共查询到20条相似文献,搜索用时 156 毫秒
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本文合成了联接有硫醚基的二氧化硅固载的金属钯催化剂.结果表明:(1)该催化剂在常温常压下对环戊二烯具有较高的催化氢化活性,并能选择性地生成环戊烯.在环戊二烯转化100%时,生成环戊烯的选择性达97.7%.(2)该催化剂有良好的稳定性,可多次重复使用,保持高活性和选择性不变.经透射电镜观察,远红外分析以及X—光光电子能谱分析测定,催化剂的活性中心是颗粒大小为10—60(?)的钯金属微粒. 相似文献
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部分中毒Pd/C催化剂上环戊二烯的加氢反应 总被引:3,自引:0,他引:3
用固定床反应器考察了Pd/C催化剂硫化前后环戊二烯的加氢性能,Pd/C催化剂经硫化后,生成环戊烯的得率由75%上升到97%。确定了最佳硫化条件。应用微型脉冲反应器和程序升温表面反应(TPSR)研究了硫化特性,发现硫在Pd/C催化剂在存在着两种吸附状态,吸附在对应于TPSR中低温峰位上的硫不影响加氢反应活性,吸附在对应于高温峰位上的硫引起催化剂催化活性下降。 相似文献
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非晶态金属合金作催化材料的研究I:N-P非晶态合金对苯乙烯加氢活性的研究 总被引:10,自引:0,他引:10
本文用X射线光电子能谱(XPS), X射线衍射(XRD)和连续微型反应器等方法研究了以骤冷法制备的Ni-P非晶态催化剂的表面结构和加氢活性。结果表明, 非晶态Ni-P对于苯乙烯催化加氢具有很高的反应活性, 优于晶态Ni-P, 更优于Ni片, 催化剂表面不同的预处理条件, 对反应活性影响很大。XPS结果表明, 在适当的预处理条件下, 非晶态Ni-P被部分氧化;随着氧化态被还原, 反应活性逐渐下降。 相似文献
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Substituted alkylmethylenecyclohexanes were hydrogenated over several transition metal catalysts. The ratios of the epimeric products were almost unity over freshly prepared Raney Ni but the axial Me counterparts were favoured over aged catalyst. The axial Me products were also preferred on Pt or Rh catalysts. Pd catalysed hydrogenation gave predominantly the equatorial Me isomers at high catalyst ratio, while the axial Me counterparts were favoured at the early stage of the reaction at a catalyst-substrate ratio of 1:20. The change of the ratio of epimeric products depending on the amount of catalyst is due to the rapid migration of exo-cyclic double bond to the inside of the cyclohexane ring at high catalyst ratio. The mechanism of hydrogenation is discussed in terms of the modified Horiuti-Polanyi mechanism. 相似文献
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A novel Co-B amorphous alloy catalyst in the form of ultrafine particles was prepared by chemical reduction of CoCl2 with aqueous NaBH4, which exhibited excellent activity and selectivity during the hydrogenation of cinnamaldehyde to cinnamyl alcohol in liquid phase. The optimum yield of cinnamyl alcohol was 87.6%, much better than the yield of using Raney Ni, Raney Co and other Co-based catalysts. 相似文献
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Haibing Guo Hexing Li Jian Zhu Wanhua Ye Minghua Qiao Weilin Dai 《Journal of molecular catalysis. A, Chemical》2003,200(1-2):213-221
A Ru-B amorphous alloy catalyst in the form of ultrafine particles was prepared by chemical reduction of RuCl3 with borohydride in aqueous solution, whose amorphous structure was confirmed by XRD, DSC, and SAED. Heating pretreatment resulted in the rapid crystallization and the deep decomposition of the Ru-B amorphous alloy as well as the abrupt decrease in the surface area due to the gathering of small particles at high temperature. XPS spectra revealed that partial electrons transferred from the alloying B to the metallic Ru in the as-prepared Ru-B sample. In comparison with other catalysts, the as-prepared Ru-B amorphous catalyst exhibited excellent activity and perfect selectivity to
-glucitol as well as superior lifetime during the liquid phase glucose hydrogenation, showing its potential application in industrial process. The higher activity of the Ru-based catalysts than that of other metal catalysts, such as Co-B and Ni-B amorphous catalysts as well as Raney Ni catalysts, demonstrated that the metallic Ru was more active than both metallic Ni and Co for the glucose hydrogenation. Meanwhile, the Ru-B amorphous catalyst exhibited higher activity than its corresponding crystallized Ru-B and pure Ru powder catalysts, showing the promoting effects of both the amorphous structure and the electronic interaction between the metallic Ru and the alloying B, which was briefly discussed based on the kinetic studies and various characterizations. 相似文献
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Substituted alkylcyclohexanones were hydrogenated over several transition metal catalysts. The hydrogenation with freshly prepared Raney Ni gave predominantly the axial alcohols but catalyst to which sodium hydroxide was added or aged catalyst increased the stereoselectivity. In contrast to the PtO2 hydrogenation in which the equatorial alcohols were favoured, more axial alcohols were obtained than the equatorial counterparts on Pt-black. On Pd catalyst the isomeric ratios of the cyclohexanols changed as the reaction progressed. This may be due to a decrease in the amount of hydrogen available caused by the strong adsorption of ketones on the catalyst. Rh catalyst gave more of the axial alcohols than any other catalyst used in the present study. 相似文献
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Raney Ni催化剂是石油化学工业用量最大的催化剂之一,通过急冷技术将其晶态结构转变为非晶态结构,能够提高加氢活性.但非晶态合金热稳定性差、比表面积小限制了这类催化材料的工业应用.通过加入少量稀土元素,使非晶态 Ni 晶化温度提高200 K以上; 通过加入Al再碱抽Al,使非晶态Ni比表面积增加100倍以上; 通过加入功能助剂调节非晶态Ni的加氢选择性、增加抗酸碱腐蚀性和磁性,从而形成了系列非晶态Ni加氢催化剂 (商品名为 SRNA).其中,SRNA-1 用于药物中间体加氢; SRNA-2用于葡萄糖加氢制山梨醇; SRNA-3用于汽、柴油吸附脱硫; SRNA-4用于己内酰胺加氢精制; SRNA-5 用于苯甲酸加氢中替代Pd/C催化剂,使后者的用量减少了50%. 相似文献
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The hydrogenolysis of optically active ethyl 2-amino-2-phenylpropionate (I), its N-methyl (II), and N,N-dimethyl (III) derivatives was studied using Raney Ni and Pd as the catalysts. The Raney Ni catalysed hydrogenolysis of II and III, as well as the reaction catalysed by Pd, occurred predominantly with inversion of configuration; this is not in accord with the hydrogenolysis of corresponding benzyl alcohols. This difference can be ascribed to the difference of the affinity for Ni between N and O atoms. The “SNNi” process may be inhibited in the Raney Ni catalysed hydrogenolysis of II and III since the amino group acts as a self-catalyst poison, and the “SN2” process appears to be preferable to the “SNi” one. The predominance of the configurationally inversion was also observed in the Pd catalysed hydrogenolysis of I. These results over Pd are reasonable in reflecting that the N atom has not so high affinity for Pd. The hydrogenolysis of a quarternary ammonium bromide of I was also reported. 相似文献
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Wilson OM Knecht MR Garcia-Martinez JC Crooks RM 《Journal of the American Chemical Society》2006,128(14):4510-4511
We report a particle size dependence for the rate of hydrogenation of allyl alcohol using 1.3-1.9 nm Pd dendrimer-encapsulated nanoparticle (DEN) catalysts. For particles with diameters of <1.5 nm and containing <147 Pd atoms, the modulation in catalytic activity is due to the electronic properties of the particle. For the larger particles, 1.5-1.9 nm in diameter and containing an average of 147-250 Pd atoms, the size effect is a result of geometrical constraints. Specifically, the hydrogenation reaction is shown to occur preferentially on the face atoms of the larger nanoparticles. 相似文献
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纳米镍在硝基苯加氢中催化性能的研究 总被引:29,自引:0,他引:29
纳米镍在硝基苯加氢中催化性能的研究左东华,张志琨,崔作林(青岛化工学院纳米材料研究所,青岛266042)关键词纳米镍,催化加氢,硝基苯.硝基化合物加氢还原是化工生产中的一个重要化工单元反应,现今工业生产中大多采用Raney-Ni作为催化剂。但由于在R... 相似文献
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A resource recycling technique of hydrogen production from the catalytic degradation of organics in wastewater 总被引:1,自引:0,他引:1
XiaoNian Li LingNiao Kong YiZhi Xiang YaoMing Ju XiaoQiong Wu Feng Feng JunFeng Yuan Lei Ma ChunShan Lu QunFeng Zhang 《中国科学B辑(英文版)》2008,51(11):1118-1126
A resource recycling technique of hydrogen production from the catalytic degradation of organics in wastewater by aqueous phase reforming (APR) has been proposed. It is worthy of noting that this technique may be a potential way for the purification of refractory and highly toxic organics in water for hydrogen production. Hazardous organics (such as phenol, aniline, nitrobenzene, tetrahydrofuran (THF), toluene, N,N-dimethylformamide (DMF) and cyclohexanol) in water could be completely de-graded into H2 and CO2 with high selectivity over Raney Ni, and Sn-modified Raney Ni (Sn-Raney-Ni) or Pd/C catalyst under mild conditions. The experimental results operated in tubular and autoclave reactors, indicated that the degradation degree of organics and H2 selectivity could reach 100% under the optimal reaction conditions. The Sn-Raney-Ni (Sn/Ni=0.06) and Pd/C catalysts show better catalytic performances than the Raney Ni catalyst for the degradation of organics in water into H2 and CO2 by the aqueous phase reforming process. 相似文献