Synthesis of a new molecular sieve using DABCO-based structure-directing agent

A new 1,4-diazabicyclo[2.2.2]octane (DABCO)-based quaternary ammonium compound is designed, synthesized, and used as structure-directing agent (SDA) for molecular sieve synthesis. Several 1,1′-alkylenedi(4-aza-1-azonia-2,5-dimethylbicyclo[2.2.2]octane) type SDAs are used in all-silica synthesis mixtures. Among the SDAs tested, the use of 1,1′-butylenedi(4-aza-1-azonia-2,5-dimethylbicyclo[2.2.2]octane) gives a new phase (GUS-1), whereas the use of other SDAs gives zeolite beta (^*BEA), ZSM-12 (MTW), and ZSM-5 (MFI). The GUS-1 is indexed in the orthorhombic crystal class with refined lattice constants a=16.4206(4) Å, b=20.0540(4) Å and c=5.0464(1) Å. The crystalline architecture of GUS-1 shows the same [0 0 1] projection of the framework as that of mordenite (MOR), and is characterized by a one-dimensional 12-membered ring channel system that is closely related to the channels of ZSM-12. The GUS-1 is stable to heat upon calcination at 700 °C in air. The calcined material exhibits adsorption capacity that is comparable to typical large-pore one-dimensional microporous silicates. The behavior of the SDA during synthesis is also discussed.     

Synthesis and characterization of mesoporous molecular sieve nanoparticles

Mesoporous molecular sieve was prepared hydrothermally by a two-step method with materials of cetyltrimethyl ammonium bromide (CTAB), as a template, and sodium metaaluminate (NaAlO₂) and sodium silicate (Na₂SiO₃·9H₂O), as aluminum and silicon sources, respectively. The mesoporous molecular sieves are well ordered and have high thermal and hydrothermal stabilities. The as-prepared samples were characterized by powder X-ray diffraction (XRD), atomic force microscopy (AFM), transmission electron microscopy (TEM), thermogravimetry-differential scanning calorimetry (TG/DSC), Fourier transform infrared spectroscopy (FT-IR) and nitrogen adsorption experiments. Particle size distribution was in the 30–50 nm range, BET surface area was more than 800 m²/g, thermal stability was higher than 1023 K, the mesoporous structure was not entirely damaged at a calcination temperature of 1123 K and there was no clear change in ordering degree, pore size, and surface area of the mesoporous molecular sieve after hydrothermal treatment at 373 K for 10 days. The activity and selectivity of benzene hydrogenation to cyclohexane by mesoporous molecular sieve-supported Pt was up to 100%. The catalytic activity didn’t decline in a reaction period of 30 h.     

亚微米4A分子筛的合成与表征

以云南云天化国际股份有限公司的磷肥副产物硅胶湿样为基础原料,补加铝酸钙,水热法制备亚微米4A分子筛.采用XRD、SEM和FT-IR等分析手段对产品进行了表征.结果表明采用水热法制备的产品结晶度为95%,形状规则、大小均匀,分布范围较窄;粒度较小、粒度≤1μm的可达到100%;钙离子交换容量为336 mgCaCO3/g(干基)4A分子筛,白度为95%,完全满足洗涤助剂的要求.     

NaY分子筛合成工艺

报道了以具有独特组成的硅铝凝胶为导向剂制备NaY分子筛的方法。所合成的NaY分子筛用SEM、XRD和BET等进行了表征,结果表明,该NaY分子筛粒径2μm左右,硅铝比n(SiO2)/n(Al2O3)为3.28,结晶度90%,比表面积703 m2/g。除晶化过程外,该合成NaY分子筛的工艺过程均在室温下进行,具有反应条件温和,易于调控的特点。     

Synthesis of aluminophosphate molecular sieve AlPO4-11 nanocrystals

AlPO₄-11 nanocrystals, 0.05×0.08 μm in size, were synthesized by optimizing the following chemical parameters: the crystallization temperature and time, the H₂O content, the molar ratio of phosphorus to organic template (P₂O₅/R), and the HF content. The products were characterized by powder X-ray diffraction and scanning electron microscope. AlPO₄-11 nanocrystals could not be obtained by optimizing only the crystallization temperature, time and the water content, but obtained by optimizing the molar ratio of P₂O₅/R, the organic template, and the HF content.     

碳分子筛变压吸附空气分离活性及表征

石油焦基活性炭经Ni(NO3)2溶液室温浸渍过夜,红外灯缓慢烘干(Ni载持量5%),再经1-丁烯沉积处理,制备了催化炭沉积碳分子筛S-CMS,探讨了空气进料流量、压力和再生时间对碳分子筛空分效果的影响。结果表明,当流量为10~50 mL/min时,对空气分离效果影响很小;当吸附压力增加时,氮气浓度应该是增加的。脱附时间大于60 s时,S-CMS能够被再生。与商用T1-CMS比较,S-CMS是优秀的,在常温常压下,可获得浓度为93%的富氮气体。通过对碳分子筛表面结构的FT-IR、骨架结构-XRD及其氧化性in-situ TG/DTA的测试显示,S-CMS具有微孔分布独特的骨架网络结构,是一种潜在的优越变压吸附剂。     

PO_4~(3-)/Si-MCM-41介孔分子筛合成与表征

采用十六烷基三甲基溴化铵作为模板剂,正硅酸乙酯为硅源,用水热晶化法在乙二胺为碱性介质中合成了Si-MCM-41介孔分子筛,并用磷酸浸渍法制备PO3-4/Si-MCM-41。通过氮气吸附-脱附、红外光谱、Hammett指示剂胺滴定等方法对所合成样品进行了表征。结果表明,合成的分子筛具有典型的介孔结构特征,孔径分布较窄,具有较大的比表面积和较强的酸性。     

A new composite of crystalline silicotitanate for sequestration of 137Cs and 90Sr from low-level aqueous waste solution

ABSTRACT

A new composite of crystalline silicotitanate (CST) has been synthesized for the sequestration of Cs and Sr from low-level liquid waste generated in the nuclear industry. The product characterization using X-RAY DEFRACTION (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirmed the presence of CST crystals in the composite. Sorption studies carried out under various test conditions showed that the composite has high affinity for both Cs and Sr. Results of structural characterization of Cs and Sr-loaded CST indicated that the overall structural integrity remained intact after substitution of Na⁺ by Cs⁺ or Sr²⁺. The exceedingly good Cs and Sr sorption performance displayed by the CST composite will find applications in the treatment of nuclear waste.     

Novel carbon molecular sieve honeycomb membrane module: configuration and membrane characterization

A new production concept of carbon molecular sieve membranes modules is described. The supported membrane synthesis process allows for industrial production with uniform and reproducible properties, using flat membranes as a starting precursor. The corresponding membrane modules are made in a honeycomb configuration, leading to high packing density and thermochemical stability. Some of the carbon membranes produced for use in these modules are characterized. Species H₂, O₂, N₂, CO₂ and SF₆ were used in monocomponent adsorption and permeation experiments to obtain adsorption equilibrium and permeation data. High permeabilities were attained in combination with high selectivities. The pore size distribution of the membrane was determined. A number of complementary morphological and structural characterizations were also performed.     

表面富钛复合钛硅分子筛的合成与表征

以全硅分子筛silicalite-1为硅源,利用水热晶化法合成表面富钛的钛硅分子筛CTS,采用XRD、N2吸附-脱附、IR、XRF、UV—vis、XPS、DTA—TGA和SEM等对合成的分子筛进行表征。结果表明,合成的钛硅分子筛CTS具有MFI拓扑结构,钛物种主要集中在其表面,催化性能评价表明,在苯酚羟基化探针反应中合成的钛硅分子筛CTS具有较好的活性和苯二酚选择性,重复使用次数优于常规利用硅酯为硅源合成的分子筛TS-1。     

MCM-48中孔分子筛的合成

在文献报道的水热法合成MCM 48中孔分子筛的基础上,针对在不同时期合成MCM 48合成重复性不好的问题,系统地考察了滴加正硅酸乙酯(TEOS)时溶液的温度,发现在溶液温度为20℃时滴加TEOS时配制的合成液能合成出有序性较高的MCM 48,并考察了焙烧温度及气氛对合成MCM 48中孔分子筛的影响,通过XRD、TG/DSC等对合成的产物进行了表征。     

SAPO-11分子筛的水热合成及其金属负载改性的研究进展

简述了SAPO-11分子筛的结构和合成原理,介绍了传统水热合成方法。通过几种方法对其进行改进,比较了改进前后分子筛的结构和性能。同时归纳和总结了金属负载改性对SAPO-11分子筛应用于烷烃异构化性能的影响。     

WSiOx介孔分子筛的合成与表征

以阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)作为模板剂,正硅酸乙酯(TEOS)作为硅源,在强碱性条件下,加入过渡金属氧化物偏钨酸铵合成得到WSiOx介孔分子筛,使用乙酰丙酮作为助剂,考察其对孔结构的影响,通过X射线衍射仪(XRD)、N2吸附-脱附、原位红外(FT-IR)、扫描电镜(SEM)表征手段对合成出的WSiOx上分子筛的结构性能进行研究.随着W质量分数的增加,介孔特征衍射峰的有序度增加,质量分数大于6%后有序度下降;W的加入没有破坏介孔分子筛的骨架结构.最后的结果得到,最佳W质量分数为5%,模板剂质量分数为1.8%,乙酰丙酮质量分数为9%.平均孔径为4.68 nm,比表面积为966 m2/g.     

对甲苯磺酸改性SBA-15的合成及催化合成乙酸正丁酯

采用浸渍法将含有磺酸基的对甲苯磺酸负载在SBA-15表面上,合成含有一定酸性的固体酸催化剂TsOH-SBA-15。催化剂的制备条件为:对甲苯磺酸的浸渍浓度为0.5 mol/L,焙烧温度为300℃,焙烧时间为4 h。用XRD,IR,DTA/TGA,氮吸附-脱附等方法对改性后的样品进行表征。结果表明,改性后的SBA-15分子筛的结构未发生变化,仍具有有序孔道结构。TsOH-SBA-15催化剂对冰乙酸和正丁醇的酯化反应具有较高的活性,正交实验结果为:反应时间80 m in,n(冰乙酸)∶n(正丁醇)=1∶1.2,催化剂用量为冰乙酸质量的5%,此时酯化率可达到95%。     

MCM-41介孔分子筛的合成、改性及应用研究进展

介绍了MCM-41介孔分子筛的优点,主要表现在具有较大的比表面积,孔体积与孔径和可调变等。综述了MCM-41介孔分子筛的合成方法与改性研究现状,阐述了MCM-41介孔分子筛的应用研究进展。     

介孔分子筛SiW12/SBA-15催化合成柠檬酸三丁酯

:将硅钨酸负载在纯硅介孔分子筛SBA-15的表面上,XRD结果表明负载型催化剂SiW12/SBA-15具有纯硅SBA-15的介孔结构.将该催化剂用于合成柠檬酸三丁酯的酯化反应.采用正交实验考察了反应温度、催化剂用量、酸醇摩尔比对柠檬酸转化率的影响,得出最佳反应条件为:反应温度120℃、催化剂用量为总物料质量的1.5%、酸醇摩尔比1:4.在此条件下反应4 h,柠檬酸转化率可达到91.5%,产物的纯度为99.3%.     

钛硅分子筛ETS-10的合成和表征

以硅酸钠溶胶、硫酸钛为起始原料,在含KF碱性水热体系中制备出ETS-10钛硅酸盐分子筛;考察了原料的配比、晶化时间与温度对ETS-10合成的影响。应用XRD、SEM、EDX、FTIR和N2吸附技术表征了合成的ETS-10的结构和物性。结果表明,用组成为n(SiO2)∶n(TiO2)∶n(Na2O)∶n(KF)∶n(H2O)=7.5∶1.0∶5.0∶3.0∶198的凝胶,在463K(48h)和无模板剂的条件下,合成出结晶度良好的ETS-10。ETS-10晶体具有规则的四方切角锥形晶貌和微孔性质,比表面积和孔容分别为383.75cm2/g和0.16cm3/g;典型样品的化学组成接近已知的ETS-10组成表达式(Na,K)2TiSi5O13.4H2O。     

Sn-ZSM-12, a new,large pore MTW type tin-silicate molecular sieve: synthesis,characterization and catalytic properties in oxidation reactions

A new large pore tin-silicate analogue of zeolite ZSM-12 (MTW topology) with Si/Sn molar ratio >70 has been synthesized hydrothermally using a new template, hexamethylene bis(benzyl dimethyl ammonium hydroxide). This material exhibits an expansion in unit cell volume (XRD), an IR band at 970 cm^–1 and a charge transfer band at 205 nm in the UV-Vis region indicating the presence of Si-O-Sn units with Sn⁴⁺ centers in T_d configuration. Sn-ZSM-12 catalyzes the oxidation of phenol,m-cresol andm-xylene using dilute H₂O₂ as an oxidizing agent.     

Microwave preparation of a titanium-substituted mesoporous molecular sieve

A titanium-containing redox material with disordered wormhole-like mesoporous structure was prepared using microwave heating. Substantially accelerated crystallization was achieved using microwave heating compared with the conventional oven heating. Development of the mesopore structure was confirmed by XRD, TEM, and N₂ physisorption. Incorporation of titanium into the mesopore structure was confirmed by UV-vis spectroscopy. A laser light particle size analyzer showed that smaller particle size and narrower particle size distribution were obtained with microwave heating than with oven-heated hydrothermal synthesis. These mesoporous titanosilicates were equally active as catalysts for liquid-phase oxidation of 2,6-di-tert-butylphenol with hydrogen peroxide as an oxidant. This revised version was published online in July 2006 with corrections to the Cover Date.     

轻石脑油中C_6烷烃在5A分子筛上的吸附/脱附等温线研究

测定了轻石脑油中正、异构C6烷烃在5A-1分子筛上的低温(25～80℃)及高温(150～300℃)吸附/脱附等温线,分析了吸附温度、吸附压力、脱附压力对5A-1分子筛吸附/脱附性能的影响。结果表明:正己烷在5A-1分子筛上低温(25～80℃)及高温(150～300℃)下的吸附等温线均为I型吸附等温线,且随着吸附温度的升高,等温线优惠程度逐渐降低。吸附温度25℃、平衡压力7.5kPa时,异构C6烷烃在5A-1分子筛上的吸附量较小,对正己烷平衡吸附量影响不大。对于轻石脑油中的C_6烷烃来说,较适宜的吸附温度优选200～250℃,在该温度范围内,正己烷平衡吸附量为5.68～9.03g/(100g);脱附压力为1.4 kPa时,正己烷脱附量为0.69～2.35g/(100g),能够满足变压吸附的操作要求。