Potassium-Promoted γ-Alumina Adsorbent from K2CO3 Coagulated Alumina Sol for Warm Gas Carbon Dioxide Separation

Abstract

This paper provided a practical synthesis method of K-promoted γ-alumina for CO2 precombustion capture integrating adsorbent pelletting and catalytic active component promotion into one single process. The precursor of the absorbent, K-promoted pseudo-boehmite (PB), was synthesized from alumina sol and K2CO3 powder by mixing, aggregating, drying, and aging. Potassium-promoted γ-alumina was obtained after calcination at 400 °C from K-promoted PB. Characteristic crystallines of several stages of products in the synthesis process have been detected by X-ray diffraction. The optimal Al:K ratio in view of CO2 capacity and cyclic performance of K-promoted γ-alumina was obtained by a thermal gravimetric analyzer. The optimal ratio of K-promoted γ-alumina showed a capacity of 0.67 mmol/g (dry base) for the first cycle and 0.34 mmol/g (wet base) after 30 pressure swing adsorption (PSA) cycles at 300 °C. K-promoted γ-alumina adsorbent could be favorable for a low energy penalty precombustion CO2 capture application. It showed a variety of advantages such as low adsorption heat, good mechanical strength, low cost in synthesis, and fair stable capacity.