甲醇制烯烃反应中多级孔ZSM-11基成型催化剂制备及其应用研究

Study on preparation and application of hierarchical porous ZSM-11 based shaping catalysts in methanol-to-olefins reaction

采用自主合成的多级孔ZSM-11为活性组分,结合X射线衍射、N2吸/脱附及吡啶吸附傅里叶变换红外光谱等分析,在实验室小试实验装置上考察了ZSM-11基成型催化剂制备过程中,载体、粘结剂和分子筛三者的协同效应。采用喷雾造粒法对催化剂进行放大生产,并在中试试验装置上评价了ZSM-11工业剂的甲醇制烯烃反应性能。结果表明,载体和粘结剂的结构性质对甲醇制烯烃反应性能影响较小,骨架中四配位铝羟基产生的L酸性位是导致甲醇分解、氢转移和积炭反应的主要因素,故ZSM-11基成型催化剂中的载体选取双层二八面体结构的高岭土,粘结剂选择硅溶胶。中试实验结果表明,反应300 h内甲醇转化率维持在96.1%~99.9%。催化剂稳定性好,产物中丙烯、乙烯及丁烯收率分别维持在16.0%、3.4%和7.8%左右,实现了甲醇向烯烃的高效转化。

The self-synthesized hierarchical porous ZSM-11 was used as the active component,and the synergistic effects of carrier,binder,and zeolite during the preparation were investigated in the laboratory combined with powder X-ray diffraction,N2 adsorption/desorption and pyridine adsorption Fourier-transform infrared spectra.Then the catalyst was scaled up for production and the reaction performance of ZSM-11 catalyst for methanol-to-olefins was evaluated on a pilot plant.The results show that the structural properties of the support and binder have little effect on the methanol-to-olefin reaction performance.The L acid sites generated by the tetracoordinated aluminum hydroxyl groups in the framework are the main factors leading to methanol decomposition,hydrogen transfer and carbon deposition reactions.Therefore,in the shaped ZSM-11 catalysts,the support is kaolin with double-layer dioctahedral structure,and the binder is inert silica sol.On this basis,the ZSM-11 industrial agents with abundant mesopores and meeting the requirements of fluidized bed were prepared by spray granulation.The results of the pilot-scale experiment show that the methanol conversion rate is obtained at 96.1%~99.9%within 300 h.The catalysts exhibited good stability,and the yields of propylene,ethylene and butene in the product are about 16.0%,3.4%and 7.8%,respectively,realizing the efficient conversion of methanol to olefins.