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排序方式: 共有204条查询结果,搜索用时 203 毫秒
1.
J. Llorca A. Barbier G. A. Martin J. Sales P. Ramírez de la Piscina N. Homs 《Catalysis Letters》1996,42(1-2):87-91
Hydroformylation of ethylene and CO hydrogenation were studied over cobalt-based catalysts derived from reaction of Co2(CO)8 with ZnO, MgO and La2O3 supports. At 433 K a similar activity sequence was reached for both reactions: Co/ ZnO > Co/La2O3 > Co/MgO. This confirms the deep analogy between hydroformylation and CO hydrogenation into alcohols. In the CO hydrogenation the selectivity towards alcohol mixture (C1-C3) was found to be near 100% at 433 K for a conversion of 6% over the Co/ZnO catalyst; this catalyst showed oxo selectivity higher than 98% in the hydroformylation of ethylene. Magnetic experiments showed that no metallic cobalt particles were formed at 433 K. It is suggested that the active site for the step that is common to both reactions is related to the surface homonuclear Co2+/[Co(CO)4]– ion-pairing species. 相似文献
2.
Pramod Kandanarachchi Andrew Guo Dmytro Demydov Zoran Petrovic 《Journal of the American Oil Chemists' Society》2002,79(12):1221-1225
The kinetics and mechanism of the hydroformylation of soybean oil by homogeneous ligand-modified rhodium catalysts were investigated
at 70–130°C and 4000–11,000 kPa. The effects of reaction rates on systematic variations in reaction parameters were evaluated
in order to develop an industrial process to convert vegetable oils to polyaldehydes. The activation energies in the presence
of triphenylphosphine (Ph3P) (61.1±0.8 kJ/mol) (mean±SD) and triphenyl phosphite [(PhO)3P] (77.4±5.0 kJ/mol) were determined. The catalyst was deactivated at temperatures higher than 100°C. An evaluation of the
effects of the reaction parameters on initial rates yielded the rate laws for Ph3P {rate=k [olefin][Rh(CO)2Acac]1.1 [Ph3P]−0.5 (pH2+pCO)1.4, where Rh(CO)2Acac is (acetylacetonato)dicarbonylrhodium (I)} and (PhO)3P {rate=[olefin] [Rh(CO)2Acac]1.2 [(PhO)3P]−0.8 (pH2+pCO)0.9 at total pressures lower than 7000 kPa, and rate =[olefin] [Rh(CO)2Acac]1.2 [(PhO)3P]−0.8(pH2+pCO)1.7 at total pressures higher than 7000 kPa}. 相似文献
3.
4.
Kazuhiko Takeuchi Taka-aki Hanaoka Takehiko Matsuzaki Matti Reinikainen Yoshihiro Sugi 《Catalysis Letters》1991,8(2-4):253-261
Vapor phase hydroformylation of ethylene was studied with silica-supported metal catalysts. A cobalt metal catalyst derived from Co2(CO)8 gave propanal and its derivatives in as high selectivity of about 36% as Rh/SiO2 catalyst under the reaction conditions of 1.1 MPa of a gas-mixture of ArCOC2H4H2 = 1333 at 423–503 K. On the other hand, conventional cobalt catalysts derived from cobalt nitrate, chloride, or acetate, and other noble metal catalysts (Pd/SiO2 and Ir/SiO2) produced mainly ethane. 相似文献
5.
The catalytic activity and selectivity of heterodonor phosphine rhodium catalysts prepared in situ were tested in the hydroformylation of functional alkenes (ethyl acrylate, methyl methacrylate, styrene, 4-vinyl-1-cyclohexene, dicyclopentadiene and cis-1,2,3,6-tetrahydrophthalic anhydride). Systematic variation of the heterodonor atom in the ortho position of the ligand showed that the heterodonor atom has a significant influence on the activities and selectivities of the reaction. However, the activity seems to depend mainly on the modifying ligand, and the regioselectivity mainly on the substrate (i.e., the structure and functionality of the alkene). Nevertheless, regioselective control is only obtained through synergy between the substrate and the catalyst. Clear regiocontrol was observed in the hydroformylation of ,-unsaturated esters and styrene with an in situ formed o-(thiomethylphenyl)diphenylphosphine rhodium catalyst. 相似文献
6.
采用水热合成法制备Si-MCM-41介孔分子筛,并在其上担载HRh(CO)(PPh3)3络合物合成负载型催化剂,考察了该载体Si-MCM-41分子筛的制备条件对异丁烯氢甲酰化反应的影响。实验结果表明分子筛的制备条件中pH值,原料配比,晶化温度对反应性能的影响最显著,在pH=10,n(Si)∶n(CTAB)=1∶0.2和晶化温度为120℃的条件下制备的Si-MCM-41载体对异丁烯氢甲酰化制异戊醛的选择性达最优。采用低温液氮吸附脱附分析(BET)和X射线衍射分析(XRD)技术对载体Si-MCM-41和负载型HRh(CO)(PPh3)3-MCM-41催化剂进行表征,结果表明载体在负载络合物后仍然保持了较好的介孔特征,其较均匀的孔径分布表现出对反应产物较好的择形催化性能。 相似文献
7.
P. Ramírez de la Piscina J. L. G. Fierro G. Muller J. Sales N. Homs 《Catalysis Letters》1992,14(1):45-49
New heterogenized Pt/Sn catalysts selective for the hydroformylation of 1-pentene have been synthesized. The complex cis-[PtCl2(PPh3)2] and the SnCl2.2H2O or SnC2O4 precursors have been anchored on silica-, magnesia- and alumina-carriers. X-ray photoelectron spectroscopy was used to determine the surface composition and the nature of the anchored species. The hydroformylation activity was found to depend on the type of support and tin precursor used. Only the silica supported catalysts were active in the hydroformylation reaction. Samples prepared from SnCl2-2H2O were 200-fold more active than those prepared from SnC2O4. Selectivity ton-hexanal of the silica-supported catalyst prepared from SnCl2-2H2O was as high as 94.4% at 39.2% conversion of 1-pentene. 相似文献
8.
9.
铑催化剂的使用量直接影响到羰基合成工艺的经济效益。本研究使用g PROMS软件对丙烯羰基化过程进行了过程模拟,在工况数据的基础上修正了反应动力学及催化剂的失活动力学参数,并做了催化剂失活情况下为期4年的长周期的动态过程建模。本模型根据当前工况在生产全周期中所处的位置、铑催化剂的价格以及催化剂的使用情况,对生产周期后续时间段进行了催化剂的增加策略优化、温度优化、出口气体CO浓度优化,全周期内整体的生产利润提高了2%。本研究对羰基合成工艺实际生产具有一定的指导意义,并为涉及到催化剂失活的其他工艺提供了参考。 相似文献
10.
The hydroformylation of olefins with the water soluble complex HRh(CO) [P(m-C6H4SO3Na)3]3 (1) is dependent on the solubility of the olefins in the aqueous phase. In contrast, when the aqueous solution of1 is immobilized on a high surface area silica support the effects of the size of the olefins diminish. The immobilized catalyst1 on silica shows significant water loss but not rhodium leaching. It is proposed that the hydrophilic support holds the water soluble phosphines by hydrogen bonding of the hydrated sodium-sulphonate groups to the surface. 相似文献