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

我们的现代生活水平依赖于我们运输所需的燃料，以及用来制造我们许多消费品的许多材料的化学品。这些燃料和化学品主要是通过催化反应将化石燃料转化为增值化学品和材料而获得的。因此，通过更有效地使用和转换这些原材料，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例子是将页岩气转化为大宗化学和燃料前体。页岩气中的短的饱和碳氢化合物分子(低碳烷烃)转化为烯烃会导致更活跃的化学中间体，因此更有价值。这种转化包括去除氢原子和插入更活泼的碳-碳双键。要在低温下进行这种转化需要使用催化剂，其中一个例子是混合金属氧化物催化剂。该项目的目的是了解如何改变混合金属氧化物中的孔的大小和形状，以更有选择性地催化氧化烷烃到烯烃的反应。本项目将探索有序体相过渡金属氧化物催化剂中微孔在小分子烷烃和烷烃选择性氧化反应中的作用。有序的M1相混合氧化物含有一维的孔，其大小与反应物的动力学直径相似；例如，Mo，V，Te，Nb的M1相混合氧化物和锰氧化物的八面体分子筛。该项目将把直链烷烃和支链烷烃与环烷烃的氧化速率比率与孔尺寸关联起来，同时考虑到显示出尺寸排他性的孔尺寸。动力学和密度泛函理论(DFT)将探索随着孔几何、反应物几何和表面反应性的变化而产生的选择性。预计范德沃尔斯稳定和空间位阻可能会限制向二次副产物的转化，这可能会通过绕过二次氧化反应向二次副产物的热力学驱动力来提高选择性。计划中的教育和宣传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。这些活动将针对贫困背景的学生，旨在增加他们在科学和工程领域的留存。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.