Effects of second metal oxides on zirconia-stabilized Ca-based sorbent for sorption/catalyst integrated gasification

Abstract

Zirconia-stabilized Ca-based sorbent has been previously investigated for cyclic CO2 capture processes; however, the cost of pure zirconia may be a matter of concern. The cost of sorbent can be decreased by addition of a low cost second metal oxide with zirconia-stabilized Ca-based sorbent. This study examined a number of mixed metal oxides supports, such as alumina, silica, titania, magnesia and molybdena, with zirconia (ZrO2) for stabilization of calcium (Ca) based sorbents directly produced from a co-precipitation method. Selected metal oxide supports (i.e. alumina and silica) are commonly used in catalytic steam gasification.The proposed novel strategy aimed at enhancing sorbent stability, increasing surface area, decreasing cost of zirconia-stabilized sorbents and investigating the effects of the common used supports in catalytic steam gasification on the performance of Ca-based sorbents.The optimal composition for the activity of ceramic-stabilized calcium oxide (CaO) samples under mild operating conditions was determined to be 10wt.% ceramic incorporated in the sorbent. The results indicated considerable sorbent stability and capacity improvement for mixed metal oxide zirconia-stabilized CaO over those of pure CaO, which showed significant cyclic capacity decay under similar conditions. Among the studied materials, aluminum zirconate, calcium zirconate, and zirconium molybdate stabilized sorbents showed the best initial uptake and performances in severe operating conditions over 60 cycles. However, titania, silica and magnesia supports showed negative effect on the sorbent performance.