Molecular Design of Advanced Supported ReOx/Al2O3 Olefin Metathesis Catalysts

Soe Lwin and Israel E. Wachs

Operando Molecular Spectroscopy and Catalysis Laboratory

Department of Chemical Engineering

Lehigh University, Bethlehem, PA 18015, USA

Olefin metathesis interconverts C=C bonds in hydrocarbons and can be tailored to produce an alkene of any desired length. Its versatility opens up a whole new series of reactions and results in numerous industrial applications that produce important petrochemicals, oleochemicals, polymers and specialty chemicals. Heterogeneous alumina and alumina-silica supported rhenium oxides (ReOx) are extensively investigated due to their catalytic activity at near room temperature. Despite decades of catalysis research, the exact nature of catalytic active sites is not well understood because of the absence of detailed knowledge at molecular level and lack of modern characterization techniques in the past.
Extensive in situ and operando Raman, UV vis and IR studies, steady-state kinetics and temperature programmed surface reaction (TPSR) experiments with deuterium labeled olefins were undertaken for the first time to obtain unprecedented insights about the catalytic active sites (their anchoring sites, coordination and oxidation states) and surface kinetics to unravel the fundamental molecular structure-reactivity relationships. These new fundamental insights
enabled the molecular design of advanced supported ReOx/Al2O3 olefin metathesis catalysts.