介孔炭作为加氢脱硫催化剂载体材料的研究

以介孔硅SBA-15为模板,焦糖和呋喃醇为碳源,通过多种浇注法制备介孔炭材料.采用低温氮吸附、透射电镜和X射线小角衍射分析模板及介孔炭的织构.结果显示合成的介孔炭成功地复制了SBA-15的结构.以制备的介孔炭作载体担载钴钼合成了加氢脱硫催化剂,利用X射线能谱、透射电镜能量分布谱及一氧化氮化学吸附评估了催化剂的活性及活性点分布,结果表明介孔炭担载的催化剂活性高于活性炭担载的同类催化剂.     

Nickel nanoparticles decoration of ordered mesoporous silica thin films for carbon nanotubes growth

We report in situ successive depositions of nickel nanoparticles and carbon nanotubes (CNTs) on ordered mesoporous silica films used as template for the catalyst particles. The mesoporous films are synthesized by the evaporation-induced self-assembly process from tetraethyl orthosilicate derived oligomers and a di-block copolymer from dip-coating deposition method. The substrates are decorated with Ni nanoparticles through Ion Beam Deposition and posterior annealing to induce metal coalescence in the mesoporous cavities. CNTs were then grown by Chemical Vapor Deposition in the presence of an electric field. These techniques provide a simple control method producing ordered arrangements of catalyst nanoparticles and ordered nanostructures for large area applications.     

Preparation of mesoporous carbon from biomass for heavy metal ion adsorption

Mesoporous carbon (MC-S) has been synthesized via a facile hydrothermal method by using cheap and nontoxic soluble starch as carbon precursor, Pluronic copolymer as soft templates. In the process of hydrothermal synthesis, the soluble starch can hydrolyze to give glucose, which can assemble with Pluronic copolymer through hydrogen bond interactions. Glucose further dehydrates and cross-links to form polymer networks. After carbonization of the polymer networks, MC-S can finally be obtained. The obtained MC-S has a specific surface area of 439 m² g^?1, uniform pore size of 4.5 nm as well as high oxygen content of 23.32%. The MC-S exhibits a good adsorption for heavy metal ions superior to FDU-15 due to the oxygen functional groups.     

Nonionic surfactant-templated mesoporous carbon as an electrocatalyst support for methanol oxidation

Two carbons were synthesized for use as platinum electrocatalyst supports for methanol oxidation. For both materials, furfuryl alcohol was used as the carbon precursor; however, one (CPEG) was made using poly ethylene glycol as the pore former, while the other (CSRF) was produced using Pluronic^® F127 as the soft template by organic–organic self-assembly. The CPEG and CSRF carbons were estimated from nitrogen physisorption experiments to be micro- and mesoporous, respectively. Platinum nanoparticles were deposited on each carbon as well as on Vulcan XC-72 carbon by the formic acid reduction method. The physicochemical properties of electrocatalysts were studied using X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy dispersive X-ray analysis (EDX), and their electrochemical features were examined using cyclic voltammetry, chronoamperometry, and impedance spectroscopy. It was found that higher methanol oxidation peak current densities as well as lesser charge transfer resistance at electrode/electrolyte interface were obtained for Pt supported on CSRF as compared to those on Vulcan XC-72 carbon, owing to the higher specific surface area and larger total pore volume (696 m² g⁻¹ and 0.60 cm³ g⁻¹, respectively) together with superior electrical conductivity of mesoporous CSRF. On the other hand, the lower surface area and pore volume of microporous CPEG substrate confined Pt nanoparticles deposition and thus made CPEG-supported Pt an inefficient methanol oxidation electrocatalyst.     

通过再活化浸渍金属盐的活性炭来发展中孔结构

研究了在椰子壳活性炭上浸渍金属盐（硝酸铁和硫酸铁）后，在二氧化碳气氛中催化活化对中孔结构的影响。发现硝酸铁对活性炭比表面积（-1930m^2／g）的增加和中孔结构（-10nm）的发展更有效。改性活性炭具有发达的中孔结构，显示了更大的维生素B12吸附容量（是改性前的5倍～8倍）和更快的吸附速度。中孔结构的发展基于三个方面的原因：（1）在活化过程中，浸渍在活性炭微孔内的金属盐分解所释放的氧化性气体与微孔碳壁反应，扩大了孔径；（2）在高温下，来自于金属盐的金属氧化物被碳还原，扩大了孔径；（3）在金属铁存在下，碳壁被催化活化，大大提高了活性炭的中孔率。由此提供了一种廉价的从商业活性炭制备中孔活性炭的有效途径。     

双电层电容器用中孔炭微球/活性炭复合电极的制备

采用水热法合成比表面积1850m2/g、粒径lμm的中孔炭微球(MCM);而后将所制MCM加入比表面积为3200m2/g的超级活性炭(HSAC)中制成用于双电层电容器的复合电极材料,并研究了该复合电极材料的电化学性能.结果表明:在比表面积为3200m2/g的HSAC中添加质量分数20%的MCM后,其颗粒接触内阻、离子扩散内阻明显降低;在6mol/L的KOH电解液体系中,在12A/g的电流密度下,其比电容仍能稳定在230F/g.而在同样的条件下,纯HSAC和纯MCM的比电容仅分别为190F/g和148F/g.复合电极在大电流下电化学性能的提高应归因于MCM合适的粒径、中孔结构及其较高的比表面积.     

Efficient desulfurization of fuel with functionalized mesoporous carbon CMK-3-O and comparison its performance with mesoporous carbon CMK-3

In this work, a functionalized mesoporous carbon (CMK-3-O) was synthesized after oxidation with nitric acid and was used to adsorb dibenzothiophene (DBT) from model oil for the first time. Then, its performance was compared with that of CMK-3. The functionalized mesoporous carbon, CMK-3-O, showed better a capacitance performance for DBT adsorption than that of CMK-3. The maximum adsorption capacity was obtained for functionalized mesoporous carbon at optimum conditions with 6 M HNO₃ aqueous solution and 30 min contact time. The physical and structural properties of CMK-3-O and CMK-3 were investigated with X-ray diffraction method (XRD), N₂ adsorption–desorption isotherm, FT-IR, and elemental analysis (CHNO). Results of the elemental analysis showed that the oxygen and nitrogen content has increased and the carbon content has decreased through oxidation treatment. The effects of various factors on the adsorption process (such as temperature, amount of adsorbent, contact time, and concentration) of DBT were studied. CMK-3-O showed a maximum adsorption capacity of 86.96 mg DBT g^?1 of CMK-3-O at optimized conditions (temperature, 25°C; adsorbent dosage, 20 g L^?1; contact time, 60 min), which was a higher adsorption capacity of that observed for CMK-3 (57.47 mg DBT g^?1 of CMK-3). Kinetic studies have revealed that the adsorption of DBT can be described by a pseudo-second-order rate equation. Equilibrium data showed that adsorption process was best represented by the Langmuir model. The results also illustrated the fact that the regenerated adsorbent afforded 64.3% of the initial adsorption capacity after the two regeneration cycles.     

双模板结构导向剂制备有序介孔炭

以间苯二酚/甲醛制备的酚醛树脂为碳前躯体,三嵌段共聚物F127和P123作为主辅结构导向剂,采用有机-有机自组装的方法制备有序介孔炭(Ordered mesoporous carbons,简称OMCs)。采用X射线衍射仪、透射电镜和N2吸/脱附手段对所制OMCs进行表征,研究了反应时间以及主辅模板剂的比例对介孔孔道结构的影响。结果表明,随着反应时间从24h延长至72 h,介孔炭有序性先增后减;当主辅模板剂F127/P123摩尔比为0.002 7∶0.002 7时,所得介孔炭有序性较好,为P6mm型孔道结构,介孔孔容和比表面积分别为0.59 cm3/g和640.34 m2/g,平均孔径为3.68 nm.     

结构有序、双重孔隙中孔炭材料的合成与表征

采用纳米涂层技术,以介孔分子筛SBA 15为模板,在其纳米孔道内引入糠醇/草酸溶液,经原位聚合,炭化后制得炭/SBA 15复合物。采用化学法脱除模板后制得具有规则结构的中孔炭。高分辨TEM表征结果显示该中孔炭是由纳米炭管相互联接、堆积而成,且具有六方对称结构。氮吸附结果显示其比表面积高达2000m2/g,孔径呈双峰分布。孔径相对较大的孔隙来源于SBA 15孔道经纳米涂层后所保留的孔隙;孔径相对较小的孔隙来源于SiO2移除后遗留的纳米孔空间。该方法可应用于以其他多孔氧化硅为模板制备新型纳米复合物的研究过程。     

Features of obtaining an effective catalyst for synthesis of carbon nanostructured materials

Abstract

In the present paper, the features of obtaining a metal oxide Fe–Co/Al₂O₃ catalyst for the synthesis of carbon nanostructured materials through thermal decomposition are considered. It was experimentally proved that the temperature and duration of the stage of thermal decomposition of the initial components solution significantly affect the catalyst activity in the synthesis of carbon nanostructured materials by the CVD method. It was found that controlling the mode parameters of the thermal decomposition of the initial components solution of the Fe–Co/Al₂O₃ catalyst, one can not only obtain a catalyst with the required characteristics but also directionally synthesize carbon nanostructured materials over the resulting catalytic systems. During the experiments, rational modes for the implementation of the method for producing catalysts were determined, allowing to form a metal oxide system with a specific surface area of 108?m²/g, the use of which in the synthesis of carbon nanostructured materials leads to the formation of multi-walled carbon nanotubes with an external diameter of 30?nm.     

Effects of sol aging on mesoporous silica thin films organization

Cetyltrimethylammonium bromide (CTAB) templated mesoporous silica thin films were deposited on glass slides by evaporation-induced self-assembly (EISA) process using a dip-coating method. The effects of sol aging on the mesophase structure of the thin films organization were investigated. Identification of the structures was accomplished by coupling X-ray diffraction (XRD) and transmission electron microscope (TEM) investigations, and corresponding sol was characterized by ²⁹Si solution state nuclear magnetic resonance (²⁹Si NMR) and UV-Vis spectrophotometer for studying the mesophase structure evolution. Results indicate that sol aging has great effects on the mesophase structure of the films organization, which includes degree of order and phase transformation of mesoporous silica thin films. To obtain a better understanding of the effects of sol aging on the mesophase structure, the theories of apparent mass fractal dimension and charge density matching were introduced to explain the self-assembly process.     

Using phenol–formaldehyde resin as carbon source to synthesize mesoporous carbons of different pore structures

In this research communication, we performed the phenol–formaldehyde (PF) resin as an alternative carbon source and various mesostructured silicas as the nano-templates to conveniently prepare the mesoporous carbons of high surface area (850–1500 m² g⁻¹), large pore size (2.0–22.0 nm) and great pore volume (0.65–1.15 cm³ g⁻¹). It was reasonably supposed that there exist interaction matching between the negative-charged silica surface of the silica template and PF resin. Therefore, the PF oligomers could be homogeneously adsorbed into the nanochannels or cages of the mesoporous silicas via an impregnation process. Because the thermosetting PF resin only requires a simple heat treatment process at 100 °C to form the cross-linked polymeric structure, the replication of the mesostructure of the mesoporous silica template could be readily achieved without adding any polymerization catalysts.     

Hybrid surfactant-templated mesoporous silica formed in ethanol and its application for heavy metal removal

With cetyltrimethylammonium (CTAB) and tetramethylammonium hydroxide (TMAOH) as hybrid surfactant templates, a mesoporous adsorbent (adsorbent C) was synthesized in ethanol via the integration of "One-step" procedure and "Evaporation-Induced Self-Assembly" procedure. During the synthesis, TMAOH served as the subsidiary structure-directing agent. Adsorbent C exhibited higher pore diameter (centered at 6.1 nm), BET surface area (421.9 m(2)/g) and pore volume (0.556 cm(3)/g) than the other two adsorbents only using P123 (adsorbent A) or CTAB (adsorbent B) as the surfactant. The adsorbents were also characterized by XRD and FTIR spectroscopy. The adsorption of copper, zinc, lead, iron, silver and manganese ions on adsorbent C was investigated by contrast tests with adsorbent A and B. The experimental data showed that adsorbent C possessed better adsorption properties than the counterparts. The order of adsorption capacity for six metal ions was Mn(2+)相似文献   

Effective NH2-grafting on mesoporous SBA-15 surface for adsorption of heavy metal ions

Utilizing the reactions between toluene diisocyanate (TDI), silanol, and ethylenediamine (EDA), NH₂ groups were successfully grafted on mesoporous SBA-15 surface without any destroy to the mesostructure. TDI was employed as a ‘bridge’ molecule whose one NCO group was used to link SBA-15 surface silanols and the other one was left to link EDA. Such NH₂-grafting is highly effective for a high loading amount of NH₂ groups on SBA-15 because the special stepwise grafting can avoid amino/silanol and amino/amino interactions. Subjected to remove toxic heavy metal ions in aqueous solution, the obtained NH₂-SBA-15 showed very high adsorption rates 99.4%, 100%, 99.7%, 98.7% and 99.9% for Cu²⁺, Zn²⁺, Cr³⁺, Ni²⁺ and Cd²⁺, respectively, which should be attributed to the strong complexation reactions between metal ions and grafted NH₂ groups.     

炭材料负载金属催化剂在活化过硫酸盐中的应用进展

近年来,基于硫酸根自由基的高级氧化技术在环境污染治理中的应用受到越来越广泛的关注,而炭材料负载金属催化剂在活化过硫酸盐去除环境污染物方面展示出巨大的优势。全面总结了炭材料负载金属离子、金属单质、金属氧化物等而制备的不同催化剂在活化过硫酸盐中的作用机制以及对污染物的降解效果等方面的研究进展,并指出了该类催化剂在活化过硫酸盐氧化中的应用前景与未来的研究方向。     

The effect of carbon precursor on the pore size distribution of mesoporous carbon during templating synthesis process

The starch and cyclodextrin were selected as the precursors and the mixture of surfactant and tetraethyl orthosilicate (TEOS) as template to prepare mesoporous carbon. The result showed that a bimodal pore size distribution in mesoporous carbon derived from starch appeared; one was around 3.4 nm and the other ranged from 3.8 to 16.2 nm. However, there existed a concentrated pore size distribution from 3.2 to 4.2 nm in mesoporous carbon derived from cyclodextrin. The different molecular structure of starch and cyclodextrin and their polymerization process in the presence of sulfur acid were responsible for the resulted mesoporous carbon structure; the starch could polymerize by head to head or side by side, but the cycleodextrin was only polymerized by head to head.     

基于可再生植物多酚的介孔炭材料合成及其环境和能源应用

介孔炭材料具有高比表面积、可调的组成和孔结构、良好的化学稳定性和导电性,被广泛用于环境、催化、能源等领域.碳源是介孔炭合成的关键.植物多酚,作为一种生物质碳源,具有低价、无毒、可再生的优点.且植物多酚具有黏附性和金属络合能力,被广泛用于合成介孔炭复合材料.尽管该领域已取得巨大进展,但关于植物多酚衍生介孔炭的综述还很少....     

Orientation enhancement of polycrystalline ZnO thin films through thermal oxidation of electrodeposited zinc metal

The polycrystalline ZnO thin films with (002) orientation enhancement were prepared by annealing of electrodeposited metallic Zn films from the ethylene glycol solution of zinc acetate without using any catalyst and template. The morphologies of the thin films were evolved from the nanoplate to the nanocolumn structures with increasing of annealing temperature from 100 °C to 500 °C. SEM and XRD studies indicated that the ZnO nanocolumns were enhanced in the (002) orientation along their length direction. The UV-vis absorption spectra of the ZnO films obtained by annealing at 300 °C and 500 °C were carried out and their band gaps were 3.18 eV and 3.20 eV, respectively. A possible growth mechanism of the ZnO nanostructures responsible for the morphologies and orientation evolution was discussed.     

Fabrication of Ni nanoparticles on ordered mesoporous carbon using an immersion-electrodeposition method

Ni nanoparticles have been fabricated on the surface of CMK-3 mesoporous carbon through an immersion-electrodeposition (IE) technique. Transmission electron microscopy analysis indicated that it was a facile approach to electrochemically prepare nano-sized Ni clusters. The electrocatalytic properties of Ni/CMK-3 nanocomposites electrode for hydrogen evolution reaction have been investigated by liner scanning voltammetry in alkaline solution, and high electrocatalytic activity was observed. Therefore, for the first time, we report this IE method as a new route to prepare metal/CMK-3 nanocomposites which have potential applications in the catalytic field.     

Synthesis and characterization of mesoporous silica thin films as a catalyst support on a titanium substrate

Mesoporous silica films with a thickness of 500-900 nm were synthesized on a titanium substrate by the evaporation-induced self-assembly method (with 900-1200 rpm for 90 s) using cetyltrimethylammonium bromide (CTAB) as structure-directing agent and tetraethyl orthosilicate as the silica source. Prior to coating deposition, the titanium substrate was oxidized to increase the surface roughness up to 500 nm and to produce a thin titania layer. Just before the synthesis, the titania layer was made super hydrophilic by an UV treatment for 2 h to provide a better adhesion of the silica film to the substrate. Films with hexagonal and cubic mesostructures with a uniform pore size of 2.8 nm and a surface area of 1080 m²/g were obtained and characterized by different methods. An alternative approach for surfactant removal by gradual heating up to 250 °C in vacuum was applied. Complete removal of CTAB from the as-synthesized silica films was confirmed by infrared spectroscopy.