CNTs-CeO2/H2O2复合光催化氧化体系降解水中酸性橙Ⅱ

运用"化学沉淀法",将CeO2负载到碳纳米管(CNTs)上制备复合光催化剂,采用"单因素实验法"优化了制备条件。运用透射电镜和X射线衍射仪对复合光催化剂进行了表征。结果表明,负载到CNTs上的CeO2为多晶面心立方结构,尺寸大小在6~10 nm之间,其在CNTs上分散效果好,负载均匀且负载率高。在溶液pH为5,CNTs-CeO2用量为0.50 g/L并光照2 h后,酸性橙Ⅱ的光脱色率和TOC去除率分别达到64.71%和44.25%;加入0.02 mmol/L H2O2后,CNTs-CeO2/H2O2复合体系对酸性橙Ⅱ的光脱色率和TOC去除率分别提高至91.35%和82.40%。这预示着CNTs-CeO2/H2O2复合光催化氧化体系在对水中偶氮染料的光催化处理方面具有潜在的应用价值。     

黄土对钕(Ⅲ)和铈(Ⅲ)在不同pH下的等温吸附特性

研究了黄土对钕 (Ⅲ )和铈 (Ⅲ )在不同pH下的等温吸附特性 ,采用Langmuir及Freundlich两种吸附模型对吸附数据进行了描述 .并分析、比较了线性及非线性两种拟合的方法 .非线性拟合 ,由于数据形式没有转换 ,求得的模型参数较线性方法比较可靠 ;非线性拟合结果表明 ,在低pH( =3 ,5 75 )下 ,等温吸附行为更符合Langmuir模型 ,而在高pH( =6 1,6 9)下 ,更符合Freundlich模型     

有机酸在金属氧化物上的吸附对催化臭氧氧化的影响

以苯甲酸(BA)、邻苯二甲酸(PA)、商品腐殖酸(CHA)和反渗透法提取的松花江水腐殖酸(SHA)为目标物,研究了臭氧氧化及羟基氧化铁(FeOOH)和二氧化铈(CeO₂)为催化剂时的吸附与催化臭氧氧化去除这些有机物的效果.结果表明,BA在FeOOH表面没有吸附,FeOOH对BA催化氧化的去除率比臭氧单独氧化高45%;PA在FeOOH上的吸附使其溶液中的浓度减少了5%,此时FeOOH对PA的氧化没有催化作用.CeO₂有助于催化臭氧氧化在其表面吸附较强的PA,且对氧化产生的草酸根有催化去除作用,但对不吸附在其表面的BA没有催化臭氧氧化作用.CeO₂对腐殖酸的吸附比FeOOH强,其催化臭氧氧化去除腐殖酸的作用比FeOOH更显著;当无机阴离子和腐殖酸竞争金属氧化物表面的吸附位时,催化作用受到抑制.     

A kinetic model of Ti（IV）-catalyzed H2O2/O3 process in aqueous solution

A kinetic model for the Ti(IV)-catalyzed H₂O₂/O₃ process was established, and the experimental results demonstrated that the model could well describe this ozone-based oxidative system mathematically and chemically.     

Catalytic combustion of soot over ceria-zinc mixed oxides catalysts supported onto cordierite

Modified substrates as outer heterogeneous catalysts was employed to reduce the soot generated from incomplete combustion of diesel or diesel/biodiesel blends, a process that harms the environment and public health. The unique storage properties of ceria(CeO2) makes it one of the most efficient catalysts available to date. Here, we proposed that ceria-based catalysts can lower the temperature at which soot combustion occurs; more specifically, from 610℃ to values included in the diesel exhausts operation range(300–450℃). The sol-gel method was used to synthesize mixed oxide-based catalysts(CeO2:ZnO); the resulting catalysts were deposited onto cordierite substrates. In addition, the morphological and structural properties of the material were evaluated by XRD, BET, TPR-H2, and SEM. Thermogravimetric(TG/DTA) analysis revealed that the presence of the catalyst decreased the soot combustion temperature by 200℃ on average, indicating that the oxygen species arise at low temperatures in this situation, promoting highly reactive oxidation reactions. Comparative analysis of soot emission by diffuse reflectance spectroscopy(DRS) showed that catalyst-impregnated cordierite samples efficiently oxidized soot in a diesel/biodiesel stationary motor: soot emission decreased by more than 70%.     

Novel synthetic approaches and TWC catalytic performance of flower-like Pt/CeO2

A novel Ultrasonic Assisted Membrane Reduction （UAMR）-hydrothermal method was used to prepare flower-like Pt/CeO2 catalysts. The texture, physical/chemical properties, and reducibility of the flower-like Pt/CeO2 catalysts were characterized by X-Ray Diffraction （XRD）, Scanning Electron Microscope （SEM）, Transmission Electron Microscope （TEM）, N2 adsorption, and hydrogen temperature programmed reduction （HE-TPR） techniques. The catalytic performance of the catalysts for treating automobile emission was studied relative to samples prepared by the conventional wetness impregnation method. The Pt/CeO2 catalysts fabricated by this novel method showed high specific surface area and metal dispersion, excellent three-way catalytic activity, and good thermal stability. The strong interaction between the Pt nanoparticles and CeO2 improved the thermal stability. The Ce4＋ ions were incorporated into the surfactant chains and the Pt nanoparticles were stabilized through an exchange reaction of the surface hydroxyl groups. The SEM results demonstrated that the Pt/CeO2 catalysts had a typical three-dimensional （3D） hierarchical porous struc- ture, which was favorable for surface reaction and enhanced the exposure degree of the Pt nanoparticles. In brief, the flower-like Pt/CeO2 catalysts prepared by UAMR-hydrothermal method exhibited a higher Pt metal dispersion, smaller particle size, better three-way catalytic activity, and improved thermal stability versus conven- tional materials.     

华东片区Ⅳ级成矿单元划分及成矿地质特征

基于中国大陆东南部的构造—成矿背景及区域矿产分布地质特征,参考华东片区全国Ⅲ级成矿单元划分方案,进一步划分出28个Ⅳ级成矿单元,并论述了其中8个Ⅲ级成矿单元及19个Ⅳ级成矿单元的成矿地质特征。     

Ce改性钒磷氧催化剂的制备及其脱硝性能研究

采用Ce调控负载型钒磷氧（VPO/TiO₂）催化剂的表面酸性并与之形成密切相关的微观结构,研究催化剂VPO-Ce/TiO₂的脱硝性能.结果表明,当P/V为1/3、Ce/V为1/4、活性组分负载量10%、催化剂焙烧温度为400℃时,催化剂的脱硝活性最好,反应温度250~350℃范围内的脱硝率高于96.0%.BET测试结果表明,催化剂0.1VP（0.33）O-Ce（0.25）/TiO₂的比表面积为10.74m²/g,较0.1VP（0.33）O/TiO₂提高了约58.6%.0.1VP（0.33）O/TiO₂表面化学吸附氧（O_α）和晶格氧（O_β）的比例O_α/O_β为72%,掺杂Ce后O_α/O_β升高至85%,Ce掺杂还能促进相邻V⁵⁺和V⁴⁺的形成,提高催化剂的氧化还原性能.Ce掺杂对催化剂的表面酸性影响较大,当Ce/V为1/4时催化剂表面Brønsted酸最强,这与活性测试相吻合.控制烟气中SO₂和水蒸气的体积浓度分别为200×10^-6和4vol.%,催化剂的脱硝活性在150~300℃温度范围内最高下降约15.8%,当温度高于300℃时催化剂的脱硝活性几乎不下降,且反应后的催化剂表面无硫酸根生成,催化剂呈现出较强的抗SO₂和水蒸汽的性能.     

铁铈氧化物对土壤As (Ⅴ)和P的稳定化效果

本文以铁铈氧化物(Fe-Ce,FC)为研究对象,评估其对中国3种典型砷(As)污染土壤的稳定化修复效果,并通过电子扫描显微镜能散X线分析仪(SEM-EDS)和X射线光电子能谱仪(XPS)等光谱学技术探索FC对As(Ⅴ)的微观吸附特征.结果表明,FC能使土壤毒性浸出As含量显著降低84. 1%～98. 3%,且在碱性土壤中表现出较强的高p H适应性,能显著增加吸附态As(F1+F2)向水合铁铝氧化物结合态(F3+F4)的稳定化. FC能使不同类型土壤的有效态P含量显著下降47. 13%～60. 32%,不仅能缓解P竞争土壤As(Ⅴ)吸附位点,而且能有效预防周边水体的面源污染.通过SEM-EDS和XPS分析,发现As(Ⅴ)吸附产物表面均检测到Fe、Ce和As这3种元素,且As主要吸附于Fe原子表面. FC在我国土壤砷污染稳定化修复领域具有较好地应用前景.