Fossil resources, such as natural gas and petroleum, are finite and have adverse environmental effects. It is desirable to identify and utilize renewable and sustainable resources, such as biomass, to accommodate our energy and material needs. However, biomass is often highly functionalized with oxygen and other heteroatoms, whereas petroleum contains only carbon and hydrogen. Therefore, the ability to reduce the oxygen content of biomass is a critical step in efforts to incorporate biomass-derived feedstocks into chemical processes. A promising chemical reaction in this direction is deoxydehydration (DODH), which converts a vicinal diol into an olefin. In the recent past, rhenium has been used successfully to catalyze the DODH reaction. However, rhenium is not a practical industrial catalyst due to its high cost and low abundance in the earth’s crust. This project investigates whether molybdenum can serve as an efficacious substitute for rhenium to catalyze the DODH reaction, because of molybdenum’s similar chemical properties and lower cost. A series of novel and known molybdenum complexes was synthesized using salan ligands with various electronic and steric properties. The reactivity and selectivity of these complexes as DODH catalysts was observed under differing conditions and with differing diol substrates. Using this class of complexes, near complete conversion of the substrate was observed, with 20 % to 60 % selectivity for the desired olefin product. Moreover, trends were observed in the efficacy of the tested complexes according to the steric and electron withdrawing or donating properties of their ligands.

Molybdenum salan complexes as catalysts for deoxydehydration of vicinal diols

255th National Meeting (2018)

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