629-11-8Relevant academic research and scientific papers
Determining Roles of Cu0 in the Chemosynthesis of Diols via Condensed Diester Hydrogenation on Cu/SiO2 Catalyst
Wang, Weichao,Wang, Hui,Zhang, Jingwei,Kong, Lingxin,Huang, Huijiang,Liu, Wei,Wang, Shengping,Ma, Xinbin,Zhao, Yujun
, p. 3849 - 3852 (2020)
Copper-based catalyst was applied in the condensed diester hydrogenation with unexpected high selectivity (～100 percent) to 1,6-hexanediol. On basis of the mass transfer analysis and kinetics results, the reaction rate of the condensed diester hydrogenation was deduced to be controlled by the activation of hydrogen on Cu0 sites, which was further demonstrated by the correlations between the catalytic activity and different copper species. Importantly, this catalysis mechanism is different with that of gas-phase diester hydrogenation, which is generally determined by the adsorption of ester on Cu+ species.
CuZn Catalysts Superior to Adkins Catalysts for Dimethyl Adipate Hydrogenolysis
Pospelova, Violetta,Aubrecht, Jaroslav,Kikhtyanin, Oleg,Pacultová, Kate?ina,Kubi?ka, David
, p. 2169 - 2178 (2019)
Industrial hydrogenolysis of esters to alcohols relies on the use of Adkins catalysts whose production and disposal is an environmental burden. This work is focused on CuZn catalysts that represent an ecological alternative to Adkins catalysts. Four CuZn catalysts with Cu/Zn atomic ratio ranging from 0.5 to 2.0 and single phase CuO and ZnO catalysts were prepared by co-precipitation and their hydrogenolysis activity was compared with a commercial Adkins catalyst. Dimethyl adipate was used to test the catalyst performance in a flow reactor at temperatures ranging from 175 to 205 °C and hydrogen pressure of 16 MPa. The increase in ZnO content was directly responsible for the reduction in copper crystallite size and increase in the catalyst specific surface area. The CuZn catalysts exhibited higher conversion than the Adkins catalyst despite their specific surface area declined during the experiments more significantly than that of the Adkins catalyst. Nonetheless, the TOF of CuZn catalysts exceeded that of the commercial Adkins catalyst.
On the selective acid-catalysed dehydration of 1,2,6-hexanetriol
Nolan, Michael R.,Sun, Geng,Shanks, Brent H.
, p. 2260 - 2266 (2014)
Selectivity results for the dehydration of 1,2,6-hexanetriol over solid acid catalysts are reported. A slate of catalysts including zeolites, amorphous silica-alumina, and niobias were tested and the selectivity towards either cyclic ethers or α,ω-dioxygenates was found to be mildly correlated with the acid strength of the fresh catalyst. In general, a ring closing dehydration reaction to a pyran was the dominant reaction pathway. Differences in the catalysts were mitigated by significant coke formation.
Synthesis of Supported RhMo and PtMo Bimetallic Catalysts by Controlled Surface Reactions
Alba-Rubio, Ana C.,Sener, Canan,Hakim, Sikander H.,Gostanian, Thomas M.,Dumesic, James A.
, p. 3881 - 3886 (2015)
We previously described a synthesis method to prepare bimetallic catalysts with narrow nanoparticle size and composition distributions by means of controlled surface reactions (CSR) between a reduced supported metal nanoparticle and an organometallic precursor of an oxophilic promoter metal. Herein, we report a comparison of such catalysts with those prepared by traditional incipient wetness impregnation. STEM/EDS analysis indicates that catalysts prepared by CSR exhibit more effective interaction of metals, thereby minimizing the undesirable formation of component-rich nanoparticles and/or monometallic domains. Reaction kinetics studies using these bimetallic catalysts reveal that optimal conversion rates in a selective CO hydrogenolysis reaction (i.e., hydrogenolysis of 2-(hydroxymethyl)tetrahydropyran to 1,6-hexanediol) could be achieved using a lower amount of the oxophilic promoter metal for the catalysts prepared by the CSR approach, as compared to their impregnated counterparts. A superior method for greater results: At the same conversion rate level, catalysts prepared by controlled surface reactions (CSR) requires smaller amount of promoter as compared to those prepared by incipient wetness impregnation (IWI). This increased performance is attributed to the uniform bimetallic composition of the catalysts prepared by CSR.
Ti3+ Tuning the Ratio of Cu+/Cu0 in the Ultrafine Cu Nanoparticles for Boosting the Hydrogenation Reaction
Zhang, Ziyang,Wang, Zhong-Li,An, Kang,Wang, Jiaming,Zhang, Siran,Song, Pengfei,Bando, Yoshio,Yamauchi, Yusuke,Liu, Yuan
, (2021)
Hydrogenation of diesters to diols is a vital process for chemical industry. The inexpensive Cu+/Cu0-based catalysts are highly active for the hydrogenation of esters, however, how to efficiently tune the ratio of Cu+/Cu0 and stabilize the Cu+ is a great challenge. In this work, it is demonstrated that doped Ti ions can tune the ratio of Cu+/Cu0 and stabilize the Cu+ by the Ti-O-Cu bonds in Ti-doped SiO2 supported Cu nanoparticle (Cu/Ti–SiO2) catalysts for the high conversion of dimethyl adipate to 1,6-hexanediol. In the synthesis of the catalysts, the Ti4+-O-Cu2+ bonds promote the reduction of Cu2+ to Cu+ by forming Ti3+-OV-Cu+ (OV: oxygen vacancy) bonds and the amount of Ti doping can tune the ratio of Cu+/Cu0. In the catalytic reaction, the O vacancy activates C=O in the ester by forming new Ti3+δ-OR-Cu1+δ bonds (OR: reactant oxygen), and Cu0 activates hydrogen. After the products are desorbed, the Ti3+δ-OR-Cu1+δ bonds return to the initial state of Ti3+-OV-Cu+ bonds. The reversible Ti-O-Cu bonds greatly improve the activity and stability of the Cu/Ti–SiO2 catalysts. When the content of Ti is controlled at 0.4?wt%, the conversion and selectivity can reach 100% and 98.8%, respectively, and remain stable for 260 h without performance degradation.
Reductive depolymerization of polyesters and polycarbonates with hydroboranes by using a lanthanum(iii) tris(amide) catalyst
Berthet, Jean-Claude,Cantat, Thibault,Kobylarski, Marie
supporting information, p. 2830 - 2833 (2022/03/09)
The homogeneous reductive depolymerization of polyesters and polycarbonates with hydroboranes is achieved with the use of an f-metal complex catalyst. These polymeric materials are transformed into their value-added alcohol equivalents. Catalysis proceeds readily, under mild conditions, with La[N(SiMe3)2]3 (1 mol%) and pinacolborane (HBpin) and shows high selectivity towards alcohols and diols, after hydrolysis.
Towards efficient Cu/ZnO catalysts for ester hydrogenolysis: The role of synthesis method
Aubrecht, Jaroslav,Kikhtyanin, Oleg,Kubi?ka, David,Pospelova, Violetta
, (2021/08/21)
Cu/ZnO catalysts represent an environmentally friendly alternative to Adkins catalysts used for ester hydrogenolysis. Cu/ZnO are mostly synthesized by co-precipitation (COP); however, other synthesis methods may help to obtain small highly dispersed Cu crystallites advantageous for catalyst activity. A comparative study on the effect of synthesis method on Cu/ZnO catalysts properties and activity is missing. Thus, we synthesized 8 wt% Cu/ZnO catalysts by five methods (COP, deposition-precipitation (DP), chemisorption-hydrolysis (CH), incipient wetness (IWI) and wet impregnation (WI)), characterized and tested them in dimethyl adipate hydrogenolysis. The CH-prepared catalyst was prone to Cu sintering, which impaired its performance. IWI led to large Cu nanoparticles, pore blocking and poor catalytic performance. COP and DP resulted in the smallest Cu nanoparticles (13?14 nm), largest Cu surface area (3.9–4.2 m2 gcat?1) and specific surface area (40?43 m2 gcat?1) reflected in their superior catalytic activity making DP a good alternative to COP to prepare active Cu/ZnO catalysts.
Method for preparing 1, 6-hexamethylenediamine from 5-hydroxymethylfurfural
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Paragraph 0140; 0146-0147, (2021/06/06)
The invention relates to a method for preparing 1, 6-hexamethylenediamine from 5-hydroxymethylfurfural, which is characterized in that the 5-hydroxymethylfurfural is used as a raw material, and the 1, 6-hexamethylenediamine is synthesized by a two-step method under the action of a catalyst. The method comprises the following steps: 1) in a hydrogen atmosphere, reacting the raw material 5-hydroxymethylfurfural with ammonia in the presence of a reductive amination catalyst to generate 2, 5-dimethylamine tetrahydrofuran; and 2) continuing the reaction, and carrying out a ring-opening reaction on the hydrodeoxygenation catalyst to produce the target product 1, 6-hexamethylenediamine. The method is characterized in that the reductive amination catalyst in the step 1) is an M1-M2 supported multi-metal component catalyst. The method is characterized in that the hydrodeoxygenation catalyst in the step 2) is a supported catalyst, and the metal active component is selected from one or more of transition metal elements Rh, Re, Pt, Ir, Pd and Ru. The 1, 6-hexamethylenediamine is produced by using the bio-based material monomer 5-hydroxymethylfurfural as the raw material, so that the method is green and clean, the process is easy to operate, the yield is high, and a wide application prospect is provided for biomass conversion.
Method for preparing 1, 5-pentanediol or 1, 6-hexanediol from bio-based furan compound
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Paragraph 0006; 0020, (2021/06/26)
The invention discloses a method for preparing 1, 5-pentanediol or 1, 6-hexanediol by utilizing a bio-based furan compound, which comprises the following steps of: reacting the bio-based furan compound serving as a raw material for 1-48 hours in a proper solvent under the conditions of pressure of 0.5-10 MPa and temperature of 20-200 DEG C in a reducing gas atmosphere under the action of a catalyst, separating the catalyst, and distilling out the solvent to obtain the target product 1,5-pentanediol or 1, 6-hexanediol. According to the method disclosed by the invention, efficient conversion of the bio-based furan compound is realized under relatively mild and environment-friendly conditions by utilizing chemically synthesized renewable resource bio-based furan, and the produced 1, 5-pentanediol or 1, 6-hexanediol is a polymer monomer, so that the application range of the bio-based furan compound is expanded, the comprehensive utilization of the straws is further promoted, and carbon neutralization is promoted.
Understanding of the key properties of supported Cu-based catalysts and their influence on ester hydrogenolysis
Aubrecht, Jaroslav,Kikhtyanin, Oleg,Kubi?ka, David,Lhotka, Miloslav,Pospelova, Violetta
, (2021/10/19)
The application of Cr-free Cu-based catalysts in ester hydrogenolysis is a modern environmentally-friendly research approach. The comprehensive study of four supported Cu-based catalysts was performed using 8 wt% of Cu loaded on Al2O3, ZnO, TiO2 and ZrO2 supports by an impregnation method. Using XRD, H2-TPR, BET, pyridine-TPD, CO2-TPD and N2O-RFC methods, the effect of the support on the formation of Cu-nanoparticles was described. Al2O3 was evaluated as the support ensuring the highest nanoparticles dispersion, while Cu nanoparticles in Cu-TiO2 were liable to sintering. The catalysts were tested in dimethyl adipate hydrogenolysis, where the catalyst performance and activity (TOF) were evaluated and Cu-ZrO2 showed the best results. A correlation between the number of acid-base sites and the catalyst selectivity was revealed and the catalyst effect on the formation of various by-products was described. The intrinsic selectivity to hydrogenolysis products was found to decrease with the increasing acid-base character of the supports whereas the selectivity to transesterification and cyclization products increased. The hydrogenolysis activity was not a simple function of the number of the surface copper atoms, but it was affected by the support nature and its properties.
