Fe-Based Sorbent for Hot Coal Gas under Microwave Irradiation: Desulfurization Performance and Microwave Effects

The microwave-assisted chemical process is environmentally friendly and energy-saving. In this study, microwave irradiation was applied to enhance the hot coal gas desulfurization process with modified semi-coke-supported Fe 2 O 3 as the sorbent. The results indicate that the sorbent with 20% Fe 2 O 3 shows the greatest breakthrough sulfur capacity (9.0%) at 500 °C in the simulated coal gas. Besides Fe 1– x S, sulfur was also produced during the desulfurization process. The deactivation model could be used to simulate the adsorption behavior of the sorbents for H 2 S. The activation energies of the sulfidation reaction by microwave and conventional techniques are 26.9 and 27.8 kJ mol –1, respectively. The sorbents adsorbing H 2 S under microwave irradiation show much larger initial rate constants (308–2071 m 3 min –1 kg –1 ) for the sulfidation reaction. In comparison to the conventional technique, microwave desulfurization generally results in much better performance of H 2 S removal and leads to less negative effects on the pore structure of the sorbent. The improvement of desulfurization properties may be attributed to the roles of microwave irradiation (enhanced mass transfer kinetics and intensified ion diffusions). Additionally, the adverse influence of H 2, CO, and CO 2 on the sulfur capacity of the sorbents under microwave irradiation is not significant when the adsorption time varies from 0 to 120 min.