Catalytic Combustion of Dichloromethane over Cr-13X and K-Cr-13X Zeolites Catalysts
ZHANG Lilei;LIU Shaoying;LI Zijian;YAO Jie;WANG Gongying;Chengdu Institute of Organic Chemistry,Chinese Academy of Sciences;University of Chinese Academy of Sciences;
Cr-13X and K-Cr-13X zeolites catalysts with different K and Cr contents were prepared by ion exchange method,and their catalytic performance for catalytic combustion of dichloromethane were evaluated in a conventional fixed bed reactor. Then,these catalysts were characterized via physicochemical techniques. The results showed that,when the Cr content was less than 5. 19%,crystallinity of 13X zeolite was not affected by the addition of K and Cr significantly. Cr addition not only enhanced the selectivity of CO2product,but also eliminated CH3Cl by-products. The exchange of K with an appropriate amount enhanced the stability and activity of Cr-13X catalyst,as well as the selectivity of CO2and HCl products. The enhancement of the catalytic activity and the products distribution could be accounted for the basis of oxidation and acidity of catalysts. On the condition of gas hourly space velocity of 1 × 104h- 1and dichloromethane concentration of 5692 mg/m3,an optimal 1. 31%K-5. 01%Cr-13X catalyst was found with t50at 212 ℃,t98at 298 ℃,CO2selectivity at 60. 6% and HCl selectivity at 96. 5%,and this catalyst showed relatively stable catalytic activity during 100 h reaction.