Glycerol steam reforming over hydrothermal synthetic Ni-Ca/attapulgite for green hydrogen generation

[Display omitted] •Glycerol steam reforming over hydrothermal synthetic Ni-Ca/ATP was firstly studied.•Effect of Ca content and preparation method on Ni/ATP structure was investigated.•Hydrothermal synthesis (hs) enhanced the distribution of Ca and Ni species over ATP.•Ni-6Ca/ATP-hs had strong CO2 adsorption and abundant Ni-CaOx interfaces.•Ni-6Ca/ATP-hs exhibited superior performance and sinter/coke durability for GSR. Glycerol steam reforming (GSR) is one of the promising technologies that can realize renewable hydrogen production and efficient utilization of crude glycerol. To illuminate the functions of Ca content (3%, 6%, 9%, and 12%, by mass) and preparation method for Ni/ATP catalyst structure and its catalytic behaviors, the Ni-xCa/ATP (x = 3%, 6%, 9%, and 12%, by mass) catalysts are prepared by co-impregnation (ci) and hydrothermal synthesis (hs) method and then tested in GSR. Characterization results of XRD, N2 adsorption–desorption, H2-TPR, HRTEM, XPS, and NH3/CO2-TPD demonstrate that the combined effect between appropriate Ca additive (6%, by mass) and hs enhance catalyst reducibility, uniform distribution of Ca additive and nickel species over ATP, and adsorption for CO2. This attributes to hs method protects the ATP framework through suppressing the interaction of Ca with ATP and promotes the formation of Ni-CaOx interface sites. Therefore, Ni-6Ca/ATP-hs exhibits the highest conversion (86.77%) of glycerol to gas product and H2 yield (76.17%) and selectivity (58.56%) during GSR. Furthermore, XRD, HRTEM, TG-DTG and Raman analyses confirm that Ni-6Ca/ATP-hs also reveals outstanding anti-sintering and coke resistance. In addition, the structural evolution process of Ni/ATP catalyst with Ca introduction and hs method is presented. Considering the high performance, simple preparation process and low cost, the as-prepared catalyst providing new opportunities for utilization of glycerol derived from biodiesel industry.