Deciphering Reactivity Factors of Cu(II)–Pd(0) Engaged in Porous Organic Polymer toward Catalytic Hydrogenolysis of 5-Hydroxymethylfurfural to 2,5-Dimethylfuran

In recent years, catalytic biomass valorization has held significant promise in addressing both environmental concerns and the growing demand for sustainable chemical feedstocks. By efficiently converting biomass into valuable chemicals and fuels using catalytic processes, we can reduce reliance on fossil fuels while mitigating carbon emissions, thus fostering a more sustainable and greener economy. In this direction, there has been considerable interest among researchers in the selective hydrogenation of biomass-derived 5-hydroxymethylfurfural (5-HMF) to produce the unique furanic scaffold 2,5-dimethylfuran (DMF). This interest stems from its symmetrical structure and widespread use as a monomer for synthesizing cross-linked polyesters and polyurethane. Emulating this perspective, we have effectively developed a cost-efficient and scalable method for synthesizing a nitrogen-enriched porous organic polymer (POP) named DAB, employing a FeCl3-assisted Friedel–Crafts alkylation condensation-polymerization technique. Moreover, a straightforward solid-phase hydrogenation approach at elevated temperatures has been utilized to produce atomically dispersed CuPd bimetallic nanospheres supported on the POP, either within or outside the cavity. These nanospheres maintain stable Cu0/2+ and Pd0/2+ active surface species, forming catalytic systems known as CuPd@DABs. The catalysts were employed for the selective hydrogenation of 5-HMF produced from biomass, yielding 81.5% selectivity of DMF under optimized reaction conditions and showing excellent activity in the transformation of HMF. The boosted activity observed in the case of CuPd@DAB-1 can be coherently attributed to the presence of Cu–Pd alloy nanospheres, which is rigorously supported by comprehensive experimental investigations. DRIFT adsorption study was performed to analyze the adsorption behavior of HMF on CuPd@DAB-1 and CuPd@DAB-2 catalysts, which demonstrated significant red shifts in the peaks of HMF for CuPd@DAB-1, indicating strong interfacial interactions, while for CuPd@DAB-2, the peaks were similar to pure HMF. These interactions are attributed to the surface-exposed Cu–Pd metal nodes in CuPd@DAB-1, leading to higher catalytic activity compared to CuPd@DAB-2. Computational investigations further unwrapped the role of synergistic Cu–Pd interactions in establishing the reaction kinetics and impacting the product activity and selectivity.