M.a. Yousefpour, F. Safari Kooshali, B. Khoshandam,
Volume 34, Issue 3 (12-2015)
The purpose of this work was to study the hydrogen adsorption on the surface of mesoporous materials based on silica (SBA-16) modified with palladium via temperature. Since mesoporous silica materials have a high specific surface area, and the ordered mesoporous size of 2-10nm, they are suitable for adsorption and storage of hydrogen. SBA-16 is suitable for this purpose due to its cubic crystalstructure and open pores. Single-stage sol-gel method was used to produce nanostructure composite from salt of palladium (PdCl3) and mesoporous silica precursor. The aging time was selected as 12 hr at 80˚C. Furthermore, the obtained materials were heated at 550˚C for 6 hr to remove surfactant and to form pores. Then the materials were characterized by large angle and small angle x-ray diffraction analysis, and hydrogen absorption analysis at upto 200kPa pressure at three different temperatures of -196˚C (77 K), -123˚C (150 K) and 30˚C (303 K). Furthermore, adsorption-desorption of nitrogen gas was studied. The surface morphology was observed by field emission scanning electron microscope (FESEM). In addition, the amount of palladium, oxygen, and silicon were measured by using energy dispersive spectroscopy) EDS ). Finally, the functional groups on the surface of mesoporous silica materials were evaluated using Fourier transform infrared spectroscopy (FTIR). The results of XRD and EDS analyses confirmed the presence of palladium and palladium oxide in mesoporous amorphous silica. In addition, BET results showed that addition of palladium in SBA-16 decreased the surface area, and produced 791 and 538m2/g for SBA-16 and SBA-16/Pd, respectively. Hydrogen absorption in nano structure composite was decreasing with temperatur in comparison with SAB-16. On the other hand, the maximum hydrogen absorption in the nano structure composite containing palladium was obtained at -196˚C (77 K).
