CO+H2直接制取低碳烯烃催化剂的研制与评价

Preparation and evaluation of Fe-MnO/zeolite catalystsfor hydrogenation of carbon monoxide to light olefins

通过碱改性酸性强、孔道择形性好的ZSM-5沸石分子筛,可清除其酸性,抑制低碳烯烃因沸石酸中心引起的二次反应,从而提高了低碳烯烃选择性;沸石经碱改性后增强了催化剂碱度,从而提高了CO转化率,碱性环境还有利于烯烃生成。为此,在弱酸性的高硅沸石担载型催化剂中添加碱性助剂,大大提高了催化剂活性及C_2=～C_4=烯烃选择性(其活性顺序为:K>Na>Li),从而研制出了C_2=～C_4=占烃类选择性达60%,CO转化率达70%的K-DM-Ⅱ型催化剂。

By modifying ZSM-5 zeolite with alkalies,its strong acid sites can be eliminated and consequently the secondary reactions of light olefins on the acid sites are inhibited and the selectivity of C_2=～C_4=are enhanced. Furthermore, the basic properties of the catalysts became strong with its modification with alkali,as the catalytic activity is so enhanced and the basic environment is favourable for the yield of light olefins. For Si-zeolite, having weaker acidic property, supported catalysts, the cataytic activity and C_2=～C_4=selectivity are both improved obviously by adding alkali promoter,with an order of K>Na>Li. On the basis of above results,K-DM-Ⅱ catalyst with a selectivity of 60% C_2=～C_4=and a conversion of 70% CO is obtained.