Mn-Fe/ACF催化剂低温选择性催化还原NO

以自制的芳纶滤料基活性炭纤维(ACF)为载体,采用等体积浸渍法制备了一系列1.2%Mn-Fe/ACF催化剂,并将其应用于低温SCR脱硝。采用BET、XRD、FESEM及EDS对催化剂的微观结构进行表征。活性实验结果表明,适量Fe元素的加入有利于提高催化剂的活性,其中1.2%Mn(0.75)-Fe/ACF催化剂在空速高达56 000 h-1、温度为200℃的条件下的脱硝效率可达92%。BET、XRD和SEM结果显示高的比表面积和载体表面金属氧化物的均匀分布有利于提升催化剂的催化活性。     

SO2促进的碳纳米管负载V2O5催化剂用于NH3选择性还原NO

采用透射电镜(TEM)、X射线光电子能谱(XPS)、红外光谱(FT-IR)、SCR反应和程序升温脱附(TPD)等手段研究了碳纳米管(CNTs)担载的五氧化二钒(V2O5/CNTs)催化剂的形貌、表面形态以及SO2对选择催化NO还原活性的影响.结果表明,SO2对V2O5/CNTs催化剂的催化活性具有明显的促进作用,其促进作用源于SO2在催化剂表面的吸附.吸附的SO2主要位于碳表面而非钒表面,而且这种促进作用与V2O5和碳表面之间协同作用有关.     

Low-temperature selective catalytic reduction of NO with CO over Nix-MOF-5

Journal of Materials Science - The catalyst with a high NO conversion rate and good sulfur resistance is the key to CO-selective catalytic reduction (CO-SCR). Ni doping MOF-5 was synthesized...     

Co-Mo系耐硫阳极催化剂的制备与表征

采用溶胶一凝胶法制备了Co-Mo二元硫化物阳极催化剂.通过TG、SEM对催化荆进行表征,测定催化剂在1000℃以下时的电导率;通过比较催化剂在反应前后的红外光谱图,评价催化剂的耐硫性能.结果表明:Co-Mo阳极催化剂具较好的热稳定性,较大的孔隙率和电导率,以及优越的耐硫性能,满足固体氧化物燃料电池阳极催化剂的要求,是一种新型的耐硫阳极材料.     

Biochar supported manganese based catalyst for low-temperature selective catalytic reduction of nitric oxide

Clean Technologies and Environmental Policy - This research work aims to study the performance of biochar-supported manganese-based catalysts for conversion of NOx in the selective catalytic...     

SCR烟气脱硝催化剂V_2O_5-WO_3/TiO_2性能研究

通过浸渍法制备了V2O5-WO3/TiO2催化剂,考察催化剂在SCR反应中的脱硝性能.结果表明,WO3的引入扩宽了催化剂的反应窗口,随着WO3含量增加,脱硝率略有上升,特别是在高温阶段.当WO3含量为8%时,催化剂具有最佳效果,在250~400℃范围内,NO脱除率都能达到95%以上,450℃时,脱硝率仍能达到89.19%.此外,进一步考察了空速值、氧浓度、氨氮比、NO初始浓度等不同条件下对催化剂活性的影响.     

选择性混合型燃料电池膜电极的制备及性能研究

以Pt-Ru/C和Pt/C分别为阴极、阳极催化剂,以多孔聚丙烯薄膜浸渍Nafion溶液作为CMRFC的固体电解质膜(MEA),自制多孔选择性膜电极,并组装了单电池以及测试系统。以甲醇和氧气共同输送作为混合燃料,研究了阴极PTFE与Nafion含量及其分布对单电池的极化与功率特性以及单电池在放电运转过程中阴极氧化剂种类对单电池性能的影响,并考察了单电池的放电性能。研究表明,气体扩散层中微孔碳层中PTFE的质量含量为40%,催化层PTFE为30%时,在燃料供给条件为18.9mL.min-1,0.5mol.L-1的甲醇溶液+0.21 min-1O2时,MEA的电性能最好,稳定放电时最大功率可达0.55mW.cm-2(0.125V时)。     

高活性丙烯腈水合铜基催化剂的制备与表征

在丙烯腈水合制备丙烯酰胺的反应中,采用共沉淀方法制备催化剂,通过反应考察了催化剂的催化活性,并用XRD和TPR对水合用铜基催化剂做了物相表征.结果表明,采用碱单流加料,Cu/Al为40/60时,反应转化率最高可达90.9%,选择性最高可达99.1%.XRD和TPR测定表明,催化剂的催化活性与孔雀石和水滑石晶相的粒度、两者的比例密切相关.两者粒度小,比例恰当,催化剂活性高.     

PEMFC用抗溺水性功能化Pt/C催化剂的制备及表征

催化剂的碳载体腐蚀是Pt/C催化剂催化性能下降的重要原因,并且亲水性的催化剂增加了质子交换膜燃料电池氧电极发生水淹的风险。利用过氧化氢对XC-72碳进行氧化预处理,负载Pt后,进一步用水合肼对Pt/C催化剂还原,制备耐蚀性和抗溺水性的Pt/C催化剂。对红外光谱吸收峰进行比较可知,经双氧水处理后,XC-72碳表面的含氧官能团数量增加,其接触角小于未经处理的XC-72碳;进一步用水合肼还原氧化后的XC-72碳,接触角较氧化的XC-72碳增大22.4°,抗溺水性增强。由比表面积测定可知,双氧水处理XC-72碳,比表面积下降,但中孔比例增加,有利于Pt的负载。水合肼还原后的Pt/C催化剂较还原之前的Pt/C催化剂抗溺水性增强,接触角增大6.2°。经2000周次循环伏安扫描,水合肼还原后的Pt/C催化剂电化学比表面损失减小,耐久性提高。     

Preparation and characterization of Pt-polypyrrole nanocomposite for electrochemical reduction of oxygen

An easy and simple method of one-step reaction was employed to synthesize the platinum-adsorbed polypyrrole nanocomposite (Pt-PPy). The prepared nanocomposite materials were characterized using UV–vis absorption spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and cyclic voltammetry. Polypyrrole within nanocomposite could crosslink to improve its stability on the Au substrates. O₂ reduction was performed at Au electrodes modified Pt-PPy in O₂-saturated 0.5 M H₂SO₄ solution. The results clearly show that modification of Pt-PPy nanocomposite results in the enhancement of the electrocatalytic reduction of oxygen. The nanocomposite may provide a novel electrode material for application in fuel cells and oxygen sensors.     

Preparation and characterization of molecularly imprinted polymers for the selective separation of 2,4-dichlorophenoxyacetic acid

As a method of preparing ligand-selective cavities in a synthetic polymer matrix, molecular imprinting technique has been attracting significant interest from a large number of areas in chemistry and analytical sciences. In this study, molecularly imprinted polymers (MIPs) were prepared with styrene, 4-vinylpyridine (4-VPy), and divinylbenzene (DVB) for the separation of hazardous 2,4-dichlorophenoxyacetic acid (2,4-D), and the selectivity of MIPs as adsorbed 2,4-D and structurally similar materials was evaluated. The template was removed through the swelling process of toluene/ethanol, and the removal ratio was about 95–99%, respectively. MIPs synthesized in this study had good adsorption selectivity in the presence of other materials, although there was a difference of adsorption quantities (uptake) in the functional monomer (4-VPy contents) and the cross-linker (DVB contents). The results exhibit that the selectivity of MIPs was improved significantly by controlling the cross-linker. We expect that molecular imprinting technique will serve as a novel method for selective separation of specific materials in various fields, especially in the fields of environment and pharmaceutics.     

不同锰含量纳米MnO2-Fe2O3-CeO2/Al2O3的制备、表征及其催化还原NO/NO_2性能

减少发动机冷启动极低温度下排气中的NO_x对于生态环境与人类健康至关重要,MnO₂在低温区间对NO_x具有较高催化活性,是一种极具发展前景的纳米催化剂。通过超声波辅助共沉淀法制备不同锰含量MnO₂-Fe₂O₃-CeO₂/Al₂O₃纳米催化材料,探讨表面结构特性与其脱硝活性的内在联系。研究发现:锰含量为15%(质量分数)时具有最大比表面积与最小晶粒,活性物质分布最为均匀,金属氧化物结晶度得到抑制,Mn,Fe和Ce呈现较佳共存态,能够促进化学吸附氧的富集,并通过提高NO催化氧化成NO₂来提高快速SCR反应速率,NO₂转化率在50℃时即达到了88.5%。在改善催化材料构效关系、提高NO预氧化和快速SCR反应性能方面,优化锰含量是一种极其有效的方法。     

化学气相沉积制备V2O5-WO3/TiO2催化剂及表征

以蜂窝堇青石为基体,采用化学气相沉积技术结合浸渍工艺制备出V2O5-WO3/TiO2脱硝催化剂,通过SEM、BET、XRD和EDS完成载体以及催化剂微观结构和成分表征,并利用活性评价装置测试了催化剂NO脱出率。试验结果表明,化学气相沉积技术制备的载体表面为锐钛矿型TiO2,其颗粒聚集成团块状,BET为62.73m2/g,平均孔径为9.8nm。制备的V2O5-WO3/TiO2催化剂孔结构规律与TiO2载体相似,V2O5在TiO2载体上无定形态单层分散,微量V2O5在微区长大成针状,宽度100nm;在350℃、4000h-1、n(NH3)/n(NO)=1时,催化剂NO脱出率ηNO达到96.7%。     

Preparation and characterization of chitosan hydrogel membrane for the permeation of 5-Fluorouracil

Four kinds of chitosan membranes, (Ch, C-G, C-N, and C-GN), were prepared in this study. Ch system of chitosan membranes were prepared by solution casting method without any treatment. C-G system of chitosan membranes were prepared by solution casting method with adding glutaraldehyde as crosslinking agent. C-N system of chitosan membranes were prepared by solution casting method with the treatment of NaOH solution. C-GN system of chitosan membranes were crosslinked with glutaraldehyde and treated with 1 M NaOH solution. Infrared spectroscopy and differential scanning calorimetry (DSC) were conducted to characterize the structure and thermal properties of chitosan membrane. To evaluate the usage of chitosan for the carrier of drug, water content and degradation of the chitosan membrane were determined. It was found that the values of equilibrated water content in chitosan membranes increased with the chitosan content in the stock chitosan solution. The assessment of 5-FU permeability through the chitosan membranes was determined. The linear relationship between the permeability of 5-FU through the membrane and the wt.% of chitosan content in stock chitosan solution was found. Both values of intercept and slope were determined. The value of intercept means that the permeability of 5-FU through the chitosan membrane, which is assumed to be prepared from stock chitosan solution containing infinite dilute chitosan content. The value of slope indicates that the effect of the treatment method on the permeability of 5-FU through the chitosan membrane. From the evaluation of normalized flux, diffusivity and saturation concentration of 5-FU in various chitosan membrane, it was found that more number of 5-FU molecules were trapped in the chitosan membrane of C-GN system than that in C-N system and resulted in the decrease of diffusivity of 5-FU molecules through the chitosan membrane.     

ZSM—5沸石膜的合成与表征

叙述了沸石膜的发展与应用,综述了 Ｚ Ｓ Ｍ － ５ 沸石膜的合成、修饰与表征方法．制备膜最常用的方法为水热法在载体上直接就地合成．气相化学沉积法（ Ｃ Ｖ Ｄ） 、溶胶－ 凝胶法（ｓｏｌ － ｇｅｌ） 以及合成后积炭等方法被用来对膜的缺陷进行修饰．膜的表征手段为 Ｘ Ｒ Ｄ、 Ｓ Ｅ Ｍ、气体渗透等