Temperature dependence of hydrogen adsorption properties of nickel-doped mesoporous silica

The temperature dependence of the hydrogen adsorption properties of nickel-doped mesoporous silica (MCM-41) synthesized by a direct hydrothermal method was investigated by measuring the amount of hydrogen adsorbed at pressures up to 100 kPa at 298, 373, and 473 K. Nickel-doped MCM-41 adsorbed more hydrogen than undoped MCM-41 and metallic nickel at ≈298/0, 373/0, and 473 K/0 kPa due to chemical adsorption enhanced by the highly dispersed nickel particles. Chemical adsorption increased with increasing nickel content and adsorption temperature, suggesting the presence of adsorption sites. The nickel doping also brought the spillover effect, which enhances the physical adsorption of hydrogen. The spillover effect was enhanced at high nickel contents and adsorption temperatures.