Statistical analysis of the catalytic synthesis of Vinyl acetate over Pd-Cu/ZrO2 nanostructured based catalysts

Catalytic oxidation is a suitable route for the production of oxygenated compounds from lignocellulose biomass, whose processing produce ethylene and AcOH like subproducts in first-generation ethanol production. Furthermore, the development of routes to convert green ethylene from renewable sources, have been motivating other possibles applications like green monomers, fuels, and fine chemicals. In this work we prepared Pd-Cu catalysts over ZrO2 mixed oxides incorporating Al+3 and Ti+4 like promoters. The catalysts were characterized by XRD-in situ, BET, H-2 chemisorption and HRTEM. Catalytic tests were performed through experimental planning. Statistical analyses allowed to find the main correlations of the products. The PCA coefficients revealed that Vinyl acetate monomer formation was influenced by the AcOH and O-2 consumption at low ethylene coverage. Acetaldehyde emerged as an important intermediate for Vinyl acetate monomer synthesis. XRD results showed that the Pd-Cu catalyst exhibit tetragonal/orthorhombic nature with differences in the lattice position. The presence of Cu+2 in the lattice explains the promotion of Vinyl acetate monomer formation due to acetaldehyde formation, AcOH hydrogenation and posterior H-2 spillover, releasing the hydroxyl groups during Vinyl acetate monomer dehydrogenation from the active site. A microkinetical model was achieved from directions of fluctuations, indicating ethylene coupling and AcOH hydrogenation to produce Vinyl acetate monomer (VAM).