Solid state synthesis and characterization of iron（Ⅱ） pyrophosphate Fe2P2O7

Offwhite pure Fe_2P_2O_7 was synthesized through solid phase reaction using Fe_2O_3 and NH_4H_2PO_4 in argon atmosphere.The reaction products of Fe_2O_3 and NH4_H_2PO_4 at a series of temperatures from 400 to 900℃were characterized by XRD.Comparison and analysis of XRD patterns of resultant products indicated well-crystallized Fe_2P_2O_7 could be obtained over 630℃and Fe_2P_2O_7 prepared at 700℃was triclinic in cell type.Comparison of the cell parameters proved that the as-prepared Fe_2P_2O_7 belonged toβ- Fe_2P_2O_7 in crystal phase and SEM showed its size distribution was 0.5-2μm.     

Fe3O4@PI催化剂的制备及其费托合成性能

分别采用水热、水热-包覆、球磨法制备了Fe_3O_4、聚酰亚胺(PI)改性的Fe_3O_4@PI和Fe_3O_4-PI催化剂用于费托合成反应,对比研究了PI改性及其含量变化对Fe基催化剂催化CO加氢产物分布的影响规律。结合XRD、SEM、TEM、H_2-TPR、COTPD、FT-IR、XPS、TG和接触角实验等手段对催化剂样品进行了表征。结果表明,Fe_3O_4、Fe_3O_4@PI和Fe_3O_4-PI样品均为球形颗粒; PI改性促进了Fe_3O_4的还原,亲水性增强。Fe_3O_4@PI样品中,PI均匀包覆于Fe_3O_4表面,具有较好的热稳定性;与Fe_3O_4、Fe_3O_4-PI相比,Fe_3O_4@PI样品CO吸附增强。在CO加氢反应中,与Fe_3O_4相比,PI改性的Fe_3O_4@PI和Fe_3O_4-PI样品催化活性下降,二次加氢能力受到抑制,烯烃选择性提高; Fe_3O_4@PI样品烯烃选择性增加明显,烯烷比(O/P)由改性前的0.50提高至2.15;适宜含量的PI改性促进C5+烃生成。     

Fe2O3/Al2O3氧载体用于甲烷化学链燃烧：负载量与制备方法的影响

以不同方法制备了系列Fe₂O₃/Al₂O₃氧载体,采用XRD、H₂-TPR、CH₄-TPR、O₂-TPD和BET等分析技术对氧载体进行了表征。研究了不同Fe₂O₃负载量氧载体的甲烷化学链燃烧性能,考察了不同制备方法对Fe₂O₃/Al₂O₃氧载体结构、反应性和产物选择性的影响。结果表明,Fe₂O₃负载量对氧载体活性及产物中CO₂选择性的影响较大,负载量较低时氧载体活性较低且引起甲烷部分氧化产物CO含量增加。制备方法亦对氧载体与甲烷的反应活性有所影响,整体上共沉淀法制备的质量分数60％Fe₂O₃/Al₂O₃氧载体具有较高的氧化活性和化学链循环稳定性。其在反应温度850℃、反应时间15 min、30次循环后甲烷转化率及产物中CO₂选择性均未见明显降低。     

Mo/Fe3O4(111)表面对燃煤烟气汞吸附的密度泛函研究

利用CASTEP软件包采用密度泛函理论计算研究了过渡金属Mo掺杂Fe_3O_4(111)Fe_(tet)表面对Hg~0、HgCl和HgCl_2的吸附特征,分析了Mo掺杂前后Fe_3O_4(111)Fe_(tet)表面上不同汞物种的吸附形态。结果表明,Mo掺杂Fe_3O_4(111)Fe_(tet)表面对HgCl和HgCl_2为化学吸附,而对Hg~0的吸附为物理吸附;与纯净表面相比,HgCl在Mo原子掺杂表面上的吸附能提高了40%-66%。HgCl_2在纯净Fe_3O_4(111)Fe_(tet)表面形成"M"形结构;而掺杂Mo原子后,由于Cl原子与Mo原子之间更强的相互作用,使得HgCl_2发生了完全解离,两个Cl原子分别与Mo原子和Fe原子成键吸附在表面,Hg脱附。相关研究结果可为脱除燃煤烟气中的汞提供一定的理论指导。     

SO_4~(2-)功能化处理对Fe_2O_3催化剂上氨选择性催化还原NO_x性能的促进机理研究

采用沉淀法制备了Fe(OH)_3和Fe_2O_3。通过硫酸化处理得到SO_4~(2-)/Fe(OH)_3和SO_4~(2-)/Fe_2O_3两种催化剂,并将其应用于氨选择性催化还原NO_x(NH_3-SCR)反应,研究了SO_4~(2-)功能化处理对Fe_2O_3催化剂上NH_3-SCR脱硝性能的促进机理。结果表明,与纯的Fe_2O_3相比,硫酸化处理得到的催化剂上SCR活性得到显著提升;其中,SO_4~(2-)/Fe(OH)_3表现出更加优异的催化性能,在250-450℃时NO_x转化率高于80%,且具有优异的稳定性和抗H_2O+SO_2性能。XRD、Raman、TG、FT-IR、H_2-TPR、NH_3-TPD和in situ DRIFTS等表征结果显示,硫酸功能化处理能抑制Fe_2O_3的晶粒生长,同时SO_4~(2-)与Fe~(3+)结合形成硫酸盐复合物,提高了催化剂表面酸性位点的数量和酸强度,抑制了Fe_2O_3上的氨氧化反应,从而提高了其脱硝催化性能。     

Pt/Au/Fe3O4的制备及其电化学性能

以制得的纳米Fe₃O₄颗粒作为载体,用还原法将还原出的Au与Pt分别负载到Fe₃O₄颗粒表面,制得纳米Pt/Au/Fe₃O₄复合材料。对Pt/Au/Fe₃O₄进行紫外可见光吸收光谱、透射电子显微镜、X射线衍射及光电子能谱等物理表征,结果表明,Au与Pt均匀地沉积到了Fe₃O₄纳米颗粒表面。对纳米Pt/Au/Fe₃O₄复合材料进行循环伏安扫描,当H₂PtCl₆的加入量达到8 mL时,Pt/Au/Fe₃O₄催化性能最佳;正扫电流峰i_p与扫描速率的平方根v^1/2线性相关,Pt/Au/Fe₃O₄催化氧化甲醇的过程受扩散控制;对催化剂进行201次循环伏安扫描,催化剂仍然能保持较好的催化性能且稳定性良好。因此,所合成催化剂Pt/Au/Fe₃O₄是一种具有良好化学稳定性的阳极催化剂材料。     

复合磁性MgAl水滑石制备及其酯交换性能的研究

使用共沉淀法制备磁性Fe_3O_4粒子,并以此为原料制备出Fe_3O_4/M g Al-LDH,将其焙烧产物Fe_3O_4/M g(Al)O作为微藻油脂和甲醇发生酯交换反应的催化剂,利用产物生物柴油产率作为评价催化剂的活性指标,探究其酯交换活性。通过TGDTG、XRD、SEM、EDS、TEM、N2吸附-脱附、VSM等表征手段对所制备样品进行表征。结果表明,Mg Al-LDH、Mg(Al)O在Fe_3O_4表面生长,并具有一定的磁响应能力。在反应时间为4 h、醇油物质的量比为13∶1的条件下,生物柴油产率高达90%。经过三次使用后,仍具有一定活性。在外磁场的作用下可完成催化剂与反应物的分离。     

化学链制氢中Fe2O3/LaFeO3载氧体的性能研究

采用柠檬酸络合法制备Fe₂O₃/LaFeO₃复合氧化物,将该氧化物作为化学链制氢过程的载氧体,在反应温度为900 ℃、常压下,对Fe₂O₃/CH₄（剂烷比）、进水量、金属负载量进行了考察。结果表明,剂烷比为2：1、进水量为0.1 mL、质量分数15%Fe时载氧体性能最好,甲烷转化率达到60%,单次循环氢气产量为45 mL。将该评价结果与XRD和H₂-TPR表征结果进行关联发现,反应过程的活性位不是金属氧化物,而是吸附氧,而且吸附氧越容易还原,甲烷转化率和氢气产量越高。通过连续60次还原-氧化循环发现,该载氧体上甲烷转化率和氢气产量比较稳定,循环后仍然保持钙钛矿结构。     

A highly selective magnetic sensor with functionalized Fe/Fe3O4 nanoparticles for detection of Pb2+

A magnetic sensor for detection of Pb~(2+) has been developed based on Fe/Fe_3O_4 nanoparticles modified by3-(3,4-dihydroxyphenyl)propionic acid(DHCA). The carboxyl groups of DHCA have a strong affinity to coordination behavior of Pb~(2+) thus inducing the transformation of Fe/Fe_3O_4 nanoparticles from a dispersed to an aggregated state with a corresponding decrease, then increase in transverse relaxation time(T_2) of the surrounding water protons. Upon addition of the different concentrations of Pb~(2+) to an aq. solution of DHCA functionalized Fe/Fe_3O_4 nanoparticles(DHCA-Fe/Fe_3O_4 NPs)([Fe] = 90 mmol/L), the change of T_2 values display a good linear relationship with the concentration of Pb~(2+) from 40 μmol/L to 100 μmol/L and from 130 μmol/L to 200 μmol/L, respectively. Owing to the especially strong interaction between DHCA and Pb~(2+), DHCA-Fe/Fe_3O_4 NPs exhibited a high selectivity over other metal ions.     

三维有序大孔Fe2O3为载氧体的生物质热解气化实验研究

采用无皂乳液聚合法制备单分散聚苯乙烯(PS)微球,并以硝酸盐为原料、柠檬酸为络合剂制备前驱体溶液,通过浸渍和焙烧得到三维有序大孔(3DOM) Fe₂O₃,并通过SEM、XRD、BET和压汞仪对3DOM Fe₂O₃进行表征。采用热重-质谱联用的方法,以3DOM Fe₂O₃为载氧体,对生物质在氦气气氛下的热解气化进行研究,探讨3DOM Fe₂O₃载氧体在生物质热解气化过程中代替纯氧、富氧空气或水蒸气作为生物质气化剂的可能性,并与普通分析纯Fe₂O₃与生物质热解气化的实验结果进行对比,分析3DOM Fe₂O₃在提高载氧体反应活性方面的作用。结果表明,制备的3DOM Fe₂O₃呈现排列规整的三维有序多孔形貌,层与层间通过三维孔道相连,并呈交替排列。通过与分析纯Fe₂O₃的XRD谱图对比,发现制得的3DOM Fe₂O₃为纯Fe₂O₃,无其他杂质相的存在。热重-质谱分析结果表明,Fe₂O₃作为载氧体在高温段促成了生物质气化反应的发生。与分析纯的Fe₂O₃作对比,当载氧体为三维有序大孔结构时,生物质的最大失重率提高了7.1%,气化阶段的最大失重速率提高了0.29%/min,CO、CO₂、CH₄在高温段出现两个连续的析出峰。     

溶剂热法制备四氧化三铁/聚乙烯亚胺修饰的多壁碳纳米管复合粒子及其吸波性能

采用溶剂热法将磁性Fe_3O_4粒子附着在聚乙烯亚胺(PEI)修饰的多壁碳纳米管(MWNTs)表面,制备了兼具介电损耗和磁损耗的复合吸波微粒Fe_3O_4/MWNTs。利用X射线衍射仪(XRD)、傅里叶红外光谱仪(FTIR)、热重分析仪(TGA)、透射电子显微镜(TEM)及矢量网络分析仪等分析了Fe_3O_4/MWNTs复合粒子的结构、形貌和吸波性能。TEM结果表明,由于PEI的修饰作用,Fe_3O_4/MWNTs复合粒子具有良好的分散性。XRD结果显示,附着的Fe_3O_4粒子具有完整的晶型结构。吸波性能结果表明,PEI修饰的Fe_3O_4/MWNTs复合微粒拥有非常优异的吸波性能,随着厚度的增加,复合微粒的吸收峰向低频处移动。在厚度为3.2 mm,频率为6.16 GHz时,出现了最大反射损耗-42.9 d B,反射损耗大于-10 d B的频段为1.42 GHz(5.40~6.82 GHz)。     

Fast synthesis of dopamine-coated Fe3O4 nanoparticles through ligand-exchange method

A fast approach was described for the synthesis of water-dispersible monodisperse dopamine-coated Fe₃O₄ nanoparticles（DA-Fe₃O₄） with uniform size and shape via ligand-exchange of oleic acid on Fe₃O₄ using only 2 min.The prepared DA-Fe₃O₄ nanoparticles were characterized by transmission electron microscopy,Fourier transform infrared spectrometry,and vibrating sample magnetometer.The results indicated that the resulting DA-Fe₃O₄ nanoparticles had an average diameter of about 19.2 nm. The magnetic saturation value of the prepared DA-Fe₃O₄ nanoparticles was determined to be 72.87 emu/g,which indicating a well-established superparamagnetic property.     

基于Fe_3O_4/乙二胺四乙酸磁性粒子的集成化蛋白质组学方法

建立了基于Fe_3O_4/乙二胺四乙酸(EDTA)磁性粒子的集成化蛋白质组学研究方法。首先用共沉淀法合成EDTA负载的Fe_3O_4/EDTA磁性粒子。在优化的溶液条件下(95%乙腈-1%三氟乙酸,体积分数),100μg Fe_3O_4/EDTA磁性粒子可吸附12.4μg牛血清白蛋白(BSA),吸附容量是商品化磁珠的10倍左右。以BSA作为标准蛋白质,对所合成的Fe_3O_4/EDTA磁性粒子作为蛋白质组学反应器的酶解时间进行了优化,发现Fe_3O_4/EDTA磁性粒子处理BSA酶解1、8和16 h的肽段序列覆盖率和特征肽段结果相当。因此,可以将复杂的蛋白质样品前处理时间缩短至2 h内。最后,将所合成的Fe_3O_4/EDTA磁性粒子应用于血清的蛋白质组学研究,成功地鉴定出218种蛋白质,其中包含了41种美国食品药品管理局(FDA)认证的生物标志物。所发展的基于Fe_3O_4/EDTA磁性粒子的蛋白质组学样品前处理方法将蛋白质样品预富集、还原、烷基化、酶解、多肽除盐和洗脱等步骤集成到一起,减少了样品转移和处理所造成的损失。这种技术具有快速、灵敏和易于操作的特点,可用于临床蛋白质组学研究。     

Thermal solid–solid interactions and physicochemical properties of NiO/Fe2O3 system doped with K2O

The effects of calcination temperature and doping with K₂O on solid–solid interactions and physicochemical properties of NiO/Fe₂O₃ system were investigated using TG, DTA and XRD techniques. The amounts of potassium, expressed as mol% K₂O were 0.62, 1.23, 2.44 and 4.26. The pure and variously doped mixed solids were thermally treated at 300, 500, 750, 900 and 1000 °C. The catalytic activity was determined for each solid in H₂O₂ decomposition reaction at 30–50 °C. The results obtained showed that the doping process much affected the degree of crystallinity of both NiO and Fe₂O₃ phases detected for all solids calcined at 300 and 500 °C. Fe₂O₃ interacted readily with NiO at temperature starting from 700 °C producing crystalline NiFe₂O₄ phase. The degree of reaction propagation increased with increasing calcination temperature. The completion of this reaction required a prolonged heating at temperature >900 °C. K₂O-doping stimulates the ferrite formation to an extent proportional to its amount added. The stimulation effect of potassium was evidenced by following up the change in the peak height of certain diffraction lines characteristic NiO, Fe₂O₃, NiFe₂O₄ phases located at “d” spacing 2.08, 2.69 and 2.95 Å, respectively. The change of peak height of the diffraction lines at 2.95 Å as a function of firing temperature of pure and doped mixed solids enabled the calculation of the activation energy (ΔE) of the ferrite formation. The computed ΔE values were 120, 80, 49, 36 and 25 kJ mol⁻¹ for pure and variously doped solids, respectively. The decrease in ΔE value of NiFe₂O₄ formation as a function of dopant added was not only attributed to an effective increase in the mobility of reacting cations but also to the formation of potassium ferrite. The calcination temperature and doping with K₂O much affected the catalytic activity of the system under investigation.     

Photothermal performance of MFe2O4 nanoparticles

In this paper, we synthesized three kinds of ferrites and investigated their photothermal property. The result indicated that the photothermal effect of Fe₃O₄ and MnFe₂O₄ nanoparticles declined while that of ZnFe₂O₄ nanoparticles maintained relatively stable after preservation for 70 days, and then ZnFe₂O₄ nanoparticles could effectively kill cancer cells under NIR laser.     

Diagram of phase equilibria in the Fe2V4O13-WO3 system

A diagram for the phase equilibria established in the two-component Fe₂V₄O₁₃-WO₃ system (one of the intersections of the Fe₂O₃-V₂O₅-WO₃ three-component system) has been constructed based on the measurements made by DTA and X-ray phase analysis. The diagram shows that the system investigated does not appear to be a true two-component system, even below the solidus line.     

Fe_3O_4/RGO复合材料的制备及其电化学性能研究

以改进Hummers法合成的氧化石墨烯(GO)为前驱体,通过水热法结合烧结工艺制备了四氧化三铁/还原氧化石墨烯(Fe_3O_4/RGO)复合材料。利用X射线衍射(XRD)、拉曼光谱(Raman)、扫描电镜(SEM)、透射电镜(TEM)等手段对复合材料的理化性能进行表征;通过充放电测试、循环伏安(CV)和电化学阻抗谱(EIS)等技术,综合考察了材料的储锂性能及电化学性能增强机制。结果表明,在200和600 m A/g电流密度下,Fe_3O_4/RGO复合负极循环60次后的放电比容量分别保持在709和479 mAh/g,表现出良好的倍率性能;相较于纯Fe_3O_4负极,复合负极呈现出更优异的锂电性能,其电化学性能的改善得益于RGO能增强材料的电导性和结构稳定性。     

铈修饰铁基复合载氧体用于化学链甲烷部分氧化重整制合成气研究

以Al₂O₃为惰性载体,利用共沉淀法制备了CeO₂-Fe₂O₃-Al₂O₃复合载氧体,并对载氧体进行了XRD、SEM表征。在固定床反应器中,考察了程序升温、恒温、多循环等操作条件下,载氧体对甲烷部分氧化重整的反应性能。程序升温实验结果表明,在相同温度下,CeO₂含量为30%的载氧体与不含CeO₂的载氧体对比,CH₄转化率、H₂和CO选择性均提高。在恒温实验中,含有CeO₂的两种载氧体,CH₄转化率、H₂和CO选择性上也都明显高于不含CeO₂的载氧体,当反应时间小于1 200 s时,无积炭发生。三种载氧体经过15次循环后,CeO₂含量为30%的载氧体表现出最佳的循环特性。多循环实验中,当反应温度850 ℃、反应时间945 s时,CH₄最大转化率达到91.53%、H₂的最大选择性达到86.36%、CO的最大选择性达到85.12%、H₂与CO的最佳平均物质的量比为2.03。XRD谱图显示,经过多次循环后,三种载氧体的物相没有发生变化,载氧体表现出了很好的稳定性能。     

煤灰/K_2CO_3/Fe_2O_3对脱矿无烟煤燃点与燃烧速率的影响(英文)

考察了煤灰/K2CO3/Fe2O3及其之间的相互作用对酸洗无烟煤燃点和燃烧速率的影响。不同温度下制备的煤灰显示了不一样的性质(如化学组成、颜色和形貌)。脱矿无烟煤(负载和非负载催化剂)的燃烧反应性测试在热重分析仪(TGDTG)中完成,结果表明,煤灰本身对酸洗无烟煤的燃点几乎没有影响,而高温下制备的煤灰能够明显提高酸洗无烟煤的燃烧速率。当煤灰和K2CO3或者Fe2O3的混合物加入酸洗无烟煤中作为燃烧催化剂时,可以看出与单独使用K2CO3或Fe2O3相比,煤灰的加入明显导致酸洗煤的燃烧速率下降,而对其燃点影响不大。同样,K2CO3和Fe2O3之间的相互作用也能够对酸洗无烟煤的燃烧速率产生负面影响。     

Synthesis of Fe2O3 nanowires by oxidation of iron

By carefully controlling the reacting conditions, including atmosphere, temperature, and reacting time, we managed to prepare the nanowires of Fe₂O₃ by oxygenating pure iron. X-ray and transmission electronic microscope analyses demonstrate that the Fe₂O₃ nanowires are of rhombohedral structure, i.e., -Fe₂O₃. It is shown by our study that the -Fe₂O₃ nanowires have a diameter ranging from 15 to 75 nm and their typical lengths are in the range 10–20 μm. Within our knowledge it is the first report on nanowires of Fe₂O₃. The Fe₂O₃ nanowires are expected to present special magnetic, optical and electrical properties, and facilitate future nanoscale device applications.