微波固相法快速制备Cu-ZSM-5催化剂

以乙酸铜为原料,ZSM-5沸石分子筛为载体,采用微波固相法制备了Cu-ZSM-5催化剂,通过原子吸收（AAS）测定了不同投料比（mCu（AC）2.H2O：mZSM-5）、微波作用的温度和微波作用的时间对Cu负载量的影响,并通过FT-IR、XRD等方法对Cu-ZSM-5的结构和物性进行了表征,结果表明,微波固相法可将Cu（AC）_2完全分散于ZSM-5分子筛表面,Cu的负载量可高达23.11wt%,分散的Cu（AC）_2与分子筛表面羟基作用形成了新的Cu-O键,这种经过Cu（AC）_2修饰的ZSM-5表面具有更加温和的Lewis酸性。     

Preparation of zeolite-coated cordierite honeycombs prepared by an in situ crystallization method

Zeolite thin films were prepared on cordierite (Mg₂Al₄Si₅O₁₈) honeycomb substrates by in situ crystallization using soft hydrothermal conditions. The synthesized zeolite films (zeolite A and ZSM-5) were characterized by XRD, FTIR, SEM, NH₃-TPD, and Ns₂ and propane gas adsorption. Zeolite-A films were prepared by dip-coating on a cordierite substrate in a precursor of molar composition of Na₂O:Al₂O_3: SiO_2: H₂O = 4:1:2:100 and heating in an autoclave at 80 °C for 6–10 h. The resultant zeolite-A films consisted of cubic crystals about 2–3 μm in size, achieving a thickness of 20 μm after re-coating. ZSM-5 films were similarly formed using a microporous silica precursor obtained by selective leaching of metakaolinite with tetrapropylammonium hydroxide (TPAOH) as the templating agent. The molar composition of the precursor was NaOH:microporous silica:TPAOH:H₂O = 1:10:1:200. The dipped substrate covered with the wet precursor gel was heated in an autoclave at 150 °C for 24 h. The resultant films were composed of short prismatic <1 μm crystals achieving thickness of several to 10 μm after re-coating. The microstructure and porous properties of the ZSM-5 films were found to change according to the chemical composition and surface treatment of the cordierite substrates. The presence of a SiO₂-rich interfacial layer between the substrate and zeolite film increased the amount of zeolite formed and the physical adsorption but decreased the solid acidity and amount of chemisorption.     

Preparation of zeolite-coated cordierite honeycombs prepared by an in situ crystallization method

Zeolite thin films were prepared on cordierite (Mg₂Al₄Si₅O₁₈) honeycomb substrates by in situ crystallization using soft hydrothermal conditions. The synthesized zeolite films (zeolite A and ZSM-5) were characterized by XRD, FTIR, SEM, NH₃-TPD, and Ns₂ and propane gas adsorption. Zeolite-A films were prepared by dip-coating on a cordierite substrate in a precursor of molar composition of Na₂O:Al₂O_3: SiO_2: H₂O=4:1:2:100 and heating in an autoclave at 80 °C for 6–10 h. The resultant zeolite-A films consisted of cubic crystals about 2–3 μm in size, achieving a thickness of 20 μm after re-coating. ZSM-5 films were similarly formed using a microporous silica precursor obtained by selective leaching of metakaolinite with tetrapropylammonium hydroxide (TPAOH) as the templating agent. The molar composition of the precursor was NaOH:microporous silica:TPAOH:H₂O=1:10:1:200. The dipped substrate covered with the wet precursor gel was heated in an autoclave at 150 °C for 24 h. The resultant films were composed of short prismatic <1 μm crystals achieving thickness of several to 10 μm after re-coating. The microstructure and porous properties of the ZSM-5 films were found to change according to the chemical composition and surface treatment of the cordierite substrates. The presence of a SiO₂-rich interfacial layer between the substrate and zeolite film increased the amount of zeolite formed and the physical adsorption but decreased the solid acidity and amount of chemisorption.     

汽相转化法制备无粘结剂小晶粒 ZSM-5沸石

以硅藻土为原料,混合部分硅溶胶与少量晶种导向剂进行成型,然后进行汽相转化,制备了无粘结剂小晶粒ZSM-5沸石.晶种导向剂中的沸石微晶和结构单元诱导硅铝原料转化为交错生长的ZSM-5沸石,导致无粘结剂沸石的生成.产物的表征结果表明,制备的无粘结剂小晶粒ZSM-5成型沸石具有丰富的孔结构,较大的比表面以及较高的机械强度,酸性质可调,可用作催化材料或吸附剂.     

PBAT/ZSM-5分子筛共混薄膜的制备与性能

目的 以聚己二酸-对苯二甲酸丁二酯(PBAT)为基材,制备PBAT/ZSM-5分子筛共混薄膜,研究分子筛含量对薄膜性能的影响.方法 通过共混熔融挤出流延法制得含不同质量分数ZSM-5分子筛(0％,1％,3％,5％,7％)的PBAT薄膜,测定分析不同分子筛质量分数对薄膜的颜色、透明性、结构、气体阻隔性、力学性能等性能的影响.结果 随着分子筛质量分数的增加,透明性和断裂伸长率显著降低,抗拉强度先增加后降低,质量分数为1％分子筛的薄膜抗拉强度相对较大,较纯PBAT薄膜增加了12.34％;薄膜氧气透过性能整体上呈上升趋势,二氧化碳透过性和CO2/O2透过比均逐渐增加,水蒸气透过性显著降低,与纯PBAT薄膜相比,质量分数为7％分子筛PBAT薄膜的氧气和二氧化碳透过系数分别增加了18.48％,33.51％,水蒸气透过系数下降了43.28％,CO2/O2透过比由原来的8.84增加到9.96;薄膜表面和横截断面均变得粗糙,局部区域有团聚现象,且随分子筛含量的增加而变得明显.结论 ZSM-5分子筛的少量加入,可以影响PBAT薄膜力学性能,降低其水蒸气透过性,调节薄膜的气体选择透过性,为其应用于生鲜果蔬包装提供基础.     

Catalytic activity of Co/MCM-41 and Co/SBA-15 materials in toluene oxidation

Cobalt-containing MCM-41 and SBA-15 mesoporous materials were prepared by the pH-adjusting of the impregnation solution. The modified materials were investigated by X-ray diffraction, N₂ physisorption, temperature-programmed reduction, DR UV–Vis diffuse reflectance, and FT-IR spectroscopy of adsorbed pyridine. The pH of the impregnation solution influences the surface charge of the mesoporous support and therefore determines the strength of interaction between the cobalt precursor and the mesoporous support. The formation of different cobalt oxide species in different ratios, depending on the pH of the impregnation solution, was established for both materials. The modified Co/MCM-41 and Co/SBA-15 materials were active in toluene oxidation. Their catalytic activity is predetermined by the nature, the reducibility, and the dispersion of the obtained cobalt oxide species.     

ZSM-5 zeolite modified with vanadyl ions

Properties of the ZSM-5 zeolite modified with VO²⁺ ions in a one-step exchange reaction in water medium have been investigated. Physicochemical characterization (chemical analysis, XRD, MAS n.m.r., e.s.r.) shows that during the preparation the ZSM-5 zeolite structure remains preserved and the vanadyl ions enter the zeolite structure. Sample acidity is of Brönsted and Lewis types and can be reduced by treatment with NaCl solution. Doping with vanadyl ions produces catalysts active in ammoxidation of m-xylene.     

Synthesis of cobalt containing ZSM-5

Cobalt-ZSM-5 is prepared by addition of various cobalt containing substrates to ZSM-5 synthesis gels. The existence and homogeneity of intrazeolitic cobalt is established from XPS and electron microprobe analyses. Variations in the synthesis gel composition were found to influence the amount of intrazeolitic cobalt in the ZSM-5. In at least one preparation, the ion exchange data are consistent with cobalt occupying framework sites. Cobalt-ZSM-5 exposure to 3 atm. H₂ at 470°C and 21 atm. rsol|CO/H₂ (1:1) at temperatures to 470°C did not reduce the cobalt to the zero-valent state and did not cause the cobalt to migrate to the outer surface of the ZSM-5.     

汽相转化法制备纳米晶组成的块状ZSM-5多孔沸石

在ZSM-5沸石前驱体中加入羧甲基纤维素钠并制得干胶, 然后通过蒸汽相转化制得了大块状ZSM-5沸石。由于羧甲基纤维素钠与硅铝物种之间的相互作用干扰了沸石晶体的正常生长, 这种干扰所产生的“键阻断”作用导致合成的大块状ZSM-5沸石由100~150 nm的初级ZSM-5沸石晶体组成, 在这些初级粒子之间存在2~20 nm的二次介孔结构。异丙苯催化裂化结果表明, 由于纳米沸石具有较高的外表面积和较大的介孔孔容, 比参比催化剂表现出更高的异丙苯转化率。     

Silver-embedded zeolite crystals as substrates for surface-enhanced Raman scattering

This paper reports the preparation of a type of Ag-embedded zeolite crystals as surface-enhanced Raman spectroscopy (SERS) substrates by chemical reduction of Ag⁺-exchanged ZSM-5. Ag⁺ ions were loaded into the zeolite framework by ion exchange. Then the exchanged-Ag⁺ ions were reduced and metallic silver clusters formed inside the zeolite channel. The resulting Ag-embedded zeolite crystals are characterized by using a number of techniques including X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy to confirm silver formed inside the crystal channel. The fabricated Ag-embedded ZSM-5 zeolite substrates displayed strong and reproducible SERS activity for different Raman probe molecules such as Tris(2,2′-bipyridyl) ruthenium(II) chloride (RuBpy) and rhodamine 6G (R6G). Since silver embedded into the zeolite channel without changing the crystal surface property, the Ag–ZSM-5 zeolite crystal can be used to prepare different SERS-active substrate (SERS-tags), in which different probe molecules may be detected. Such Ag-embedded zeolite substrate would be useful in chemical and biological sensing and in the development of SERS-based analytical devices.     

酸碱复合处理制备多级孔ZSM-5分子筛及其甲醇制汽油反应性能

以商业ZSM-5分子筛为原料, 分别采用碱处理和酸碱复合处理法制备了多级孔ZSM-5分子筛。利用XRD、FT-IR、SEM、TEM以及氮气吸-脱附等手段对样品进行了表征, 并评价了样品的MTG反应性能。结果表明: 利用单纯碱处理或酸碱复合处理商业ZSM-5分子筛均可制备晶体内富含介孔和大孔的多级孔ZSM-5分子筛。与商业ZSM-5原料相比, 多级孔ZSM-5分子筛催化剂的介孔比表面积、介孔孔容以及酸性位“可接近性指数”等显著增加, 酸量明显减少, 酸强度降低。催化评价结果显示, 多级孔ZSM-5分子筛催化剂在大幅提高汽油产品收率、延长使用寿命的同时降低了芳烃收率。与碱处理样品相比, 酸处理能够进一步调节样品的酸性质和孔结构, 因此酸碱复合处理所得多级孔ZSM-5分子筛催化剂的物化性质和催化性能得以进一步提升。     

乙二醇法制备负载型钴基-堇青石催化剂及其催化燃烧甲苯的活性

用乙二醇法和浸渍法制备两种负载在堇青石上的钴基负载催化剂,并用XRD、XPS、TPR和TPD对制备的催化剂进行表征,比较两种催化剂催化氧化(燃烧)甲苯的活性。研究结果表明,与浸渍法制备的Co/cord催化剂相比,乙二醇法制备的催化剂Co/cord-EG对甲苯催化燃烧活性明显提高。应用乙二醇法制备Co/cord-EG负载型催化剂,Co元素主要以Co2+存在于载体表面;而传统浸渍法制备的Co/cord催化剂,Co元素是以Co2+与Co3+的两种化学状态存在于载体表面。应用乙二醇法制备Co/cord-EG负载型催化剂,有助于在载体表面形成比较均匀的吸附活性位。应用乙二醇法制备的Co/cord-EG催化剂,催化活性组分能在载体表面上以更小颗粒而且更高的分散度存在,从而能明显提高其催化活性。     

一步合成核壳结构ZSM-5/EU-1复合分子筛及其表征

在添加适量柠檬酸的条件下采用双模板剂一步法, 一次晶化合成ZSM-5/EU-1核壳共生复合分子筛, 对其物理化学性质进行表征, 结果显示: 核壳分子筛中存在ZSM-5和EU-1两种分子筛晶相, 且EU-1分子筛在ZSM-5分子筛表面缺陷处外延生长; 复合以后核壳分子筛为微孔-介孔多级孔道结构, 且其微孔孔径达到0.94 nm; 相比于单一分子筛, 核壳分子筛的强酸量相对提高, 酸性质有所改善。通过对柠檬酸加入量、晶化时间影响因素的分析, 得到合成核壳共生结构的最佳条件为: n(citrate)/n(Al₂O₃)=0.8~1.2, 晶化时间为72~96 h, 并推测核壳分子筛可能的生长过程。     

气相转移法制备多孔双相沸石复合物

采用气相转移法制备了同时含有Y和ZSM-5沸石的双相沸石复合物。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、N₂吸附-脱附和骨架红外(FT-IR)等手段对合成的样品进行了表征。结果表明, 合成的样品受Y型沸石的添加量、干胶制备条件和气相转移法转化条件的影响; 水热预处理后的ZSM-5沸石前驱体中具有ZSM-5沸石的骨架特征振动峰, 归结于ZSM-5沸石晶核或微晶的形成, 这有利于在气相转移法转化过程中引导或促使体系向ZSM-5沸石相的转变, 并有利于抑制ZSM-35杂晶的形成; Y型沸石在蒸汽处理过程中的脱铝过程导致合成的沸石复合物具有介孔结构。     

Preparation of metal ion (Fe and Ni) doped TiO2 nanoparticles supported on ZSM-5 zeolite and investigation of its photocatalytic activity

Metal ion doped TiO₂ nanoparticles supported on ZSM-5 zeolite (M-TiO₂/ZSM-5 composites, M = Fe or Ni) were synthesized by hydrothermal method. The prepared composites were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis diffuse reflectance spectra (DRS). The photocatalytic activities of composites were evaluated by degradation of yellow GX aqueous solution under ambient condition. Fe-TiO₂/ZSM-5 composite showed to be more efficient catalyst for degradation of dye molecules as compared with Ni-TiO₂/ZSM-5 and TiO₂/ZSM-5. Its higher photocatalytic activity is attributed to the effective separation of charge carriers that will be discussed in this paper in detail.     

纳米ZSM-5沸石合成方法及应用

ZSM-5沸石由于其特殊的孔道结构以及高的硅铝比，具有优良的稳定性，被广泛用作催化剂。将ZSM-5沸石纳米化后，其应用途径更为宽阔。本文首先介绍了几种常见纳米沸石的合成方法，并在此基础上介绍了ZSM-5沸石的合成和应用。     

A novel method for the growth of ZSM-5 zeolite membrane on the surface of stainless steel

Thin ordered micropore ZSM-5 zeolite membrane has formed on the stainless steel surface. The influence of three different pre-treatment methods for the growth of ZSM-5 zeolite membrane on the stainless steel was studied, including mechanical polishing, soaking in a 20 wt.% sulfuric acid aqueous solution and anodic oxidation treatment. It was found that the anodic oxidation technique was more favorable for the growth of ZSM-5 zeolite membrane on the stainless steel surface compared with the other two methods. By this appropriate pre-treatment process, ordered ZSM-5 zeolite membrane was immobilized on the stainless steel surface and it showed good interaction with the stainless steel. Energy-dispersive X-ray (EDX) spectroscopy result indicates that the ZSM-5 zeolite membrane has a Si/Al ratio of 37. X-ray diffraction (XRD), N₂ adsorption and scanning electron microscopy (SEM) were used to study the crystal structure, specific surface area and morphologies of the ZSM-5 zeolite membrane.     

Facile and selective approach towards synthesis of a series ZSM-5/ZSM-12 catalysts for methanol to hydrocarbons reactions: Applying different synthesis driving force and conditions

The use of ultrasonic waves was developed for synthesis of zeolites at shorter crystallization time with improving their desirable properties. A series of nanostructured ZSM-5/ZSM-12 composite zeolites with different Si/Al ratios and alkalinity using organic templates were prepared by hydrothermal and sonochemical synthesis methods. The physicochemical properties of synthesized nanocatalysts such as structure, morphology, textural, and acidity were characterized via XRD, FESEM, N₂ physisorption, FTIR, TPD-NH₃, TGA-DTG techniques. The results revealed that increasing the Si/Al ratio and alkalinity in the hydrothermal samples enhanced the crystallization, formation of amorphous microcrystals, and dominant phase of MFI with decreasing MTW competitive phase. Zeolites synthesized by high-temperature and short-time sonochemical method had higher crystallinity, less dominant phase of ZSM-5, smaller crystals, greater surface areas, higher concentration of Brønsted acid sites, and stronger strength of moderate/strong acid sites. The catalytic performance of the zeolites for MTH conversion was evaluated under a reaction temperature of 450 °C at different times on stream. The results showed that the sonochemical zeolite had a higher methanol conversion (100%), higher selectivity toward olefins (28% vs. 19%) with more C₃⁼/C₂⁼ ratio (0.79 vs. 0.58), and lower alkanes selectivity (66% vs. 72%) after 240 min TOS.     

A high acid mesoporous USY zeolite prepared by alumination

A high-acidity HUSY zeolite with mesoporous structure was prepared by alumination with a dilute aqueous NaAlO₂ solution and characterized by XRD, N₂ adsorption, IR framework vibration and ²⁹Si MAS NMR methods. The results indicated the extra-framework aluminum was reinserted into the tetrahedral framework through isomorphic substitution of framework Si (0Al) sites by Al ions, whereas the crystal and micropore structure were unaltered. FTIR spectra of hydroxyl vibrations and pyridine adsorbed on realuminated zeolites showed that the number of Brønsted acid sites and strong Lewis acid sites increased whereas weak Lewis acid sites decreased twice. The mesoporous structure composed of inter-and intra-crystalline pores in the aluminated HUSY increased the external surface area of the zeolite, improving accessibility of molecules to the active sites and enhancing its catalytic ability. The realuminated HUSY zeolite supported with Ru catalyst exhibited a higher catalytic activity for benzene hydrogenation than the parent HUSY zeolite; the reaction rate in comparison to the mesozeolite increased by 5.5 times.     

Removal of pyridine from liquid and gas phase by copper forms of natural and synthetic zeolites

Zeoadsorbents on the basis of copper forms of synthetic zeolite ZSM5 and natural zeolite of the clinoptilolite type (CT) have been studied taking into account their environmental application in removing harmful pyridine (py) from liquid and gas phase. Sorption of pyridine by copper forms of zeolites (Cu-ZSM5 and Cu-CT) has been studied by CHN, X-ray photoelectron spectroscopy, X-ray powder diffractometry, FTIR spectroscopy, thermal analysis (TG, DTA and DTG) and analysis of the surface areas and the pore volumes by low-temperature adsorption of nitrogen. The results of thermal analyses of Cu-ZSM5, Cu-(py)(x)ZSM5, Cu-CT and Cu-(py)(x)CT zeolitic products with different composition (x depends on the experimental conditions of sorption of pyridine) clearly confirmed their different thermal properties as well as the sorption of pyridine. In the zeolitic pyridine containing samples the main part of the pyridine release process occurs at considerably higher temperatures than is the boiling point of pyridine, which proves strong bond and irreversibility of py-zeolite interaction. FTIR spectra of Cu-(py)(x)zeolite samples showed well resolved bands of pyridine. The results of thermal analysis and FTIR spectroscopy are in a good agreement with the results of other used methods.