Effects of support pore size on new Cs_(2.5)H_(0.5)PW_(12)O_(40)/SiO_2 catalysts for the ring-opening polymerization of tetrahydrofuran

Mesoporous silica supported CS2.5Ho.sPWI2040 catalysts were prepared by impregnation method, and several silica supports with different pore size were utilized. N2 adsorption, XRD and ICP-AES techniques were utilized to characterize the silica supports and catalysts. XRD results showed that the dispersion of Cs2.5Ho.5PW12 was better for the silica support with larger pore size. The catalytic activity results showed that the pore size played important role on the catalyst activity and the molecular weight of PTHF.When CS2.5Ho.5PW12040 was dispersed on larger pore size silica support, the catalysts showed good performances for the synthesis of PTHE The molecular weight of PTHF product on the sample in which Cs2.5Ho.5PW12040 was dispersed on larger pore support was higher than that on the catalyst with smaller pore support. The leaching amounts of the active components for the supported Cs2.5Ho.5PW12040 catalysts were much lower. After five reaction cycles, there were still good activities and stabilities for the supported CS2.5Ho.5PW12040 catalysts with larger pore silica supports. These results were much better than those of the supportedheteropolyacid H3PWI2040 catalyst.