Thermogravimetric Study of CuO/γ-Al2O3Sorbents for SO2in Simulated Flue Gas

Abstract

A series of CuO/γ-Al2O3 sorbents with different CuO loading prepared by impregnation were characterized using X-ray diffraction (XRD). Temperature-programmed reduction (TPR) was used to study the reducibility of the sorbent. The sulfation activity and sulfation cycles of sorbents were investigated by thermogravimetric techniques, and the change in the pore structure of the sorbent was also studied by Brunauer−Emmett−Teller (BET) methods. It was determined that the monolayer coverage of CuO determined by X-ray quantitative analysis was 0.275 g CuO/(g γ-Al2O3). Below monolayer coverage, CuO was highly dispersed on the γ-Al2O3. Compared to unsupported CuO, microparticles of CuO were reduced easier by H2, but the highly dispersed CuO was difficult to reduce by H2. The optimal CuO loading was 0.12 g CuO/(g γ-Al2O3), far below its monolayer coverage. When CuO loading was equal or more than 0.07 g CuO/(g γ-Al2O3), the sulfated sorbent could be fully reduced by H2. γ-Al2O3 greatly participated in the sulfation, and the negligence of that was reasonable during the reaction between CuO and SO2. Higher temperature could reduce the sulfation time of the copper compound from CuO to CuSO4. The pore structure of the sulfated sorbent could recover to that of the fresh sorbent after regeneration, but long sulfation times could cause an increase in surface area and a decrease in regeneration of the sulfated sorbent.