Current Trends in the Application of Monolithic Catalysts in Environmentally Friendly Technologies for Autonomous Heat Supply and Post Combustion Emission Control: A Mini Review

Several approaches aimed at the development of catalytic packages based on ceramic and metal monolithic materials are reported and discussed in this paper. These approaches are intended for heat-generating devices and exhaust gas purification systems where high efficiency and environmental reliability are required with a wide range of concentrations and chemical natures of ecotoxicants, and where the inlet flows are characterized by high volumetric velocities. In particular, the development of an efficient solution-combustion synthesis (SCS) providing more stable and active catalytic coatings on monolith walls is discussed. For effective and environmentally clean local heat supply, a technological solution is proposed involving two-stage combustion of gaseous fuel. At the first stage, the fuel is burned in a flame under oxygen-deficient conditions to suppress the formation of toxic nitrogen oxides. At the second stage, the combustion products are diluted with air, and the resulting hot gas is purified from combustible pollutants on honeycomb-structured ceramic catalysts. Such devices are used for heating greenhouses, cowsheds, residential buildings under construction, and various industrial facilities. Industrial monoliths have a limited diameter, typically not exceeding 300÷500 mm. This is the main limiting factor in the application of catalytic technologies based on monolith materials for the purification of exhaust gases from high-power internal combustion engines. For the purification of the exhaust gas from a stationary diesel power station of 2,000 kW power with a nominal exhaust flow rate of 30,000 Nm3/h, monolithic catalysts and a modular catalytic reactor comprising several monoliths of a large size have been developed.