Co/Fe催化剂乙醇裂解和部分氧化制氢研究

采用共沉淀法制备的Co/Fe催化剂催化乙醇裂解和部分氧化制氢反应，考察了反应温度对两种途径反应的影响。结果发现，Co/Fe催化剂对乙醇部分氧化制氢显示出较高的氢选择性，且稳定性较好；该催化剂对乙醇裂解制氢也具有较高的氢选择性，但其稳定性很很差。XRD表征结果表明，在催化乙醇部分氧化反应后，Co70Fe30催化剂中存在CoFe合金和CoO相；而催化乙醇裂解反应后，Co70Fe30催化剂中仅存在CoFe合金，即CoFe合金可能是裂解反应的活性组分。     

Ni-Fe催化剂乙醇部分氧化制氢的研究

研究了Ni Fe催化剂对乙醇部分氧化制氢反应,系统地考察了不同O2/C2H5OH摩尔比及反应温度下催化剂的性能.发现Ni Fe催化剂对乙醇部分氧化制氢具有较好的催化活性,其中组成为Ni50Fe50催化剂最好,最佳的反应条件是O2/C2H5OH=1.0,T=573 K.XRD谱图表明催化剂主要由尖晶石结构的铁酸盐和FeNi3合金相组成. XPS结果说明,催化剂体相以还原态FeNi3合金相为主,表面以氧化态的铁酸盐为主.稳定性考察的结果表明,催化剂经40 h反应后,对氢的选择性明显下降,此时对应的FeNi3物相衍射峰强度也明显降低,表明催化剂对H2选择性的下降与FeNi3物相的转变有关.     

Rh/CeO2-SiC催化乙醇部分氧化制氢

设计合成了Rh/CeO2-SiC新型催化剂,X射线衍射和透射电镜等表征结果表明,SiC表面均匀分散了4nm左右的CeO2纳米颗粒,进而可很好地分散Rh纳米粒子.该催化剂在乙醇部分氧化制氢反应中显示出优越的催化性能,乙醇转化率及H2选择性随反应温度的提高而提高,700oC时乙醇转化率为100%,H2选择性为50%,CO选择性仅为13%,且反应40h未见明显失活,反应后催化剂表面没有明显的积炭生成.该催化剂上较低的CO选择性及抗积炭性能可归因于SiC的热传导性能以及CeO2中活泼晶格氧的作用.     

CoFe_2O_4纳米阵列催化剂的费托合成性能研究（英文）

通过可控的水热生长方法和钴铁碳酸根氢氧根水合物的焙烧在泡沫铁上制备了CoFe_2O_4纳米阵列催化剂。通过粉末X射线衍射,扫描电镜和电感耦合等离子体发射光谱表征了CoFe_2O_4纳米阵列的晶相,结构和组成。制备的催化剂被用于费托合成性能研究。CoFe_2O_4纳米阵列催化剂在5 L/(g·h)的空速下具有69%的转化率,并且其性能优于粉体催化剂。     

废水中偏二甲肼在Ni/Fe催化剂上的催化分解研究

研究了Ni/Fe催化剂对废水中偏二甲肼臭氧化分解的催化作用,考察了组分含量、体系的pH值和偏二甲肼初始浓度对催化反应的影响.结果表明,Ni/Fe催化剂对水中偏二甲肼的臭氧化具有良好的催化活性.催化剂组分含量、体系的pH值和初始浓度对反应的影响程度不大.对催化剂的XRD表征结果表明,催化剂主要由尖晶石结构的铁酸盐和FeNi3合金相组成,催化剂的良好催化性能与催化剂中尖晶石结构的铁酸盐和FeNi3合金相的形成有关.     

Pt/Co_3O_4/3DOM Al_2O_3:甲苯燃烧的高效催化剂（英文）

与硫氧化物、氮氧化物、一氧化碳以及悬浮颗粒一样,大部分挥发性有机物(VOCs)污染大气环境.控制VOCs排放有多种方法,其中催化氧化法是一种有效技术,关键在于获得高效催化剂.近年来,负载过渡金属和贵金属催化剂因具有比单纯负载贵金属和单纯负载过渡金属氧化物更好的催化性能而备受关注.在负载贵金属催化剂中,高比表面积载体负载Pt,Pd或Rh催化剂得到广泛而深入的研究,尽管这些催化剂成本较高,但是其对VOCs氧化反应显示了很高的低温催化活性.众所周知,催化活性取决于贵金属和VOCs的种类,不同负载贵金属催化剂对特定反应会表现出不同的催化活性.负载Pt催化剂对长链碳氢化合物和芳香族化合物氧化反应表现出更高的活性.相对于负载贵金属催化剂,负载过渡金属氧化物催化剂不仅具有良好的氧化活性,而且价格低廉.迄今已发现许多过渡金属氧化物(如Co_3O_4,Cr_2O_3和MnO_2等)对典型VOCs氧化反应具有催化活性,其中Co_3O_4的催化活性尤为突出.研究表明,Co_3O_4的性质和分散度是决定其性能的关键因素,制备方法、载体性质和过渡金属氧化物负载量对Co_3O_4的物化性质具有重要影响,而且在负载Pt催化剂中添加金属氧化物能改善其催化性能.尽管多孔氧化铝是一种常用的载体材料,但目前尚无文献报道三维有序大孔-介孔氧化铝负载Co_3O_4和Pt纳米粒子催化剂的制备及其对甲苯氧化反应的催化性能.本文采用聚甲基丙烯酸甲酯微球胶晶模板法、等体积浸渍法和聚乙烯醇保护的硼氢化钠还原法制备了三维有序大孔-介孔(3DOM Al_2O_3)负载Co_3O_4和Pt(xP t/yCo_3O_4/3DOM Al_2O_3,Pt的质量分数(x%)为0-1.4%,Co_3O_4的质量分数(y%)为0-9.2%)纳米催化剂.通过电感耦合等离子体原子发射光谱、X射线衍射、氮气吸附-脱附、扫描电子显微镜、透射电子显微镜、选区电子衍射、X射线光电子能谱及氢气程序升温还原等技术表征了催化剂的物化性质,利用固定床微型石英反应器评价了催化剂对甲苯氧化反应的催化活性.结果表明,xP t/yC o3O4/3DOM Al_2O_3催化剂具有多级孔结构(大孔孔径为180–200 nm,介孔孔径为4–6 nm),比表面积为94-102 m2/g.粒径为18.3 nm的Co_3O_4纳米粒子和粒径为2.3-2.5 nm的Pt纳米粒子均匀分散在3DOM Al_2O_3表面.在xP t/y Co_3O_4/3DOM Al_2O_3催化剂中,1.3Pt/8.9Co_3O_4/3DOM Al_2O_3拥有最高的Oads浓度、最好的低温还原性和最高的甲苯氧化反应催化活性(当空速为20000 mL g~(-1) h~(-1)时,甲苯转化率达90%的反应温度为160 oC).基于催化剂的活性数据和结构表征,我们认为,1.3Pt/8.9Co_3O_4/3DOM Al_2O_3优异的催化性能与其高分散的Pt纳米粒子、高的Oads浓度、好的低温还原性、Pt和Co_3O_4纳米粒子间的强相互作用以及多级孔结构相关.     

Cu/Zn、Cu/Zn/Ni催化剂甲醇部分氧化制氢

研究了甲醇在Cu/Zn及Cu/Zn/Ni催化剂上部分氧化热耦合裂解制氢的反应,系 统地考察了不同O2/CH3OH比及反应温度下催化剂性能.当O2/CH3OH=0.2时,催化剂的性能最 佳.在同样条件下, Cu/Zn催化剂对CO的选择性较Cu/Zn/Ni催化剂低,更具优势. Cu/Zn催化 剂用于甲醇部分氧化反应时,甲醇转化率在150 h寿命实验中基本保持在90％左右. XRD谱图 表明Cu/Zn合金的生成是导致Cu/Zn系催化剂在甲醇裂解反应中快速失活的主要原因,而在部 分氧化反应中, O2的存在可抑制Cu/Zn合金的生成,使Cu/Zn催化剂表现出高度的稳定性.     

含锌尖晶石型ZnM_2O_4(M=Cr,Al,Fe)催化剂上二氯甲烷高效催化燃烧

采用溶胶凝胶法制备出一系列的含锌尖晶石型ZnM_2O_4(M=Cr,Al,Fe)催化剂并测试其对二氯甲烷催化燃烧性能,并对催化剂进行了XRD,H_2-TPR,NH_3-TPD和XPS等表征.制备出的催化剂都具有较高的反应活性,其中ZnCr_2O_4尖晶石活性最佳,其T50为277℃.表征结果表明,催化剂的性能受到表面酸性和氧化还原性的协同作用.ZnCr_2O_4尖晶石催化剂具有较小的中等酸强度的表面酸性和最佳的低温还原性能,因此反应性能最佳.     

有序介孔CuFe2O4同时催化去除碳烟与NOx

采用纳米复刻(浇筑)法制备一系列介孔CuFe_2O_4.通过X射线衍射(XRD)、 N_2物理吸附、透射电镜(TEM)等研究了不同制备条件对有序介孔CuFe_2O_4结构形成的影响.研究发现,作为对比,柠檬酸法仅能合成普通的四方相CuFe_2O_4纳米颗粒,但是硬模板法则能合成出高温淬火才能形成的立方晶相介孔结构CuFe_2O_4.进一步研究了该催化剂同时催化去除碳烟和氮氧化合物(NO_x)的性能,研究发现,与柠檬酸法合成的普通CuFe_2O_4催化剂相比,介孔结构CuFe_2O_4不仅大幅降低了碳烟起燃温度(324降低到278℃),而且将N_2的最高产率从5.9%提升到了92.2%.基于原位漫反射红外(in-situ DRIFTS)的机理分析研究表明,合成过程中采用NaOH除去硬模板的过程中会在介孔CuFe_2O_4表面造成大量残留的钠盐,这种高分散的钠物种促进了NO_x的吸附并转化为硝酸盐物种,从而促进碳烟氧化以及NO_x转化.但是与表面Na修饰的CuFe_2O_4相比,体相Na掺杂的CuFe_2O_4虽然具有更好的有序介孔结构,但是其氧化性能下降,进一步也导致了NO_x的催化还原性能的下降.     

尖晶石型CoCr_2O_4催化剂上二氯甲烷高效催化燃烧

采用共沉淀法在不同焙烧温度下制备一系列尖晶石型CoCr_2O_4催化剂并测试其对CH_2Cl_2催化燃烧性能.制备的催化剂都具有高的反应活性,并发现其性能受到表面酸性和氧化还原性的协同作用.经600℃焙烧的CoCr_2O_4-6催化剂因其具有较高的表面酸量(0.46 mmol·gcat~(-1))和较高表面吸附氧浓度(O_(ads)/O_(lat)=0.55),因此活性最佳,其T_(50)为201℃,T_(90)为278℃.由XRD等结构表征可知该催化剂含CoCr_2O_4和Cr_2O_3两相,但CoCr_2O_4尖晶石是该催化剂的主要活性组分.     

Synthesis,characterization, and application of CoFe2O4@TRIS@sulfated boric acid nanocatalyst for the synthesis of 2-amino-3-cyanopyridine derivatives

Research on Chemical Intermediates - The aim of this research is the synthesis of a novel acidic nanocatalyst using the layer-by-layer assembly technique. The CoFe2O4@TRIS@sulfated boric acid...     

可磁性回收钴-铁酸盐纳米颗粒负载12-钨磷酸催化剂上硫选择性氧化及模型油氧化脱硫（英文）

Silica-coated CoFe2O4 nanoparticles were prepared and used as a support for the immobilization of 12-tungstophosphoric acid, to produce a new magnetically separable catalyst. This catalyst was characterized using X-ray diffraction, wavelength-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, laser particle size analysis, and vibrating sample magnetometry. The catalyst showed high activity in the selective oxidation of thioethers and thiophenes to the corresponding sulfones under mild conditions. The catalytic activity of the nanocatalyst in the oxidative desulfurization of model oil was investigated. The effect of nitrogen-containing compounds on sulfur removal from the model oil was also evaluated. The catalyst showed high activity in the oxidative desulfurization of diesel. The catalyst can be readily isolated from the oxidation system using an external magnet and no obvious loss of activity was observed when the catalyst was reused in four consecutive runs.     

Selective oxidation of sulfurs and oxidation desulfurization of model oil by 12-tungstophosphoric acid on cobalt-ferrite nanoparticles as magnetically recoverable catalyst

Silica-coated CoFe2O4 nanoparticles were prepared and used as a support for the immobilization of 12-tungstophosphoric acid, to produce a new magnetically separable catalyst. This catalyst was characterized using X-ray diffraction, wavelength-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, laser par-ticle size analysis, and vibrating sample magnetometry. The catalyst showed high activity in the selective oxidation of thioethers and thiophenes to the corresponding sulfones under mild condi-tions. The catalytic activity of the nanocatalyst in the oxidative desulfurization of model oil was investigated. The effect of nitrogen-containing compounds on sulfur removal from the model oil was also evaluated. The catalyst showed high activity in the oxidative desulfurization of diesel. The cata-lyst can be readily isolated from the oxidation system using an external magnet and no obvious loss of activity was observed when the catalyst was reused in four consecutive runs.     

The effective peroxidase-like activity of chitosan-functionalized CoFe2O4 nanoparticles for chemiluminescence sensing of hydrogen peroxide and glucose

Here, we report a highly simple and general protocol for functionalization of the CoFe(2)O(4) NPs with chitosan polymers in order to make CoFe(2)O(4) NPs disperse and stable in solution. The functionalized CoFe(2)O(4) NPs (denoted as CF-CoFe(2)O(4) NPs) were characterized by scanning electron microscope (SEM), thermogravimetric (TG), X-ray diffraction (XRD) and FT-IR spectra. It was found that the CoFe(2)O(4) NPs were successfully decorated and uniformly dispersed on the surface of chitosan without agglomeration. The CF-CoFe(2)O(4) NPs were found to increase greatly the radiation emitted during the CL oxidation of luminol by hydrogen peroxide. Results of ESR spin-trapping experiments demonstrated that the CF-CoFe(2)O(4) NPs showed catalytic ability to H(2)O(2) decomposition into ˙OH radicals. On this basis, a highly sensitive and rapid chemiluminescent method was developed for hydrogen peroxide in water samples and glucose in blood samples. Under optimum conditions, the proposed method allowed the detection of H(2)O(2) in the range of 1.0 × 10(-9) to 4.0 × 10(-6) M and glucose in the range of 5.0 × 10(-8) to 1.0 × 10(-5) M with detectable H(2)O(2) as low as 500 pM and glucose as low as 10 nM, respectively. This proposed method has been successfully applied to detect H(2)O(2) in environmental water samples and glucose in serum samples with good accuracy and precision.     

CoFe2O4纳米粉体的聚丙烯酰胺凝胶法合成、表征及磁特性

采用改进的聚丙烯酰胺凝胶法制备了CoFe2O4纳米粉体.利用TG-DSC、mR及XRD等多种手段研究了干凝胶的热分解及CoFe2O4的成相过程.实验表明,以EDTA为配位剂,在500℃的烧结温度下可制备出高纯的CoFe2O4纳米粉体.同时发现.通过改变双丙烯酰胺与丙烯酰胺的比例,可以调控粉体的晶粒尺寸;随着双丙烯酰胺比...     

Heterogenization of a molybdenum Schiff base complex as a magnetic nanocatalyst: An eco-friendly,efficient, selective and recyclable nanocatalyst for the oxidation of alkenes

A Schiff base ligand derived from 5-bromo-2-hydroxybenzaldehyde and 2,2′-dimethylpropylenediamine (H₂L) and its corresponding dioxomolybdenum(VI) complex (Mo(O)₂L) has been synthesized and characterized by spectroscopic methods. The adsorption of Mo(O)₂L on the surface of silica-coated magnetite nanoparticles via hydrogen bonding led to the formation of (α-Fe₂O₃)–MCM-41–Mo(O)₂L as a heterogeneous catalyst. FT-IR and atomic absorption spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize and investigate the new nanocatalyst. A practical catalytic method for the efficient and highly selective oxidation of a wide range of olefins with hydrogen peroxide and tert-butyl hydroperoxide in ethanol over the prepared molybdenum nanocatalyst was investigated. Under reflux conditions, the oxidation of cyclooctene with tert-butyl hydroperoxide or hydrogen peroxide led to the formation of epoxide as the sole product. The catalyst was reused at least six times without a significant decrease in catalytic activity or selectivity, and without detectable leaching of the catalyst.     

Facile synthesis of hierarchical core-shell Fe3O4@MgAl-LDH@Au as magnetically recyclable catalysts for catalytic oxidation of alcohols

A novel core-shell structural Fe(3)O(4)@MgAl-LDH@Au nanocatalyst was simply synthesized via supporting Au nanoparticles on the MgAl-LDH surface of Fe(3)O(4)@MgAl-LDH nanospheres. The catalyst exhibited excellent activity for the oxidation of 1-phenylethanol, and can be effectively recovered by using an external magnetic field.     

钴负载的凹凸棒土催化剂的制备、表征及其催化氧化性能

利用浸渍法制备了一系列不同钴含量的凹凸棒土催化剂,使用X射线衍射(XRD),X射线光电子能谱(XPS)和红外光谱(IR),详细研究了催化剂的构效关系,结果表明钴和载体发生作用形成了CoAl2O4和CoFe2O4两种晶相.研究了催化剂在无溶剂条件下对环己烯的催化氧化性能,实验结果表明Co-AT-1(钴含量0.46%)催化剂对环己烯氧化表现出较好的催化活性.催化剂的有效活性成分是CoFe2O4.     

Correlation between spin-orbital coupling and the superparamagnetic properties in magnetite and cobalt ferrite spinel nanocrystals

The superparamagnetic properties of CoFe2O4 and Fe3O4 nanocrystals have been systematically investigated. The observed blocking temperature of CoFe2O4 nanocrystals is at least 100 deg higher than that of the same sized Fe3O4 nanocrystals. The coercivity of CoFe2O4 nanocrystals at 5 K is over 50 times higher than the same sized Fe3O4 nanocrystals. The drastic difference in superparamagnetic properties between the similar sized spherical CoFe2O4 and Fe3O4 (or FeFe2O4) spinel ferrite nanocrystals was correlated to the coupling strength between electron spin and orbital angular momentum (L-S) in magnetic cations. Compared to the Fe2+ ion, the effect of much stronger spin-orbital coupling at Co2+ lattice sites leads to a higher magnetic anisotropy and results in the dramatic discrepancy of superparamagnetic properties between CoFe2O4 and Fe3O4 nanocrystals. These results provide some insight to the fundamental understanding of the quantum origin of superparamagnetic properties. Furthermore, they suggest that it is possible to control the superparamagnetic properties through magnetic coupling at the atomic level in spinel ferrite nanocrystals for various applications.