间歇式水热合成制备丝光沸石膜及其异丙醇脱水应用

采用市售廉价大孔α-Al₂O₃管作为基质材料，通过热浸渍法在管外表面涂敷晶种，随后在无模板剂体系下，利用新型的间歇式水热合成法制备丝光沸石膜。对比了传统加热和间歇式加热对丝光沸石膜形貌、结构及渗透蒸发异丙醇脱水分离性能的差异。考察了合成液中Na₂O/SiO₂、SiO₂/Al₂O₃和NaF/SiO₂物质的量之比在间歇式水热合成下对丝光沸石膜的影响。研究结果表明，当合成液中Na₂O/SiO₂、SiO₂/Al₂O₃和NaF/SiO₂物质的量之比分别为0.24、16.7和0.25时，制备的丝光沸石膜渗透蒸发异丙醇脱水分离性能最佳，在75℃下，对异丙醇/水(9∶1，w/w)的渗透通量达5.60 kg·m^-2·h^-1，水对异丙醇的分离因数大于10 000。     

斜发沸石的合成研究

采用水热法，分别在物质量的比为2.1Na₂O∶10SiO₂∶Al₂O₃∶110.1H₂O和1.05K₂O∶1.05Na₂O:12SiO₂∶Al₂O₃∶250H₂O的条件下合成出较高纯度斜发沸石，研究了斜发沸石合成的各种影响因素。结果表明，在140、160和180 ℃条件下均能合成出斜发沸石，且提高温度可以缩短斜发沸石的晶化时间；反应混合物的硅铝物质量的比应控制在10～12之间；碱度的降低会导致晶化时间延长，过高的碱度则导致晶种溶解；反应混合物中K⁺的存在利于斜发沸石的晶化。合成斜发沸石对海水中K⁺饱和吸附量达 38.60 mg·g^-1以上，其吸附性能显著优于文献报导的天然斜发沸石。     

无有机模板剂水热合成Co同晶取代的丝光沸石分子筛

在硅酸钠、硫酸铝、硝酸钴和氢氧化钠的全无机体系条件下, 采用无有机模板剂水热法合成了Co同晶取代的丝光沸石分子筛. 通过粉末X射线衍射(XRD)、扫描电子显微镜(SEM)、电感耦合等离子体(ICP)光谱、氮气吸附、紫外-可见(UV-Vis)光谱、热重(TG)分析等手段对所得固体产物的织构性质以及钴在分子筛中的存在状态进行了表征. 结果表明, 该方法成功地将Co离子引入到丝光沸石分子筛的骨架结构中, 未发现骨架外Co物种. 典型的合成条件为n(Co)/n(SiO₂) =0.01-0.04, n(SiO₂)/n(Al₂O₃) =20-50, n(H₂O)/n(SiO₂) =40, n(Na₂O)/n(SiO₂)=0.4, 晶化温度170 °C, 晶化时间3-7 d. 讨论了Na+离子在无有机模板剂合成中的结构导向作用. 全无机体系合成得到的产物无需进行传统的高温煅烧处理, 即可获得开放的微孔孔道, 实现了低成本、低能耗、环境友好的Co-丝光沸石的合成.     

缓冲体系中高热和水热稳定性的MCM-48介孔分子筛的合成

利用混合阳离子-非离子表面活性剂为模板剂在缓冲体系中成功地合成出具有高热和水热稳定性的MCM-48介孔材料. 通过XRD, N₂吸附-脱附, ²⁹Si MAS NMR和 ³¹P MAS NMR等手段对样品进行了表征. 结果表明, 合成的MCM-48材料具有高的比表面积和高度有序的孔道系统. 样品在空气中于900 ℃下焙烧15 h和在600 ℃ 100%水蒸气下处理8～10 h, 仍能保持良好的立方孔道结构, 显示很高的热稳定性和极好的水热稳定性.     

高硅无铝Mo-Beta沸石的合成与结构表征

用水热晶化法合成了无铝Mo-Beta沸石,讨论了合成条件对无铝Mo-Beta沸石晶化的影响,通过化学分析、XRD、IR、DTA/TGA、TEM、NMR、ICP和UV-Vis紫外漫反射光谱测定了样品的n(SiO₂)/n(MoO₃)比,并对其结构进行了表征,结果表明,所合成的Mo-Beta沸石晶粒均匀,Mo存在于沸石骨架中,由于Mo的掺入,引起Beta沸石红外光谱、差热分析曲线及晶胞参数, ²⁹SiMASNMR谱等发生变化。     

硅源量和晶化时间对SAPO-34分子筛结构和性能的影响

以吗啡啉为模板剂合成了SAPO-34分子筛，研究了晶化液SiO₂/Al₂O₃比(硅源量)的影响。当SiO₂/Al₂O₃ ≥ 0.6时，能合成出纯净的SAPO-34分子筛;SiO₂/Al₂O₃=1.0时，分子筛骨架中出现“硅岛”结构，此时合成的分子筛样品具有最高的(乙烯+丙烯)选择性。继续增大硅铝比对(乙烯+丙烯     

MCM-48介孔材料相转化合成的形成机制

利用水热合成的方法,使用新型的表面活性剂十六烷基三甲基对苯磺酸盐作为模板剂合成了高质量的MCM-48介孔分子筛,并用X-射线衍射(XRD)、扫描电镜(SEM)、高分辨透射电镜(HRTEM)以及N₂吸附-脱附进行了表征。合成过程的研究表明该合成体系经历了三相,起始相为具有六方对称性的MCM-41,随着加热时间的延长,生成了具有立方对称性的MCM-48,进一步延长加热时间则生成了层状相MCM-50。三相转变发生的核心驱动力来自于表面活性剂有效堆积参数g因子的改变,随着反应时间的延长,由于对甲基苯磺酸根离子（Tos^-）的流失,表面活性剂极性头所占的有效面积（a₀）明显减小,g值变大。另外,XRD、傅立叶变换的红外光谱(FT-IR)以及固体魔角自旋核磁共振(²⁹Si MAS NMR)的表征结果证明：随着晶化时间的延长,相转变的同时伴随着介孔材料的孔壁逐渐由原子无序的非晶态向原子有序的晶态结构转变。最终形成的原子有序层状介孔分子筛可以作为扩孔型微孔分子筛合成的有效前驱体。     

Cr-β沸石的合成与催化性能研究

在SiO₂-Cr₂O₃-(TEA)₂O-Na₂O-H₂O体系中，以四乙基氢氧化铵(TEAOH)为模板剂合成了Cr-β沸石，用XRD、IR、SEM及DTA-TGA等方法对样品进行了表征，探讨了反应混合物组成对Cr-β沸石晶化的影响，初步考查了Cr-β沸石催化苯酚与过氧化氢的羟基化反应活性。     

MCM-48介孔材料相转化合成的形成机制

利用水热合成的方法,使用新型的表面活性剂十六烷基三甲基对苯磺酸盐作为模板剂合成了高质量的MCM-48介孔分子筛,并用X-射线衍射(XRD)、扫描电镜(SEM)、高分辨透射电镜(HRTEM)以及N₂吸附-脱附进行了表征。合成过程的研究表明该合成体系经历了三相,起始相为具有六方对称性的MCM-41,随着加热时间的延长,生成了具有立方对称性的MCM-48,进一步延长加热时间则生成了层状相MCM-50。三相转变发生的核心驱动力来自于表面活性剂有效堆积参数g因子的改变。另外,XRD、傅立叶变换的红外光谱(FT-IR)以及固体魔角自旋核磁共振(²⁹Si MAS NMR)的表征结果证明：随着晶化时间的延长,相转变的同时伴随着介孔材料的孔壁逐渐由原子无序的非晶态向原子有序的晶态结构转变。最终形成的原子有序层状介孔分子筛可以作为扩孔型微孔分子筛合成的有效前驱体。     

A novel method for synthesis of mesoporous ZSM-5 from iron ore tailings

Mesoporous ZSM-5 was prepared from iron ore tailings (IOT) using a two-step process. Mesoporous MCM-41 was first synthesized using cetyltrimethylammonium bromide (CTAB) as mesoporous template and IOT as silica source. The CTAB in the as-synthesized MCM-41 was used as the mesoporogen to produce the mesoporous ZSM-5, by recrystallizing the amorphous walls of MCM-41 with tetrapropylammonium bromide (TPABr) as the structure-directing agent via solid-phase conversion. To evaluate the textural properties of mesoporous ZSM-5, the as-synthesized samples were characterized using x-ray diffraction, scanning electron microscopy, transmission electron microscopy, ²⁹Si, ²⁷Al magic angle spinning nuclear magnetic resonance spectroscopy, and nitrogen adsorption. The results show that phase separation between the surfactant and zeolite crystals was avoided in the solid-phase conversion process, which transforms the as-synthesized MCM-41 to mesoporous zeolite. Therefore, the synthetic route presented herein provides a novel method for the synthesis of mesoporous ZSM-5 from IOT.

     

催化剂量甘油对THF-FER沸石结晶过程的加速作用

The hydrothermal crystallization of THF-FER zeolite was investigated in the reactant system of Na2O-SiO2-Al2O3-H2O with tetrahydrofuran （THF） as the template in the presence of various catalytic amount of glycerol [CH2（OH）CH（OH）CH2（OH）, Glyc] in the temperature range of 413--473 K. Powder X-ray diffraction （XRD） was used to observe the crystallization process, and scanning electron microscope （SEM）, ^13C cross polarization （CP） and ^27Al magic angle spinning nuclear magnetic resonance （MAS NMR）, X-ray fluorescence scattering spectroscopy （XRF）, thermal analysis and nitrogen sorption were used to characterize the zeolite synthesized in the reactant system with Glyc. The catalytic amount of Glyc could promote the crystallization of FER zeolite, to result in lowering the reaction temperature, shortening the period of the zeolite crystallization and effectively restraining cocrystallization of MOR zeolite as an impure phase especially at low reaction temperature, and possess a significant effect on the morphology and the crystal size of TI-IF-FER zeolite.     

系列硅铝比纳米薄层ZSM-5分子筛的合成和表征

以自制不对称双子季铵盐表面活性剂为模板, 在水热合成体系中控制合成系列硅铝比纳米薄层ZSM-5分子筛.采用X射线衍射(XRD)、N₂吸附-脱附、X射线荧光光谱(XRF)、扫描电镜(SEM)和²⁷Al魔角旋转核磁共振(²⁷Al MAS-NMR)对合成的样品进行了表征. 详细研究了晶化温度、晶化时间、结构导向剂(SDA)用量、碱度等对合成的影响和纳米薄层ZSM-5分子筛的形成过程. 结果表明: 分子筛硅铝比越高, 结构导向剂用量越大, 所需的晶化时间越短; 晶化温度越高, 晶化时间越短; 且不同硅铝比纳米薄层ZSM-5分子筛的形貌规整度、比表面积和介孔/微孔孔容比例随着硅铝比而变化.     

Crystallization and Spontaneous Phase Transformation of MTN-Type Zeolite with Tetragonal Symmetry

MTN-type zeolite with tetragonal symmetry was hydrothermally synthesized in a reactant system of Na₂O-SiO₂-NaF-H₂O using N-ethyl-hexamethylenetetraammonium bromide as the template. A spontaneous phase transformation of the as-synthesized zeolite at ambient temperature from tetragonal to cubic symmetry was investigated with polarized light microscopy, X-ray powder diffraction, ²⁹Si magic angle spinning nuclear magnetic resonance, and differential scanning calorimetry. The results of the investigations indicate that the as-synthesized tetragonal MTN zeolite is a metastable phase.     

异相晶种诱导快速合成低硅菱沸石分子筛

在不含有机模板剂体系(OSDAs)中,利用异相晶种(T型分子筛)诱导快速合成出纯相的低硅菱沸石分子筛。采用XRD、SEM、TEM、27Al MAS NMR和紫外拉曼等手段表征分子筛的结构属性和形貌特点。详细研究了菱沸石分子筛的晶化过程以及晶种添加量、nAl2O3/nSi O2、nH2O/nSiO2和碱度对菱沸石分子筛晶化的影响,并探讨T型分子筛晶种诱导合成菱沸石分子筛的晶化机理。原位合成体系中仅形成L型分子筛晶相,而一定量T型分子筛异相晶种的加入诱导溶胶快速制备出纯相的菱沸石分子筛。T型分子筛晶体在一定的水热条件下不断溶解而释放的六元环(6R)和四元环(4R)迅速形成菱沸石分子筛特征笼(CHA笼),抑制了L型分子筛特征单元和特征笼(不含四元环的CAN笼)的形成。     

Hydrothermal conversion of zeolite omega from magadiite with assistance of seed crystals

In this work, we report a rapid and sustainable synthetic strategy of zeolite omega with the addition of omega seeds via the transformation of magadiite with an initial chemical recipe of 0.76 NaOH: SiO₂: 0.01 Al₂O₃: 7–14H₂O, and the crystallization time was shortened to 5 h at 80 °C. The effect of experiment parameters has been discussed in details. In addition, the conversion behavior and the changes of secondary building units were characterized and studied by X-ray diffraction (XRD), scanning electron microscopy, Fourier Transform infrared (FT-IR), and Raman spectroscopy and ²⁷Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy. During the conversion process, omega seeds would be partially destroyed and residual seeds supplied substrate for the growth of zeolite omega, most parts of five-membered rings and six-membered rings in magadiite were remained as building units to promote the formation of zeolite omega, and Al species preferred to enter T2 position which was located in six-membered rings. The toluene adsorption property of final product was also measured.     

One-step synthesis of hierarchical aluminosilicate aggregates using bifunctional alkanolamine as single template

Highly active, hierarchical zeolite ZSM-5 aggregates have been prepared in a one-step synthesis using alkanolamine as single template. The effects of SiO₂/Al₂O₃, pH and H₂O/SiO₂ on the aggregate morphology of the ZSM-5 nanocrystals were investigated. The obtained aggregate zeolites characterized by SEM, TEM and BET possessed significant textual porosity (up to 0.22 cm³/g), which could be tuned by the number of substituents in the alkanolamine molecules and the amount of aluminum in the synthetic mixtures. These zeolite aggregates showed high activities for Friedel–Crafts alkylations and may curtail the filtration difficulties during the synthesis and applications to some extent.     

AlMCM-41介孔分子筛的合成及表征

以拟薄水铝石为铝源、水玻璃为硅源、十六烷基三甲基溴化铵为模板剂,在110℃时水热晶化合成了含Al的MCM-41介孔分子筛.采用X射线衍射(XRD)、N2吸附-脱附、固体29Si、27Al魔角旋转核磁共振技术(MASNMR)、扫描电镜(SEM)及吡啶吸附傅里叶变换红外(FTIR)光谱技术对AlMCM-41分子筛进行了表征.结果表明:AlMCM-41分子筛具有六方排列的孔道结构,同时具有很高的相对结晶度、比表面积和孔容,且孔分布单一;AlMCM-41分子筛中Si原子在骨架内键合的程度更高,使AlMCM-41分子筛具有更好的骨架晶化程度;同时具有四配位骨架铝,使AlMCM-41介孔分子筛具有适当的酸性.     

不同硅铝比的MCM-22分子筛的气相硅烷化处理

对不同硅铝比的MCM-22分子筛进行气相硅烷化处理,并采用X射线衍射、固体核磁、N₂吸附-脱附和甲苯吸附等技术对样品进行了表征. 结果显示,原料硅铝比为50~100的MCM-22分子筛均可以利用气相硅烷化,在不脱除骨架铝的基础上,将Si(OH)₂柱撑结构引入其层间超笼系统,从而使层间距增大,孔体积增加; 将密度泛函理论用于计算硅烷化前后的MCM-22分子筛的N₂吸附等温线,成功得到十元环孔道和超笼体系的比表面积和孔体积,发现气相硅烷化使MCM-22分子筛超笼体系的比表面积和孔体积增大,而十元环孔道减小.另外,气相硅烷化可有效提高不同硅铝比MCM-22分子筛的甲苯平衡吸附量.     

A New Practical Route to ZSM‐5 Nanoparticles and Optimization of Synthetic Parameters through D‐optimal Design of Experiments

A D‐optimal experimental design with three levels of SiO₂/Al₂O₃, template/SiO₂, H₂O/SiO₂, Na₂O/SiO₂ and TPABr/TPAOH ratio parameters has been used to optimize the experimental parameters by an analysis of variances (ANOVA). The effects of these ratios in the initial synthetic mixture on the size of the ZSM‐5 zeolite nanoparticles have been studied. XRD and FE‐SEM analyses were used to characterize synthetic samples. Fischer test results showed that H₂O/SiO₂ and TPABr/TPAOH ratios are the most and least effective parameters, respectively, in the range studied. The most important two‐way interaction variables were the interaction of template/SiO₂ and TPABr/TPAOH molar ratios. The average particle size was in the 34–79 nm range. Furthermore, a mathematical model for the synthesis of ZSM‐5 zeolite nanoparticles was derived using experimental results. The optimized gel composition is as follows: SiO₂/Al₂O₃₌91.20, template/SiO₂₌0.16, H₂O/SiO₂₌40.42, Na₂O/SiO₂₌0.0147 and TPABr/TPAOH=0.