Lattice substitution and desulfurization kinetic analysis of Zn-based spinel sorbents loading onto porous silicoaluminophosphate zeolites

Abstract

Green Zn-based spinel sorbents for hot coal gas desulfurization have been developed with the assistance of optimization procedures. The pilot study highlights an outstanding ordered mesoporous support (SBET = 323 m2 g−1, Da = 4.3 nm) of SAPO-34@as-prepared SBA-15 (SS) for loading active metal oxides. ZnCo2O4 spinel loaded onto SS (ZnCo2/SS) exhibits a prominent desulfurization performance compared to other sorbents whose partial Co is substituted by Mn or Fe in spinel B-site, owing to the slight effect of PO43− in SS. After systematic evaluation on role of sulfidation condition, 50 wt% ZnCo2/SS sorbent possesses the sulfur storage capacity of 138.08 mg g−1at550 °C and little loss of active species in 5 desulfurization-regeneration cycles. Results of high resolution transmission electron microscopy (HRTEM), Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS) etc. demonstrate that 70.42% of initial sulfur capacity of ZnCo2/SS presented in the 2nd utilization is associated with zinc evaporation, existence of high stable sulfides and partial sintering. The improved deactivation kinetic model suitably describes that the H2S concentration distribution relates with the spatial position of fixed-bed reactor and desulfurization time.