Sorptive catalyst for the sorptive and oxidative cleaning of exhaust

Abstract

The invention relates to a sorption catalytic converter for the combined chemo-sorptive and oxidative cleaning of diesel engine exhaust gases with a high blocking activity for highly volatile organic exhaust gas components, compounds sorbed on particles, moderately and scarcely volatile organic compounds (SOF), materials with a pungent odor, irritating materials, and ammonia, using an upstream NO.sub.x reducing catalytic converter, with measurable blocking activity for minute high carbon particles, with a high oxidation activity for CO and a restricted oxidation activity for NO and SO.sub.2 with a working range from the ambient temperature to 650.degree. C., comprising a monolithic honeycomb structure having channels adapted for free flow of diesel exhaust gas therethrough of the active mass or of inert carrier material, coated with the active mass, the active mass preferably being composed of V.sub.2 O.sub.5 /WO.sub.3 /MoO.sub.3 mixed oxides borne on sulfatized titanium dioxide, same being doped with platinum metal oxides at a concentration very low in comparison with oxidation catalytic converters, for increasing sorption and oxidation activity. The active mass is employed with 250-1400 g/1 coating composition, whereas for oxidation catalytic converters 50-200 g/1 of coating composition is typical. The significant inhibition of oxidation activity as compared with SO.sub.2 and NO results from a dilution effect (low level of platinum metal; high active mass) and a possible multi-layer structure with a platinum-free or platinum-depleted covering layer. The enhancement of the sorption and oxidation activity is rendered possible by the employment of covering layers with a high pore volume on a honeycomb structure consisting of an active mass whose pore volume is moderately high for reasons of mechanical strength.