强氢键识别和分子筛分协同的多功能吸附剂的构建及复杂裂解气脱炔性能研究

Selective removal of alkynes from pyrolysis gases is the key technology in the production of polymer-grade olefins. The process of front-end alkyne removal have the advantage of energy-efficient and simple. However, the composition of pyrolysis gases are complex (including C1-C5 fractions), and the existing front-end selective hydrogenation technology can hardly achieve the deep removal of several kinds of alkyne at the same time. Therefore, it is urgent to develop a new front-end alkyne removal technology. Adsorptive separation technology, with the characterizations of energy-efficient and deep removal, is a promising technology for the separation of alkyne/olefin. However, the conventional adsorbents have difficulties to specifically capture multi-type alkynes and propadiene from mixed cracking gas. In addition, the existing adsorbent can adsorb higher hydrocarbon easily. In this proposal, we plan to prepare multi-functional ionic hybrid porous materials with strong hydrogen-bonding recognition and molecular sieving. The unique hydrogen-bonding properties of inorganic anions can achieve the specific recognition of acetylene, propyne and propadiene. Meanwhile, the exclusion of higher hydrocarbon can be realized by precisely tuning of the porous cage structures. To provide the foundation for the development of new front-end alkyne removal technology, we plan to study the tuning rules of structure and properties of multi-functional ionic hybrid porous materials, explore the interaction mechanism of C2-C5 alkyne/olefin with ionic hybrid porous materials, study the molecular-sieving properties, and investigate the fixed bed separation performance of mixed gases. Our research group is well-experienced in the separation of alkyne/olefin, and some preliminary results have been obtained.

裂解气中炔烃的选择性深度脱除是聚合级烯烃制备过程中的关键技术，前脱炔工艺具有能耗低、流程简洁等优点，然而裂解气成分复杂（含C1-C5），现有加氢前脱炔技术难以同时实现多类炔烃的深度脱除，急需发展前脱炔新技术。吸附分离是具有良好应用前景的炔烃/烯烃分离技术，具有能耗低、可深度脱除等优点，但现有吸附剂难以从复杂裂解气中专一性的捕集多类炔烃和丙二烯组分，且易吸附高碳烃失活。本项目拟合成强氢键识别和分子筛分协同作用的多功能离子杂化材料，利用无机阴离子的氢键识别能力实现乙炔、丙炔和丙二烯的专一性识别，精准构建具有笼形孔道结构的材料，实现高碳烃的尺寸排阻筛分。为此，拟研究多功能离子杂化材料的结构性质调控规律，研究C2-C5烯烃/炔烃与离子杂化材料的相互作用机理和分子筛分性能，考察混合气的固定床动态分离性能，为发展吸附分离前脱炔新技术提供基础。项目组在烯烃炔烃分离方向已有较好研究基础，并获初步研究成果。

裂解气中乙炔、丙炔以及丙二烯的选择性脱除是石油化工分离过程中的难点和关键技术之一。然而现有吸附材料难以从复杂裂解气中专一性的捕获多类炔烃组分。针对复杂体系中炔烃以及丙二烯同时脱除的难题，本项目基于裂解气各分子间的结构性质差异，设计合成了兼具强氢键识别和分子筛分作用的离子杂化多孔材料，实现了炔烃的专一性分子识别，以及C4及以上高碳烃的尺寸排阻。本研究的结论有助于发展高效低能耗裂解气前脱炔新方法。.本项目按计划进行，取得的主要进展有：（1）合成了兼具强氢键识别和分子筛分功能的离子杂化多孔材料，通过调变无机阴离子、有机配体和金属节点调控材料的孔道结构和孔内化学性质，实现了孔道尺寸百分之一纳米精度范围内的连续调控，获得了配位单元与离子杂化多孔材料结构调控规律。（2）通过单组分静态吸附实验以及固定床动态穿透实验评估了系列离子杂化多孔材料对低碳烃混合气的分离性能。归纳了材料孔道结构与吸附容量和选择性之间的构效关系，并模拟混合裂解气组成来评价材料对复杂裂解气混合气的分离性能，其中具有客体分子和温度双重响应的多功能“分子分离器”ZU-33可以从含十余种C1-C4组分复杂裂解气中一步深度脱除炔烃和丙二烯。（3）通过量化模拟和晶体学分析相结合手段从分子层面上揭示了强氢键识别耦合分子筛分的选择性吸附分离机理，在吸附炔烃和丙二烯分子时，材料框架结构会发生自适应结构形变以更好地匹配不同客体分子的构型，对乙炔、丙炔和丙二烯分子表现出强相互作用，从而实现了含十余种C1-C4组分复杂裂解气中炔烃和丙二烯的一步脱除。在本项目的资助下，在Adv. Mater.、Small、AIChE J.、Nano Res.等期刊发表标注资助的论文15篇，申请发明专利4项。本项目取得的研究成果为裂解气脱炔提供了一种新思路。