Pd/Al2O3-TiO2催化剂的制备条件

 以含K₂O的Al₂O₃-TiO₂复合物为催化剂载体，考察了浸渍液pH值、浸渍液浓度、浸渍时间和焙烧温度对Pd/Al₂O₃-TiO₂催化剂颗粒的蛋壳厚度、Pd粒子粒径等的影响。采用BET、TEM等方法对所制备的催化剂进行了表征，选择较佳制备条件的Pd/Al₂O₃-TiO₂催化剂进行了C₄馏分选择加氢活性评价。结果表明，随着浸渍液pH值的减小，催化剂颗粒的蛋壳厚度增加；浸渍溶液的浓度越高，浸渍时间越长，越有利于金属在催化剂内层的分布；浸渍液的pH值并不会影响Pd/Al₂O₃-TiO₂催化剂Pd粒子最终的大小。催化剂焙烧温度越高，Pd粒子的平均直径越大，Pd的分散度越小。在反应温度40℃、压力1.5 MPa、体积空速8.0 h^-1、氢/炔摩尔比2.5的条件下，较佳制备条件的Pd/Al₂O₃-TiO₂催化剂催化C₄馏分加氢的炔烃转化率73%、丁二烯选择性85%、丁二烯损失率2.5%。

Preparation Conditions of Pd/Al2O3-TiO2 Catalyst

Al2O3-TiO2 composite containing K2O was used as support for Pd/Al2O3-TiO2 catalyst.The effects of preparation conditions,such as impregnation conditions and calcination temperature on eggshell thickness and size of Pd particle of Pd/Al2O3-TiO2 catalyst were studied.The Pd/Al2O3-TiO2 catalysts were characterized by BET,TEM techniques.The hydrotreating activity of the Pd/Al2O3-TiO2 catalyst prepared under optimal preparation conditions was evaluated with C4 fraction containing alkyne as raw material.Results showed that the eggshell thickness of Pd particle increased with the decrease of pH value of impregnating solution.The higher impregnating solution concentration and longer impregnating time were benefit for endoderm distribution of Pd.The pH value did not affect the size of Pd particles.The higher the calcination temperature,the bigger the Pd particle size is,and the smaller the dispersity of Pd on Pd/Al2O3-TiO2 catalyst.Under the reaction temperature of 40℃,the reaction pressure of 1.5 MPa,LHSV of 8.0 h-1,the H2 to aklyne molar ratio of 2.5,with Pd/Al2O3-TiO2 prepared under the optimal preparation conditions as the catalyst,the alkyne conversion was 73%,selectivity and ratio of loss of butadiene were 85% and 2.5%,respectively,in hydrotreating of alkyne containing C4 fraction.