The Research Of Metal Modified HZSM-5Zeolite On Reaction Process Of Methanol To Propene

The catalysts performance of HZSM-5modified by different elements on the MTP reaction was systematically studied. Based on the characterization of the modified catalysts, the influence of the catalyst structure and acidity on the catalytic performance was analyzed as well.The catalytic performances of HZSM-5modified with alkali metal K, alkaline-earth metal Ca, Mg, Sr and Ba, rare earth La and Ce, transition metal Co, Fe, Cu, Ni and Zn were experimented respectively. The results showed that the K and Ca modified catalysts had the best selectivity of propylene which increased from25%to32%and33%respectively. The total selectivity of Light olefins varied from each other for different elements modified catalysts, the result is: Ca>K>Mg>Sr>Co>Zn>Ba>Ce>Fe>Cu>La>Ni.Dual-metal modified catalysts were experimented. K, Ca, Fe, Co, Zn and Ce were combined to modify the catalyst through two-step prepare method. The results showed that, the catalyst modified by K-Ca had higher propylene selectivity, enhanced by12%from25%to37%.The catalyst performance after modified by different concentration ratio of K-Ca was further investigated. The results indicated that5%Ca-2%K-HZSM-5catalyst had the best selectivity of propylene, meanwhile, reduced the yield of byproducts and increased the generation of the light olefins. Through the characterization of the catalyst, the result showed that the skeleton structure of the catalyst did not change after modification. The catalyst surface area, pore size and pore volume decreased with the ion concentration increasing. The acidity distribution of the catalyst also changed with different modified condition. In conclusions, suitable acidic sites and certain pore size and pore volume can improve the catalyst performance in the MTP reaction process.