Sulfation, pore, and fractal properties of hydrated spent calcium magnesium acetate from calcium‐based looping

Abstract

AbstractHydration of the spent calcium‐based sorbent from calcium‐looping can improve its inadequate pore characteristics. The hydrated sorbent can be used for desulfurization before calcium‐based looping, which decreases the SO2 concentration in the flue gas entering the calcium‐based looping and also decreases the cost of CO2 capture. The effects of hydration time, hydration temperature, and liquid‐solid ratio on the reactivation performance of a hydrated spent calcium‐based sorbent were studied using spent calcium magnesium acetate (CMA) in this study. Fractal analysis based on the pore structure data of the hydrated sorbents was also conducted, and the relationship between the fractal dimension and the desulfurization performance of the hydrated spent sorbents was also investigated. The results showed that the sulfation conversion rate of the hydrated spent CMA decreased slowly at first, and then increased with hydration time. The conversion rate also increased with the hydration temperature but it decreased with the liquid‐solid ratio. The maximum sulfation conversion of the hydrated spent CMA under the optimized conditions was 68.0%, which approached that of fresh CMA. Compared to that of spent CMA, the sulfation conversion increased by 53.3%. The spent CMA consisted mainly of mesopores and macropores. After hydration, the volumes of both types of pores increased. However, the mesopore percentage decreased, while the macropore percentage increased. The hydrated spent CMA had obvious fractal characteristics. There was an optimum range for the fractal dimension of the samples, 2.31 < D < 2.35, at which the sulfation conversion was maximized. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.