Effect of microwave irradiation on the preparation of iron oxide/arenaceous clay sorbent for hot coal gas desulfurization

For applications in the high temperature coal gas desulfurization process, iron oxide/arenaceous clay sorbents were prepared by microwave irradiation and conventional heating, respectively. The desulfurization performances of sorbents were evaluated using a fixed-bed reactor with simulated coal gas. The effects of calcination temperature and microwave heating time on the properties of sorbents were also investigated. The microwave-irradiated sorbents exhibit sulfur capacity and reactivity greater than those prepared by conventional heating. X-ray diffraction, X-ray photoelectron spectroscopy, a scanning electron microscope, a transmission electron microscope and N2 adsorption were used to characterize the physical and structural properties of the sorbents. Several benefits have been observed using microwave heating rather than conventional heating for the preparation of sorbents. The results indicate that microwave irradiation leads to better inner structure of sorbent and more uniform distribution of the active component with smaller particle size, which facilitate chemical reaction and mass transfer. Microwave irradiation also results in greater outer layer electron density and higher contents of surface metal element, both of which are beneficial to the increase of absorption efficiency and desulfurization reactivity. Then the microwave-irradiated sorbents were tested for three successive sulfurization-regeneration cycles, the 3rd regenerated sorbent still performed well with no apparent deterioration, it proved that the sorbent has good regenerability and is suitable for hot gas desulfurization.