Effect of nickel over the H2 adsorption on Ni/MCM-41 materials

Abstract

Repeated efforts have been made to introduce alternatives to petroleum. One of these alternatives is hydrogen, as it might be a clean and renewable energy vector. Ordered nanostructured materials such as MCM-41 mesoporous molecular sieves have been studied as promising candidates for hydrogen storage. There are several literature reports that concern the nickel loading on porous materials, which indicated that the hydrogen adsorption is maximum at a low metal content and it then decreases with increasing nickel loading on the support [1,2]. However, further investigations are necessary for a deeper understanding of the mechanism of hydrogen adsorption on nanoporous materials. Therefore, in the present work the hydrogen storage capacity of Ni/MCM-41 materials was studied by means of experimental results and Density Functional Theory (DFT) calculations. The Ni/MCM-41 samples were reduced in order to analyze the metallic nickel contribution on the H2 adsorption. Also, hydrogen adsorption isotherms at room temperature and high pressures for reduced and un-reduced samples were measured. The physicochemical properties of the samples, obtained by means of the characterizations performed (TPR, DRX, N2 adsorption-desorption) were correlated with the information provided by the DFT calculations and used to interpret the behavior of the samples in hydrogen storage.