NON-METALLIC HETEROGENEOUS CATALYSTS BASED ON POLYMER CARBON NITRIDE

Abstract

Graphite-type carbon nitride (g-C3N4), which has various and extremely valuable properties, is of great interest because it is a promising material for use in modern technologies. This brief review is devoted to the synthesis and study of non-metallic heterogeneous catalysts based on polymer carbon nitride. The most suitable method for the synthesis of g-C3N4 is the thermal condensation of nitrogen-rich compounds (cyanamide, disianamide, urea, melamine, etc.) at atmospheric pressure. g-C3N4 is resistant to temperatures from 550 to 600°C, insoluble in most organic solvents, and is a semiconductor with a fairly small band gap. This material is of great practical interest due to its prospects for use in electronics, optics, photography, electro- and chemical catalysis. The catalytic activity of g-C3N4 is mainly determined by its structural properties. In order to obtain important catalytic properties in the synthesized carbon nitrides, in recent years new methods have been proposed for their synthesis using various templates and modifiers, which allow to obtain a unique nanostructured and highly porous g-C3N4. In carbon nanomaterials where atoms are in the sp2 hybridization state, two types of active centers are formed that differ in the adsorption resistance of the reagents: weak active chemical sorption centers on the main planes and strong centers on the edges of the main planes on which the adsorbed molecules are transformed. These properties allow the use of g-C3N4 as an effective catalyst without the participation of metals in the practically important processes such as photolysis of water, condensation of the molecule CO2 and benzene to phenol, oxidation of hydrocarbons and selective hydrogenation of alkynes. Research in this area will allow the formation of truly metal-free catalysts in the form in which they occur in nature