New nanoporous materials with optimized pore structure in the olefin/paraffin separation by adsorption: Experimental and model-based Evaluation

该项目旨在研究和评估有前途的纳米多孔材料在工业规模上对烯烃/石蜡混合物吸附分离的适用性。所考虑的吸附剂具有孔隙结构，可导致短链烯烃和石蜡的动力学、扩散控制分离或热力学、吸附控制分离。到目前为止，现有的研究只考虑了能更好地吸附目标产物的材料，即烯烃。不幸的是，当试图生产高纯度烯烃时，这需要相当复杂的工艺概念。在这种背景下，具有反向选择性的吸附剂，如在项目早期阶段开发的吸附剂，显得很有吸引力。因此，在这个项目中，我们研究了zif (ZIF-3, -4, -6, -8)，它不仅被证明能更好地吸附石蜡，而且预测它的吸附能力比沸石13X等标准材料更高。另一个有趣的选择是对烯烃具有动力学选择性的材料，例如，磷酸铝SAPO-34 （CHA）。虽然烯烃在该材料中具有良好的扩散率，但它最好吸附在极性和阳离子多孔材料上，从而降低了扩散率。石蜡对非极性和无阳离子材料表现出较强的吸附作用。通过对吸附剂材料的巧妙选择，这些特性可以为变压吸附（PSA）工艺提供新的操作概念，在变压吸附（PSA）工艺中，石蜡或烯烃都可以被更强地保留。利用合适的PSA和VPSA（真空变压吸附）过程的数学模型预测了这些材料在工业应用中的性能。根据一种新的多步骤方法确定所需的模型参数，以实现有效的参数估计和放大。该方法结合了基本的吸附测量与等温和绝热突破实验，使用不同尺度的单柱。最后，PSA实验将在实验室和试点规模进行概念验证研究。

This project aims at investigating and evaluating promising nanoporous materials with respect to their applicability for the adsorptive separation of olefin/paraffin mixtures at industrial scale. The adsorbents considered have pore structures that lead to either kinetic, diffusion-controlled separation or to thermodynamic, adsorption-controlled separation of short-chain olefins and paraffins. Existing studies consider so far only materials that adsorb preferably the target product, which is the olefin. Unfortunately, this necessitates rather complex process concepts when attempting to produce olefins with high purity. Against this background, adsorbents with a reversed selectivity, like those developed in the earlier project phases, appear attractive. In the project, therefore, ZIFs are investigated (ZIF-3, -4, -6, -8), which not only were proven to preferably adsorb the paraffin, but for which also higher adsorption capacities were predicted than for standard materials like zeolite 13X. Another interesting option are materials with a kinetic selectivity for the olefin like, for example, the aluminophosphate SAPO-34 (CHA). While the olefin has a favorable diffusivity in this material, it is preferably adsorbed on polar and cationic porous material, which in turn reduces diffusivity. The paraffin exhibits stronger adsorptive interactions on nonpolar and cation-free materials. By a clever choice of adsorbent materials, these properties may allow new operating concepts for pressure swing adsorption (PSA) processes in which either the paraffin or the olefin is retained more strongly.The performance of industrial applications achievable by these materials is predicted using suitable mathematical models of PSA and VPSA (vacuum pressure swing adsorption) processes. The model parameters required are determined based upon a new multi-step methodology for efficient parameter estimation and scale-up. The approach combines fundamental sorption measurements with isothermal and adiabatic breakthrough experiments using single columns at different scales. Finally, PSA experiments both at laboratory as well as pilot scale will be performed in a proof-of-concept study.