Preparation of a silica gel–carbon black composite by the sol–gel process in the presence of polymer-grafted carbon black

This paper is concerned with the preparation of a silica gel–carbon black composite by the sol–gel process, which consists of tetraethoxysilane and polymer-grafted carbon black. Polymer-grafted carbon black was synthesized by three methods: (1) cationic polymerization of N-vinyl-2-pyrrolidone, (2) cationic ring-opening polymerization of 2-methyl-2-oxazoline, and (3) radical polymerization of glycidyl methacrylate followed by reaction of glycidyl groups in the grafted polymer chains with 3-aminopropyltriethoxysilane. The polycondensation of tetraethoxysilane proceeded under acidic conditions in the presence of polymer-grafted carbon black to give a deep black silica gel–carbon black composite. The more the content of untreated carbon black was increased, the more the gelation time was shortened. On the contrary, gelation was retarded by grafted polymer chains on the carbon black surface in the case of polymer-grafted carbon black. The scratch hardness of the resulting silica gel–carbon black composite was almost equal regardless of the carbon black content in the presence of untreated carbon black, whereas it was liable to decrease as the content of polymer-grafted carbon black increased. The solvent adsorption properties of the silica gel–polymer-grafted carbon black composite varied with the solubility of grafted polymer chains on the carbon black surface towards the immersion solvent. © 1998 Chapman & Hall     

新型催化材料——介孔氧化铝分子筛的合成、表征以及应用前景

与传统的γ-Al2O3相比,介孔氧化铝分子筛具有较大的比表面积和较窄的孔径分布,作为工业催化剂或催化剂载体,具有更为广阔的应用前景.本文重点介绍了介孔氧化铝分子筛的不同合成方法、结构表征方法和催化性能,分析了模板剂类型、凝胶pH值、洗涤方法、焙烧方式等制备条件对其结构的影响.并对其催化应用进行了评述和展望.     

Metal-oxide-doped silica nanoparticles for the catalytic glycolysis of polyethylene terephthalate

Polyethylene terephthalate (PET) was depolymerized to monomer bis(2-hydroxyethyl) terephthalate (BHET) using excess ethylene glycol (EG) in the presence of metal oxides that were impregnated on different forms of silica support [silica nanoparticles (SNPs) or silica microparticles (SMPs)] as glycolysis catalysts. The reactions were carried out at 300 degrees C and 1.1 MPa at an EG-to-PET molar ratio of 11:1 and a catalyst-to-PET-weight ratio of 1.0% for 40-80 min. Among the four prepared catalysts (Mn3O4/SNPs, ZnO/SNPs, Mn3O4/SMPs, and ZnO/SMPs), the Mn3O4/SNPs nanocomposite had the highest monomer yield (> 90%). This high yield may be explained by the high surface area, amorphous and porous structure, and existence of numerous active sites on the nanocomposite catalyst. The BHET yield increased with time and reached the highest level where equilibrium was established between BHET and its dimer. The catalysts were characterized by their SEM, TEM, and BET surface areas, and via XRD, whereas the monomer BHET was characterized by HPLC and FT-IR. The glycolysis with the Mn3O4/SNPs nanocomposite as the glycolysis catalyst produced a maximum BHET in a short reaction time.     

二氧化碳穿透分子筛床层故障分析和处理

针对60000m3/h空分设备分子筛吸附器出口空气中二氧化碳含量超标的现象,详细分析故障原因,阐述处理措施、效果以及从中得到的经验和教训。     

Photocatalytic properties of the SBA-15 mesoporous silica molecular sieve modified with titanium

We describe three methods of post-synthesis modification of the SBA-15 mesoporous molecular sieve with titanium: impregnation with Ti(OEt)₄ in an ethanolic solution, grafting with titanocene dichloride, and modification with colloidal titania. The products were characterized using X-ray diffraction (XRD) and N₂ adsorption as well as Fourier-transform infrared and ²⁹Si NMR spectroscopies. All three methods yield materials containing 1.4--4.7 wt.% titanium and with high surface areas. The absorbance at 960 cm⁻¹ in SBA-15 modified with colloidal titania and SBA-15 grafted with titanocene indicates the formation of Ti–O bonds. All products showed significant activity towards the degradation of p-chlorophenol. UV-vis absorption spectra of SBA-15 samples modified with titanium indicate that the variation in the photocatalytic activity is governed by isolated titanium sites.     

A sustainable route for the preparation of activated carbon and silica from rice husk ash

An environmentally friendly and economically effective process to produce silica and activated carbon form rice husk ask simultaneously has been developed in this study. An extraction yield of silica of 72-98% was obtained and the particle size was 40-50 nm. The microstructures of the as-obtained silica powders were characterized by X-ray diffraction (XRD) and infrared spectra (IR). The surface area, iodine number and capacitance value of activated carbon could achieve 570 m(2)/g, 1708 mg/g, 180 F/g, respectively. In the whole synthetic procedure, the wastewater and the carbon dioxide were collected and reutilized. The recovery rate of sodium carbonate was achieved 92.25%. The process is inexpensive, sustainable, environmentally friendly and suitable for large-scale production.     

炭分子筛膜的制备及应用研究进展

炭分子筛膜(CMSM)是用于气体分离的一种高效节能新型材料,在气体分离中具有极大的工业化应用潜力.综述了炭分子筛膜的前躯体选择、制备工艺及气体分离应用方面的研究进展,并对炭分子筛膜的发展方向进行了展望.     

Adsorption and diffusion of nitrogen,oxygen, argon,and methane in molecular sieve carbon at elevated pressures

Diffusion and equilibrium adsorption of nitrogen, oxygen, argon, and methane on molecular sieve carbons 3A and 5A were studied at 273, 303, and 323°K. The adsorbate pressure was varied over a pressure range of 0–1.3 MPa in a gravimetric setup. On a molar basis, methane had the highest adsorption capacity among the four gases studied. Oxygen and nitrogen had approximately similar equilibrium adsorption capacity. Equilibrium adsorption data were represented by the Langmuir model and the vacancy solution model (VSM). Langmuir equation showed deviations at high pressures. The isosteric heat of adsorption was found to increase slightly with an increase in surface coverage. Kinetic data showed that oxygen had the highest diffusion rate and methane the lowest. Diffusivities were found to be generally independent of pressure.     

HZSM-5分子筛负载SrTiO_3光催化降解活性艳红X-3B

采用溶胶-凝胶法制备HZSM-5分子筛负载SrTiO_3,对其进行XRD、FTIR和N2吸附-脱附表征,研究负载对活性艳红X-3B光催化降解过程的影响。通过分析降解液的FTIR谱图、紫外-可见光谱和总有机碳(TOC)数据,对活性艳红X-3B的光催化降解过程进行了探讨。结果表明:催化剂的主要成分为钙钛矿结构SrTiO_3,负载对SrTiO_3晶粒尺寸几乎没有影响。纯SrTiO_3没有明显的孔结构,负载后样品的比表面积和孔隙主要由HZSM-5提供。负载之后催化剂的降解活性显著提高,30%SrTiO_3/HZSM-5对活性艳红X-3B染料溶液的脱色和TOC去除速率最快。     

Functionalized,carbon nanotube material for the catalytic degradation of organophosphate nerve agents

Recent world events have emphasized the need to develop innovative, functional materials that will safely neutralize chemical warfare （CW） agents in situ to protect military personnel and civilians from dermal exposure. Here, we demonstrate the efficacy of a novel, proof-of-concept design for a Cu-containing catalyst, chemically bonded to a single-wall carbon nanotube （SWCNT） structural support, to effectively degrade an organophosphate simulant. SWCNTs have high tensile strength and are flexible and light-weight, which make them a desirable structural component for unique, fabric-like materials. This study aims to develop a self-decontaminating, carbon nanotube-derived material that can ultimately be incorporated into a wearable fabric or protective material to minimize dermal exposure to organophosphate nerve agents and to prevent accidental exposure during decontamination procedures. Carboxylated SWCNTs were functionalized with a polymer, which contained Cu-chelating bipyridine groups, and their catalytic activity against an organophosphate simulant was measured over time. The catalytically active, functionalized nanomaterial was characterized using X-ray fluorescence and Raman spectroscopy. Assuming zeroth-order reaction kinetics, the hydrolysis rate of the organophosphate simulant, as monitored by UV-vis absorption in the presence of the catalytically active nanomaterial, was 63 times faster than the uncatalyzed hydrolysis rate for a sample containing only carboxylated SWCNTs or a control sample containing no added nanotube materials.     

An improved process for the synthesis of VPI-5 molecular sieve

VPI-5 was synthesized with lesser time duration. The synthesized sample was characterized by XRD, SEM, FT-IR, TG/DTA,²⁷Al and³¹P MASNMR techniques, which shows that the synthesized sample was highly crystalline. Carbon and nitrogen analyses reveal that the sample contains no template molecules, however, TG/DTA analysis shows the presence of physisorbed template molecules. MASNMR results show the presence of three different types of aluminium and phosphorous. Two of them were present as in tetrahedral and the remaining one is present in octahedral environment.     

Zeolite molecular sieve 5A acts as a reinforcing filler, altering the morphological, mechanical, and thermal properties of chitosan

Chitosan-like bio-derived polymers possess a number of useful biological properties, but their mechanical and thermal durability needs to be improved to produce performance-driven materials. Inorganic particles are commonly used as fillers to provide reinforcement in polymer matrix. Zeolites are commercially important inorganic materials that are used extensively as adsorbents, ionic exchangers, and catalysts. One form of zeolite, known as molecular sieve 5A, is a Na⁺ and Ca²⁺ exchanged zeolite type A with a 1:1 Si:Al ratio. In this study, the role of zeolite as a reinforcing filler in a chitosan/malonic acid composite was investigated. The thermal stability, mechanical properties, and morphology of the chitosan matrix and chemical interactions within the composites were evaluated. It was observed that zeolite significantly improved the tensile strength, modulus, and thermal stability of chitosan and created a fibrous network-like morphology in the chitosan matrix. This study revealed that the inclusion of zeolite molecular sieve 5A improves the performance of chitosan-based biomaterials.     

立式分子筛吸附器二氧化碳穿透的分析及处理

60000 m3/h空分设备由于分子筛纯化系统蒸汽加热器泄漏,分子筛吸附器出口空气中二氧化碳含量超标,进而使主换热器通道因冻结阻力增大,空分系统被迫停车加温和分子筛特殊再生。介绍故障经过,分析二氧化碳穿透的原因,简述了处理措施和今后的经验教训。     

Thermal degradation kinetics and morphology of natural rubber/silica nanocomposites

A novel natural rubber/silica (NR/SiO2) nanocomposite with a SiO2 loading of 4 wt% is developed by incorporating latex compounding with self-assembly techniques. The SiO2 nanoparticles are homogenously distributed throughout the NR matrix as spherical nano-clusters with an average size of 75 nm. In comparison with the host NR, the thermal resistance of the nanocomposite is significantly improved. The degradation temperatures (T), reaction activation energy (E), and reaction order (n) of the nanocomposite are markedly higher than those of the pure NR, due to significant retardant effect of the SiO2 nanoparticles.     

一种新型自动深冷及活化分子筛的吸附泵设计

设计实现了一种新型自动深冷及活化分子筛的吸附泵.进行了吸附能力设计,采用基于PLC(可编程逻辑控制器)软硬件为核心的电气系统,方便地实现了对分子筛吸附泵的液氮自动输送以维持液氮量及分子筛活化的远程控制,有利于操作者操作和安全保障.验证实验结果表明,该分子筛吸附泵能快速吸附泄漏到密封容器里的有害气体,且吸附效果良好.     

On the synthesis of the aluminophosphate molecular sieve AIPO4-5

The possibility that formation and stabilization of tetrahedral Al is necessary for the synthesis of a pure AlPO₄-5 phase is examined in relation to the preparation of the reaction mixtures. The Al coordination in the reaction mixtures and products has been characterized by means of solid-state high-resolution ²⁷Al n.m.r. It is concluded that the role of the template (triethylamine) in the formation of AlPO₄-5 is to stabilize the newly created tetrahedral Al and to prevent conversion to octahedral Al by shielding from attack by water.