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

本项目旨在研究和评价有前景的纳米多孔材料在工业规模上吸附分离烯烃/烷烃混合物的适用性。所考虑的吸附剂的孔结构导致了动力学的、扩散控制的分离或热力学的、吸附控制的短链烯烃和烷烃的分离。到目前为止，现有的研究只考虑了优先吸附目标产物的材料，即烯烃。不幸的是，当试图生产高纯度的烯烃时，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，就像在早期项目阶段开发的那样，看起来很有吸引力。因此，在该项目中，研究了ZIF(ZIF-3，-4，-6，-8)，它们不仅被证明对石蜡有较好的吸附能力，而且预测其吸附容量比标准材料(如13X沸石)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)。虽然烯烃在这种材料中具有良好的扩散性，但它更好地吸附在极性和阳离子多孔材料上，这反过来又降低了扩散性。烷烃在非极性和无阳离子材料上表现出较强的吸附相互作用。通过对吸附材料的巧妙选择，这些性质可能为变压吸附(PSA)过程提供新的操作概念，在PSA过程中，烷烃或烯烃被保持得更强。利用PSA和VPSA(真空变压吸附)过程的适当数学模型，预测了这些材料可实现的工业应用的性能。所需的模型参数是根据一种新的多步方法确定的，以实现有效的参数估计和放大。该方法将基本吸附测量与等温和绝热穿透实验相结合，使用不同尺度的单柱。最后，将在实验室和中试规模上进行PSA实验，并进行概念验证研究。

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.