Functional bionanomaterials and novel processing for targeted catalytic applications

用于目标催化应用的功能性生物纳米材料和新颖加工

• 批准号: EP/D057310/1
• 负责人: Gerrit Van Der Laan
• 金额: $ 17.78万
• 依托单位: Science and Technology Facilities Council
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2007
• 资助国家: 英国
• 起止时间: 2007 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FD057310%2F1
• 关键词: Functional; bionanomaterials; novel; processing; targeted

Commercial catalysts are often based on metallic nanoparticles which have unusual and highly reactive properties due to their high proportion of surface atoms as compared to buried ones. Catalytic reactions occur at or just below surfaces and are helped by the crystal surface having defect sites and kinks. The exact architecture of the kinks can help in molecular recognition between the catalyst and its substrate, and help to make a particular form of the product molecule (called an enantiomer) over its mirror image 'twin'. Industry needs enantiomeric selectivity, and also better ways to make C-C bonds; both would become possible using a new type of nanoparticle based on bacteria. It is difficult to make nanoparticles chemically as they want to aggregate. When this happens the special properties are lost. Usually 'helper' chemicals ('passivant ligands') are needed. Bacteria can overcome this need. They can biomanufacture nanoparticles using enzymes and also support the nanoparticles by providing their own passivants. The catalytic bionanoparticles can be employed as catalysts by using the metallised bacteria as small (~2 microns) bodies in suspension (they can be recovered using a magnet), or by growing them first as a biofilm on (e.g) beads or monoliths and then metallising to form a catalytic nano-coating. Nothing is known yet about the surface structures of the bionanocrystals but they are excellent catalysts. It is known elsewhere that the application of dielectric fields (such as microwaves) can alter crystal surfaces (to make new, or different defects and kinks) or align crystals so that their most active faces point outwards. Nobody has applied dielectric fields to manipulate catalytic nanoparticles, especially not BIOnanoparticles, and we hope to make a completely new class of materials(superbionanocatalysts). We will test these in 4 important reactions where there are strong industrial needs: (a) enrich for a particular product in a mixture; (b) do a reaction which specifically needs NANOparticles; (c) do a reaction where we want an enantiomeric selection; (d) do a reaction which underpins commercial fertiliser production worldwide but usually needs very high temperatures and pressures. (a-c)usually use precious metal catalysts and (d) uses a catalyst based on iron; in the nanoworld these can often be used interchangeably (or together) because the same atomic-scale processes are involved. Effects of this are seen in magnetic (as well as catalytic) properties (a very useful diagnostic probe), while another facet is unravelled via an electrochemical 'dialogue' between the nanocrystal and the experimenter. These become even more interesting when the bacteria make 'bimetallics' (combining 2 metals); these often have greatly enhanced properties. We will look at bio-bimetallics for catalysis and also as fuel cell catalysts to make clean energy. Reactions involving Fe catalysts are special. They depend on the exact type of Fe used (the mineral phase); bacteria can make specific mineral phases to order. The catalytic reaction uses an activated form of hydrogen which normally only happens at high temperatures; small particles of ferric oxide are partially reduced by the active H to give some Fe metal (the catalyst; detected magnetically). Dielectric processing can also activate H, but at a much lower temperature, saving energy. Commercially, H is made from 'cracking' natural gas but this H contains traces of catalyst poisons. Biologically-made H is poison-free and the use of Bio-H will also help to extend catalyst life. We will make new, robust, superior, catalytic materials but, importantly, we will also relate the new crystal and nano structures to improved functions, applying a full range of solid state analytical methods to complement the magnetic and electrochemical ones. By understanding pivotal molecular processes in the nanoworld we can then design better catalysts for other commercial applications too.

商业催化剂通常基于金属纳米颗粒，其具有不寻常的和高反应性的性质，这是由于其表面原子的比例高于掩埋的原子。催化反应发生在表面处或表面之下，并得到具有缺陷位点和扭结的晶体表面的帮助。扭结的确切结构可以帮助催化剂和其底物之间的分子识别，并有助于在其镜像“孪生”上形成特定形式的产物分子（称为对映异构体）。工业需要对映体选择性，也需要更好的方法来制造C-C键;使用基于细菌的新型纳米颗粒，这两者都将成为可能。由于纳米颗粒想要聚集，所以很难用化学方法制造纳米颗粒。当这种情况发生时，特殊属性就会丢失。通常需要“辅助”化学品（“钝化配体”）。细菌可以克服这种需要。它们可以使用酶来生物制造纳米颗粒，也可以通过提供自己的钝化剂来支持纳米颗粒。催化生物纳米颗粒可以通过使用金属化细菌作为悬浮液中的小（~2微米）体（它们可以使用磁体回收）或通过首先使它们作为生物膜在（例如）珠或整料上生长，然后金属化以形成催化纳米涂层来用作催化剂。目前还不知道生物纳米晶体的表面结构，但它们是极好的催化剂。在其他地方已知，介电场（如微波）的应用可以改变晶体表面（以产生新的或不同的缺陷和扭结）或排列晶体，使其最活跃的面指向外面。没有人应用介电场来操纵催化纳米颗粒，尤其是生物纳米颗粒，我们希望制造一种全新的材料（超级生物纳米催化剂）。我们将在有强烈工业需求的4个重要反应中测试这些：（a）在混合物中富集特定产品;（B）进行特别需要纳米颗粒的反应;（c）进行我们想要对映体选择的反应;（d）进行支撑全球商业肥料生产但通常需要非常高的温度和压力的反应。（a-c）通常使用贵金属催化剂和（d）使用基于铁的催化剂;在当今世界，这些催化剂通常可以互换使用（或一起使用），因为涉及相同的原子级工艺。这种效应可以在磁性（以及催化）特性（一种非常有用的诊断探针）中看到，而另一个方面则通过实验者和实验者之间的电化学“对话”来揭示。当细菌制造“双金属”（结合2种金属）时，这些变得更加有趣;这些通常具有大大增强的特性。我们将着眼于生物双金属催化剂，也作为燃料电池催化剂，使清洁能源。涉及铁催化剂的反应是特殊的。它们取决于所使用的铁的确切类型（矿物相）;细菌可以按顺序制造特定的矿物相。催化反应使用通常仅在高温下发生的活化形式的氢;氧化铁的小颗粒被活性H部分还原以产生一些Fe金属（催化剂;磁性检测）。电介质处理也可以激活H，但在更低的温度下，节省能源。在商业上，H是由“裂解”天然气制成的，但这种H含有痕量的催化剂毒物。生物合成的H是无毒的，使用Bio-H也有助于延长催化剂的寿命。我们将制造新的、坚固的、上级的催化材料，但重要的是，我们还将把新的晶体和纳米结构与改进的功能联系起来，应用全方位的固态分析方法来补充磁性和电化学方法。通过了解世界上关键的分子过程，我们可以为其他商业应用设计更好的催化剂。