NOx removal in a rotating packed bed: Oxidation and enhanced absorption process optimization

In view of the continuously stringent standard of nitrogen oxides (NOx) emissions, developing new technologies for NOx removal or updating the existing NOx removal system is very urgent. This work introduces a novel technology for NOx removal in an RPB reactor by the combination of oxidation and enhanced absorption. Experimental results show that a rotating packed bed (RPB) reactor, having high gas-liquid mass transfer efficiency, is a more appropriate choice for NOx removal. Then a series system combining firstly a stirred tank reactor (STR) and secondly an RPB reactor, has been developed in order to oxidize more NO to NO2 that is very soluble and enhances the subsequent absorption in the RPB reactor. The higher oxidation degree (similar to 99%) was achieved with a sodium chlorite concentration of 0.10 mol L-1 and a liquid volume of 5.0 L in the STR. An absorbent containing sulfonated cobalt phthalocyanine (CoPcS) was employed in the RPB reactor to meet the demand of very efficient denitrification for a long-term running. Compared to the traditional urea/sodium chlorite composite absorbent in a single RPB system, the total NOx removal efficiency increased by approximately 30% through the absorbent containing CoPcS in a series system under the optimized conditions.