Geopolymer based catalysts—New group of catalytic materials

Abstract

New type of redox heterogeneous catalysts based on geopolymer aluminosilicate materials was developed and their catalytic properties have been demonstrated on industrially important reactions. Geopolymers can be regarded as amorphous analogues of zeolitic materials (three dimensional network of SiO 4 and AlO 4 tetrahedra with negative charge of the network balanced by extra-framework cations, variability in chemical composition, ion exchange properties, presence of rings forming cationic sites for bare cations), but possessing some advantages as network formation at ambient or low temperatures, mesoporosity and low cost preparation. It is shown that the geopolymer network enables incorporation of transition metal ions as active centres for catalytic reactions. The catalytic activity of geopolymer-based catalysts with Fe, Co and Cu metal ions in extra-network sites and Pt species is demonstrated on the selective catalytic reduction of nitrogen oxides by ammonia and the total oxidation of volatile hydrocarbons. These findings open a potential for synthesis of new types of robust catalysts for heterogeneously catalysed reactions.