金属-载体相互作用对CH_4/CO_2重整反应中Rh基催化剂抗积炭性能的影响  

Effect of Metal-Support Interaction on Coking Resistance of Rh-Based Catalysts in CH_4/CO_2 Reforming

作　　者：王锐[1] 刘雪斌[1] 陈燕馨[1] 李文钊[1] 徐恒泳[1] 

机构地区：[1]中国科学院大连化学物理研究所

出　　处：《催化学报》2007年第10期865-869,共5页

基　　金：国家重点基础研究发展计划(2005CB221401)

摘　　要：考察了Rh/Al2O3,Rh/SiO2和Rh/CeO2催化剂上金属-载体间相互作用对CH4/CO2重整反应抗积炭性能的影响,并与反应前后催化剂的程序升温还原和程序升温氧化(TPO)测试结果相关联.实验发现,Rh与Al2O3和SiO2载体间的相互作用越强,催化剂还原后Rh的分散度越高,晶粒越小,高分散的Rh表面生成的碳物种CHx越多,其作为活泼的反应中间体越易与CO2反应生成CO和H2.而游离态的Rh还原后晶粒较大,生成的碳物种与CO2反应能力较低,从而导致催化剂失活.TPO和CO2脉冲实验结果表明,反应过程中Rh/CeO2催化剂上反应生成的CHx物种比Rh/Al2O3和Rh/SiO2上的CHx物种更活泼.同时由于Rh-CeO2间独特的相互作用,部分CeO2还原后生成CeO2-x和氧空位,促进CO2分子的活化解离,导致生成的表面氧容易与CHx反应,从而抑制催化剂积炭.The effects of metal-support interaction on coking resistance of Rh/A12O3, Rh/SiO2, and Rh/CeO2 catalysts during CH4/CO2 reforming were investigated. Temperature-programmed reduction and temperatureprogrammed oxidation （TPO） over fresh and used catalysts suggested that for Rh/Al2O3 and Rh/SiO2, the strong interaction between the metal and support led to a high dispersion of Rh after reduction. The CHx species formed on well-dispersed Rh with small Rh crystals could act as active intermediates to react with CO2 to form CO and H2. On the other hand, the carbon species formed on isolated Rh with large Rh crystals had a relatively low reactivity with CO2, which was attributed to the deactivation of catalysts. For the Rh/CeO2 catalyst, TPO and CO2 pulse experiment results indicated that the CH, species formed were more reactive than those formed on Rh/A12O3 and Rh/SiO2. The unique Rh-CeO2 interaction resulted in the creation of CeO2-x and oxygen vacancies after partial reduction of CeO2, which facilitated the CO2 dissociation. As a result, the dissociated surface oxygen could readily react with CHx. species, thereby inhibiting the carbon deposition over Rh/CeO2.

关 键 词：甲烷 二氧化碳重整 铑 金属 载体相互作用 氧空位 程序升温氧化 

分 类 号：O643.36[理学—物理化学]