Mo/HZSM-5催化剂上甲烷脱氢芳构化反应——催化剂蒸汽处理的影响  

Methane Dehydroaromatization over Mo/HZSM-5 Catalysts:Effect of Streaming-treatment

作　　者：宋一兵[1] 方奕文[1] 李谦和[2] 

机构地区：[1]汕头大学化学系,中国汕头515063 [2]湖南师范大学化学化工学院,中国长沙410081

出　　处：《湖南师范大学自然科学学报》2007年第2期91-95,共5页Journal of Natural Science of Hunan Normal University

基　　金：国家自然科学基金资助项目(20203012);广东省自然科学基金资助项目(06027250)

摘　　要：对机械混合法制备的Mo/HZSM-5催化剂进行蒸汽后处理,利用XRD、XPS等表征催化剂的晶相结构、Mo物种的分散度,在关联催化剂活性评价基础上,研究了催化剂的蒸气处理过程对Mo物种的分散度及其芳构化反应性能的影响.结果表明,机械混合法制备的催化剂上,Mo物种主要以微晶的形式分布在分子筛的外表面,由于缺少分子筛孔道择形保护,便于积炭副反应的发生.经高温蒸气处理后,催化剂上Mo物种的分散度显著提高,有较多的Mo物种迁移至分子筛的孔道内,并与B酸发生强相互作用生成钼氧二聚体,有效地增强了催化剂的抗积炭能力.因此,蒸气处理的Mo/HZSM-5催化剂的芳烃选择性和催化稳定性较传统机械混合法制备的催化剂有明显提高.A streaming treatment was employed to modify mechanically mixed Mo/HZSM-5 catalyst, and the crystal phase compositions and Mo dispersion were investigated by XRD, XPS techniques. It was found that the catalytic performance of Mo/HZSM-5 catalyst in methane dehydroaromatization （MDA） has strongly dependent on the dispersion of Mo species on the HZSM-5 zeolite. On the mechanically mixed Mo/HZSM-5 catalyst, the Mo species mainly existed as MoO3 crystallites on the external surface of the zeolite. Without protection by the shape-selective environment within zeolite channels, the Mo crystallites promoted the coke formation during the MDA reaction. After subjected to the streaming treatment, the dispersion of the loaded Mo species pronouncedly increased, and some Mo species with small particle size migrated into the zeolite channels and reacted with the Broensted acid sites to form （Mo2O5）^2＋ dimers. Thus, a remarkable improvement in catalytic durability and selectivity to aromatics was achieved on the streaming-treated Mo/HZSM-5 catalyst compared with the mechanically mixed catalysts, mainly due to effective suppression of coke formation during the DMA reaction.

关 键 词：甲烷 脱氢芳构化 蒸汽处理 MO/HZSM-5 

分 类 号：O543[理学—物理]