HETEROGENIZATION OF HETEROPOLYACIDS - A GENERAL DISCUSSION ON THE PREPARATION OF SUPPORTED ACID CATALYSTS

Heteropolyacids (HPAs) possess both acidic and redox catalytic propert ies and held extensive promise of practical application. These type of compound display a great potential of specific synthesis reactions fo r replacing sulfuric acid to satisfy the requirements of environmental protection. Heterogenizing HPAs would not only make them more useful in liquid phase oxidation with oxygen and in acid-catalyzed reaction, as the catalyst is often difficult to separate from the reaction produ cts, but also create favorable factors for realizing heterogenization of homogeneous reaction and even utilizing new technology of catalytic distillation. In this paper, different kinds of porous materials whic h are well characterized, including oxides such as Al2O3, SiO2, TiO2, diatomite, bentonite, and active carbon of different sources, were use d as support for heterogenizing HPAs (in different media), and the obt ained results, the intrinsic characters of supports which may influenc e both the nature of the interaction between HPAs and supports in the heterogenization and the activity in the catalytic reaction, are explo red. It is expected that these can provide a referential model for pre paring supported acid catalyst used in liquid phase.