Ti-Si复氧化物载体对金催化剂上丙烯环氧化的影响  

Effect of Ti-Si Mixed Oxide Support on Gold Catalysts for Gas-Phase Epoxidation of Propylene

作　　者：戴茂华[1] 汤丁亮[1] 袁友珠[1] 

机构地区：[1]厦门大学化学化工学院化学系固体表面物理化学国家重点实验室,福建厦门361005

出　　处：《催化学报》2006年第12期1063-1068,共6页

基　　金：国家自然科学基金(20021002;20473065;20433030);福建省科技重大专项(2005HZ01-3)资助项目.

摘　　要：以TiCl4和SiCl4为原料，采用水解和非水水解溶胶-凝胶两种方法制备了一系列不同Ti含量的Ti—Si复氧化物载体，继而用沉积-沉淀法制得载金催化剂．采用X射线衍射、紫外-可见漫反射光谱、N2吸附和高分辨透射电镜对催化剂进行了表征，并考察了催化剂在氢气和氧气存在下的丙烯气相环氧化催化性能．研究表明，钛含量在6％～14％范围内时，两种方法制得的Ti—Si复氧化物均为无定形结构，但采用非水水解溶胶-凝胶法制得的载体比表面积较高．以非水水解溶胶-凝胶法制备的钛含量10％的Ti—Si复氧化物为载体得到的载金催化剂表现出较高的活性和选择性，反应60min时，丙烯转化率为5．7％，240min后降为3．3％，环氧丙烷的选择性稳定于95％左右．还考察了非水水解溶胶-凝胶的陈化时间和金沉积-沉淀溶液的pH值等对反应结果的影响．Titania-silica mixed oxides prepared by TiCl4 and SiCl4 as precursors were employed as the hydrolytic and one-step non-hydrolytic sol-gel routes using gold catalyst supports for gas-phase epoxidation of propylene in O2 and H2. Characterization studies of the supports and catalysts were performed by means of X-ray diffraction, ultraviolet-visible absorption spectroscopy, N2 adsorption, and high-resolution transmission electron microscopy. The results indicated that the amorphous Ti-Si mixed oxides containing 6%-14% of Ti could be prepared by both sol-gel routes, but those by non-hydrolytic sol-gel afforded higher surface area and significant mesopores. A superior catalytic performance was obtained with the gold catalyst supported on the non-hydrolytic sol-gel Ti-Si mixed oxide containing 10% of Ti. The propylene conversion was 5.7% at the initial 60 min and 3.3 % at 240 min of time on stream. The selectivity for propylene oxide was as high as 95 %. The influences of aging time for the non-hydrolytic sol-gel and pH value for the Au deposition-precipitation on the performance of the Au catalyst were also discussed.

关 键 词：非水水解 溶胶-凝胶 氧化钛 氧化硅 复氧化物 金 丙烯 环氧化 环氧丙烷 

分 类 号：O643.32[理学—物理化学]