A new method of chemical immobilization of Keggin heteropolyacids (HPAs) was suggested. H3PW12O40, H4SiW12O40, and H3PMo12O40 were immobilized on the silica which was previously grafted with zirconium butoxide. The immobilization method promoted strong interaction HPA-support and yielded 25 wt.% of well-dispersed HPAs, so increasing the density of acid sites. The catalysts were active in the reaction
提出了一种
化学固定Keggin杂多酸(HPA)的新方法。将H 3 PW 12 O 40,H 4 SiW 12 O 40和H 3 PMo 12 O 40固定在预先用
丁醇锆接枝的
二氧化硅上。固定化方法促进了HPA载体的强相互作用,并产生了25 wt。%的HPA分散均匀,因此增加了酸性位点的密度。该催化剂在
硬脂酸甲酯与
正丁醇的酯交换反应和
油酸与
三羟甲基丙烷的酯化反应中具有活性。我们证明,与固定化的H 3 PMo相反参照图12 O 40,基于H 3 PW 12 O 40和H 4 SiW 12 O 40的催化剂在非极性
油酸介质中对沥滤稳定。根据相互作用强度HPA-support,提出了关于在非极性介质与极性介质中规避浸出的讨论。支撑物与H 3 PW 12 O 40(或H 4 SiW 12 O 40)之间的相互作用更强(即,对浸出的抵抗力更强))是指Zr和W之间的电负性差异较小,而Zr–O–W键与Zr–O–Mo键相比具有较低的极化率。