Multi-performance reusable biochar phosphoric acid as solid acid nanocatalyst for biodiesel production and multicomponent organic reactions.

The biochar catalyst's eco-friendly properties meet the rising demand for greener chemical processes by decreasing dependence on hazardous materials and lessening environmental impact. Its production from renewable biomass supports a circular economy, fostering waste valorization and resource efficiency. In this work, biochar phosphoric acid, as a solid acid, was impregnated with H3PO4 and pyrolyzed at 600 °C for two hours to create a nano-catalyst. The structure of the catalyst synthesized in this work is biochar, in which the phosphoric acid groups are placed into the surface through covalent bonding due to pyrolysis at high temperature, resulting in a solid phosphoric acid catalyst. FT-IR, XRD, SEM, EDS, and BET methods were used to satisfactorily characterize the biochar phosphoric acid as a Bronsted acid catalyst. Biochar phosphoric acid showed remarkably efficient catalytic activity for biodiesel production and 1-Amidoalkyl-2-Naphthols, Tetrahydrobenzo[b]pyran and 1,8-Dioxo-octahydroxanthene reactions. Additionally, the biochar phosphoric acid catalyst demonstrated recyclability for up to five recycling cycles without appreciably reducing catalytic performance. This green catalyst's benefits include good to exceptional efficiency, quick response times, and simple isolation and recyclability due to its heterogeneity.