Catalytic Air Heaters

Abstract

bustion, significant amounts of noxious substances are let off into the atmosphere, which produces an adverse effect on the environment. Further, one of the major sources of pollution are nitrogen oxides (NOx) consisting of the monoxide NO, the dioxide NO2, and the hemioxide N2O which are considered highly toxic. The concentration of nitrogen oxides has been going up constantly producing a greenhouse effect and reducing the ozone layer of the earth. Moreover, in the combustion products there is quite a lot of oxides of carbon, sulfur, benzopyrene, and other deleterious substances. Consequently, purification of combustion products from nitrogen and carbon oxides poses a serious technological problem. However, such purification is associated either with catching of gaseous emissions or with their conversion into useful or virtually harmless compounds. The methods employed in the industry for purification of gaseous emissions are based on absorption, adsorption, condensation, separation by a membrane, thermal combustion, chemical conversion of impurities into nontoxic compounds, biochemical purification, and catalysis. At present, catalysis is one of the promising and inexpensive methods of purification of combustion products. Its major advantages vis-a-vis other methods are high efficiency, low cost, and absence of harmful secondary phenomena. Catalytic reactions may be depicted as follows: