浅谈21世纪的化学工程

在参考我国化工界已有战略研究的基础上,进一步分析了当前我国社会经济发展需求和世界科技发展的趋势,指出我国化学工程科学正面临难得的发展机遇,同时也面临多方位的挑战。化学工程作为一个共性的工程学科,既要适应其应用领域的扩展,更要充分利用科学技术发展带来的机遇,扩展深化自身的知识基础,为各种物质转化相关领域提供共性的理论、方法和技术。复杂系统理论的发展、计算技术的进步以及测试技术的提升,为化学工程科学的发展提供了新的动力;经济社会的进步,能源、资源与环境问题的突显以及高技术的发展,大大扩展了化学工程服务的领域。我们应当抓住这一机遇,适应这一变化,为解决能源、资源和环境等领域的瓶颈问题,推动高技术的发展做出贡献,开创化学工程新的发展阶段。     

分子化学工程学——一门新兴的学科

分子化学工程学是利用分子科学、分子工程的成就和研究方法、手段来探求化学工程中的规律,逐步形成的一门新兴的工程技术类学科。它利用超高速电子计算机技术,从分子·原子尺度进行材料的分子设计和合成及工艺设计。以更有效地指导工业生产和发展化学工程学。     

材料化学工程科学内涵及方法初探:从介观尺度界面流体行为出发认知材料

作为一门新兴的交叉学科,材料化学工程科学内涵的进一步凝练和方法论的建立显得十分重要和迫切。介观尺度下界面流体的研究对于材料化学工程具有重要意义,材料化学工程的科学内涵在于通过认识介观尺度下界面处流体行为来"认知"材料,以期建立材料结构、性能(应用)与制备(生产)三者之间的关系。其中,弄清介观尺度下复杂作用和复杂结构对界面流体行为的影响,是"认知"材料的关键。分子模拟技术作为单因素遴选介观尺度各影响因素的有效手段,在实际应用中存在两大难点:如何同时获得界面流体反应和传递两个方面的信息;如何实现分子层面认识在材料应用层面的转化。基于此,初步讨论了材料化学工程研究方法的发展趋势。     

化学科学的研究新领域——超分子化学

介绍超分子化学的基本概念,阐述超分子体系中分子间弱相互作用、分子识别、分子组装和几种组装体的形态,并指出了超分子化学对科学理论研究的重要意义和广阔的应用前景。     

马脊梁镜煤有机质大分子模型构建及分子模拟

运用工业分析、元素分析及¹³C核磁共振波谱、X射线光电子能谱和傅里叶变换红外光谱分析,构建了马脊梁镜煤有机质大分子结构模型。在该结构模型中,芳环桥碳与周碳之比为0.24,芳环的类型以蒽、萘为主;脂肪碳原子主要是甲基、亚甲基和次甲基,氧接脂碳含量最少;每个大分子平均含氧原子22个,氧原子存在于酚羟基、羰基、羧基和醚氧中,个数分别为9、4、3和3;氮原子以一个吡啶和一个吡咯的方式存在。该结构模型的平均分子式为C₂₂₂H₁₆₈O₂₂N₂,分子量为3212。对所建分子模型分别进行了核磁共振碳谱、红外光谱及密度的模拟计算,并与测试结果进行对比验证。结果表明,所建模型能够较好地反映马脊梁镜煤有机质的大分子结构特征。     

药物分子设计前沿技术融入药物化学实验教学——基于分子对接技术的抑制PERK的活性化合物筛选实验

药物化学是一门实践性较强的课程,药物分子设计的快速发展,对于药物化学的实践学习具有非常重要的指导作用。因此,我们设计了一个基于分子对接技术的抑制蛋白激酶R样内质网激酶(protein kinase R-like ER kinase, PERK)活性化合物的虚拟筛选实验。该实验可以帮助学生掌握分子对接技术的基本原理,熟悉分子对接技术筛选活性化合物的基本操作方法,并学会药物分子设计相关专业软件的使用及实验数据的分析。通过具体的实践练习,使学生了解药物设计前沿技术,提升学生从事药物研发的素养。     

分子尺度的复杂反应体系动力学模拟(Ⅰ) 原料分子的Monte Carlo模拟

以DCC I工艺的工业常规分析数据为基础 ,采用MonteCarlo模拟和结构导向集总相结合的方法在分子尺度上对复杂反应体系的动力学进行研究 .主要介绍了如何将原料转化为 10 0 0个分子 ,每个分子又以 19个特征表示的原料分子的MonteCarlo模拟 .结果表明生成的分子能很好地反映原料的特性 ,对原料性质的预测值和标定数据吻合得较好     

催化裂解过程分子尺度反应动力学模型研究

以工业数据为基础,运用结构导向集总方法来构造烃分子,对催化裂解原料油进行了分子尺度上的Monte Carlo模拟.在深入研究催化裂解反应机理的基础上,以原料油模拟产生的分子矩阵作为反应物分子,将结构导向集总方法与Monte Carlo方法相结合,建立了催化裂解过程分子尺度的反应动力学模型.结果表明:Monte Carlo方法可以在分子尺度上实现对催化裂解原料较好的模拟,产品产率和汽油组成与实际值能较好地拟合.且随着虚拟分子数的增加,对原料油性质和反应结果的模拟计算精度提高;模型具有较好的适应性和外推性.     

分子尺度的复杂反应体系动力学模拟（Ⅰ）原料分子的Monte Carlo模拟

以DCC-I工艺的工业常规分析数据为基础,采用Monte Carlo模拟和结构导向集总相结合的方法在分子尺度上对复杂反应体系的动力学进行研究.主要介绍了如何将原料转化为1000个分子,每个分子又以19个特征表示的原料分子的Monte Carlo模拟.结果表明生成的分子能很好地反映原料的特性,对原料性质的预测值和标定数据吻合得较好.     

宁东红石湾煤大分子模型构建及量子化学计算

使用工业分析、元素分析、固体核磁（¹³C NMR）、X射线光电子能谱（XPS）、傅里叶变换红外光谱（FT-IR）对宁东红石湾（HSW）煤样进行表征,获得煤样中元素赋存的种类、价态、化学键环境等物质微观结构的关键参数。结果表明HSW煤结构以芳香族为主,占75.96%,桥接芳碳与周碳比为0.315,可知其结构中以萘为主,苯和蒽为辅。氧原子主要以醚氧基（C-O）、羰基（C=O）和羧基（-COO）的形式存在,其中C-O占53.57%。氮原子以吡啶和吡咯的形式存在。苯环的连接方式以三、四取代为主,分别占47.77%、32.97%,脂肪族中环烷烃或脂肪烃-CH₃占优势。确定HSW煤的分子式为C₂₂₁H₁₄₈O₂₈N₂,分子量为3142.32。在此基础上结合计算机辅助实现了二维和三维大分子模型构筑。应用量子化学计算对HSW煤大分子模型进行了优化及核磁共振、红外光谱模拟,验证了所建模型的合理性。最终实现了HSW煤的微观分子结构的实验与量子化学描述。     

分子模拟在化工应用中的若干问题及思考

随着高技术学科的飞速进步,化工学科在多年来已形成的理论和实验研究之外,又产生了一种完全独立而新颖的研究手段——分子模拟.目前化学工业受关注的新技术涉及聚合物、电解质等复杂物质,临界、超临界等复杂状态,界面、膜、溶液等复杂现象.实现化学工业从产品到过程设计完全自动化,在这些方面除了准确的物性数据外,更要对各种复杂现象的机理有深刻了解.分子模拟被认为是实现这一目标的关键技术之一.本文以分子动力学为主,结合计算量子化学,对分子模拟在化工应用中的若干问题进行讨论.     

计算材料学与材料结构的层次

首先从系统论的角度指出材料系统是一个复杂系统 ,接着分析了材料结构的尺度和层次问题及其影响 ,并介绍了计算材料学的产生和发展 ,最后讨论了这些认识和进展所提供的启示。这些启示可能会对材料科学家和材料工程技术人员今后的工作有一定的参考价值和促进作用。     

应用分子模拟求取流体化学势的新途径

提出了分子模拟中求取流体化学势的新途径——参考试验粒子方法、通过适当选择参考试验粒子,避免了试验粒子的插入操作和计算,同时解决了移出粒子方法在Metropolis取样构型中难以得到正确结果的缺陷.应用该方法对ρσ~3=0.5和 0.65的硬球流体以及kT/ε=1.2时ρσ~3=0.65、0.70、0.80、0.90的Lennard-Jones流体的研究结果表明,该方法具有收敛快、计算量小和精度高的优点.     

INSECT OLFACTORY RECEPTORS: CONTRIBUTIONS OF MOLECULAR BIOLOGY TO CHEMICAL ECOLOGY

Our understanding of the molecular basis of chemical signal recognition in insects has been greatly expanded by the recent discovery of olfactory receptors (Ors). Since the discovery of the complete repertoire of Drosophila melanogaster Ors, candidate Ors have been identified from at least 12 insect species from four orders (Coleoptera, Lepidoptera, Diptera, and Hymenoptera), including species of economic or medical importance. Although all Ors share the same G-protein coupled receptor structure with seven transmembrane domains, they present poor sequence homologies within and between species, and have been identified mainly through genomic data analyses. To date, D. melanogaster remains the only insect species where Ors have been extensively studied, from expression pattern establishment to functional investigations. These studies have confirmed several observations made in vertebrates: one Or type is selectively expressed in a subtype of olfactory receptor neurons, and one olfactory neuron expresses only one type of Or. In addition, all olfactory neurons expressing one Or type converge to the same glomerulus in the antennal lobe. The olfactory mechanism, thus, appears to be conserved between insects and vertebrates. Although Or functional studies are in their initial stages in insects (mainly Drosophila), insects appear to be good models to establish fundamental concepts of olfaction with the development of powerful genetic, imaging, and behavioral tools. This new field of study will greatly contribute to the understanding of insect chemical communication mechanisms, particularly with agricultural pests and disease vectors, and could result in future strategies to reduce their negative effects.     

QM/MM through the 1990s: The First Twenty Years of Method Development and Applications

The 2013 Nobel Prize in Chemistry was awarded to the authors of the first two publications utilizing the concept of combined quantum mechanical and molecular mechanical (QM/MM) methods. In celebrating this great event in computational chemistry, we review the early development of combined QM/MM techniques and the associated events that took place through the mid-1990s. We also offer some prospects for the future development of quantum mechanical techniques for macromolecular systems.     

Integration of COSMO‐based methodologies into commercial process simulators: Separation and purification of reuterin

The conceptual design of a new process is developed via computer‐aided simulation for separating and purifying reuterin, an antimicrobial substance obtained by bacterial fermentation of glycerol, from its mixture with the nonfermented substrate, the main subproduct of the process (1,3‐propanediol) and water. The nondatabank components included in the simulations are created by using the structures derived from quantum mechanical calculations and the properties (molecular weight, normal boiling point, and mass density) estimated by COSMO‐RS method. The unknown remainder properties are estimated by the methods and models used by default in Aspen Plus (v7.3). The COSMOSAC property model, also implemented in Aspen Plus, is specified with the molecular volumes and sigma profiles obtained by COSMO‐RS. The properties (boiling temperatures, densities, VL equilibria, etc.) predicted for glycerol, 1,3‐propanediol, water, and their mixtures by COSMO‐based methods agree reasonably well with experimental reported values, whereas those obtained for reuterin derivatives are consistent with the behavior of amphoteric compounds having strong capabilities to interact attractively with hydrogen donor and acceptor groups all together. The process consists of a two‐stage distillation operation, the first of which removes the water and the second one separates reuterin as a 99.5 wt %‐pure bottom product. The second column operates at low pressure (ca. 40 kPa) to avoid thermal decomposition of reuterin (over 280°C) and guaranties 99.9% recovery of the desired product. Water removing offers different heat integration and energy‐saving opportunities considering that condenser pressure of the first column can be increased to ～15 bar preserving the thermal integrity of the reuterin. Dimensions of the equipments as well as capital and operating costs are evaluated. © 2012 American Institute of Chemical Engineers AIChE J, 2012     

Generic Construction of Kraus Operators: d-level Systems in a Thermal Bosonic Bath

The dynamical evolution of open systems can be conveniently expressed in the operator sum representation in terms of Kraus operators. Here we introduce an expression for the canonical Kraus representation in terms of the eigenstates |γ〉 and eigenvalues E_γ of the total Hamiltonian, thus making a stronger connection to the tools in chemistry. The method is exact, and hence valid for non-Markovian evolution of the system to all orders of the coupling to the bath. Significantly, it provides a starting point for developing approximate Kraus operators based upon perturbative approximations to |γ〉 and E_γ. As an example, the explicit form of these operators is derived for a d-level system interacting with a single-mode thermal bath.     

Capture of H2S from binary gas mixture by imidazolium‐based ionic liquids with nonfluorous anions: A theoretical study

Selective capture of H₂S from gas mixture is essential to reduce its undesirable high corrosiveness and toxicity. Ionic liquids have been proposed as a promising material, and there is a need to clarify the capture mechanisms and search for optimal combination of cation and anion for application. This work aims to elucidate the interactions between H₂S and nonfluorous imidazolium ionic liquids (NIILs) at a molecular level. The effects of hydroxyl group on the tail of alkyl chain, and combinations of imidazolium cations and nonfluorous anions on H₂S capture are explored using quantum chemistry calculations. Furthermore, molecular dynamics simulations are used to explore the microstructural features of NIIL–H₂S–CH₄ mixture systems. It is found that the hydroxyl groups in the cations is essential in governing the absorption properties of NIILs, including the interaction sites for hydrogen bonding, interaction geometries and energies, diffusion coefficients, and organization of H₂S and CH₄ around cations and anions. A molecular viewpoint to design appropriate ionic liquids for promoting their applications for H₂S capture is provided. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3824–3833, 2013