Deoxydehydration of 1,4-anhydroerythritol over anatase TiO2(101)-supported ReOx and MoOx

Abstract

Heterogeneously catalyzed deoxydehydration (DODH) ordinarily occurs over relatively costly oxide supported ReO_x sites and is an effective process for the removal of vicinal OH groups that are common in biomass-derived chemicals. Here, through first-principles calculations, we investigate the DODH of 1,4-anhydroerythritol over anatase TiO₂(101)-supported ReO_x and MoO_x. The atomistic structures of ReO_x and MoO_x under typical reaction conditions were identified with constrained thermodynamics calculations as ReO₂(2O)/6H–TiO₂ and MoO(2O)/3H–TiO₂, respectively. The calculated energy profile and developed microkinetic reaction model suggest that both ReO₂(2O)/6H–TiO₂ and MoO(2O)/3H–TiO₂ exhibit a relatively low DODH activity at 413 K. However, at higher temperatures such as 473 K, MoO(2O)/TiO₂(101) was found to exhibit a reasonably high catalytic activity similar to ReO₂(2O)/6H–TiO₂, consistent with a recent experimental study. Mechanistically, the first O–H bond cleavage of 1,4-anhydroerythritol and the dihydrofuran extrusion were found to be the rate-controlling steps for the reaction over ReO₂(2O)/6H–TiO₂ and MoO(2O)/3H–TiO₂, respectively. Thus, this study clarifies the mechanism of the DODH over oxide-supported catalysts and provides meaningful insight into the design of low-cost DODH catalysts.