Sulfidation performance of unsupported and SBA 15-supported Ca-based mixed metal oxides

Abstract

Coal is the most widely used fossil fuel resource, and clean coal technologies allow an increase in the efficiency of clean energy production. Gasification-based combined cycle power generation systems, for example, aim to produce a mixture of CO and H2 (syngas) formed from coal and biomass. However, H2S is an undesired gasification product of fossil fuels with their high sulfur content. Hot gas desulfurization (HGD) reduces the sulfur contents of the gasification products by eliminating thermal losses of endothermic syngas formation processes. This study aims to develop efficient sorbents to remove H2S from hot flue gas. Unsupported and SBA 15-supported Ca-based binary mixed metal oxides (CuO, FeO, MnO, ZnO) were synthesized as sulfur sorbents by the wet impregnation method. The crystal structure of the sorbents was determined by X-ray diffraction (XRD), while BET analysis was used to determine the surface area and pore size distribution of the sorbents. The results of the XRD and BET analyses revealed mixed metal oxide formation and a high surface area of SBA 15-supported sorbents, respectively. Mixed metal oxide formation was also confirmed by Fourier transform infrared radiation (FTIR) spectroscopy. The desulfurization performance of the sorbents was examined by a simulated gas mixture at 800 °C. A gas chromatography analyzer equipped with a flame photometric detector was used to follow the H2S concentration. SBA 15-supported CaO–MnO exhibited the best desulfurization performance at 800 °C with a breakthrough sulfur capacity (BSC) of 43.38 g S/100 g sorbent in the longest breakthrough time of 1077 min.