Development of CNT-supported Cu, Nb and Fe-based catalysts for hydrogen production from NaBH4 methanolysis

In this study, carbon nanotube (CNT)-supported Cu, Bi, Nb, Fe, CuBi, CuFe, and NbBi catalysts were synthesized with different atomic ratios using the sodium borohydride (NaBH4) reduction method. The catalytic performance of the synthesized catalysts for the recovery of hydrogen stored in hydride via NaBH4 methanolysis was investigated. XRD, SEM-EDX and mapping, XPS, TPR, and TPD analysis techniques were used to characterize the catalysts. Hydrogen production rates of catalysts prepared at different ratios were examined, and optimization studies were conducted for each catalyst with the highest hydrogen production rate. Optimization studies were carried out for NaBH4 amount, methanol amount, catalyst amount, and different temperatures. At a reaction temperature of 30°C, the hydrogen production rates were found to be 7616.28 mL/gcat.min for 3% Nb/CNT, 8900.04 mL/gcat.min for 3% Fe/CNT, 7158.96 mL/gcat.min for 3% Bi/CNT, 7246.08 mL/gcat.min for 3% Cu/CNT, 8954.16 mL/gcat.min for 3% CuFe(50:50)/CNT, 8826.6 mL/gcat.min for 3% NbBi(50:50)/CNT, and 9716.28 mL/gcat.min for 3% CuBi(80:20)/CNT. According to kinetic investigations, activation energies of the methanolysis process were calculated using the Arrhenius equation as 34.72 kJ/mol for 3% CuBi(80:20)/CNT, 14.85 kJ/mol for 3% CuFe(50:50)/CNT, 17.897 kJ/mol for 3% NbBi(50:50)/CNT, and 14.166 kJ/mol for 3% Fe/CNT catalysts.