Co-Mo/HZSM-5甲烷无氧芳构化催化剂上的积炭

Characterization of Coke on Co-Mo/HZSM-5 Catalyst for Methane Dehydro Aromatization in the Absence of Oxygen

考察了Co Mo/HZSM 5催化剂对甲烷芳构化反应的催化性能及催化剂上的积炭 .采用碳数平衡计算法和TG法得出的平均积炭速率比较接近 ,在不同空速下 ,36 0min内 ,催化剂上的积炭量都接近 5 % .对烧炭TG曲线的分析结果表明 ,积炭量约为 5 %时 ,积炭能分散于分子筛表面 .在高空速下 ,积炭容易沉积在分子筛的外表面 ;在低空速下 ,积炭容易沉积在分子筛的内表面 .在空速 30 0 0ml/(g·h)下积炭时 ,其烧炭动力学过程符合一级反应过程 ,烧炭活化能为 140 8kJ/mol.

The catalytic performance of Co Mo/HZSM 5 catalyst for methane dehydro aromatization was investigated and the coke formed during the reaction at different space velocity was studied by TG method. The coke formation rates calculated based on the carbon balance of reaction are in reasonable agreement with those measured by TG method. Under all the reaction conditions used in this work, the total amount of coke formed is less than 5%. Based on the analysis of TG curves, it is suggested that the coke is dispersed on/in Co Mo/HZSM 5 catalyst, and that the coke formed at high space velocity prefers to deposit on the external surface, while it preferentially deposits in the zeolite channels at low space velocity. At the space velocity of 3?000 ml/(g h), the kinetics of coke combustion fits in first order reaction with respect to coke amount, and the corresponding activation energy is about 140 kJ/mol.