Nitrogen and Oxygen Heteroatom Doping with Hydrothermal Nitric Acid Treatment on the Catalytic Performance of Metal-Free Carbon Particles: Hydrogen Release from Sodium Borohydride in Methanol

Abstract

In this study, the production of two-stage metal-free catalysts from pistachio shells, which are abundant in Turkey and the world, is designed. The first stage of the study includes activated carbon(AC) production, and the second stage includes the production of heteroatom-doped catalysts as a result of hydrothermal heating of the obtained activated carbon with nitric acid. These metal-free catalysts obtained were used for the production of hydrogen (H-2) from sodium borohydride (NaBH4) in methanol. In H-2 production experiments, the NaBH4 concentration effect, temperature effect and catalyst amount effect and catalyst reusability parameters were investigated. HGR values obtained from the methanolysis using metal-free catalysts treated by the nitric acid/water ratio: 1:2, 1:3, 1:4, 1:5 are 8041, 8955, 10600 and 8333 ml min(-1) g(-1), respectively. The activation energy (Ea) of the production of H-2 from NaBH4(NaBH4-H-2-P) in methanol by the metal-free catalyst was 18.19 kJ mol(-1). Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), CHNS elemental analysis, scanning electron microscopy (SEM), and nitrogen adsorption analyses were performed for the characterization of the metal-free catalysts obtained. In addition, the mechanism of the obtained metal-free catalysts on the NaBH4-H-2-P in methanol is discussed.