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Computational studies of supercritical fluids

超临界流体的计算研究

基本信息

批准号：
EP/E06082X/1
负责人：
Richard Wheatley
金额：
$ 48.08万
依托单位：
University of Nottingham
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%2FE06082X%2F1
关键词：
Computational studies supercritical fluids

项目摘要

Supercritical carbon dioxide is an exciting solvent for chemical reactions. It is cheap, non-toxic, non-flammable and non-polluting, and its physical properties are greatly influenced by relatively small variations in temperature and pressure, which enable the reaction outcomes to be controlled. However, fewer chemicals are soluble in carbon dioxide than in solvents such as water, which restricts the use of supercritical carbon dioxide in chemical processes.To increase the solubility of organic molecules in carbon dioxide, hydrogen atoms in hydrocarbon chains can be replaced by fluorine atoms. Alternatively, fluorinated hydrocarbon molecules (HFCs) can be used as the basis of surfactants, which enable small droplets of water to exist within the carbon dioxide solvent. Chemical reactions can then take place inside the water droplets, even when the chemicals involved are not soluble in the surrounding carbon dioxide.Fluorinated molecules can have a low environmental impact, and a number of small HFCs have replaced ozone-depleting CFCs as refrigerants. Unfortunately, the high cost of producing larger fluorinated molecules has limited the commercial potential of HFC / carbon dioxide mixtures. Furthermore, the reason for the enhanced solubility of fluorinated molecules in carbon dioxide is not known, which makes it difficult to design more cost-effective alternatives to HFCs.The proposed research will tackle these theoretical and practical problems associated with HFC / carbon dioxide mixtures. The work will be carried out at the University of Nottingham, and is a new collaboration between established research groups with considerable expertise in the areas of molecular interactions (Wheatley), simulations (Hirst) and experimental measurements on supercritical carbon dioxide (Poliakoff and Ke).We shall begin by developing new computational methods, based on those already used successfully by the PI, to investigate the interactions between HFCs and carbon dioxide molecules with more accuracy and in more detail than previously possible. Experimental measurements of the phase equilibria, critical phenomena and thermodynamic properties of the mixtures, using state-of-the-art equipment developed by the experimental CoIs, will allow validation and improvement of these computational methods for mixtures involving small HFCs, and for the few large HFCs that are currently available.The calculated intermolecular interactions will be used in atomic simulations of the structures and physical properties of HFC / carbon dioxide mixtures. Hirst's experience of simulations of large organic molecules will ensure that the technical challenges of this work are overcome, and the demand that the simulations will place on computing resources will be met by the new 1024-node teraflop computing cluster at the University. The results obtained from these simulations will allow us to explore the reason for the enhancement of solubility by fluorination, and to produce new solubility data - which cannot currently be obtained from experiment - for a range of new HFC molecules. In the longer term, the research will allow us to predict the characteristics that make molecules soluble in supercritical carbon dioxide, and will therefore assist in the design of new, efficient, environmentally-friendly chemical solvents.

超临界二氧化碳是一种令人兴奋的化学反应溶剂。它价格便宜，无毒，不易燃，无污染，其物理性能受温度和压力相对较小的变化的影响很大，这使得反应结果可以控制。然而，溶解在二氧化碳中的化学物质比溶解在水等溶剂中的化学物质要少，这限制了超临界二氧化碳在化学过程中的使用。为了增加有机分子在二氧化碳中的溶解度，碳氢化合物链中的氢原子可以被氟原子取代。或者，氟化碳氢化合物分子（hfc）可用作表面活性剂的基础，使小水滴能够存在于二氧化碳溶剂中。然后，化学反应可以在水滴内部发生，即使所涉及的化学物质不能溶于周围的二氧化碳。氟化分子对环境的影响很小，许多小的氢氟碳化物已经取代了消耗臭氧层的氟氯碳化物作为制冷剂。不幸的是，生产较大的氟化分子的高成本限制了氢氟烃/二氧化碳混合物的商业潜力。此外，氟化分子在二氧化碳中的溶解度增强的原因尚不清楚，因此很难设计出更具成本效益的氢氟碳化物替代品。拟议的研究将解决这些与氢氟烃/二氧化碳混合物相关的理论和实践问题。这项工作将在诺丁汉大学进行，并且是在分子相互作用（Wheatley），模拟（Hirst）和超临界二氧化碳实验测量（Poliakoff和Ke）领域具有相当专业知识的成熟研究小组之间的新合作。我们将首先在PI已经成功使用的计算方法的基础上开发新的计算方法，以比以前更精确和更详细地研究氢氟碳化物和二氧化碳分子之间的相互作用。使用实验coi开发的最先进设备对混合物的相平衡、临界现象和热力学性质进行实验测量，将允许验证和改进这些计算方法，用于涉及小型氢氟碳化物的混合物，以及目前可用的少数大型氢氟碳化物。计算的分子间相互作用将用于氢氟烃/二氧化碳混合物的结构和物理性质的原子模拟。赫斯特在模拟大型有机分子方面的经验将确保这项工作的技术挑战得到克服，而模拟对计算资源的需求将由该大学新的1024节点teraflop计算集群来满足。从这些模拟中获得的结果将使我们能够探索氟化增强溶解度的原因，并为一系列新的HFC分子提供目前无法从实验中获得的新的溶解度数据。从长远来看，这项研究将使我们能够预测使分子可溶于超临界二氧化碳的特性，并因此有助于设计新的、高效的、环保的化学溶剂。