H2 Reduction-Mediated Reaction Pathway Switching in Bimetallic Pt–WOx Catalysts: Shifting Fatty Acid Deoxygenation from Decarboxylation to Decarbonylation

The decarbonylation of fatty acids represents a promising route for producing value-added alkenes; however, the thermodynamic preference for decarboxylation over decarbonylation poses a fundamental challenge. Herein, we developed a hydrogen-reducible PtWOx/SiO2 bimetallic catalyst that enables pathway switching from predominant decarboxylation to selective decarbonylation. The PtWOx/SiO2–Air catalyst calcined in air exhibited outstanding fatty acid decarboxylation performance, achieving 99% stearic acid conversion and 85% heptadecane selectivity. In contrast, the hydrogen-reduced PtWOx/SiO2–H2 catalyst shifted the deoxygenation pathway of stearic acid from decarboxylation to decarbonylation, increasing the selectivity for heptadecene from 5.9 to 57.1%. Structural characterization revealed that Pt nanoparticles were surrounded by amorphous WOx domains, creating abundant Pt–WOx interfaces that strengthened fatty acid adsorption. X-ray photoelectron spectroscopy (XPS) and CO–DRIFTS showed that hydrogen reduction converted PtO2/WOx to Pt/WOx, while presenting a strong metal–support interaction (SMSI) between Pt and WOx, inducing electron transfer from Pt to W and generating Ptδ+. These Ptδ+ sites weakened the d-2π* back-donation effect and lowered the CO adsorption energy, thereby promoting decarbonylation. Density functional theory (DFT) calculations further confirmed that the higher binding energy barriers for C3H7* and H* in Pt/WOx, along with the lower desorption energy barriers for CO, favored the decarbonylation pathway. This work provides a catalyst design strategy with electronic modulation to overcome the thermodynamic limitations of fatty acid decarbonylation.