HISTORY AND CONCEPTS OF THE DEVELOPMENT OF METAL COMPLEX AND METAL OXIDE NANOCATALYSTS FOR SOLVING ENVIRONMENTAL PROBLEMS

The article presents the results of many years of research devoted to the development of low-temperature metal complex and metal oxide nanocatalysts for respiratory purposes. This was one of the parts of the general comprehensive project to create modern multifunctional means of protecting the environment and the human respiratory system, which was scientifically substantiated by Professor Alim-Abdul Adimovich Ennan and implemented throughout his life. The work highlights the following issues: general information on the physicochemical justification of methods for purifying air from gaseous toxic substances and requirements for respiratory catalysts; scientific concepts for creating metal complex catalysts of various origins for the oxidation of CO, PH3, SO2 and ozone reduction fixed on carriers; examples of chemical synthesis of metal oxide nanocatalysts and their activity in ozone decomposition reactions and sulfur dioxide oxidation; examples of utilization of nanodispersed particles that are synthesized in the process of welding metals and exhibit catalytic properties in the ozone decomposition reaction; examples of implementation of research results: respirators, installations, publications, dissertation defences, educational process; the scientific school “Metal complex compounds in catalysis” has been created and is operating. The most common toxic gases are SO2, H2S, HF, P2O5, NOx, NH3, SiF4 (1); PH3, AsH3, NO, CO, O3 (2), which are classified by acid-base (1) and redox properties (2). It follows that air purification from the listed substances can be implemented only through a series of sequential stages, namely, trapping of aerodispersed particles; chemisorption absorption of substances classified in group (1); catalytic neutralization of PH3, AsH3, CO, SO2 and O3 in the presence of catalysts fixed on various carriers, which can be metal complex compounds, as well as metal and metal oxide nanocatalysts. The intensive use of catalysis to solve environmental problems has contributed to the formation of a new scientific direction “Environmental Catalysis”, within which theoretical and practical issues of developing effective catalysts for protecting the environment and humans are being addressed. The implementation of this aspect of environmental catalysis is associated with the design of highly effective catalysts for personal respiratory protective equipment (PPE) (gas masks, respirators, autonomous purified air supply systems) that ensure safe and comfortable working conditions. The analysis shows that the range of catalysts for PPE is very limited, which is due not only to the reluctance of companies to invest in the development of new catalysts, but also to specific requirements for such catalysts: ensuring stable air purification from toxic gaseous substances to the MPC and below with constantly changing inlet characteristics of the air flow (qualitative and quantitative composition; temperature; humidity); high catalyst activity with optimal contact time with the purified gas (no more than 0.04 s in a lightweight respirator); simple, cheap and environmentally friendly catalyst preparation technology; catalyst manufacturability in the design of respiratory protective equipment, i. e. being well adaptable to different geometric shapes; small weight and low aerodynamic drag; compliance with sanitary, chemical and toxicological standards applicable to personal protective equipment.