Na离子修饰的Au/HZSM-5催化剂的制备、表征及催化合成气羰基化反应性能

Preparation,Characterization and Catalytic Performance in Carbonylation of Syngas of Na Ion Modified Au/HZSM-5 Catalyst

采用负压沉积-沉淀法制备了负载型Au/HZSM-5催化剂,在此基础上负载了第二金属Na制得Na-Au/HZSM-5催化剂,采用XRD、ICP-AES、氮气吸附-脱附、NH 3-TPD、OH-IR、Py-FT-IR等方法对Na/HZSM-5、Au/HZSM-5、Na-Au/HZSM-5物性进行分析,并考察酸中心对其催化合成气羰基化反应性能的影响。结果表明:2.0%Au/HZSM-5催化剂上加入少量Na离子后,催化剂的酸性变化较大,Na负载质量分数为0.4%时大幅度减弱了强酸中心,并产生了一定量的中强酸;对不同Au/HZSM-5催化剂的性能进行对比,当Au离子负载质量分数为2.0%时,2.0%Au/HZSM-5催化剂上CO转化率为81.01%,甲酸甲酯+乙酸甲酯的选择性之和为62.12%;而0.4%Na-2.0%Au/HZSM-5催化剂上CO转化率最高,为88.51%,甲酸甲酯+乙酸甲酯的选择性之和为68.56%。Na离子改性后中强酸中心的增加和强酸中心的减弱可提高Au/HZSM-5催化合成气羰基化反应中CO转化率和目的产物的选择性。

The supported Au/HZSM-5 catalyst was prepared by negative pressure deposition precipitation method,and modified by Na ions.And the effects of acid centers on catalytic performance in the syngas carbonylation reaction were investigated.The physical and chemical properties are characterized by XRD,ICP-AES,N 2 adsorption-desorption,NH 3-TPD,OH-IR and Py-FT-IR.Results show that adding small amount of Na ions to Au/HZSM-5 significantly changes catalyst acidity.When the Na mass fraction is 0.4%,the strong acid center becomes significantly weakened and a certain amount of medium strong acid is produced.When Au ion mass fraction is 2.0%,the conversion of CO by 2.0%Au/HZSM-5 is 81.01%,and the selectivity of methyl formate and methyl acetate is 62.12%.The conversion of CO on 0.4%Na-2.0%Au/HZSM-5 catalyst is 88.51%,and the selectivity of methyl formate and methyl acetate is 68.56%.The weakening of strong acid center and medium acid center by Na ion modification increases CO conversion and the selectivity of target product in the carbonylation of syngas reaction.