咪唑/镍(Ⅱ)改性SAPO-34的制备及其催化CO_2加氢制备乙烯  

Imidazole and Nickel (Ⅱ) Modified SAPO-34 and Its Catalytic Activity in CO_2 Hydrogenation to Ethylene

作　　者：唐小华[1] 李辉[1] 杨爱梅[1] 查飞[1] 常玥[1] 

机构地区：[1]西北师范大学化学化工学院,兰州730070

出　　处：《无机材料学报》2017年第11期1209-1214,共6页Journal of Inorganic Materials

基　　金：国家自然科学基金(21161017)~~

摘　　要：按异丙醇铝:磷酸:硅溶胶:四乙基氢氧化铵:水:改性剂=1.0:0.8:0.6:2.0:52:0.01的质量比,先将异丙醇铝和磷酸溶于水,再加入硅溶胶和四乙基氢氧化铵的混合液,30℃搅拌4 h后加入摩尔比为1:1的咪唑和硝酸镍,60℃搅拌8 h,室温陈化24 h,在不锈钢水热合成反应釜中200℃晶化24 h,固体在120℃干燥12 h,550℃焙烧6 h,制得咪唑/镍(Ⅱ)改性SAPO-34分子筛。用X射线粉末衍射(XRD)、扫描电镜(SEM)、能量色散X射线(EDS)和N2吸脱附对咪唑/镍(Ⅱ)改性SAPO-34进行了表征。将改性后的SAPO-34分子筛与CuO-ZnO-Al_2O_3按质量比1:1机械混合制备了复合催化剂。在固定床微分反应器上测定了复合催化剂对CO2加氢制备低碳烯烃的催化性能。在温度400℃,压强3.0 MPa,碳氢体积比为1:3,空速为1800 m L/(gcat·h),复合催化剂用量为1.0 g时,二氧化碳的转化率达到73.8%,乙烯的选择性为67.7%,显示了较高的催化活性,并且当温度继续升高至450℃时,乙烯的选择性并未下降,显示了一定的耐高温性能。Imidazole and nickel（Ⅱ） modified SAPO-34 was synthesized according to the mass ratio of aluminumisopropoxide： phosphoric acid： silica sol： tetraethylammonium hydroxide ： water ： modified agents = 1.0 ： 0.8 ： 0.6 ：2 ： 52 ： 0.01. Specified amount of aluminum isopropoxide was mixed with distilled water and phosphoric acid was added to present the white homogenous gel. Tetraethylammonium hydroxide was Also mixed with specified amount of silica sol to form homogenous solution. The homogenous solution was added to the white homogenous gel. After stirring at 30℃ for 4 h, specified amount of imidazole and nickel nitrate（mole ratio = 1 ： 1） was added in and kept at 60℃ with a constant stirring speed for 8 h to result in a semi-transparent homogenous white gel. The white gel was transferred into a high-pressure stainless steel autoclave and maintained at 200℃ for 24 h without stirring. As precipitate was recovered from the autoclave, it was dried at 120℃ for 12 h and calcined at 550℃ for 6 h to acquire imidazole and nickel modified SAPO-34. It was characterized by means of N2 adsorption/desorption, X-ray powder diffraction（XRD）, scanning electronic microscopy（SEM）, and energy dispersive spectroscopy（EDS）. The modified SAPO-34 was mechanically mixed with CuO-ZnO-Al_2O_3 prepared by co-precipitation process to form composited catalyst（CZA/SAPO-34 x）. The activity of CZA/SAPO-34 x for CO_2 hydrogenation to light olefins was investigated in a differential fixed reactor. Under reaction pressure of 3.0 Mpa, temperature of 400℃, space velocity（SV） of 1800 m L/（gcat·h）, volume ratio of CO_2 to H_2 of 1 ： 3, and composited catalyst mass of 1.0 g, the one-way conversion of CO_2 and selectivity of ethylene are 73.8% and 67.7%, respectively. Compared with SAPO-34, imidazole and nickel（Ⅱ） modified SAPO-34 keeps high catalytic activity when reaction temperature rises to 450℃, showing the high temperature resistance.

关 键 词：SAPO-34分子筛 复合催化剂 二氧化碳加氢 乙烯 改性 

分 类 号：TQ426[化学工程]