国产聚乙烯浆液催化剂工业应用

介绍了国产浆液催化剂(BCS 01)在Unipol气相法聚乙烯装置上工业化应用试验情况以及国产浆液催化剂的性能特点,并与其他催化剂进行了对比。BCS 01催化剂的活性为25～28kg/g。工业应用结果表明．国产浆液催化剂流动性能好,活性高,共聚能力强,所生产的聚乙烯产品均为优级品和一级品。     

催化剂载体硅胶的制备及应用

综述了载体硅胶在化工合成催化中的应用以及载体硅胶的制备技术，并介绍了载体硅胶的国内外生产研究现状及发展趋势。     

国产高效聚乙烯催化剂的工业应用

研究了国产催化剂在聚乙烯UNIPOL工艺中的应用，通过对比得出结论：国产高效催化剂完全可以替代进口UCCM-4520催化剂。     

国产气相聚乙烯浆液催化剂的工业应用

本文简要阐述了北化院BCS01和上海院SLC-S两种国产气相聚乙烯浆液催化剂的性能、催化剂结构,在Unipol聚乙烯工业装置上应用结果,以及和进口同类催化剂UCAT-J的性能比较.     

国产气相聚乙烯浆液催化剂的工业应用

本文简要阐述了北化院BCS01和上海院SLC-S两种国产气相聚乙烯浆液催化剂的性能、催化剂结构,在Unipol聚乙烯工业装置上应用结果,以及和进口同类催化剂UCAT-J的性能比较.     

国产气相聚乙烯浆液催化剂的工业应用

本文简要阐述了北化院BCS01和上海院SLC-S两种国产气相聚乙烯浆液催化剂的性能、催化剂结构,在Unipol聚乙烯工业装置上应用结果,以及和进口同类催化剂UCAT-J的性能比较。     

催化剂载体硅胶的扩孔研究进展

综述了近年来载体硅胶的扩孔研究情况，并对几种主要的扩孔方法进行了比较，认为复合荆扩孔方法效果较佳。     

硅胶负载型烯烃聚合催化剂的研究：Ⅳ化学活化对催化剂？…

ＳＥＭ观察发现了催化剂制备过程中颗粒的破碎和聚结现象,破碎随化学活化时三乙基铝量的增加而加剧,同时不安 现了细粒子和碎片在粒径较大催化剂颗粒表面的聚结现象,发生聚结的细粒子或碎片的粒径一般在２０μｍ以下,破碎和聚结都破坏了催化剂的宏观形态,较多的三乙基铝量也改变了催化剂颗粒表面的微观形态,局部表面形成了絮团状物质。     

Investigation of acrylonitrile polymerization on the surface of porous microspherical silica gel

The kinetics of acrylonitrile polymerization on the surface of porous microspherical silica gel (PMSS) was studied and some kinetic parameters were determined. The structure of PMSS-based sorbents was analyzed by FTIR-spectroscopy, XRD and sorption analysis before and after microcapsulation with polyacrylonitrile.     

Synthesis of stable ACC using mesoporous silica gel as a support

Stable amorphous calcium carbonate supported by mesoporous silica gel was successfully synthesized. The silica gel support is prepared through the hydrolytic polycondensation of ethyl silicate under suitable conditions. Laser scanning confocal microscopy (LSCM) observations reveal that the morphology of the products is branched with cruciform-like and flower-like structure. Raman spectroscopic analysis and scanning electron microscopy (SEM) observation of the products confirm the combination of stable amorphous calcium carbonate (ACC) nanoparticles and mesoporous silica gel. A possible growth mechanism for the branched structure has been proposed. Results indicate potential application of this work to ACC storage, crystal engineering, biomimetic synthesis, etc.     

An electroanalytical application of 2-aminothiazole-modified silica gel after adsorption and separation of Hg(II) from heavy metals in aqueous solution

2-Aminothiazole covalently attached to a silica gel surface was prepared in order to obtain an adsorbent for Hg(II) ions having the following characteristics: good sorption capacity, chemical stability under conditions of use, and, especially, high selectivity. The accumulation voltammetry of mercury(II) was investigated at a carbon paste electrode chemically modified with silica gel functionalized with 2-aminothiazole (SIAMT-CPE). The repetitive cyclic voltammogram of mercury(II) solution in the potential range −0.2 to +0.6 V versus Ag/AgCl (0.02 mol L⁻¹ KNO₃; v=20 mV s−1) show two peaks one at about 0.1 V and other at 0.205 V. The anodic wave peak at 0.205 V is well defined and does not change during the cycles and it was therefore further investigated for analytical purposes using differential pulse anodic stripping voltammetry in differents supporting electrolytes. The mercury response was evaluated with respect to pH, electrode composition, preconcentration time, mercury concentration, “cleaning” solution, possible interferences and other variables. The precision for six determinations (n = 6) of 0.02 and 0.20 mg L⁻¹ Hg(II) was 4.1 and 3.5% (relative standard deviation), respectively. The detection limit was estimated as 0.10 μg L⁻¹ mercury(II) by means of 3:1 current-to-noise ratio in connection with the optimization of the various parameters involved and using the highest-possible analyser sensitivity.     

Adsorption equilibria of benzoic acid on silica gel from supercritical carbon dioxide

Supercritical fluids, especially carbon dioxide, are increasingly used as carriers for adsorption-desorption processes, particularly in the pharmaceutical industry. Nevertheless, equilibria data for such processes are rather limited. Therefore, in this work, the adsorption equilibria of benzoic acid onto non-modified silica gel from scCO₂ were evaluated by Supercritical Fluid Chromatography applying the Peak Maxima method. Solubility of benzoic acid in scCO₂ was enhanced by addition of 2-propanol.The effects of modifier content, temperature and pressure on the solute loading were investigated. Experimental data were best described by the cubic Hill isotherm model, which accounted for the change of curvature of the elution profiles observed as concentrations in the mobile phase increased. For the concentration range reached in this study (up to 6 mg/mL), adsorption of benzoic acid was favoured at low modifier contents, high temperatures and low pressures, conditions at which the solvating power of the modified scCO₂ decreased.     

硅胶的发展现状及应用

硅胶的化学性质稳定、吸附性能高、热稳定性好、较高的机械强度,是一种高活性多孔材料。硅胶生产方法很多,以硅酸钠和无机酸为原料的溶胶-凝胶法应用最为广泛。硅胶改性包括硅胶扩孔和硅胶负载,改性后的硅胶,性能优良,应用更为广泛。硅胶负载金属镍是一种很好的脱除油品中氮化物的吸附剂,金属负载量、吸附温度、吸附时间不同,硅胶吸附脱氮的效果也不同。目前,硅胶已经广泛应用到各行各业,硅胶在石油化工、医药、食品、油墨、农业的应用发展迅速。     

Novel surface ionic imprinting materials prepared via couple grafting of polymer and ionic imprinting on surfaces of silica gel particles

In this paper, a new surface molecular imprinting technique is put forward, and a kind of novel ion-imprinted polymers (IIPs) were prepared through a new approach: firstly functional macromolecule polyethyleneimine (PEI) was grafted onto the surfaces of silica gel particles via the coupling grafting method (“grafting to” method) and the composite material PEI/SiO₂ with chemical linking was formed; secondly the ionic imprinting was carried out towards the macromolecule PEI grafted on the surface of silica particles using Cu²⁺ or Cd²⁺ ion as a template, epichlorohydrin (ECH) as a crosslinking agent and by coordination linkage actions, and Cu²⁺ ion (or Cd²⁺ ion)-imprinted material IIP-PEI/SiO₂ was prepared. The binding characteristics of IIP-PEI/SiO₂ for Cu²⁺ ion (or Cd²⁺ ion) were studied in detail by adopting both static and dynamic methods. The experimental results show that the ion-imprinting material IIP-PEI/SiO₂ has specific recognition ability for the template ions, and this character displays mainly in two aspects: (1) it has high affinity for the template ions, its binding amounts for the template ions are much greater than that of the non-imprinted composite material PEI/SiO₂, and the adsorption capacity enhances nearly two times compared to PEI/SiO₂; (2) it has excellent selectivity for the template ions, for the IIP-PEI/SiO₂ by using Cu²⁺ as template ion, its selectivity coefficients relative to Zn²⁺ and Ni²⁺ are 80.21 and 86.08, respectively, and for the IIP-PEI/SiO₂ by using Cd²⁺ as template ion, its selectivity coefficients relative to Cr³⁺ and Pb²⁺ are 77.05 and 88.22, respectively. Besides, the imprinting material IIP-PEI/SiO₂ has a fine elution property using HCl solution as eluent. The obtained imprinting material by using the new surface molecular imprinting techniques possesses superexcellent binding property for template molecules or ions because of the distribution of imprinted cavities in a thin polymer layer and smaller diffusion barrier.     

Investigation of the filtration rate of silica in aluminum fluoride production from silicic acid

The effect of some influencing parameters such as temperature, initial concentration of flusilicic acid, rate of addition of Al(OH)₃ powder, agitation speed and aging time of slurry and their mixed effects on the filtration rate of silica precipitates have been investigated. Moreover, a suitable model is presented to describe the formation mechanism of aggregated silica precipitates which can well explain the effect of different factors on the filtration rate of the silica precipitates.     

Adsorption characteristics of Cr(III) ionic imprinting polyamine on silica gel surface

In this paper, a kind of ionic imprinting polyamine (IIP) was prepared through an advanced approach. Firstly, functional macromolecule polyethyleneimine (PEI) was grafted onto the surfaces of silica gel particles, and the PEI/SiO₂ was formed. Secondly, the ionic imprinting process was carried out using Cr³⁺ ion as a template, and epichlorohydrin (ECH) as a crosslinking agent, and Cr³⁺ ionic imprinting polyamine IIP-PEI/SiO₂ was prepared. The adsorption properties of IIP-PEI/SiO₂ for Cr³⁺ ion were studied in details by adopting both static and dynamic methods, and the effects of main imprinting conditions, such as the concentrations of Cr(III) ion and the amount of ECH, on the adsorption property of the imprinted material IIP-PEI/SiO₂ were examined. The experimental results show that the IIP-PEI/SiO₂ has high affinity and excellent selectivity for the template ion. Its adsorption amounts for template ion enhances nearly two times compared to PEI/SiO₂, and its relative selectivity coefficients relative to Zn²⁺ and Pb²⁺ are 24.63 and 59.32 respectively. Besides, the IIP-PEI/SiO₂ has a fine elution property using HCl solution as eluent.     

Preparation of microstructure compatible porous supports by sol–gel synthesis for catalyst coatings

To enhance the inner surface of microchannel reactors, porous metal oxide coatings based on alumina, silica, and titanium oxide have been developed as support for catalytically active components. The oxides were made by the sol–gel process. Thin film coating was accomplished by dip coating using an Fe-based alloy as support. The influence of the sol composition, sol viscosity, and thermal treatment procedure on the surface enhancement factor and the porosity of the coating was investigated. The resulting surface enhancement factor reached 800 m²/m².     

Application of silica gel as an effective modifier for the voltammetric determination of dopamine in the presence of ascorbic acid and uric acid

Amorphous silica gel modified carbon paste electrode (CPE) offers substantial improvements in voltammetric sensitivity and selectivity towards determination of dopamine (DA). Cyclic voltammetry of Fe(CN)₆^3−/4− as a negatively charged probe revealed that the surface of the silica gel modified carbon paste electrode had a high density of negative charge at pH 8.0. Therefore, the modified electrode adsorbed DA (pK_a = 8.9) and enhanced its voltammetric response while repulsed ascorbic acid (AA) (pK_a = 4.2) and uric acid (UA) (pK_a = 5.4) and inhibited their interfering effects. The influence of various experimental parameters including percent of silica gel in the CPE, pH of solution, and accumulation time and potentials, on the voltammetric response of DA was investigated. At the optimum conditions, the analytical curve was linear for dopamine concentrations from 2.0 × 10⁻⁷ to 1.0 × 10⁻⁶ mol L⁻¹ and 2.0 × 10⁻⁶ to 1.5 × 10⁻⁴ mol L⁻¹ with a detection limit (3σ) of 4.8 × 10⁻⁸ mol L⁻¹. The prepared electrode was used for determination of DA spiked into DA injection and human serum samples, and very good recovery results were obtained over a wide concentration range of DA.