Towards Sustainable Hydrocarbon Biorefineries: Deoxygenation of Biomass Oxygenates to Hydrocarbons via Methane

实现可持续碳氢化合物(HC)生物精炼的最重要的技术挑战之一是从原料中去除氧气，氧气通常占木质纤维生物质的35wt%。据估计，最接近的脱氧、加氢脱氧和加氢裂化技术每吨生物质使用大约66公斤氢气。这种氢气需求影响了碳氢化合物生物炼油厂的长期可持续性。因此，需要一种有效和可持续的机制来去除生物可再生原料中的氧气。甲烷是一种富含氢气的气体，可以通过可持续的工艺生产。这项提议的总体目标是了解甲烷在热解条件下与生物质衍生的含氧物在双功能催化剂上接触时发生的基本催化过程。智力价值耗氢反应和同时产氢反应的动力学耦合的可能性是富氧生物质原料脱氧的基础。具体地说，生物质衍生含氧物的芳构化是耗氢反应。在这个过程中，苯、甲苯和二甲苯(BTX)通常是通过脱水反应生成的，副产品是水。甲烷的制氢反应是甲烷水蒸气重整和甲烷芳构化，假设甲烷可以与生物质热解蒸气(含氧物)直接偶联，并在合适的金属担载的ZSM-5双功能催化剂上通过两条途径脱氧成烃：(1)甲烷水蒸气重整和含氧物芳构化；(2)甲烷芳构化和含氧物芳构化。在第一个偶联反应中，甲烷水蒸气重整形成的氢气用于含氧物的芳构化。含氧芳构化脱水生成的水用于甲烷水蒸气重整。这种偶联反应的最终产物是碳氢化合物和二氧化碳。在第二个偶联反应中，甲烷被芳构化，生成BTX(苯、甲苯、二甲苯)和氢气。在拟议的研究中，将阐明在ZSM-5催化剂上，甲烷与模型含氧物葡萄糖在精选的含金属(Sn、Ni、Ce、Ru或Mo2C)双功能催化剂存在下发生的反应。通过这项模型研究确定的候选双功能催化剂将被用来探索生物质成分(纤维素、木质素、固体生物质和生物油)在甲烷存在下催化热解时产生的碳氢化合物的光谱。这项研究将提供对富氧底物和甲烷-历史上难以激活的缺氧富氢底物-时在催化剂表面发生的化学的基本理解。这项研究具有潜在的变革性，因为它提出了一种从不需要氢的生物质中生产碳氢化合物的新途径。这项研究具有实际意义，因为现有的炼油厂基础设施可以用来从生物质中提取具有商业价值的碳氢化合物。广泛影响除了培养研究生，教育和推广计划还侧重于在实践研究环境中教与学本科生。具体地说，拟议的教育活动以REACH方案(针对学业困难的研究经验)的发展为特色。在拟议的REACH计划中，来自代表不足的群体的学生在学业上存在风险(GPA为2.5)，并与没有风险的学生配对。这个团队在他们本科课程的早期就获得了实践研究经验。这些学生的学业进步将在他们的本科生涯中被跟踪，以评估在团队环境中让他们及早接触实践研究是否有助于激发他们对学习的热情，并促进他们对工程项目的保留。

0965772FernandoOne of the most important technical challenges in the realization of sustainable hydrocarbon (HC) biorefineries is the removal of oxygen from the feedstock, which typically constitutes up to 35 wt% of lignocellulosic biomass. The closest technologies for deoxygenation, hydrodeoxygenation and hydrocracking, are estimated to use approximately 66 kg of hydrogen per metric ton of biomass. This hydrogen gas need affects the long-term sustainability of HC biorefineries. Consequently, there is need for an effective and a sustainable mechanism to remove oxygen from biorenewable feedstocks.Methane is a hydrogen-rich gas which can be produced by sustainable processes. The overall objective of this proposal is to understand the fundamental catalytic processes that occur when methane contacts biomass-derived oxygenates on bi-functional catalysts under pyrolysis conditions.Intellectual MeritThe possibility of kinetically coupling a hydrogen-consuming reaction with a concurrent hydrogen-producing reaction is the basis for oxygen-rich biomass feedstock deoxygenation. Specifically, aromatization of biomass-derived oxygenates is the hydrogen consuming reaction. During this process, benzene, toluene and xylene (BTX) are typically formed by dehydration reactions, which produce water as byproduct. The hydrogen producing reactions are methane steam reforming and methane aromatization.It is hypothesized that methane can be directly coupled with biomass-derived pyrolytic vapors (oxygenates) and deoxygenated into hydrocarbons over an appropriate metal supported ZSM-5 bi-functional catalyst via two pathways: (1) methane steam reforming and oxygenate aromatization, or (2) methane aromatization and oxygenate aromatization. In the first coupling reaction, hydrogen gas formed during methane steam reforming is used for the aromatization of oxygenates. Water formed during oxygenate aromatization via dehydration is used for methane steam reforming. The ultimate products of this coupling reaction are hydrocarbons and carbon dioxide. In the second coupling reaction, methane is aromatized to produce BTX (benzene, toluene, xylene) and hydrogen gas. Oxygenates utilize the hydrogen formed and aromatize by dehydration, removing oxygen as water.In the proposed research, the reactions that occur between methane and the model oxygenate glucose in the presence of selected bi-functional catalysts that contain metals (Sn, Ni, Ce, Ru or Mo2C) on ZSM-5 catalysts will be elucidated. Candidate bi-functional catalysts identified by this model study will then be used to explore the spectrum of hydrocarbon products generated when when biomass constituents (cellulose, lignin, solid biomass and bio-oil) are catalytically pyrolyzed in the presence of methane.This research will provide fundamental understanding on the chemistry that occurs at a catalyst surface when an oxygen-rich substrate and methane - an oxygen-deficient, hydrogen-rich substrate that is historically difficult to activate - are brought together. The research is potentially transformative because it suggests a new route to produce hydrocarbons from biomass that does not require hydrogen. The research has practical implications, because existing petroleum refinery infrastructure could be used to formulate commercially valuable hydrocarbons from biomass.Broader ImpactsIn addition to the training of graduate students, the education and outreach plan focuses on undergraduate student teaching and learning in a hands-on research environment. Specifically, the proposed education activities feature the development of the REACH program (Research Experiences for the Academically Challenged). In the proposed REACH program, students from under-represented groups who are academically at risk (2.5 GPA) are paired with students who are not at risk. This team is provided with hands-on research experiences early in their undergraduate program. The academic progress of these students will be tracked during the course of their undergraduate career to evaluate whether or not exposing them early on to hand-on research in this team environment helps stimulate their excitement towards learning and promotes their retention in engineering programs.