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首页> 外文期刊>Crystal growth & design >Thermodynamic Polymorph Selection in Enantiotropic Systems Using Supersaturation-Controlled Batch and Semibatch Cooling Crystallization
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Thermodynamic Polymorph Selection in Enantiotropic Systems Using Supersaturation-Controlled Batch and Semibatch Cooling Crystallization

机译：使用过饱和控制的批量和半散热结晶的脱色系统中热力学多晶型选择

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摘要

Supersaturation control (SSC) is a simple yet effective technique to control, among other properties, the purity, shape, and polymorphic form of crystals during the crystallization process. However, for the enantiotropic polymorph systems it is difficult to efficiently operate the traditional batch SSC because of the intersecting solubility lines and hence the temperature dependence of polymorph stability. From a thermodynamic perspective, the transition temperature in a batch crystallization is the minimum final temperature for the polymorph that is stable at high temperature, and it is the maximum initial temperature for the polymorph that is stable at lower temperatures. The existence of a transition point between the two polymorphs often makes it difficult to produce consistently one or the other form with good yield in a batch crystallization process. Due to the constant-temperature operation, continuous tank crystallizers could overcome this problem, but the scale of production and other technology challenges often does not justify their application. This paper proposes a semibatch cooling SSC strategy, having as the manipulated variable the feed flow rate of a high-temperature, concentrated inlet stream in the same solvent system as used in the crystallization process. The crystallizer temperature is fixed under the transition temperature, and the concentration corresponding to the supersaturation set point is undersaturated for the counter polymorph, ensuring in this way thermodynamic polymorph selection. The system is presented through the case study of p-aminobenzoic acid (PABA) crystallization from ethanol for SSC of both enantiotropic polymorphs: alpha-PABA can be obtained in both batch and semibatch operation. According to the literature, beta-PABA cannot be easily obtained in batch cooling crystallization, but the semibatch setup was able to produce it consistently without yield limitations due to the transition temperature.
机译：超饱和对照（SSC）是一种简单而有效的技术，可以在结晶过程中控制晶体的其他性质，纯度，形状和多晶相形式。然而，对于对脱嗜酸性多晶型物系统，由于相交的溶解度线，因此难以有效地操作传统的批量SSC，因此稳定性稳定性的温度依赖性。从热力学的角度来看，批量结晶中的过渡温度是在高温下稳定的多晶型物的最低最终温度，并且是在较低温度下稳定的多晶型物的最大初始温度。两种多晶型物之间的过渡点的存在通常使得难以在批量结晶过程中始终生产一种或其他形式，并且在批量结晶过程中具有良好的产率。由于恒温操作，连续罐结晶器可以克服这个问题，但生产规模和其他技术挑战往往不仅仅是其应用。本文提出了半冷却SSC策略，作为操纵变量，在结晶过程中使用的相同溶剂系统中的高温浓缩入口流的进给流速。结晶器温度在转变温度下固定，对应于过饱和设定点的浓度对于反相晶型物，以这种方式确保热力学多晶型物选择。该系统通过对乙醇的乙醇结晶来提出，用于SSC的抗嗜酸性多晶型物：α-PABA可以在两批和半术操作中获得。根据文献，不能在批量冷却结晶中容易地获得β-PABA，但是半斑点设置能够始终如一地产生由于过渡温度而没有收益限制。

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  • 来源
    《Crystal growth & design》 |2019年第11期|共12页
  • 作者

    Zhang Teng; Szilagyi Botond; Gong Junbo; Nagy Zoltan K.;

  • 作者单位

    Tianjin Univ Sch Chem Engn &

    Technol State Key Lab Chem Engn Tianjin 300072 Peoples R China;

    Purdue Univ Davidson Sch Chem Engn W Lafayette IN 47907 USA;

    Tianjin Univ Sch Chem Engn &

    Technol State Key Lab Chem Engn Tianjin 300072 Peoples R China;

    Purdue Univ Davidson Sch Chem Engn W Lafayette IN 47907 USA;

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  • 正文语种 eng
  • 中图分类 晶体学;
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