偏高岭土水热合成磷酸硅铝分子筛及其表征

以具有一定活性的偏高岭土兼作铝源与硅源、正磷酸作磷源、三乙胺和氧氟酸为复合模板剂,用水热方法合成了磷酸硅铝分子筛(SAPO-5).利用X射线衍射分析、红外光谱分析、扫描电镜、Brunauer-Emmett-Teller分析等手段对产物进行了表征.研究了不同晶化时间对产物晶相组成的影响.在473 K下,晶化时间为24 h时,可得到结晶度较高的SAPO-5晶体,其形貌为尺寸大约200 nm的柱状晶体,比表面积为205.9 m2/g,平均孔径为9.72 nm,孔容为0.73 cm3/g,属于介孔材料.     

偏高岭土水热合成SAPO-5分子筛影响因素研究

以具有一定活性的偏高岭土兼作铝源与硅源、正磷酸作磷源、三乙胺作模板剂,水热法合成了SAPO-5分子筛。考察了晶化时间、三乙胺用量、HF的添加、体系中水含量等因素对产物晶相组成及结构的影响。利用X射线衍射分析（XRD）、红外光谱分析（FTIR）、扫描电镜（SEM）、X光电能谱（XPS）等手段对产物结构与组成进行了表征分析,研究结果表明原料最佳配比为MK：P2O5：2.5TEA：0.1HF：45H2O,在200℃下,晶化24h可获得结晶度较高、晶体形貌规整的SAPO-5分子筛。     

硅源用量对SAPO-18分子筛合成及催化性能的影响

采用水热合成法,以N,N-二异丙基乙胺为模板剂合成SAPO-18分子筛,并用X射线衍射、X射线荧光光谱、扫描电子显微镜、NH3程序升温脱附及N2吸附-脱附等对其结构进行表征,系统研究合成凝胶中硅源用量对SAPO-18分子筛合成及其在甲醇制烯烃反应中催化性能的影响。结果表明,在晶化温度453 K、晶化时间96 h和合成凝胶中0.3≤n(Si O2)∶n(Al2O3)≤1.2条件下,能合成出纯相的SAPO-18分子筛,其中,当n(Si O2)∶n(Al2O3)=0.6,在反应时间135 min时,合成的SAPO-18分子筛具有较高的双烯选择性(乙烯+丙烯)。合成凝胶中硅源的用量对SAPO-18分子筛酸性有显著影响,适当增加分子筛中强酸比有助于提高乙烯和丙烯选择性,但缩短催化剂寿命。     

SAPO-34分子筛形貌和粒径的影响因素考察

以四乙基氢氧化铵为模板剂,水热合成法制备SAPO-34分子筛,采用XRD和SEM进行表征,考察硅铝比、晶化温度、晶化时间和陈化时间对分子筛形貌和粒径的影响。结果表明,在硅铝物质的量比为0.8、晶化温度200℃、晶化时间24 h和陈化时间4 h条件下,可合成晶粒均匀和晶体表面光滑的粒径仅为2μm的SAPO-34分子筛。     

影响SAPO-5分子筛合成的因素研究

以三乙胺为模板剂合成了SAPO-5分子筛，并系统地研究了各种合成条件对SAPO-5分子筛合成的影响。结果表明，晶化液原料配比、硅铝比、模板剂用量、加料顺序及水含量对SAPO-5分子筛的结晶度和稳定性都有重要影响，n（SiO2）／n（Al203）=1．5和／n（H2O）／n（Al2O3）=40为SAPO-5合成的适宜条件，此时晶化产物的结晶度高，稳定性好。     

模板剂法水热合成高硅铝比ZSM-5分子筛

以工业水玻璃和硫酸铝为主要原料,正丁胺为模板剂,利用水热法合成出了高硅铝比ZSM-5分子筛。考察了晶化时间、晶化温度、投料硅铝比、合成体系pH值以及模板剂用量等因素对晶化产物的影响。采用X射线衍射、傅里叶变换红外光谱、低温氮气吸脱附、核磁共振、扫描电子显微镜等手段对合成样品进行了表征。结果表明:合成ZSM-5分子筛最适宜的条件为:晶化时间36h,晶化温度170℃,投料硅铝比200,合成体系的pH=11.0,模板剂加入量为模硅比0.2。在最适宜条件下合成得到的ZSM-5分子筛产物具有高的相对结晶度,BET比表面积为335m2/g,晶粒尺寸约为5μm×15μm,骨架硅铝比大于100。     

用富含介孔的硅基材料合成微孔-介孔复合分子筛

以富含介孔的硅基材料为硅源,四乙基氢氧化铵为模板剂,NaAlO2为铝源,调节投料硅铝的摩尔比(n(SiO2)/n(Al2O3)),通过半固相原位合成法,制备了具有不同晶型的微孔-介孔复合分子筛。采用X射线衍射仪分析样品组成,扫描电镜观测样品晶体形态,使用容量吸附分析仪测量样品孔结构。结果表明,所得样品具有微孔-介孔复合结构,在较低硅铝摩尔比条件下(n(SiO2)/n(Al2O3)=20~50),产物主要为β微孔-介孔复合分子筛;硅铝摩尔比较高时(n(SiO2)/n(Al2O3)200),合成产物为ZSM-5微孔-介孔复合分子筛。     

煤系高岭土水热合成介孔材料

以煤系高岭土为硅源,十六烷基三甲基溴化铵（CTABr）为模板剂,水热合成得到介孔材料。并用傅里叶变换红外光谱（FTIR）、扫描电子显微镜（SEM）、高分辨透射电子显微镜（HRTEM）和N2吸附脱附等测试手段对产物进行表征。结果表明合成的介孔材料骨架上具有Si—O、Si—OH和Si—O—Si等介孔材料特征结构,材料BET比表面积为1070 m2/g,孔径分布在3.82 nm处出现峰值。     

介孔SAPO-11分子筛的制备及应用

综述了介孔SAPO-11分子筛的合成机理、制备方法及应用。介绍了介孔SAPO-11分子筛的合成机理,液晶模板机理和协同作用机理,在不同模板剂与无机硅源的静电作用或相互作用下形成液晶结构,移除液晶后,形成介孔孔道。SAPO-11分子筛属于微孔型(<2 nm)磷酸硅铝分子筛,通过模板法、后处理法和分子筛硅源法等制备方法得到的介孔SAPO-11分子筛结晶度良好,孔径和比表面积均增大,有利于大分子反应物进入其孔道和产物溢出。     

晶化时间对SAPO-34分子筛粒径的影响

以硅溶胶为硅源、异丙醇铝为铝源、磷酸为磷源、三乙胺为模板剂,按摩尔比n(Al2O3)∶n(P2O5)∶n(SiO2)∶n(TEA)∶n(H2O)=1∶1∶0.8∶3∶60配制初始反应液。利用水热法合成SAPO-34沸石分子筛,考察了水热晶化时间对沸石晶粒的影响。结果表明,随着晶化时间的延长,合成的SAPO-34产物结晶度随之升高,平均粒径及粒径分布范围也随之变大。     

Influence of template on Si distribution of SAPO-11 and their performance for n-paraffin isomerization

SAPO-11 molecular sieves were synthesized using single agent (i.e. diethylamine (DEA), di-iso-propylamine (DIPA) and di-n-propylamine (DPA)) or a mixture of DEA and DIPA (named DEPA) as the template under hydrothermal conditions. XRD indicated that the directing effect of different templates for AEL structure decreased in the order of DEPA > DPA > DIPA > DEA. ²⁹Si MAS NMR showed that although all SAPO-11 samples synthesized at same Si content, that prepared with the mixed template contained more Si (4Al) sites, whereas Si (nAl, 4-nSi, 0 < n < 4) environments were predominant in the samples synthesized with single template. The results indicated that the mixed template led to a better Si dispersion and then increased the number of total acid sites of SAPO-11. In the isomerization of n-tetradecane over different Pt/SAPO-11 catalysts, the sample prepared with DEPA showed high catalytic activity and selectivity for i-C₁₄, which were related to the most abundant weak acid sites of the sample.     

Direct Synthesis of a Fluidizable SAPO-34 Catalyst for a Fluidized Dimethyl Ether-to-Olefins Process

The dimethyl ether to olefins process is very important for converting coal to chemicals. A SAPO-34 molecular sieve with a particle size up to 50 μm has been synthesized with morpholine as the template. The cold model fluidization experiment indicates that the SAPO-34 catalyst with average size of 45–50 μm is of good fluidization properties. After high temperature steam treatment at 1073 K for 8 h, this large fluidizable catalyst showed good reactivity and selectivity for the dimethyl ether to olefins (DTO) reaction in a micro-reactor. X-ray diffraction characterization showed that the structure of the catalyst was maintained well. A fluidized reactor of 50 mm inner diameter was used to carry out the DTO reaction, which showed that the fluidizable SAPO-34 is a selective catalyst for light olefin production.     

升温速率和晶化模式对固相转化合成SAPO-5的影响

固相转化法有利于合成硅取代型磷酸铝分子筛(SAPO-5)。采用XRD、SEM、EDS表征方法研究了升温速率和晶化模式对SAPO-5分子筛结构的影响。结果表明,在高升温速率(140℃·h^-1)和低升温速率(5.8℃·h^-1)下能合成出纯SAPO-5分子筛,在中等升温速率(17.5～70℃·h^-1)下则有SAPO-34分子筛与SAPO-5伴生。此外,晶化模式对SAPO-5分子筛的形貌有显著影响。在中等升温速率下,动态晶化形成的SAPO-5分子筛为球形,静态晶化则为六边形片状,但Si的取代机制均可能为SM3取代。在高升温速率和低升温速率下,晶化模式不影响SAPO-5分子筛的形貌。而Si在动态晶化时为SM2取代,静态晶化时为SM3取代。     

Isomerization of n-butane to isobutane over Pt-SAPO-5, SAPO-5, Pt-H-mordenite and H-mordenite catalysts

Aluminium sulphate, sodium aluminate, aluminium oxide and pseudo-boehmite were used as sources of aluminium in the synthesis of SAPO-5. The samples were characterized using XRD, SEM, XRF, FTIR and nitrogen adsorption. The formation of SAPO-5 phase, morphology, surface area and catalytic properties were found to be influenced by the source of aluminium used in the synthesis. The sample synthesized using pseudo-boehmite as a source of aluminium showed most phase pure silicoaluminophosphate, whereas syntheses using aluminium phosphate or sodium aluminate only formed quartz and berlinite. The FT-IR spectra exhibited the presence of Brønsted and Lewis acid sites in the Pt-SAPO-5, SAPO-5, Pt-H-mordenite and H-mordenite catalysts. Modification of SAPO-5 and mordenite by Pt impregnation did not influence the structures of these catalytic materials. The Pt-H-mordenite and H-mordenite catalysts with stronger Brønsted acidity exhibited higher conversion of n-butane and yield to isobutane than Pt-SAPO-5 and SAPO-5 catalysts with weak acid sites. Introduction of Pt in SAPO-5 and mordenite played a positive role in the isomerization of n-butane to isobutane.     

Synthesis, Characterization and Hydroisomerization Performance of SAPO-11 Molecular Sieves with Caverns by Polymer Spheres

Silicoaluminophosphates SAPO-11 molecular sieves with caverns were synthesized using polystyrene (PS) micro-spheres as template. The morphologies of the cavitary SAPO-11 molecular sieves exhibit spherical particles ranging 7–10 μm aggregated from cubic plate microcrystallites which just like the SAPO-11 molecular sieves synthesized with the conventional method, but some caverns of 500–1,200 nm pore size in diameter can be observed on the former material. The strength and distribution of the acid sites of the cavitary SAPO-11 are similar to that of the conventional SAPO-11, but the acid density is slightly low owing to the decreased crystallinity of the cavitary SAPO-11. The micropores size and mesopores size of the conventional SAPO-11 are centered at about 0.45 and 3.8 nm, respectively, while the cavitary SAPO-11 has, in addition to the micropores and mesopores, large mesopores ranging 5–30 nm and macropores ranging from about 100 to 1,200 nm, which were derived from the PS sphere template. Hydroisomerization of n-hexadecane was performed to investigate the catalytic performance of the cavitary SAPO-11. The result showed that, in comparison with the conventional SAPO-11, the cavitary SAPO-11 has high activity based on per active site and high selectivity, owing to the fast diffusion of the reactant and isomer products inside the catalyst.     

伊利石合成磷酸硅铝分子筛及其表征

采用碱熔活化方法对伊利石进行活化,系统地考察了煅烧温度、煅烧时间、矿物粒度、矿碱质量比等条件对伊利石活化的影响;以活化伊利石为主要硅、铝源,采用水热法合成磷酸硅铝分子筛（SAPO-11）,系统地考察模板剂种类、模板剂用量、投料硅铝物质的量比、晶化温度等合成条件对产物结构和性质的影响。利用X射线衍射（XRD）、N₂吸附-脱附、扫描电镜（SEM）和透射电镜（TEM）等分析手段对活化产物和合成的分子筛进行了分析表征,结果表明,伊利石的最佳碱熔活化条件为煅烧温度为800 ℃、煅烧时间为90 min、伊利石矿粒径为75 μm、矿碱质量比为1∶0.8,经活化后伊利石的晶型结构基本完全被破坏,活化产物主要是高活性的低聚合态硅铝酸盐,化学反应活性较高;在原料配比为n（三氧化二铝）∶n（五氧化二磷）∶n（模板剂）∶n（二氧化硅）∶n（水）=1∶1∶1∶0.5∶50、水热晶化温度为190 ℃、晶化时间为24 h时成功合成结晶度较高的纯相SAPO-11分子筛,合成的SAPO-11分子筛具有较大的比表面积,样品主要由粒径为1~3 μm的椭球状颗粒组成,该合成方法丰富了磷酸硅铝（SAPO）分子筛的原料来源,拓展了中国伊利石的高附加值利用途径。     

硅含量对氯甲烷制取低碳烯烃的SAPO-34分子筛酸性的影响

以三乙胺-四乙基氢氧化铵为复合模板剂,合成了不同硅含量的SAPO-34分子筛,并采用XRD、NH₃-TPD、以及²⁹Si MASNMR等方法对其进行了表征,最后考察了不同硅含量SAPO-34分子筛催化转化氯甲烷制取乙烯、丙烯的反应性能。结果表明:硅铝比在0.10~0.80时,均能合成规整的SAPO-34立方晶粒;硅铝比低于0.05或高于1.00时,易伴随形成片状和无定形晶相。当硅铝比为0.6时,SAPO-34的结晶度最大,微孔比表面积为588m²/g,微孔体积为0.267cm³/g。硅铝比从0.05到0.60逐渐增大时,SAPO-34酸强度和酸数目明显增多,继续增大硅铝比,酸强度增强,弱酸数目减少。在T=425℃、氯甲烷WHSV=2.73h^-1时,对所合成SAPO-34分子筛催化氯甲烷的反应性能进行了评价,随硅铝比增大,SAPO-34的酸性增强,氯甲烷的初始转化率逐渐升高,然而二次反应加剧致使乙烯丙烯选择性略有下降。     

纳米薄层SAPO-5分子筛的离子热合成及催化性能

以小剂量的丁二酸、氯化胆碱和四乙基溴化铵复配形成的低共熔混合物为溶剂和模板,以水热法合成的纳米薄层SAPO-5分子筛作为晶种,使用离子热法在微波加热功率为400 W、温度为180℃和晶化时间为20 min的条件下,高效合成了具有六角花瓣状的纳米薄层SAPO-5分子筛。采用XRD、SEM、N2物理吸/脱附和NH3-TPD对合成样品的物相、形貌、孔结构和酸性进行了分析。结果表明,所合成的样品SC2-T180-t20-P400是一种同时含有微孔-介孔-大孔结构的多级孔SAPO-5分子筛,其外表面积高达85m2/g。分子筛产物中无机物的原子利用率达到88%。该样品在苯与苯甲醇的烷基化反应中,苯甲醇转化率和二苯甲烷选择性分别达到99.9%和94.0%,表现出比传统水热法合成的纳米薄层SAPO-5催化剂更为优异的催化性能。     

Effect of different TEAOH/DEA combinations on SAPO-34’s synthesis and catalytic performance

SAPO-34 molecular sieves were synthesized hydrothermally using different combinations of amine agents [i.e., tetraethyl ammonium hydroxide (TEAOH) and diethylamine (DEA)]. XRD indicated the good crystallinity directed by single or mixed template for CHA structure. The morphology of crystals from SEM photograph was shown to be cubic shape of typical SAPO-34, but distinct in crystal size, increasing from 0.3–0.8 to 3.1–9.1 μm with the amount of DEA in the gel. NH₃-TPD showed similar acid properties for SAPO-34 with TEAOH content from 1.0 to 0.1, but strong acidity synthesized with DEA only. ²⁹Si MAS NMR demonstrated that Si species in framework with single DEA existed in large size of silicon islands, whereas dispersed finely in siliceous islands of smaller size with remarkable Si (nAl, 4-nSi, 0 < n < 4) environments in the samples using mixed template. In the methanol conversion to olefins over different SAPO-34 catalysts, the sample prepared with the mixtures of 50%TEAOH and 50%DEA showed the longest lifetime and high selectivity to C₂⁼~C₃⁼.     

The catalytic performance of methylation of naphthalene with methanol over SAPO-11 zeolites synthesized with different Si content

A series of SAPO-11 zeolites with different Si contents were prepared by hydrothermally synthesized method. They were characterized by ICP, XRD, SEM, FT-IR, N₂ adsorption-desorption, NH₃-TPD and ²⁹Si MAS NMR, and evaluated by the methylation of naphthalene with methanol to 2,6-dimethylnaphthalene (2,6-DMN). According to XRD and SEM results, the crystallinity of SAPO-11 sample increased with increase of the Si content until the SiO₂/Al₂O₃ ratio was up to 0.2. However, a reduction in the crystallinity was observed with further increase of the Si content of the synthesis. N₂ adsorption-desorption results showed that all the samples possessed micropores and secondary mesopores. SAPO-11 sample with SiO₂/Al₂O₃ ratio of 0.2 exhibited the largest secondary mesopores size distributions. NH₃-TPD and ²⁹Si MAS NMR showed that the Si content was incorporated into the framework affecting not only the acid sites but also the acid strength of SAPO-11. SAPO-11 with SiO₂/Al₂O₃ ratio of 0.2 presented the high catalytic performances for the methylation of naphthalene, which was mainly attributed to the amount of secondary mesopores in the SAPO-11 zeolite.