Structure-Activity Relationships in Acid-Catalyzed Alcohol Dehydration Reactions

The demand for primary energy sources and commodity chemicals has increased worldwide, as the global standards of living increase. The current reserves of petroleum have been declining, necessitating the use of alternative paths for energy generation and chemicals production. Biomass-derived fuels and chemicals offer an economically and environmentally attractive alternative to petroleum resources, diversifying our energy portfolio. Alcohols and polyols compose part of the biomass-derived product spectrum, which can be further converted to value-added chemicals. One important route is catalytic dehydration of alcohols – important reaction in biomass conversion with a high degree of industrial relevance. We used electronic structure calculations to study acid-catalyzed alcohol dehydration in production of olefins and ethers – used in the synthesis of commodity chemicals and plastics. We focused on understanding dehydration reaction mechanisms, identifying rate-determining steps along reaction coordinates and identifying key physicochemical properties of catalysts that exhibit both Lewis- and Brønsted acidity, along with alcohols of varying size and substitution. We have found that structure-activity relationships (SARs) can be developed by accounting for acid-base properties of catalysts and structure of reactants. Reaction barriers were found to correlate with key physicochemical properties, used as reactivity descriptors towards development of predictive models. These properties can be used to inform the screening of a range of catalytic systems for the purpose of biomass upgrading via acid-catalyzed dehydration reactions. In this work we report SARs developed for a series of catalysts and alcohols of varying size and substitution. The models exhibit flexibility in capturing fundamental system properties for a range of catalysts and reactant alcohols. Additionally, leveraging design principles based on structure-function observations, we designed first-of-their-kind, active and selective catalysts for the production of olefins from alcohols. SARs developed for alcohol dehydration on metal oxides were found to capture reactivity trends in alkane dehydrogenation over Al2O3, accounting for catalyst acid-base properties and stability of intermediates at key transition states