Testing of the CuO/Al₂O₃ catalyst-sorbent in extended operation for the simultaneous removal of NO(x) and SO₂ from flue gases

A series of CuO/Al₂O₃ catalyst-sorbents have been subjected to a large number of reaction-regeneration cycles and their physical and chemical properties compared before and after operation. The reaction phase of the cycle involved exposing the catalyst-sorbents to a mixture of SO₂, NO, NH₃, O₂, and steam at 350 °C, during which time NO conversion was always greater than 90% and the SO₂ was converted into CuSO₄. The regeneration phase involved reduction of CuSO₄ to copper metal by CH₄ at 500 °C, followed by oxidation in air at 450 °C. In some tests the reaction or regeneration conditions were made more severe in an attempt to accelerate deactivation. The SO₂ sorption capacity of one sample, which had been subjected to 1525 cycles, was reduced by about 25%, but generally there was no significant change in reactivity. Small changes in physicochemical properties are interpreted in terms of redispersion of the supported copper phase.