氧化铝载体在草酸酯合成催化剂中的应用

Application of alumina carrier in catalyst for synthesis of oxalate

介绍硝酸法制备氧化铝载体及其前驱体拟薄水铝石的影响因素,成胶温度、老化温度、老化介质、反应体系pH值等制备条件影响拟薄水铝石孔结构及比表面积。成胶温度和老化温度越高,老化时间越长,老化介质中加入碳酸氢铵等有利于提高拟薄水铝石结晶度,pH值主要影响拟薄水铝石晶形。拟薄水铝石制备过程中、成型过程中及成型后可通过添加助剂、扩孔剂、模板剂,采用水热处理和改变焙烧温度等方法调控氧化铝孔结构和比表面积。氧化铝载体的比表面积和孔结构影响草酸酯合成催化剂的活性和选择性。

The factors affecting the preparation of alumina carrier and its precursor pseudo-boehmite by nitric acid method were introduced.It was found that the pore structure and specific surface area of pseudo- boehmite were affected by the gelation temperature,aging temperature,aging medium,and pH value of reaction system.Higher gelation and aging temperature,longer aging time and adding ammonium bicarbonate in aging medium resulted in higher crystallinity of pseudo-boehmite.pH value mainly affected morphology of pseudo-boehmite.Moreover,the pore structure and specific surface area of alumina could be controlled by adding auxiliaries,pore-enlarging agents,templating agents,and using hydrothermal treatment and calcination temperature adjustment in the processes of preparation,molding,and after molding.Activity and selectivity of catalyst for oxalate synthesis affected by specific area and pore structure of alumina carrier.