ZnO/SBA-15 composites for mid-temperature removal of H2S: Synthesis, performance and regeneration studies

ZnO/SBA-15 composites for mid-temperature H2S removal were prepared by both conventional Incipient Wetness and Two-Solvents impregnation techniques. The composites, differing as to the ZnO loading and the calcination treatment, were characterised by X-ray diffraction, transmission electron microscopy (also in the high resolution mode) and N2 physisorption. Characterisation techniques revealed that zinc oxide was highly dispersed into/over the well-ordered mesoporous channels. In all the composites the mesostructure of the support was still retained together with a high surface area, large pore volume and uniform pore size. The sorbent performance for H2S removal from a H2S/He stream was investigated and compared with a commercial ZnO sorbent. The confinement of the active phase in the SBA-15 structure enhances its ability to interact with hydrogen sulphide, which results in improved performance. Temperature-programmed experiments were carried out for selecting appropriate regeneration conditions. The regenerated sorbent showed a sorption capacity even higher than that of the fresh ones. Such behaviour is maintained in repeated sorption/regeneration cycles.