Tuning Catalyst Surfaces to Control Aldol Reactions in Biomass Conversion

石油是世界上最重要的能源，约占35%的一次能源消耗和大部分的化工原料；应对当前的世界能源危机被认为是发达国家和发展中国家的首要任务，为了应对日益减少的世界石油储量和日益增长的全球气候变化对环境的担忧，迫切需要可持续的化学品和燃料来源。来自生物质的可持续“碳中性”能源可以在实现这一目标方面发挥重要作用，预测表明每年温室气体排放量可减少高达12.4亿吨。运输燃料可以由生物油生产，生物油很容易从可持续的生物质资源中获得，如废弃的农作物、林业产品、高产的不可食用植物，如柳枝稷，然而，生物油不能直接用作运输燃料，在使用前需要催化升级。同样，美国能源部确定了12种“平台化学品”，可以通过木质纤维素生物质的化学或生化转化直接从糖中生产，并为可持续化学品制造提供基本原料。这些分子是高度含氧的，并含有一系列理想的官能团，如酸、醇、合成材料中经常需要的羧基。因此，与目前从石油开始的化学合成（需要插入氧气来生成功能材料）不同，生物质衍生的构建模块需要新技术来选择性地异构化和/或“脱氧”这些高功能分子以达到目标分子。催化在促进节能选择性分子转化方面有着丰富的历史，并为90%的化学制造过程和20%以上的工业产品做出了贡献。在后石油时代，催化将是克服经济上可行的生物燃料和化学品路线的工程和科学障碍的核心。该提案将解决选择性地将糖转化为平台化学品或燃料以及将生物油转化为燃料的主要技术挑战；这两种反应都涉及到共同的反应，即缩合和脱氧反应的结合，以产生烷烃。目前的商业催化剂不是为这种应用而设计的，并且具有固有的不良寿命和选择性。我们研究的具体目标将是通过材料设计的组合（在卡迪夫）来提高催化剂的选择性和效率，以创建包含相互连接的宏观和介孔的受控孔隙结构，专门用于减少生物质常见的大块和粘性原料的扩散限制。材料的设计将以工作催化剂（在俄克拉何马州）的现场光谱分析为指导，这将使我们能够确定导致性能提高的关键特征，从而使活性部位的性质得到相应的调整。这些样品将在液体（卡迪夫）和气相（诺曼）条件下在两个实验室进行测试。我们将利用获得的知识来设计改进的醇缩合固体催化剂，这对生物质转化为化学品和燃料至关重要。因此，拟议的研究涉及国家和全球对可持续性的需要。

Oil is the most important source of energy worldwide, accounting for some 35% of primary energy consumption and the majority of the chemical feedstocks; tackling the current world energy crisis is recognised as a top priority for both developed and developing nations, with sustainable sources of chemicals and fuels urgently sought in response to both diminishing world oil reserves and increasing environmental concerns over global climate change. Sustainable 'carbon-neutral' energy sources derived from biomass can play a major role in achieving this goal, with projections suggesting annual greenhouse gas emissions could be reduced by up to 12.4 Gtons. Transportation fuels can be generated from bio-oils which are readily obtained from sustainable biomass resources such as waste agricultural crops, forestry products, high yielding inedible plants such as Switchgrass, however, bio-oils cannot be used directly as transportation fuels and require catalytic upgrading before use. Likewise the US Department of Energy identified 12 'Platform Chemicals' that can be produced directly from sugars via chemical or biochemical transformation of lignocellulosic biomass and provide the basic feedstocks for sustainable chemicals manufacture. These molecules are highly oxygenated and contain a range of desirable functional groups such as acid, alcohol, carboxyl groups often required in synthetic materials. Thus in contrast to current chemicals synthesis starting from oil where oxygen insertion is required to generate functional materials, biomass derived building blocks necessitate new technology to selectively isomerise and/or 'deoxygenate' these highly functional molecules to reach the target molecule.Catalysis has a rich history of facilitating energy efficient selective molecular transformations and contributes to 90% of chemical manufacturing processes and to more than 20% of all industrial products. In a post-petroleum era catalysis will be central to overcoming the engineering and scientific barriers to economically feasible routes to bio-fuels and chemicals. This proposal will address the major technological challenge of selectively converting sugars to platform chemicals or fuels and bio-oil to fuels; both of which involve common reactions, namely a combination of condensation and deoxygenation reactions to produce alkanes. Current commercial catalysts are not designed for such applications and have inherently poor lifetimes and selectivity. The specific goal of our research will be to improve catalyst selectivity and efficiency via a combination of materials design (at Cardiff) to create controlled pore architectures containing interconnected macro- and mesopores specifically aimed to reduce diffusion limitation of bulky and viscous feedstocks common to biomass. The design of materials will be guided by in-situ spectroscopic analysis of working catalysts (at Oklahoma) which will allow us to identify key features that lead to improved performance and thus allow the nature of the active site to be tailored accordingly. These samples will be tested in both laboratories under liquid (Cardiff) and vapor phase (Norman) conditions. We will use the acquired knowledge to design improved solid catalysts for aldol condensations, which are crucial for the conversion of biomass to chemicals and fuels. The proposed research thus addresses national and global needs for sustainability.