低成本高性能介孔/多级孔分子筛设计与制备

It is highly desirable to design and preparation of novel hierarchically porous zeolites with high catalytic performance and low cost, due to the demand of increasing the efficiency of heavy oil upgrading or petrochemical process. In this project, we plan to introduce heteroatoms (e.g. B) into the framework of NaY zeolites as unstable sites to preparation mesoporous Y zeoltes. Then, the migration of heteroatoms and accordingly its effect on the dealumination during the post-treatment, the formation mechanism of mesopores together with the adjustment of acidic sites would be intensively investigated. Based on these results, high quality USY prepared in the absence of organotemplates and extra-procedures is expected. Furthermore, novel method for preparation of hierarchically porous Y zeolites with Si-rich surface and cage-like pores would be developed after the research on the adjust the distribution of Al, “Core-Shell” with Si-rich surface, as well as the effect on dealumination and desilication during the post-treatment. Design novel bi-functional polymers as template to the preparation of mesoporous zeolites based on the understanding of the formation mechanism of mesoporous zeolites. Moreover, we plan to research the formation mechanism of solvent-free synthesis of mesoporous zeolite in the absence of bulky template and develop novel route for preparation of mesoporous zeolite with low cost. All these products would be thorough characterized and evaluated by various techniques and catalysis, which would be of great importance for preparation of high quality catalysts with low cost in industry.

低成本、高性能介孔/多级孔分子筛是开发具有竞争力的高端石油化工催化剂的需要。针对用作催化裂化等催化剂主活性组分的Y型沸石，拟首先在合成NaY沸石时预置硼等杂原子作为结构不稳定性位点，通过研究后处理过程中杂原子的迁移对骨架铝脱除的影响机理，掌握介孔形成和酸性的调控机制，在不使用有机模板剂和不增加后处理过程步骤的前提下，获得性能优良的介孔USY材料。拟通过NaY沸石硅铝分布的调控、以及对富硅壳层结构对后续酸处理脱铝及碱处理脱硅作用影响机制的揭示，发展简捷的表面富硅、笼状多级孔Y沸石的设计制备新方法；对于高硅或择形催化材料，拟通过介孔沸石导向形成机理的研究，设计制备低成本双功能高分子聚合物模板剂，实现介孔沸石的定向合成。同时，研究无溶剂条件下介孔沸石形成过程的固相转化作用机制，获得介孔沸石制备新方法。通过表征和催化性能评价，反馈优化制备方法，最终获得制备高性能低成本催化材料的科学方法和关键技术。

扩散是影响重油加工等催化转化过程中分子在催化剂中传输、最终影响其催化效果的关键因素。针对这一背景，本项目发明了在NaY沸石骨架引入硼、镁等杂原子，进而通过水热处理的方法制备介孔Y沸石的低成本方法，揭示了杂原子的引入及其在水热处理过程中的迁移对Y沸石介孔形成的作用机制。该方法流程短、成本低，孔道连通性好，酸性适宜，改善了活性中心可接近性和效率。例如，通过引入催化量的硼元素制备的NaY沸石经改性后制备的USY-B沸石，和对比样常规USY沸石相比，介孔体积相对增加了46％，并显著改善了介孔的连通性，由此我们提出了在沸石后处理过程“催化造介孔”的概念。在重油的催化裂化反应评价中，和对比样USY催化剂相比，含有USY-B沸石的催化剂汽油收率提高2.1wt%，而液化气产率降低1.7wt%，焦炭产率持平或略有降低；基于SiCl4气相超稳所得Y沸石（DY）特性，利用富铝、富硅区域在酸、碱化学环境下化学反应性质的差异，发明了“酸+碱”耦合处理、通过选择性脱铝/脱硅制备富含介孔的多级孔Y沸石的低成本方法，利用该方法制备的Y沸石介孔体积比常规USY沸石介孔体积提高一倍以上。利用该材料制备的催化裂化催化剂和常规USY催化剂相比，重油催化裂化反应评价汽柴油收率提高3.67wt%以上，焦炭产率降低0.44wt%以上，在低结焦的前提下显著提高了轻油收率；酸碱处理DY形成介孔的机理研究表明，“脱铝”在晶体内富铝区域形成丰富的硅羟基窝，而脱硅则通过脱除硅羟基窝附近及晶体富硅区域骨架硅，形成中空+介孔体系（笼状多孔），为后续研究提供了思路；开发了通过酸和热耦合作用对Beta沸石进行酸性和脱铝调变的有效方法；掌握了高分子聚合物模板剂的设计/合成技术，揭示了聚合物模板的导向介孔的规律；掌握了无溶剂、无聚合物模板条件下制备介孔ZSM-5沸石的方法，初步揭示了无溶剂条件下气体通过膨胀作为介孔模板的成孔机制，这些材料在催化生物质加氢等方面显示出优异性能。