Heterogeneous oxidation of carbonyl sulfide on mineral oxides

Heterogeneous oxidation of carbonyl sulfide (OCS) on mineral oxides including SiO2,Fe2O3,CaO,MgO,ZnO and TiO2,which are the main components of atmospheric particles,were investigated using in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS),ion chromatography (IC),temperature-programmed desorption (TPD),X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) methods. The main products and intermediates of the heterogeneous oxidation of OCS on these oxides were identified with in situ DRIFTS and IC. The reaction mechanism and kinetics were also discussed. It is found that the reaction mechanism on these mineral oxides is the same as that on Al2O3 for the same final products and the intermediates at room temperature. Namely,OCS can be catalytically oxidized to produce surface SO42- species and gaseous CO2 through the surface hydrogen thiocarbonate (HSCO2-) and HSO3- species. The activity series for heterogeneous oxidation of OCS follows: Al2O3 ≈ CaO > MgO > TiO2 ≈ ZnO > Fe2O3 > SiO2. The specific area,basic hydroxyl and surface basicity of these oxides have effect on the reactivity. This study suggests that heterogeneous reactions of OCS on mineral dust may be an unneglectable sink of OCS.     

Heteroseneous oxidation of carbonyl sulfide on mineral oxides

Heterogeneous oxidation of carbonyl sulfide （OCS） on mineral oxides including SiO2, Fe2O3, CaO, MgO, ZnO and TiO2, which are the main components of atmospheric particles, were investigated using in situ diffuse reflectance infrared Fourier transform spectroscopy （in situ DRIFTS）, ion chromatography （IC）, temperature-programmed desorption （TPD）, X-ray diffraction （XRD） and Brunauer-Emmett-Teller （BET） methods. The main products and intermediates of the heterogeneous oxidation of OCS on these oxides were identified with in situ DRIFTS and IC. The reaction mechanism and kinetics were also discussed. It is found that the reaction mechanism on these mineral oxides is the same as that on Al2O3 for the same final products and the intermediates at room temperature. Namely, OCS can be catalytically oxidized to produce surface SO4^2- species and gaseous CO2 through the surface hydrogen thiocarbonate （HSCO2-） and HSO; species. The activity series for heterogeneous oxidation of OCS follows： Al2O3 ≈ CaO 〉 MgO 〉 TiO2 ≈ ZnO 〉 Fe2O3 〉 SiO2. The specific area, basic hydroxyl and surface basicity of these oxides have effect on the reactivity. This study suggests that heterogeneous reactions of OCS on mineral dust may be an unneglectable sink of OCS.     

羰基硫水解催化剂的失活行为研究

研究了羰基硫水解催化剂TGH－2在低浓度氧气存在下的失活行为,考察了温度、氧气浓度、羰基硫进口浓度对催化剂活性的影响,并用扫描电镜能谱联合装置对使用前后的催化剂进行分析,得到了较好的结果,其结果对工业应用有指导作用。     

Atmospheric heterogeneous reaction of acetone: Adsorption and desorption kinetics and mechanisms on SiO2 particles

Acetone plays an important role in photooxidation processes in the atmosphere. Up to date, little is known regarding the heterogeneous fate of acetone. In this study, the adsorption and desorption processes of acetone on SiO2 particles, which are the major constituent of mineral dust in the atmos-phere, have been investigated for the first time under the simulated atmospheric conditions, using in situ transmission Fourier transform infrared spectroscopy. It is found that acetone molecules are adsorbed on the surfaces of SiO2 particles by van der Waals forces and hydrogen bonding forces in a nonreactive and reversible state. The rates of initial adsorption and initial desorption, initial uptake coefficients and adsorption concentrations at equilibrium have been determined at different relative humidity. The presence of water vapor cannot result in the formation of new substances, but can decrease the adsorption ability by consuming or overlapping the isolated OH groups on the surfaces of SiO2 particles. In the desorption process, a considerable amount of acetone molecules will remain on SiO2 particles in dry air, whereas acetone molecules are almost completely desorbed at a high relative humidity. In order to evaluate the role of heterogeneous reactions of acetone and other carbonyl compounds in the atmosphere, a new model fitting the atmospheric conditions is needed.     

Atmospheric heterogeneous reaction of acetone:Adsorption and desorption kinetics and mechanisms on SiO_2 particles

Acetone plays an important role in photooxidation processes in the atmosphere. Up to date, little is known regarding the heterogeneous fate of acetone. In this study, the adsorption and desorption processes of acetone on SiO2 particles, which are the major constituent of mineral dust in the atmos-phere, have been investigated for the first time under the simulated atmospheric conditions, using in situ transmission Fourier transform infrared spectroscopy. It is found that acetone molecules are ad-sorbed on the surfaces of SiO2 particles by van der Waals forces and hydrogen bonding forces in a nonreactive and reversible state. The rates of initial adsorption and initial desorption, initial uptake coefficients and adsorption concentrations at equilibrium have been determined at different relative humidity. The presence of water vapor cannot result in the formation of new substances, but can de-crease the adsorption ability by consuming or overlapping the isolated OH groups on the surfaces of SiO2 particles. In the desorption process, a considerable amount of acetone molecules will remain on SiO2 particles in dry air, whereas acetone molecules are almost completely desorbed at a high relative humidity. In order to evaluate the role of heterogeneous reactions of acetone and other carbonyl compounds in the atmosphere, a new model fitting the atmospheric conditions is needed.     

粉煤灰催化空气氧化硫化钠溶液的研究

在溶液温度为30～60℃时，研究了热电厂粉煤灰作为空气氧化硫化钠溶液的非均相催化剂，并对粉煤灰来源和用量、搅拌速度、反应温度、粒度和空气流速等因素对反应的影响进行了探讨。结果表明粉煤灰具有良好的催化活性，在溶液温度为30℃，粉煤灰用量为4％(质量分数，％)时，反应速率是无灰时的3．5倍，催化氧化反应的活化能为：10.868KJ/mol：空气流速从0.05--0.60L/s变化时，S^2 的氧化速率不受空气流速的影响。与新灰相比，五次重复旧灰的活性下降了约30％。     

羰基铁粉形貌对吸波性能的影响

由于羰基铁粉具有温度稳定性好、吸收频带宽、可设计性强等优点,从而得到了广泛的研究与应用。对两种参数基本一致,但形貌各异的羰基铁粉(球状和树枝状)进行了电磁吸波性能测试,用以研究形貌对羰基铁粉电磁吸波性能的影响。实验结果表明,形貌对羰基铁粉的电磁吸波性能有非常大的影响。相比于球状羰基铁粉,树枝状羰基铁粉的最大反射损耗增加了94%,达到-47.14dB。同时,对应于最大反射损耗的频率从球状羰基铁粉的11.88GHz移动到树枝状羰基铁粉的6.44GHz。这是因为树枝状形貌有利于形成不连续网络、增加对入射微波的漫反射、还可以带来更多的界面电荷极化,从而增强对电磁波的吸收强度。此外,本研究表明各向异性结构是提高介电常数和介电损耗获得轻质宽带吸波剂的有效途径。     

钴掺杂硫化锌催化剂的制备及其电催化析氢性能

以硝酸钴、硝酸锌为主要原料,分别采用L-半胱氨酸和硫脲为硫源制备钴掺杂硫化锌,借助XRD、SEM、TEM等对其形貌及结构进行表征,并通过析氢实验探讨不同硫化方式对钴掺杂硫化锌电催化性能的影响。结果表明,以L-半胱氨酸硫化法制备的钴掺杂硫化锌催化剂结晶度高且具有更好的电催化析氢效果。     

Effect of manganese sulfide on the precipitation behavior of tin in steel

Tramp elements such as tin are considered harmful to steel because of hot brittleness they induce at high temperatures. Because tramp elements retained in steel scrap will be enriched in new steel due to the difficultly of their removal, studies on the precipitation behavior of tin are essential. In this study, the effects of different inclusions on the precipitation behavior of tin in steel were studied. The results show that the tin-rich phase precipitates at austenite grain boundaries in an Fe-5%Sn alloy without MnS precipitates, whereas Sn precipitates at the boundaries of MnS inclusions in steel that contains MnS precipitates. MnS is more effective than silicon dioxide or aluminum oxide as a nucleation site for the precipitation of the tin phase, which is consistent with the disregistry between the lattice parameters of the tin phase and those of the inclusions.     

上海地区2017年夏季大气中羰基化合物的空间分布特征

使用实验室自主研发的多通道含氧挥发性有机物(oxygenated volatile organic compound,OvOC)远程控制采样器,于2017年8月4-7日对上海地区20个监测站点在早高峰(6:00-9:00)时段同步采集大气中20种羰基化合物,并利用2,4-二硝基苯肼(dinitrophenylhydra...     

大气颗粒物的表面电特性和界面酸-碱反应特征平衡常数

采用质量滴定法测定了大气颗粒物的零净电荷点(pH(PZNC)),甲醛缩合法测定了结构电荷密度(σst),进而得到界面酸-碱反应特征平衡常数(1-pK模型中的K,2-pK模型中的Kinta1和Kinta2)。结果表明,所研究的大气颗粒物样品荷结构负电荷,σst=-0.18mmol/g;存在与电解质浓度无关的零净电荷点,pH(PZNC)=8.00;界面酸-碱反应特征平衡常数分别为pK=8.00,pKinta1=2.07和pKinta2=13.93。     

基于OPAC的典型环境中气溶胶组分的光学特性分析

利用基于Mie散射理论的云和气溶胶粒子的光学特性软件(OPAC)在不同激光雷达探测波段对一般大陆(典型气溶胶组分:水溶性、不溶性和烟尘气溶胶)、沙漠(典型气溶胶组分:水溶性、核模态矿物、积聚模态矿物和粗模态矿物气溶胶)和洁净海洋(典型气溶胶组分:水溶性、积聚模态海盐和粗模态海盐)3种环境下的气溶胶光学参数(散射系数、光学厚度和激光雷达比)进行了仿真研究,分析了各环境中光学参数随气溶胶组分数浓度的变化规律以及各组分对光学特性的影响.结果表明消光系数和光学厚度在不同激光波段、不同环境下均随组分数浓度线性递增,在上述环境中对消光系数和光学厚度影响最大的组分依次为水溶性气溶胶、积聚模态矿物气溶胶和积聚模态海盐气溶胶.激光雷达比变化规律十分复杂,受探测波长及气溶胶组分的双重影响,一般大陆环境中非水溶性气溶胶在2个波段上的影响占主导地位;沙漠环境中,不同波段上积聚模态矿物气溶胶对激光雷达比的影响最大;洁净海洋环境中,积聚模态海盐气溶胶对激光雷达比的影响最强.     

蒸汽相变与撞击流耦合促进细颗粒物脱除

针对石灰石/石膏法湿式烟气脱硫(WFGD)工艺,考察了WFGD系统对烟气温湿度和细颗粒形貌与元素组成的影响,并分析了相变室中过饱和水汽环境的形成特性;在此基础上,采用蒸汽相变和撞击流耦合的方法,实验研究了撞击流相变室中应用蒸汽相变促进细颗粒物脱除的效果,并与普通蒸汽相变室进行了比较.结果表明:细颗粒经石灰石/石膏法脱硫...     

FexO-TiO2体系的固相反应机理

采用扩散偶法研究了1323 ～ 1473 K 下 FexO-TiO2体系的固相反应,反应过程中氧分压由一定比例的CO-CO2混合气体控制.扩散偶截面的微观形貌用电子探针进行观察,并对Fe2+、Ti4+和O2-离子的扩散浓度轮廓进行定量分析.结合FeO-TiO2体系相图确定了同相反应中有钛铁晶石、钛铁矿和假铁板钛矿相生成,且它们的生长受扩散控制.依据扩散组元的摩尔分数变化绘制了铁离子的扩散路径图,并在此基础上描述了该体系的同相反应机理.     

OXO(X=Cl,Br)自由基与CO和NO自由基反应机理的理论研究

对CO和NO自由基与OXO(X=Cl,Br)自由基反应机理进行了理论研究.在MP2/6-311 +G(d,P)水平下优化了反应物、产物、中间体和过渡态的几何构型,并对所有平衡构型进行了简谐振动频率分析.在相同的计算水平下以过渡态为出发点,利用内禀反应坐标(IRC)理论得到了反应的最小能量路径(MEP),能量信息的进一步校正在较高的MCQCISD//MP2/6-311+G(d,p)水平下完成.研究结果表明,该反应体系可发生氧抽提反应,其中NO与OClO的反应是最具有动力学优势的.     

A kinetic study of the reaction of ozone with ethylene in a smog chamber under atmospheric conditions

Ozone is one of the key species in the processes of atmospheric chemistry, which can be taken as an indicator of oxidation capacity in the troposphere. The reaction of ozone with reactive gases is an important process in the troposphere. Experimental simulation equipment of smog chamber for atmospheric reactions is used to study the reaction of ozone with ethylene in real atmospheric environment with ozone concentrations of 100―200 ppb. The concentrations of ozone and ethylene were moni-tored during the reaction with the combination of Model 49C-O_3 Analyzer and GC-FID. A rate constant of 1.01×10~(-18) (cm~3·mol~(-1)·s-(~1)) was obtained at 286.5 K, under condition of which the half-life of ozone was 88 min. The results obtained from our experiments are in excellent agreement with those reported previously by other researchers under extremely low pressure in terms of matrixisolation technology. This demonstrates that our equipment of smog chamber for atmospheric reactions is reliable, which can be used for further research of the processes of atmospheric reactions.     

Cl＋CH2ICl反应机理的理论研究

利用从头算方法,对多通道反应体系Cl CH2ICl的反应机理进行了理论研究.在MP2/3-21G(d,p)水平下,优化了反应物、络合物、产物和过渡态的几何构型,并对得到的平衡几何构型进行了简谐振动频率分析.在相同水平下,以过渡态为出发点,通过内禀反应坐标理论计算了反应的最小能量路径.并且在QCISD(T)/MIDIX高水平下进行了单点能量校正.结果表明:反应存在6条可行的反应通道,其中生成ICl和CH2Cl的通道为主反应通道,其他反应通道为次要反应通道.     

硫酸化改性对TiO2负载的铈基脱硝催化剂的活性及抗碱金属性能的影响

采用浸渍法对TiO₂负载的铈基催化剂进行了硫酸化改性,同时制备了未经硫酸化改性的催化剂与之对比,通过X射线衍射（XRD）、比表面积测试（BET）、氢气程序升温还原（H₂-TPR）、X射线光电子能谱（XPS）和吡啶红外光谱（Py-IR）等一系列手段对催化剂进行了表征。结果表明,硫酸化改性不仅能够增加催化剂表面的化学吸附氧的含量,提高催化剂的氧化还原性,而且还能极大地丰富催化剂表面的布朗斯特酸位点和路易斯酸位点,以此来增加催化剂的酸性,使得催化剂的低温活性有所提升并拓宽其温度窗口。此外,硫酸化改性为铈基催化剂表面增加了额外的超强酸位点,使催化剂在受到碱金属的毒害后,仍有大量的酸位能得以保留,能够维持对NH₃的吸附,进行催化反应循环,极大地提升催化剂的抗碱金属性能。     

大牛地奥陶系马五段硫化氢腐蚀机理与影响因素

为了解决大牛地气田硫化氢腐蚀严重问题,分析了硫化氢腐蚀机理以及影响腐蚀程度的因素。结合大牛地奥陶系马家沟组马五段地质条件以及硫化氢赋存条件确定该区域硫化氢形成的机理,为硫酸盐热化学还原反应;且该区域存在的大量石膏层为含硫化氢气体提供了良好的圈闭条件。硫化氢腐蚀模拟试验模拟了马五段地层水环境对N80钢和P110钢的腐蚀程度,P110钢的腐蚀程度较N80钢轻微,两者均属于极严重腐蚀。结合腐蚀表面微观形貌观测与腐蚀产物能谱分析得出:大牛地奥陶系马家沟组马五段硫化氢腐蚀机理为高温高压下CO2/H2S电化学腐蚀为主;并伴随有高Cl-破坏腐蚀产物膜加速腐蚀。硫化氢腐蚀影响因素分析得出温度和CO2含量增加会加速硫化氢腐蚀。     

成都市十里店地区大气气溶胶元素组成及来源解析

采用等离子体原子吸收光谱法(ICP-AES)分析了成都市十里店地区大气气溶胶的元素组成,并运用富集因子和因子分析方法对气溶胶的元素富集状况及其来源进行了解析.结果表明:该地区大气气溶胶中Ca,Cu,Zn,As,Pb,Cd和Hg等有毒有害元素富集程度高,对人体和环境危害大.气溶胶主要来源于地面扬尘、冶金化工尘、燃煤和燃油尘.