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以正硅酸乙酯为前驱体 ,采用溶胶 凝胶技术将吡啶羧酸钴包埋进SiO2 基体中 ,于 80℃干燥 12h后得到钴含量为2 8% (Co/Si摩尔比 )的干凝胶催化剂 .采用FT IR和TG DTA方法对包埋催化剂进行了表征 ,考察了成胶过程中的pH和水与正硅酸乙酯的摩尔比 (R)对包埋催化剂的结构及其对甲醇氧化羰化制碳酸二甲酯反应催化性能的影响 .结果表明 ,干凝胶催化剂有较高的比表面积 (32 0～ 45 8m2 / g) .在酸性条件下 ,增大 pH或减小R值可缩短成胶时间 .最佳的包埋条件是pH =4,R =6 ,在此条件下制备的凝胶包埋催化剂的活性最高 ,反应 3h ,甲醇转化率为 5 73% ,略低于均相催化剂上的甲醇转化率 .但凝胶包埋催化剂分离简便 ,且重复使用 6次后活性保持不变
Using tetraethyl orthosilicate as a precursor, cobalt picolinate was embedded into the SiO2 matrix by sol-gel technique and dried at 80 ℃ for 12 h to obtain a dry coagulation with cobalt content of 28% (Co / Si molar ratio) The catalysts were characterized by FT IR and TG DTA. The effects of pH and water molar ratio (M) on the entrapped catalyst and the molar ratio of tetraethyl orthosilicate The results showed that the xerogels had higher specific surface area (32 0 ~ 45 8m 2 / g). Under acidic conditions, pH value was increased or R value was decreased Can shorten the gelling time.The best embedding conditions are pH = 4, R = 6, under the conditions of the gel-embedded catalyst prepared the highest activity, the reaction 3h, the methanol conversion rate of 5 73%, slightly lower than Methanol conversion on the homogeneous catalyst However, the gelation of the gel-embedded catalyst is easy and the activity remains unchanged after 6 repeated uses