Ni-embedded TiO2-ZnTiO3 reducible perovskite composite with synergistic effect of metal/support towards enhanced H2 production via phenol steam reforming

Abstract

4Highly reducible Ni-dispersed TiO2-ZnTiO3 perovskite nanocomposite with different anatase/rutile contents of TiO2 for enhanced phenol steam reforming (PSR) towards selective H2 production has been investigated. In-situ growth of TiO2 nanoparticles (NPs) over ZnTiO3 cubic perovskite was obtained through hydrothermal assisted impregnation method. TiO2-ZnTiO3 composite performance was entirely dependent on the Zn/Ti molar ratios. With Zn/Ti molar ratio of 2, 19.80% TiO2 rutile phase in TiO2-ZnTiO3 composite was obtained, giving highest catalytic activity for H2 production. Using 10% Ni supported TiO2-ZnTiO3, phenol conversion and H2 yield of 89.10% and 75.60%, respectively were attained, while it was only 44.60% and 63.32% with 10% Ni/TiO2 NPs. This was obviously due to strong metal-support interaction with higher Ni-dispersion. More importantly, CO yield with Ni/TiO2 was 9.68%, decreased to 6.49% using 10% Ni/TiO2-ZnTiO3 perovskite composite, resulting in lower CO/CO2 ratio and trivial coke formation. Besides, Ni/TiO2-ZnTiO3 composite gave stability for more than 50 h without obvious deactivation, while it was only 6 h over Ni/TiO2 NPs. The effect of operating parameters reveals that reaction temperature 700 °C, catalyst loading 0.3 g and phenol/water ratio 5/95 wt% gave the highest catalyst activity. Besides, activity was also enhanced with increasing GHSV (mL.g−1.h−1), which confirms external mass transfer limitation. In conclusion, strong metal-supports interactions in Ni/TiO2-ZnTiO3 composite provide higher Ni-dispersion for stimulating catalytic activity and can be considered as a promising material for hydrogen production applications.