Simultaneous Synthesis of a Microporous Polymer Framework with Embedded Nickel Nanoparticles for Enhanced Selective Hydrogenation of Furfural to Furfuryl Alcohol

The significance of the development of porous organic polymers (POPs) is broadly acknowledged in both academia and industrial communities. Advances in POP synthesis have paved the way for modern technologies in gas separation and storage, photovoltaics, and catalysis. In catalysis, POPs are ideal candidates for the heterogenization of highly active catalytic metal species due to their unique surface porous properties. The design of inexpensive, highly active, and reusable heterogeneous catalysts via robust synthetic techniques is of particular importance in the case of industrial applications in the conversion of biomass-derived platform molecules into value-added chemicals. We present an elegant approach for embedding Ni nanoparticles within a microporous aromatic pyridyl-containing polymer framework to create a heterogeneous catalyst for the hydrogenation of furfural to furfuryl alcohol. This process involves the cyclotrimerization of a dendritic aromatic multifunctional ethynyl-terminated monomer, catalyzed by nickel(II) bis(acetylacetonate). Subsequently, the material is subjected to thermal treatment at 500 °C in an Ar/H 2 atmosphere, facilitating the reduction of Ni 2+ to Ni 0, as confirmed by XPS analysis. This method enables the simultaneous encapsulation of Ni and the formation of the POP framework with a specific surface area of up to 918 m 2 /g and a high micropore content of up to 81%. The reaction conditions were effectively adjusted to alter the porous properties. The catalytic composites demonstrate exceptional activity in the selective hydrogenation of furfural to furfuryl alcohol, achieving selectivity exceeding 99% even with a minimal nickel loading of 0.06 mol %. The presence of pyridyl units in the polymer support, along with high microporosity, enhances both the activity and selectivity of the resulting porous catalytic composites in the hydrogenation of furfural. The catalysts were successfully reused five times without loss of activity. Comprehensive characterization of the catalysts highlighted the significant influence of the porous polymer carrier on the efficiency of hydrogenation and emphasized the role of nitrogen species in catalyst stability.