NSF-BSF: Steering Selectivity in Aldol Reactions by Control of Relative Effective Reaction Rates in Porous Catalysts

该项目由美国国家科学基金会（NSF）和美以双边国家科学基金会（BSF）合作机会NSF 17-520资助，重点研究通过减少化学废物使化学过程更加环保的催化作用。我们感兴趣的化学转变是醛醇缩合，它会在两个碳原子之间形成一个新的键。醛醇缩合是许多大宗、精细和特种化学品合成中必不可少的反应。这一反应显示了将生物质原料升级为燃料或化学品的希望。目标是引导这种化学反应，以提供所需的产品，而不会产生大量的副产物。方法是开发新的固体催化剂，并通过改变其表面化学成分和孔隙形态，调整其化学和物理性质以获得最佳性能。马萨诸塞大学阿默斯特分校和以色列理工学院的这项合作工作所产生的新知识和基本理解，将有助于更好地指导醛缩和其他类似的复杂和关键的化学反应。此外，该项目将有助于提高美国在生物可再生产品化学制造方面的竞争力，并将促进培训熟练掌握生物质加工的多样化劳动力。醛醇反应包括两个连续的步骤，加成和随后的脱水。交叉醛缩，特别是那些涉及不对称酮，可以导致大量的初级和次级产物。该项目的中心假设是，醛醇反应的选择性是由相对有效反应速率控制的，可以通过调整活性表面位点和有效因子来调节。虽然在平行和顺序反应中，输运限制对选择性影响的理论很早以前就有了概述，但在复杂的液相反应中很少实现这些概念。本研究项目通过控制催化剂的表面化学和孔隙结构，严格测试了这些概念的实际可行性。主要的催化剂平台是层状双氢氧化物，因为它们允许化学和物理性质的广泛而独立的变化；也就是说，可以定制酸碱和孔隙特征。多孔模型材料用于独立研究运输限制。反应物的复杂性和反应条件是不同的，以确保广泛的有效性的发现。该项目受益于美国机构和以色列理工学院的互补专业知识和仪器能力。学生培训将包括参观合作伙伴实验室和相关学科的研究生课程。通过适当的征聘努力和针对女高中生的外联活动，力求扩大妇女对科学的参与。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project, funded under the National Science Foundation (NSF) and US-Israel Binational Science Foundation (BSF) collaborative opportunity NSF 17-520, focuses on the study of catalysis to make chemical processes more environmentally friendly by reducing chemical waste. The chemical transformation of interest is the aldol condensation, which results in a new bond between two carbon atoms. Aldol condensation is an essential reaction in many syntheses of bulk, fine, and specialty chemicals. This reaction shows promise for upgrading biomass-derived feedstocks to fuels or chemicals. The objective is to steer this chemical reaction to give the desired product without generating a multitude of side products. The approach is to develop new solid catalysts and, by varying their surface chemical composition and pore morphology, tune their chemical and physical properties for optimal performance. The new knowledge and fundamental understanding emerging from this collaborative work between the University of Massachusetts Amherst and the Technion-Israel Institute of Technology will serve to better direct aldol condensations and other similarly complex and pivotal chemical reactions. In addition, the project will contribute to U.S. competitiveness in chemical manufacturing of biorenewable products and will promote training of a diverse workforce skilled in biomass processing. Aldol reactions consist of two sequential steps, addition and subsequent dehydration. Cross aldol condensations, particularly those involving unsymmetrical ketones, can lead to a multitude of primary and secondary products. The central hypothesis of this project is that selectivity in aldol reactions, which is governed by relative effective reaction rates, can be tuned by tailoring the active surface sites and effectiveness factors. While theory on the influence of transport limitations on the selectivity in parallel and sequential reactions has been outlined long ago, there are few realizations of these concepts in complex liquid phase reactions. This research project rigorously tests the practical viability of these concepts by manipulating surface chemistry and pore structure of the catalysts. The main catalyst platform is layered double hydroxides, because they allow for a wide and independent variation of chemical and physical properties; that is, acid-base and pore characteristics can be tailored. Porous model materials serve to independently investigate transport limitations. Reactant complexity and reaction conditions are varied to ensure broad validity of the findings. The project benefits from complementary expertise and instrumental capability at the U.S. institution and at Technion in Israel. Student training will include visits of the partner laboratory and a subject-relevant graduate course. The participation of women in science is sought to be broadened through appropriate recruiting efforts and outreach activities targeting female high school students.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.