“Catalytic” Nox reduction over promoted carbons

摘要

Results on the role of CO as a reducing agent and the effects of a metal catalyst (potassium) are reported for a resin char andrna Wyodak coal char, as well as demineralized samples of the latter. It is shown that “catalytic” enhancement of NO reductionrnby carbon is accompanied by a lower apparent activation energy and greater CO2 production. Additional CO in the gas phasern“catalyzes” NO reduction via the creation of more labile surface complexes and facilitation of desorption of other oxygenrncomplexes. This effect decreases with increasing temperature, and disappears by about 850℃. The apparent activationrnenergy of this reaction is comparable to that induced by the metal catalyst.rnN2O reduction on the potassium-promoted resin char exhibits a lower apparent activation energy than NO reduction over thernsame materials, and produces primarily CO2. Additional CO increases CO2 evolution considerably, while not having anyrndiscernible effect on the N2O reduction rate for the phenolic resin char, but does have an effect for the promotedrndemineralized Wyodak coal char. Mechanistic interpretations of the observed behavior are presented.