Enhanced Biodiesel Synthesis via Interfacial Mass Transfer Intensification in Pickering Emulsions Using an Amphiphilicity-Engineered β-Zeolite Catalyst

Despite advantages in feedstock compatibility and process simplicity for biodiesel production, solid acid catalysis faces severe intrinsic kinetic limitations in multiphasic transesterification reactions. This work overcomes this challenge by constituting a Pickering interfacial catalytic system using an amphiphilicity-engineered β-zeolite that functioned dually as an emulsion stabilizer and solid acid catalyst. Precise amphiphilicity control via organosilane modification (optimal catalyst: HTS β-24, contact angle of triolein of 84°) maximized the emulsion stability and interfacial area (minimal droplet diameter of 14 μm) at intermediate hydrophobicity. Crucially, biodiesel yield correlates directly with emulsion properties (not total acidity), demonstrating interfacial mass transfer as the dominant rate-limiting step. Leveraging this intensified mass transfer, an ultrahigh 98% methyl oleate (biodiesel) yield from triolein and methanol was achieved under mild conditions (80 °C, 3 h). Notably, the present system still delivered 89% yield without continuous agitation, outperforming the literature under milder conditions and enabling facile catalyst regeneration. This strategy synergizes interfacial mass transfer intensification with solid acid catalysis, advancing the process efficiency, scalability, and sustainability for biodiesel synthesis.