Temperature-programmed Reduction of Metal-exchanged Zeolite-a Catalysts

The reduction of metal (Co, Ni, and Cu)-exchangedzeolite-A was studied by a temperature programmed reduction (TPR) technique. The TPR profiles indicate that the metals are in a dispersed form. The hydrogen consumption in the reduction process demonstrates that the metals are present in monovalent and divalent forms. High-temperature reduction peaks are also observed in the cases of CoA and NiA. Nitrogen adsorption reveals that, on heating at high temperature, the pore capacity of zeolite-A increases when exchanged with transition metals because more space is occupied by water molecules. This is confirmed by thermal analysis. After dehydration, the cations are in changed positions; they are often located in hidden sites (hexagonal prism and sodalite cages). The activation energy for the reduction process is calculated. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of Cr and Co Promoters Addition on Vanadium Phosphate Catalysts for Mild Oxidation of n-Butane

In this study, Cr and Co promoted, as well as unpromoted vanadium phosphate (VPO) catalysts were synthesized by the reaction of V2O5 and o-H3PO4 in organic medium followed by calcination in n-butane/air environment at 673 K. The physico-chemical properties and the catalytic behavior were affected by the addition of Cr and Co dopants. H2-TPR was used to investigate the nature of oxidants in the unpromoted and promoted catalysts. The results showed that both the Cr and Co promoters remarkably lowered the temperature of the reduction peak associated with V5 . The amount of oxygen species originated from the active phase, V4 , removed was significantly increased for Co and Cr-promoted catalysts. Both Cr and Co dopants improve strongly the n-butane conversion without sacrificing the MA selectivity. A good correlation was observed between the amount of oxygen species removed from V4 phase and the activity for n-butane oxidation to maleic anhydride. This suggested that V4 -O was the center for the activation of n-butane.     

Characterization of Ru/CeO2-Al2O3 catalysts and their Performance in CO2 Methanation

Ru/Al₂O₃ and Ru/CeO₂-Al₂O₃ samples were used as catalysts in CO₂ methanation. The catalysts were characterized by temperature-programmed reduction (TPR) and X-ray diffraction. The promoting effect of ceria on the cataytic activity of the catalysts under study in CO₂ methanation was observed.     

Fe－ZSM－5分子筛中Fe的化学环境研究

本文应用ＥＳＲ、ＸＰＳ、ＤＲＳ、Ｍｏｓｓｂａｕｅｒ谱和首次运用ＴＰＲ技术结合ＸＰＳ、ＸＲＤ对Ｆｅ－ＺＳＭ－５中Ｆｅ的化学环境进行了研究。结果表明，碱性介质条件下合成的Ｆｅ－ＺＳＭ－５分子筛中，铁仅有一种价态Ｆｅ（Ⅲ），但却有多种存在形式。非骨架Ｆｅ（Ⅲ）包括分子筛孔道内及外表面上沉积的氧化铁；骨架Ｆｅ至少有两种状态，即骨架不饱和配位Ｆｅ（Ⅲ）和骨架畸变四配位的Ｆｅ（Ⅲ）．各种测试方法的结果表明Ｆｅ主要位于分子筛的骨架上，非骨架Ｆｅ（Ⅲ）很少．     

Pd/Ce/Al/蜂窝陶瓷催化剂制备方法的研究

本文应用溶胶－凝胶技术对蜂窝陶瓷表面进行涂层,然后负载活性组分,以CO氧化作模型反应,考察了催化剂干燥方法,浸涂原液类型以及助剂CeO2对汽车尾气净化催化剂活性的影响,并应用TPR、XPS等手段对其进行表征,由催化剂活性测试结果表明,干燥方法对催化剂活性影响不大,加入分散剂的氧化铝溶胶作浸渍原液的催化活性最高,同时活性评价实验结果还表明,加入CeO2作助剂的催化剂的活性明显提高,这可能是由于PdO与CeO2之间发生的协同效应所致,XPS谱图结果显示,CeO2与PdO之间存在协同作用,且Pd处于较高的氧化状态,这可能起因于从Pd到Ce的电子转移作用,Ce处于较低的还原状态,导致Ce-O键结合强度的降低。H2－TPR表征结果同样证实了PdO与CeO2之间存在协同效应,CeO2的引入,促进了PdO的还原,而PdO的存在降低了CeO2表面氧的还原温度,同时此现象也支持了XPS结论。     

Co Oxidation Activity And Tpr Characterization Of Ag-Mn Complex Oxide Catalysts

A series of Ag-Mn complex oxides was prepared by co-precipitation method and used for carbon monoxide oxidation. The catalysts were characterized by means of XRD and H₂-TPR techniques. A synergistic interaction between silver oxide and manganese oxide is responsible for the high activity of carbon monoxide oxidation at low temperature.     

TPR鞋用材料

分析了TPR鞋用材料的配方、工艺、性能 .实验结果表明 ,该材料具有高弹性、耐低温、粘结强度牢等特点 ,适用于生产中高档运动鞋和旅游鞋鞋底 .     

混合硝酸镍和醋酸镍制备的催化剂的特征和催化加氢抗硫性能

使用直接还原镍盐前体[Ni(NO_3)_2/γ-Al_2O_3, NiAc_2/γ-Al_2O_3或Ni (NO_3)_2-NiAc_2/γ-Al_2O_3]和镍氧化物前体的方法制备催化剂,研究了它们的 表面特征和甲苯加氢抗硫性能。还原镍盐得到的催化剂比还原其焙烧成的氧化物制 得的催化剂金属的还原和分散程度高。Ni(NO_3)_2-NiAc_2/γ-Al_2O_3分解得到的 氧化物前体的TPR在约415 ℃出现了较小数量的块状NiO的还原峰;而Ni(NO_3)_2- NiAc_2/γ-Al_2O_3的TPR中镍盐分解成氧化物时的耗氢量变小。用氢溢流的概念和 镍盐分解时的耗氢量可以将TPR的结果和金属的分散性关联起来。在镍盐前体催化 剂上甲苯的加氢具有较高的活性,而两种盐摩尔比为1：1时,盐前体催化剂反应活 性出现了一极大值,同时盐和氧化物前体催化剂都给出了抗硫性能的极大值。     

Preferential oxidation of CO in excess H2 over the CeO2/CuO catalyst： Effect of initial support

Three series of CeO2/CuO samples were prepared by impregnation method and characterized by XRD, N2adsorption-desorption, temperatureprogrammed reduction(TPR), XPS and TEM techniques. In comparison with the samples prepared with CuO as initial support, the samples with Cu(OH)2as initial support have higher reducibilities and smaller relative TPR peak areas, and also larger specific surface areas at calcination temperatures of 400℃–600℃. As a result, Cu(OH)2is better than CuO as initial support for preferential oxidation of CO in excess H2(CO-PROX). The best catalytic performance was achieved on the sample calcined at 600℃ and with an atomic ratio of Ce/Cu at 40%. XPS analyses indicate that more interface linkages Ce-O-Cu could be formed when it was calcined at 600℃. And the atomic ratio of Ce/Cu at 40%led to a proper reducibility for the sample as illustrated by the TPR measurements.     

富氧条件下NO_x的选择催化还原:载体与活性组分的影响

考察了不同载体 ,如微孔沸石 P、ZSM- 5和 Beta,中孔材料 MCM- 41以及 γ- Al2 O3 等负载Co催化剂在富氧条件下对丙烷选择性催化 NOx 还原的活性 .用 N2 吸附等温线、程序升温还原( TPR)及 X光光电子能谱 ( XPS)等方法表征了载体的孔结构和 Co的化学态并与反应活性关联 .结果表明 :载体的结构和孔道以及 Co组分的化学态决定了 NOx 选择催化还原活性 ,催化剂对 NOx催化转化活性次序如下 :Co/Beta>Co/ZSM- 5 Co/P≌ Co/γ- Al2 O3 >Co/MCM- 41 ,适宜的孔径以及保持 Co组分在孔道内为 Co2 + 结构是 Co/Beta活性最高的主要原因