SusChEM: Molecular Level Foundation for Olefin Metathesis by Heterogeneous Supported WO3/SiO2 Catalysts

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The Chemical Catalysis Program in the Chemistry Division at the National Science Foundation supports Professor Israel E. Wachs from Lehigh University to investigate the underlying science that can lead to the development of highly selective supported WO3/SiO2 catalysts for olefin metathesis. This research proposal focuses on olefin metathesis by heterogeneous supported WO3/SiO2 catalysts because of this catalyst system's outstanding metathesis characteristics for light olefins that have made it the industrial catalyst of choice. The hypothesis of this research proposal is that there is a unique molecular structure and oxidation state for the surface tungsten oxide species on the silica supports, the catalytic active site, that is responsible for C2 - C4 olefin metathesis. The objective of the proposed research is to employ modern state-of-the-art in situ spectroscopic techniques in conjunction with molecularly designed model single site catalysts to directly determine the molecular/electronic-catalytic activity/selectivity relationships for heterogeneous supported WO3/SiO2 olefin metathesis catalysis. The students involved in the proposed research project will be mentored to develop their critical thinking skills, experimental design and data analyses approaches, effective oral and written communications skills and research ethics. Special emphasis will be made to recruit graduate and undergraduate students from underrepresented groups. The students will participate in Lehigh's annual outreach program CHOICES involving high school teachers and middle school female students. Propylene (C3) is the second largest feedstock for the petrochemical industry and a shortage of propylene has developed that will continue to increase over the next decade. To meet this demand, the petrochemical industry is turning to olefin metathesis catalysis via the C2 + C4 - 2 C3 reaction, and improving catalyst performance for this reaction is a key challenge. Increased fundamental understanding of this reaction by supported WO3/SiO2 catalysts has the potential to assist in the rational design of improved industrial-type heterogeneous olefin metathesis catalysts with improved carbon efficiency and showcase the modern approach to heterogeneous catalysis research.