Apricot Kernel shell waste treated with phosphoric acid used as a green, metal-free catalyst for hydrogen generation from hydrolysis of sodium borohydride

Abstract

In this study, grinded apricot kernel shell (GAKS) biobased waste was used for the first time as a cost-effective, efficient, green and metal-free catalyst for hydrogen generation from the hydrolysis reaction of sodium borohydride (NaBH4). For the hydrogen production by NaBH4 hydrolysis reaction, GAKS was treated with various acids (HCl, HNO3, CH3COOH, H3PO4), salt (ZnCl2) and base (KOH). As a result, the phosphoric acid (H3PO4) demonstrated better catalytic activity than other chemical agents. The hydrolysis of NaBH4 with the GAKS-catalyst (GAKScat) was studied depending on different parameters such as acid concentration, furnace burning temperature and time, catalyst amount, NaBH4 concentration and hydrolysis reaction temperature. The obtained GAKScat was characterized by ICP-MS, elemental analysis, TGA, XRD, FT-IR, Boehm, TEM and SEM analyses and was evaluated for its catalytic activity in the hydrogen production from the hydrolysis reaction of NaBH4. According to the results, the optimal H3PO4 percentage was found as 15%. The maximum hydrogen generation rate from the hydrolysis of NaBH4 with the GAKScat was calculated as 20,199 mL min−1 gcat−1. As a result, it can be said that GAKS treated with 15% H3PO4 as a catalyst for hydrogen production is an effective alternative due to its high hydrogen production rate.