Evaluation of V2O5-WO3-TiO2 and alternative SCR catalysts in the abatementof VOCs

Two different commercial SCR catalysts belonging to the V2O5-WO3-TiO2 syste m, and different alternative catalysts based on Mn, Fe, Cr, Al and Ti oxide s have been tested in the conversion of VOCs in excess oxygen in a temperat ure range typical of the SCR process (500-700 K). Propane, propene, isoprop anol, acetone, 2-chloropropane and 1,2-dichlorobenzene have been fed with e xcess oxygen and helium. The industrial catalysts are poorly active in the conversion of propane, giving mainly rise to propene by oxy-dehydrogenation . The conversion of propene is higher with CO as the predominant product. I n any case, the oxidation activity depends on the vanadium content of the c atalyst. Isopropanol is mainly converted into acetone and propene, while ac etone is burnt predominantly to CO. Mn- and Fe- containing systems are defi nitely more active in the conversion of hydrocarbons and oxygenates, giving rise almost exclusively to CO2. 2-Chloropropane is selectively dehydrochlo rinated to propene and HCl starting from 350 K, propene being later burnt t o CO on the industrial V2O5-WO3-TiO2 catalysts, whose combustion activity i s, apparently, not affected by chlorine. On the contrary, chlorine strongly affects the behavior of Mn-based catalysts, that are active in the dehydro chlorination of 2-chloropropane, but are simultaneously deactivated with re spect to their combustion catalytic activity. The conversion of 1,2-dichlor obenzene gives rise to important amounts of heavy products in our experimen tal conditions with relatively high reactant concentration. (C) 1999 Elsevi er Science B.V. All rights reserved.