载体比表面积及孔径对Nb_2O_5/α-Al_2O_3催化剂酸性及反应性能的影响  

Effect of Specific Surface Area and Pore Diameter of Support on Acidity and Catalytic Performance of Nb_2O_5/α-Al_2O_3

作　　者：李应成[1] 闫世润[1] 杨为民[2] 谢在库[2] 陈庆龄[2] 贺鹤勇[1] 

机构地区：[1]复旦大学化学系上海市分子催化和功能材料重点实验室,上海200433 [2]中国石油化工股份有限公司上海石油化工研究院,上海201208

出　　处：《石油化工》2006年第3期221-225,共5页Petrochemical Technology

基　　金：国家"973"重大基础研究项目(2003CB615807);上海市科委科研项目(03DJ14004)

摘　　要：采用浸渍法制备了Nb2O5／α—Al2O3催化剂（简称催化剂）并用于环氧乙烷水合制乙二醇的反应，通过控制α-Al2O3载体中致扎剂的含量来调变载体的孔径、孔分布及比表面积；采用吡啶吸附红外光谱、氨程序升温脱附法研究了载体的比表面积及孔径对催化剂酸性及反应性能的影响。实验结果表明，产物的选择性受扩散因素及催化剂酸性的影响，而催化剂的酸最、酸密度可以通过载体的扎径及比表面积的变化加以调控。比表面积较小及孔径较大的载体对催化剂催化环氧乙烷水合制乙二醇的反应较为有利。当载体的比表面积小于0．80m^2／g、孔径为4．00～8．00μm时，在反应温度160℃、反应压力1．5MPa、n（H2O）：n（EO）=22、液态空速25h^-1的条件下，环氧乙烷的转化率大于99．8％，乙二醇的选扦性超过89．9％。Nb2O5 catalysts supported on α-Al2O3 were prepared by impregnation and used in hydration of ethylene oxide （EO）to glycol. Specific surface area and pore diameter of α-Al2O3 support were adjusted by addition of burnout agent. Effects of changes of pore diameter and specific surface area of support on acidic amount, acidic strength and acidic density of catalyst were investigated by means of infrared spectrum of pyridine adsorption and NH3-temperature programmed desorption. Diffusion of both reactants and products, and acidity of catalyst were key factors influencing performance of catalyst. Smaller specific surface area and larger pore diameter of support led to higher acidic density and weaker acidic strength of catalyst while keeping niobium oxide loading same. This status of catalyst was beneficial to EO conversion and selectivity to main product-monoethylene glycol （ MEG ）. When specific surface area was below 0.80 m^2/g and pore diameter was between 4.00 - 8.00 μm,under appropriate conditions： 160 ℃ ,1.5 MPa, n （ H2O） ： n （EO） 22, and liquid hourly space velocity 25 h^-1 conversion of EO and selectivity to MEG could reach 99.8% and 89.9% ,respectively.

关 键 词：环氧乙烷 乙二醇 水合 氧化铌 催化剂 载体 Α-氧化铝 

分 类 号：TQ426.65[化学工程]