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采用盐酸回流法和氨水沉淀法合成了氧化铝载体,并通过络合真空浸渍法制备了不同来源氧化铝负载的Pt-Sn-K/γ-Al2O3催化剂。利用N2物理吸附、CO脉冲吸附、H2程序升温还原、NH3程序升温脱附、热重等手段对Pt-Sn-K/γ-Al2O3催化剂进行了表征,以异丁烷脱氢为探针反应研究了氧化铝载体对该催化剂脱氢性能的影响。结果表明,与由盐酸回流法合成的载体制备的催化剂相比,采用氨水沉淀法合成的氧化铝载体制备的Pt-Sn-K/γ-Al2O3催化剂表面具有较小的Pt颗粒和较弱的酸性分布,其脱氢活性及异丁烯选择性更优。14 d的连续运行数据显示,由氨水沉淀合成的载体制备的催化剂,其抗积炭能力更强,反应后催化剂的积炭石墨化程度更低,因而具有更好的稳定性;在该催化剂上,异丁烷初始转化率为56.67%,14 d后仍能达到34.71%,异丁烯初始选择性为80%,7 d后维持在94%左右。 相似文献
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Yiwei Zhang Yuming Zhou Lihui Wan Mengwei Xue Yongzheng Duan Xuan Liu .School of Chemistry Chemical Engineering Southeast University Nanjing Jiangsu China .Biochemical Environmental Engineering College Nanjing Xiaozhuang University Nanjing 《天然气化学杂志》2011,20(6):639-646
Catalytic dehydrogenation of isobutane has recently received considerable attention because of the increasing demand for isobutene.In this study,the synergistic effect between Sn and K on PtSnK/γ-Al2O3 catalysts has been investigated by changing the content of Sn.It was found that with the presence of potassium,suitable addition of Sn could not only increase the metal dispersion,but also reduce the catalyst acidity.In these cases,the synergistic effect could also strengthen the interactions between the metal and support,which resulted in an increase in both catalytic activity and stability.In our experiments,Pt-0.6SnK/Al catalyst exhibited the lowest deactivation rate (12.4%) and showed a selectivity to isobutene higher than 94% at the isobutane conversion of about 45.3% after running the reaction for 6 h.However,with the excessive loading of Sn,surface property of active sites and the interactions between metal and support were changed.As a result,the initial optimal ratio between the metallic function and acid function would be destroyed,which was disadvantageous to the reaction. 相似文献
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钒钼复合氧化物表面上激光促进异丁烷选择氧化制甲基丙烯酸 总被引:4,自引:0,他引:4
用共沉淀法制备了V和Mo的复合氧化物,运用XRD、IR、TPD和LSSR技术研究了其晶体结构、表面构造、化学吸附特性和激光促进异丁烷选择氧化反应性能。结果表明:V-Mo-O的主体物相为Mo4V6O24,它具有MoO3和V2O4交替排列的层状结构,其表面上存在着Lewis碱位Mo=O和Mo-O-V键中的O^2-及Lewis以位V^4 ;异丁烷的2个甲基H分别吸附在2个相邻的Lewis碱位Mo=O上形成双位分子吸附态;在常压和200℃条件下,用一定频率的激光激发Mo=O键1000次,异丁烷的转化率为6.5%,其反应产物是异丁烯、甲基丙烯醛和甲基丙烯酸,其中甲基丙烯酸的选择性为78%。根据实验结果,探讨了激光促进异丁烷选择氧化为甲基丙烯酸的表面反应机理。 相似文献
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T. V. Vasina O. V. Masloboishchikova E. G. Khelkovskaya-Sergeeva L. M. Kustov P. Zeuthen 《Russian Chemical Bulletin》1999,48(7):1270-1273
Isomerization ofn-butane on various types of zeolites (ZVM, ZVK, mordenite, and Y) modified with transition metals and cationic and anionic
additives was investigated. Under the conditions studied, H-forms of zeolites are inactive. Pt-containing systems based on
the H-form of ZVM (HZVM) are the most efficient catalysts forn-butane isomerization, and the yield of isobutane reaches 20–26 wt.% at a selectivity of 40–45%. Modification of this catalyst
with Ga and Fe compounds or with an aqueous solution of HCl increases the selectivity with respect to isobutane up to 70–90%.
Introduction of Zn2+ cations or F− and SO4
2− anions into the Pt-containing HZVM system decreases the selectivity and yield of isobutane due to the formation of very strong
acidic centers on which disproportionation and hydrocracking ofn-butane mainly occur.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1281–1285, July, 1999. 相似文献
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Yan Huang Yaan Cao Guojia Wang Vicente Cortes Corberan 《Reaction Kinetics and Catalysis Letters》2002,75(1):31-37
A novel type of catalysts, KF-TiO2, efficient for the oxidative dehydrogenation (ODH) of isobutane is presented. The effect of KF content and calcination temperature was studied. In the reaction conditions explored, the best performance (73 % selectivity to isobutene at 10.5 % conversion of isobutane) was observed over a catalyst with KF/TiO2 = 0.2 (mol/mol). The surface properties of the catalysts were investigated by SPS (Surface Photo-voltage Spectroscopy) and XPS. The promotion effect of KF in the catalysts can be attributed to the formation of an oxyfluoro-compound, K2Ti4O8F2. 相似文献
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Cristina R. Dias Rodica Zãvoianu M. Farinha Portela 《Reaction Kinetics and Catalysis Letters》2002,77(2):317-324
The acid-base properties of several NiMoO4 catalysts supported on two silicas and prepared by different methods have been studied by temperature-programmed desorption of NH3. The catalytic behavior in the oxidative dehydrogenation of isobutane for two NiMoO4 catalysts with different acid-base properties are compared. 相似文献