Theoretical Investigation of the Reaction Mechanism of the Guaiacol Hydrogenation over a Pt(111) Catalyst

The reaction mechanism of the mild hydrogenation of guaiacol over Pt(111) has been investigated by density functional theory calculations and microkinetic modeling. Our model suggests that at 573 K, catechol is the preferred reaction product and that any deoxygenation to, for example, phenol or benzene is at least 4 orders of magnitude slower than the production of catechol. Slow deoxygenation of guaiacol can occur by decarbonylation and possibly by hydrogenation of the phenyl ring followed by C–OH bond cleavage. Direct −OH removal without activation of the phenyl ring is found to be at least 5 orders of magnitude slower. Overall, this study suggests that Pt(111) sites are not active deoxygenation sites and that the experimentally observed deoxygenation activity of Pt catalysts originates likely from the involvement of the catalyst support or Pt step and corner sites.