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液相制备纳米锰锌软磁铁氧体粉体的新方法——氧化–共沉淀相转化法 被引量:8
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作者 李东风 张冬婷 +1 位作者 贾振斌 魏雨 《电子元件与材料》 CAS CSCD 北大核心 2003年第8期31-34,共4页
以低碳铁皮和氧气为主要原料,采用一种新的工艺(氧化–共沉淀相转化法)低温液相制备出了锰锌软磁铁氧体纳米粉体。通过实验研究,详细探讨了共沉淀的pH值对生成物的化学组成和磁性的影响。并通过XRD、TEM和VSM(振动样品磁强计)分别对生... 以低碳铁皮和氧气为主要原料,采用一种新的工艺(氧化–共沉淀相转化法)低温液相制备出了锰锌软磁铁氧体纳米粉体。通过实验研究,详细探讨了共沉淀的pH值对生成物的化学组成和磁性的影响。并通过XRD、TEM和VSM(振动样品磁强计)分别对生成物的结构、形貌和磁性进行了表征。实验发现:当共沉淀的pH值为13时,共沉淀最完全,相转化程度最高,晶化最好,所制备的锰锌铁氧体粉体的磁性最强。产物的晶型为立方晶系的尖晶石型,形貌为球形,粒径约为20 nm。 展开更多
关键词 锰锌铁氧体 纳米粉体 氧化-沉淀相转化
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氧化共沉淀法制备Ce_(0.65)Zr_(0.25)Y_(0.1)O_(1.95)的结构转化过程 被引量:4
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作者 张磊 郑灵敏 +4 位作者 郭家秀 吴冬冬 龚茂初 王健礼 陈耀强 《物理化学学报》 SCIE CAS CSCD 北大核心 2008年第8期1342-1346,共5页
以氨水和碳酸铵为沉淀剂,采用氧化-共沉淀法制备了Ce0.65Zr0.25Y0.1O1.95复合氧化物,并对不同处理温度下制备的样品用热重-差示扫描分析(TG-DSC)、傅里叶变换红外(FT-IR)光谱、X射线衍射(XRD)和表面分析仪(BET)等进行了表征.结果表明,... 以氨水和碳酸铵为沉淀剂,采用氧化-共沉淀法制备了Ce0.65Zr0.25Y0.1O1.95复合氧化物,并对不同处理温度下制备的样品用热重-差示扫描分析(TG-DSC)、傅里叶变换红外(FT-IR)光谱、X射线衍射(XRD)和表面分析仪(BET)等进行了表征.结果表明,共沉淀法得到的沉淀物同时含有羟基和羧基,随着焙烧温度的升高,分别在100-170℃、250-300℃和420-500℃温度范围内先后发生脱水、脱羟基和脱羧基反应,在此过程中固溶体逐渐形成.提出了由沉淀物转变为Ce0.65Zr0.25Y0.1O1.95复合氧化物的结构转变模型. 展开更多
关键词 CeO2-ZrO2-Y2O3 结构转变 氧化-沉淀
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Low-temperature catalytic oxidation of formaldehyde over Co_3O_4catalysts prepared using various precipitants 被引量:22
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作者 范泽云 张志翔 +3 位作者 房文健 姚鑫 邹谷初 上官文峰 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2016年第6期947-954,共8页
Co3O4 catalysts prepared with different precipitants(NH3·H2O,KOH,NH4HCO3,K2CO3 and KHCO3)were investigated for the oxidation of formaldehyde(HCHO).Among these,KHCO3-precipitated Co3O4(KHCO3-Co) was the most... Co3O4 catalysts prepared with different precipitants(NH3·H2O,KOH,NH4HCO3,K2CO3 and KHCO3)were investigated for the oxidation of formaldehyde(HCHO).Among these,KHCO3-precipitated Co3O4(KHCO3-Co) was the most active low-temperature catalyst,and was able to completely oxidize HCHO at the 100-ppm level to CO2 at 90℃.In situ diffuse reflectance infrared spectroscopy demonstrated that hydroxyl groups on the catalyst surface were regenerated by K~+ and CO3^(2-),thus promoting the oxidation of HCHO.Moreover,H2-temperature programmed reduction and X-ray photoelectron spectroscopy showed that employing KHCO3 as the precipitant increased the Co^3+/Co^2+molar ratio on the surface of the Co3O4 catalyst,thus further promoting oxidation.Structural characterization revealed that catalysts precipitated with carbonate or bicarbonate reagents exhibited greater specific surface areas and pore volumes.Overall,these data suggest that the high activity observed during the Co3O4 catalyzed oxidation of HCHO can be primarily attributed to the presence of K~+ and CO3^(2-) on the Co3O4 surface and the favorable Co^3+/Co^2+ ratio. 展开更多
关键词 Formaldehyde oxidation CATALYSIS Cobalt oxide Precipitation method Potassium ion
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铁泥制备纳米四氧化三铁 被引量:9
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作者 徐宁 李云 +2 位作者 黎章 崔其磊 姜蕾蕾 《沈阳化工学院学报》 2007年第4期279-282,共4页
以铁泥为原料,采用氧化-共沉淀相转移法制备纳米四氧化三铁.通过实验确定反应的最佳条件是pH=9,相转化反应温度为80℃,相转化时间为2 h,R=n(Fe3+)/n(Fe2+)为1.75.利用IR、XRD、SEM进行表征,根据Scherrer公试计算产品粒径,平均粒径为62 mm.
关键词 铁泥 纳米四氧化三铁 氧化-沉淀
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Enhanced catalytic activities and selectivities in preferential oxidation of CO over ceria-promoted Au/Al_2O_3 catalysts 被引量:4
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作者 苗雨欣 王静 李文翠 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2016年第10期1721-1728,共8页
The preferential oxidation of CO (CO‐PROX) is a hot topic because of its importance in pro‐ton‐exchange membrane fuel cells (PEMFCs). Au catalysts are highly active in CO oxidation. Howev‐er, their activities ... The preferential oxidation of CO (CO‐PROX) is a hot topic because of its importance in pro‐ton‐exchange membrane fuel cells (PEMFCs). Au catalysts are highly active in CO oxidation. Howev‐er, their activities still need to be improved at the PEMFC operating temperatures of 80–120 &#176;C. In the present study, Au nanoparticles of average size 2.6 nm supported on ceria‐modified Al2O3 were synthesized and characterized using powder X‐ray diffraction, nitrogen physisorption, transmission electron and scanning transmission electron microscopies, temperature‐programmed hydrogen reduction (H2‐TPR), Raman spectroscopy, and in situ diffuse‐reflectance infrared Fourier‐transform spectroscopy. Highly dispersed Au nanoparticles and strong structures formed by Au–support in‐teractions were the main active species on the ceria surface. The Raman and H2‐TPR results show that the improved catalytic performance of the Au catalysts can be attributed to enhanced strong metal–support interactions and the reducibility caused by ceria doping. The formation of oxygen vacancies on the catalysts increased their activities in CO‐PROX. The synthesized Au catalysts gave excellent catalytic performances with high CO conversions (&gt;97%) and CO2 selectivities (&gt;50%) in the temperature range 80–150 &#176;C. 展开更多
关键词 Gold catalysis CERIA ALUMINA Preferential oxidation of carbon monoxide DEPOSITION-PRECIPITATION
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Recovery of copper sulfate after treating As-containing wastewater by precipitation method 被引量:4
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作者 郑雅杰 王勇 +1 位作者 肖发新 罗圆 《Journal of Central South University》 SCIE EI CAS 2009年第2期242-246,共5页
The solid sodium hydroxide neutralized acidic As-containing wastewater till pH value was 6. Green copper arsenite was prepared after copper sulfate was added into the neutralized wastewater when the molar ratio of Cu ... The solid sodium hydroxide neutralized acidic As-containing wastewater till pH value was 6. Green copper arsenite was prepared after copper sulfate was added into the neutralized wastewater when the molar ratio of Cu to As was 2:1 and pH value of the neutralized wastewater was adjusted to 8.0 by sodium hydroxide. The arsenious acid solution and red residue were produced after copper arsenite mixed with water according to the ratio of liquid to solid of 4:1 and copper arsenite was reduced by SO2 at 60℃ for 1 h. The white powder was gained after the arsenious acid solution was evaporated and cooled. Copper sulfate solution was obtained after the red residue was leached by H2SO4 solution under the action of air. The results show that red residue is Cu3(SO3)2·2H2O and the white powder is As2O3. The leaching rate of Cu reaches 99.00% when the leaching time is 1.5 h, molar ratio of H2SO4 to Cu is 1.70, H2SO4 concentration is 24% and the leaching temperature is 80 ℃. The direct recovery rate of copper sulfate is 79.11% and the content of CuSOa·5H2O is up to 98.33% in the product after evaporating and cooling the copper sulfate solution. 展开更多
关键词 As-containing wastewater SO2 AS2O3 copper sulfate copper arsenite RECOVERY
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Recovery of magnetite from FeSO_4·7H_2O waste slag by co-precipitation method with calcium hydroxide as precipitant 被引量:3
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作者 余旺 彭映林 郑雅杰 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第1期62-70,共9页
Proper utilization of the FeSO4·7H2O waste slag generated from TiO2 industry is an urgent need, and Fe3O4 particles are currently being widely used in the wastewater flocculation field. In this work, magnetite wa... Proper utilization of the FeSO4·7H2O waste slag generated from TiO2 industry is an urgent need, and Fe3O4 particles are currently being widely used in the wastewater flocculation field. In this work, magnetite was recovered from ferrous sulphate by a novel co-precipitation method with calcium hydroxide as the precipitant. Under optimum conditions, the obtained spherical magnetite particles are well crystallized with a Fe304 purity of 88.78%, but apt to aggregate with a median particle size of 1.83 μm. Magnetic measurement reveals the obtained Fe304 particles are soft magnetic with a saturation magnetization of 81.73 A-m2/kg. In addition, a highly crystallized gypsum co-product is obtained in blocky or irregular shape. Predictably, this study would provide additional opportunities for future application of low-cost Fe3O4 particles in water treatment field. 展开更多
关键词 FeSO4·7H2O TiO2 industry MAGNETITE CO-PRECIPITATION calcium hydroxide magnetic seeding flocculation
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Sono-assisted preparation of magnetic ferroferric oxide/graphene oxide nanoparticles and application on dye removal 被引量:4
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作者 江国栋 常青 +2 位作者 杨福福 胡晓允 唐和清 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第3期510-515,共6页
A simple ultrasound-assisted co-precipitation method was developed to prepare ferroferric oxide/graphene oxide magnetic nanoparticles(Fe_3O_4/CO MNPs).The hysteresis loop of Fe_3O_4/GO MNPs demonstrated that the sampl... A simple ultrasound-assisted co-precipitation method was developed to prepare ferroferric oxide/graphene oxide magnetic nanoparticles(Fe_3O_4/CO MNPs).The hysteresis loop of Fe_3O_4/GO MNPs demonstrated that the sample was typical of superparamagnetic material.The samples were characterized by transmission electron microscope,and it is found that the particles are of small size.The Fe_3O_4/GO MNPs were further used as an adsorbent to remove Rhodamine B.The effects of initial pH of the solution,the dosage of adsorbent,temperature,contact time and the presence of interfering dyes on adsorption performance were investigated as well.The adsorption equilibrium and kinetics data were fitted well with the Freundlich isotherm and the pseudosecond-order kinetic model respectively.The adsorption process followed intra-particle diffusion model with more than one process affecting the adsorption of Rhodamine B.And the adsorption process was endothermic in nature.Furthermore,the magnetic composite with a high adsorption capacity of Rhodamine B could be effectively and simply separated using an external magnetic field.And the used particles could be regenerated and recycled easily.The magnetic composite could find potential applications for the removal of dye pollutants. 展开更多
关键词 Fe3O4/graphene oxide nanoparticles Sonochemical synthesis Adsorption Kinetic modeling Equilibrium Regeneration
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Effect of pH Values on the Formation of Magnesia Doped Zirconia by Bali-Mill Assisted Co-precipitation Method
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作者 Sukhbayar Gankhuyag Dong Sik Bae 《Journal of Physical Science and Application》 2016年第5期31-36,共6页
We have studied the effect of magnesia (MgO) addition (0, 5, 10, and 20 mol%) in zirconia at pH values (7, 9, 11). The magnesia doped zirconia (MgO-ZrO2) has been synthesized by a co-precipitation method using... We have studied the effect of magnesia (MgO) addition (0, 5, 10, and 20 mol%) in zirconia at pH values (7, 9, 11). The magnesia doped zirconia (MgO-ZrO2) has been synthesized by a co-precipitation method using ammonium hydroxide as a mineralizer. As-prepared samples were characterized by XRD, FE-SEM, and TG-DSC. The XRD results showed that the quantity of tetragonal phase was increased with increasing pH value during synthesis. On the other hand, a decrease in the crystallite size of tetragonal phase was observed with increasing pH value. Therefore, the FE-SEM micrograph showed a clear decline in the particle size with increasing pH value. As-precipitated at pH-11, the addition of 10 mol% of MgO showed nearly pure tetragonal phase with a crystallite size of-34.16 nm. 展开更多
关键词 ZIRCONIA phase-stabilization MAGNESIA CO-PRECIPITATION sintering.
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制备条件对煤临氢液化催化剂晶相组成的影响
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作者 王昱心 李茂林 孙昱东 《石油炼制与化工》 CAS CSCD 北大核心 2022年第5期7-13,共7页
以FeSO_(4)·7H_(2)O为铁源,采用沉淀-氧化法在不同条件下制备煤临氢缓和液化的煤载铁系催化剂,利用X射线衍射、扫描电镜和N2吸附-脱附对催化剂进行表征,探究制备温度、制备时间、铁煤比对催化剂晶相组成、分布和活性的影响.结果表... 以FeSO_(4)·7H_(2)O为铁源,采用沉淀-氧化法在不同条件下制备煤临氢缓和液化的煤载铁系催化剂,利用X射线衍射、扫描电镜和N2吸附-脱附对催化剂进行表征,探究制备温度、制备时间、铁煤比对催化剂晶相组成、分布和活性的影响.结果表明:随着制备温度升高,催化剂的α-FeOOH和γ-FeOOH晶相结晶度提高,进一步升高温度,催化剂晶相向低活性的γ-Fe_(2)O_(3)转化;在适宜制备时间内增加制备时间可以提高催化剂中α-FeOOH和γ-FeOOH晶相的结晶度,制备时间过长时会生成少量γ-Fe_(2)O_(3)晶相;较小的铁煤比有利于生成α-FeOOH和γ-FeOOH晶相,但铁煤比过小会使催化剂中α-FeOOH和γ-FeOOH晶相的结晶度降低,铁煤比过大时会生成γ-Fe_(2)O_(3)晶相. 展开更多
关键词 沉淀-氧化法 煤载铁系催化剂 制备条件 液体收率 晶相
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TiO2 preparation by improved homogeneous precipitation and application in SCR catalyst 被引量:3
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作者 YAO Jie 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第9期2139-2145,共7页
Ultrasonic treatment and hydrothermal method were applied in the traditional homogeneous precipitation for nano-TiO_2 preparation, which was used as carrier material for the production of honeycomb selective catalytic... Ultrasonic treatment and hydrothermal method were applied in the traditional homogeneous precipitation for nano-TiO_2 preparation, which was used as carrier material for the production of honeycomb selective catalytic reduction(SCR) catalyst. The influence rules of the two improved methods on characterization of TiO_2 samples, denitration activity and mechanical strength of honeycomb SCR catalyst samples were mainly focused on. The results indicate that the specific surface area, particle size and uniformity of TiO_2 samples are significantly improved by both of the ultrasonic and hydrothermal treatments compared with the traditional homogeneous precipitation. Also, the denitration activities of catalyst samples are enhanced by the two improved methods(the NO_x reduction ratio increases from 88.89% to 95.45% by ultrasonic homogeneous precipitation process, and to 94.12% by hydrothermal homogeneous precipitation process). On the other hand, because of good spherical shape and high particle distribution of TiO_2 sample from hydrothermal homogeneous precipitation process, the corresponding honeycomb catalyst samples get the best mechanical strength, which is even higher than that of the reference sample from commercial nano-TiO_2. So, it is concluded that the hydrothermal homogeneous precipitation can be a feasible and effective preparation method of TiO_2 carrier for the honeycomb SCR catalyst production. 展开更多
关键词 NANO-TIO2 honeycomb SCR catalyst homogeneous precipitation ultrasonic treatment hydrothermal method
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氯雷他啶系列药物中间体生产废水的治理
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作者 杨光丽 《辽宁化工》 CAS 2008年第5期348-350,共3页
根据氯雷他啶系列药物中间体生产废水产生源分析,生产废水中主要污染因子COD浓度约为2 700 mg/L,并含有难以生化降解的苯环、大分子有机物及无机盐等。针对废水这一特点,提出了采用水解酸化-接触氧化-沉淀-气浮法治理后,废水可以达到DB2... 根据氯雷他啶系列药物中间体生产废水产生源分析,生产废水中主要污染因子COD浓度约为2 700 mg/L,并含有难以生化降解的苯环、大分子有机物及无机盐等。针对废水这一特点,提出了采用水解酸化-接触氧化-沉淀-气浮法治理后,废水可以达到DB21-60-89《辽宁省污水与废气排放标准》要求。结果表明,该治理工艺技术可行,经济合理,可实现氯雷他啶系列药物中间体生产废水达标排放,具有良好的社会效益和环境效益,适用于氯雷他啶系列药物中间体生产废水治理。 展开更多
关键词 废水 水解酸化-接触氧化-沉淀-气浮 排放达标
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