摘要
选用不同的碱土金属氯化物为原料,采用共研磨的方法制备出了具有不同表面碱性的MCl2-TiO2-SnO2(M=Mg,Ca,Sr,Ba)催化剂,并考察了催化剂的甲烷氧化偶联反应性能.通过N2吸脱附(BET)、X-射线衍射(XRD)、X-射线光电子能谱(XPS)和CO2程序升温脱附(CO2-TPD)等技术对催化剂进行了表征.结果表明,随碱土金属元素的不同,催化剂呈现出了强弱不同的碱性吸附位.催化剂表面的碱性对活化甲烷具有促进作用,同时也带来乙烯深度氧化副反应的发生.碱量越大的弱碱性吸附位对甲烷的活化越有利,而强碱性吸附位则能导致催化剂活性降低,甚至是催化剂失活.乙烯的选择性与催化剂表面晶格氧的相对浓度密切相关.表面晶格氧的相对浓度较高的催化剂,其乙烯选择性也较大.
The performance of MCl2-TiOz-SnO2 （ M = Mg, Ca, Sr, Ba） catalysts in oxidative coupling of methane reaction has been investigated. The catalysts were prepared by grinding method, and characterized by BET, XRD, XPS and CO2-TPD, respectively. The distribution of surface basicity strength is varied with the changing of Mz＋ in the catalysts. The more weak basic sites on catalyst surface are crucial for the activation of methane; while the strong basic sites bring the loss of active sites on catalyst surface. In addition, although the basic site can prompt the conversion of methane, it can also bring the deep oxidative of ethylene. The lattice oxygen is selective to ethylene product generation, and the selectivity to ethylene increase with increasing relative concentration of surface lattice oxygen.
出处
《分子催化》
EI
CAS
CSCD
北大核心
2013年第2期152-158,共7页
Journal of Molecular Catalysis(China)
