High activity of CeO_2-TiO_2 composites for deep oxidation of 1,2-dichloroethane

CeO_2-TiO_2 catalysts prepared by different methods were investigated for deep oxidation of 1,2-dichloroethane(DCE),as a typical representative of the chlorinated volatile organic compounds(CVOCs).Characterization analysis reveals that CeO_2-TiO_2 catalysts prepared by sol-gel and coprecipitation methods exhibit higher specific area,CeO_2 and TiO_2 particles are highly dispersed into each other and the reducibility and mobility of active oxygen species are obviously promoted due to the strong interaction between the two catalysts CeO_2 and TiO_2,resulting in higher catalytic activity for DCE oxidation to and less chlorinated byproduct.The high calcination temperature would lead to the formation of a new monoclinic phase Ce_(0.3)Ti_(0.7)O_2 and sintering,which is the main reason for the catalytic activity for DCE oxidation markedly decreases.     

Effect of Ce doping into V_2O_5-WO_3/TiO_2 catalysts on the selective catalytic reduction of NO_x by NH_3

In this work, the effectiveness of V_2O_5-WO_3/TiO_2 catalysts modified with different CeO_2 contents by impregnation and co-precipitation methods on the selective catalytic reduction of NOxby NH3 have been studied comparatively by various experimental techniques. The results showed that the NO conversion of V_2O_5-WO_3/CeO_2-TiO_2 catalysts modified by co-precipitation method obviously increased with the Ce doping contents in the studied range below 20%(All Ce contents are in mass fractions), but the NO conversion of V_2O_5-WO_3/CeO_2/TiO_2 catalysts modified by impregnation methods was lower than V_2O_5-WO_3/CeO_2-TiO_2 catalysts especially beyond 2.5% Ce doping contents. The V_2O_5-WO_3/CeO_2-TiO_2 catalysts showed better SCR activity, wider reaction window, and higher sulfur and water resistance. The characterization results elucidated that the modified catalysts by co-precipitation method exhibited higher specific surface area, much better dispersity of Ce component, more Ce~(3+)species and more Br?nsted acid sites than that by impregnation. The vacancies caused by more Ce~(3+)species were favorable for more NO oxidation to NO_2, and the interaction between Ce species and WOxspecies generated more Br?nsted acid sites. It could be supposed that dispersed Ce Oxspecies and WOxspecies offered more second active centers respectively to adsorb oxygen and activate ammonia as co-catalysis to the primary active center of V ions, thus facilitated the better SCR activity of modified V_2O_5-WO_3/CeO_2-TiO_2 catalysts by coprecipitation methods. The co-precipitation methods with Ce component were more suitable for production of modified commercial V_2O_5-WO_3/TiO_2 catalysts.     

聚合物稳定的Au-Pd/TiO2-Al2O3催化剂的还原方法及其催化性能的研究

以PVP为稳定剂，乙醇和K1BH4为还原剂制备了Au-Pd／TiO2-Al2O3催化剂，考察了还原剂对Au-Pd负载型双金属催化剂加氢脱硫性能的影响，并运用XRD，TPD，TPR等技术对催化剂进行表征。结果表明，以乙醇还原的Au-Pd／TiO2-AlO3催化剂的加氢脱硫活性较好。乙醇还原的Au-Pd／TiO2．Al2O3催化剂中Au-Pd之间及活性组分与载体之间的相互作用较强，形成Au-Pd，合金的晶粒较小，活性组分的分散度和活性表面积较大，反应活化能较低，这些均有利于催化剂活性的提高。     

高炉渣的偏振化能量色散X射线荧光光谱分析

用带有Mo,Al2O3和HOPG3个次级靶的偏振化能量色散X射线荧光光谱仪,成功地分析了高炉渣中MgO,Al2O3,CaO,SiO2,S,TiO2,MnO和TFe。高炉渣中主要成分SiO2,Al2O3,CaO,MgO相互之间的干扰,使用Luscas Tooth和Price经验系数法校正。总的测量时间为600s,结果能满足冶金生产的要求。     

ICP-AES法测定冶金炉渣中氧化物及全铁

提出用ICP AES分析法测定冶金炉渣中SiO2,Al2O3,CaO,MgO,MnO,TFe,P2O5,TiO2等成分。试样经常规熔融处理及稀释后,用工作曲线法测定,各组分的测量范围0.01%～50.0%,经与化学法对照,效果满意,可取代化学方法。     

电感耦合等离子体发射光谱法测定石灰石、白云石中的多元素

研究了ICP-AES法同时测定石灰石、白云石中多元素的方法,经试验确定了溶样条件I、CP分析条件及各元素的特征分析谱线。该方法简洁快速,结果满意,适用于石灰石、白云石中SiO2、CaO、MgO、Fe2O3、Al2O3、MnO、P、TiO2、SrO、K2O、和Na2O的同时测定。     

X-射线荧光光谱法测定炉渣中13种组分

采用Li2B4O7和LiNO3为熔剂,LiBr作脱膜剂,熔融法制备样品;运用干扰曲线法通过迭次校正Ba,Ti,V,Cr,Mn各元素谱线重叠干扰,理论α系数法校正基体效应,X-射线荧光光谱法(XRF)分析了复杂体系炉渣中Na2O,MgO,Al2O3,SiO2,P2O5,K2O,CaO,TiO2,V2O5,Cr2O3,MnO,TFe,BaO 13种组分。该方法与化学法测定结果符合较好,10次制样测量各组分,相对标准偏差在0.15%~3.79%范围内。     

X-射线荧光光谱法测定铝质耐火材料中主次成分

介绍了熔融制样X-射线荧光光谱法测定铝质耐火材料中Al2O3,SiO2,Fe2O3,TiO2,CaO,MgO,P2O5,K2O等组分的分析方法。采用国家标准物质和以标准物质为基体添加纯试剂合成标样制作工作曲线;研究讨论了熔剂体系及样品的稀释比例、样品的熔融制备、烧失量和基体增强吸收效应的校正。通过对比实验表明,该方法的测定结果准确,能满足耐火材料及其制品常见组分分析的需要。     

321不锈钢中大型夹杂物的研究

采用大样电解方法研究了321不锈钢冶炼连铸过程中大型夹杂物的类型和数量变化,分析了吹氩搅拌对大型夹杂物数量的影响。结果表明：喂钛线前,321不锈钢中的大型夹杂物主要有CaO-SiO2—Al2O3、CaO-MgO-SiO2、SiO2等;喂钛线后,由于[Ti]还原夹杂物中的SiO2,形成部分含TiO2的夹杂物。吹氩采用弱搅拌,不仅可以避免二次氧化,而且能够促使钢中夹杂物上浮。     

电炉钛渣相组成和形成机理研究

采用化学分析、X射线衍射和扫描电镜等分析方法，得出了钛渣的X-射线衍射图、形貌图以及电炉钛渣的相组成，查明了钛渣主要由黑钛石固溶体、塔基石固溶体、硅酸盐玻璃体和游离的TiO2组成。分析了还原剂的配比、熔炼温度、冷却温度等对电炉钛渣相组成的影响。研究了钛渣的相组成和杂质的清除机理。试验为寻求有效的电炉钛渣除杂方法提供了依据。     

高炉渣的冶金性能及造渣制度

针对唐钢高炉大量采用高品位、低SiO2含量、高Al2O3含量的外矿的特点,研究了在新的配矿结构下,炉渣碱度(CaO/SiO2)、MgO含量和Al2O3含量对唐钢高炉炉渣的粘度、熔化性温度、脱硫能力的影响.唐钢高炉合理的造渣制度为:保持炉渣温度稳定,碱度控制在1.10左右,MgO的质量分数控制在11%左右,通过合理配煤,适当使用部分冀东矿的方法尽量降低炉渣的Al2O3含量.     

Experimental and DFT study on cerium inclusions in clean steels

To provide insights into deforming Ce-O-S-Al inclusions in steels and improving the mechanical properties,the evolution process of such harmful inclusions in clean steels was investigated by thermodynamic calculation,metallographic examination and first-principles calculation in this paper.For the tested IF steel,the thermodynamic analysis results are consistent with the calculated formation enthalpy.After Ce addition,the inclusions are transformed from Al₂O₃and TiN-Al₂TiO₅-Al₂O₃to Ce2O₃,Ce₂O₂S,CeAlO₃,TiN-Al₂TiO₅-Ce₂O₃and TiN-Al₂TiO₅-Ce₂O₂S composite inclusions,which can be confirmed by metallographic examination.The elastic constants were calculated,and the bulk modulus,Young's modulus,shear modulus and Poisson's ratio were evaluated by the Voigt-Reuss-Hill(VRH)approximation.All inclusions except Ce₂O₃show apparent brittleness.TiN,Al₂O₃,Al₂TiO₅and CeAlO₃present much higher hardness than iron matrix,while the hardness of Ce2O₃or Ce₂O₂S is close to that of iron matrix.The thermal expansion coefficients of Ce₂O₃and CeAlO₃are close to that of iron matrix,whereas,Ce₂O₂S inclusion has largely different thermal expansion coefficient from iron matrix and may deteriorate the steel performance at higher temperatures.The relatively small differences between Ce inclusions and iron matrix in terms of hardness,toughness,brittleness,and thermal expansion coefficient can explain the improvement of the mechanical properties of the tested steel.     

Synthesis and photoluminescent properties of Eu~(3+)/Dy~(3+) doped SrO-Al_2O_3-SiO_2 glass-ceramics

Eu~(3+)/Dy~(3+) single-doped and co-doped 6SrO-3Al_2O_3-91SiO_2 and 12SrO-6Al_2O_3-82SiO_2 glass and glass-ceramics were synthesized successfully by a sol-gel method. The prepared samples were characterized by the X-ray diffraction, high-resolution transmission electron microscopy, photoluminescent spectra and X-ray photoelectron spectroscopy. The effect of annealing temperature, doped ions and matrix component on the structure and the photoluminescent characteristics was systematically studied. The higher temperature was helpful to form nanocrystals and the amount of SrO and Al_2O_3 could better disperse the rare earth ions in matrix at suitable temperature, and both of them could improve the luminescent intensity. Meanwhile, the doped ions could change the luminescent color by single, codoped and energy transfer. The Sr_2SiO_4 nanocrystals were observed in silicates glasses and became larger with the increase of the annealing temperature and the luminous efficiency of rare-earth(RE) ions could be enhanced when the samples changed from glass state to glass-ceramic state. The results indicated that the photoluminescent properties could be changed through controlling the doped ions, annealing temperature and matrix component.     

电解提取-X射线荧光光谱法测定钢中氧化物夹杂分量

研究了应用X射线荧光光谱仪的微区分析功能测定钢中氧化物夹杂分量的方法。优化了电解提取氧化物夹杂及X射线荧光光谱测定其分量的条件,同时建立了分析方法。实验结果表明,试样在弱酸性电解液并控制电流密度为0.02~0.06 A/cm2的条件下进行电解效果较好,测得氧化物夹杂总量一致。实验确定用X射线荧光光谱仪微区测定氧化物夹杂分量的最少样品量为不少于3 mg。用本法测定样品中氧化物夹杂分量SiO2,Al2O3,CaO,MgO,MnO2,Fe2O3,TiO2,Cr2O3的准确度(σ)为0.096%~0.63%,相对标准偏差小于6%,检出限为0.003×10-6~0.025×10-6。     

高炉渣钾容量的试验研究

为降低碱金属对高炉的危害,提高炉渣的排碱能力,采用气-渣平衡法测定了1 723 K时高炉渣的钾容量.依据广钢实际高炉渣成分,用纯化学试剂配制炉渣,用一定组成K(g)-CO-CO2-Ar混合气体提供一定的氧分压和钾分压.研究表明:试验条件下,w(MgO)和w(A12O3)一定时,钾容量随w(CaO)/w(SiO2)的增大而减小;在w(CaO)/w(SiO2)和w(A12O3)一定时,钾容量随w(MgO)的增大而增大;在w(CaO)/w(SiO2)和w(MgO)一定时,钾容量随w(A12O3)的增大而增大;当[w(CaO) w(MgO)]/w(SiO2)和w(A12O3)固定不变时,增加w(MgO),降低w(CaO),钾容量明显增大.广钢炉渣的合理成分为:w(CaO)/w(SiO2)保持在1.0,w(MgO)保持在12%～15%,w(A12O3)不超过15%.     

X射线荧光光谱法测定氧化锆质耐火材料中主次成分

以无水四硼酸锂和碳酸锂混合熔剂作熔剂,采用玻璃熔片法制样,建立了测定氧化锆质耐火材料中ZrO2、HfO2、Al2O3、SiO2、Fe2O3、TiO2、CaO、MgO、Y2O3等组分的X射线荧光光谱法(XRF)。根据氧化锆质耐火材料中主次成分含量范围,采用有证参考物质和具有成分含量梯度并经其他方法定值的自制标准样品绘制校准曲线。并对熔剂选择、熔融条件及基体效应校正进行了探讨。将X射线荧光光谱法用于3个稳定氧化锆试样的分析,并与ICP-AES法进行比对,测试结果吻合。     

Acid modified carrier on catalytic oxidation of dichloromethane over CeO2/HZSM-5 catalysts

In this study, a series of Hydrogen-Zeolite Socony Mobil-5-X (HZSM-5-X) catalysts were prepared by acid modification, then Ce/HZSM-5-X (X = 0, 0.2, 0.4, 1.0, 2.0) catalysts were prepared by impregnation method. The catalytic performance of the catalysts on dichloromethane (DCM) oxidation was investigated. Through different characterizations, HZSM-5-X exhibit high specific surface area, good redox ability, rich acidity and much suitable acidic site distribution after acid treatment. Among them, Ce/HZSM-5-0.4 shows better catalytic activity with the lowest by-product and the best CO₂ yield. Its T₉₀ is 302 °C and the CO₂ yield of T₉₀ is more than 80 wt%, which demonstrates that the acid modification of carrier plays the positive effect on the catalytic capacity for DCM oxidation.     

Influence of CeO_2 loading on structure and catalytic activity for NH_3-SCR over TiO_2-supported CeO_2

A series of supported CeO_2/TiO_2 catalysts were prepared to explore the influence of CeO_2 loading on these catalysts for the selective catalytic reduction of NO_3 by NH_3(NH_3-SCR).The catalysts were investigated in detail by means of XRD,Raman,H_2-TPR,NH_3-TPD,XPS,in situ DRIFTS,and NH3-SCR reaction.The activity of the catalyst is closely related to the content of CeO_2.When the loading of CeO_2 is near the dispersion capacity(1.16 mmol Ce~(4+)/100 m~2 TiO_2),the catalytic activity is better.This may be because that the dispersed CeO_2 is the active species and the catalyst has appropriate redox property,along with the larger amounts of surface Ce content and surface adsorbed oxygen species.Finally,a possible reaction mechanism via the Langmuir-Hinshelwood(L-H) mechanism is tentatively proposed to further understand the NH_3-SCR reaction.     

岛津多道X射线荧光光谱仪测定高炉渣中硅钙镁铝钛

自制样品,粉末压片,用X荧光光谱仪测定炉渣中的硅钙镁铝钛,试验确定了炉渣试样粒度,压片压力,压片时间。试验测定结果与熔样法测定结果对得很好。分析结果准确,快速,成本低。适合高炉昼夜连续生产的需要。     

钢水精炼配渣模型

考虑钢包带渣量和成分的变化,对CaO-SiO2-MgO-Al2O3(-CaF2)精炼渣系建立配渣模型.模型根据是否用铝还原钢包带渣的SiO2,可分两种情况通过化学计量计算达到目标渣成分时精炼渣各成分加入量.