Forming and Gathering of SnO2 Nanoparticles on External Surface of High Silica TON, MFI and FAU Type Zeolites

Tin dioxide （SnO2） nano-particles were prepared on high silica TON, MFI and FAU type zeolites by impregnation of SnC12 solution and subsequent calcination at 873 K. XRD and SAED were used to characterize the crystalline phase, and TEM was used to characterize the morphology, the particle size and the agglomerative state of the formed nano-materials. The nano-particles, which possess 8 nm, 10-80 nm and 6 nm in size, were found to form on the outer surface of TON, MFI and FAU zeolites, respectively. SnO2 microcapsules and SnOz netlike nanostructure were obtained by decomposition of SnO2-TON and SnO2-MFI in 40% hydrofluoric acid at room temperature. Compared with the nano-particles formed on NaY zeolite, the special morphology and the agglomerative state of SnO2 nanostructures on TON and MFI type zeolites with one and two dimension channel system indicate that the heterogeneous framework, surface structure and property perform important function for forming and growing SnO2 nanostructure on the outer surface of the zeolites.     

偏高岭土水热合成NaY分子筛的机理研究

采用茂名高岭土水热合成NaY分子筛,用IR,XRD,NMR,SEM,HRTEM等分析了其晶化过程。结果表明：偏高岭土水热合成Y型分子筛是固相转变机理,晶化过程是一个扩散-成胶-原位重排的过程。     

Experimental Evidence of CO2 Photoreduction Activity of SnO2 Nanoparticles

Tin dioxide (SnO₂) has intrinsic characteristics that do not favor its photocatalytic activity. However, we evidenced that surface modification can positively influence its performance for CO₂ photoreduction in the gas phase. The hydroxylation of the SnO₂ surface played a role in the CO₂ affinity decreasing its reduction potential. The results showed that a certain selectivity for methane (CH₄), carbon monoxide (CO), and ethylene (C₂H₄) is related to different SnO₂ hydrothermal annealing. The best performance was seen for SnO₂ annealed at 150 °C, with a production of 20.4 μmol g⁻¹ for CH₄ and 16.45 μmol g⁻¹ for CO, while for SnO₂ at 200 °C the system produced more C₂H₄, probably due to a decrease of surface −OH groups.     

线团式纳米NaY分子筛复合材料的制备及形成机理

通过在偏高岭土水热合成NaY分子筛的晶化过程中加入乙醇的方法,制备了线团式纳米NaY分子筛复合材料,用XRD、SEM、ICP OES研究了晶化过程中固液相结构和组成的变化,初步探讨了其形成机理,提出了制备纳米NaY分子筛复合材料的条件.     

CuCl2/NaY体系表面分散态研究

铜负载分子筛作为催化剂或吸附剂，在石油化工、环境保护等方面有许多用途[1，2]．已有研究发现，铜交换的Y型分子筛对NO分解等反应具有较高活性及稳定性［3-5］．因此研究铜负载Y型分子筛对有关吸附剂和催化剂的制备有重要意义．我们实验室在研究活性组分在载体表面分散现象时     

The Adsorption of CHClF2 on NaY5.6 Zeolite

The adsorption of CHClF₂ on NaY5.6 zeolite has been studied by measuring the H and F NMR of the adsorbed CHClF₂, focusing in particular on the measurements of the chemical shift and longitudinal relaxation time, as well as the adsorption isotherm measurements. It is possible to determine the coordination structure of the CHClF₂ adsorbed on NaY5.6 zeolite by measuring the adsorption amount dependence of the chemical shift. In addition, the motional activity of the adsorbed molecules in the super cage of the zeolite is discussed on the basis of observed longitudinal relaxation times for various adsorption amounts.     

纳米氧化锡修饰的微催化燃烧式氢气传感器的研制

研制了一种基于多孔纳米氧化锡(SnO₂)催化剂的微催化燃烧式气体传感芯片(Pellistor). 基于微机电系统(Micro- Electro-Mechanical Systems, MEMS)工艺制备硅基封闭膜式微催化燃烧式传感器, 通过气相沉积技术在Pt微加热电极和高温绝缘层表面制备三维纳米氧化锡催化膜, 利用催化膜对氢气良好的催化特性, 采用惠斯通电桥电路进行测量, 实现对空气环境中氢气在0～4%浓度范围内的快速检测, 响应时间和恢复时间分别达到0.65 s和2.32 s, 灵敏度达75.4 mV/1% H₂, 线性度为99.4%. 考察200 天内该传感芯片对氢气的检测能力, 传感芯片表现出良好的稳定性, 精确度保持在95%以上. 在绝缘层高温性能稳定的条件下, 将三维纳米氧化锡应用于微催化燃烧式传感器的氢气检测, 对催化燃烧式传感器性能的改进具有重要的意义.     

高温合成NaY沸石

提出了应用NaY沸石导向剂提供全部硅源合成NaY沸石的新方法, 研究了高温条件下合成NaY沸石的规律和特点, 发现在高温条件下合成NaY沸石不仅晶化速度快, 而且可以在不加有机物的条件下合成较高硅铝比[n(SiO2)/n(Al2O3)=6]的NaY沸石.     

超细NaY分子筛的深度脱铝

通过优化和组合不同脱铝补硅方法,依次经氟硅酸铵处理、600oC水热处理、硅溶胶+草酸处理和800oC水热处理过程,成功实现了200nm超细NaY分子筛的深度脱铝,最终产品骨架硅铝比高达27.3,比表面积为581.9m2/g,分子筛结晶度保持在65%以上.结果表明,对于超细NaY分子筛脱铝,第一步采用氟硅酸铵进行部分缺陷修补尤为重要.根据分子筛晶粒尺寸不同,需严格控制氟硅酸铵用量和处理次数.当晶粒为200nm时,氟硅酸铵与分子筛骨架铝的摩尔比为0.16,处理一次较为适宜.在连续脱铝过程中及时补修脱铝产生的缺陷是保障超细NaY分子筛成功脱铝的关键,而采用氟硅酸铵、硅溶胶、800oC高温水热处理,可有效实施这种骨架修正作用.     

高比表面积蠕虫状介孔SnO2的合成与表征

 以聚乙二醇 (PEG) 为模板剂, 氯化锡为锡源, 尿素为沉淀剂, 采用水热法合成出高比表面积的蠕虫状介孔四方相金红石型 SnO2. 考察了 PEG 分子量及其浓度、水热温度和焙烧温度对 SnO2 孔结构和形貌的影响. 采用 X 射线衍射、N2 吸附-脱附、透射电镜、红外光谱和紫外-可见光谱等技术对样品进行了表征. 结果表明, 模板剂可被水洗除去, PEG 分子量对介孔 SnO2 的比表面积影响不大, 而 PEG 浓度、水热温度和焙烧温度的影响较大. 在以分子量为 6000 的 PEG 与 Sn 的摩尔比为 0.01 的条件下, 于 120 oC 水热处理 29 h 后可合成出比表面积高达 161 m2/g 和平均孔径为 2.6 nm 的蠕虫状介孔 SnO2. 所制得样品具有较好的紫外光吸收性能, 适宜用作催化剂、载体和气体传感器等.     

NaY沸石草酸脱铝

ＮａＹ沸石用草酸溶液脱Ａｌ，随草酸用量增加，脱Ａｌ度增加，结晶度下降，但脱Ａｌ２０％仍能保持９５％以上的高结晶度，实验结果表明，脱Ａｌ量和Ｈ用量呈线性关系，斜率近似０．２５，Ｃ２Ｏ＾２－４有促进脱Ａｌ的作用，脱Ａｌ过程中沸石结晶度的保持３于脱Ａｌ体系的缓冲作用，由草酸的电了平衡和络合平衡构成的脱Ａｌ体系档提供最佳脱Ａｌ条件，脱Ａｌ的沸石产物带有羟基“窝”八面沸石骨架，加热３００℃以上可使羟基“窝”     

Mechanism of Dealumination of NaY Zeolite with Oxalic Acid

RemovalofalundnumfromNaYzeolitewithacidisanimportantprocessinthemodificationofzeolite.ItisdifficulttoremovealundnumfromNaYzeolitedirectlywithacidwhilekeepinghighcrystallinity.Intheworkreportedhere,alundnumisremoveddirectlyfromNaYwithoxalicacidandthemodifiedzeolitekeepshighcrystallinity.Reactionconditions:CSBlreflux,acidaddedin3ondn,allowedtoreactfor3OAnn.CSB2reflux,acidaddedrapidly,allowedtoreactfor3Owhn.CS2525-C,acidaddedraPidly,allowedtoreactfor3Omin.CSA25"C,acidaddedin3omin,a1lowe…     

Densely Packed,Ultra Small SnO Nanoparticles for Enhanced Activity and Selectivity in Electrochemical CO2 Reduction

Controlling the selectivity in electrochemical CO₂ reduction is an unsolved challenge. While tin (Sn) has emerged as a promising non‐precious catalyst for CO₂ electroreduction, most Sn‐based catalysts produce formate as the major product, which is less desirable than CO in terms of separation and further use. Tin monoxide (SnO) nanoparticles supported on carbon black were synthesized and assembled and their application in CO₂ reduction was studied. Remarkably high selectivity and partial current densities for CO formation were obtained using these SnO nanoparticles compared to other Sn catalysts. The high activity is attributed to the ultra‐small size of the nanoparticles (2.6 nm), while the high selectivity is attributed to a local pH effect arising from the dense packing of nanoparticles in the conductive carbon black matrix.     

Effect of antimony dopants on the sorption properties of SnO2

The effects of antimony modifying additive (0.15—0.50 at.% Sb) on the electrophysical and sorption properties of SnO₂ powders with a well developed specific surface were studied in the temperature range of 25—250 °C. Small amounts of antimony (0.15 at.%) increase the conductivity of SnO₂ containing SO₂ and CO chemisorbed in the temperature range of 25—100 °C. This makes this composition promising as a sensitive element of gas sensors.     

In Situ Synthesis of NaY Zeolite with Coal—Based Kaolin

NaY zeolites were in-situ synthesized form coal-based kaolin via the hydrothermal method. The effects of various factors on the structure of the samples were extensively investigated.The samples were characterized by N2 adsorption,XRD,IR and DTG-DTA methods,and the results show that the crystallization temperature and amount of added water play an important role in the formation of the zeolite structure.The 4A and P zeolites are the competitive Phaes present in the resulting product.However,NaY zeolites wiht a higher relative crystallinity,excluding impure crystals and the well hydrothermal stapore size distribution,and this means that optimization of this process might result in a commercial route to synthesize NaY zeolites form coal-based kaolin.     

电化学合成系列锡配合物及纳米SnO2的制备

采用锡金属为"牺牲"阳极,首次在无隔膜电解槽中,电化学一步法制备了纳米SnO₂前驱体锡配合物Sn(OEt)₄, Sn(OBu)₄, Sn(OCH₂CH₂OCH₃)₄, Sn(OEt)₂(acac)₂, Sn(OBu)₂(acac)₂, Sn(OCH₂CH₂OCH₃)₂(acac)₂[acac为乙酰丙酮基],产物通过红外光谱(FT-IR)、拉曼光谱和核磁共振进行表征.同时采用含Sn(OR)₂(acac)₂>的电解液直接水解制备纳米SnO₂粉体,纳米SnO₂通过X射线粉末衍射(XRD)和透射电子显微镜(TEM)进行表征.实验表明,电解时防止阳极钝化,控制温度在40～60℃之间,采用有机胺溴化物为导电盐,可以提高电合成效率;电解合成Sn(OCH2CH₂OCH₃)₄, Sn(OEt)₂(acac)₂, Sn(OBu)₂(acac)₂, Sn(OCH₂CH₂OCH₃)₂(acac)₂的电流效率比Sn(OEt)₄, Sn(OBu)₄高,适宜作为溶胶-凝胶(Sol-gel)法制备纳米SnO₂的原料,制备得到的纳米SnO₂经600℃煅烧后呈球形单分散结构,晶型为四方锡石型,平均粒径在(10±0.4) nm左右.     

Fe2O3改性NaY沸石上吡咯烷亚硝胺的降解

 采用程序升温表面反应（TPSR），NH3－TPD，TG－MS和脉冲催化反应等手段研究了吡咯烷亚硝胺（NPYR）在Fe2O3改性NaY沸石上的催化降解．结果表明，用微波辐射、浸渍或焙烧等不同方法制备的改性沸石对NPYR降解的催化性能各不相同，以浸渍法制备的样品活性最高，但该样品对降解产物NO2的吸附作用较弱．在NPYR的降解反应中，Fe2O3改性NaY沸石上的Fe向沸石外表面迁移和富集，覆盖了沸石表面的铝，使催化剂表现出Fe2O3的性质．     

柠檬酸溶液中NaY分子筛的脱铝行为

硅铝分子筛有机酸配合脱铝是提高其稳定性、引入介孔的一种重要方法.采用X射线衍射、N₂物理吸附、高分辨透射电镜、傅里叶变换红外光谱、²⁷Al和²⁹Si固体魔角自旋核磁共振光谱等方法研究了NaY分子筛柠檬酸脱铝行为.结果表明,柠檬酸浓度对NaY分子筛骨架Al原子的脱出影响尤为显著.反应起始阶段,分子筛骨架铝原子快速脱出,其晶体结构遭到严重破坏.随着反应的进行,分子筛硅铝比和结晶度皆有所增加,表明其骨架结构可能进行了重新排列.75℃下,0.10 mol/L柠檬酸处理2 h的脱铝分子筛样品,与NaY分子筛样品相比,其骨架硅铝比增加了0.6、外表面增加了17 m²·g^-1,脱铝同时产生了大量无定形硅.     

亚硝胺在沸石催化剂上的程序升温表面反应

 采用程序升温表面反应技术研究了二甲基亚硝胺,吡咯烷亚硝胺和环六亚甲基亚硝胺在NaY,NaZSM－5和HZSM－5等沸石及MCM－41中孔分子筛上的脱附及分解．结果表明,沸石对亚硝胺有独特的吸附和催化分解作用．同时,研究了沸石孔结构及表面酸性对亚硝胺分解反应的影响．     

Characteristics of Sol-Gel SnO2 Films Treated by Ammonia

Tin dioxide thin films prepared by sol-gel dip-coating method with ammonia treatment have been studied. By using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy, detailed investigation on the structure and morphology of the films has shown the condensation of Sn-OH and the strengthening of gel network net through ammonia treatment, which leads to the improvement of the adhesion of the films. From the spectral transmission, angular distribution of reflectance and absorption spectrum, the optical properties of the ammonia treated films indicate that the ammonia treated films have a favorable optical performance, and the films are more suitable for acting as antireflective films than the heat-treated films. The ammonia treated films also exhibit higher conductivity compared with the non-treated films.