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

国家科学基金会化学部的化学催化计划支持利哈伊大学的伊斯雷尔·E·瓦克斯教授研究基础科学，这些科学可以导致开发用于烯烃歧化反应的高选择性负载型WO_3/SiO_2催化剂。由于多相负载型WO_3/SiO_2催化剂体系对低碳烯烃具有优异的歧化反应特性，因此本研究主要集中在多相负载型WO_3/SiO_2催化剂的烯烃歧化反应上，使其成为工业催化剂的首选。这一研究方案的假设是，二氧化硅载体上的表面氧化钨物种存在着独特的分子结构和氧化态，这是导致C2-C4烯烃歧化反应的催化活性中心。这项研究的目的是利用最先进的原位光谱技术，结合分子设计的模型单位催化剂，直接确定多相负载型WO_3/SiO_2烯烃歧化催化剂的分子/电子催化活性/选择性关系。参与拟议研究项目的学生将接受指导，以培养他们的批判性思维能力、实验设计和数据分析方法、有效的口头和书面沟通技能以及研究道德。将特别重视从代表性不足的群体中招收研究生和本科生。这些学生将参加利哈伊的年度外展项目选择，涉及高中教师和中学女学生。丙烯(C3)是石化工业的第二大原料，丙烯短缺已经形成，并将在未来十年继续增加。为了满足这一需求，石化工业正转向通过C2+C4-2 C3反应来催化烯烃歧化反应，而提高该反应的催化剂性能是一个关键挑战。负载型WO_3/SiO_2催化剂加深了对该反应的基本认识，有助于合理设计具有更高碳效率的工业多相烯烃歧化催化剂，展示多相催化研究的现代方法。

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.