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Mixed gas sorption and transport study in solubility selective polymers.

机译：在溶解度选择性聚合物中混合气体的吸附和传输研究。

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摘要

Membrane separation technology has recently emerged as a potential alternative technique for removing higher hydrocarbons (C3+) from natural gas. For economic reasons, membranes for this application should be organic vapor selective materials such as poly(dimethylsiloxane) (PDMS) or poly(1-trimethylsilyl-1-propyne) (PTMSP). These polymers, often called solubility selective polymers, sieve penetrant molecules based largely on relative penetrant solubility in the polymer.;The sorption and transport properties in such polymers have been reported previously. However, most studies present only pure gas sorption and transport properties. Mixture properties, which are important for estimating membrane separation performance, are less often reported. In addition, mixed gas sorption and diffusion data in such polymers, to the best of our knowledge, have never been investigated before.;This research work provides a fundamental database of mixture sorption, diffusion, and permeation data in solubility selective polymers. Two solubility selective polymers were studied: poly(dimethylsiloxane) (PDMS) and poly(1-trimethylsilyl-1-propyne) (PTMSP). The vapor/gas mixture was n-C4H 10/CH4. CH4 partial pressures ranged from 1.1 to 16 atm, and n-C4H10 partial pressures ranged from 0.02 to 1.7 atm. Temperatures studied ranged from -20 to 50°C. The pure and mixed gas n-C4H 10 and CH4 permeability and solubility coefficients in PDMS and PTMSP were determined experimentally using devices constructed specifically for these measurements. The pure and mixed gas diffusion coefficients were calculated from permeability and solubility data.;In rubbery PDMS, the presence of n-C4H 10 increases CH4 permeability, solubility, and diffusivity. On the other hand, the presence of CH4 does not measurably influence n-C4H10 sorption and transport properties. The n-C4H10/CH4 mixed gas permeability selectivities are lower than those estimated from pure gas measurements. This difference is due to both lower solubility and diffusivity selectivities in mixtures relative to those in pure gas. Plasticization of PDMS by n-C4H10 does little to n-C 4H10/CH4 mixed gas diffusivity selectivity. Increases in mixed gas permeability selectivity with increasing n-C 4H10 activity and decreasing temperature were mainly due to increases in solubility selectivity.;Unlike PDMS, the presence of n-C4H10 decreases CH4 permeability, solubility, and diffusivity in PTMSP. The competitive sorption and the blocking effects significantly reduce CH4 solubility and diffusion coefficients in the polymer, respectively. However, similar to PDMS, the presence of CH4 has no measurable influence on n-C4H10 sorption and transport properties. n-C4H 10/CH4 mixed gas permeability selectivities in PTMSP are higher than those determined from the pure gas measurements. This deviation is a result of higher solubility and diffusivity selectivities in mixtures relative to the pure gas values. Mixed gas permeability, solubility, and diffusivity selectivities in PTMSP increased with increasing n-C 4H10 activity and decreasing temperature.;The partial molar volumes of n-C4H10 and CH4 in the polymers were determined from sorption and dilation data. The dilation isotherms of PDMS and PTMSP in mixtures agree with estimates based on pure gas sorption and dilation measurements. The partial molar volumes of n-C4H10 and CH 4 in PDMS are similar to those in liquids. In contrast, the partial molar volumes of n-C4H10 and CH 4 in glassy PTMSP are substantially lower than those in liquids.;Several models were used to fit the experimental data. For instance, the FFV model, the activated diffusion model, and the Maxwell-Stefan model were employed to describe the mixture permeability data in PDMS. Based on the Maxwell-Stefan analysis, the influence of coupling effects on permeation properties in PDMS were negligible. The dual mode sorption and permeation models were used to describe the mixed gas data in PTMSP. The dual mode permeability model must be modified to account for n-C4H 10-induced reductions in CH4 diffusion coefficients ( i.e., the blocking effect). The FFV model provides poor correlations in PTMSP. There seems to be other factors, besides FFV per se, contributing to the temperature and concentration dependence of diffusion coefficients in PTMSP.
机译：膜分离技术最近成为一种潜在的替代技术，可用于从天然气中去除高级碳氢化合物（C3 +）。出于经济原因，用于此应用的膜应为有机蒸气选择性材料，例如聚（二甲基硅氧烷）（PDMS）或聚（1-三甲基甲硅烷基-1-丙炔）（PTMSP）。这些聚合物，通常称为溶解度选择聚合物，主要基于聚合物中的相对渗透剂溶解度来筛选渗透剂分子。此类聚合物的吸附和传输特性先前已有报道。但是，大多数研究仅显示纯气体的吸附和传输特性。对于估计膜分离性能很重要的混合物性质，报道较少。另外，就我们所知，此类聚合物中混合气体的吸附和扩散数据以前从未进行过研究。这项研究工作提供了溶解度选择性聚合物中混合物吸附，扩散和渗透数据的基础数据库。研究了两种溶解度选择性聚合物：聚（二甲基硅氧烷）（PDMS）和聚（1-三甲基甲硅烷基-1-丙炔）（PTMSP）。蒸气/气体混合物为正C 4 H 10 / CH 4。 CH4分压的范围为1.1至16个大气压，n-C4H10分压的范围为0.02至1.7个大气压。研究温度范围为-20至50°C。使用专门为这些测量构建的设备，通过实验确定了纯气和混合气n-C4H 10和CH4在PDMS和PTMSP中的渗透性和溶解度系数。根据渗透率和溶解度数据计算纯气体和混合气体的扩散系数。在橡胶状PDMS中，n-C4H 10的存在会增加CH4的渗透率，溶解度和扩散率。另一方面，CH4的存在不会显着影响n-C4H10的吸附和传输性质。 n-C4H10 / CH4混合气体渗透率的选择性低于从纯气体测量中估算的选择性。这种差异是由于混合物中的溶解度和扩散选择性相对于纯气体中的较低。 n-C4H10对PDMS的增塑对n-C 4H10 / CH4混合气体的扩散选择性几乎没有。随着n-C 4H10活性的增加和温度的降低，混合气体渗透率选择性的提高主要是由于溶解度选择性的提高。与PDMS不同，n-C4H10的存在会降低PTMSP中CH4的渗透率，溶解度和扩散率。竞争性吸附和封闭效应分别显着降低了CH4在聚合物中的溶解度和扩散系数。但是，类似于PDMS，CH4的存在对n-C4H10的吸附和传输性质没有可测量的影响。 PTMSP中的n-C4H 10 / CH4混合气体渗透率选择性高于从纯气体测量中确定的选择性。该偏差是相对于纯气体值，混合物中较高的溶解度和扩散选择性的结果。 PTMSP中混合气体的渗透性，溶解度和扩散选择性随n-C 4H10活性的增加和温度的降低而增加。; n-C4H10和CH4在聚合物中的部分摩尔体积由吸附和膨胀数据确定。混合物中PDMS和PTMSP的膨胀等温线与基于纯气体吸附和膨胀测量的估计值一致。 PDMS中n-C4H10和CH 4的部分摩尔体积类似于液体中的摩尔体积。相比之下，玻璃状PTMSP中n-C4H10和CH 4的部分摩尔体积明显低于液体中的摩尔体积。;使用了多个模型来拟合实验数据。例如，采用FFV模型，活化扩散模型和Maxwell-Stefan模型来描述PDMS中的混合物渗透率数据。基于Maxwell-Stefan分析，耦合效应对PDMS中渗透性能的影响可以忽略不计。使用双模式吸附和渗透模型来描述PTMSP中的混合气体数据。必须修改双模渗透率模型，以解决n-C4H 10引起的CH4扩散系数降低（即阻塞效应）的问题。 FFV模型在PTMSP中提供了较差的相关性。除FFV本身外，似乎还有其他因素会影响PTMSP中扩散系数的温度和浓度依赖性。

著录项

  • 作者

    Raharjo, Roy Damar.;

  • 作者单位

    The University of Texas at Austin.;

  • 授予单位 The University of Texas at Austin.;
  • 学科 Engineering Chemical.
  • 学位 Ph.D.
  • 年度 2007
  • 页码 234 p.
  • 总页数 234
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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