Enhanced H2 generation from NaBH4 hydrolysis and methanolysis by cellulose micro-fibrous cottons as metal templated catalyst

Abstract

A simple, fast, economic and environmental friendly method has been developed for the preparation of high active metal nanoparticles (MNPs) in the cellulose microfibers of cotton (CFC). The CFCs are kept in aqueous solutions of metal salts to adsorb metal ions. The CFC templated with metal ions are then treated with aqueous solution of NaBH4 for the reduction of metal ions into nano zero-valent metal nanoparticles (nZV-MNPs). The CFC loaded with nZV-MNPs are characterized by XRD, XPS, ATR-FTIR and FE-SEM, which indicates the successful synthesis of nZV-MNPs over the surface of CFC (M@CFC). The M@CFC are utilized as an efficient catalyst for the hydrogen generation from the methanolysis/hydrolysis of NaBH4. The Cu@CFC showed better catalytic performance for the hydrolysis of NaBH4, whereas Ag@CFC catalytic performance were much better than the other loaded MNPs for the methanolysis reaction of NaBH4. Effects of different parameters, which affecting the H2 generation, like type of MNPs, amount of the catalyst, amount of NaBH4, temperature and addition of chitosan (CH) polymer are also investigated. A very low activation energy (Ea), approximately 20.11 ± 0.12 kJ mol−1 for methanolysis reaction of NaBH4 is calculated at temperature range 22–40 °C. Besides, a very high H2 generation obtained in presence of 10, 50, or 100 μL CH solution (2 wt% CH in 20% v/v aqueous acetic acid) in addition to 50 mg of Ag@CFC catalyst at 22 °C and 1000 rpm. Moreover, the reusability of the catalyst is performed and found no decrease in percent conversion, whereas percent activity decreases 35% after four cycles.