可逆与不可逆吸附的CO在甲烷化反应中的作用

THE ROLE OF REVERSIBLY AND IRREVERSIBLY ADSORBED CO IN METHANATION REACTION

在自行设计和建立的加压动态分析装置上,研究了工业甲烷化催化剂(Ni/Al_2O_3)上CO的吸附和反应行为。结果表明,在反应温度250℃下催化剂上吸附的CO有可逆吸附和不可逆吸附之分,甲烷的生成是与不可逆吸附的CO作用的结果,而可逆吸附CO则与生成乙烷、丙烷等密切相关。同时发现甲烷化反应过程的发生必须以不可逆吸附的氢存在为前提,且催化剂上不可逆吸附的氢可分为两部分,一部分可以被CO顶出,这部分氢可能起到了诱导CO吸附的作用;另一部分不可逆吸附的氢不能被CO顶出,这部分氢可能是构成催化剂不可缺少的“组分”(或称“促进剂”)。

Adsorption and reaction of CO on Methanation catalyst(Ni/ Al_2O_3) have been studied with a pressure dynamic analysis equipment. The results show that adsorbed CO on catalyst can be distinguished as reversibly absorbed CO and irreversibly adsorbed CO. The irreversibly adsorbed CO is reponsible for the formation of methane, and the production of ethane and propane etc. are closely related to reversibly adsorbed CO. It is surprising that if the irreversibly adsorbed hydrogen on the surface of the catalyst is desbrbed,the catalyst no longer has methanation activity and can adsorb CO neither. So the part of irreversibly adsorbed hydrogen which can be replaced by CO may be necessary for the adsorption of CO, and the other part of irreversibly absorbed hydrogen which can not be replaced by CO is probaly a kind of promoter for the catalyst. Pressure is shown to be unfavorable for the methanation reaction.