Carbon spheres as an efficient green catalysts for dehydrogenation of sodium borohydride in methanol

Abstract

Carbon sphere (CS) was successfully synthesized by using starch via hydrothermal process with optimization of all conditions and parameters, systematically. The optimized CS was modified and used as a catalyst in the dehydrogenation of sodium borohydride in methanol for hydrogen production. Factors affecting the H2 production rate such as reaction temperature, catalyst type and amount, NaBH4 amount were investigated. Activation parameters for the dehydrogenation reaction of NaBH4 with the use of amine modified and protonated CS (H-EDA-CS) catalyst were calculated to be 26.14 kJ.mol−1, 23.75 kJ.mol−1, −192.19 J.mol−1.K−1, for Ea, ΔH# and ΔS#, respectively. Maximum HGR value was calculated as 3460 mL.min−1.g−1 at 25 °C. Moreover, reusability studies of the H-EDA-CS catalyst were made and the activity of the catalyst was found to be above 50% even after the 7th use. The catalyst was also regenerated 3 times, and the % activity results for initial use, 1st, 2nd and 3rd regeneration were calculated as 100%, 91%, 80% and 79%, respectively.

Keywords

• Hydrothermal synthesis
• Carbon spheres (CS)
• Green catalyst
• Hydrogen production
• NaBH4 methanolysis