High-Performance Nickel Phosphide Confined in SBA-15 for Low-Temperature Hydrogenation of Biomass-Derived Compounds

Developing cost-effective and highly active catalysts for biomass conversion under mild conditions is crucial but challenging. In this work, we present an efficient strategy for confining ultrafine nickel phosphide nanoparticles within the mesoporous channels of SBA-15, using phytic acid (PA) as both a chelating agent and an environmentally friendly phosphorus source. The optimal catalyst, 0.3PNi/SBA-15, demonstrates great catalytic performance for the selective hydrogenation of methyl levulinate (ML) into γ-valerolactone (GVL) using molecular H₂ as a hydrogen source, achieving a high GVL mass productivity of 32.4 mol GVL·mol Ni^-1·h^-1 at a low temperature of 90 °C, with water as the solvent. This performance is over 54 times higher than that of pristine Ni/SBA-15 and outperforms recently reported state-of-the-art nonprecious catalysts. Detailed characterizations and density functional theory calculations (DFT) reveal that precoating the inner surface of the SBA-15 channels with PA plays a key role in dispersing and forming ultrafine Ni₃P active nanoparticles. The Ni^δ+ species generated in ultrafine Ni₃P nanoparticles through electron transfer from Ni to P exhibit strong adsorption of ML and rapid desorption of GVL, enabling faster recovery of the active sites and consequently contributing to superior performance. Furthermore, 0.3PNi/SBA-15 also exhibits high catalytic performance for the hydrogenation of a variety of aldehydes, ketones, and nitroarenes. This work provides a convenient strategy for designing promising metal phosphide catalysts for upgrading biomass-derived compounds.