Cabooter Deirdre, Lestremau François, de Villiers André, Broeckhoven Ken, Lynen Frédéric, Sandra Pat, Desmet Gert
Vrije Universiteit Brussel, Department of Chemical Engineering, Pleinlaan 2, 1050 Brussels, Belgium.
J Chromatogr A. 2009 May 1;1216(18):3895-903. doi: 10.1016/j.chroma.2009.02.079. Epub 2009 Mar 5.
The present study investigates how strong the kinetic plot method is influenced by the changes in plate height, retention factor and apparent column permeability that arise under conditions of very high pressure. More precisely, the study investigates how well a set of performance measurements conducted on a single short column can be used to predict the performance of a long sequence of coupled columns. This has been investigated for the two practically most relevant thermal conditions, i.e., that of a forced-air oven and that of a still-air oven. Measuring column performance data for acetophenone and benzene on a series of coupled 3.5 microm columns that could be operated up to 1000 bar, it was found that the kinetic plot method provides accurate predictions of time versus efficiency for the still-air oven systems, over the entire range of investigated pressures and column lengths (up to 60 cm), provided k' and K(v0) are evaluated at the maximal pressure. For the forced-air oven which leads to worse performances than the still-air oven, the kinetic plot prediction is less accurate, partly because the thermal conditions (near-isothermal) tend to vary if the number of coupled columns increases. The fact that the thermal conditions of the column wall might vary with the column length is an additional complexity making very-high pressure separations less predictable and harder to interpret and model.
本研究调查了在极高压力条件下出现的塔板高度、保留因子和表观柱渗透率变化对动力学曲线法的影响程度。更确切地说，该研究调查了在单个短柱上进行的一组性能测量能在多大程度上用于预测一系列耦合柱的性能。针对两种实际中最相关的热条件，即强制通风烘箱条件和静止空气烘箱条件进行了此项研究。在一系列可操作至1000巴的耦合3.5微米柱上测量苯乙酮和苯的柱性能数据，结果发现，对于静止空气烘箱系统，在整个研究压力和柱长范围（最长60厘米）内，只要在最大压力下评估k'和K(v0)，动力学曲线法就能准确预测时间与效率的关系。对于导致性能比静止空气烘箱差的强制通风烘箱，动力学曲线预测的准确性较低，部分原因是如果耦合柱的数量增加，热条件（接近等温）往往会发生变化。柱壁的热条件可能随柱长而变化这一事实增加了复杂性，使得超高压分离更难预测、更难解释和建模。
