对二甲苯（PX）是一种重要的石油化工产品，主要用于聚酯的生产。当前，我国PX自给率不足50%，积极开展PX合成方面的研究具有重要的现实意义。通过甲苯甲醇直接烷基化合成PX是典型的择形催化过程。微孔分子筛ZSM-5和MCM-22 是常用的择形催化剂，但其外表面酸性位的存在会降低其择形性能。通过络合浸渍法为PX的合成过程设计金属氧化物改性微孔分子筛择形催化剂，可以实现在覆盖分子筛外表面酸性位的同时而不影响其孔道内的酸性质，进而实现在获得高选择性的同时保持催化剂的高活性和高稳定性。本项目拟研究：(1) 络合浸渍过程中络合物稳定性的过程优化与控制；(2) 金属络合物在分子筛外表面的分散机制及其与氧化物覆盖分子筛外表面酸性位效果的相关性；(3) 络合浸渍法制备的金属氧化物改性微孔分子筛催化剂对合成PX过程的择形性能及规律。本课题的研究将为石油化工择形催化剂的制备领域提供一条便捷、高效的新途径。

Para-xylene (PX) is one of the most important aromatics widely used as the raw materials of polyethylene terephthalate and polyester. Recently, the self-sufficient rate of PX in China is less than 50%. Therefore, it is meaningful for carrying out some research on the synthesis of PX. Commercially, the synthesis of PX by alkylation of toluene with methanol catalyzed by zeolites such as ZSM-5 and MCM-22 is typically shape-selective catalysis process.The design and preparation of shape-selective catalysts therein is the key to obtain a highly shape-selectivity for the production of PX. However, the acidic sites on the external surface of zeolite usually result in the decrease in para-selectivity. The metal oxides modefied zeolites shape-selective catalysts prepared by complexation-impregnation method have been developed, which can maintain the cover of the external acidic sites and the protection of the inner acidic sites on zeolite can be achieved simultaneously. Consequently, the catalysts prepared by complexation-impregnation method exhibit excellent para-selectivity, activity and stability in shape-selective catalysis process. This object covers the following three parts: (1) the process optimization and control for the stability of complex during the complexation-impregnation process; (2) the dispersion mechanism of the metal complexs on the external surface of zeolites and the relationship with the cover of the external surface acidic sites of zeolite; (3) the catalytic performance and the principle thereof for the synthesis of para-xylene over metal oxides modefied zeolites prepared by complexation-impregnation method. The research of this object is believed to provide a further outline for the preparation of highly effcient shape-selective catalysts.