废钯炭催化剂分析方法的研究

对废钯炭催化剂分析方法进行了研究,将废钯炭催化剂用高温煅烧的方法除去其中的活性炭并收集燃烧气体中的含钯微粒,采用甲酸代替碱性甲醛溶液或氨性水合肼作还原剂,过氧化氢-盐酸混合溶液代替王水作溶剂,提出了一种方法简单、浸出效果好、易操作的废钯炭催化剂分析钯的方法。试验表明,本方法适用于实际分析检测应用。     

A new environmental chamber for evaluation of gas-phase chemical mechanisms and secondary aerosol formation

A new state-of-the-art indoor environmental chamber facility for the study of atmospheric processes leading to the formation of ozone and secondary organic aerosol (SOA) has been constructed and characterized. The chamber is designed for atmospheric chemical mechanism evaluation at low reactant concentrations under well-controlled environmental conditions. It consists of two collapsible 90 m³ FEP Teflon film reactors on pressure-controlled moveable frameworks inside a temperature-controlled enclosure flushed with purified air. Solar radiation is simulated with either a 200 kW Argon arc lamp or multiple blacklamps. Results of initial characterization experiments, all carried out at 300–305 K under dry conditions, concerning NO_x and formaldehyde offgasing, radical sources, particle loss rates, and background PM formation are described. Results of initial single organic–NO_x and simplified ambient surrogate–NO_x experiments to demonstrate the utility of the facility for mechanism evaluation under low NO_x conditions are summarized and compared with the predictions of the SAPRC-99 chemical mechanism. Overall, the results of the initial characterization and evaluation indicate that this new environmental chamber can provide high quality mechanism evaluation data for experiments with NO_x levels as low as 2 ppb, though the results indicate some problems with the gas-phase mechanism that need further study. Initial evaluation experiments for SOA formation, also carried out under dry conditions, indicate that the chamber can provide high quality secondary aerosol formation data at relatively low hydrocarbon concentrations.     

基于文献计量的汽车尾气净化产业专利技术态势分析

汽车尾气是空气污染的主要来源之一,为防治大气污染,我国连续出台了多项政策和标准,严格控制机动车尾气污染,汽车尾气处理产业也迎来了快速发展机遇。对汽车尾气净化技术相关的专利进行检索,分析汽车尾气净化相关产业技术的发展态势,结果表明,汽车尾气净化技术重点涉及催化处理技术、过滤净化技术、反应装置与处理系统、监测装置等。日本在本领域的专利申请占绝对优势,但近年来专利申请量有所下降。核心专利技术主要集中在以丰田、巴斯夫（Engelhard）、福特等企业为代表的日本、美国和德国的专利权人手中。我国虽然在专利总量上位居全球第3,近年来,年度专利申请量赶超日本,跃居全球首位,但是专利质量和企业竞争力仍有待提高。未来我国应加大高效催化剂及其组合技术的研发,降低尾气净化产品的成本,提高批量生产能力和产品质量,提升企业竞争力。     

γ-Al2O3负载Mn基催化剂低温催化臭氧氧化NO

利用等体积浸渍法制备γ-Al2O3负载Mn基催化剂,考察了掺杂元素种类,掺杂元素与Mn元素摩尔比以及煅烧温度对NO低温（100 ℃）催化氧化活性的影响,并对催化剂在有SO2或H2O的烟气中的稳定性进行了探究。结果表明,掺杂元素为Ce,Ce/Mn=0.4,煅烧温度为500 ℃条件下制备的催化剂NO催化活性最佳,在NO体积浓度为500×10-6,臭氧浓度为20.9 mg·L-1,n(O3)/n(NO)=0.2,反应温度为100 ℃,模拟烟气总流量为1.0 L·min-1,模拟烟气相对湿度为4%的条件下,NO的转化率最高可达70%。此外,还对催化剂在不同条件下的稳定性和活性恢复情况进行了探究。实验最终实现了在低O3浓度条件下达到较高NO转化率的目的,为烟气脱硝提供了一种具有应用潜力的新技术。     

硅镁胶的合成及对有机酸的吸附

采用水热法以硅酸钠和氯化镁为原料合成新型硅镁胶。通过改变硅镁胶投加量,吸附时间,吸附温度等条件,得到最佳实验条件。测定了25℃时硅镁胶自水溶液中吸附甲酸、乙酸、丙酸、丁二酸和乳酸的等温线,等温线为S型、C型、L型和H型;测定了25℃时硅镁胶自甲酸甲酯溶液中吸附正辛酸、正己酸和油酸的等温线,等温线为S型和C型。通过计算,Freundlich吸附等温模型能够较好地描述系列有机酸硅镁胶上的吸附过程。硅镁胶材料对有机酸有较好地吸附处理效果,吸附量维持在2 000 mg·g-1左右,对生物柴油中的主要有机酸成分的油酸的吸附量达到3 500 mg·g-1,为硅镁胶应用于生物柴油中的脂肪酸的精制处理提供可行性理论支撑。     

CuxFe1-x@γ-Al2O3催化剂湿式氧化陶瓷印花废水的性能及表征

采用常温浸渍法制备催化剂CuxFe1-x@γ-Al2O3,并用于陶瓷印花废水的催化湿式氧化处理,考察组分构成对催化剂CuxFe1-x@γ-Al2O3活性和稳定性的影响。结果表明：在4种样品Cu0.5Fe0.5@γ-Al2O3,Cu@γ-Al2O3,Fe@γ-Al2O3和γ-Al2O3中,Cu0.5Fe0.5@γ-Al2O3的催化活性和稳定性最高。催化剂Cu0.5Fe0.5@γ-Al2O3中的Fe促进Cu进入γ-Al2O3载体内部并形成稳定的固溶体Al2CuO4,故此催化剂的硬度和稳定性最高;此催化剂应用前后的SEM图无明显的形貌变化,XRD谱图无明显的物相变化,证实了其稳定性的存在。在优化的操作条件下,催化剂Cu0.5Fe0.5@γ-Al2O3催化湿式氧化陶瓷印花废水的COD及色度分别为280 mg·L-1、20倍,达到《污水综合排放标准》（GB 8978-1996）中染料类废水的三级排放标准。     

2,4-dichlorophenoxyacetic acid (2,4-D) micropollutant herbicide removing from water using granular and powdered activated carbons: a comparison applied for water treatment and health safety

Abstract

Activated carbons are well-known porous materials as an effective adsorbent used for the removal of emerging contaminants, such as herbicides, which are increasingly present in water bodies. Most water treatment plants, specially in Brazil, are unable to completely remove such contaminants by the conventional process and advanced treatment using activated carbons is required. The aim of this paper was to verify the influence of the activated carbons granulometry and specific surface area on the 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide removal efficiency using distilled-deionized water and filtered water collected from a conventional Water Treatment Plant. Commercial activated carbons samples used in this work were obtained from two different manufacturers. Activated carbons were analyzed by the specific surface area, pore size and volume distribution, nuclear magnetic resonance, infrared and x-ray spectroscopy, moisture, volatile matter and ash contents. Batch adsorption isotherms experiments were used and performed by Langmuir and Freundlich models. Granular and powdered activated carbons removed over 99% of 2,4-D in distilled water and near to 99% using filtered water. The activated carbons evaluated in this work presented high performance and played a key role in water treatment by removing 2,4-D herbicide, ensuring the protection of human health and the ecosystem.     

DSB+CPB复合改性膨润土对磷酸盐的吸附

为研究两性-阳离子表面活性剂复合改性膨润土的吸附除磷性能及其机理,采用不同比例两性表面活性剂——十二烷基二甲基磺丙基甜菜碱(DSB)和阳离子表面活性剂溴代十六烷基吡啶(CPB)对膨润土进行了有机复合改性,制得DSB+CPB复合改性膨润土,利用X射线衍射分析(XRD)、傅里叶红外分析(FT-IR)、扫描电子显微镜(SEM)、接触角(CA)以及热重分析(TGA)等手段对膨润土土样进行了表征,并用吸附等温模型和动力学方程拟合其吸附过程,探讨了改性比例、pH和温度等因素对吸附的影响。结果表明：DSB改性能提高膨润土对磷酸盐的吸附能力,当加入CPB复合改性后,可进一步促进DSB改性膨润土对磷酸盐的吸附能力,且吸附能力均随改性比例的增大而增强;对于0.5 DSB和1.0 DSB的改性膨润土,其与CPB最佳复合比例均为DSB+1.5 CPB,最大吸附量分别为原土的7.81倍和8.19倍;改性膨润土对磷酸盐的吸附均符合Langmuir等温模型和伪二级吸附动力学方程,其吸附能力随pH的升高而降低,且吸附为物理和化学吸附同时存在的自发吸热熵增过程。上述研究结果可为两性-阳离子表面活性剂复合改性膨润土吸附除磷提供参考。     

Ce-TiO2催化剂在含SO2气氛下的NH3-SCR中毒机理及其Co3O4改性性能

通过对Ce-TiO₂催化剂在含硫气氛下、不同温度的NH₃-SCR活性演变,结合含硫组分的定量分析、原位红外分析,研究了Ce-TiO₂催化剂在不同温度的SO₂中毒机理。结果表明,在180 ℃下,Ce-TiO₂脱硝活性对硫酸铈的生成极为敏感,0.1 mmol·g⁻¹的硫酸铈生成导致脱硝活性从50.7%降至18.5%,随后硫酸铈持续沉积,低温脱硝活性缓慢下降;在240 ℃下,Ce-TiO₂脱硝活性对硫酸铈的生成敏感性较低,脱硝活性随时间缓慢下降,0.18 mmol·g⁻¹的硫酸铈生成导致脱硝活性从100%降至53.8%,随后硫酸铈持续生成。Co改性活性结果表明：在180 ℃时,脱硝活性从50.7%提升至94.2%,且180 ℃和240 ℃抗硫性能均有所提升。进一步的表征测试表明：Co的掺杂能提升Ce-TiO₂催化剂的氧化还原性能,并抑制SO₂在催化剂表面的吸附,提升催化剂的抗硫性能。原位红外测试结果表明：硫酸化后的Ce-Co-TiO₂催化剂仍能维持了E-R、L-H脱硝反应路径的进行,保证了一定的低温脱硝活性。本研究探索了SCR催化剂的中毒机制,可为其改性与活性提升提供参考。     

涂覆式蜂窝状钒钨钛催化剂的SCR及抗中毒性能

为制备性能优异的涂覆式蜂窝状SCR催化剂用于高效去除NO_x,采用正交实验探究添加剂对催化剂的涂覆效果及SCR性能影响。结果表明,当PVA和吐温-20含量分别为0.2%和0.1%,pH为1.5时制备的浆料有较好的负载率、附着率和NO转化率。而后对整体式蜂窝状V₂O₅-WO₃-TiO₂/堇青石催化剂进行SCR性能测试,其在350~500 ℃区间活性、耐C₃H₈、SO₂和H₂O反应催化活性均在80%以上,在350 ℃时稳定性均高于88%。通过粒径分析、SEM的表征结果表明,该配方制备的浆料能有效减少组分团聚作用,使其小于堇青石孔径,从而拥有较高的负载率和附着率。通过XPS、H₂-TPR和NH₃-TPD的表征结果表明,C₃H₈、SO₂和H₂O物质的加入会使促进反应的活性物质含量降低,与反应物竞争活性位点,从而降低催化剂氧化还原性能,进而影响催化剂催化活性。但在中高温区间,通过该配方制备的催化剂仍保持良好的酸性位和酸性数量,且与反应物竞争作用降低,从而在中高温度区间仍能保持良好的性能。本研究可为涂覆式蜂窝状催化剂的优化合成、提升其去除氮氧化物及抗中毒性能提供参考。