Effect of Ni/Al atomic ratio of mesoporous Ni–Al2O3 aerogel catalysts on their catalytic activity for hydrogen production by steam reforming of liquefied natural gas (LNG)

Mesoporous Ni–Al2O3 (XNiAE) aerogel catalysts with different Ni/Al atomic ratio (X) were prepared by a single-step sol-gel method and a subsequent CO2 supercritical drying method. The effect of Ni/Al atomic ratio of mesoporous XNiAE aerogel catalysts on their physicochemical properties and catalytic activity for steam reforming of liquefied natural gas (LNG) was investigated. Textural properties and chemical properties of XNiAE catalysts were strongly influenced by Ni/Al atomic ratio. Nickel species were highly dispersed on the surface of XNiAE catalysts through the formation of surface nickel aluminate phase. In the steam reforming of LNG, both LNG conversion and hydrogen yield showed volcano-shaped curves with respect to Ni/Al atomic ratio. Average nickel diameter of XNiAl catalysts was well correlated with LNG conversion and hydrogen yield over the catalysts. Among the catalysts tested, 0.35NiAE (Ni/Al = 0.35) catalyst with the smallest average nickel diameter showed the best catalytic performance. The highest surface area, the largest pore volume, the largest average pore size, and the highest reducibility of 0.35NiAE catalyst were also partly responsible for its superior catalytic performance.

Research highlights
► Hydrogen was produced by steam reforming of liquefied natural gas (LNG).
► Mesoporous Ni–Al2O3 aerogel catalysts were used.
► Catalytic performance strongly depended on Ni/Al atomic ratio.
► Average nickel diameter played an important role.