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

现代石化工业通过有选择地改造几种关键的积木化学品，在满足社会需求方面取得了令人印象深刻的效率。未来自给自足的生物精炼行业将同样以可再生建筑材料的选定平台为基础，这些可再生建筑材料可能会生产运输燃料或商品和特种化学品。最近的一项研究确定了10种前景看好的生物质衍生品，它们有可能成为未来生物炼油厂的基石。其中，乙酰丙酸(LA)尤其有希望，因为它可以通过各种木质纤维原料的硫酸水解来廉价和高产率地生产。LA转化为燃料添加剂、化学品以及塑料和纺织品的单体的过程已经得到演示，但尚未商业化。一种衍生的化学物质，？×-戊内酯(GVL)，是一种很有前途的非常灵活的中间体，从它可以得到同样多的期望的最终产品。尽管GVL有无数的应用，但其大规模生产尚未建立，主要是由于与其直接前体LA的提纯有关的困难。南卡罗来纳大学的Andreas Heyden教授和锡拉丘兹大学的Jesse Q.Bond教授相信这些问题都有解决方案，并获得了NSF奖，以建立使木质纤维生物质衍生平台化学品GVL能够商业规模生产的基础科学。在目前的技术状态下，在转化为GVL之前，LA必须经历昂贵的纯化方案来从纤维素水解中去除残留的硫酸。必须回收和再循环硫酸，以符合对生物精炼过程长期可持续性的承诺。GVL具有足够的疏水性，可以通过低沸点的醋酸盐提取然后简单的蒸馏来从含水的硫酸中高效地分离出来。已经提出了一种简化这一步骤的催化方法。然而，新的挑战是目前可用的用于加工未精制LA的HDO催化剂的不足。Heyden和Bond建议使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LA在水溶液和稀硫酸溶液中温和、多相催化加氢脱氧制GVL的反应机理，从而获得潜在的改进催化剂，从而使整个策略更具工业意义。本项目的基本目标是为合理设计具有优异活性、选择性和稳定性的新型多相催化剂提供科学依据。一项成功的结果在木质纤维生物质的水相加工中具有广泛的意义。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理的理解，而且减少了设计新的多相催化剂所需的时间和财政资源，以满足资源有限的世界不断变化的需求。参与这个项目的博士生将成为计算催化和实验催化的实践和集成方面的专家。此外，研究成果将被纳入由海登在南卡罗来纳大学讲授的选修课《多尺度建模：从电子到化学反应》和由邦德在锡拉丘兹大学讲授的《多相催化》。

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.