亚临界和超临界二氧化碳-甲醇混合气相及液相区中甲醇核磁弛豫速率比较研究（英文）

发布时间：2018-05-20 17:35

本文选题：二氧化碳-甲醇混合物 + 偶极-偶极作用机理　；参考：《物理化学学报》2016年11期

【摘要】：用核磁共振氢谱测量了不同温度(293.15和308.15 K)及压力高达25 MPa下二氧化碳-甲醇混合气相(超临界)及液相区(亚临界)中甲醇(羟基及甲基)的纵向弛豫时间T1,exp。本工作的目的是考察近临界区二氧化碳-甲醇混合物的压力、温度及组成对甲醇弛豫速率的影响,揭示混合物不同相区(气相及液相区)中自旋-晶格弛豫(SLR)过程的机理。此外,还对比研究了等温条件下超临界和亚临界混合气相及液相区中甲醇的SLR速率1/T1,exp随混合物密度的变化规律。研究发现,在本工作所涉及的温度及压力区间,对于纯甲醇或液相区其SLR过程是以偶极-偶极(DD)作用机理为主导,而在气相区SLR过程则是以自旋-转动(SR)作用机理占优势,也即,超临界和亚临界二氧化碳-甲醇混合物的SLR过程在不同相区有不同的作用机理控制。由于甲醇的SLR弛豫速率1/T1,exp是由甲醇分子间及分子内的DD作用和SR作用三部分共同决定的,所以研究超临界和亚临界二氧化碳-甲醇混合物的SLR弛豫速率随压力、浓度及温度的变化规律有助于提供更多该混合物不同相态区分子间相互作用的动态学信息。
[Abstract]:The longitudinal relaxation time T _ (1) expan of methanol (hydroxyl and methyl) in the liquid phase and in the liquid phase (supercritical) was measured by nuclear magnetic resonance (NMR) at different temperatures (293.15 and 308.15 K) and pressure up to 25 MPa. The purpose of this work is to investigate the effects of pressure, temperature and composition on the relaxation rate of methanol in the near critical region, and to reveal the mechanism of spin lattice relaxation (SLR) process in different phase regions (gas and liquid phase) of the mixture. In addition, the SLR rate of methanol in the supercritical and subcritical gas mixtures and in the liquid phase region under isothermal conditions is compared and studied with respect to the density of the mixture. It is found that in the range of temperature and pressure involved in this work, the SLR process is dominated by dipole-dipole interaction mechanism in the pure methanol or liquid phase region, while in the gas-phase region the SLR process is dominated by the spin-rotation mechanism. In other words, the SLR process of supercritical and subcritical CO2 / methanol mixtures is controlled by different mechanisms in different phase regions. Since the SLR relaxation rate of methanol is determined by the interaction of DD and SR between molecules and molecules of methanol, the SLR relaxation rate of supercritical and subcritical CO _ 2-methanol mixtures is studied with pressure. The variation of concentration and temperature is helpful to provide more dynamic information on the interaction between molecules in different phase regions of the mixture.
【作者单位】：郑州大学化学与分子工程学院;
【基金】：supported by the National Natural Science Foundation of China(21543009,21073167,J1210060) Innovative Research Grant for Undergraduate Students of National/Zhengzhou University,China(201410459047,201510459046,2016xjxm259)~~
【分类号】：O623.411;O642.5

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