具有高丙烯、低芳烃选择性的新型甲醇制烯烃沸石催化材料

The demand of light olefins, especially propylene as one of the most important intermediates for production of polymers, has been continually increasing, and methanol-to-olefins (MTO) reaction is considered as an interesting alternative process because methanol could be easily produced from syngas. In the MTO, typical catalysts are HZSM-5 and SAPO-34 zeolites, where microporous structure of zeolites plays important roles for the selective formation of ethylene and propylene. SAPO-34 zeolite with small pore sizes (3.8?) generally show high selectivity for ethylene, while ZSM-5 zeolite with medium pore sizes (5.5?) usually results in the formation of a large amount of relatively bulky hydrocarbons such as aromatics although ZSM-5 has higher proplyene selectivity than SAPO-34. .. In this project, we would like to use ZSM-34 zeolite with pore size of 5.0? to catalyze MTO, giving high selectivity for propylene and low selectivity for aromatics. Moreover, we would like to introduce mesoporosity into the crystals or reduce crystal sizes of ZSM-34 to enhance the mass transfer, which is favorable for the improvement of propylene selectivity; we would like to change acidic property of ZSM-34, which is helpful for the increase of catalytic stability; we would like to devote to organotemplate-free synthesis of ZSM-34, which is a critical factor for industrial applications of ZSM-34 due to its high cost by conventional organotemplated synthesis... Additionally, in this project, we also want to design and synthesize novel core-shell zeolite catalysts, where the shell offers a good selectivity for the formation of propylene and the core plays catalytically active phase. Because there are not active sites in the shell, the core-shell zeolite catalysts should have good catalyst life. These features are very helpful for designing and synthesizing novel MTO catalysts in the future.

丙烯是最重要的化工原料之一，而通过甲醇转化为烯烃是当前生成丙烯的重要方法之一。在该转化中，最常用的催化材料为SAPO-34和ZSM-5两类沸石。SAPO-34沸石的孔径为3.8埃，该沸石小的孔径很好地限制了甲醇向芳烃大分子的转化，但所生成产物中的丙烯选择性仍然较低。ZSM-5的孔径相对较大(5.5埃)，甲醇可以有效地转化为丙烯，但是形成了较多的芳烃副产物。本项目拟采用孔径在5.0埃的ZSM-34结构沸石作为新型催化剂进行甲醇制烯烃研究，期望在所形成的产物中具有高的丙烯和低的芳烃选择性。在此基础上，期望通过对ZSM-34引入介孔结构或降低沸石晶粒大小以提高反应的传质性能进一步提高丙烯的选择性；通过改变沸石的酸性质以改善该催化材料的反应寿命；通过实现对该沸石的无模板合成技术以降低沸石合成成本、增加该沸石的应用可行性。进一步，本项目还设计合成孔径4.5埃的RUB-41沸石为壳的新型核壳催化材料

丙烯是最重要的化工原料之一，而通过甲醇转化为烯烃是当前生成丙烯的重要方法之一。在该转化中，最常用的催化材料为 SAPO-34 和 ZSM-5 两类沸石。SAPO-34 沸石的孔径为 3.8 埃，该沸石小的孔径很好地限制了甲醇向芳烃大分子的转化，但所生成产物中的丙烯选择性仍然较低; ZSM-5 的孔径相对较大(5.5 埃)，甲醇可以有效地转化为丙烯，但是形成了较多的芳烃副产物。本项目采用了孔径在 5.0 埃的 ZSM-34 结构沸石作为新型催化剂进行甲醇制烯烃研究，正如我们所期望的，在所形成的产物中具有高的丙烯和低的芳烃选择性。进一步，又通过对 引入介孔结构或降低沸石晶粒大小以提高反应的传质性能进一步提高丙烯的选择性；通过实现对该沸石的无模板合成技术以降低沸石合成成本、增加该沸石的应用可行性。在此基础上，又进行了无溶剂合成沸石分子筛的研究工作，还进行了沸石分子筛浸润性的调控。