V_2O_5在硅胶表面的分散及助剂K_2SO_4作用的研究

STUDY ON DISPERSION OF V_2O_5 ON SURFACE OF SiO_2 AND THE EFFECT OF PROMOTER K_2SO_4

用原位XRD方法证明V_2O_5能在硅胶表面自发分散,但所需温度较高.水汽对V_2O_6的分散有一定的阻碍作用.K_2SO_4可显著加快V_2O_5在SiO_2表面的分散速度,并能降低V_2O_5/SiO_2的表面酸性.被中和的主要是强酸位.这可能是K_2SO_4能够改善V_2O_5/SiO_2催化剂在选择氧化反应中选择性的重要原因之一.

It has been shown by in situ XRD that V_2O_5 can disperse spontaneously ontothe surface of silica gel,but the dispersion temperature is relatively high.The presence of H_2O vapour inhibits the dispersion of V_2O_5 to a certain extent,Thedispersion process of V_2O_5 onto the surface of silica gel can be accelerated by usingK_2SO_4 as an additive.The surface acidity of V_2O_5/SiO_2 is quite strong.However,K_2SO_4 can suppress the acidity by neutralizing strong acid sites.This may be oneof the important reasons why K_2SO_4 can improve the selectivity of V_2O_5/SiO_2 formany selective oxidations.