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141.
Montes M. Getton F.P. Vong M.S.W. Sermon P.A. 《Journal of Sol-Gel Science and Technology》1997,8(1-3):131-137
Titania on silica samples have been prepared by: i) precipitation-deposition from a solution of TiCl3 onto the surface of a commercial silica, and ii) base catalysed hydrolysis-condensation of TEOS followed by reaction with
Ti isopropoxide. These samples were characterised by nitrogen and hydrogen adsorption, X-ray diffraction, FTIR, temperature
programmed reduction, transmission electron microscopy and catalytic activity in butane-hydrogen conversion. The sol-gel preparation
produced a better titania dispersion due to the formation of stabilising Ti-O-Si bonds. Upon these samples was then introduced
Ir. Strong metal-support interactions between Ir and titania have been observed after high temperature reduction, causing
a significantincrease in butane dehydrogenation activity relative to hydrogenolysis.It appears that using sol-gel chemistry useful supports for catalytic metals containing Si-O-Ti linkages can be produced and
in future may be optimised for other metal-oxygen metal pairs. 相似文献
142.
The catalytic conversion of benzyl alcohol to toluene and benzaldehyde was performed on YBa2Cu3O7–x (Y–Ba–Cu–O) in the presence of hydrogen at 250–400°C. The catalytic characteristics of Y–Ba–Cu–O were compared with those of CuO, Cu/SiO2 and Y2BaCuO5. The structural changes in the catalysts during the reaction were measured by means of XRD and SEM. It was found that the oxidation state of the copper in Y–Ba–Cu–O was a considerable factor in the conversion of benzyl alcohol.Part I:React. Kinet. Catal. Lett.
51, 61 (1993). 相似文献
143.
Alkylation of lactam 10, first with iodide 15 and then with MeI, gave mainly (18:1) lactam 18. This was converted by treatment with t-BuLi and then with aqueous base into enone 4, which was elaborated into (−)-hamigeran B. A key feature of the last part of the synthesis is the use of t-BuMe2Si-groups (as in intermediate 24) both to direct hydrogenation from the appropriate face and to protect the benzylic CO bond from hydrogenolysis. 相似文献
144.
Nobuhiro Iwasa Masao Terashita Masahiko Arai Nobutsune Takezawa 《Reaction Kinetics and Catalysis Letters》2001,74(1):93-98
The catalytic performance of supported Pd and Pt catalysts for the title reaction was greatly improved upon the formation
of Pd and Pt alloys. Over Pd and Pt alloys, methyl formate was selectively hydrogenolyzed to methanol, while over metallic
Pd and Pt, it was decarbonylated to methanol and carbon monoxide.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
145.
竹浆纤维素转化制低碳多元醇反应中有机氮对金属催化剂稳定性影响的研究 《燃料化学学报》2019,47(6):675-687
采用等体积浸渍法制备了一系列多孔竹炭负载的有机氮掺杂的镍钨催化剂,并将其应用于催化竹浆纤维氢解制C2,3多元醇反应。有机氮源与催化剂前驱体中Ni2+络合,高温煅烧时载体表面碳、氮和金属离子相互作用后生成一定量的C3N4、氮化物和合金物相。通过XRD、XPS和TEM等表征手段分析了催化剂Ni-W/MBC表面物理化学性质与催化活性间的关系。结果表明,除了金属镍、氧化钨物相外,表面还含有Ni-W合金(NiWO4为主);金属粒子表面包围了一层石墨化C3N4物相。XPS分析表明,有机氮源高温分解反应后形成了C3N4物相。在反应条件下,15% Ni-20% W/MBC@M-0.25催化剂得到乙二醇收率为55.8%,而未添加有机氮源的催化剂15% Ni-20% W/MBC获得的乙二醇收率仅为36.9%。催化剂稳定性实验结果表明,Ni-W合金和C3N4物相的形成显著增强了Ni-W/MB催化剂的稳定性,延长了催化剂寿命。 相似文献
146.
Xiao-feng Cao Qi Zhang Dong Jiang Qi-ying Liu Long-long Ma Tie-jun Wang De-bao Li 《化学物理学报(中文版)》2015,28(3):338-344
A series of Ni based catalysts with different supports and basic additives were prepared by sequential impregnation method. The catalysts were characterized by XRD, BET, H2-TPR and CO2-TPD techniques. It was found that the introduction of basic additives enhanced the basicities of catalyats and promoted the dispersities of Ni particles by strong interaction between Ni2+ and basic additives. Among the Ni based catalysts, 10%Ni/10%La2O3/ZrO2 showed the superior performance in sorbitol hydrogenolysis. The synergistic effect of Ni and La2O3 was proven to play an essential role in selective synthesis of EG and 1,2-PG. In the optimal reaction condition, the catalyst presented 100% sorbitol conversion and over 48% glycols (EG and 1,2-PG) yield. The kinetics study of polyols (sorbitol, xylitol and glycerol) hydrogenolysis showed that polyols with more hydroxyl number have higher activity and products distribution was final results of kinetic balance, which could give us some inspiration about how to change the products selectivity. 相似文献
147.
148.
Asymmetric Total Synthesis of Propindilactone G,Part 2: Enantioselective Construction of the Fully Functionalized BCDE Ring System
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Jia‐Jun Zhang Dr. Lin You Dr. Yue‐Fan Wang Yuan‐He Li Xin‐Ting Liang Bo Zhang Dr. Shou‐Liang Yang Qi Su Prof. Dr. Jia‐Hua Chen Prof. Dr. Zhen Yang 《化学:亚洲杂志》2016,11(9):1414-1424
The enantioselective synthesis of the fully functionalized BCDE tetracyclic ring system of propindilactone G ( A ) is reported. Several synthetic methods were developed and applied to achieve this goal, including: 1) an asymmetric Diels–Alder reaction in the presence of Hayashi′s catalyst for the synthesis of optically pure key intermediate 3 ; 2) an intramolecular Pauson–Khand reaction (PKR) for the stereoselective synthesis of the BCDE ring with an all‐carbon chiral quaternary center at the C13 position by using the TMS‐substituted acetylene as the substrate; and 3) Pd‐catalyzed reductive hydrogenolysis for the stereoselective synthesis of the fully functionalized BCDE tetracyclic ring system. The chemistry developed herein provided a greater understanding of the total synthesis propindilactone G ( A ) and its analogues. 相似文献
149.
Runhai Chen Guorui Qin Shihui Li Alison J. Edwards Ross O. Piltz Iker Del Rosal Laurent Maron Dongmei Cui Jianhua Cheng 《Angewandte Chemie (International ed. in English)》2020,59(28):11250-11255
Hydrogenolysis of alkyl‐substituted cyclopentadienyl (CpR) ligated thorium tribenzyl complexes [(CpR)Th(p‐CH2‐C6H4‐Me)3] ( 1 – 6 ) afforded the first examples of molecular thorium trihydrido complexes [(CpR)Th(μ‐H)3]n (CpR=C5H2(tBu)3 or C5H2(SiMe3)3, n=5; C5Me4SiMe3, n=6; C5Me5, n=7; C5Me4H, n=8; 7 – 10 and 12 ) and [(Cp#)12Th13H40] (Cp#=C5H4SiMe3; 13 ). The nuclearity of the metal hydride clusters depends on the steric profile of the cyclopentadienyl ligands. The hydrogenolysis intermediate, tetra‐nuclear octahydrido thorium dibenzylidene complex [(Cpttt)Th(μ‐H)2]4(μ‐p‐CH‐C6H4‐Me)2 (Cpttt=C5H2(tBu)3) ( 11 ) was also isolated. All of the complexes were characterized by NMR spectroscopy and single‐crystal X‐ray analysis. Hydride positions in [(CpMe4)Th(μ‐H)3]8 (CpMe4=C5Me4H) were further precisely confirmed by single‐crystal neutron diffraction. DFT calculations strengthen the experimental assignment of the hydride positions in the complexes 7 to 12 . 相似文献
150.