Polyaniline–13X zeolite composite‐supported platinum electrocatalysts for direct methanol fuel cell applications

We successfully synthesized 13X zeolite using a hydrothermal method. Then, composites of polyaniline (PANI) with 13X zeolite and PANI–13X with platinum were prepared by chemical oxidative polymerization and chemical reduction, respectively. Field emission scanning electron microscopy, X‐ray diffraction, Raman spectroscopy and Brunauer–Emmett–Teller techniques were used to characterize the PANI–Pt and PANI–Pt–13X composites. Further, the electrocatalytic activity towards methanol oxidation of the synthesized catalysts was explored using cyclic voltammetry in 1 mol L^?1 CH₃OH + 0.5 mol L^?1 H₂SO₄ solution. From the obtained results, PANI–Pt–13X shows superior performance compared to PANI–Pt towards methanol oxidation and electrical conductivity. Hence, the 13X zeolite‐incorporated PANI–Pt composite could be an efficient catalyst for direct methanol fuel cell applications. © 2019 Society of Chemical Industry     

低温等离子体协同CeO2/13X催化降解甲苯

低温等离子体协同催化剂技术（NTP-CAT）由于操作方便、能耗低等特点,特别适合用于工业非连续或连续消除低浓度VOCs过程。本研究发现NTP-CAT体系中CeO₂基催化剂更适合负载于13X载体以降解甲苯,并进一步考察CeO₂负载量对VOCs消除效果的影响。结果发现,NTP-CAT 体系中30% CeO₂/13X表现出最优性能,其可降解约85%的甲苯,CO₂产物选择性可达55%。表征结果也表明,Ce组分在30% CeO₂/13X表面仍可较好分散,而且表面的Ce³⁺物种含量最高。O₂-TPD实验结果证实表面Ce³⁺物种来源于Ce⁴⁺物种的等离子体处理。而且,表面Ce³⁺含量越高,有利于产生更多的氧物种,随后将与其周边13X吸附活化的甲苯反应。因此,甲苯降解在NTP-CAT体系中应存在分工协同机制。     

超声法制备Ce^4＋/13X分子筛的吸附脱硫性能

采用在离子交换过程中引入超声的方法制备了Ce4 /13X分子筛,考察了超声法对分子筛的制备及脱硫性能的影响,并考察了静态吸附条件对Ce4 /13X在低硫模型汽油(硫含量为23 mg/kg)中的脱硫性能影响。结果表明,超声法可显著缩短分子筛离子交换平衡的时间,提高离子交换度,且能有效地提高活性组分Ce在分子筛表面的含量,脱硫实验结果也显示吸附容量有明显的提高。常温常压,吸附时间为2.5 h,剂油质量比为0.0072的条件下,Ce4 /13X对噻吩的脱硫效果最好,吸附量为0.07653mmol/g,脱硫率可达到76.5%。Freundlich等温式能很好地关联噻吩在Ce4 /13X上的吸附平衡数据。450℃空气气氛中焙烧4 h的方法,可较好地再生Ce4 /13X。     

低温等离子体协同铜铈催化剂脱除甲苯

以挥发性有机化合物（VOCs）中的代表物质甲苯作为脱除对象,采用柠檬酸水热法制得铜铈催化剂,考察了低温等离子体协同不同摩尔比铜铈催化剂脱除甲苯的性能。研究发现铜铈复合型金属催化剂可以大幅度提升低温等离子体对甲苯的脱除效率,降低初始浓度、气体流速和升高电压可以提高甲苯脱除效率。同时利用N₂吸附-脱附（BET）、X射线衍射（XRD）、X射线光电子能谱（XPS）、程序升温还原（H₂-TPR）、红外光谱（FTIR）等手段对催化剂进行表征,发现催化剂活性组分分布较均匀,铜铈复合型金属催化剂表面氧空位、吸附态氧含量高于单金属氧化物催化剂,这有利于催化剂活性氧的释放。铜铈之间存在着协同作用,铜铈之间的氧化还原循环有利于甲苯的氧化。     

13X沸石分子筛对低浓度CO2动态吸附

目前对于吸附分离技术应用于高压、低浓度CO₂脱除的研究还较少,在进行相应吸附脱碳工艺设计时也缺少相关的参考数据。为探究13X沸石分子筛对低浓度CO₂的动态吸附性能,本文利用动态吸附实验的方法,探究不同条件下低浓度（摩尔分数3%）CO₂气体在13X分子筛上的动态吸附性能,得到不同压力、温度、气体流量、填料高度及分子筛规格（尺寸、形状）等因素影响下的13X分子筛对于CO₂气体的动态吸附规律及相应的性能指标参数。结果表明：随着吸附压力的升高,13X分子筛的CO₂吸附量增加但增量逐渐减小;降低吸附温度、减小气体流量和增加填料高度均有利于增强13X分子筛的动态CO₂吸附性能,提高吸附脱碳效果,其中温度及填料高度的变化对于CO₂吸附的影响程度最大;实验还发现小尺寸及条状13X分子筛的动态吸附脱碳性能优于其他规格,并根据其特定条件下的出口CO₂浓度为50mL/m³时的CO₂吸附量指标,给出吸附剂用量与液化天然气（LNG）脱碳工艺处理量的关系系数。     

分子筛对重金属废水吸附性能的实验研究

为验证分子筛对重金属废水的处理效果,以实际含锰废水为研究对象,采用13X分子筛,通过实验研究了吸附材料用量、吸附时间、搅拌转速和溶液pH对Ca²⁺、Mn²⁺、Mg²⁺吸附效果的影响。结果表明：吸附材料用量增加对Mn²⁺、Mg²⁺的吸附影响较大;随着吸附时间增长,各金属离子去除率增加;适当的转速有利于金属离子的吸附,但各金属离子对应的最佳转速各不相同;pH提高,能够促进分子筛对金属离子的吸附。13X分子筛对金属离子的吸附机理为离子交换吸附和表面吸附。研究表明,13X分子筛在处理低浓度含锰重金属废水方面表现出良好的应用前景。     

Adsorption of mercaptan from model gasoline on 13X loaded with Zn2+

Adsorption of mercaptan on 13X loaded with Zn²⁺ from model gasoline was studied at different concentration and temperatures. The results indicate that high temperature and low concentration favour the removal of mercaptan from the model gasoline. The adsorptive amount of the untreated adsorbents loaded with Zn²⁺ is less than the treated with heat obviously, but the adsorbed amount is not enhanced distinctly by the way of increasing the treating temperature. A pseudo‐first‐order mechanism has been proposed to describe the adsorption in the model gasoline system. The desulphurizing capability increases due to the Zn²⁺ impregnated. With the concentration of Zn²⁺ higher, the adsorptive amount for ethanethiol increases. Adsorption mechanism shows that it is a chemical adsorption. Two different methods of regeneration were investigated.     

13X分子筛去除废水中镍离子的性能研究

研究了13X分子筛用量、吸附时间、溶液pH值、初始镍离子浓度对废水中镍离子去除效果的影响.结果表明,在25℃、pH=5.9、13X分子筛质量浓度10 g/L、吸附时间30 min时,对初始质量浓度小于250 mg/L的镍离子去除率均可达到98%以上.13X分子筛重复使用5次,对废水中镍离子的去除率保持不变,再生性能良好...     

TEOS-化学液相沉积法改性ZSM-5催化剂上的高选择性甲苯择形歧化反应

Shape-selective catalysts for the disproportionation of toluene were prepared by the modification of the cylinder-shaped ZSM-5 zeolite extrudates with chemical liquid deposition with TEOS (tetraethyl orthosilicate).Various parameters for preparing catalysts were changed to investigate the suitable conditions.The resulting cata-lysts were tested in a pressured fixed bed reactor and characterized by SEM (scanning electron microscopy).The conversion of toluene and para-xylene selectivity were influenced remarkably by the n(SiO2)/n(Al2O3) ratio of ZSM-5 zeolite,the type and amount of deposition agent,acid and solvent used,and the time and cycle of deposition treatment.TEOS was proved to be a more efficient agent than the conventional polysiloxanes when the deposition amount was low.The catalyst prepared at the suitable conditions exhibited a high para-xylene selectivity of 91.1% with considerable high conversion of 25.6%.SEM analyses confirmed the formation of a layer of amorphous silica on the external surface of ZSM-5 zeolie crystals,which was responsible for the highly enhanced shape-selectivity.     

Conducting composites of poly(N‐vinylcarbazole), polypyrrole,and polyaniline with 13X‐zeolite

N‐vinylcarbazole (NVC) was polymerized by 13X zeolite alone in melt (65°C) or in toluene (110°C) and a poly(N‐vinylcarbazole) (PNVC)‐13X composite was isolated. Composites of polypyrrole (PPY) and polyaniline(PANI) with 13X zeolite were prepared via polymerization of the respective monomers in the presence of dispersion of 13X zeolite in water (CuCl₂ oxidant) and in CHCl₃ (FeCl₃ oxidant) at an ambient temperature. The composites were characterized by Fourier transform infrared analyses. Scanning electron microscopic analyses of various composites indicated the formation of lumpy aggregates of irregular sizes distinct from the morphology of unmodified 13X zeolite. X‐ray diffraction analysis revealed some typical differences between the various composites, depending upon the nature of the polymer incorporated. Thermogravimetric analyses revealed the stability order as: 13X‐zeolite > polymer‐13X‐zeolite > polymer. PNVC‐13X composite was essentially a nonconductor, while PPY‐13X and PANI‐13X composites showed direct current conductivity in the order of 10^?4 S/cm in either system. However, the conductivity of PNVC‐ 13X composite could be improved to 10^?5 and 10^?6 S/cm by loading PPY and PANI, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 913–921, 2006     

Analysis of dynamic CO2 capture over 13X zeolite monoliths in the presence of SOx,NOx and humidity

In this investigation, the CO₂ capture performances of zeolite 13X monoliths with 600 and 800 cells per square inch (cpsi) in the presence of SO₂/NO impurities under dry and humid conditions were evaluated and compared with that of 13X beads. Dynamic breakthrough tests demonstrated a drastic reduction in CO₂ capture capacity and deterioration of kinetics under dry-clean conditions, whereas, upon switching the feed from a clean gas to contaminated gas which contained SO₂ and NO, different adsorption performance was observed. Specifically, in dry-contaminated mode, the adsorbents retained their capture capacities with comparable kinetics to that of dry-clean feed conditions, however, in humid-contaminated mode, the adsorbents experienced improved CO₂ uptake and CO₂/N₂ selectivity, albeit at the expense of deteriorated kinetics. These findings indicate that the presence of SO₂ and NO contaminants, especially SO₂ contaminants, lead to dramatic changes in the adsorption performance of zeolite 13X monoliths, indicating the importance of evaluating adsorbent materials under realistic conditions.     

ZSM-5分子筛负载金属氧化物催化剂催化燃烧含丙烯腈废气的性能

采用等体积浸渍法将过渡金属Cu负载到ZSM-5分子筛上,并与其他金属(Fe、Co、Ag、Pd、Ce)共浸渍得到负载型催化剂,将其用于全组分丙烯腈废气的催化脱除过程。催化活性评价结果表明,丙烯腈在Cu/ZSM-5催化剂上320℃可以实现完全转化;掺杂质量分数2%Ce后,丙烯腈的完全转化温度降低到300℃,高选择生成N2的温度窗口也变宽,催化剂稳定性高。通过X射线衍射、氮气吸附-脱附、氢气-程序升温还原、氨气-程序升温脱附和X射线光电子能谱等对催化剂的物化性能进行表征,结果表明,催化剂催化氧化丙烯腈尾气的性能依赖于Cu^2+的还原能力、催化剂表面弱酸与中强酸含量以及表面Cu^2+丰度。     

A new catalytic process for high‐efficiency synthesis of p‐xylene by methylation of toluene with CH3Br

A new catalytic process for p‐xylene synthesis from the methylation of toluene with CH₃Br was proposed. CH₃Br was prepared from the catalytic bromination of natural gas (CH₄), by using H₂O + HBr + O₂ as mediator over supported Rh catalyst. The methylation conditions were investigated using HZSM‐5 or modified HZSM‐5 catalyst. Under optimal reaction conditions, p‐xylene selectivity is up to 93%, and p‐xylene yield is more than 21% at 673 k over the Si—P modified HZSM‐5 catalyst. Compared to the processes using MeOH or dimethyl carbonate (DMC) as methylation agent, this new process is very attractive in an economic standpoint since CH₄ is much cheaper than MeOH and DMC. In addition, the process has other advantages, such as mild reaction conditions, simple operation, high‐product yield, and so on. It is predicted that the process has good industrial potential for para‐xylene production. © 2012 American Institute of Chemical Engineers AIChE J, 59: 532–540, 2013     

Treatment of an industrial chemical waste‐water using a granular activated carbon adsorption‐microwave regeneration process

BACKGROUND: Industrial waste‐water is posing an ever‐greater environmental hazard. Recently, a process for purification combining activated carbon adsorption and microwave regeneration has drawn much attention. In this study, the effectiveness of this process for the treatment of industrial waste‐water from a chemical plant was tested. RESULTS: The effects of various factors including solution pH, granular activated carbon (GAC) dosage and contact time on the adsorption efficiency of organic compounds were studied. The regeneration of the exhausted GAC under microwave radiation was investigated, and the optimal conditions were: microwave power 400 W, radiation time 3 min for 10 g GAC. Under the optimal conditions the regenerated GAC recovered 97.6% of its original adsorption capacity. Repetitive uses of the GAC showed that it maintained a stable performance in the first few repetitions, but a decrease was observed after further repetitions. A GAC weight loss of about 10% at the sixth repetition was observed and a decrease in the surface area and increase in the surface basicity were observed for the regenerated GAC. Economic evaluation of the microwave regeneration process suggested that the total cost was about 24.3% of the GAC price at a pilot scale. CONCLUSIONS: A satisfactory regeneration of the chemical waste‐water exhausted GAC could be achieved under microwave radiation. The GAC adsorption‐microwave regeneration process was applicable for the treatment of this chemical waste‐water. Copyright © 2012 Society of Chemical Industry     

非热等离子体协同Mn-Ce/La/γ-Al2O3催化剂去除甲苯

采用自制线管式介质阻挡放电反应器,针对非热等离子体协同Mn-Ce/La/γ-Al₂O₃催化剂对低浓度甲苯的去除开展研究。研究中制备了Mn/γ-Al₂O₃、Mn-Ce/γ-Al₂O₃、Mn-La/γ-Al₂O₃催化剂,从甲苯去除率、产物O₃生成、CO_x选择性及其他副产物生成情况考察比较了空管放电、协同催化剂放电时催化降解甲苯性能,并对催化剂进行了BET、SEM、H₂-TPR和ICP-OES表征研究。结果表明：稀土助剂的加入有助于提高甲苯去除率及降低程度,且La催化性能优于Ce_.,当外加电压22 kV、气量6 L·min^-1、甲苯初始浓度600 mg·m^-3时,Mn-La/γ-Al₂O₃催化剂对甲苯去除率达到72.74%。H₂-TPR结果表明,稀土助剂的加入提高了催化剂低温活性及储氧能力,添加La的效果优于Ce。催化剂有助于抑制副产物O₃生成,提高CO₂和CO_x选择性。     

沸石吸附-SBR工艺对味精废水脱氮的试验研究

针对味精废水高氨氮的特点,提出并利用沸石吸附—SBR组合工艺进行味精废水脱氮。研究结果表明:沸石吸附—SBR组合工艺对味精废水中的氨氮具有较好的去除效果。沸石吸附氨氮可以减轻后续生化处理负荷,为最终出水氨氮能够达标排放创造条件。SBR进水阶段采用限制性曝气方式;运行工况为进水曝气8h、厌氧搅拌1h、后段曝气1h、沉淀lh、排水0.5h;硝化反应过程pH控制在8左右;硝化阶段、反硝化阶段溶解氧(DO)质量浓度分别控制在2.0mg/L和0.5mg/L左右。组合工艺出水NH3-N能满足《味精工业污染物排放标准》(GB19431—2004)中50mg/L的限值要求,组合工艺对NH3-N的平均去除率达96.7%。     

Adsorption and separation of CO2/N2 and CO2/CH4 by 13X zeolite

Accumulation of greenhouse gases in the atmosphere is responsible for increased global warming of our planet. The increasing concentration of carbon dioxide mainly from flue gas, automobile and landfill gas (LFG) emissions are major contributors to this problem. In this work, CO₂, CH₄ and N₂ adsorption was studied on Ceca 13X zeolite by determining pure and binary mixture isotherms using a constant volume method and a concentration pulse chromatographic technique at 40 and 100°C. The experimental data were then compared to the predicted binary behaviour by extended Langmuir model. Results showed that the extended Langmuir theoretical adsorption model can only be applied as an approximation to predict the experimental binary behaviour for the systems studied. Equilibrium phase diagrams were obtained from the experimental binary isotherms. For these systems, the integral thermodynamic consistency tests were also conducted. It was found that Ceca 13X exhibits large CO₂/CH₄ and CO₂/N₂ selectivity and could find application in landfill gas purification, CO₂ removal from natural gas and CO₂ removal from ambient air or flue gas streams. © 2011 Canadian Society for Chemical Engineering     

Kinetics of esterification of palmitic acid with isopropanol using p‐toluene sulfonic acid and zinc ethanoate supported over silica gel as catalysts

Kinetic data on the esterification of palmitic acid with isopropanol were obtained using homogeneous (para‐toluene sulfonic acid, p‐TSA) and heterogeneous (zinc ethanoate coated on silica gel, ZnA/SG) catalysts in a batch reactor. The ZnA/SG catalyst was prepared using a sol–gel technique. The esterification reaction was studied at different reaction temperatures (373–443 K), initial reactants molar ratio (1–5), catalyst loading (1–5 gcat dm^?3) and water concentration in feed (0–15 vol%). A power law rate equation was used for homogeneous kinetics analysis. The Langmuir Hinshelwood Hougen Watson (LHHW) model was used for heterogeneous kinetics. The kinetic parameters of both models were obtained using Polymath software. The reaction parameters were used to obtain simulated values of conversion for both catalytic systems. The simulated values were compared with the experimental values and were in good agreement. Copyright © 2004 Society of Chemical Industry