Stability of complex catalyst with NiO@TiO2 core-shell structure for hydrogen production

Abstract

Core-shell NiO@TiO2 and CaO complex catalyst was prepared to improve stability used in the reactive sorption-enhanced reforming (ReSER) process for hydrogen production. NiO@TiO2 as catalyst component was prepared by synthesizing Ni(OH)2 as core via urea hydrolysis, by coating TiO2 shell via adsorption phase reaction technique, and was mixed with nano CaO as CO2 adsorbent to form a complex catalyst. The morphology of NiO@TiO2 and the complex catalyst were characterized by means of TEM, EDS, XRD and N2 physisorption measurements. Hydrogen production performance was investigated in a fixed-bed stainless steel reactor. Results showed that the complex catalyst with core-shell NiO@TiO2 structure has 36 cyclic runs of the ReSER process for hydrogen production, while only nine cycle runs obtained without TiO2 coated as shell. It was revealed that core-shell NiO@TiO2 structure could increase the surface area of complex catalyst and promote the separation of NiO core particles. It was also found that the optimum TiO2 coating time could obtain relative smaller NiO grain. And smaller initial NiO grain in core-shell structure would improve the stability of the complex catalyst.