MCM-41负载钨磷杂多酸催化剂的性能研究

制备并表征MCM-41负载H~3PW~1~2O~4~0(PW)催化剂.PW杂多酸在MCM-41上负载量高达70%(质量分数)时,XRD中仍未检测到其晶相峰.PW杂多酸与MCM-41载体的相互作用要比与SiO~2载体的强.PW杂多酸中的质子位是非常强的酸中心,它们对NH~3的微分吸附热在160-180kJ/mol的范围.与PW杂多酸相比,PW/MCM-41催化剂的酸中心强度变弱并且分布不均匀,其酸量和酸中心分布可以通过改变PW杂多酸的负载量来调节.PW/MCM-41是一类适合于中强酸和弱酸催化反应的新型固体酸催化剂。

12-tungstophosphoric heteropolyacid supported on MCM-41 as acid catalyst

MCM -41 supported H3PW12O40(PW) catalysts were prepared and characterized. PW crystal phase was not observed in X - ray diffraction patterns at PW loading as high as 70% (quality fraction). The chemical interaction between PW and the support was stronger on MCM - 41 than on amorphous SiO2. The acid sites in bulk PW were uniform and strong with differential heat of NH3 adsorption in the range of 160 ~ 180 kJ/mol, whereas in PW/MCM - 41 catalysts the acid sites became less uniform and weaker due to the strong interaction between PW and the support. The quantity and distribution of acid sites in PW/MCM - 41 catalysts could be adjusted by varying PW loading. The catalytic activities of PW/MCM - 41 catalysts toward acid - catalyzed reaction requiring different acid strengths were tested, and the results showed that they were promising catalysts for medium strong and weak acid - catalyzed reactions.