NOX REDUCTION WITH HYDROCARBONS OVER SOME OXIDE CATALYSTS

A series of copper-gadolinium oxide catalysts supported on thermal resistant carriers have been prepared by impregnation. The degree of NO conversion to N2 in hexane containing atmosphere has been determined over the catalysts at 570-770 K in laboratory and larger-scale experiments. The influence of oxygen and SO2 on the catalyst behaviour has been studied. The results indicate that ca 60-% NO conversion to N2 is attainable at 650-770 K if the purified gas contains initially no more than 10 % O2 and 40 ppm SO2. The gamma-Al2O3-supported catalyst was found to be the most effective one. It was tested in DeNOx process of the exhaust gases from Diesel engine in which NOx reduction of ca 50 % was attained. Its not too high resistance against hindering of NOx reduction by SO2 can be enhanced to some extent, especially if the purified gas contains 50-500 ppm Of SO2, by addition of ammonia molybdates or tungstates to the copper+gadolinium nitrates mixture during the catalyst preparation.