γ-Al2O3/SAPO-34复合催化剂及其对MTO反应的催化性能

采用介孔γ-Al₂O₃对微孔SAPO-34分子筛进行复合改性，利用水热包覆技术制备了γ-Al₂O₃/SAPO-34复合催化剂，研究了复合催化剂物化性质及其对甲醇制低碳烯烃(MTO)反应的催化性能。采用X射线衍射仪(XRD)、傅里叶红外光谱仪(FT-IR)、扫描电子显微镜(SEM)、氨气程序升温脱附法(NH₃-TPD)和物理吸附仪(BET)等手段对不同γ-Al₂O₃/SAPO-34复合催化剂的晶相组成、骨架结构、微观形貌、表面酸性及孔结构进行分析表征。结果表明，与物理共混催化剂相比，水热包覆法制得γ-Al₂O₃/SAPO-34复合催化剂形成了包覆相和微-介孔结构(微孔比表面积123 m²/g，介孔比表面积95 m²/g)。在常压、催化剂装载量1 g、水/醇摩尔比2/1、原料进料体积空速2 h^-1、N²流速20 mL/min、反应温度380  ℃条件下，复合催化剂表现出优越的催化性能和反应寿命，甲醇转化率和低碳烯烃选择性分别达到100%和88%，催化剂寿命达到990 min，与物理共混催化剂相比，复合催化剂寿命延长了640 min。

γ-Al2O3/SAPO-34 Composite Catalyst and Its Catalytic Performance in MTO Reaction

The microporous SAPO-34 molecular sieve was promoted by using mesoporous γ-Al₂O₃ to prepare γ-Al₂O₃/SAPO-34 composite catalyst, and the physicochemical properties and catalytic performance for methanol to lower olefin (MTO) of the composite catalysts fabricated via hydrothermal coating route were investigated in this paper. These obtained composite catalysts were extensively characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), NH3-temperature programmed desorption (NH₃ -TPD) and Brunner Emmet Teller (BET) techniques to investigate their crystalline phase, skeletal structure, morphology, surface acidity and pore structure. Compared with the physical blending catalyst, the homogeneous continuous coating phase and micro-mesoporous structure (microporous specific surface area of 123 m²/g, mesoporous specific surface area of 95 m2/g) were successfully obtained in the composite catalyst fabricated via hydrothermal coating route. The composite catalyst exhibited superior catalytic performances and reaction life with methanol conversion of 100 %, light olefins selectivity of 88 %, and catalytic lifetime of 990 min under the conditions of atmospheric pressure, reaction temperature of 380 ℃, catalyst loading of 1 g, hydro/alcohol molar ratio of 2/1, nitrogen flow rate of 20 mL/min and feed speed of 2 h ^-1. Compared with the physical blending catalyst, the catalytic lifetime of the composite catalyst was extended by 640 min.