-6 catalysts for HDS of DBT: Role of structure and aluminum heteroatom in the support matrix
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Herein we report the synthesis of CoMo catalysts for the hydrodesulfurization of dibenzothiophene reaction as a function of morphological effect and heteroatom substitution on KIT-6 supports. The interconnected pores of KIT-6 seem to play a vital role in the active catalyst preparation. The activity and direct desulfurization selectivity trends of the different catalysts resulted as follows: CoMo/Al(10)-KIT-6 > CoMo/KIT-6 > CoMo/γ-Al2O3. The improved catalytic activity and direct desulfurization selectivity are attributed to: (I) the high surface area and interconnected pores of KIT-6 which allow large quantities of nanosized (4 nm) active CoMoS species and (II) the aluminum deposition on the surface of KIT-6 that creates mild acidity on the support, facilitating the dispersion of these nano-sized CoMoS species. Finally, evidence of the Al incorporation into the silica Matrix is presented.
- Suresh,Pérez-Cabrera,Díaz de León,Zepeda,Alonso-Nú?ez,Moyado, S. Fuentes
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- Kinetic study of the radical azidation with sulfonyl azides
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Rate constants for the reaction between a secondary alkyl radical and two different sulfonyl azides were determined using bimolecular competing radical reactions. The rates of azidation were determined by competition with hydrogen atom transfer from tris(trimethylsilyl)silane ((TMS)3SiH) of the 4-phenylcyclohexyl radical. 3-Pyridinesulfonyl azide and trifluoromethanesulfonyl azide were found to have rate constants for azidation of 2×105M-1s-1 and 7×10 5M-1s-1 at 80°C, respectively.
- Weidner, Karin,Renaud, Philippe
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- Influence of Oxygen-Containing Compounds on Conversion and Selectivity of Dibenzotiophene and Naphthaline on Bulk and Supplied Co(Ni)MoS2 Catalysts
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The supported CoMoS2/Al2O3 and NiMoS2/Al2O3 catalysts were synthesized by impregnating of alumina to incipient wetness with aqueous solutions of 12-molybdophosphoric heteropoly acid and nickel or cobalt citrates. A bulk Ref-MoS2 catalyst was synthesized by thermal decomposition of ammonium tetratiomolybdate. The synthesized catalysts were examined by low temperature nitrogen adsorption and high resolution transmission electron microscopy. The catalytic properties were studied in the dibenzothiophene hydrodesulfurization and naphthalene hydrogenation in the presence of dodecanoic acid or guaiacol in a flow unit with a microreactor under hydrogen pressure. The bulk catalyst Ref-MoS2 had minimal sensitivity to dodecanoic acid and guaiacol during the combined hydrotreatment of dibenzothiophene and naphthalene. The effective adsorption constants of dodecanoic acid and guaiacol were calculated using the Langmuir-Hinshelwood model.
- Nikulshin, P. A.,Pimersin, A. A.,Salnikov, V. A.,Varakin, A. N.
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- Dehydrogenataion of Bicyclohexyl over Ni/Oxidized Sibunit Catalyst
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Abstract: The dehydrogenation of bicyclohexyl over single-component Ni-containing catalyst supported on oxidized Sibunit containing 3, 10, and 20 wt % of Ni is studied. The effect of addition of small amounts of Pt to Ni-catalysts on their activity with respect to hydrogen release is investigated. It is shown that the presence of nickel in the oxidized state facilitates electron transfer from platinum, reducing the dehydrogenation properties of two-component (Ni–Pt)-catalysts. It is established that the formation of a shell from the two metals on the surface of the material greatly slows the process of carbon support methanation.
- Kalenchuk,Leonov,Bogdan,Kustov
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- Molecular approach to prepare mixed MoW alumina supported hydrotreatment catalysts using H4SiMo: NW12- nO40 heteropolyacids
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H4[SiMonW12-nO40] heteropolyacids (HPAs) are interesting precursors for the preparation of alumina-supported hydrotreatment catalysts to introduce both metals simultaneously while maintaining a Mo-W nanoscale proximity. Two heteropolyacids (n = 1 and 3) have been synthesized and used for the first time to prepare hydrotreatment catalysts. Crystal structure refinement has been performed and evidenced the formation of β-H4[SiMo3W9O40] with three ordered Mo sites forming a face. The purity of the samples in aqueous solution has been determined by Raman spectroscopy and polarographic characterization. These heteropolyacids were then impregnated on alumina to prepare supported MoW-based catalysts. As references, catalysts with the same Mo/W ratios have been prepared using monometallic H4SiMo12O40 and H4SiW12O40 HPAs (mixture of these 2 HPAs in the impregnating solution). EXAFS characterization after drying performed simultaneously at the Mo K and W LIII edges indicates preservation of the mixed heteropolyanion SiMonW12-nO404- at the alumina surface even if partial decomposition to Keggin lacunary species could not be excluded and evidences the mixed MoW-S2 slab formation after sulfidation. Better catalytic hydrogenation properties for dibenzothiophene hydrodesulfurization and naphthalene hydrogenation have been obtained when using β-H4[SiMo3W9O40], which is explained by the formation of the mixed MoW-S2 active phase.
- Nikulshina,Blanchard,Mozhaev,Lancelot,Griboval-Constant,Fournier,Payen,Mentré,Briois,Nikulshin,Lamonier
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- Organocatalytic synthesis of (Het)biaryl scaffoldsviaphotoinduced intra/intermolecular C(sp2)-H arylation by 2-pyridone derivatives
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A uniqueN,O-bidentate ligand 6-oxo-1,6-dihydro-pyridone-2-carboxylic acid dimethylamide (L1) catalyzed direct C(sp2)-H (intra/intermolecular) arylation of unactivated arenes has been developed to expedite access to (Het)biaryl scaffolds under UV-irradiation at room temperature. The protocol tolerated diverse functional groups and substitution patterns, affording the target products in moderate to excellent yields. Mechanistic investigations were also carried out to better understand the reaction pathway. Furthermore, the synthetic applicability of this unified approach has been showcasedviathe construction of biologically relevant 4-quinolone, tricyclic lactam and sultam derivatives.
- Das, Tapas Kumar,Kundu, Mrinalkanti,Mondal, Biswajit,Ghosh, Prasanjit,Das, Sajal
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p. 208 - 218
(2021/12/29)
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- Catalyzed transfer hydrogenation by 2-propanol for highly selective PAHs reduction
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Catalytic hydrogenation of mono-, di- and trinuclear aromatic compounds has been studied under hydrogen transfer conditions at 150 °C and 82 °C in 2-PrOH as a hydrogen donor and with Raney nickel as a catalyst. In contrast to conjugated or condensed aromatic rings, isolated ones demonstrated low reactivity in transfer hydrogenation (TH) that can be used to increase the hydrogenation selectivity of the reaction. So, naphthalene and biphenyl are partially hydrogenated into tetralin and cyclohexylbenzene, respectively, with excellent conversion (≥ 96 %) and selectivity (≥ 98 %) for 5–6 h at 82 °C. Increasing the reaction temperature to 150 °C results expectedly in the hydrogenation of second aromatic ring, which occurs slowly enough. Only 8 % of decaline and 42 % of dicyclohexyl, correspondingly, were obtained after 5 h at 150 °C. At the same time, TH of trinuclear anthracene and phenanthrene at 150 °C resulted in the formation of deeper hydrogenated octahydro-anthracenes and -phenanthrenes, respectively.
- Philippov,Chibiryaev,Martyanov
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- Metallic Barium: A Versatile and Efficient Hydrogenation Catalyst
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Ba metal was activated by evaporation and cocondensation with heptane. This black powder is a highly active hydrogenation catalyst for the reduction of a variety of unactivated (non-conjugated) mono-, di- and tri-substituted alkenes, tetraphenylethylene, benzene, a number of polycyclic aromatic hydrocarbons, aldimines, ketimines and various pyridines. The performance of metallic Ba in hydrogenation catalysis tops that of the hitherto most active molecular group 2 metal catalysts. Depending on the substrate, two different catalytic cycles are proposed. A: a classical metal hydride cycle and B: the Ba metal cycle. The latter is proposed for substrates that are easily reduced by Ba0, that is, conjugated alkenes, alkynes, annulated rings, imines and pyridines. In addition, a mechanism in which Ba0 and BaH2 are both essential is discussed. DFT calculations on benzene hydrogenation with a simple model system (Ba/BaH2) confirm that the presence of metallic Ba has an accelerating effect.
- Stegner, Philipp,F?rber, Christian,Zenneck, Ulrich,Knüpfer, Christian,Eyselein, Jonathan,Wiesinger, Michael,Harder, Sjoerd
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supporting information
p. 4252 - 4258
(2020/12/22)
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- Effect of pre-activation treatment temperature on hydrodesulfurization catalytic activity of CoMoS/KIT-6
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Mesoporous silica-supported cobalt–molybdenum hydrodesulfurization catalysts have been prepared by wetness impregnation, drying and a thermal pre-treatment of impregnated support before activation. Characterization of materials was made by nitrogen adsorption, thermogravimetric analysis, Raman spectroscopy, TEM and XPS. Catalytic activity was determined by hydrodesulfurization of dibenzothiophene (DBT). The results indicate that the thermal pre-treatment carried out at the lower temperature allows the formation of smaller and less stacked active phase structures, with a higher amount of CoMoS phase.
- Beltrán, Karen A.,Alvarez-Contreras, Lorena,Delgado, Anabel D.,Leyva-Porras, César C.,Aguilar-Elguezabal, Alfredo
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p. 106 - 115
(2019/11/26)
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- Novel Molybdenite-Based Nanopowder Catalysts for Hydrodesulfurization
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Abstract: Novel bulk single-component sulfide catalysts were prepared under theconditions of solid-phase dispersion of МoS2 molybdeniteat various mechanical treatment times and various amounts of polar and nonpolarliquid microadditives. The chemical degradation of the samples in the air wasfound to lead to the formation of surface sulfate anions that shieldcatalytically active Mo sites. Indirect correlations of the hydrodesulfurizationability of MoS2 powders with the concentration of sulfateanions on their surface, and with the aqueous pH in the powder suspensions,including the dielectric permittivity of the organic dopants, can serve asreference indicators of high catalytic activity in the model reaction ofdibenzothiophene hydrogenolysis. The study identified the most active sampleable to run for an extended time during multiple cycles without losing itscatalytic properties. Also, the paper discusses the dibenzothiophene conversionroutes, the product composition, the probable structure of active sites in thecatalysts, and the desulfurization degree of diesel fuel components. [Figure not available: see fulltext.]
- Fedushchak,Uimin,Maikov,Akimov,Zhuravkov,Vosmerikov,Prosvirin,Velichkina,Stepanov,Kogan
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p. 794 - 805
(2021/07/14)
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- Synergy effect of boron and cobalt in B2O3-SBA-15-(Co)Mo catalyst for efficient hydrodesulfurization of liquid fuels
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The contributory effect of surface acidity is significant to desulfurize heavy recalcitrant organosulfur compounds effectively. This research explores the synergistic effect of boron and cobalt in CoMoS supported on B2O3-SBA-15 for ultradeep hydrodesulfurization (HDS) of DBT and MDBT in the model and diesel fuel, respectively. The catalysts prepared consisting of SBA-15-(Co)Mo, representing (SM and SMC) and B2O3-SBA-15-(Co)Mo for BSM and BSMC, were fully characterized to gain insight into the structural activity concerning the nature of the fuel and the organosulfur compound employed. The incorporation of boron into the mesoporous framework of SBA-15 improves the surface characteristics, viz. surface acidity, support metal interaction and textural properties, necessary for efficient catalytic HDS reaction. The catalysts BSM and BSMC outperformed their analogous catalysts SM and SMC. The catalytic efficiency of BSMC is outstanding and capable of desulfurizing diesel fuel (1000 ppmw-S) containing a more complex matrix with a 90% conversion of methyldibenzothiophene (MDBT). BSMC possessed favorable and lower activation energy (Ea) of 77.11 kJ mol?1 than other catalysts and can be used as a commercial catalyst for ultradeep desulfurization of real fuel. Graphic abstract: [Figure not available: see fulltext.].
- Ganiyu, Saheed A.
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p. 3751 - 3768
(2021/05/11)
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- Indium Tribromide-Catalysed Transfer-Hydrogenation: Expanding the Scope of the Hydrogenation and of the Regiodivergent DH or HD Addition to Alkenes
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The transfer-hydrogenation as well as the regioselective and regiodivergent addition of H?D from regiospecific deuterated dihydroaromatic compounds to a variety of 1,1-di- and trisubstituted alkenes was realised with InBr3 in dichloro(m)ethane. In comparison with the previously reported BF3?Et2O-catalysed process, electron-deficient aryl-substituents can be applied reliably and thereby several restrictions could be lifted, and new types of substrates could be transformed successfully in hydrodeuterogenation as well as deuterohydrogenation transfer-hydrogenation reactions.
- Li, Luomo,Hilt, Gerhard
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supporting information
p. 11221 - 11225
(2021/06/25)
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- Ligand-enabled and magnesium-activated hydrogenation with earth-abundant cobalt catalysts
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Replacing expensive noble metals like Pt, Pd, Ir, Ru, and Rh with inexpensive earth-abundant metals like cobalt (Co) is attracting wider research interest in catalysis. Cobalt catalysts are now undergoing a renaissance in hydrogenation reactions. Herein, we describe a hydrogenation method for polycyclic aromatic hydrocarbons (PAHs) and olefins with a magnesium-activated earth-abundant Co catalyst. When diketimine was used as a ligand, simple and inexpensive metal salts of CoBr2in combination with magnesium showed high catalytic activity in the site-selective hydrogenation of challenging PAHs under mild conditions. Co-catalyzed hydrogenation enabled the reduction of two side aromatics of PAHs. A wide range of PAHs can be hydrogenated in a site-selective manner, which provides a cost-effective, clean, and selective strategy to prepare partially reduced polycyclic hydrocarbon motifs that are otherwise difficult to prepare by common methods. The use of well-defined diketimine-ligated Co complexes as precatalysts for selective hydrogenation of PAHs and olefins is also demonstrated.
- Han, Bo,Jiao, Hongmei,Ma, Haojie,Wang, Jijiang,Zhang, Miaomiao,Zhang, Yuqi
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p. 39934 - 39939
(2021/12/31)
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- Dilithium Amides as a Modular Bis-Anionic Ligand Platform for Iron-Catalyzed Cross-Coupling
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Dilithium amides have been developed as a bespoke and general ligand for iron-catalyzed Kumada-Tamao-Corriu cross-coupling reactions, their design taking inspiration from previous mechanistic and structural studies. They allow for the cross-coupling of alkyl Grignard reagents with sp2-hybridized electrophiles as well as aryl Grignard reagents with sp3-hybridized electrophiles. This represents a rare example of a single iron-catalyzed system effective across diverse coupling reactions without significant modification of the catalytic protocol, as well as remaining operationally simple.
- Neate, Peter G.N.,Zhang, Bufan,Conforti, Jessica,Brennessel, William W.,Neidig, Michael L.
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supporting information
p. 5958 - 5963
(2021/08/18)
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- Nickel-catalyzed reductive deoxygenation of diverse C-O bond-bearing functional groups
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We report a catalytic method for the direct deoxygenation of various C-O bond-containing functional groups. Using a Ni(II) pre-catalyst and silane reducing agent, alcohols, epoxides, and ethers are reduced to the corresponding alkane. Unsaturated species including aldehydes and ketones are also deoxygenated via initial formation of an intermediate silylated alcohol. The reaction is chemoselective for C(sp3)-O bonds, leaving amines, anilines, aryl ethers, alkenes, and nitrogen-containing heterocycles untouched. Applications toward catalytic deuteration, benzyl ether deprotection, and the valorization of biomass-derived feedstocks demonstrate some of the practical aspects of this methodology.
- Cook, Adam,MacLean, Haydn,St. Onge, Piers,Newman, Stephen G.
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p. 13337 - 13347
(2021/11/20)
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- C(sp3)-H Bond Acylation with N -Acyl Imides under Photoredox/ Nickel Dual Catalysis
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A novel Ni/photoredox-catalyzed acylation of aliphatic substrates, including simple alkanes and dialkyl ethers, has been developed. The method combines C-N bond activation of amides with a radical relay mechanism involving hydrogen-atom transfer. The protocol is operationally simple, employs bench-stable N -acyl imides as acyl-transfer reagents, and permits facile access to alkyl ketones under very mild conditions.
- Kerackian, Taline,Reina, Antonio,Krachko, Tetiana,Boddaert, Hugo,Bouyssi, Didier,Monteiro, Nuno,Amgoune, Abderrahmane
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p. 1531 - 1536
(2020/10/21)
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- Three-Component Alkene Difunctionalization by Direct and Selective Activation of Aliphatic C?H Bonds
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Catalytic alkene difunctionalization is a powerful strategy for the rapid assembly of complex molecules and has wide range of applications in synthetic chemistry. Despite significant progress, a compelling challenge that still needs to be solved is the installation of highly functionalized C(sp3)-hybridized centers without requiring pre-activated substrates. We herein report that inexpensive and easy-to-synthesize decatungstate photo-HAT, in combination with nickel catalysis, provides a versatile platform for three-component alkene difunctionalization through direct and selective activation of aliphatic C?H bonds. Compared with previous studies, the significant advantages of this strategy are that the most abundant hydrocarbons are used as feedstocks, and various highly functionalized tertiary, secondary, and primary C(sp3)-hybrid centers can be easily installed. The practicability of this strategy is demonstrated in the selective late-stage functionalization of natural products and the concise synthesis of pharmaceutically relevant molecules including Piragliatin.
- Xu, Sheng,Chen, Herong,Zhou, Zhijun,Kong, Wangqing
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supporting information
p. 7405 - 7411
(2021/02/20)
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- Supported Pt-Ni bimetallic nanoparticles catalyzed hydrodeoxygenation of dibenzofuran with high selectivity to bicyclohexane
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Catalytic hydrodeoxygenation (HDO) is one of the most effective methods to upgrade the oxygen-containing compounds derived from coal tar to valuable hydrocarbons. Herein, an efficient bimetallic catalyst Pt1Ni4/MgO was prepared and applied in the HDO of dibenzofuran (DBF). High yield (95%) of the desired product bicyclohexane (BCH) was achieved at 240 °C and 1.2 MPa of H2. Superior catalytic performance could be ascribed to the “relay catalysis” of Pt sites and Ni sites, and the reaction pathway is proposed as well. Scale-up experiment and recyclability test were also performed, which demonstrated the recyclability and promising potential application of Pt1Ni4/MgO.
- Cai, Chun,Wu, Pengyu
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- Cobalt-catalyzed cross-coupling reactions of aryl- And alkylaluminum derivatives with (hetero)aryl and alkyl bromides
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A simple cobalt complex, such as Co(phen)Cl2, turned out to be a highly efficient and cheap precatalyst for a host of cross-coupling reactions involving aromatic and aliphatic organoaluminum reagents with aryl, heteroaryl and alkyl bromides. New C(sp2)-C(sp2) and C(sp2)-C(sp3) bonds were formed in good to excellent yields and with high chemoselectivity, under mild reaction conditions.
- Dilauro, Giuseppe,Messa, Francesco,Bona, Fabio,Perrone, Serena,Salomone, Antonio
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supporting information
p. 10564 - 10567
(2021/10/19)
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- Palladium and Nickel Catalyzed Suzuki Cross-Coupling with Alkyl Fluorides
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Suzuki cross-coupling of benzylic and unactivated aliphatic fluorides with aryl- and alkenylboronic acids has been achieved via mechanistically distinct Pd and Ni catalyzed pathways that outperform competing protodeboronation, β-hydride elimination, and h
- Balaraman, Kaluvu,Wolf, Christian
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supporting information
p. 8994 - 8999
(2021/11/20)
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- Deep compositional understanding of TBA: AlCl3 ionic liquid for its applications
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Chloroaluminate ionic liquids (ILs) have been immensely used as homogeneous catalyst in Friedel-Crafts reaction. We have recently synthesized chloroaluminate ILs by reacting aluminium chloride with a hydrophobic neutral ligand i.e. tributylamine (TBA:AlCl3). The current study elaborates on the investigations of the composition of the ionic liquids at various stages of their formation. The ionic liquids were synthesized using various mole ratios of tributyl amine and aluminium chloride in range of 1:1 to 1:2.3, in presence of an aromatic solvent in a one pot reaction. Various characterization techniques like Mass spectrometry, 27Al Nuclear Magnetic Resonance, 31P Nuclear Magnetic Resonance and Fourier Transform Infrared spectroscopy were used to elucidate the formation of various moieties of the TBA:AlCl3 Ionic Liquid. This study also elaborates on the investigations of the cationic and anionic moieties and their structure-property relationship for various applications. Various Friedel-Crafts reaction of industrial importance were performed using the ionic liquid having (Al2Cl7)?moiety to assess its performance and compared with conventional processes. The synthesized products were characterised by sophisticated analytical techniques like 1H NMR, 13C NMR, FTIR, GC–MS, GC-FID, to name a few. This class of ionic liquids also have importance in various electrochemical applications like aluminium deposition and aluminium batteries.
- Bhakthavatsalam, Vishnupriya,Chandra, Sudeshna,Choudhury, Rudra Prosad,Lande, Sharad V.,Pradhan, Jeevan,Sakhalkar, Mangesh
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- Highly Active Superbulky Alkaline Earth Metal Amide Catalysts for Hydrogenation of Challenging Alkenes and Aromatic Rings
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Two series of bulky alkaline earth (Ae) metal amide complexes have been prepared: Ae[N(TRIP)2]2 (1-Ae) and Ae[N(TRIP)(DIPP)]2 (2-Ae) (Ae=Mg, Ca, Sr, Ba; TRIP=SiiPr3, DIPP=2,6-diisopropylphenyl). While monomeric 1-Ca was already known, the new complexes have been structurally characterized. Monomers 1-Ae are highly linear while the monomers 2-Ae are slightly bent. The bulkier amide complexes 1-Ae are by far the most active catalysts in alkene hydrogenation with activities increasing from Mg to Ba. Catalyst 1-Ba can reduce internal alkenes like cyclohexene or 3-hexene and highly challenging substrates like 1-Me-cyclohexene or tetraphenylethylene. It is also active in arene hydrogenation reducing anthracene and naphthalene (even when substituted with an alkyl) as well as biphenyl. Benzene could be reduced to cyclohexane but full conversion was not reached. The first step in catalytic hydrogenation is formation of an (amide)AeH species, which can form larger aggregates. Increasing the bulk of the amide ligand decreases aggregate size but it is unclear what the true catalyst(s) is (are). DFT calculations suggest that amide bulk also has a noticeable influence on the thermodynamics for formation of the (amide)AeH species. Complex 1-Ba is currently the most powerful Ae metal hydrogenation catalyst. Due to tremendously increased activities in comparison to those of previously reported catalysts, the substrate scope in hydrogenation catalysis could be extended to challenging multi-substituted unactivated alkenes and even to arenes among which benzene.
- Eyselein, Jonathan,F?rber, Christian,Grams, Samuel,Harder, Sjoerd,Knüpfer, Christian,Langer, Jens,Martin, Johannes,Thum, Katharina,Wiesinger, Michael
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supporting information
p. 9102 - 9112
(2020/03/30)
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- Iterative Preparation of Platinum Nanoparticles in an Amphiphilic Polymer Matrix: Regulation of Catalytic Activity in Hydrogenation
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We demonstrate that iteration of the seeded preparation of platinum nanoparticles dispersed in an amphiphilic polystyrene-poly(ethylene glycol) resin (ARP-Pt) regulates their catalytic activity in the hydrogenation of aromatic compounds in water. The catalytic activity of the fifth generation of ARP-Pt [G5] prepared through four iterations of the seeded preparation was far superior to that of the initial ARP-Pt [G1] in the hydrogenation of aromatic compounds in water.
- Hamasaka, Go,Osako, Takao,Srisa, Jakkrit,Torii, Kaoru,Uozumi, Yasuhiro
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p. 147 - 152
(2020/01/23)
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- Hydroconversion of 2-methylnaphtalene and dibenzothiophene over sulfide catalysts in the presence of water under CO pressure
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Unsupported highly dispersed nanosized catalysts based on transition metal sulfides were prepared insitu, in water-oil emulsions, by high-temperature decomposition of oil soluble metal precursors using elemental sulfur as sulfiding agent. Their catalytic activity was tested in hydroconversion of 2-methylnaphtalene and dibenzothiophene at 380 °C under H2 pressure of 5 MPa. In addition, the catalysts were tested in the same reactions in the CO?H2O medium (p(CO) = 5 MPa, the CO: H2O molar ratio was 2: 1, ω(H2O) = 20 wt.%) in which hydrogen is formed through a water gas shift reaction (WGSR). Unsupported Ni?Mo-sulfide catalysts were found to be the most active compared to catalysts supported on alumina. Transmission electron microscopy served to investigate the structure and determine general geometric characteristics of Ni?Mo?S particles formed in toluene—water medium by decomposition of transition metal naphthenates and hexacarbonyls in the presence of elemental sulfur under CO pressure. The method described in this study enables one to synthesize nanosized catalysts with a high content of active sulfide phase.
- Glotov, A. P.,Karakhanov, E. A.,Maximov, A. L.,Vutolkina, A. V.
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p. 280 - 288
(2020/04/17)
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- Palladium nanoparticles stabilized by novel choline-based ionic liquids in glycerol applied in hydrogenation reactions
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Palladium nanoparticles stabilized by choline-based ionic liquids in glycerol were prepared from Pd(II) precursors by simply heating at 80 °C under argon; in this process, the water present in the ionic liquid was found to be responsible for the reduction of Pd(II) into zero-valent palladium species. Palladium nanoparticles were fully characterized in both liquid phase and solid state. The as-prepared metal nanoparticles exhibited remarkable catalytic activity in hydrogenation processes for a significant variety of functional groups (alkenes, alkynes, nitro derivatives, benzaldehydes, aromatic ketones).
- Garg, Garima,Foltran, Stéphanie,Favier, Isabelle,Pla, Daniel,Medina-González, Yaocihuatl,Gómez, Montserrat
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- Environmentally responsible, safe, and chemoselective catalytic hydrogenation of olefins: ppm level Pd catalysis in recyclable water at room temperature
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Textbook catalytic hydrogenations are typically presented as reactions done in organic solvents and oftentimes under varying pressures of hydrogen using specialized equipment. Catalysts new and old are all used under similar conditions that no longer reflect the times. By definition, such reactions are both environmentally irresponsible and dangerous, especially at industrial scales. We now report on a general method for chemoselective and safe hydrogenation of olefins in water using ppm loadings of palladium from commercially available, inexpensive, and recyclable Pd/C, together with hydrogen gas utilized at 1 atmosphere. A variety of alkenes is amenable to reduction, including terminal, highly substituted internal, and variously conjugated arrays. In most cases, only 500 ppm of heterogeneous Pd/C is sufficient, enabled by micellar catalysis used in recyclable water at room temperature. Comparison with several newly introduced catalysts featuring base metals illustrates the superiority of chemistry in water.
- Gallou, Fabrice,Gao, Eugene S.,Lipshutz, Bruce H.,Takale, Balaram S.,Thakore, Ruchita R.
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supporting information
p. 6055 - 6061
(2020/10/14)
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- Mononuclear calcium complex as effective catalyst for alkenes hydrogenation
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Hydrogenolysis of the scorpionate-supported calcium benzyl complex [(TpAd,iPr)Ca(p-CH2C6H4-Me)(THP)] (TpAd,iPr= hydrotris(3-adamantyl-5-isopropyl-pyrazolyl)borate, THP = tetrahydropyran) (2-THP) afforded the mononuclear calcium hydrido complex [(TpAd,iPr)Ca(H)(THP)] (3). Under mild conditions (40 °C, 10 atm H2, 5 mol% cat.), complex3effectively catalyzed the hydrogenation of a variety of alkenes, including activated alkenes, semi-activated alkenes, non-activated terminal and internal alkenes. Mononuclear calcium unsubstituted alkyl complex [(TpAd,iPr)Ca{(CH2)4Ph}(THP)] (6), proposed as the catalytic hydrogenation intermediate, was isolated and structurally characterized.
- Shi, Xianghui,Hou, Cuiping,Zhao, Lanxiao,Deng, Peng,Cheng, Jianhua
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supporting information
p. 5162 - 5165
(2020/05/26)
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- Method to convert lignin 4-O-5 diaryl ethers and their model compounds into organic chemicals
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It is provided a method of converting a diaryl ether source such as lignin and/or polyphenylene oxide (PPO) containing 4-O-5 linkages and an inorganic chemical such as ammonia into an organic compound, comprising reacting said diaryl ether source with the inorganic chemical in presence of a catalyst, preferably palladium, transforming the 4-O-5 linkages of said diaryl ether source into the organic compound. It is provided a palladium-catalyzed synthesis of aniline derivatives from 4-O-5 linkage lignin model compounds and cheap industrial inorganic chemical ammonia via dual C(Ar)—O bond cleavage.
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Paragraph 11-13
(2020/09/18)
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- General C(sp2)-C(sp3) Cross-Electrophile Coupling Reactions Enabled by Overcharge Protection of Homogeneous Electrocatalysts
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Cross-electrophile coupling (XEC) of alkyl and aryl halides promoted by electrochemistry represents an attractive alternative to conventional methods that require stoichiometric quantities of high-energy reductants. Most importantly, electroreduction can readily exceed the reducing potentials of chemical reductants to activate catalysts with improved reactivities and selectivities over conventional systems. This work details the mechanistically-driven development of an electrochemical methodology for XEC that utilizes redox-active shuttles developed by the energy-storage community to protect reactive coupling catalysts from overreduction. The resulting electrocatalytic system is practical, scalable, and broadly applicable to the reductive coupling of a wide range of aryl, heteroaryl, or vinyl bromides with primary or secondary alkyl bromides. The impact of overcharge protection as a strategy for electrosynthetic methodologies is underscored by the dramatic differences in yields from coupling reactions with added redox shuttles (generally >80%) and those without (generally 20%). In addition to excellent yields for a wide range of substrates, reactions protected from overreduction can be performed at high currents and on multigram scales.
- Hamby, Taylor B.,Sevov, Christo S.,Truesdell, Blaise L.
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p. 5884 - 5893
(2020/04/10)
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- Method for preparing cyclohexylbenzene under catalysis of acidic ionic liquid [PPh3][TfOH]3
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The invention relates to a method for preparing cyclohexylbenzene under catalysis of acidic ionic liquid [PPh3][TfOH]3. The method specifically comprises the following steps: synthesizing the [PPh3][TfOH]3 catalyst from triphenylphosphine and trifluoromethanesulfonic acid according to a molar ratio of 1: 3; by taking the [PPh3][TfOH]3 as a catalyst, slowly dropwise adding a mixed solution of benzene and halogenated cyclohexane at 40-80 DEG C, and reacting the raw materials for 1-3 hours to prepare the cyclohexylbenzene. In the process of preparing cyclohexylbenzene, other organic solvents do not need to be added into a reaction system, and the [PPh3][TfOH]3 serves as the reaction catalyst and a solvent. The [PPh3][TfOH]3 can be repeatedly used, and is green and environment-friendly. The preparation method provided by the invention is simple in process, simple and convenient in post-reaction treatment, green and environment-friendly.
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Paragraph 0028-0055
(2020/01/04)
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- Method for catalytically preparing phenylcyclohexane through acidic ionic liquid [PPh3] [TfOH]2
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The invention relates to a method for catalytically preparing phenylcyclohexane through acidic ionic liquid [PPh3] [TfOH]2. The method specifically comprises the following steps: synthesizing a [PPh3][TfOH]2 catalyst through triphenylphosphine and trifluoromethanesulfonic acid based on the molar ratio of 1:2; slowly dropwise adding a mixed solution of benzene and cyclohexene to the [PPh3] [TfOH]2catalyst under the temperature of 40-80 DEG C; carrying out a reaction for 1-2 to obtain the phenylcyclohexane. According to the method, other organic solvents are not added in the reaction system during preparing the phenylcyclohexane; [PPh3] [TfOH]2 is treated as the reaction catalyst and the solvent; the [PPh3] [TfOH]2 is recyclable, so that the method is environmentally friendly. The preparation method is simple in processes; the treatment after reaction is simple and convenient, green, and environmentally friendly.
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Paragraph 0020-0023; 0024-0027; 0028-0031; 0032-0062
(2019/03/08)
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- Cobalt-Nanoparticles Catalyzed Efficient and Selective Hydrogenation of Aromatic Hydrocarbons
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The development of inexpensive and practical catalysts for arene hydrogenations is key for future valorizations of this general feedstock. Here, we report the development of cobalt nanoparticles supported on silica as selective and general catalysts for such reactions. The specific nanoparticles were prepared by assembling cobalt-pyromellitic acid-piperazine coordination polymer on commercial silica and subsequent pyrolysis. Applying the optimal nanocatalyst, industrial bulk, substituted, and functionalized arenes as well as polycyclic aromatic hydrocarbons are selectively hydrogenated to obtain cyclohexane-based compounds under industrially viable and scalable conditions. The applicability of this hydrogenation methodology is presented for the storage of H2 in liquid organic hydrogen carriers.
- Murugesan, Kathiravan,Senthamarai, Thirusangumurugan,Alshammari, Ahmad S.,Altamimi, Rashid M.,Kreyenschulte, Carsten,Pohl, Marga-Martina,Lund, Henrik,Jagadeesh, Rajenahally V.,Beller, Matthias
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p. 8581 - 8591
(2019/09/12)
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- Breaking the Limit of Lignin Monomer Production via Cleavage of Interunit Carbon–Carbon Linkages
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Conversion of lignin into monocyclic hydrocarbons as commodity chemicals and drop-in fuels is a highly desirable target for biorefineries. However, this is severely hindered by the presence of stable interunit carbon–carbon linkages in native lignin and those formed during lignin extraction. Herein, we report a new multifunctional catalyst, Ru/NbOPO4, that achieves the first example of catalytic cleavage of both interunit C–C and C–O bonds in one-pot lignin conversions to yield 124%–153% of monocyclic hydrocarbons, which is 1.2–1.5 times the yields obtained from the established nitrobenzene oxidation method. This catalyst also exhibits high stability and selectivity (up to 68%) to monocyclic arenes over repeated cycles. The mechanism of the activation and cleavage of 5–5 C–C bonds in biphenyl, as a lignin model adopting the most robust C–C linkages, has been revealed via in situ inelastic neutron scattering coupled with modeling. This study breaks the conventional theoretical limit on lignin monomer production. The conversion of lignin into monocyclic hydrocarbons as commodity chemicals and drop-in fuels is essential for the future of biorefineries. State-of-the-art lignin depolymerization is primarily achieved via cleavage of interunit C–O bonds to form low-molecular-weight feedstocks. However, these processes can hardly cleave interunit C–C bonds in lignin, and thus, the yields of lignin monomers are heavily restricted. Here, we report a multifunctional catalyst, Ru/NbOPO4, that achieves the first example of catalytic cleavage of both interunit C–C and C–O bonds in lignin in one-pot reactions to yield 153% of monocyclic C6–C9 hydrocarbons from Kraft lignin, which is 1.5 times the theoretical yield obtained from the established nitrobenzene oxidation (NBO) method. Thus, significantly, this study successfully breaks the conventional limit on lignin monomer production. Lignin, containing a large volume of aromatic functionalities, is the most energy-dense fraction of renewable biomass. Particularly, conversion of lignin into monocyclic hydrocarbons as commodity chemicals is a highly desirable target. However, this is severally hindered by the presence of stable interunit carbon–carbon linkages in native lignin and those formed during lignin extraction. Here, we report a multifunctional Ru/NbOPO4 catalyst that achieves the first example of catalytic cleavage of both interunit C–C and C–O bonds in lignin in one-pot reactions.
- Dong, Lin,Lin, Longfei,Han, Xue,Si, Xiaoqin,Liu, Xiaohui,Guo, Yong,Lu, Fang,Rudi?, Svemir,Parker, Stewart F.,Yang, Sihai,Wang, Yanqin
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p. 1521 - 1536
(2019/06/14)
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- Benzene Alkylation with Cycloolefins under the Action of [Et3NH]+[Al2Cl7]? Ionic Liquid
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Benzene alkylation with mono- and bicyclic olefins under the action of an inorganic ionic liquid [Et3NH]+[Al2Cl7]? with the formation of benzene cycloalkyl derivatives in 58–98% yield has been performed for the first time. It has been found that the increase in the olefin cycle size improves the selectivity with respect to monocycloalkyl derivatives.
- Aminov,Mazitova,Khusnutdinov
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p. 2171 - 2177
(2020/01/08)
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- Cross-Coupling Reactions of Alkyl Halides with Aryl Grignard Reagents Using a Tetrachloroferrate with an Innocent Countercation
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Bis(triphenylphosphoranylidene)ammonium tetrachloroferrate, (PPN)[FeCl4] (1), was evaluated as a catalyst for cross-coupling reactions. 1 exhibits high stability toward air and moisture and is an effective catalyst for the reaction of secondary alkyl halides with aryl Grignard reagents. The PPN cation is considered as an innocent counterpart to the iron center. We have developed an easy-to-handle iron catalyst for “ligand-free” cross-coupling reactions. (Figure presented.).
- Hashimoto, Toru,Maruyama, Tsubasa,Yamaguchi, Takamichi,Matsubara, Yutaka,Yamaguchi, Yoshitaka
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supporting information
p. 4232 - 4236
(2019/08/16)
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- Synthesis of nickel phosphide nanorods for hydrotreating reactions
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Nickel phosphate (NiPO) nanofibers with high surface area (288 m2/g) were obtained from phosphoric acid and nickel nitrate in an ionic liquid ([Bmim]Br) via an ionothermal synthesis process at 150 °C. Heating the nanofibers under a H2 atmosphere at 700 °C led to the formation of Ni2P nanorods, ~50 nm in diameter and 100–200 nm in length. The Ni2P nanorod catalyst exhibited a much higher turnover frequency in the hydrodesulfurization of dibenzothiophene than the previously reported Ni2P catalysts with nanoparticle, nanosheet or irregular block morphologies, which may be attributable to the morphology effect of the nanorods.
- Zhao, Yu,Wang, Shidong,Li, Ning,Zhang, Qi,Li, Guixian,Shen, Jianyi
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- Sacrificial carbonaceous coating over alumina supported Ni-MoS2 catalyst for hydrodesulfurization
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Recent results have evidenced that carbon plays an important role in stabilizing the structure of the active phase in catalysts. In this work, carbon-coated alumina was prepared by applying polydopamine (PDA) as a sacrificial carbon source to modify the surface properties of γ-alumina, which then was used as a support to prepare supported NiMo catalysts for hydrodesulfurization (HDS) of dibenzothiophene (DBT). NiMo/Al2O3 catalysts exhibited limited hydrodesulfurization performances due to their strong metal-support interaction. Herein, we report an unexpected phenomenon that sacrificial carbon layers can be constructed on the surface of the Al2O3 support from the carbonization of polydopamine (PDA) and mediated the interaction between the active site and support. Through the removal of carbon layers and sulfidation, the resulting NiMo catalysts exhibit excellent performance for HDS reaction of dibenzothiophene (DBT), which is associated with adequate loading of residual carbon species, leading to an enhanced amount of active species under sulfidation conditions. Moreover, the facile synthetic strategy can be extended to the stabilization of the active phase on a broad range of supports, providing a general approach for improving the metal-support interaction supported nanocatalysts.
- Xu, Yingrui,Li, Pengyun,Yuan, Shenghua,Sui, Baokuan,Lai, Weikun,Yi, Xiaodong,Fang, Weiping
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p. 11951 - 11959
(2019/04/30)
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- PROCESS FOR THE PREPARATION OF MOLYBDENUM DISULFIDE NANOPARTICLES SUPPORTED ON TITANIA
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The invention relates to a process for the preparation of nanoparticles of MoS2 supported on TiO2 wherein the preparation is performed by reductive coprecipitation using aqueous solutions containing Ti and Mo precursor salts, and wherein MoS2 may be non-promoted or Co-promoted. Further, the invention relates to the use of said nanoparticles as hydrodesulfurization catalysts.
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Paragraph 0031-0033; 0050
(2019/06/07)
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- Properties of Nanosized Cobalt-Molybdenum Sulfide Catalyst Formed In Situ from Sulfonium Thiosalt
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Abstract: A cobalt-molybdenum-containing sulfonium thiosalt is prepared; when decomposed in situ, it forms the catalyst active in hydrogenation and hydrodesulfurization. The possibility of catalyst isolation and reuse in several hydrogenation cycles is shown. It is found that a lower selectivity for naphthalene hydrogenation products in catalyst recycling is associated with decrease in the dispersity of molybdenum sulfide nanoparticles and reduction in the degree of their promotion by cobalt atoms.
- Knyazeva,Panyukova,Maximov
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p. 504 - 510
(2019/06/19)
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- Highly Active Bulk Mo(W)S2 Hydrotreating Catalysts Synthesized by Etching out of the Carrier from Supported Mono- and Bimetallic Sulfides
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Abstract: A bulk MoWS2 catalyst has been synthesized by acid etching of the carrier from the supported MoWS2/Al2O3 catalyst obtained on the basis of the mixed bimetallic heteropoly acid (HPA) H4[SiMo3W9O40]. As reference samples, monometallic MoS2 and WS2 catalysts have been prepared from the corresponding supported analogues, as well as a Mo + WS2 sample based on a mechanical mixture of monometallic HPA in the atomic ratio of Mo/W = 1/3. The catalytic properties of the synthesized catalysts have been studied in model reactions of hydrodesulfurization (HDS) of dibenzthiophene (DBT) and hydrogenation (HYD) of naphthalene in a flow unit. It has been shown that the catalytic activity of the samples in both the DBT HDS and naphthalene HYD reactions increases in the following order: MoS2 2 2? MoWS2. It has been found that the bulk tungsten-containing catalysts exhibit higher specific catalytic activity than the supported counterparts. Increased values of hydrogen uptake according to the results of hydrogen temperature-programmed reduction for the bulk catalysts indicate an increase in the number of active sites and the formation of a more effective active phase compared to supported catalysts.
- Kokliukhin,Mozhaev,Nikulshina,Lancelot,Blanchard,Lamonier,Nikulshin
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p. S53 - S59
(2020/01/23)
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- Cobalt-Catalyzed Hydrogenations via Olefin Cobaltate and Hydride Intermediates
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Redox noninnocent ligands are a promising tool to moderate electron transfer processes within base-metal catalysts. This report introduces bis(imino)acenaphthene (BIAN) cobaltate complexes as hydrogenation catalysts. Sterically hindered trisubstituted alkenes, imines, and quinolines underwent clean hydrogenation under mild conditions (2-10 bar, 20-80 °C) by use of the stable catalyst precursor [(DippBIAN)CoBr2] and the cocatalyst LiEt3BH. Mechanistic studies support a homogeneous catalysis pathway involving alkene and hydrido cobaltates as active catalyst species. Furthermore, considerable reaction acceleration by alkali cations and Lewis acids was observed. The dinuclear hydridocobaltate anion with bridging hydride ligands was isolated and fully characterized.
- Sandl, Sebastian,Maier, Thomas M.,Van Leest, Nicolaas P.,Kr?ncke, Susanne,Chakraborty, Uttam,Demeshko, Serhiy,Koszinowski, Konrad,De Bruin, Bas,Meyer, Franc,Bodensteiner, Michael,Herrmann, Carmen,Wolf, Robert,Von Jacobi Wangelin, Axel
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p. 7596 - 7606
(2019/08/20)
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- Amine-Borane Dehydrogenation and Transfer Hydrogenation Catalyzed by α-Diimine Cobaltates
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Anionic α-diimine cobalt complexes, such as [K(thf)1.5{(DippBIAN)Co(η4-cod)}] (1; Dipp=2,6-diisopropylphenyl, cod=1,5-cyclooctadiene), catalyze the dehydrogenation of several amine-boranes. Based on the excellent catalytic properties, an especially effective transfer hydrogenation protocol for challenging olefins, imines, and N-heteroarenes was developed. NH3BH3 was used as a dihydrogen surrogate, which transferred up to two equivalents of H2 per NH3BH3. Detailed spectroscopic and mechanistic studies are presented, which document the rate determination by acidic protons in the amine-borane.
- Maier, Thomas M.,Sandl, Sebastian,Shenderovich, Ilya G.,Jacobi von Wangelin, Axel,Weigand, Jan J.,Wolf, Robert
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supporting information
p. 238 - 245
(2019/01/04)
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- Super-Bulky Penta-arylcyclopentadienyl Ligands: Isolation of the Full Range of Half-Sandwich Heavy Alkaline-Earth Metal Hydrides
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Hydrogenolysis of the half-sandwich penta-arylcyclopentadienyl-supported heavy alkaline-earth-metal alkyl complexes (CpAr)Ae[CH(SiMe3)2](S) (CpAr=C5Ar5, Ar=3,5-iPr2-C6H3; S=THF or DABCO) in hexane afforded the calcium, strontium, and barium metal–hydride complexes as the same dimers [(CpAr)Ae(μ-H)(S)]2 (Ae=Ca, S=THF, 2-Ca; Ae=Sr, Ba, S=DABCO, 4-Ae), which were characterized by NMR spectroscopy and single-crystal X-ray analysis. 2-Ca, 4-Sr, and 4-Ba catalyzed alkene hydrogenation under mild conditions (30 °C, 6 atm, 5 mol % cat.), with the activity increasing with the metal size. A variety of activated alkenes including tri- and tetra-substituted olefins, semi-activated alkene (Me3SiCH=CH2), and unactivated terminal alkene (1-hexene) were evaluated.
- Shi, Xianghui,Qin, Guorui,Wang, Yang,Zhao, Lanxiao,Liu, Zhizhou,Cheng, Jianhua
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supporting information
p. 4356 - 4360
(2019/02/25)
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- Magnesium-mediated arylation of amines via C-F bond activation of fluoroarenes
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A series of new Mg(ii) amides featuring a bulky β-diketiminate backstop ligand, has been synthesised. These complexes are demonstrated to be excellent sources of nucleophilic amides that can participate in rapid C-F activation of several fluoroarenes at room temperature or using microwave assistance, leading to the installment of synthetically important C-N bonds via nucleophilic substitution.
- Bole, Leonie J.,Davin, Laia,Kennedy, Alan R.,McLellan, Ross,Hevia, Eva
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supporting information
p. 4339 - 4342
(2019/04/26)
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- Alkene Transfer Hydrogenation with Alkaline-Earth Metal Catalysts
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The alkene transfer hydrogenation (TH) of a variety of alkenes has been achieved with simple AeN′′2 catalysts [Ae=Ca, Sr, Ba; N′′=N(SiMe3)2] using 1,4-cyclohexadiene (1,4-CHD) as a H source. Reaction of 1,4-CHD with AeN′′2 gave benzene, N′′H, and the metal hydride species N′′AeH (or aggregates thereof), which is a catalyst for alkene hydrogenation. BaN′′2 is by far the most active catalyst. Hydrogenation of activated C=C bonds (e.g. styrene) proceeded at room temperature without polymer formation. Unactivated (isolated) C=C bonds (e.g. 1-hexene) needed a higher temperature (120 °C) but proceeded without double-bond isomerization. The ligands fully control the course of the catalytic reaction, which can be: 1) alkene TH, 2) 1,4-CHD dehydrogenation, or 3) alkene polymerization. DFT calculations support formation of a metal hydride species by deprotonation of 1,4-CHD followed by H transfer. Convenient access to larger quantities of BaN′′2, its high activity and selectivity, and the many advantages of TH make this a simple but attractive procedure for alkene hydrogenation.
- Bauer, Heiko,Thum, Katharina,Alonso, Mercedes,Fischer, Christian,Harder, Sjoerd
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supporting information
p. 4248 - 4253
(2019/03/07)
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- Nickel-catalyzed C-N bond activation: Activated primary amines as alkylating reagents in reductive cross-coupling
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Nickel-catalyzed reductive cross coupling of activated primary amines with aryl halides under mild reaction conditions has been achieved for the first time. Due to the avoidance of stoichiometric organometallic reagents and external bases, the scope regarding both coupling partners is broad. Thus, a wide range of substrates, natural products and drugs with diverse functional groups are tolerated. Moreover, experimental mechanistic investigations and density functional theory (DFT) calculations in combination with wavefunction analysis have been performed to understand the catalytic cycle in more detail.
- Yue, Huifeng,Zhu, Chen,Shen, Li,Geng, Qiuyang,Hock, Katharina J.,Yuan, Tingting,Cavallo, Luigi,Rueping, Magnus
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p. 4430 - 4435
(2019/04/29)
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- Visible-Light-Promoted Iron-Catalyzed C(sp2)–C(sp3) Kumada Cross-Coupling in Flow
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A continuous-flow, visible-light-promoted method has been developed to overcome the limitations of iron-catalyzed Kumada–Corriu cross-coupling reactions. A variety of strongly electron rich aryl chlorides, previously hardly reactive, could be efficiently coupled with aliphatic Grignard reagents at room temperature in high yields and within a few minutes’ residence time, considerably enhancing the applicability of this iron-catalyzed reaction. The robustness of this protocol was demonstrated on a multigram scale, thus providing the potential for future pharmaceutical application.
- Wei, Xiao-Jing,Abdiaj, Irini,Sambiagio, Carlo,Li, Chenfei,Zysman-Colman, Eli,Alcázar, Jesús,No?l, Timothy
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supporting information
p. 13030 - 13034
(2019/07/18)
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- An Effect of a Support Nature and Active Phase Morphology on Catalytic Properties of Ni-Containing Catalysts in Hydrogenation of Biphenyl
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Ni/Sup catalysts were prepared, where SBA-15, γ-Al2O3, SiO2 were used as supports (Sup). The synthesized catalysts were investigated by the methods of low-temperature nitrogen adsorption, temperatureprogrammed reduction (TPR), and high-resolution transmission electron microscopy. The catalytic properties of the prepared catalysts were tested in liquid phase hydrogenation of biphenyl under conditions of a flow installation at temperatures of 60–100°C, pressure of 4 MPa, volumetric feed rate of 4–10 h–1 and H2: feed ratio of 1500 nM. A 1 wt % solution of biphenyl in heptane, as a model mixture, was used. It has been established that the activity of nickel hydrogenation catalysts depends on the nickel content and the type of support. The activity of supported nickel catalysts decreases in the series Ni-12/SBA-15 > Ni-12/SiO2 >> Ni-12/Al2O3. The kinetic characteristics of the biphenyl hydrogenation reaction were determined: the rate constants and activation energy for the hydrogenation of the first and second aromatic rings of the substrate molecule.
- Chernova,Minayev,Martynenko, Ye. A.,Pimerzin, Al. A.,Yeremina, Yu. V.,Verevkin,Pimerzin
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p. 1701 - 1710
(2019/01/14)
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- Ruthenium nanoparticles ligated by cholesterol-derived NHCs and their application in the hydrogenation of arenes
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Herein we present ruthenium nanoparticles (Ru-NPs) stabilized with two rigid NHC ligands derived from cholesterol. The obtained nanoparticles were fully characterized and applied in the hydrogenation of various aromatic compounds under mild conditions. Interestingly, the more bulky ligand gives a slightly lower ligand coverage and a faster catalyst.
- Rakers, Lena,Martínez-Prieto, Luis M.,López-Vinasco, Angela M.,Philippot, Karine,Van Leeuwen, Piet W. N. M.,Chaudret, Bruno,Glorius, Frank
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p. 7070 - 7073
(2018/07/05)
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