Hydrogen Free Selective Hydrogenation: Step Changing Innovation in Catalysis by Gold

该项目提出了雄心勃勃的目标，即在连续流程操作中实现原子效率和增强催化活性的“无氢”加氢。这项工作汇集了两个在多相催化剂制备、表征和反应工程(Heriot-Watt大学化学工程基恩)和催化表面科学(Baddeley化学，圣安德鲁斯大学)方面具有专业知识的成熟研究小组。这种协作所产生的协同效应使我们能够在催化剂设计和优化方面进行创新，将基础和现场表面科学测量整合到催化剂的合成/表征和测试中。以前的工作已经在负载型Au催化剂上建立了硝基和羰基还原的超选择性。然而，由于氢在Au上解离吸附的活化能垒，反应速率略低于标准的非选择性金属催化剂(铂、钯和镍)。金促进的氢化反应是在仍未反应的过量氢气中进行的，导致基本过程效率低下和不可持续。我们提出了一种创新的催化脱氢(作为反应氢的来源)与氢化的耦合。初步数据为在氧化物负载的金和铜的物理混合物上将2-丁醇脱氢与糠醛加氢(制得糠醇)耦合的概念提供了证据。与单组分金催化剂相比，我们记录了耦合体系中氢气利用率(数量级)的提高和选择性加氢速率的提高。糠醛是一种生物质衍生的杂环醛，可作为非石油基可再生原料。目标糠醇产品是一种高价值的化学品，用于制造树脂/橡胶/粘合剂，并用作药物合成的化学构件。我们提出的偶联反应是阶跃变化的，就未反应氢而言，缩小了可持续性差距。由于Au实际上“借用”了通过铜促进脱氢原位产生的氢气，耦合体系绕过了压缩氢气的使用，这对大规模化学生产具有重要的安全意义。我们已着手通过一系列表面科学测量项目来获得对耦合脱氢/氢化反应的基本了解，这些测量包括STM、RAIRS、XPS、TPD和DRIFT分析，这些测量将提供关于反应物/产品表面相互作用的关键信息。这项工作将首先集中在负载金和铜物理混合物上的反应耦合，解决对金属颗粒大小和电子性质的敏感性，金属/载体界面的作用，氢溢出，传输和反应性。表面科学方法提供的分子水平的机理理解，再加上气相物种对表面组成(MEI)的影响的确定，将有助于合成负载型双金属(Au-Cu)，并制定合理的催化剂设计方案，以实现提供最佳氢利用效率的催化剂配方。与先正达和英国萨索尔科技公司作为工业合作伙伴的合作将确保这项工作产生真正的商业影响。最终的成果是一种催化过程，能够在可再生呋喃平台反应物的可持续无氢加氢反应中以更高的速度提供100%的选择性。这一建议非常符合EPSRC的塑造能力议程，特别是支持“能源效率”、“可持续性”和“前沿制造”优先事项的“催化”主题。此外，这项工作还针对“Dial-a-分子-100%高效合成”这一重大挑战，制定了针对“100%高效合成的催化范例”主题的工作方案。

This project sets out the ambitious goal of achieving atom efficiency and enhanced catalytic activity in "hydrogen free" hydrogenation in continuous flow operation. The work brings together two established research groups with expertise in heterogeneous catalyst preparation, characterisation and reaction engineering (Keane, Chemical Engineering, Heriot-Watt University) and catalytic surface science (Baddeley, Chemistry, St. Andrews University). The synergy that results from this collaboration allows innovation with respect to catalyst design and optimisation with the integration of fundamental and in situ surface science measurements into catalyst synthesis/characterisation and testing. Prior work has established ultra-selectivity in nitro- and carbonyl- group reduction over supported Au catalysts. However, reaction rates were appreciably lower than standard non-selective (Pt, Pd and Ni) metal catalysts due to the activation energy barrier for H2 dissociative adsorption on Au. Gold promoted hydrogenation is conducted in excess H2 that remains unreacted, resulting in fundamental process inefficiency and unsustainability. We propose an innovative coupling of catalytic dehydrogenation (as a source of reactive hydrogen) with hydrogenation. Preliminary data provide proof of concept for the coupling of 2-butanol dehydrogenation with furfural hydrogenation (to furfuryl alcohol) over physical mixtures of oxide supported Au and Cu. We have recorded (orders of magnitude) enhanced H2 utilisation in the coupled system and elevated selective hydrogenation rate relative to the single component Au catalyst. Furfural is a biomass derived heterocyclic aldehyde that can serve as a non-petroleum based renewable feedstock. The target furfuryl alcohol product is a high value chemical used to manufacture resins/rubbers/adhesives and as a chemical building block for drug synthesis. Our proposed coupling reaction is step changing and closes the sustainability gap in terms of unreacted hydrogen. As Au in effect 'borrows' hydrogen generated in situ via Cu promoted dehydrogenation, the coupled system circumvents the use of compressed H2, which has important safety implications for large scale chemical production.We have set out to gain a fundamental understanding of coupled dehydrogenation/ hydrogenation through a programme of surface science measurements involving STM, RAIRS, XPS, TPD and DRIFTS analysis that will provide critical information on reactant/product surface interactions. The work will first focus on reaction coupling over supported Au and Cu physical mixtures, addressing sensitivity to metal particle size and electronic character, the role of the metal/support interface, hydrogen spillover, transport and reactivity. The molecular-level mechanistic understanding provided by the surface science methodologies coupled with a determination of the influence of the gas phase species on surface composition (MEIS) will inform synthesis of supported bimetallics (Au-Cu) with a programme of rational catalyst design directed at achieving the catalyst formulation that delivers the optimum hydrogen utilisation efficiency. Collaboration with Syngenta and Sasol Technology UK as industrial partners will ensure that the work delivers real commercial impact. The ultimate deliverable is a catalytic process than can deliver 100% selectivity at elevated rates in the sustainable hydrogen free hydrogenation of renewable furfuran platform reactants.This proposal fits well with the EPSRC shaping capability agenda, notably the "catalysis" theme, underpinning "energy efficiency", "sustainability" and "frontier manufacturing" priorities. Moreover, the work tackles head on the "Dial-a-Molecule-100% Efficient Synthesis" Grand Challenge with a programme of work directed at the "catalytic paradigms for 100% efficient synthesis" theme.