Comparative theoretical study of H2Se adsorption and dissociation on ZnO(10(1)over-bar0), TiO2(110), and Zn2TiO4(010)

Removal of corrosive or toxic species such as As, Se, and S is critical to the successful implementation of high efficiency integrated gasification combined cycle processes to utilize coal as a more environmentally friendly fuel. In this work we comparatively study the mechanisms of surface reaction of H2Se on a regenerable sorbent, zinc orthotitanate (Zn2TiO4), and two constituent materials, ZnO and TiO2, using first-principles density-functional theory. H2Se adsorbs more strongly on the ZnO (10 (1) over bar0) and Zn2TiO4 (010) surfaces than on the TiO2 (110) surface. Investigation of the dissociation rates shows that dehydrogenation should be facile on both Zn2TiO4 and ZnO while it is much slower on TiO2. Evaluation of sublimation energies of Zn2TiO4 and ZnO suggests that Zn2TiO4 has higher thermal stability than ZnO due to addition of TiO2, in agreement with experimental results.