CAREER: Selectivity Control in Methanol-to-Hydrocarbons Catalysis by Manipulating the Hydrocarbon Pool

能源显然是21世纪的一个全球性重大挑战问题。运输燃料是一个重要组成部分，因为目前还没有可行的世界级规模的替代碳基燃料。为了满足不断增长的需求，同时从石油转向石油，最大限度地提高碳和能源效率，将煤炭、生物质和天然气等碳源转化为这些产品至关重要。在这种转化的所谓的C1路线中，碳源与水蒸气和/或氧气反应生成合成气(CO H2)，然后再与多种产物反应。甲醇就是这些产物中的一种，它可以产生碳氢燃料。美国国家科学院2009年发表的一份题为《来自煤炭和生物质的液体运输燃料》的报告设想，将甲醇转化为碳氢化合物(MTH)是一个大规模的商业过程，可能会影响未来的运输燃料行业。MTH化学中的潜在挑战是选择性地只生产所需的碳氢化合物产品。Mobil几十年前就已将MTG(甲醇制汽油)商业化，自那以来，通过改变所用沸石催化剂的参数，只实现了很小的选择性改进。如何实现更好的碳效率和选择性控制仍然是个问题。明尼苏达大学双城分校化学工程系的Aditya Bhan教授提出，当我们同时控制这些反应的催化剂和助催化剂时，会产生更好的控制。机理研究表明，甲醇的反应是通过一个碳氢化合物储藏进行的。假设沸石孔是纳米反应器，其中酸中心和油气藏起到了协同催化剂的作用。初步数据表明，用其他有机分子作为添加剂改变碳氢化合物的性质确实会显著改变从反应器出来的产品。Bhan提出了一个实验计划，最终将使他能够通过添加各种添加剂来系统地调整MTH的选择性，这些添加剂与适当的沸石催化剂结合在一起，可以更有效地从C1前体生产更高辛烷值汽油范围的碳氢化合物或轻聚合物等级的烯烃。更广泛的影响是，高选择性和原子效率的MTH催化剂系统的开发将导致用于非石油资源加工的新的热化学工艺，以满足对高能量密度和可替代燃料的需求，以应对运输燃料的挑战。这项拟议的计划使Bhan能够将化学催化研究与教育和宣传部分结合起来，这些部分突出了化学工程在能源转换领域的重要性。教育将通过招募和指导能源研究活动中代表性不足社区的本科生，以及与明尼阿波利斯/圣保罗地区K-12学校的课程开发外联计划来加强。该奖项由化学、生物工程、环境和运输系统部门的催化和生物催化计划以及化学部门的化学催化计划联合颁发。

Energy is clearly a global grand challenge problem for the 21st century. Transportation fuels are a significant component, as there are no viable, world class scale alternatives to carbon-based fuels. To meet the constantly increasing demands while moving from petroleum, it will be essential to maximize carbon and energy efficiency for conversion of carbon sources such as coal, biomass, and natural gas into these products. In the so-called C1 route for this conversion, the carbon sources are reacted with steam and/or oxygen to produce synthesis gas (CO + H2), which can then be reacted to a broad slate of products. Methanol is one of these products which leads to hydrocarbon fuels. A 2009 report by the US National Academies titled Liquid Transportation Fuels from Coal and Biomass envisions methanol-to-hydrocarbons (MTH) as a large-scale commercial process that could impact the transportation fuel sector in the future. The underlying challenge in MTH chemistry is to do a selective job of producing only the hydrocarbon products desired.Mobil has commercialized MTG (methanol-to-gasoline) decades ago, and since then, only minor selectivity modifications have been achieved through modifying the parameters of the zeolite catalyst used. How to achieve better carbon efficiency and selectivity control remains the question. Prof. Aditya Bhan of the Department of Chemical Engineering at the University of Minnesota, Twin Cities proposes that better control will result when we manipulate both the catalyst and co-catalyst for these reactions. Mechanistic studies have shown that the reactions of methanol proceed through a hydrocarbon pool. The hypothesis is that the zeolite pores are nanoreactors in which the acid site and the hydrocarbon pool function as co-catalysts. Preliminary data have demonstrated that changing the nature of the hydrocarbon pool with other organic molecules as additives does significantly change the products coming out of the reactor. Bhan proposes an experimental program which will ultimately allow him to systematically tune selectivity in MTH by the addition of various additives which are combined with the appropriate zeolite catalysts resulting in making higher octane gasoline range hydrocarbons, or alternatively, light polymer grade olefins, more effectively from C1 precursors. The broader impact is the development of highly selective and atom efficient MTH catalyst systems will lead to new thermochemical processes for the processing of non-petroleum resources to meet the demand for high-energy density and fungible fuels to address the transportation fuel challenge. This proposed program allows Bhan to integrate research on chemical catalysis with education and outreach components which highlight the importance of chemical engineering in the area of energy conversion. Education will be enhanced by recruiting and mentoring undergraduate students from under-represented communities in energy research activities, and by an outreach program for curriculum development with K-12 schools in the Minneapolis/St. Paul area. This award is jointly made by the Catalysis and Biocatalysis Program of the Chemical, Bioengineering, Environmental, and Transport Systems Division and the Chemical Catalysis Program of the Division of Chemistry.