Sustainable Catalysts from Recovered Palladium and Biomass Derived Carbon for the Reduction of a Boscalid® Precursor

Abstract

This work reports the development of sustainable Pd/C catalysts prepared from palladium recovered from spent three-way catalytic converters (TWCs) and supported on biomass-derived activated carbon. Date pits and coconut husks were employed as renewable carbon sources, and ammonium formate was selected as a green hydrogen donor in the bioderiveable BuOH as a green solvent, for the reduction of 4-chloro-2-nitrobiphenyl, a key precursor to the agrochemical Boscalid®. The catalysts showed high activity and selectivity, achieving up to 86% yield of the desired aniline product under optimized conditions. XPS and TEM analyses confirmed the presence of Pd nanoparticles, with catalytic performance strongly influenced by the carbonization method and Pd⁰/Pd²⁺ ratios. Quinoline was used to suppress over-reduction, further enhancing selectivity. These results demonstrate the feasibility of combining recovered palladium with renewable carbon supports to generate effective and greener hydrogenation catalysts, reducing reliance on mined palladium and advancing sustainable approaches in fine chemical synthesis.