Use of Alumina Supported Co-P and Ni-P Catalysts Synthesized By Electroless Plating Method in NaBH4 Hydrolysis

In this study, catalyst synthesis with a long service life and high activity by hydrolysis was aimed at using NaBH4, which is used as a hydrogen storage. Commercial alumina is used as a catalyst support, and Co-P and Ni-P loadings were done using the electroless plating method. The characterization was done using XRD and SEM/EDS analyses. In Co-P catalyst, the ratio of metal/P /P (weight) was determined as 2.5, whilst that of Ni-P was 1.2. Both synthesized catalysts had P and metallic forms as well as metal-P alloy structures. Co-P-based catalysts showed higher activity than Ni-P catalysts in hydrogen production from NaBH4 via hydrolysis. The high Co/P ratio explained high activity in the Co-P/alumina catalyst, and more Pd (9.36% by mass) was detected on the catalyst surface. Regarding Co-P/alumina catalyst, the effects of NaBH4 concentration, NaOH concentration and reaction temperature on the amount of hydrogen produced and the production rate were examined. The hydrogen production rate increased with increasing NaBH4 concentration up to a specific value (0.3 M), after that, no significant change was observed, which is explained by the increase in viscosity caused by the by-product NaBO2, its strong adsorption to the catalyst surface, hence the closure of active centers. NaOH concentration had not significantly affected the hydrogen production amount and rate for the selected operating conditions. As the temperature was increased from 20°C to 60°C, the hydrogen production rate increased approximately three times, and the activation energy was calculated as 25 kJ/mol. In repeat experiments, 74% of the initial performance was preserved after the tenth use.