Three dimensional ordered macroporous zinc ferrite composited silica sorbents with promotional desulfurization and regeneration activity at mid-high temperature

Abstract

A series of 3DOM zinc ferrites and silica composites were prepared and applied on the hydrogen sulfide (H2S) removal at 500 °C. With ∼230 nm-sized macropores and 15 nm-sized walls, the morphology analysis showed the as-prepared ZnFe2O4-SiO2 materials were conducted as a typical 3DOM structure. As a solifidation agent, silica significantly influenced not only the composites structure, which induced the homogeneity and stability of 3DOM structure, but also the desulfurization behavior, in which the active phase utilization decreased if the compounded silica amount was too high or too low. Anyway, the 3DOM sorbents exhibited remarkable desulfurization performance due to the unique structure features with high surface area, nano zinc ferrite particles, well arranged macropores with interconnected mesopores, which significantly enhances gaseous reactant diffusion during sulfidation compared with those of bulk sorbent. Sulfates could be formed during both sulfidation and regeneration process, while Fe2(SO4)3 in sulfided sample and ZnSO4 in regenerated sample. 3DOM structure and silica participation enhanced the breakthrough capacity of 50 wt% ZnFe2O4 compounded sorbent and maintained higher desulfurization capacities upon multiple sulfidation/regeneration cycles more ascribed to its special structural feature.