Stability of the Ni–TiO2@nano CaO/Al2O3 complex catalyst used in ReSER process for hydrogen production

• TiO2 coating on the nano CaCO3 as the precursor of nano CaO was prepared.
• The nano CaCO3 with TiO2 coating used to prepare a sorption complex catalyst.
• TiO2 inhibited growth of Ni crystal and prevented formation of (CaO)12(Al2O3)7.
• Complex catalyst increases the stability in ReSER process for hydrogen produce.

This paper describes the preparation and evaluation of a sorption complex catalyst of Ni–TiO2@nano CaO/Al2O3 for hydrogen production by a reactive sorption-enhanced reforming (ReSER) process. TiO2 coating-modified nano CaCO3 as the precursor of nano CaO was prepared by an adsorption phase technique which was able to strictly control the thickness and structure of surface to improve its durability. Ni–TiO2@nano CaO/Al2O3 was prepared by a mixing method which is general mixing that cannot control the content and structure of catalyst. The microstructure was tested by SEM and XRD, and variation in the sorption property of the catalyst was tested by thermogravimetric analysis (TGA). The results showed that TiO2 coating enhanced the stability of the sorption capacity of the catalyst. X-ray diffraction analysis revealed that the TiO2 coating modification inhibited the growth of Ni crystals and prevented CaO and Al2O3 from forming (CaO)12(Al2O3)7 due to the physical isolation by the TiO2 coating of the nano CaCO3. Evaluation of the modified complex catalyst in the ReSER hydrogen production process revealed significant stability for 13 circulations.