H_2对Rh-Mn-Li-Ti/SiO_2催化剂上CO吸附和脱附的影响  

Effect of H_2 on Adsorption and Desorption Behavior of CO over Rh-Mn-Li-Ti/SiO_2 Catalyst

作　　者：陈维苗[1] 丁云杰[1] 王涛[1] 江大好[1] 李显明[1] 罗洪原[1] 

机构地区：[1]中国科学院大连化学物理研究所,辽宁大连116023

出　　处：《催化学报》2005年第12期1099-1103,共5页

基　　金：国家重点基础研究发展规划资助项目(G1999022404)

摘　　要：应用红外光谱和程序升温脱附技术研究了Rh-Mn-Li-Ti/SiO2催化剂上H2对CO吸附和脱附的影响.结果表明,预吸附的H2主要占据线式CO的吸附位.共吸附时H2与CO在Rh位上形成了羰基氢化物,从而导致线式物种谱带红移,且高的H2浓度有利于CO的吸附.在323 K下,H2对预吸附的CO谱带位置和强度没有影响.但是,随着温度的升高,H2的存在促进了弱吸附CO的脱附,并使之重新吸附;同时,H2促进了强吸附CO的解离,增强了CO的吸附强度和催化剂的吸附能力.The effect of H2 on the adsorption and desorption behavior of CO on the Rh-Mn-Li-Ti/SiO2 catalyst was examined by IR spectroscopy and temperature-programmed desorption. The results indicated that the preadsorbed H2 mainly occupied the adsorption sites for linearly adsorbed CO, and the part of subsequently adsorbed CO reacted with adsorbed hydrogen producing carbonyl hydrides. In the mixture of CO and hydrogen,carbonyl hydrides were also formed on Rh sites causing the red shift of the IR band of linearly adsorbed CO, and the high hydrogen concentration enhanced the CO adsorption. At 323 K, the IR band position and intensity of pre-adsorbed CO were not sensitive to the hydrogen. However, with increasing temperature, the presence of hydrogen promoted the desorption of weakly adsorbed CO, and its re-adsorption, as well as the dissociation of strongly adsorbed CO. In addition, the existence of hydrogen intensified the CO adsorption and influenced the structure of Rh giving rise to the increase in Rh dispersion and thereby the amount of CO adsorbed on Rh at 323 K.

关 键 词：红外光谱 程序升温脱附 铑 锰 锂 钛 氧化硅 负载型催化剂 氢 一氧化碳 吸附 脱附 

分 类 号：O643.32[理学—物理化学]