Mn的氧化价态对Mn/γ-Al2O3催化剂催化臭氧氧化气相低浓度甲苯的影响

采用共沉淀法,以Al₂O₃为载体制备Mn/γ-Al₂O₃和Mn-Ce/γ-Al₂O₃催化剂,并分别在N₂气氛和O₂气氛下焙烧。采用固定床连续流动反应器,研究所制备催化剂在室温条件下催化臭氧氧化甲苯的性能。通过XRD、XPS和FTIR等手段对催化剂的结构和组成进行表征。结果表明,Mn/γ-Al₂O₃催化剂具有良好的催化臭氧氧化甲苯和催化臭氧自身分解的性能,共沉淀法制备催化剂的最佳Mn负载量为20%。O₂气氛焙烧和Ce的加入,可以有效提高催化剂的活性和寿命。原因是O₂气氛焙烧和Ce的加入可以提高Mn的氧化价态。催化剂失活的主要原因是有机副产物在催化剂表面吸附堆积,失活催化剂在550℃、空气气氛下焙烧可恢复催化性能。     

Effects of Ce on catalytic combustion of methane over Pd-Pt/Al2O3 catalyst

Activity and stability of 1%Pd-0.2%Pt/Al₂O₃ and 1%Pd-0.2%Pt/0.6%Ce/Al₂O₃ catalysts prepared by impregnation method for catalytic combustion of methane in air were investigated. The catalysts before and after reaction were characterized by BET, CO chemisorption, XRD and XPS techniques. Results showed that the presence of Ce significantly increased the activity and thermal stability of the Pd-Pt/Al₂O₃ catalyst towards methane combustion, which could be attributed to more highly-dispersed active PdO particles over the Pd-Pt/Ce/Al₂O₃ catalyst surface as well as the retarded sintering of PdO and the maintained oxidized state of surface Pd during the combustion process in the presence of Ce.     

富氧条件下NOx催化净化的研究进展

本文对富氧条件下NOx的催化净化进行了综述与探讨,着重分析了分子筛催化剂、贵金属催化剂以及金属氧化物催化剂在碳氢化合物选择性催化还原NOx反应中的活性及其影响因素,描述了催化反应的机理,并指出了今后的研究方向.     

TiO2薄膜气相光催化氧化低浓度三氯甲烷和三氯乙烯的研究

自行设计了气固相光催化实验系统,以铝材为担载体,TCM和TCE为模拟污染物,在常温、常压下,对辐射光源、气体相对湿度、污染物反应浓度等因素对TCM和TCE的光催化降解反应的影响进行了研究.结果表明,在研究所采用的实验条件下,辐射光源采用254 nm时的降解效率要比采用365 nm时高10%左右;气体相对湿度为40%时光催化降解效率最高;随着污染物反应浓度的增加,TCM的降解效率降低,而TCE的降解效率增加.初步的反应动力学研究结果表明,TCM和TCE在二氧化钛表面的光催化降解反应可采用Langmuir-Hinshelwood动力学方程来表征.     

富氧条件下选择性还原NO的复合催化剂体系

选择性催化还原法是净化稀燃汽车尾气中NOx 的最有效途径之一 ,单一催化组分或单一类型的催化剂很难满足实际需要 ,复合催化剂的研究成为必然趋势。本文介绍了复合催化体系的组合形式 ,回顾了国内外最近几年复合催化剂体系净化NOx 的研究成果 ,为将来设计新的复合催化体系提出了建议     

我国室内空气污染现状、成因与对策

室内空气污染严重影响公众健康 ,已经受到广泛关注。本文分析了我国室内空气污染的现状和成因 ,并从法规建设、监督管理、科学研究和宣传教育等方面介绍了我国控制室内空气污染的对策措施     

Determination of gaseous semi- and low-volatile organic halogen compounds by barrier-discharge atomic emission spectrometry

A group parameter approach using "total organic halogen" is effective for monitoring gaseous organic halogen compounds, including fluorine, chlorine, and bromine compounds, generated from combustion. We described the use of barrier-discharge radiofrequency- helium-plasma/atomic emission spectrometry, for the detection of semi- and low-volatile organic halogen compounds (SLVOXs), which can be collected by Carbotrap TM adsorbents and analyzed using thermal desorption. The optimal carrier gas flow rates at the injection and desorption lines were established to be 100 mL/min. The detection range for SLVOXs in the gaseous samples was from 10 ng to tens of micrograms. Measuring F was more difficult than measuring Cl or Br, because the wavelength of F is close to that of air. The barrier- discharge radiofrequency-helium-plasma/atomic emission spectrometry measured from 85% to 103% of the SLVOXs in the gas sample. It has been found that Carbotrap B is appropriate for high-boiling-point compounds, and Carbotrap C is suitable for the determination of organic halogen compounds with lower boiling points, in the range 200-230°C. Under optimal analysis conditions, a chlorine- containing plastic was destroyed using different oxygen concentrations. Lower oxygen concentrations resulted in the production of lower amounts of organic halogen compounds.     

Promoting effect of Zr on the catalytic combustion of methane over Pd/γ-Al2O3 catalyst

The effect of Zr on the catalytic performance of Pd/y-A1203 for the methane combustion was investigated. The results show that the addition of Zr can improve the activity and stability of Pd/γ-Al2O3 catalyst, which, based on the catalyst characterization （N2 adsorption, XRD, CO- Chemisorption, XPS, CHa-TPR and O2-TPO）, is ascribed to the interaction between Pd and Zr. The active phase of methane combustion over supported palladium catalyst is the Pd^0/Pd^2＋ mixture. Zr addition inhibits Pd aggregation and enhances the redox properties of active phase Pd^0/ Pd^2＋. H2 reduction could effectively reduce the oxidation degree of Pd species and regenerate the active sites （Pd^0/ pd^2＋）.     

医院典型废水处理工艺单元的抗生素去除效果与评价

采用固相萃取-高效液相色谱法同时检测了医院废水中2种喹诺酮类(氧氟沙星、环丙沙星)和4种磺胺类(磺胺嘧啶、磺胺甲基嘧啶、磺胺二甲基嘧啶、磺胺甲叶恶唑)抗生素,并对医院废水处理工艺的抗生素去除能力进行了评价。结果表明,现行医院废水处理工艺对抗生素的去除能力介于36.3%~100%,废水处理工艺对医院废水中抗生素的去除能力由大到小为:"厌氧池→好氧池→沉淀池→加氯""化粪池→加氯""好氧池→沉淀池→加氯";"厌氧池→好氧池→沉淀池→加氯"工艺对磺胺嘧啶和磺胺甲叶恶唑去除率达到100%,氧氟沙星和环丙沙星的去除率分别为92.5%和95.6%,磺胺甲基嘧啶的去除率为45.8%;"化粪池→加氯"工艺对磺胺甲基嘧啶和磺胺甲叶恶唑去除率达到100%,氧氟沙星的去除率达到97.4%,环丙沙星、磺胺嘧啶和磺胺二甲基嘧啶的去除率分别为75.0%、57.9%、36.3%;"好氧池→沉淀池→加氯"工艺对磺胺甲基嘧啶去除率达到100%,氧氟沙星、环丙沙星和磺胺甲叶恶唑的去除率分别为59.5%、10.9%和53.8%;厌氧单元对氧氟沙星去除效果较差,对磺胺嘧啶去除效果较好;纯氧曝气好氧单元对环丙沙星、磺胺甲基嘧啶、磺胺二甲基嘧啶、磺胺甲叶恶唑和氧氟沙星的去除率分别为76.0%、62.5%、77.3%、68.4%和13.9%;加氯消毒单元对磺胺二甲基嘧啶的去除效果较差,对磺胺甲叶恶唑的去除效果较好,对其他4种抗生素的去除率也能达到50%以上。     

双酚AF对雄性斑马鱼卵黄蛋白原水平与芳香化酶基因表达的影响

双酚AF(4,4'-六氟-2-二酚,BPAF)对生物有机体具有内分泌干扰作用。为研究低剂量BPAF对水生生物的效应,本研究选择成年雄性斑马鱼为研究对象,考察了0.005、0.05和0.5 mg·L~(-1)3种浓度BAPF暴露30 d对血浆中卵黄蛋白原(VTG)含量、2种卵黄蛋白原基因(vtg~(-1)和vtg-3)表达和2种芳香酶基因(cyp 19a与cyp 19b)表达的影响。结果表明:在0.005 mg·L~(-1)浓度暴露30 d后,血浆中VTG含量显著升高,随着暴露浓度的升高,促进作用不显著;BPAF暴露对不同组织中的4种基因存在不同的影响,0.005 mg·L~(-1)BPAF暴露可诱导脑部cyp19b、肝脏中cyp19a和性腺中vtg~(-1)、vtg-3和cyp19b基因表达;0.5 mg·L~(-1)BPAF暴露可导致肝脏中vtg~(-1)、vtg-3、性腺中cyp19a等基因显著上调。实验结果表明,BPAF具有雌性激素样效应,可诱导雄性斑马鱼体内部分组织卵黄蛋白原基因和芳香酶基因的表达。BPAF可引起斑马鱼血浆中的VTG含量的上升,从而干扰由VTG所参与的下丘脑-垂体-性腺轴与免疫系统的正常生理过程。