活性炭负载磷钨酸催化剂的表征及其催化性能

Characterization and Catalytic Performance of Tungstophosphoric Acid Catalysts Supported on Activated Carbon

研究了活性炭负载磷钨酸催化剂的表征及在丁基多苷合成中的催化性能.活性炭负载磷钨酸催化剂采用浸渍法制备,并用FT-IR光谱、XRD光谱、SEM等手段进行了表征.结果表明,磷钨酸负载到活性炭后保持了原有的Keggin结构,它在载体上的吸附过程可以分为单分子吸附、多分子吸附和体相堆积三个阶段.在丁基多苷合成反应中,催化剂负载量、磷钨酸溶脱量、葡萄糖转化率之间有较复杂的关系.杂多酸溶脱量随负载量增大而增大,转化率与杂多酸溶脱量之间没有直接联系.催化剂负载量在5%到60%之间变化时,控制催化活性的主要因素分别是催化剂酸量、比表面积、游离的杂多酸量.最佳负载量为20%.

The characterization of tungstophosphoric acid（TPA） catalysts supported on activated carbon and catalytic performance in synthesis of butylglycosides were studied. The supported catalysts were prepared by impregnation technique and characterized by FT-IR, XRD and SEM. The characterization results show that the Keggin structure of TPA remains unaltered after being supported on activated carbon. The adsorption process of TPA on activated carbon could be devided into three stages, which are monomolecular adsorption, muhimolecular adsorption and packing of crystalline phase. There are complex relationship with the leaching amount of TPA, the TPA loading amount and the glucose conversion during the butylglycosidation. With the increase of TPA loading amounts the leaching amount of TPA increased, while there＇s no direct relation between the loading amount and the glucose conversion. When TPA loading amount increases from 5% to 60% the key factor controlling the catalytic activaty changes is acidity, specific surface area of the catalysts and amount of the leached TPA respectively. The optimal TPA loading amount on the activated carbon is 20%.