CONCEPTUAL APPROACHES TO THE DEVELOPMENT OF CATALYSTS FOR LOW-TEMPERATURE CARBON MONOXIDE OXIDATION WITH AIR OXYGEN

Abstract

Actual questions concerning the modern stage of development of catalysts for low-temperature carbon monoxide oxidation and their application in the personal respiratory protective equipment (PRPE) have been analyzed. Some approaches contributing to purposeful control of activity of Wacker type catalysts consisting of both palladium(II) and copper(II) salts and sorbents of different origin as well as their possible use in several environment protection devices have been considered. Despite some progress in the development of new catalysts for low-temperature CO oxidation, Hopcalite catalysts characterized by well-known disadvantages are as usual used in the series-produced PRPE. In our opinion, Au containing nanocatalysts and Pd(II)-Cu(II) catalysts based on modified natural sorbents such as Tripoli and clinoptilolite (Ukraine) are more perspective for this purpose. Available data concerning test conditions and activity parameters for some commercial catalysts at comparable CO inlet concentrations commonly used in PRPE, i.e. 130-300 mg/m3, were summarized. For comparison of their activity and evaluation of their applicability in PRPE, their air purifying ability (down to MPCCO in the air of work area) was used. It can be seen that the Au containing Nanoqold Cat (0.57 % Au/TiO2/AC) nanocatalyst demonstrates the highest activity providing the almost complete air purifying from CO: at CO inlet concentration of 625 mg/m3 and the residence time value of 0.04 s, the outlet concentrations are 1.25‑7.5 mg/m3 for 12 h. For NanAuCat (0.57 % Au/TiO2/AC) and AUROlite (1 % Au/TiO2), CO conversion values were equal to 48 % and 22 %, respectively, however, in this case the residence time value was lower by an order of magnitude. STC catalyst (Pt/SnO2) and AK-62 (2.4 % Pd/Al2O3) catalyst are less active than the above mentioned Au containing catalysts. The Wacker type catalysts are characterized by similar parameters however KNO-CO/MT is somewhat better showing the air purification down to MPC even at the residence time of 0.29 s. The residence time is a parameter determining the catalyst weight necessary to achieve a required CO conversion and dimensions of an applicable gas mask filter. Hopcalite catalysts used in the PRPE produced by the main companies over the world are the cause of large dimensions and weights of PRPE cartridges and canisters. Thus, low values of catalyst weights in “Platan” and “Suprovidnyk” devices, i.e. 50 g and 97 g, respectively, and high levels of protection from CO are their great advantages.

Keywords

• монооксид карбону
• низькотемпературне окиснення киснем повітря
• каталізатори
• засоби індивідуального захисту органів дихання