Hydrogen generation from chemical looping reforming of glycerol by Ce-doped nickel phyllosilicate nanotube oxygen carriers

This paper describes the synthesis of a series of xCeNi-PSNT (phyllosilicate nanotube) oxygen carriers (OCs) and presents the effect of Ce loading on the performance in chemical looping reforming (CLR) of glycerol. Various characterization techniques including N-2 adsorption-desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), H-2 temperature-programmed reduction (TPR), X-ray photoelectron spectra (XPS) and O-2 volumetric chemisorption were employed to investigate the physicochemical properties of the fresh and used OCs. The characterization results demonstrated that the PSNT structure possessed strong confinement effect and that the Ce promotion improved Ni dispersion and the reducibility of NiO particle and isolated Ni ions. The enhanced reducibility significantly shortened the dead time in the fuel feed step, resulting in the high H-2 generation efficiency. The reactivity and stability tests were conducted in a fixed-bed reactor. A Ce/Ni mass ratio of 0.5 was optimized for CLR with an average H-2 yield of 12.5 wt%, an average NiO conversion of 67%, and an accumulated coke deposition of 3.8 wt% in a 10-cycle stability test. The confinement effect of PSNT and Ce promotion both have positive effects on attaining the excellent performance.