卤代甲烷制丙烯反应中分子筛孔道结构与催化性能的构效关系研究

The development of efficient non-oil-based propylene production routes is the fundamental path to meet the increasing demand of propylene in the case of oil resources shortage. The preparation of propylene from methane via methyl halides is an ideal approach compared with the others and the reaction from methyl halide to propylene (MeXTP) is the key step. The MeXTP reaction is carried on zeolite catalysts. However, the relationship between pore structure and catalytic activity of zeolites were mostly based on the size of inner space and hydrocarbon pool species, which could not provide comprehensive theoretical guidance for the development of high performance catalysts. Therefore, in this project, a series of characteristic zeolites will be taken out to investigate the relationship between pore structure and catalytic activity based on the conversion capacity and product distribution. Furthermore, the nature of such relationship will be explored by hydroxyl and hydrocarbon pool species characterization. The project will provide significant evidence for the design of high performance catalysts of the MeXTP reaction, and pave the way for the industrialization of the methane to propylene "two-step" process.

随着石油资源的日益短缺，开发节能高效的非油基丙烯生产途径，是满足日益增长的丙烯需求的根本途径。由甲烷经卤代甲烷制丙烯是一条理想的生产路线，其中卤代甲烷制丙烯反应（MeXTP）是关键。分子筛作为卤代甲烷制丙烯反应的催化剂，对其孔道结构与催化性能构效关系的认识尚不完善，目前仅靠骨架空间与烃池物种的尺寸建立关联，使得现有的构效关系并不能为高效催化剂的开发提供准确的理论指导。为此，本项目拟选择具有典型孔道结构的系列分子筛材料，基于卤代甲烷转化能力和产物分布的异同，获得分子筛孔道结构与催化性能的关联规律，并通过探究反应过程中羟基的变化规律及烃池物种分布，揭示孔道结构对催化性能影响的本质。本项目将为卤代甲烷制丙烯反应高效催化剂的设计提供科学依据，为“两步法”甲烷制丙烯工艺走向工业化奠定坚实的基础。

以卤代甲烷为平台分子的“两步法”由甲烷制备丙烯的反应路径受到了广泛关注，而卤代甲烷制丙烯是该路径的关键。分子筛作为该反应的催化剂，对其孔道结构与催化性能构效关系的认识尚不完善。本项目以卤代甲烷为目标反应展开研究，内容分为三个部分：第一，选取ZSM-5及具有类比性的分子筛材料组成研究系列，通过水热合成及F改性成功制备了酸性、晶粒尺寸等性质相似的系列材料；第二，获取分子筛孔道结构与催化活性的关联规律，发现转化能力、丙烯选择性以及稳定性均随孔道维数增多而上升；第三，对高效催化剂进行了探索，发现ZSM-11是卤代甲烷制丙烯反应的优良催化剂，并且通过F改性及后续碱处理，不但能大幅提高催化性能，还能保持良好的稳定性。这些研究结果拓展了对分子筛结构性质与其催化作用关系的认识，发展了新的催化剂优化方法，为高效稳定的卤代甲烷制丙烯催化剂的开发提供了科学依据。