System and process for efficient SCR at high NO2 to NOx ratios

A system for the removal of volatile organic compounds, carbon monoxide and nitrogen oxides from off-gas comprising

• a) a source of ammonia
• b) means for introducing ammonia into a catalytic article having an SCR functionality;
• c) a catalytic article having both an oxidation and an SCR functionality, the catalytic article comprising
• a catalyst substrate and a catalyst composition comprising at least one platinum group metal and/or at least one platinum group metal oxide, at least one oxide of titanium, at least one oxide of vanadium, and 0.001 to 10 wt.-% of at least one oxide of tungsten, calculated as WO3 and based on the total weight of the catalytic article,
• wherein the washcoat is located in and/or on the walls of the catalyst substrate,
• d) means for measuring the amount of NOx and/or the ammonia slip between the outlet end of the catalytic article and a channel through which the off-gas is exhausted or at the channel,
• e) at least one carbon monoxide source, and
• f) means for introducing carbon monoxide into the catalytic article.