Investigation of the performance of metal-free catalyst prepared from black tea and green tea waste for hydrogen production via methanolysis of sodium borohydride and optimization using response surface methodology

• Published in: International journal of hydrogen energy 2023-11, Vol.48 (92), p.35919-35937
• Main Authors: Srivastava, Naman, Pal, Neha, Agarwal, Madhu, Dohare, Rajeev Kumar
• Format: Article
• Language: English
• Subjects: Hydrogen; Metal-free catalysts; Methanolysis; Waste tea leaves
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2023.05.356

This study uses a waste biomass-based (green tea leaves and black tea leaves) catalyst for hydrogen production by methanolysis of sodium borohydride (NaBH4) in two ways. The Response Surface Methodology was used for parameter optimization of HGR using AAPC-WGTL and AAPC-WBTL at various parameters such as amounts of catalysts, NaBH4, and reaction temperature. In the case of the AAPC - WBTL catalyst, the highest HGR of 7676 ml min−1 g catalyst−1 was observed at 0.25 g NaBH4, 0.1 g catalyst, and 10 ml methanol (CH3OH) at 50 °C. For the AAPC - WGTL catalyst, the highest HGR of 9084.75 ml min−1g catalyst−1 was observed at 0.15 g NaBH4, 0.1 g catalyst, and 10 ml CH3OH at 50 °C. Moreover, the activation energies were found to be 47.06 kJ/mol and 47.89 kJ/mol for the AAPC-WBTL and AAPC-WGTL catalysts, respectively. FTIR, BET, SEM-EDS, HRTEM and XPS characterized the catalyst. The BET analysis shows that AAPC – WGTL and AAPC-WBTL catalysts have surface areas of 22.96 m2/g and 3.28 m2/g, pore diameters of 1.72 nm and 1.70 nm and pore volumes of 0.0047 cm3/g and 0.0331785 cm3/g respectively. Furthermore, Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) were performed. The AAPC-WGTL and AAPC-WBTL electrode shows 121 mF/cm2 and 63.77 mF/cm2 capacitance, respectively. Therefore, it can be said that WGTL and WBTL are both biomass capable of producing H2 using methanolysis of NaBH4. •The catalysts were synthesized by simple and green procedures for hydrogen generation.•HGR of AAPC-WGTL and AAPC-WBTL was evaluated.•The highest HGR of 9084.75 ml min−1 g catalyst−1 was obtained at optimum conditions using AAPC-WGTL catalyst.•AAPC-WGTL catalyst has shown good reusability.•Good capacitance was achieved in the AAPC-WGTL electrode.