Papers by Keyword: High Specific Surface Area

Abstract: The hydrothermal synthesis of MCM-48 molecular sieves with CTAB and TEAOH as dual template agents and alkaline silica sol as silicon source has been systematically studied. The samples prepared at different crystallization temperature and time were analyzed by XRD, IR, nitrogen adsorption and desorption. The result shows that the best crystallization temperature and time are 100°C and 48h, respectively. According to BJH algorithm, the specific surface area of the sample is 1088 ~ 1669 m²/g, the pore size is 2.48 ~ 2.54 nm, and the pore volume is 1.2064 ~ 1.263 0cm³/g. Because it has high specific surface area, it can be widely used in catalytic adsorption, environmental engineering, biomedicine and other fields. Keywords: MCM-48; mesoporous molecular sieve; high specific surface area; dual template agents; alkaline silica sol

Abstract: This paper presents a new method of deposition of photocatalytic sorbent on nanofibers. This deposition uses controlled sublimation of water molecules from the vacuum-gel that is patent-protected. Silica gel nanostructures are precipitated by heterogeneous nucleation on the surface of nanofibres from an aqueous suspension of silicate nanoparticles and semiconductor carbon nitride (C₃N₄ ) or graphene nanosheets. After rapid solidification of gel (at least 10⁴ K/s), the nanofibers coated with the silica gel dispersion C₃N₄, or graphene are subjected to controlled sublimation at – 41 °C. This technology produced a nanofibrous material, which is stably coated with a highly porous silicate sorbent including dispersed photocatalytic nanoparticles. This textile material has a total sorption surface area of the order of hundreds m²/g. Unlike conventional sorbents, it is capable due to dispersed photocatalytic nanoparticles to regenerate sorption capacity by the absorption of visible light. The results of the preliminary research confirmed the high application potential of new controlled sublimation technology in the production of regenerable photocatalytic sorption fabrics.

Abstract: Bamboo as the raw material is carbonized to prepare high specific surface area activated carbon by microwave heating under nitrogen atmosphere in our present work. Influences of activation agents on the preparation of activated carbon are studied. The results show that activation agents have a significant influence on the preparation of activated carbon. Under the heating time of 15 min, the adsorption capacity of the activated carbon prepared utilizing KOH as activation agent is the best. When the KOH/C ratio is 4, the iodine number and yield of activated carbon are 2298 mg/g and 39.82%, respectively. The BET specific surface area, total pore volume and average pore diameter of activated carbon are 3441 m²/g, 2.093 ml/g and 2.434 nm, respectively. The micropore volume of 1.304 ml/g is 62.30% of total pore volume, indicating that the activated carbon is microporous activated carbon.

Abstract: The BN powder with high specific surface area was successfully prepared using an airtight high-temperature reactor with NH₃ as the reaction atmosphere and protective atmosphere. The influences of raw material ratio and reaction temperature on the specific surface area of obtained BN powder were investigated through the analysis on the powder yield, purity and specific surface area. The results shows both of raw material ratio and reaction temperature have influence on the specific surface area of BN powder. And the reaction temperature has more influence. More important, the BN powder with a specific surface area of 279.62m²/g and an average pore diameter of 4.19nm was obtained by the optimum process.

Abstract: This thesis is about preparing nano zinc oxide with multilayered cage-like structure by hydrothermal method, and characterizing the structure, composition, and the morphology of the product by means of XRD, SEM, EDS, TG-DTA, N2 absorption method and so on. The photocatalytic activities of ZnO with different morphologies have been evaluated. The result shows that, the multilayered cage-like nano ZnO has higher photocatalytic activity under the radiation of high-pressure mercury lamp; and its photocatalytic performance is better than ZnO nanorod. This method has following advantages: the process is simple and ecofriendly, it doesn't require the introduction of the surfactant, and it is convenient to be employed in mass production etc.

Abstract: Anatase TiO₂ having high temperature stability and specific surface area was synthesized using a gel precursor in very mild conditions. The precursor gel was obtained by dialysis treatment of Na₁₆Ti₁₀O₂₈–HNO₃ solution. The samples were characterized by X-ray diffraction analysis, transmission electron microscopy, Brunner–Emmett–Teller method for specific surface area measurements, and thermogravimetric analysis.

Abstract: High surface area activated carbon was prepared from waste tobacco after extracting nicotine with microbial enzymatic and chemical activation. Surface properties of the prepared carbons were performed using nitrogen adsorption, and the adsorption behavior of the prepared carbons under different operation conditions on methyl orange was investigated by a batch adsorption experiment. The experimental results show that: using waste tobacco 5.0035g and white- rot fungi volume is 2.0ml, under the conditions of enzymatic time of 36h, activation temperature at 600°C and activation time of 2h, the concentration of ZnCl₂ activation is 20%,The BET surface area of carbons prepared reach 1356.53m²/g, the average aperture is3.78nm, and the hole dimension is0.17 ml/g. The adsorption amount on methyl orange of 43mg/L reach 4979.31mg/g, and it show high adsorption capacity.

Abstract: A Pt-containing ordered mesoporous carbon with a high specific surface area was synthesized through evaporation-induced multi-constituent co-assembly method, wherein soluble resol polymer is used as the carbon precursor, silicate oligomers as the inorganic precursor, triblock copolymer as the template, and H2PtCl6•6H2O as the Pt precursor. After thermopolymerization, the template was removed by calcinations, and silica was removed by NaOH solutions. The resultant sample was characterized by X-ray diffraction, nitrogen sorption and transmission electron microscopy. The results showed that the carbon material exhibited highly ordered mesoporous structure, with a high specific surface area of 1560 m2/g, and the pore size distributions of the sample are very narrow, centering at around 6 nm; and the platinum particles with sizes of less than 8 nm were highly distributed in the carbon matrix. The high specific surface area may be ascribed to plenty of small pores inside carbon walls caused by the removal of silica from the composites. Interaction between the Pt4+ and the resin caused the Pt species to be incorporated into the framework of the resin, which was self-assembled into an ordering structure under the direction of the surfactant. After being subjected to pyrolysis at a high temperature, the Pt4+ ions were gradually reduced to form Pt nanoparticles, which were strongly imbedded in the carbon substrate and thereby thermally stable. The removal of silica may result in the exposure of Pt nanoparticles, which render Pt nanoparticles to contact easily with reactant molecules.