由微孔棒状羟基磷灰石为模板合成的新型层次孔炭材料的电化学电容性能

电化学电容器已经成为极具潜力的可满足高功率需求的储能系统器件. 多孔炭具有大比表面积、高导电性、化学惰性、廉价及可调孔结构等优势, 因此成为电化学电容器最为常用的电极材料. 本文报道由微孔棒状羟基磷灰石为模板及蔗糖为碳源合成的新型具有层次孔道结构的孔炭材料的电化学电容器的性能. 采用X射线衍射分析仪、扫描电子显微镜、透射电子显微镜、X射线光电子能谱及BET表面分析仪表征了合成的多孔炭的形貌及表面特性. 采用循环伏安法、交流阻抗图谱分析及恒流充放电评价多孔炭材料在1 mol·L^-1硫酸中的电化学电容性能. 多孔炭具有高的比表面积(719.7 m²·g^-1)和大的孔容(1.32 cm³·g^-1), 其无序的孔道由任意分布的微孔、坍塌的中孔及类模板形状的相互交织的棒状中孔组成. 随着炭化温度的增加, 微孔及棒状中孔的密度随之降低, 在炭化温度高达900℃时, 孔径分布图上出现了三个峰. 正是由于这些特殊的结构特征, 由900℃炭化得到的多孔炭制成的电极展示出很好的电化学电容性能.     

微孔-介孔多级孔炭材料的制备及电化学电容性能研究

采用有机-有机自组装法, 并结合后活化法制备了一类具有微孔-介孔复合孔结构的多级孔炭材料(HPC), 并研究了这类材料的电化学电容性能. 孔结构测试表明, 采用KOH后活化法可以在介孔炭的孔壁上控制性地生成微孔. 电化学测试表明, 与文献中报道的硬模板法制备的介孔炭相比, HPC具有更好的电化学电容性能. 在100 mV/s的快速电压扫描速率下, 它的比电容值能达到168.9 F/g. 更值得指出的是, HPC的高频电容性能非常优异, 在1 Hz时的比电容值高达180 F/g, 这一数值优于任何其它类的电极材料. HPC优异的电化学电容性能应当归功于它特殊的多级孔结构, 有助于电解质离子在孔道内的快速扩散.     

介孔炭的直接制备及其电化学性能研究

以柠檬酸镁为原料,采用直接碳化法制备介孔炭电极材料。N2吸附测试表明,所制备多孔炭的比表面积达2 000 m2·g-1左右,介孔孔容和平均孔径随着炭化温度的升高而增加,当炭化温度大于800℃时,能够制备出以介孔结构为主的多孔炭材料。电化学测试表明,MgC-800和MgC-900具有优异的电化学电容特性。与硬模板法制备的OMC相比,MgC-800和MgC-900在实验电流密度范围内具有更大的比电容值,这应当归功于它们巨大的比表面积以及有利于电解质离子扩散的介孔结构。     

可调有序介孔炭在有机和硫酸电解液中的电容性质

采用硬模板法, 掺杂硼酸制备了一系列有序介孔炭材料, 并研究了其在有机和硫酸电解液中的电容性质. 结构分析表明, 该类炭材料具有平行排列的有序介孔孔道, 随硼酸摩尔分数从0增大至50%, 炭材料孔径尺寸从3.3 nm增大至5.7 nm, 表面含氧量从2.0%增大至5.2%(摩尔分数). 电化学测试表明, 在有机电解液中, 炭材料的电容性能主要是双电层电容, 含氧官能团没有引入明显的赝电容. 在硫酸电解液中, 掺杂5%硼酸制备的有序介孔炭材料BOMC-5的质量比电容值最大, 为140.9 F·g^-1; 随含氧量增大, 炭材料单位面积比电容值增大, 掺杂50%硼酸制备的炭材料BOMC-50的单位面积比电容值达到0.17 F·m^-2, 说明含氧官能团在硫酸电解液中引入明显的赝电容. 炭材料的表面化学性质决定了材料表面与电解液的浸润性, 是影响炭材料比电容保持率的主要因素.     

微孔/介孔复合分子筛的合成及其对CO2的吸附性能

采用两步晶化法将合成的沸石前驱液(S)或沸石固体粉末(P)经不同浓度(c)的NaOH处理后, 分别以表面活性剂十六烷基三甲基溴化铵(CTAB)软模板或介孔炭(Meso-C)硬模板为导向剂, 自组装合成S-β-MCM41(c)、P-β-MCM41(c)、P-ZSM-MCM41(c)、P-ZSM-C系列微孔/介孔复合分子筛. 考察了沸石分子筛种类、碱处理液浓度以及介孔模板剂对合成复合分子筛结构与性能的影响. X射线衍射(XRD)、透射电子显微镜(TEM)和氮气吸附-脱附表征结果表明产物具有微孔/介孔多级孔结构. 该材料对CO₂的吸附能力比纯微孔或介孔材料均有明显提高, 其中P-ZSM-MCM41(2)的CO₂吸附容量最大可达1.51 mmol·g^-1, 为ZSM-5沸石吸附量的两倍多.     

孔径渐变的有序介孔炭的合成及电化学应用

以SBA-15为模板,硼酸为孔道扩张剂,蔗糖为碳源制备了一系列孔径渐变的有序硼杂介孔炭材料,并研究了其电化学电容性能。氮气静态吸附测试表明,当硼酸物质的量分数从0%增大到75%时,介孔炭的孔径从3.3nm增大至8.1nm,并保持有序的介孔结构。电化学测试表明,在KOH电解液中,硼杂介孔炭比电容明显高于未掺杂硼有序介孔炭,孔道有序性和孔径大小共同影响了炭材料的电容性能。当硼酸物质的量分数为50%时,炭材料的比电容性能最优。     

介孔氧化镍的合成、表征和在电化学电容器中的应用

以十二烷基硫酸钠为模板剂, 采用尿素为沉淀剂, 用均匀沉淀法, 适当控制尿素的水解速度, 制备具有介孔结构的氢氧化镍胶体, 在不同温度下焙烧处理得到孔分布集中的氧化镍介孔分子筛. 结果表明, 在523 K下焙烧得到的氧化镍BET比表面达到477.7 m²•g^－1. 结构表征还显示, 介孔氧化镍的孔壁为多晶结构, 其孔结构形成机理应为准反胶束模板机理. 循环伏安法表明用NiO介孔分子筛制备的电极有很好的电容性能. 与浸渍法和阴极沉淀法制得的NiO相比, 这种介孔结构的NiO能够大量用来制作电化学电容器电极, 并且保持较高的比电容量和良好的电容性能.     

马铃薯淀粉基微孔炭微球的制备及其电化学性能

以存在广泛的生物质原料马铃薯淀粉为前驱体, 通过磷酸对淀粉分解的促进作用和KOH活化法制备微孔炭微球材料. 采用77 K条件下的N₂吸附、扫描电子显微镜(SEM)分别对所得样品的孔隙结构、形貌特征进行表征. 采用傅里叶变换红外(FT-IR)光谱对磷酸促进淀粉分解的机理进行研究. 在6 mol·L^-1 KOH 电解质溶液中的电化学测试表明了所得微孔炭微球材料的优异电容特性. 在50 mA·g^-1的电流密度下, 电容量为363.6 F·g^-1. 此外, 该材料表现出了优异的倍率性能, 在扫描速率为300 mV·s^-1的条件下, 所得循环伏安(CV)曲线仍能保持良好的矩形形状. 电化学测试结果表明, 马铃薯淀粉基微孔炭微球材料在高性能电化学电容器的电极材料领域具有广阔的应用前景.     

基于羧甲基纤维素钠制备氮掺杂多孔炭及其电容性能研究

以羧甲基纤维素钠(NaCMC)为碳源, 利用直接炭化工艺(无需进一步活化)制备多孔炭材料; 然后, 以CO(NH₂)₂为氮源, 形成了氮掺杂多孔炭材料. 氮的存在形式包括吡啶N、石墨N和吡咯N. 实验结果表明, 羧甲基纤维素钠与CO(NH₂)₂之间的配比可以有效控制氮存在形式、含量、样品的比表面积及孔的结构等. 样品的电化学性能测试表明, 氮掺杂后多孔炭材料的超电容性能得到了显著提升. 以carbon-N-1:20为例, 其比表面积可达858 m²·g^-1, 远高于未经氮掺杂carbon-blank 的463 m²·g^-1, 其质量比电容则由94.0 F·g^-1提高到了156.7F·g^-1.     

氮掺杂介孔碳的制备及其电化学超电容性能

通过直接炭化沸石咪唑酯骨架结构材料（ZIF-8）纳米多面体,成功制备了氮掺杂介孔碳（NMCs）. 采用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线衍射（XRD）、拉曼光谱、X射线光电子能谱（XPS）及比表面和孔隙度分析仪对其微观形貌和结构进行了表征,并对NMCs的电化学超电容性能进行了测试. 结果表明：NMCs具有规整的形貌、介孔纳米结构和较大比表面积（2737 m²·g^-1）;由于氮元素掺杂所赋予的优异的表面润湿性和赝电容性能,且介孔结构有利于电解质到达电极活性材料表面,NMCs表现出优异的电化学超电容性能,在1 A·g^-1的电流密度下,1.0 mol·L^-1H₂SO₄溶液中的比电容值为307 F·g^-1,并具有良好的功率特性;此外,在10A·g^-1的大电流密度下充放电循环5000次后,NMCs的比电容值保持率为96.9%.     

Preparation and hydrogen storage properties of zeolite-templated carbon materials nanocast via chemical vapor deposition: effect of the zeolite template and nitrogen doping

Carbon materials have been prepared using zeolite 13X or zeolite Y as template and acetonitrile or ethylene as carbon source via chemical vapor deposition (CVD) at 550-1000 degrees C. Materials obtained from acetonitrile at 750-850 degrees C (zeolite 13X) or 750-900 degrees C (zeolite Y) have high surface area (1170-1920 m(2)/g), high pore volume (0.75-1.4 cm(3) g(-1)), and exhibit some structural ordering replicated from the zeolite templates. Templating with zeolite Y generally results in materials with higher surface area. High CVD temperature (> or =900 degrees C) results in low surface area materials that have significant proportions of graphitic carbon and no zeolite-type structural ordering. The nitrogen content of the samples derived from acetonitrile varies between 5 and 8 wt %. When ethylene is used as a carbon precursor, high surface area (800-1300 m(2)/g) materials are only obtained at lower CVD temperature (550-750 degrees C). The ethylene-derived carbons retain some zeolite-type pore channel ordering but also exhibit significant levels of graphitization even at low CVD temperature. In general, the carbon materials retain the particle morphology of the zeolite templates, with solid-core particles obtained at 750-850 degrees C while hollow shells are generated at higher CVD temperature (> or =900 degrees C). We observed hydrogen uptake of up to 4.5 wt % and 45 g H(2)/L (volumetric density) at -196 degrees C and 20 bar for the carbon materials. The hydrogen uptake was found to be dependent on surface area and was therefore influenced by the choice of zeolite template and carbon source. Zeolite Y-templated N-doped carbons had the highest hydrogen uptake capacity. Gravimetric and volumetric methods gave similar uptake capacity at 1 bar (i.e., 1.6 and 2.0 wt % for zeolite 13X and Y-templated N-doped carbons, respectively). Our findings show that zeolite-templated carbons are attractive for hydrogen storage and highlight the potential benefits of functionalization (nitrogen-doping).     

LaHZSM—5沸石的制备及其裂解性能研究

用常压和水热法制备了具有不同交换度的LaHZSM-5沸石,以XPS、IR、XRD及正十五烷裂解对其进行了表征。结果表明,水热法可获得较高交换度的LaHZSM-5沸石。La~(3+)交换的沸石较相同Si/Al比的HZSM-5沸石活性高,对气体的选择性降低,提高了C_(5～10)馏分的选择性。     

磷钨酸改性分子筛PW-β/MCM-41催化合成对甲氧基苯乙酮

以碱处理的β分子筛为硅铝源,十六烷基三甲基溴化铵为模板剂,制得β/MCM-41微-介孔复合分子筛(1),考察了NaOH溶液浓度和CTAB用量对1的影响。结果表明:用1.5 mol·L~(-1)NaOH溶液和10%CTAB溶液处理原料,1质量较好。以磷钨酸(PW)改性1制备了PW-β/MCM-41催化剂(2,PW负载量35%),其结构经FT-IR和XRD表征。以苯甲醚(AN)和乙酸酐(AA)合成对甲氧基苯乙酮(p-MOAP)为模板反应研究了2的催化性能,并考察了2的用量,物料比r[n(AA)∶n(AN)],反应温度和反应时间对p-MOAP收率的影响。结果表明:在最优条件(AN 0.05 mol,r=1.5,2 0.5 g,于105℃反应3.5 h)下,p-MOAP收率80.5%,选择性97.9%。     

不同载体负载Pd催化剂对甲酸的电催化氧化活性比较

应用Hummers法氧化合成氧化石墨(GO), 然后用化学一步还原法制得石墨烯（graphene）负载Pd催化剂. 用同样方法以多壁碳纳米管（MWCNTs）、单壁碳纳米管（SWCNTs）和Vulcan XC-72为载体制备了不同负载型的Pd催化剂. X射线衍射(XRD)、透射电镜(TEM)表征表明,在石墨烯载体上Pd纳米粒子粒径较小,且分布均匀. 电化学活性面积(ECSA)、循环伏安(CV)、计时电流(CA)和计时电位(CP)电化学测试显示, 与其它3种碳载体的Pd催化剂相比, 石墨烯负载Pd催化剂对甲酸电催化氧化的催化活性和稳定性最好.     

Electrical double-layer capacitor performance of nitrogen-doped ordered mesoporous carbon prepared by nanotemplating method

In this work, the electrical double-layer capacitive properties of nitrogen-doped ordered mesoporous carbons (N-OMCs) were investigated. Ordered mesoporous carbons (OMCs) with 3D body-centered Ia3d structure has been prepared by KIT-6 mesoporous silica as a hard template with aniline for N-OMC and sucrose for Su-OMC as a carbon precursor. Using the different carbon precursor, moderate amounts of nitrogen atoms could be doped to the OMC structures. The obtained materials were characterized by powder X-ray diffraction (XRD), nitrogen adsorption isotherms at 77 K, elemental analysis, and X-ray photoelectron spectroscopy (XPS). Prepared OMCs had mesopore properties such as a high surface area with narrow pore-size distribution. From cyclic voltammograms (CVs) test, N-OMC compared to Su-OMC exhibit higher capacitance and fast charge/discharge characteristics, which results from their pseudo-capacitive effect of incorporated nitrogen atoms. It was thought that N-OMC prepared by the nanotemplating method with KIT-6 and aniline were suitable electrode materials for electrical double-layer capacitors.     

Fe 含量对 FeAlPO-5 催化剂上甲烷还原 N2O 反应的影响

 采用水热法制备了一系列不同 Fe 含量的 FeAlPO-5 催化剂, 并将其用于 CH4 催化还原 N2O 反应. 结果表明, FeAlPO-5 催化剂在此反应中表现出较高的低温活性. N2 吸附、X 射线衍射和紫外可见光谱等表征结果表明, 水热法制备的 FeAlPO-5 催化剂具有典型的 AlPO-5 分子筛结构. Fe 含量对催化剂的活性及催化剂中 Fe 物种的分布有较大影响, 当 w(Fe) = 2.4% 时, 催化剂除含有可促使 CH4 低温还原 N2O 反应的孤立态的 Fe 物种和低聚态的 Fe 物种外, 还含有相当数量的可使 N2O 直接催化分解的纳米态的 Fe 物种.     

Photocatalytic synthesis of urea from in situ generated ammonia and carbon dioxide

TiO(2) and Fe-titanate (different wt%) supported on zeolite were prepared by sol-gel and solid-state dispersion methods. The photocatalysts prepared were characterized by X-ray diffraction, scanning electron microscopy and ultraviolet (UV)-visible diffuse reflectance spectroscopy techniques. Photocatalytic reduction of nitrate in water and isopropanol/oxalic acid as hole scavengers are investigated in a batch reactor under UV illumination. The yield of urea increased notably when the catalysts were supported on zeolite. The Fe-titanate supported catalyst promotes the charge separation that contributes to an increase in selective formation of urea. The product formation is because of the high adsorption of in situ generated CO(2) and NH(3) over shape-selective property of the zeolite in the composite photocatalyst. The maximum yield of urea is found to be 18 ppm while 1% isopropanol containing solution over 10 wt% Fe-titanate/HZSM-5 photocatalyst was used.     

Uranium and lead adsorption onto bentonite and zeolite modified with polyacrylamidoxime

Polyacrylonitrile (PAN) and bentonite (B)/zeolite (Z)-PAN composites were prepared by direct polymerization of acrylonitrile (AN) and AN adsorbed onto B and Z. PAN and the composites were subjected to amidoximation procedure to obtain polyacrylamidoxime (PAO), B-PAO and Z-PAO compositions. The structural features were evaluated by FT-IR, XRD and SEM analysis. The adsorption dependency of the materials on ion concentration, temperature and time were investigated for Pb²⁺ and UO₂ ²⁺. The adsorption capacities of B/Z-PAO composites were higher than those of pure PAO. The values of enthalpy and entropy changes were positive. The kinetics of the adsorption was well defined by the pseudo second order rate model. For the use of 1 M HCl as a regenerative effluent, the composites were reusable for five sequential treatments without any change in their structures whereas PAO completely gelled in the first use.     

Studies on the Surface Interaction Between MoO_3 and ZSM-11 Zeolite

A series of Mo-containing ZSM-11 zeolite catalysts has been prepared by calcining mixtures of MoO3 and ZSM-11 zeolite, and studied by using X-ray diffraction and infrared spectroscopy. It has been found that MoO3 can be well dispersed on ZSM-11 zeolite as a surface molybdenum species, and mostly within the zeolite cavities. With increasing the amount of dispersed MoO3, the zeolite framework is destroyed, and the crystallinity of the zeolite decreases. It seems that this perturbation is due to the strong interaction between dispersed MoO3 and zeolite framework.     

Preparation and characterization of templated porous carbons from sucrose by one-pot method and application as a CO2 adsorbent

The templated porous carbons were prepared from sucrose by one-pot method. In this method in which the pre-synthesis of the hard template is eliminated, the porous carbons were produced by organic-inorganic self-assembly of sucrose, tetraethyl ortosilicate (TEOS), Pluronic P123 and n-butanol in an acidic medium, and subsequent carbonization. The synthesis parameters such as sucrose amount, TEOS molar ratio and carbonization temperature were evaluated for describing their effects on the pore structures of the synthesized carbons. The prepared porous carbons were characterized by N₂ adsorption, thermogravimetric analysis (TGA), Raman spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) techniques. The carbon dioxide adsorption uptakes of the obtained porous carbons were determined at 1 bar and 273 K. The templated carbon obtained with the lowest TEOS molar ratio exhibited the highest BET surface area of 1289 m²/g and micropore volume of 0.467 cm³/g, and showed the highest CO₂ uptake of 2.28 mmol/g.