Influence of preparation methods on the physicochemical properties and catalytic performance of MnO_x-CeO_2 catalysts for NH_3-SCR at low temperature

This work examines the influence of preparation methods on the physicochemical properties and catalytic performance of MnOx‐CeO2 catalysts for selective catalytic reduction of NO by NH3 (NH3‐SCR) at low temperature. Five different methods, namely, mechanical mixing, impregnation,hydrothermal treatment, co‐precipitation, and a sol‐gel technique, were used to synthesizeMnOx‐CeO2 catalysts. The catalysts were characterized in detail, and an NH3‐SCR model reaction waschosen to evaluate the catalytic performance. The results showed that the preparation methodsaffected the catalytic performance in the order: hydrothermal treatment > sol‐gel > co‐precipitation> impregnation > mechanical mixing. This order correlated with the surface Ce3+ and Mn4+ content,oxygen vacancies and surface adsorbed oxygen species concentration, and the amount of acidic sitesand acidic strength. This trend is related to redox interactions between MnOx and CeO2. The catalystformed by a hydrothermal treatment exhibited excellent physicochemical properties, optimal catalyticperformance, and good H2O resistance in NH3‐SCR reaction. This was attributed to incorporationof Mnn+ into the CeO2 lattice to form a uniform ceria‐based solid solution (containing Mn‐O‐Cestructures). Strengthening of the electronic interactions between MnOx and CeO2, driven by thehigh‐temperature and high‐pressure conditions during the hydrothermal treatment also improved the catalyst characteristics. Thus, the hydrothermal treatment method is an efficient and environment‐friendly route to synthesizing low‐temperature denitrification (deNOx) catalysts.

Preparation of Ultrafine and High Dispersion Pd/C Catalyst and Its Electrocatalytic Performance for Formic Acid Oxidation

A carbon supported Pd（Pd/C） catalyst used as the anodic catalyst in the direct formic acid fuel cells（DFAFC） was prepared via the improved complex reduction method with sodium ethylenediamine tetracetate（EDTA） as stabilizer and complexing agent. This method is very simple. The average size of the Pd particles in the Pd/C catalyst prepared with the improved complex reduction method is as small as about 2.1 nm and the Pd particles in the Pd/C catalyst possess an excellent uniformity. The Pd/C catalyst shows a high electrocatalytic activity and stability for the formic acid oxidation.

Porous palladium phosphide nanotubes for formic acid electrooxidation

The development of an efficient catalyst for formic acid electrocatalytic oxidation reaction(FAEOR)is of great significance to accelerate the commercial application of direct formic acid fuel cells(DFAFC).Herein,palladium phosphide(PdxPy)porous nanotubes(PNTs)with different phosphide content(i.e.,Pd3P and Pd5P2)are prepared by combining the self-template reduction method of dimethylglyoxime-Pd(II)complex nanorods and succedent phosphating treatment.During the reduction process,the self-removal of the template and the continual inside-outside Ostwald ripening phenomenon are responsible for the generation of the one-dimensional hollow and porous architecture.On the basis of the unique synthetic procedure and structural advantages,Pd3P PNTs with optimized phos phide content show outstanding electroactivity and stability for FAEOR.Im portantly,the strong electronic effect between Pd and P promotes the direct pathway of FAEOR and inhibits the occurrence of the formic acid decomposition reaction,which effectively enhances the FAEOR electroactivity of Pd3P PNTs.In view of the facial synthesis,excellent electroactivity,high stability,and unordinary selectivity,Pd3P PNTs have the potential to be an efficient anode electrocatalyst for DFAFC.

An improved Hummers method to synthesize graphene oxide using much less concentrated sulfuric acid

The production of graphene oxide with less acid is beneficial to reduce the costs and lower the impact on the environment,but it is still a great challenge.In this work,a relatively simple,safe method for synthesizing graphene oxide with much less acid(decrease∼40%)is proposed.With assistance of the heat absorbed from environment and reaction system,the temperature of reaction system of low acid can be well controlled.More interestingly,the graphite can be completely oxidized into graphite oxide by using much less acid,with lowering the production of high-concentration aqueous waste acid(>1 mol/L,decrease∼40%).A series of characterizations show that the prepared graphene oxide has similar yield and functional groups compared with that of using the conventional method.This work provides a safe and environmentally friendly choice for the large-scale production of graphene oxide and its derivative materials.

Preparation of Spherical Tungsten Particles Assisted by Hydrothermal Method

We presented a strategy to prepare spherical tungsten powder by the combination of hydrothermal method and H2reduction process.In hydrothermal process,the micelle of tetraethylammonium bromide(TEAB)act as spherical templates for the deposition of tungsten oxide,whereas the excessive TEAB inhibit the formation of spherical tungsten oxide due to the dense molecular layer of TEAB on the tungsten oxide particles.Citric acid(CA)can control the formation rate and structure of the tungsten oxide when its concentration is more than 0.2 mol/L,because of its ability to coordinate with tungsten atoms.The synergistic effect of TEAB and CA facilitates the formation of spherical tungsten oxide with nanorod crown.After being treated by H_(2)at 600 and 650℃,the tungsten oxide particles are reduced to tungsten particles,which maintain the spherical structure of tungsten oxide and have porous structure.

Preparation and Catalytic Performance of Potassium Titanate Used as Soot Oxidation Catalyst

To prepare potassium titanate catalyst, a novel citrate acid complex-combustion method using CH3COOK and Ti（OC4H9）4 as raw materials was developed. The crystalline phase and surface morphology of K2Ti205 were investigated by X-ray diffraction （XRD）, field emission scanning electron microscope （FE-SEM） and transmission electron microscope （TEM）. The impact of some factors, such as the type of contact between K2Ti205 and soot, the content of water vapor and SO2 in exhaust, and the repeated use on catalytic activity of K2Ti205 were studied by temperature programmed reaction （TPR）. A comparison between the new method and the reported ones on catalytic activity of potassium titanate was investigated. The results showed that K2Ti205 had high catalytic activity and good stability.

基于过氧乙酸处理水中新污染物的研究进展

为了解决新污染物(emerging contaminants,ECs)在地表水和饮用水中威胁人类健康的问题,探讨了过氧乙酸(PAA)处理水中有机污染物的高级氧化技术(AOPs)。活化PAA有多种方式,包括光催化(紫外线UV)、超声活化(US)、过渡金属离子(Fe、Co、Mn和Cu)活化等。综述了基于PAA的AOPs去除水中有机污染物的相关研究成果,探讨了联用技术存在的问题与发展前景,为开发活化PAA技术处理水中新污染物提供了参考。

石灰铁盐法处理高砷废酸应用研究

选择工业具有代表性的高砷污酸,研究了石灰铁盐法控制性因素,如反应终点pH、Fe/As摩尔比、反应时间及氧化方式对除砷及固砷的影响。结合工业应用实际情况,在pH=1.2、石膏晶种比1∶1、反应时间2 h的条件下,优先产出合格石膏产品。再以H_(2)O_(2)为氧化剂,H_(2)O_(2)/As摩尔比1.5,反应终点pH=8,晶种比例1∶1,Fe/As摩尔比4.5,反应时间3 h进行除砷,除砷后液As浓度0.12 mg/L,小于标准值(0.5 mg/L),除砷率接近100%,除砷渣TCLP浸出毒性为2.25 mg/L,小于标准值(3 mg/L)。该工业应用工艺方法流程简单、操作方便、成本低廉,是一种可靠安全除砷固砷工艺。

复杂多金属银铜精矿湿法高效分离新工艺

采用硝硫酸浸铜-氧化焙烧脱硫-硝酸浸银、铅-水合肼还原银的实验流程,精矿中铜的回收采用硝硫混酸催化氧化浸出、浸液再经置换得到海绵铜;浸铜渣经氧化焙烧脱硫、碳酸钠转化后,用硝酸浸出其中的银、铅,再用氯化沉银分离银、铅,最终通过水合肼还原得到银粉,硫酸沉铅得到粗硫酸铅作为火法炼铅原料。精矿中的铁和少量的砷采用铁矾法净化脱除。结果表明:采用此工艺流程处理复杂多金属银铜精矿,银直收率达到90%以上,铜直收率达到93%以上,铅直收率达到92%以上。

化学氧化法处理含甲酸废水实验研究

含甲酸废水直接排放不仅会造成严重的环境污染,还会造成一定的资源浪费。因此,以某化工企业含甲酸废水为研究对象,以废水中COD的去除率为评价指标,采用化学氧化法对其进行了处理,并重点评价了氧化剂类型、氧化剂加量、废水p H值、废水矿化度、氧化反应时间和氧化反应温度对含甲酸废水处理效果的影响。结果表明:在相同的实验条件下,6种不同类型的氧化剂中复合氧化剂FO-2的COD去除率最大,对目标含甲酸废水的处理效果最好。氧化剂的加量越大,氧化反应时间越长,COD去除率相对就越大;废水矿化度越高,COD去除率相对就越小;酸性至中性条件更有利于COD去除率的提高;氧化反应温度对COD去除率的影响相对较小。当复合氧化剂FO-2的加量为30 mg·L^(-1)、废水p H值为7、废水矿化度为2 000 mg·L^(-1)、氧化反应时间为50 min、氧化反应温度为30℃时,含甲酸废水经过化学氧化处理后的COD去除率可以达到90.4%。研究结果表明,化学氧化法能够满足低浓度甲酸废水处理的需求。

浅谈废酸再生装置的NO_(x)

分析了废酸裂解装置中NO_(x)的来源以及NO_(x)对装置运行的影响,介绍了预脱除法、选择性催化还原法和选择性非催化还原法、两段焚烧法、臭氧法,以及低氮燃烧技术等常用的控制和脱除NO_(x)的方法。

焙烧工艺参数对酸再生系统和氧化铁粉的影响

介绍了喷雾焙烧法酸再生的工艺流程,通过控制变量法研究了焙烧工艺参数,如焙烧炉温度、负压、氧含量、酸枪压力,对酸再生系统和氧化铁粉的影响,讨论并分析了这几个工艺参数影响酸再生系统和氧化铁粉的原因,在此基础上提出了工艺参数优化的建议。

乙二醛阳极氧化制乙醛酸过程的化学分析方法

乙二醛阳极氧化制乙醛酸的电解液可用简便的化学分析法测定 ,其中草酸的定量可用钙盐沉淀后用高锰酸钾法测定 ;乙二醛的定量用坎尼查罗反应后用标准酸测定 ;醛总量用亚硫酸钠法测定 ,乙醛酸的定量用醛总量减乙二醛的量。

二氧化钛基固体超强酸的结构及其光催化氧化性能

采用 溶 胶凝 胶 法 制 备 了 多 孔 性 、大 比 表 面 积 的 Ｓ Ｏ２ －４ ／ Ｔｉ Ｏ２ 固 体 超 强 酸 催 化 剂， 运 用 Ｘ Ｒ Ｄ ， Ｂ Ｅ Ｔ 比表面 积测定 ， Ｘ Ｐ Ｓ 和 Ｕ Ｖ Ｖｉｓ 反 射光 谱等 技 术对 该 催化 剂 的结 构、表 面状 态 以 及半导体特 性进行了 表征，并 通过 Ｃ Ｈ３ Ｂｒ ， Ｃ６ Ｈ６ 和 Ｃ２ Ｈ４ 等典型有 机物的 气相光催 化氧 化反 应，考 察了 Ｓ Ｏ２ －４ ／ Ｔｉ Ｏ２ 催化剂 的光 催 化 反 应 性 能． 结 果 表 明， Ｓ Ｏ２ －４ ／ Ｔｉ Ｏ２ 催 化 剂 具 有 较 高 的 结 构 稳 定 性， Ｔｉ Ｏ２ 的超强 酸化有效 地抑制 了晶相转 变、晶粒 度增加和 比表 面积 下降． 与 Ｔｉ Ｏ２ 相 比， Ｓ Ｏ２ －４ ／ Ｔｉ Ｏ２的吸收 边蓝移 及禁带宽 度增加， 产生了较 大的氧 化还原势 ，导致光 催化效率 提高．

测定铬铁矿中氧化亚铁的溶样方法研究

证明了经沸腾硫酸（-330℃）湿烧法预处理的铬铁矿的物质组成发生相变、反应产物硫酸铬生成、化学活性增强以及磷酸（硫-磷混合酸）对其溶解反应明显变易等,从而改进了测定铬铁矿中氧化亚铁的溶样方法。试样首先与钒（Ⅴ）-钒（Ⅳ）溶液和硫酸混合,于2 000 W电炉上加热至冒浓三氧化硫烟,并至腾空1-3 min,然后加入缩合磷酸,再加热至冒浓烟,并至腾空3-5 min。所得试液适当冷却、稀释,用硫酸亚铁铵标准溶液滴定剩余的钒（Ⅴ）,通过空白实验计算氧化亚铁的含量。同时对硫酸湿烧法的作用及其反应机理也进行了探讨。方法用于铬铁矿中氧化亚铁的测定,经标样以及生产样品分析数据对比,结果均较满意。

石墨坩埚浸渍法抗氧化试验研究

研究了浸渍剂组成及浸渍工艺方法对石墨坩埚试样抗氧化性能的影响及作用机理。结果表明 :试样浸渍Al/P比值为 1/2的酸式磷酸铝、控制工艺过程中浸渍剂和试样的温度在 90℃左右 ,石墨坩埚试样浸渍处理后可获得较理想的抗氧化性能。浸渍酸式磷酸铝试样在 10 0 0℃以下的抗氧化是 [Al(PO3) 3] n对试样的包覆及填充作用 ,在 10 0 0℃以上则是Al(PO3) 3分解后的AlPO4 发挥作用。

Mn-Mo/SiO_2催化剂的制备及其催化柴油氧化脱硫

采用溶胶-凝胶法制备锰离子改性的Si O2负载的磷钼酸催化剂,并采用傅里叶红外光谱(FT-IR)、X射线衍射(XRD)和扫描电镜(SEM)等对催化剂进行表征。考察了催化剂用量、过氧化氢用量、反应温度和反应时间等对模型油(苯并噻吩和二苯并噻吩)和直馏柴油氧化脱硫的影响。结果表明:锰离子改性后,催化剂仍然保持了磷钼酸的Keggin型结构,其活性中心的分散度和比表面积均增加;不同反应条件对模型油的氧化脱硫均有影响,且二苯并噻吩(DBT)较苯并噻吩(BT)更易脱除。正交试验结果显示,各因素对柴油脱硫率的影响由大到小依次为反应时间>催化剂用量>过氧化氢用量>反应温度。在催化剂0.15 g,过氧化氢0.25 mL和反应温度70℃的条件下,反应时间4 h后,直馏柴油的脱硫率达90.3%,油品回收率不低于98%。

纳米氧化镁的制备及其紫外屏蔽性能

以苹果酸和硝酸镁为原料,采用溶胶-凝胶法（sol-gel）制备了氧化镁纳米晶。根据制备条件的不同,粒径可在7-20 nm之间。采用傅立叶红外光谱、热分析、X射线衍射、透射电子显微镜测试技术对凝胶的组成和热分解过程,凝胶和样品的物相组成以及样品的形貌、粒径大小、分布情况进行了分析;考察了原料配比、煅烧温度和时间、溶液初始pH值、乙醇用量对样品形貌和粒径的影响。结果表明,硝酸镁与苹果酸的摩尔比为1∶1.5,煅烧温度在500-700℃,煅烧时间为3 h,溶液初始pH值在3-7,V（乙醇）∶V（水）=1∶4时为最佳反应条件;紫外可见光谱（UV-V is）分析表明,纳米氧化镁的紫外屏蔽性能优于普通的氧化镁粉体。

ZnO的制备及其光催化性能

分别采用草酸沉淀法和柠檬酸络合法制备了纤锌矿型ZnO,通过X射线粉末衍射仪、扫描电子显微镜和透射电子显微镜对ZnO的结构和形貌进行了表征,并研究了所制备的ZnO对溶液中甲基橙的光催化降解性能。实验结果表明:草酸沉淀法制备的ZnO为小颗粒堆积而成的空心类柱状体,柠檬酸络合法制备的ZnO为小球形颗粒;草酸沉淀法制备的ZnO比柠檬酸络合法制备的ZnO有更好的光催化性能,光照反应30m in,草酸沉淀法制备的ZnO的甲基橙降解率达94.36%,柠檬酸络合法制备的ZnO的甲基橙降解率达81.75%。

电生成强氧化剂处理染料废水试验研究

本文研究了用电化学方法生成的强氧化剂H2O2和HClO处理酸性铬兰K染料废水。在电解过程中向阴极表面通纯氧,氧在阴极上还原可生成H2O2,以NaCl作为电解质,Clˉ在阳极上还原为Cl2,Cl2进一步转化为HClO,H2O2和HClO都是强氧化剂,都可氧化降解染料分子。电解废水30.0min,褪色率和CODcr去除率分别为90.5%和76.7%,电解废水50.0min, 褪色率和CODcr去除率分别为100.0%和83.1%。