Bulk and Confined Benzene-Cyclohexane Mixtures Studied by an Integrated Total Neutron Scattering and NMR Method
Bulk and Confined Benzene-Cyclohexane Mixtures Studied by an Integrated Total Neutron Scattering and NMR Method
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DOI：
10.1007/s11244-021-01437-w
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发表时间：
2021-04-23
影响因子：
3.6
通讯作者：
Hardacre，Christopher
中科院分区：
文献类型：
--
作者：
Hughes，Terri-Louise;Falkowska，Marta;Hardacre，Christopher
在此，我们研究了环己烷和苯的混合物在体液相和限制在MCM-41介孔中的情况。用全中子散射(TNS)研究了体相混合物，用一种新的流动利用、TNS和核磁共振相结合的系统(Flow Neu核磁共振)研究了受限混合物，所有体系都用经验势能结构修正(EPSR)进行了分析。Flow Neu核磁共振装置通过核磁共振提供精确的时间分辨化学样品成分，克服了在改变化学成分(如化学反应)的TNS实验中通常发现的数据计算模拟中确保成分一致性的困难。与液体混合物不同的是，在垂直于碳-碳键的区域中，在距离环己烷环很短的距离内发现了垂直取向的苯分子。在限制碳氢化合物混合物时，发现不同的分子二聚体在较短的距离内具有更强的平行取向偏好。在较长的第一配位壳层距离时，混合物中的类苯分子的空间结构也在限制时发生了变化。
Herein mixtures of cyclohexane and benzene have been investigated in both the bulk liquid phase and when confined in MCM-41 mesopores. The bulk mixtures have been studied using total neutron scattering (TNS), and the confined mixtures have been studied by a new flow-utilising, integrated TNS and NMR system (Flow NeuNMR), all systems have been analysed using empirical potential structure refinement (EPSR). The Flow NeuNMR setup provided precise time-resolved chemical sample composition through NMR, overcoming the difficulties of ensuring compositional consistency for computational simulation of data ordinarily found in TNS experiments of changing chemical composition—such as chemical reactions. Unique to the liquid mixtures, perpendicularly oriented benzene molecules have been found at short distances from the cyclohexane rings in the regions perpendicular to the carbon–carbon bonds. Upon confinement of the hydrocarbon mixtures, a stronger parallel orientational preference of unlike molecular dimers, at short distances, has been found. At longer first coordination shell distances, the like benzene molecular spatial organisation within the mixture has also found to be altered upon confinement.