Collaborative Research: Selective Oxidation Catalysis on Oxides Containing Pores of Molecular Dimensions

我们的现代生活水平取决于我们的交通所需的燃料，以及用于制造许多消费品的许多材料的化学品。这些燃料和化学品主要来自化石燃料通过催化反应转化为增值化学品和材料。因此，通过更有效地使用和转化这些原材料，我们生活方式的环境足迹可以显著减少。催化改质反应的一个实例是将页岩气转化为散装化学品和燃料前体。 页岩气中的短的饱和烃分子（轻质烷烃）转化为烯烃导致更具反应性，因此更有价值的化学中间体。 这种转化涉及去除氢原子和插入更具反应性的碳-碳双键。 为了在低温下进行该转化，需要使用催化剂，一个这样的例子是混合金属氧化物催化剂。本项目的目的是了解如何设计混合金属氧化物中孔的大小和形状，以更好地选择性催化氧化烷烃到烯烃的反应。本计画将探讨有序本体过渡金属氧化物催化剂中微孔在小分子烷烃和烷醇的选择性烃氧化中的作用。有序的M1相混合氧化物含有尺寸与反应物的动力学直径相似的一维孔;实例包括Mo、V、Te和Nb的M1相混合氧化物和Mn氧化物的八面体分子筛。该项目将把直链烷烃与支链烷烃的氧化速率比与孔尺寸相关联，并考虑到显示尺寸排他性的孔尺寸。动力学和密度泛函理论（DFT）将探测孔几何形状，反应物几何形状和表面反应性的变化的选择性。预期货车德瓦尔斯稳定化和空间位阻可限制向次级副产物的转化，这可通过绕过次级氧化反应的热力学驱动力而增强选择性以生成次级副产物。计划开展的教育和外联活动将促进对多相催化及其在应对可持续化学品生产和能源效率挑战方面的作用的了解。这些活动将针对来自贫困背景的学生，旨在提高他们在科学和工程领域的保留率。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Our modern standard of living depends upon the fuels that are needed for our transportation, and the chemicals that are used to make many of the materials of our many consumer products. These fuels and chemicals are predominantly derived from the conversion of fossil fuels into value-added chemicals and materials via catalytic reactions. Thus, the environmental footprint of our lifestyles can be significantly reduced with more efficient use and conversion of these raw materials. One example of a catalytic upgrading reaction is the conversion of shale gas to bulk chemical and fuel precursors. Conversion of the short, saturated hydrocarbon molecules (light alkanes) within shale gas to alkenes leads to a more reactive, and thus more valuable, chemical intermediate. This conversion involves the removal of hydrogen atoms and insertion of a more reactive carbon-carbon double bond. To perform this conversion at low temperatures requires use of a catalyst, and one such example is a mixed metal oxide catalyst. The objective of this project is to understand how the size and shape of pores within the mixed metal oxide may be engineered to more selectivity catalyze the oxidative alkane to alkene reaction. This project will probe the role of micropores in ordered bulk transition metal oxide catalysts in the selective hydrocarbon oxidation of small alkanes and alkanols. Ordered M1 phase mixed oxides contain one dimensional pores that are similar in size to the kinetic diameters of the reactants; examples include M1 phase mixed oxides of Mo V, Te and Nb and octahedral molecular sieves of Mn oxides. The project will correlate the oxidation rate ratios of linear versus branched alkanes to cycloalkanes to pore dimension, with consideration of pore sizes that exhibit size exclusivity. Kinetic and density functional theory (DFT) will probe selectivity with variations in pore geometry, reactant geometry, and surface reactivity. It is anticipated van der Walls stabilizations and steric hindrance may limit conversion to secondary byproducts, which may enhance selectivity by bypassing the thermodynamic driving forces for secondary oxidation reactions to secondary byproducts. Planned education and outreach activities will promote understanding of heterogeneous catalysis and its role in meeting the challenges of sustainable chemical production and energy efficiency. These activities will target students from underprivileged backgrounds, with an aim to increase their retention in science and engineering fields.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.