Cu/AC催化剂制备方法对气相甲醇氧化羰基化的影响

摘要

Supported chlorine-free Cu/activated carbon (AC) catalysts were prepared by the methods of impregnation and deposition-precipitation with Cu(NO3)2 and Cu (CH3COO)2,respectively.Effect of preparation methods on structure and catalytic performance of vapor phase oxidative carbonylation of methnol was studied.The results show that catalyst Cu/AC-D prepared by deposition-precipitation with Cu(NO3)2 exhibits CuO and Cu2O as the main copper species,and low catalytic performance.Catalyst Cu/AC-A prepared by impregnation method with Cu(CH3COO)2 shows the main copper species was Cu0,and the catalytic performance increased remarkably.Catalyst Cu/AC-N prepared by impregnation method with Cu(NO3)2 exhibits Cu0 as the main copper species,with small amount of Cu2 O and CuO species.And this method promoted reduction temperature shifting to low temperature,decreased the particle size of Cu0,and increased the desorption capability of CO.As a result,Catalyst Cu/AC-N exhibited the highest activity,with the selectivity and space-time yield of DMC reached 83.3％ and 177.0 mg/(g · h),respectively,and the average inactivation rate is only 0.25％/h during 200 h running time.%以醋酸铜和硝酸铜为铜源,分别采用浸渍法和沉积沉淀法制备了活性炭(AC)负载型无氯Cu/AC催化剂,并考察了制备方法对催化剂微观结构及气相甲醇氧化羰基化反应的影响.结果表明,以硝酸铜为铜源,采用沉积沉淀法制备的Cu/AC-D催化剂中Cu物种以CuO和Cu2O为主,活性低；采用醋酸铜溶液浸渍活性炭制备的Cu/AC-A催化剂中Cu物种以单质Cu0的形式存在,活性大幅提升；以硝酸铜溶液浸渍活性炭制备的Cu/AC-N催化剂中Cu物种以单质Cu0为主,并存在一定量的Cu2O和CuO物种,该方法制备的催化剂中CuO和Cu2O还原温度低,Cu晶粒尺寸小,CO的低温吸附能力强,催化活性高,碳酸二甲酯的选择性和时空收率分别达到83.3％和177.0mg/(g·h),200h内平均失活率仅为0.25％/h.