Preparation process optimization and nanoscale size effects of low-loading Pd/C catalysts for rosin disproportionation

• The study optimizes low-loading Pd/C catalysts for rosin disproportionation. • A series of Pd particles with mean diameters from 3.42 to 6.88 nm were synthesized. • Optimum experimental conditions were obained using RSM-BBD model approach. • Smaller Pd nanoparticles (3.42 nm) showed enhanced catalytic activity. Designing cost-effective noble metal catalysts for industrial applications demands precise control over nanoparticles (NPs) size and synthesis protocols. This study focuses on optimizing low-loading (1.00 wt%) Pd/C catalysts for rosin disproportionation (RD), targeting enhanced catalytic efficiency through nanoscale synthesis control. Three synthesis strategies (impregnation, hydrosol, and deposition-precipitation) combined with reductants (glycol, hydrazine hydrate, and NaBH 4 ) were compared to regulate Pd NPs size. The NaBH 4 /Pd molar ratio (22.7), temperature (65 °C), and duration (4 h) were systematically optimized via response surface methodology (RSM). Advanced characterization (High-angle annular dark-field scanning transmission electron microscope (HR-TEM), X-ray Diffraction (XRD), specific surface area (SSA), X-ray photoelectron spectroscopy (XPS)) correlated NP size (3.42–6.88 nm) and surface valence states with catalytic performance. The deposition-precipitation method with NaBH 4 reduction produced relatively small Pd NPs (3.42 nm) with moderate dispersion, achieving a 52.64% dehydroabietic acid (DAA) yield and 0.10% residual abietic acid (AA), meeting LY/T 1357–2008 standards. RSM optimization further increased the DAA yield to 53.54%. A distinct inverse correlation between Pd NP size (3.42–6.88 nm) and DAA productivity highlighted the critical role of nanoscale engineering: Smaller NPs increased accessible surface Pd atoms, accelerating hydrogen transfer kinetics. This work establishes a scalable framework for industrial catalyst design by integrating nanoscale control of Pd NPs with process optimization to minimize precious metal usage while maximizing performance.