Testing of the CuO/Al2O3 catalyst-sorbent in extended operation for the simultaneous removal of NOx and SO2 from flue gases

A series of CuO/Al2O3 catalyst-sorbents have been subjected to a large numb er of reaction-regeneration cycles and their physical and chemical properti es compared before and after operation. The reaction phase of the cycle inv olved exposing the catalyst-sorbents to a mixture of SO2, NO, NH3, O-2, and steam at 350 degrees C, during which time NO conversion was always greater than 90% and the SO2 was converted into CuSO4. The regeneration phase invo lved reduction of CuSO4 to copper metal by CH4 at 500 degrees C, followed b y oxidation in air at 450 degrees C. In some tests the reaction or regenera tion conditions were made more severe in an attempt to accelerate deactivat ion. The SO2 sorption capacity of one sample, which had been subjected to 1 525 cycles, was reduced by about 25%, but generally there was no significan t change in reactivity. Small changes in physicochemical properties are int erpreted in terms of redispersion of the supported copper phase.