Effects of different clay-based catalysts on hydrogen production in a sodium boron hydride hydrogen production system

In this study, Co-B, Co-Fe-B and Co-Mg-B catalysts were synthesized by chemical reduction on sepiolite and montmorillonite clays modified with different acids as support material and their activities were performed by obtaining hydrogen from the hydrolysis reaction of sodium borohydride. Acetic acid, hydrochloric acid, boric acid and phosphoric acid were used for the modification of sepiolite and montmorillonite clays. At the same time, optimum acid concentration and optimum impregnation times were determined for the optimization of clay samples. In the hydrogen production experiments, the metal content, sodium borohydride concentration and temperature parameters were examined. Although the interaction of acids with both support materials is different, the most suitable hydrogen production rates are obtained with phosphoric acid. At the same time, significant increases in maximum hydrogen production were detected by addition of Mg or Fe beside Co on the support material. The supported catalyst samples obtained as a result of the processes performed were characterized and interpreted by X-ray diffraction spectroscopy (XRD), scanning electron microscope, infrared spectroscopy and BET surface area device. Characterization studies showed significant changes in the surface of the supported catalysts. On some selected catalysts, hydrolysis was carried out at 30, 40, 50 and 60 ° C to obtain kinetic data. Activation energies of hydrogen production were calculated from hydrolysis of sodium borohydride using clay supported catalysts. The activation energies obtained with montmorillonite-supported Co-B, Co-Fe-B and Co-Mg-B catalysts were found as 49.5, 38.90 and 52.3 kJ / mol, respectively. At the same time, the activation energies obtained with sepiolite-supported Co-B, Co-Fe-B and Co-Mg-B catalysts were found to be 21.4, 43.83 and 38.21 kJ / mol, respectively. Keywords: Co-B, Co-Fe-B. Co-Mg-B, support material, hydrogen, modification