以化学吸附水解法、蒸氨法和浸渍法制备了Cu/SiO2催化剂,并用于草酸二甲酯氢解制备乙二醇的反应.发现用化学吸附水解法制备的催化剂具有最高的催化活性和乙二醇选择性,乙二醇得率可达92.6%.对还原前后不同方法制备的催化剂进行表征发现,浸渍法制备的催化剂中Cu物种不能很好地得到分散,因此活性较差.蒸氨法和化学吸附水解法能较好地分散Cu物种.由于化学吸附水解法制备的催化剂的Cu^0表面积较蒸氨法的大,且Cu^+表面积相当,故活性高于蒸氨法制备的催化剂.
Cu/SiO2 catalysts have been prepared by the chemisorption-hydrolysis (CH), ammonia evaporation (AE) and wetness impregnation (WI) methods, and evaluated in gas phase hydrogenolysis of dimethyl oxalate (DMO) to ethylene glycol (EG). The Cu/SiO2 catalyst prepared by the CH method showed the highest hydrogenolysis activity and selectivity to EG, giving an EG yield of 92.6%. Characterizations disclosed that Cu species were poorly dispersed on the catalyst prepared by the WI method, which accounts for its poor activity. CH and AE methods could well disperse Cu species, but the CH method resulted in higher Cu^0surface area and comparable Cu^+ surface area as compared to the AE method. As a result, the Cu/SiO2 catalyst prepared by the CH method exhibits the higher hydrogenolysis activity than that by the AE method.