炭载体对乙炔氢氯化反应金催化剂催化性能的影响

Impact of carbon support on gold catalyst performance for acetylene hydrochlorination

以氯金酸为前体,不同孔结构的活性炭为载体,采用等体积浸渍法制备负载型金催化剂,用于乙炔氢氯化反应,发现载体孔结构对反应活性及选择性影响显著。具有适当微孔孔径的活性炭负载的金催化剂,其活性及选择性较好;微孔孔径太小不利于气体扩散,乙炔转化率低;中孔丰富微孔少的载体,虽然转化率较高但氯乙烯选择性下降,产物中出现二氯乙烷。3种催化剂最佳反应温度都低于160℃,但稳定性较差,400min内转化率都低于10%。程序升温还原(TPR)结果表明,Au3+与活性关系密切。用电感耦合等离子原子发射光谱(ICP-AES)测定了样品中的金含量,用氮吸附方法测定了载体和催化剂的比表面积(BET)和孔结构,用透射电子显微镜(TEM)研究了催化剂样品的形貌。

Supported gold catalysts were prepared by incipient wetness impregnation method using chloroauric acid as precursor and active carbon with different pore structure as supports.The catalytic performance was investigated for acetylene hydrochlorination.It was found that the catalytic activity was remarkably influenced by the pore structure of support.Catalyst on a support with a proper micropore size exhibited a superior activity and selectivity for vinyl chloride,and that on a support with a smaller micropore size exhibited a lower activity,which is probably due to the diffusion hindrance.While,the catalyst on a support with full mesopores showed a medium activity and low selectivity for vinyl chloride,dichloroethane was observed in the product.The optimum reaction temperature of the three catalysts was lower than 160℃,but the catalyst stability was inferior.The conversion of acetylene decreased dramatically with running time and was less than 10% in 400 min for all the three catalysts.TPR results showed that the Au3＋ in the catalyst has close relation to the catalytic activity.Inductively coupled plasma atomic emission spectrometry（ICP-AES）was used to measure the gold content in the catalyst.Nitrogen adsorption-desorption method was used to investigate the specific surface area（BET area）and pore structure of the catalyst.Transmitted electronic microscopy（TEM）was used to observe the morphology of the catalyst samples.