【作者】 王红霞；

【导师】 李建伟；

【作者基本信息】 北京化工大学 ， 化学工程与技术， 2010， 硕士

【摘要】 采用水热合成法制备了一系列SAPO-34分子筛,并进行了XRD表征,考察了硅源、原料配比等合成条件对SAPO-34分子筛结晶度的影响。结果表明：分别以吗啉、正磷酸、拟薄水铝石为模板剂、磷源和铝源时,合成结晶度相对较高的SAPO-34分子筛的条件为：以正硅酸乙酯为硅源,原料摩尔配比Al2O3：P2O5：SiO2：MOR：H2O=1.0：1.0：0.6：3.0：100,陈化时间2 h,晶化温度200℃,晶化时间48 h。采用水热合成法,通过在合成过程分别添加甲醇等低碳醇助剂和硝酸锌等金属盐类的方法制备了一系列改性SAPO-34分子筛,以甲醇裂解制取低碳烯烃为模型反应,对所制备的分子筛进行了性能评价,并以添加锌为例,采用XRD、BET、NH3-TPD、XPS和FT-IR等表征技术,系统地研究了锌改性对SAPO-34分子筛催化剂的物理化学特性的影响。结果表明：(1)添加甲醇、乙醇、丁醇、乙二醇和丙三醇均可合成出SAPO-34分子筛；但所合成的分子筛对提高总烯烃(C2=+C3=)选择性没有促进作用或促进作用不大。(2)所制备的MeAPSO-34分子筛具有比SAPO-34分子筛更高的乙烯选择性和总烯烃(C2=+C3=)选择性,且Ni-Zn双金属改性比单金属改性更有利于总烯烃(C2=+C3=)选择性的提高,但金属离子的添加会导致丙烯选择性的降低。与SAPO-34相比,单金属Ni的加入可使乙烯的选择性增加7.7%(由SAPO-34的40.7%增加至NiAPSO-34的48.4%),总烯烃(C2=+C3=)选择性增加2.5%；而双金属Ni-Zn的加入可使乙烯的选择性增加6.5%,总烯烃(C2=+C3=)选择性增加3.2%。(3)当晶化液中硝酸锌质量百分含量为0.41%时(所合成分子筛命名为0.41%ZnAPSO-34),可使总烯烃(C2=+C3=)选择性提高4.7%,相对最高。(4)锌进入了SAPO-34分子筛骨架,且引入锌离子可对分子筛的酸性和孔径分布进行调变。以0.41%ZnAPSO-34分子筛催化剂为基础,对甲醇裂解制低碳烯烃的工艺条件进行了研究,确定的相对适宜工艺条件为：温度500℃,水/甲醇质量比5：1,甲醇质量空速3.9 h-1。更多还原

【Abstract】 SAPO-34 zeolites were synthesized by the hydrothermal method and their structures were characterized by means of X-ray powder diffraction (XRD). The effects of Silica source, raw material ratio and synthesis conditions on the crystallinity were investigated. The results showed that: Taking morpholine (MOR), phosphate, pseudo-boehmite as template, phosphorus source and aluminum source, respectively, the crystallinity of SAPO-34 zeolite was better when synthesized at the following conditions: Took TEOS as silicon source, the raw material mole ratio was Al2O3:P2O5: SiO2:MOR:H2O=1.0:1.0:0.6:3.0:100, the aging time was 2 h, the crystallization temperature was 200℃and the crystallization time was 48 h.SAPO-34 zeolite was modified by means of adding alcohol additives such as methanol and metal ions such as zinc nitrate, nickel nitrate and (zinc nitrate + nitrate nickel) in its synthesis, respectively. The catalytic performance of these zeolites was experimentally evaluated taking methanol to olefins (MTO) as the model reaction in a fixed-bed reactor. The effeets of Zn on the physical chemistry characteristics of SAPO-34 zeolite were investigated based on the XRD, XPS, BET, NH3-TPD and FT-IR. The results showed that:(1) Adding methanol, ethanol, butanol, ethylene glycol and glycerol, respectively, all could synthesize SAPO-34 zeolites, but only could increase little of the total olefins (C2=+C3=) selectivity. (2) The MeAPSO-34 (Me=Ni, Zn, Fe, or Ni-Zn) zeolites prepared by adding metal ions when synthesized SAPO-34 had a higher selectivity of ethylene and total selectivity of ethylene and propylene than SAPO-34 zeolite, the total selectivity of ethylene and propylene was higher on Ni-ZnAPSO-34 than on other MeAPSO-34 (Me=Ni, Zn, Fe, Cu) and it was noteworthy that adding metal ions would lead to the decrease of the propylene selectivity. The NiAPSO-34 could make an increase of ethylene selectivity by 7.7% (from 40.7% over SAPO-34 upon to 48.4% over NiAPSO-34) and total selectivity of ethylene and propylene by 2.5%; the Ni-ZnAPSO-34 made an increase of ethylene selectivity by 6.5% and total selectivity of ethylene and propylene by 3.2%. (3) When the mass content of zinc nitrate was 0.41%, the total olefins (C2=+C3=) selectivity increased by 4.7% and was the best. (4) Zn incorporated into the framework of SAPO-34 zeolite, in addition, medium strength acid and appropriate pore size could increase the (C2=+C3=) selectivity.Then the effects of temperature, water/methanol weight ratio and methanol WHSV on MTO process were investigated and the optimal condition was determined as follows:the temperature was 500℃, the water/ methanol weight ratio was 5:1 and the methanol WHSV was 3.9 h-1.更多还原