SO2-4/ZrO2/Fe3O4/Al2O3磁性固体超强酸的制备与表征

用化学共沉淀法制备了一系列SO2-4/ZrO2/Fe3O4/Al2O3磁性固体超强酸, 利用XRD、IR、TG-DSC、VSM、TEM及HRTEM等手段对样品结构进行了表征. 结果表明, 引入一定量的Fe3O4和Al2O3有利于四方晶相ZrO2(t)结构的稳定；Fe3O4超细粒子的引入, 使固体超强酸具备了超顺磁性；HRTEM 结果显示ZrO2晶体生长趋向于ZrO2(t)的[101]方向,其(101)晶面间距为d(101)=0.29 nm, 与XRD 衍射结果一致. Hammett 指示剂测得样品SZA-20-200-800酸强度(H0<-13.8)最强, 酸性大于浓硫酸(H0=-11.9).     

Fe3 O4 /P(NVP-MAA)核壳复合微球的制备与表征

以N-乙烯基吡咯烷酮（NVP）和甲基丙烯酸（MAA）为原料,过硫酸钾为引发剂,采用乳液聚合的方法共聚包埋自制的磁流体Fe3O4,制得了Fe3O4／P（NVP—MAA）核壳复合微球。以粒径,羧基含量,Fe3O4含量为指标,采用L9（3^4）正交表,探讨了反应温度、单体总用量、单体配比和引发剂用量对反应的影响。通过多指标极差分析,确定了制备复合微球的最佳条件。并用IR,TG,SEM及XRD对其结构进行了表征。     

控制自由基聚合制备Fe_3O_4/SiO_2/P(AA-MMA-St)磁性复合微球

用原硅酸乙酯对Fe3O4纳米粒子进行表面改性得到Fe3O4/SiO2磁流体.在Fe3O4/SiO2磁流体存在下,以1,1-二苯基乙烯(DPE)为自由基聚合控制剂,利用乳液聚合法制备了Fe3O4/SiO2/P(AA-MMA-St)核-壳磁性复合微球.用红外光谱(FTIR)、振动样品磁强计(VSM)、透射电镜(TEM)、X光电子能谱(XPS)、热重分析(TGA)、示差扫描量热仪(DSC)对所制备的磁流体、磁性高分子复合微球的结构、形态、性能进行了表征.研究发现,原硅酸乙酯水解后能在Fe3O4表面形成硅膜保护层从而避免Fe3O4的酸蚀,使Fe3O4/SiO2/P(AA-MMA-St)复合微球的比饱和磁化强度比同样条件下制备的Fe3O4/P(AA-MMA-St)微球提高了28%;DPE能有效控制自由基在Fe3O4/SiO2磁流体表面均匀地引发单体聚合,得到平均粒径为422 nm,无机粒子含量为40%,比饱和磁化强度为34.850 emu/g,表面羧基含量为0.176 mmol/g的磁性复合微球.     

Fe_3O_4@Nico@Ag纳米催化剂催化硝基芳烃加氢(英文)

We report the fabrication and characterization of a magnetically recyclable Fe_3O_4@Nico@Ag catalyst for reduction reactions in the liquid phase. Fe_3O_4 is a magnetic core and nicotinic acid was used as the linker for Ag. The characterization was done with X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, vibrating sample magnetometry(VSM), and ultraviolet-visible spectroscopy. VSM measurements proved the superparamagnetic property of the catalyst.     

具有核壳结构磁性复合微球的制备与表征

采用两步法制备了具有核壳结构的Fe3O4/P(MMA/DVB)(core)-P(St/GMA/DVB)(shell)磁性复合微球.首先,用改进的细乳液聚合制备了Fe3O4/P(MMA/DVB)微球;然后,加入总量不同的苯乙烯(St)、甲基丙烯酸缩水甘油酯(GMA)和二乙烯基苯(DVB),通过种子乳液聚合,制备了不同磁含量的核壳结构的磁性复合微球.分别用X-射线衍射(XRD)、高倍透射电镜(HR-TEM)、热重分析(TGA)、振动样品磁力计(VSM)等手段对磁性微球的性能进行了表征.实验结果表明,Fe3O4/P(MMA/DVB)微球的磁含量为84 wt%;通过改变加入壳层单体的量,核壳复合微球的磁含量可控在20 wt%~76 wt%之间.该微球具有超顺磁性,相应的饱和磁化强度为12~50Am2/kg.     

表面引发原子转移自由基聚合方法合成Fe3O4/PMMA复合纳米微粒

采用表面引发原子转移自由基聚合方法合成了核壳结构的磁性高分子纳米微粒. 作为聚合反应引发剂的3-氯丙酸, 首先与油酸修饰的Fe3O4纳米微粒表面的部分油酸置换, 然后在Fe3O4纳米微粒表面引发甲基丙烯酸甲酯聚合, 合成的纳米复合材料用TEM, FTIR, XRD和DSC表征. 磁性测试结果表明, 所制备的磁性高分子纳米微粒仍具有超顺磁性, 但由于聚合物的存在, 其饱和磁化强度降低.     

制备高比表面负载型催化剂的一种新方法

In this paper, a new way to increase the specific surface areas of supported catalysts has been suggested. The results for MoO_3/ZrO_2, WO_3/ZrO_2, CuO/ZrO_2, SO_4~(2-)/ZrO_2, NiO/ZrO_2, Fe_2O_3/ZrO_2, Fe_2(SO_4)_3/ZrO_2, MoO_3/TiO_2, WO_3/TiO_2, SO_4~(2-)/TiO_2, NiSO_4/TiO_2, NiO/TiO_2, V_2O_5/TiO_2 etc. systems show that the specific surface areas of the samples, prepared by impregnating some hydroxides then calcinating at high temperature, are much larger than those of the samples prepared with a traditional method——impregnating their oxides calcinated at the same temperature. Using this way, the specific surface areas of some supported catalysts can increase by several times. The surface areas of some supports such as zirconia and titania are not large enough, and they are easy to sinter at high temperature. In these cases, the advantage of of this preparation method is fully displayed, and the specific surface areas of the resulting zirconia-or titania-supported catalysts can compare favourably with those of the catalysts prepared from some classical supports (such ar γ-Al_2O_3, SiO_2).In addition, it has been proved by means of XPS, XRD, LRS, and DTA that as an active component disperse on a support as a monolayer and its content comes up to its monolayer dispersion capacity, the specific surface area of the obtained catalyst would be the largest. We suggest a mechanism that an active component covered on a support can not only segregate its particles, but also hinder the surface diffusion of support, and as a result, its crystalline growth, an accompanying phase transformation and inter-crystalline sintering are all retarded.     

Fe_3O_4/P(NaUA-St-BA)核-壳纳米磁性复合粒子的合成与表征

以表面包敷有反应型的表面活性剂NaUA(十一烯酸钠)的Fe3O4磁性胶体粒子为种子,运用无皂乳液聚合方法原位制备出Fe3O4P(NaUAStBA)核壳纳米磁性复合粒子.Fe3O4磁性胶体粒子的粒径为10nm左右.IR和TG结果分析表明,苯乙烯、丙烯酸酯和NaUA在Fe3O4粒子的表面发生了聚合反应,形成P(NaUAStBA);TEM和激光粒度分析仪测试结果显示,Fe3O4P(NaUAStBA)复合粒子具有核壳结构而且粒子分布均匀、平均粒径60nm;TG测试的结果表明,NaUA在Fe3O4粒子的包覆率为13.83%,P(NaUAStBA)共聚物的包覆率71.85%;振动样品磁强仪(VSM)测试的磁滞回线则表明由无皂乳液聚合得到的Fe3O4P(NaUAStBA)复合粒子具有超顺磁性,可避免磁性微球在磁场中的团聚.另外,合成的磁性胶乳可稳定存放数月.     

新型双功能磁性纳米催化剂的制备与表征

传统酸性催化反应以稀硫酸为酸催化剂,虽然稀硫酸的催化活性很高,但由于稀硫酸极易腐蚀设备、不易与反应体系分离、易造成环境污染等缺点,如何用固体超强酸取代稀硫酸作为酸催化剂成为了研究的重点.对目前有关磁性固体超强酸的研究主要有SO42-/ZrO2/MFe2O4(M=Fe,Co,N i)[1~3]和     

悬浮聚合法制备磁性分子印迹聚合物微球

以苯胺和二甲基苯胺为模板分子、甲基丙烯酸(MAA)为功能单体、三羟甲基丙烷三丙烯酸酯(TRIM)为交联单体、Fe3O4为磁性组分,采用悬浮聚合法制备了磁性分子印迹聚合物微球(MMIPMs)。结果表明,改性Fe3O4微粒在MMIPMs中分散较好,MMIPMs在水性介质中对模板分子的选择吸附性较差,但在有机介质中有较好的选择吸附性。     

Magnetic core–shell Fe3O4@C-SO3H nanoparticle catalyst for hydrolysis of cellulose

Catalytic hydrolysis of cellulose over solid acid catalysts is one of efficient pathways for the conversion of biomass into fuels and chemicals. High catalytic activity and easy separation from reaction media are two important factors for evaluating the performance of the solid acid catalysts for the cellulose hydrolysis. In this study, we report a core–shell Fe₃O₄@C-SO₃H nanoparticle with a magnetic Fe₃O₄ core encapsulated in a sulfonated carbon shell, as recyclable catalyst for the hydrolysis of cellulose. The sulfonated carbon shell shows a good activity, presenting 48.6 % cellulose conversion with 52.1 % glucose selectivity under the moderate conditions of 140 °C after 12 h reaction. Importantly, the magnetic Fe₃O₄ core makes the catalysts easily separated from reaction mixtures by using the externally applied magnetic field. In addition, the Fe₃O₄@C-SO₃H nanoparticle catalyst shows a high stability in the activity and magnetization during recycling tests, suggesting it a promising solid acid catalyst for the hydrolysis of cellulose.     

Characterization of Fe3O4/P(St-MPEO) Amphiphilic Magnetic Polymer Microspheres

IntroductionMagnetic microspheres have been widely usedin many fields,such as targetdrug,cell separationand enzyme immunoassay,since the past twentyyears because of their relatively rapid and easymagnetic separation[1] .Although a poly(ethyleneoxide) supported- catalyst system with a solublepolymer as the carrier can easily keep the activityand the selectivity of the catalyst,its recovery hasto be performed by filtration or precipitation fromthe reaction medium,which is time- consuming andener…     

Silica-dendrimer core-shell microspheres with encapsulated ultrasmall palladium nanoparticles: efficient and easily recyclable heterogeneous nanocatalysts

We report the synthesis, characterization, and catalytic properties of novel monodisperse SiO(2)@Pd-PAMAM core-shell microspheres containing SiO(2) microsphere cores and PAMAM dendrimer-encapsulated Pd nanoparticle (Pd-PAMAM) shells. First, SiO(2) microspheres, which were prepared by the St?ber method, were functionalized with vinyl groups by grafting their surfaces with vinyltriethoxysilane (VTS). The vinyl groups were then converted into epoxides by using m-chloroperoxybenzoic acid. Upon treatment with amine-terminated G4 poly(amidoamine) (PAMAM) dendrimers, the SiO(2)-supported epoxides underwent ring-opening and gave SiO(2)@PAMAM core-shell microspheres. Pd nanoparticles within the cores of the SiO(2)-supported PAMAM dendrimers were synthesized by letting Pd(II) ions complex with the amine groups in the cores of the dendrimers and then reducing them into Pd(0) with NaBH(4). This produced the SiO(2)@Pd-PAMAM core-shell microspheres. The presence of the different functional groups on the materials was monitored by following the changes in FTIR spectra, elemental analyses, and weight losses on thermogravimetric traces. Transmission electron microscopy (TEM) images showed the presence of Pd nanoparticles with average size of 1.56 ± 0.67 nm on the surface of the monodisperse SiO(2)@Pd-PAMAM core-shell microspheres. The SiO(2)@Pd-PAMAM core-shell microspheres were successfully used as an easily recyclable catalyst for hydrogenation of various olefins, alkynes, keto, and nitro groups, giving ~100% conversion and high turnover numbers (TONs) under 10 bar H(2) pressure, at room temperature and in times ranging from 10 min to 3 h. In addition, the SiO(2)@Pd-PAMAM core-shell microspheres were proven to be recyclable catalysts up to five times with barely any leaching of palladium into the reaction mixture.     

聚丙烯酰胺修饰Fe_3O_4磁性纳米粒子的制备与表征

首先通过化学处理在Fe3O4磁性纳米粒子表面引入Si—H键,然后通过选择性的硅氢加成反应制备了一个端基带溴的磁性引发剂,并利用原子转移自由基聚合(ATRP)技术,在该磁性引发剂表面接枝了聚丙烯酰胺高分子,该聚丙烯酰胺高分子展现出分子量高度可控性和窄的分子量分布.经聚丙烯酰胺修饰后Fe3O4磁性纳米粒子的比饱和磁化强度为58.5 emu.g-1,与未修饰纳米Fe3O4相比下降约20%.     

助剂Cu、K对F-T合成铁基催化剂作用的表征研究

采用连续共沉淀和喷雾干燥技术相结合的方法制备了一组Cu、K助剂单独或同时加入的微球状Fischer-Tropsch（F-T）合成铁基催化剂,借助低温N2吸附、MES、XRD、H2-TPR、CO-TPR研究了Cu和K助剂对催化剂织构、还原性能以及还原和炭化过程中的物相变化的影响。结果表明,K助剂的加入能明显提高催化剂的比表面积和铁物相在催化剂中的分散程度,增加了Fe2O3与SiO2间的相互作用;当催化剂在H2和合成气中还原时,Cu助剂的加入有利于催化剂的还原和Fe3O4的生成,在CO中还原时,Cu助剂的加入则有利于α-Fe的生成和稳定化。在H2和合成气中,单独K助剂的加入会抑制催化剂的还原或炭化,而Cu和K助剂的同时加入在H2、CO和合成气下均可使催化剂的还原或炭化能力明显提高,表明Cu和K助剂间存在一定的协同作用。     

高Fe_3O_4含量单分散P(St/AA)复合微球的合成与表征

在表面由十一烯酸和油酸共同修饰的Fe3O4磁流体存在下,以苯乙烯(St)和丙烯酸(AA)为共聚单体,用细乳液聚合法,制备了单分散,高Fe3O4含量,且表面带有羧基的超顺磁性高分子复合微球.采用透射电镜(TEM),热重分析(TGA),物性测量系统(PPMS),Zeta电位以及红外光谱等手段对磁性复合微球的各项性能进行表征.结果表明,Fe3O4粒子的表面改性是影响复合微球Fe3O4含量及形貌的关键因素.在优化的实验条件下,可以制得Fe3O4含量高达77wt%,平均粒径为137·9nm,表面羧基密度0·0894mmol/g,比饱和磁化强度为44·7emu/g的单分散超顺磁性高分子复合微球.     

PVP-b-PLA修饰Fe_3O_4磁性纳米粒子的制备与表征

通过硅烷偶联剂与Fe3O4磁性纳米粒子偶合在其表面引入C C端基,进一步与N-乙烯基吡咯烷酮(NVP)加成聚合制备含端羟基PVP包裹的磁体,再引发丙交酯(LA)开环聚合制得PVP-b-PLA修饰的Fe3O4纳米粒子.通过XRD、GPC、FTIR、SEM、TG、DSC和激光粒度仪等,对产物进行分析和表征,结果表明,纳米Fe3O4与PVP以及PVP与PLA之间均为化学键联,PVP和PLA是以嵌段共聚物的形式存在且两者之间存在明显的微相分离,纳米Fe3O4表面聚合物包覆率为35%,厚度约13 nm.此外,该PVP-b-PLA包覆的磁性纳米粒子比饱和磁化强度为53 emu/g,与未包覆相比下降约25%.     

氨基两亲高分子磁性微球的制备与表征

采用分散聚合法,以乙醇水为介质,在Fe3O4磁流体存在下,通过苯乙烯与聚氧乙烯大分子单体(MPEO)共聚制备了同时具有两亲性和磁响应性的端基为氨基的高分子微球.改变聚合条件可以得到平均粒径范围在5～80μm,氨基含量为0.01～0.25mmolg的两亲磁性高分子微球.     

1D Fe_3O_4@CuSiO_3 composites catalyzed decarboxylative A~3-coupling for propargylamine synthesis

Highly active and stable magnetic copper catalysts were successfully achieved by magnetic induced Stober method and subsequent hydrothermal reaction with copper ions in alkaline condition.The high content of Cu~(2+) as well as the unique structures of hierarchical copper silicate in the as-prepared catalysts endowed their outstanding catalytic performance.Efficient decarboxylative A~3-coupling of a-keto acid,amine and alkyne was realized with the low Fe_3 O_4@CuSiO_3 loading.A range of propargylamines were produced in good to excellent yields under solvent-free condition.Moreover,the catalyst can be easily separated from the final organic product with an external magnet.Also,this kind of catalyst could be recycled up to six times while maintaining its activity.