Collaborative Research: Rational design of bifunctional catalysts for the conversion of Ievulinic acid to gamma-valerolactone

现代石化工业在满足社会需求方面取得了令人印象深刻的效率，通过选择性地转化一些关键的基本化学品。未来自给自足的生物精炼工业也将同样建立在可再生建筑模块的选定平台上，这些可再生建筑模块可能生产运输燃料或商品和特种化学品。最近的一项研究已经确定了10种有前途的生物质衍生物，它们有可能成为未来生物炼油厂的基石。其中，乙酰丙酸（LA）特别有前途，因为它可以通过硫酸水解各种木质纤维素原料以低成本和高产量生产。LA转化为燃料添加剂、化学品和塑料和纺织品单体的过程已经得到证实，但尚未商业化。衍生的化学物质？×-valerolactone （GVL）是一种非常有前途和非常灵活的中间体，从中可以获得这些相同的许多理想的最终产品。尽管GVL有无数的应用，但其大规模生产尚未建立，主要原因是其直接前体LA的纯化存在困难。南卡罗莱纳大学的Andreas Heyden教授和锡拉丘兹大学的Jesse Q. Bond教授认为这些问题都有解决方案，并获得了NSF奖，以建立基础科学，使木质纤维素生物质衍生平台化学GVL在商业规模上的生产可行。在目前的技术状态下，LA必须经过昂贵的纯化方案，以在转化为GVL之前从纤维素水解中去除残留的硫酸。H2SO4必须回收和循环利用，以符合生物精炼过程的长期可持续性。GVL具有足够的疏水性，可以通过低沸点醋酸盐萃取和简易蒸馏从硫酸水溶液中高效分离。提出了一种催化方法来简化这一步骤。然而，新的挑战是目前可用的HDO催化剂不足以处理未精制的LA。Heyden和Bond建议采用计算和实验相结合的方法，从根本上了解在Ru/C和RuRe/C催化剂上，在水溶液和稀硫酸溶液中，LA的温和、多相催化加氢脱氧为GVL的反应机理，从而发现潜在的改进催化剂，从而使整个策略更具工业意义。本课题的基本目的是为合理设计具有优良活性、选择性和稳定性的新型多相催化剂，为硫酸水溶液中LA - GVL的HDO反应提供科学依据。一个成功的结果与木质纤维素生物质的水相处理广泛相关。此外，计算和实验相结合的研究方法的成功表明，这种策略不仅增加了我们对反应机制的理解，而且减少了设计新的非均相催化剂所需的时间和财力，以满足资源有限的世界不断变化的需求。参与该项目的博士生将成为计算催化与实验催化实践和结合的专家。此外，研究成果将被纳入南卡罗莱纳大学海登教授的“多尺度建模：从电子到化学反应器”和锡拉丘兹大学邦德教授的“多相催化”选修课中。

The modern petrochemical industry has achieved impressive efficiencies in meeting societaldemands through selective transformations of a few, key building block chemicals. A future self-sustaining biorefining industry will similarly be based on a selected platform of renewable building blocks which may yield transportation fuels or commodity and specialty chemicals. A recent study has identified 10 promising biomass derivatives that have the potential to serve as building blocks for future bio-refineries. Of those, Levulinic Acid (LA) is particularly promising as it can be produced inexpensively and in high yields by sulfuric acid hydrolysis of a variety of lignocellulosic feedstocks. Conversion processes of LA to fuel additives, chemicals, and monomers for plastics and textiles have been demonstrated, but not commercialized. A derived chemical, ?×-valerolactone (GVL), is a promising and extremely flexible intermediate, from which these same numerous desirable end-products can be obtained. Despite a myriad of applications for GVL, its large scale production is not yet established, owing largely to difficulties associated with the purification of its immediate precursor, LA.Professor Andreas Heyden from the University of South Carolina and Professor Jesse Q. Bond from Syracuse University believe these issues have solutions, and have received this NSF award to establish the underlying science that can make feasible the production of the lignocellulosic biomass-derived platform chemical GVL on a commercial scale. In the present state of the art, LA must undergo a costly purification scheme to remove residual sulfuric acid from cellulose hydrolysis prior to conversion to GVL. H2SO4 must be recovered and recycled, in line with a commitment to the long term sustainability of biorefining processes. GVL is sufficiently hydrophobic to allow an energy efficient separation from aqueous sulfuric acid by extraction with a low-boiling acetate followed by facile distillation. A catalytic approach to streamline this step has been proposed. However, the new challenge is the inadequacy of presently available HDO catalysts for processing of unrefined LA. Heyden and Bond propose to use a combined computational and experimental approach to obtain fundamental understanding of the reaction mechanism of the mild, heterogeneously catalyzed hydrodeoxygenation of LA to GVL over Ru/C and RuRe/C catalysts in both aqueous and dilute sulfuric acid solutions, leading to potential improved catalysts and thus making the entire strategy more industrially relevant.The fundamental objective of this project is to create a scientific basis for the rational design of novel heterogeneous catalysts with superior activity, selectivity, and stability for the HDO of LA to GVL in aqueous sulfuric acid. A successful outcome is broadly relevant in aqueous phase processing of lignocellulosic biomass. Further, success of the combined computational and experimental research approach illustrates that such a strategy not only increases our understanding of reaction mechanisms, but also reduces the time and financial resources needed for the design of new heterogeneous catalysts tailored to meet the changing needs of a world with limited resources. The PhD students involved in this project will become experts in the practice and integration of computational and experimental catalysis. Also, the research results will be incorporated into the elective classes ¡§Multiscale Modeling: From Electrons to Chemical Reactors¡¨ being taught by Heyden at the University of South Carolina and ¡§Heterogeneous Catalysis¡¨ being offered by Bond at Syracuse University.