SAPO-11分子筛改进合成及正十二烷加氢异构化性能

用二乙胺作模板剂,在较短晶化时间的水热条件下合成出不同Si/Al比的SAPO- 11样品。Si/Al比升高,结晶度下降,晶粒变小。~(29)Si NMR谱表明Si/Al比为0. 33的SAPO-11的SAPO区与Si区的交界区明显扩大,与之对应的NH_3-TPD也表明有较 高的中强酸/弱酸比例。样品担载Pd后对正十二烷的加氢异构化反应表明,交界区 扩大的Si/Al = 0.33的样品有最高的加氢异构化得率和选择性。     

DEA-H_2O体系中SAPO分子筛选择性转化

介绍了以二乙胺(DEA)为模板剂,水热合成法合成了SAPO分子筛.采用XRD,SEM,FT-IR,NMR等表征手段系统考察了各种合成条件对SAPO-5和SAPO-34分子筛合成的影响.结果表明,通过调节水热合成条件,S APO-5和SAPO-34可以选择性的形成.DEA加入量、硅含量、陈化时间、晶化时间及Si/Al对产品的结晶度及晶相组成影响较大.较长的晶化时间以及较高的Si/Al有利于合成纯SAPO-34分子筛.相反,较易形成SAPO-5分子筛AFI结构.     

二乙胺导向合成SAPO-34及与其它模板剂的对比

以二乙胺 (DEA) 为模板剂, 合成了 SAPO-34 分子筛, 详细考察了磷酸用量、水用量以及硅源和铝源等因素的影响. 结果表明, 在 0.7 ≤ n(P2O5)/n(Al2O3) ≤ 1.2 及 25 ≤ n(H2O)/n(Al2O3) ≤ 100 范围内, 可以得到纯相 SAPO-34 分子筛, 铝源对所得样品的组成影响较大. 同时, 采用三乙胺 (TEA)、吗啉 (MOR) 以及二乙胺-三乙胺 (DEA-TEA) 混合模板剂合成了 SAPO-34, 通过 X 射线衍射、X 射线荧光分析、扫描电镜、热重和 29Si 固体核磁共振等手段对所得样品进行了表征. 结果显示, 不同模板剂促使硅进入 SAPO-34 骨架的能力顺序为 SAPO-34 (DEA) SAPO-34 (MOR) SAPO-34 (TEA); SAPO-34 骨架中所能容纳的最大 Si(4Al) 含量顺序为 SAPO-34 (DEA) ≈ SAPO-34 (MOR) SAPO-34 (TEA).     

SAPO-34分子筛的合成及甲醇制烯烃催化性能

以三乙胺为模版剂,系统研究了合成凝胶中硅含量、磷酸含量以及水含量对SAPO-34分子筛晶化及其MTO催化性能的影响,Si对SAPO-34的形成具有结构导向作用,只有当SiO2/Al2O3 ≥ 0.25时才可以得到纯相SAPO-34分子筛. 然而随着凝胶中Si含量增大,合成样品中出现氧化铝物种,结晶度、比表面积逐渐下降,催化稳定性降低. 进一步研究发现,凝胶P2O5/Al2O3和H2O/Al2O3比对SAPO-34的合成和催化性能也有很大影响. 当P2O5/Al2O3=1.1,H2O/Al2O3=36时,合成样品具有较高的比表面积、较为理想的(P+Si)/Al比和适宜的酸性,单程寿命达到520 min. 在此基础上研究了焙烧条件对SAPO-34分子筛催化性能的影响,结果表明SAPO-34在流动的空气气氛中焙烧8 h得到的样品比焙烧10 h的样品残留了更多的模版剂,且部分残留的模版剂以二烯烃的形式存在,催化寿命明显比焙烧10 h的样品长,达到580 min.     

不同加铝方式对SAPO-34分子筛合成及MTO催化性能的影响

在水热合成体系中,以三乙胺(TEA)和四乙基氢氧化铵(TEAOH)为混合模板剂,考察了在初始凝胶形成过程中铝源的加入方式对合成SAPO-34分子筛及甲醇制烯烃(MTO)催化性能的影响;通过X射线衍射(XRD)、扫描电子显微镜(SEM)、氮气等温吸附脱附(BET)、²⁹Si固体核磁(²⁹Si MAS NMR)、氨气程序升温脱附(NH₃-TPD)等方法对合成产物进行物性表征,并研究了其在甲醇转化制烯烃(MTO)反应中的催化性能。结果表明,随着首先加铝量的增加,粒径有逐渐变小的趋势,且逐渐出现板层状形貌的SAPO-34分子筛;同时,产物分子筛骨架中Si(4Al)配位结构的数量增加,强酸比例在逐渐增大,且酸密度增加;随着强酸比例和酸密度的提高,SAPO-34分子筛在MTO催化反应中的寿命逐渐延长,丙烯选择性逐渐增大而乙烯选择性逐渐减小。     

骨架富含Si(4Al)结构的SAPO-34分子筛的合成及其对甲醇制烯烃反应的催化性能

通过在初始凝胶中加入HF合成了骨架富含Si(4Al)配位结构的SAPO-34分子筛. 使用X射线衍射、扫描电镜、X射线荧光和核磁共振等表征手段研究了初始凝胶中HF的加入对合成SAPO-34分子筛的晶体结构、晶体形貌、元素组成以及骨架硅配位环境的影响. 结果表明,在初始凝胶中加入F离子后,合成的SAPO-34分子筛的晶体结构更加规整;随着初始凝胶中F离子含量的提高,合成的SAPO-34分子筛晶体骨架中Si(4Al)配位结构的数量增多, Si(nAl)(n=3～0)配位结构的数量减少. 将合成的SAPO-34分子筛催化剂用于甲醇制烯烃反应,结果显示, SAPO-34分子筛骨架中富含Si(4Al)配位结构可以有效提高反应产物中乙烯的选择性,同时能够延长催化剂的寿命.     

改进水热法合成SAPO-11及其酸性和异构化活性

在含异丙醇的体系中,采用程序升温水热法合成了SAPO-11分子筛,并通过X射线衍射、扫描电镜、低温氮物理吸附、氨程序升温脱附、吡啶吸附红外光谱和29Si固体核磁共振等手段进行了表征.结果表明,与常规水热合成法相比,该方法合成的SAPO-11结晶度高,晶粒小,微孔分布集中,酸性强,同时还具有较大的比表面积和微孔孔容.以该分子筛制备的Pt/SAPO-11催化剂在正十四烷临氢异构反应中表现出较高的催化活性和异构选择性.     

杂原子取代型磷酸铝分子筛上丁烯异构化反应

采用水热法合成了Si、Zr杂原子取代的磷酸铝分子筛（APO-11）.研究发现,它们(SAPO-11、ZAPO-11)与APO-11分子筛骨架结构相同（AEL型）；三者表面形貌不同,SAPO-11与APO-11分子筛同为球形颗粒,而ZAPO-11则为棒状晶粒.杂原子的取代能改变APO-11分子筛的酸性质以及微孔分布.反应评价显示,异构化活性SAPO-11>> ZAPO-11 > APO-11；其中SAPO-11分子筛,当Si/Al=0.15时,异构化性能最佳.异构化反应的因子（时间、分压、温度）系统考察发现,主要副产物C3、C5＋与i-C4=的浓度呈现不同的变化趋势,从而证实丁烯选择性异构是通过单分子机理实现的,C3、C5＋是通过双分子历程生成的.     

Al-TS-1的合成及催化氧化性能

系统研究了Al掺杂TS-1(Al-TS-1)分子筛的合成及其催化氧化性能,采用X射线衍射、紫外-可见光谱、电感耦合等离子体发射光谱、扫描电镜、²⁷Al和²⁹Si固体核磁共振等手段对Al-TS-1样品进行了表征.结果表明,在合成过程中,Al的引入会影响TS-1中骨架Ti的形成,但当Al含量低于一定值(Al/Si≤0.005)时,其影响很小.Al-TS-1中骨架Al和骨架Ti均不对其相应的酸催化和催化氧化作用产生影响.骨架Al抑制了Al-TS-1在碱性应用体系中的与Ti相邻Si的溶脱,从而保护了骨架Ti活性中心.     

模板剂对SAPO-11的物化及异构性能的影响

采用水热合成法,以二正丙胺（DPA）和二异丙胺（DIPA）混合物为模板剂合成SAPO-11分子筛,考察了模板剂用量和混合模板剂中DPA和DIPA配比对所得产物的影响,并通过XRD、N2吸附、NH3 TPD和29Si MAS NMR等手段对样品进行了表征。结果表明,改变模板剂用量和配比不仅可以调节SAPO-11结晶度,还会改变Si在分子筛骨架上的分布,从而调节SAPO 11的酸性。当模板剂用量比为1.5,模板剂中DPA的质量分数为66％时,样品的Si区面积最小,Si（n Al）（0 < n < 4）结构最多。因此,分子筛酸性和对正十四烷异构活性也最高。     

Effect of the template on synthesis of SAPO-11 for hydroisomerization of n-octane

Summary In this study, five typical dialkylamines with different alkyl chains were tested as template for synthesis of SAPO-11. Among these templates, diethylamine, dipropylamine and diisopropylamine have been shown to be effective for synthesis of SAPO-11. SAPO-11 synthesized with dipropylamine in the gels of high Si content and diisopropylamine in the gels of low Si content exhibit good catalytic performance in hydroisomerization of n-octane.     

Formation of small pore SAPO-44 type molecular sieve

The hydrothermal transformation of silico–aluminophosphate gel with cyclohexylamine to SAPO-44 has been examined. The hydrothermal crystallisation products of the SAPO have been investigated by X-ray diffraction, FTIR, nitrogen and water adsorption, thermogravimetric analysis, surface analysis and ²⁷Al, ³¹P, and ²⁹Si MAS NMR. Structural changes were observed in the silico–aluminophosphate gel with and without organic template and during the hydrothermal crystallisation. The silico–aluminophosphate gel converted to pure SAPO-CHA phase in 168 h at 473 K. The surface of SAPO-44 was silicon rich as compared with that of SAPO-34 and SAPO-18. The ²⁷Al MAS NMR signal of tetrahedrally coordinated Al observed in the silico–aluminophosphate gel without the organic template was changed to octa-, penta- and tetrahedrally coordinated aluminium upon the addition of the cyclohexylamine template to the SAPO gel. After 3 h of hydrothermal treatment at 473 K however, the ²⁷Al MAS NMR signals of the octahedral and pentacoordinated aluminium were removed. This was also confirmed by ³¹P and ²⁹Si MAS NMR. The tetrahedrally coordinated P and Si were detected within 3 h at 473 K. The sorption capacity and adsorption–desorption trends of the SAPO gels and the crystallisation products were found to be different. ²⁹Si MAS NMR results indicated that the percentage of Si (4Al) and its distribution were significantly affected by the crystallization period. SAPO-44 was thermally stable up to 973 K with phase change observed over the calcination temperature of 1193 K. The SAPO gels and the crystallisation products have also been investigated for their catalytic behaviour in n-hexane and ethanol conversion reactions.     

Catalytic behavior in skeletal isomerization of linear butenes and acidic properties of ani-Pr2NH-templated sapo-11 molecular sieve

SAPO-11 samples were synthesized withi-Pr₂NH as a novel template, and applied in catalytic skeletal isomerization of linear butenes. More linear butenes were converted with increasing Si content in SAPO-11 samples, while theiso-butene selectivity was proportional to the Si content only in the lower reaction temperature region. The maximum yield ofiso-butene was achieved around 763 K. The acidic properties of SAPO-11 samples were studied by NH₃-TPD and IR spectroscopy. The strong acidity was due to the formation of Si domains in the framework lattice.     

Hydrothermal Synthesis of Silicoaluminophosphate with AEL Structure Using a Residue of Fluorescent Lamps as Starting Material

Silicoaluminophosphate molecular sieves of SAPO-11 type (AEL structure) were synthesized by the hydrothermal method, from the residue of a fluorescent lamp as a source or Si, Al, and P in the presence of water and di-propyamine (DPA) as an organic template. To adjust the P₂O₅/SiO₂ and Si/Al and ratios, specific amounts of silica, alumina, or alumina hydroxide and orthophosphoric acid were added to obtain a gel with molar chemical composition 1.0 Al₂O₃:1.0 P₂O₅:1.2 DPA:0.3 SiO₂:120 H₂O. The syntheses were carried out at a temperature of 473 K at crystallization times of 24, 48, and 72 h. The fluorescent lamp residue and the obtained samples were characterized by X-ray fluorescence, X-ray diffraction, scanning electron microscopy, and BET surface area analysis using nitrogen adsorption isotherms. The presence of fluorapatite was detected as the main crystalline phase in the residue, jointly with considered amounts of silica, alumina, and phosphorus in oxide forms. The SAPO-11 prepared using aluminum hydroxide as Al source, P₂O₅/SiO₂ molar ratio of 3.6 and Si/Al ratio of 0.14, at crystallization time of 72 h, achieves a yield of 75% with a surface area of 113 m²/g, showing that the residue from a fluorescent lamp is an alternative source for development of new materials based on Si, Al, and P.     

SAPO-11分子筛的合成

以二正丙胺(DPA)为模板剂、利用水热法合成SAPO-11分子筛，系统考察了硅源、硅含量、模板剂用量以及晶化条件（晶化温度、时间以及pH值）对SAPO-11分子筛合成的作用。研究结果表明：硅源是决定SAPO-11分子筛合成及结构的关键组分之一，其释放出活性硅物种的速率要与磷酸铝分子筛的前驱体生成的速度相一致；酸性硅溶胶是合成SAPO-11的合适硅源；在SiO2/Al2O3=0～0.7，DPA/P2O5=0.8～1.8，pH=5.8～7.8条件下，可合成纯SAPO-11分子筛。此外，SAPO-11分子筛的合成，还存在明显的诱导期以及晶型的转化过程。在合成条件下，晶化时间4?h时，SAPO-11开始晶化，至24 h，SAPO-11分子筛可晶化完全。继续延长晶化时间，SAPO-11分子筛与SAPO-31分子筛之间发生转晶现象。     

新型磷酸硅铝分子筛SAPO-56的合成与表征

以N,N,N',N'-四甲基-1,6-己二胺(TMHD)为模板剂,采用水热法在Al₂O₃-P₂O₅-SiO₂体系中合成了SAPO-56分子筛.固定模板剂和水,得到Al-Si-P三元体系相图.当原料物质的量比为0.52)/n(M)<0.7(M=SiO²⁺Al₂O³⁺P₂O₅),0.152O₃)/n(M)<0.4及0.12O₅)/n(M)<0.3时,出现SAPO-56合成的纯相区.固定合成凝胶中硅、铝、磷和水的量,模板剂的用量改变对合成影响较大.n(TMHD)/n(P₂O₅)≥2时,产物是纯SAPO-56.用XRD,SEM,IR,DTA-TG和吸附等方法研究了产物的物化性能.结果表明,SAPO-56分子筛具有较好的热稳定性(骨架坍塌温度为1150℃)和较大的水吸附量(41%).SAPO-56分子筛催化剂对甲醇转化制烯烃反应表现出了良好的催化活性和较高的C₂和C₃烯烃选择性.     

Achieving highly selective CO2 adsorption on SAPO-35 zeolites by template-modulating the framework silicon content

Small-pore silicoaluminophosphate (SAPO) zeolites with 8-ring pore windows and appropriate acidities/polarities, for example, SAPO-34 (CHA) and SAPO-56 (AFX), have proven to be potential adsorbing materials for selective adsorption of CO₂. However, SAPO-35 zeolites (LEV framework topology) synthesized using conventional templates are less reported for highly selective CO₂ adsorption which might be due to inappropriate Si contents and acidities in the framework. In this work, by using N-methylpiperidine (NMP) as a template, SAPO-35 zeolites with various Si contents were synthesized under hydrothermal conditions, which allowed SAPO-35 zeolites with modulated acidities and polarities. The CO₂ adsorption and separation properties of SAPO-35_x (x: Si/(Si + P + Al) in molar ratio) were investigated, and a close relationship between the acidity, polarity and CO₂ adsorption and separation capacity was revealed. SAPO-35_0.14 with the strongest acidity showed the highest CO₂ uptake of 4.76 mmol g⁻¹ (273 K and 100 kPa), and appeared to be one of the best SAPO materials for CO₂ adsorption. Moreover, increased Brønsted acidity can significantly enhance the adsorption selectivity of CO₂ over N₂. At 298 K and 100 kPa, SAPO-35_0.14 showed the highest CO₂/N₂ selectivity of 49.9, exhibiting potential for industrial processes. Transient binary breakthrough experiments on SAPO-35_0.14 further proved the efficient separation performance and stable circulation. The results of this study prove that the framework Si content of SAPO-35 zeolites is essential for regulating their CO₂ adsorption performance. This work demonstrates that modulating the silicon content and acidity in SAPO zeolites via a suitable choice of template, as well as polarity, is of great significance for the rational synthesis of zeolites with superior CO₂ adsorption and separation abilities.

SAPO-35 zeolite with template-modulated framework Si content showed superior CO₂ affinity and separation of CO₂/N₂ mixtures.