A study of the sulfidation and regeneration reaction cycles of Zn-Ti-based sorbents with different crystal structures

The reaction cycles of the sulfidation and regeneration of Zn-Ti-based sorbents prepared by a physical mixing method (ZT-700 and ZT-1000) or co-precipitation method (ZT-cp) were tested in a fixed bed micro-reactor at middle temperature (Sulfidation; 480 °C, regeneration; 580 °C). The ZnS produced during sulfidation from the Zn₂TiO₄ with a spinel structure (ZT-1000, ZT-cp) was easily regenerated even at 550 °C, while the ZnS produced from the ZnO with a hexagonal structure (ZT-700) needed a temperature higher than 610 °C. After regeneration, each sorbent was restored to its original crystal structure. The differences in the regeneration properties and the reaction cycles of the sorbents were related to the original crystal structures rather than to the physical properties such as pore volume and surface area. To study these differences further, FT-IR, FT-Raman, XRD and TPR were used, and their results including the reaction cycles of the sulfidation and regeneration on the Zn-Ti based sorbents with different crystal structures were discussed.