Synthesis and catalytic performance of Pd NPs-doped polymer brushes for optimization and modeling of NaBH4 hydrolysis

Abstract

Sodium borohydride (NaBH₄) is considered one of the most promising materials for hydrogen (H₂) production. For this, designing a high-performance and cost-effective catalyst is an important step in developing a sustainable hydrogen source. Here, firstly, cross-linked polymer brushes were grafted on the surface of pumice minerals (P4VP/PMC). Then, Pd nanoparticles were reduced on the surface using the NaBH₄ reduction method (Pd-P4VP/PMC). The composition and structure of the catalyst were analyzed using diverse techniques. Response surface methodology (RSM) was used to optimize and model the impact of the main factor interactions during the hydrolysis process. According to the quadratic model obtained, catalyst concentration 2.192 mg/mL; temperature 57.3 °C; NaBH₄ concentration 186.6 mM, and NaOH 5.435 wt% were determined to be optimum values using the matrix method. At these values, the maximum hydrogen generation rate (HGR) was 8732.85 mL H₂/(g_cat. min.) Also, reusability was tested and after five cycles the catalytic activity of Pd-P4VP/PMC was reduced by only ∼30 %. As a result, the synthesized catalyst exhibited relatively low activation energy (26.85 kj/mol) and high HGR (8732.85 mL H₂/(g_cat. min.)), clearly demonstrating the superiority of Pd-P4VP/PMC as a catalyst for hydrogen generation from hydrolysis of NaBH₄.