The ZnO molecule plays an important role in the industry due to it special features, anti-corrosion anti-bacterial properties, as well as due to its low electrical conductivity and heat resistance. In these experiment...The ZnO molecule plays an important role in the industry due to it special features, anti-corrosion anti-bacterial properties, as well as due to its low electrical conductivity and heat resistance. In these experimental researches, the sol-gel method was chosen, which enables control of nucleation, aging and growth of particles in the solution. ZnO synthesis was prepared utilizing chemical method with Zinc acetate dyhidrate and NaOH with the appropriate methanol solvent and heating (60˚C). The methods used in identification and characterization are FTIR, UV/VIS, OPTICAL MICROSCOPY, SEM and XRD. The FTIR spectra of synthesized ZnO with corresponding ones show characteristic bands at the corresponding wavelengths, which confirm the presence of ZnO nanoparticles. SEM characterization of ZnO shows the morphology of needle-shaped nanoparticles. XRD spectar in this research by chemical method indicates the particle size of 17.76 nm.展开更多
The vapor recompression heat pump(VRHP) distillation technology offers significant improvements in energy efficiency for distillation systems with small temperature differences between the top and bottom of the column...The vapor recompression heat pump(VRHP) distillation technology offers significant improvements in energy efficiency for distillation systems with small temperature differences between the top and bottom of the column. However, the separation of wide-boiling binary mixtures leads to substantial temperature differences between the top and bottom of the column. This limits the applicability of conventional VRHP due to high capital costs and strict performance requirements of the compressor. To overcome these challenges and to accommodate compressor operating conditions, a novel synthesis and design method is introduced to integrate VRHPs with wide-boiling binary mixture distillation columns(WBMDCs). This method enables quick determination of an initial configuration for the integrated WBMDC-VRHP system and helps identify the optimum configuration with the minimum total annual cost. Two examples, namely the separation of benzene/toluene and isopropanol/chlorobenzene, are employed to derive optimum configurations of the WBMDC-VRHP and compare them with the WBMDC. A systematic comparison between the WBMDC-VRHP and WBMDC demonstrates the superior steady-state performance and economic efficiency of the WBMDC-VRHP.展开更多
Focused exploration of earth-abundant and cost-efficient non-noble metal electrocatalysts with superior hydrogen evolution reaction(HER)performance is very important for large-scale and efficient electrolysis of water...Focused exploration of earth-abundant and cost-efficient non-noble metal electrocatalysts with superior hydrogen evolution reaction(HER)performance is very important for large-scale and efficient electrolysis of water.Herein,a sandwich composite structure(designed as MS-Mo2C@NCNS)ofβ-Mo2C hollow nanotubes(HNT)and N-doped carbon nanosheets(NCNS)is designed and prepared using a binary NaCl–KCl molten salt(MS)strategy for HER.The temperature-dominant Kirkendall formation mechanism is tentatively proposed for such a three-dimensional hierarchical framework.Due to its attractive structure and componential synergism,MS-Mo2C@NCNS exposes more effective active sites,confers robust structural stability,and shows significant electrocatalytic activity/stability in HER,with a current density of 10 mA cm-2 and an overpotential of only 98 mV in 1 M KOH.Density functional theory calculations point to the synergistic effect of Mo2C HNT and NCNS,leading to enhanced electronic transport and suitable adsorption free energies of H*(ΔGH*)on the surface of electroactive Mo2C.More significantly,the MS-assisted synthetic methodology here provides an enormous perspective for the commercial development of highly active non-noble metal electrocatalysts toward efficient hydrogen evolution.展开更多
The nitrogen-doped and （metal, nitrogen）-codoped TiO2 photocatalysts （metal = Ag, Ce, Fe, La） were synthesized by sol-gel auto-igniting synthesis （SAS） with the complex compound sol of TiCl4-NH4NO3-citri acid-me...The nitrogen-doped and （metal, nitrogen）-codoped TiO2 photocatalysts （metal = Ag, Ce, Fe, La） were synthesized by sol-gel auto-igniting synthesis （SAS） with the complex compound sol of TiCl4-NH4NO3-citri acid-metal nitrate- NH3.H20 as a precursor. The products were characterized by means of XRD, XPS, and UV-Vis diffuse reflectance spectra, and their photocatalytic activity was investigated under visible light. It was found that all the synthesized powders showed good absorption for visible light, and that the radius and alterable valence states of doping metallic cations played important roles on their photocatalytic activity. These results were discussed in detail.展开更多
（La, N） co-doped TiO2 photocatalysts were synthesized using TiC14 sol-gel autoignidng synthesis （SAS） starting from a complex compound system of TiCl4-La（NO3）3-citric acid-NH4NO3-NHyH2O, in which the （La, N） c...（La, N） co-doped TiO2 photocatalysts were synthesized using TiC14 sol-gel autoignidng synthesis （SAS） starting from a complex compound system of TiCl4-La（NO3）3-citric acid-NH4NO3-NHyH2O, in which the （La, N） co-doped process was accompushed in the formation of TiO2 nanocrystals. The prepared samples were characterized by using X-ray diffraction （XRD）, X-ray photoemission spectroscopy （XPS） and UV-vis diffuse reflectance spectra. The results indicated that nitrogen and lanthanum were incorporated into the lattice and interstices of titania nanocrystals, which resulted in narrowing the band gap and promoting the separation of photoexcited hole-electron pairs, respectively, and showing expected red-shifts and enhanced photocatalytic activity under visible light. The mechanism on nitrogen doping and enhancement in photocatalyfic activity of （La, N） co-doped titania by SAS was discussed in detail.展开更多
Micro/nanostructured SiOx/C composite was firstly synthesized by carbothermal reduction of silica-carbon binary xerogel.The homogeneous dispersion feature of the two components in binary xerogel contributes to effecti...Micro/nanostructured SiOx/C composite was firstly synthesized by carbothermal reduction of silica-carbon binary xerogel.The homogeneous dispersion feature of the two components in binary xerogel contributes to effectively carbothermally reduce the O/Si atomic ratio,enhancing the electrochemical activity of the SiOx component.The micron-sized SiOx/C spheres are composed of many near-spherical nanoparticles.The synthesized SiOx/C exhibits a stable and high reversible capacity of 830 m A·h·g^-1 for 100 cycles,and excellent rate-capability.The homogeneous dispersion structure of phases,the micro/nanostructure and the high electrochemical activity of SiOx component combinedly contribute the excellent electrochemical performance.展开更多
Using hydrous aluminum chloride （AlCl3·6H2O） and silicon ethoxide （Si （OC2H5）4） as raw materials, a kind of nano-sized mullite powder was synthesized with the sol-gel process at the medium calcination tempe...Using hydrous aluminum chloride （AlCl3·6H2O） and silicon ethoxide （Si （OC2H5）4） as raw materials, a kind of nano-sized mullite powder was synthesized with the sol-gel process at the medium calcination temperature. The microstructures of the alumina-silica binary aerogel and calcined nano-sized materials were investigated by means of thermogravimetry-differential thermal analysis （TG-DTA）, scanning electron microscopy （SEM） and X-ray diffractometer （XRD）. The results show that the mullitization of Al2O3-SiO2 in gel starts from about 1 000℃ and its formation ofmullite takes place in the range of 1 100℃-1 250 ℃. The size of the nano-sized mullite powder calcined at 1 250 ℃ is measured to be about 30 nm.展开更多
Nickel molybdate(NiMoO4)nanoparticles(NPs)were synthesized by sol-gel method.Utilizing water as solvent providescrystalline nanostructures.These nanocrystals were structurally characterized by X-ray diffraction,energy...Nickel molybdate(NiMoO4)nanoparticles(NPs)were synthesized by sol-gel method.Utilizing water as solvent providescrystalline nanostructures.These nanocrystals were structurally characterized by X-ray diffraction,energy dispersive X-ray analysis(EDX),and Fourier transform infrared spectra.Compositional stoichiometry was confirmed by EDX technique.The size and shapewere observed by scanning electron microscopy(SEM)and transmission electron microscope(TEM).It was found that the obtainedNPs were pure and single phase crystalline with monoclinic structure.The optical properties were studied by ultraviolet-visiblediffuse reflectance spectroscopy(UV-Vis-DRS)and photoluminescence(PL)measurements at room temperature.The magneticproperties were studied by vibrating sample magnetometer(VSM)and results showed superparamagnetic behavior of the obtainednanoparticles.Photocatalytic activity of NiMoO4was studied.The photocatalytic activity of NiMoO4was enhanced with the additionof TiO2.The catalysts NiMoO4,TiO2and NiMoO4-TiO2nanocomposites(NC)were tested for photocatalytic degradation(PCD)of4-chlorophenol(4-CP).It was found that PCD efficiency of NiMoO4-TiO2NC was higher than that of pure NiMoO4and TiO2.展开更多
Orthorhombic LiMnO2 cathode materials were synthesized successfully at lower temperature by sol-gel method. When LiMnO2 precursor prepared by sol-gel method was fired in air, the product was a mixture of spinel struct...Orthorhombic LiMnO2 cathode materials were synthesized successfully at lower temperature by sol-gel method. When LiMnO2 precursor prepared by sol-gel method was fired in air, the product was a mixture of spinel structure LiMn2O4 and rock-salt structure Li2MnO3, whereas in argon single-phase orthorhombic LiMnO2 could obtain at the range of 750℃ to 920℃. The substitution of Mn by Zn2+ or Co3+ in LiMnO2 led to the structure of LiMnO2 transiting to Qα-LiFeO2. The results of electrochemical cycles indicated that the discharged capacity of orthorhombic-LiMnO2 was smaller at the initial stages, then gradually increased with the increasing of cycle number, finally the capacity stabilized to certain value after about 10th cycles. This phenomenon reveals that there is an activation process for orthorhombic LiMnO2 cathode materials during electrochemical cycles, which is a phase transition process from orthorhombic LiMnO2 to tetragonal spinel Li2Mn2O4. The capacity of orthorhombic LiMnO2 synthesized at lower temperature is larger than that synthesized at high temperature.展开更多
Green synthesis is an alternative method for obtaining nanoparticles for environmentally friendly purposes. The present work describes the synthesis and characterization of titanium oxide nanoparticles, starting from ...Green synthesis is an alternative method for obtaining nanoparticles for environmentally friendly purposes. The present work describes the synthesis and characterization of titanium oxide nanoparticles, starting from three natural sources: orange peel, hibiscus rosa sinensis and Aloe vera. Titanium (IV) tetrabutoxide in ethanol solution was used as precursor. The methodology used was based on the sol-gel technique, through which TiO<sub>2</sub> nanoparticles were obtained in the anatase phase. The characterization of the nanoparticles was carried out by means of x-ray diffraction (XRD), scanning electron microscopy (SEM) and infrared spectrophotometry (FTIR), which allowed the identification of a good degree of purity and crystallinity of the samples obtained.展开更多
A process for in situ synthesis of terbium complex with salicylic acid by a two-step solgel method in silica matrix has been proposed. The luminescence properties of the silica gelscodoped with terbium and salicylic a...A process for in situ synthesis of terbium complex with salicylic acid by a two-step solgel method in silica matrix has been proposed. The luminescence properties of the silica gelscodoped with terbium and salicylic acid have also been discussed with respect to that of the geldoped with terbium and that of pure terbium complex with salicylic acid.展开更多
In-situ synthesis of ternary europium complex with thenoyltrifluoacetone (TTA) and 1,10-phenanthroline (phen) in titania matrix in the presence of dimethylformamide (DMF) by a sol-gel process was described, which was ...In-situ synthesis of ternary europium complex with thenoyltrifluoacetone (TTA) and 1,10-phenanthroline (phen) in titania matrix in the presence of dimethylformamide (DMF) by a sol-gel process was described, which was confirmed by the luminescence excitation spectra and infrared spectra. The titania gel that contains europium complex exhibits Eu3+ characteristic emission bands and presents a longer fluorescence lifetime than the pure complexes dissolved in ethanol solution. The concentration effect on the luminescence intensity was also investigated.展开更多
In nearly all chemical and petrochemical systems, separation of products generally accounts for more than 50% of the capital cost and the greatest part of the energy consumption. It is generally believed that membrane...In nearly all chemical and petrochemical systems, separation of products generally accounts for more than 50% of the capital cost and the greatest part of the energy consumption. It is generally believed that membrane systems can offer benefits in both reducing the energy consumption of the separation stages and lowering the capital expenditure （CAPEX）. Microporous ceramic membranes have the potential to overcome the limitation in polymer membranes operation, which has been the subject of a large amount of research worldwide in the last two decades. And most of the research has aimed at the production of the asymmetric multilayered membrane based on amorphous oxides by sol-gel techniques. The paper is to give an overview of publications on ceramic membranes, including less common materials of titania, zirconia, which can be used for pervaporation in corrosive media. Commercially available microporous membranes based on these membrane materials and the membrane economics are also summarized.展开更多
An effective and reproducible preparation of silica sol nanospheres via a modified sol-gel process has been described. Monodisperse and stable silica sol nanospheres with uniformsize were successfully obtained through...An effective and reproducible preparation of silica sol nanospheres via a modified sol-gel process has been described. Monodisperse and stable silica sol nanospheres with uniformsize were successfully obtained through the optimized synthesis in which the mixture of tetraethyl orthosilicate （TEOS） and ethanol was followed by the addition of water and ammonium hydroxide （NH3） separately, and the size of silica sol spheres was strictly controlled in the range of 25-119 nm with a narrow size distribution by fine adjustment of several reaction parameters. Results showed that in the presence of low concentration of TEOS, spheres size rose first and reached maximum when H2O concentration was up to 66 g/L. However, the diameter of silica sol spheres decreased above 66 g/L of H2O concentration. Furthermore, it was also found that the size and size distribution of silica sol nanospheres were affected by NH3 concentration. As NH3 concentration increased from 15 to 35 g/L, the diameter declined from 83 to 64 nm. Nevertheless, higher NH3 concentration would result in relatively broad size distribution, and gelation occurred when NH3 concentration reached 44 g/L. In addition, the effect of the different feed rates ofNH3 on the size growth of silica sol nanospheres was also discussed.展开更多
Autoigniting synthesis of gel from Ba(NO_3)_2, TiO(NO_3)_2 and C_6H_8O_7centre dot H_2O aqueous solution was investigated at an initial temperature of 600 deg C andtetragonal BaTiO_3 nanopowder with particle size of 8...Autoigniting synthesis of gel from Ba(NO_3)_2, TiO(NO_3)_2 and C_6H_8O_7centre dot H_2O aqueous solution was investigated at an initial temperature of 600 deg C andtetragonal BaTiO_3 nanopowder with particle size of 80nm was prepared. It is indicated that thespecific surface area of the combustion product before and after calcinations is 14.74 m^2/g and12.49 m^2/g, respectively. The combustion wave is composed of solid phase reaction zone and gaseousphase flame reaction zone. The combustion flame temperature is 1 123 K derived from thermocouplemeasurement. The characteristics and densification behavior of the sol-gel autoigniting synthesizedBaTiO_3 nanopowder were investigated.展开更多
The luminophors MeO-SiO_2:Eu^(3+),Bi^(3+)and MeO-SiO_2Bi^(3+)(Me=Mg.Sr)were synthesized at relatively lower temperature by the sol-gel method using the silica sol as a source of silica.The optimum composition and synt...The luminophors MeO-SiO_2:Eu^(3+),Bi^(3+)and MeO-SiO_2Bi^(3+)(Me=Mg.Sr)were synthesized at relatively lower temperature by the sol-gel method using the silica sol as a source of silica.The optimum composition and synthesis conditions were obtained by studying the excitation and emission spectra and the effects of energy transfer from the Bi^(3+)ions to the Eu^(3+)ions.展开更多
An aqueous sol-gel method for the synthesis of γ-Al2O3 supports has been developed for the use in tar reforming applications. It was determined the influences of two different aluminum precursors (aluminum sec-butoxi...An aqueous sol-gel method for the synthesis of γ-Al2O3 supports has been developed for the use in tar reforming applications. It was determined the influences of two different aluminum precursors (aluminum sec-butoxide (Al[OCH(CH3)CH2CH3]3) and aluminum nitrate (Al(NO3)3)) on the textural and crystallographic properties of Al2O3 supports. Only the formation of γ-Al2O3 is aimed in order to use these alumina materials as catalytic supports, because it presents high specific surface area and pore volume values. Additionally, the synthesis of γ-Al2O3 was realized with the use of a functionalized silicon precursor, [3-(2-aminoethylamino)propyl]trimethoxysilane, called EDAS. By the presence of an ethylenediamine group in this molecule, it is possible to chelate metallic ions and to highly increase their dispersion at a molecular level during the synthesis of metallic catalysts supported on alumina, which is an asset for catalytic applications. So it was developed a synthesis sol-gel procedure for the cogelation between the functionalized silicon alkoxide EDAS and alumina precursor. The alumina supports synthesized with Al(NO3)3 as precursor presented higher porous values than the ones obtained with aluminium sec-butoxide precursor. Since nitrate salts are much easier to handle than alkoxides, these observations allowed validating Al(NO3)3 as aluminum source for the future synthesis procedures for metallic catalysts supported on alumina.展开更多
Bismuth molybdate （Bi2MoO6） nano-particles （NPs） were synthesized using bismuth nitrate, ammonium molybdate, citric acid and ethyl cellulose by a simple sol-gel method. The structure, morphology, opto-magnetic and...Bismuth molybdate （Bi2MoO6） nano-particles （NPs） were synthesized using bismuth nitrate, ammonium molybdate, citric acid and ethyl cellulose by a simple sol-gel method. The structure, morphology, opto-magnetic and photocatalytic properties of the obtained powder were characterized by X-ray diffraction （XRD）, Fourier transform infrared （FT-IR） spectra, high resolution scanning electron microscopy （HRSEM）, energy dispersive X-ray （EDX）, ultraviolet-visible diffuse reflectance spectra （DRS）, photoluminescence （PL） spectra and vibrating sample magnetometer （VSM） techniques. The XRD, FT-IR and EDX results indicate that the resultant powder is pure and single phase crystalline Bi2MoO6 with orthorhombic structure. The HRSEM image shows that the morphology of obtained powder consists with well defined nano-particles structure. The VSM results show superparamagnetic behavior of the obtained nano-particles. The photocatalytic activity of Bi2MoO6 nano-particles was performed. The addition of TiO2 catalyst enhances the photocatalytic activity of Bi2MoO6 nano-particles. The catalysts Bi2MoO6, TiO2 and mixed oxide catalyst Bi2MoO6-TiO2 nano-composites （NCs） were tested for the photocatalytic degradation （PCD） of 4-chlorophenol （4-CP）. It is found that the PCD efficiency of Bi2MoO6-TiO2 NCs is higher than that of pure Bi2MoO6 and TiO2 catalysts.展开更多
Multiwall carbon nanotubes （MWNTs） and alumina are combined to give a new type of nanohybrid for Fisher-Tropsch synthesis （FTS） catalyst support. Alumina nano-particles （10 wt%） were introduced directly on funct...Multiwall carbon nanotubes （MWNTs） and alumina are combined to give a new type of nanohybrid for Fisher-Tropsch synthesis （FTS） catalyst support. Alumina nano-particles （10 wt%） were introduced directly on functionalized MWNTs by a modified sol-gel method. Microstructure observations show that alumina particles were homogeneously dispersed on the inside and outside of modified MWNTs surfaces. 15 wt% cobalt loading catalysts were prepared with this nanohybrid and γ-alumina as a reference, using a sol-gel technique and wet impregnation method respectively. These catalysts were characterized by TEM, XRD, N2-adsorption, H2 chemisorption and TPR. The deposition of cobalt nanoparticles synthesized by sol-gel technique on the MWNTs nanohybrid shift the reduction peaks to a low temperature, indicating higher reducibility for uniform cobalt particles. Nanohybrid also aided in high dispersion of metal clusters and high stability and performance of catalyst. The proposed MWNTs nanohybrid-supported cobalt catalysts showed the improved FTS rate （gHc/（gcat.min））, CO conversion （%）, and water gas shift rate （WGS）（gcoz/（gcat.h）） of 0.012, 52, and 30E-3, respectively, as compared to those of 0.007, 25, and 18E-3, respectively, on the γ-alumina-supported cobalt catalysts with the same Co loading.展开更多
Evolutionary algorithm is applied for distillation separation sequence optimization synthesis problems with combination explosion. The binary tree data structure is used to describe the distillation separation sequenc...Evolutionary algorithm is applied for distillation separation sequence optimization synthesis problems with combination explosion. The binary tree data structure is used to describe the distillation separation sequence, and it is directly applied as the coding method. Genetic operators, which ensure to prohibit illegal filial generations completely, are designed by using the method of graph theory. The crossover operator based on a single parent or two parents is designed successfully. The example shows that the average ratio of search space from evolutionary algorithm with two-parent genetic operation is lower, whereas the rate of successful minimizations from evolutionary algorithm with single parent genetic operation is higher.展开更多
文摘The ZnO molecule plays an important role in the industry due to it special features, anti-corrosion anti-bacterial properties, as well as due to its low electrical conductivity and heat resistance. In these experimental researches, the sol-gel method was chosen, which enables control of nucleation, aging and growth of particles in the solution. ZnO synthesis was prepared utilizing chemical method with Zinc acetate dyhidrate and NaOH with the appropriate methanol solvent and heating (60˚C). The methods used in identification and characterization are FTIR, UV/VIS, OPTICAL MICROSCOPY, SEM and XRD. The FTIR spectra of synthesized ZnO with corresponding ones show characteristic bands at the corresponding wavelengths, which confirm the presence of ZnO nanoparticles. SEM characterization of ZnO shows the morphology of needle-shaped nanoparticles. XRD spectar in this research by chemical method indicates the particle size of 17.76 nm.
文摘The vapor recompression heat pump(VRHP) distillation technology offers significant improvements in energy efficiency for distillation systems with small temperature differences between the top and bottom of the column. However, the separation of wide-boiling binary mixtures leads to substantial temperature differences between the top and bottom of the column. This limits the applicability of conventional VRHP due to high capital costs and strict performance requirements of the compressor. To overcome these challenges and to accommodate compressor operating conditions, a novel synthesis and design method is introduced to integrate VRHPs with wide-boiling binary mixture distillation columns(WBMDCs). This method enables quick determination of an initial configuration for the integrated WBMDC-VRHP system and helps identify the optimum configuration with the minimum total annual cost. Two examples, namely the separation of benzene/toluene and isopropanol/chlorobenzene, are employed to derive optimum configurations of the WBMDC-VRHP and compare them with the WBMDC. A systematic comparison between the WBMDC-VRHP and WBMDC demonstrates the superior steady-state performance and economic efficiency of the WBMDC-VRHP.
基金the National Natural Science Foundation of China(Nos.52072151,52171211,52102253,52271218,U22A20145)the Jinan Independent Innovative Team(2020GXRC015)+1 种基金the Major Program of Shandong Province Natural Science Foundation(ZR2021ZD05)the Science and Technology Program of University of Jinan(XKY2119).
文摘Focused exploration of earth-abundant and cost-efficient non-noble metal electrocatalysts with superior hydrogen evolution reaction(HER)performance is very important for large-scale and efficient electrolysis of water.Herein,a sandwich composite structure(designed as MS-Mo2C@NCNS)ofβ-Mo2C hollow nanotubes(HNT)and N-doped carbon nanosheets(NCNS)is designed and prepared using a binary NaCl–KCl molten salt(MS)strategy for HER.The temperature-dominant Kirkendall formation mechanism is tentatively proposed for such a three-dimensional hierarchical framework.Due to its attractive structure and componential synergism,MS-Mo2C@NCNS exposes more effective active sites,confers robust structural stability,and shows significant electrocatalytic activity/stability in HER,with a current density of 10 mA cm-2 and an overpotential of only 98 mV in 1 M KOH.Density functional theory calculations point to the synergistic effect of Mo2C HNT and NCNS,leading to enhanced electronic transport and suitable adsorption free energies of H*(ΔGH*)on the surface of electroactive Mo2C.More significantly,the MS-assisted synthetic methodology here provides an enormous perspective for the commercial development of highly active non-noble metal electrocatalysts toward efficient hydrogen evolution.
文摘The nitrogen-doped and （metal, nitrogen）-codoped TiO2 photocatalysts （metal = Ag, Ce, Fe, La） were synthesized by sol-gel auto-igniting synthesis （SAS） with the complex compound sol of TiCl4-NH4NO3-citri acid-metal nitrate- NH3.H20 as a precursor. The products were characterized by means of XRD, XPS, and UV-Vis diffuse reflectance spectra, and their photocatalytic activity was investigated under visible light. It was found that all the synthesized powders showed good absorption for visible light, and that the radius and alterable valence states of doping metallic cations played important roles on their photocatalytic activity. These results were discussed in detail.
文摘（La, N） co-doped TiO2 photocatalysts were synthesized using TiC14 sol-gel autoignidng synthesis （SAS） starting from a complex compound system of TiCl4-La（NO3）3-citric acid-NH4NO3-NHyH2O, in which the （La, N） co-doped process was accompushed in the formation of TiO2 nanocrystals. The prepared samples were characterized by using X-ray diffraction （XRD）, X-ray photoemission spectroscopy （XPS） and UV-vis diffuse reflectance spectra. The results indicated that nitrogen and lanthanum were incorporated into the lattice and interstices of titania nanocrystals, which resulted in narrowing the band gap and promoting the separation of photoexcited hole-electron pairs, respectively, and showing expected red-shifts and enhanced photocatalytic activity under visible light. The mechanism on nitrogen doping and enhancement in photocatalyfic activity of （La, N） co-doped titania by SAS was discussed in detail.
基金supported by the National Natural Science Foundation of China(51602313 and 51764008)Science and Technology Project of Guizhou Province(Qiankehe No.2016,7439).
文摘Micro/nanostructured SiOx/C composite was firstly synthesized by carbothermal reduction of silica-carbon binary xerogel.The homogeneous dispersion feature of the two components in binary xerogel contributes to effectively carbothermally reduce the O/Si atomic ratio,enhancing the electrochemical activity of the SiOx component.The micron-sized SiOx/C spheres are composed of many near-spherical nanoparticles.The synthesized SiOx/C exhibits a stable and high reversible capacity of 830 m A·h·g^-1 for 100 cycles,and excellent rate-capability.The homogeneous dispersion structure of phases,the micro/nanostructure and the high electrochemical activity of SiOx component combinedly contribute the excellent electrochemical performance.
基金National High Technology Research and Development Program of China (2004AA332060)
文摘Using hydrous aluminum chloride （AlCl3·6H2O） and silicon ethoxide （Si （OC2H5）4） as raw materials, a kind of nano-sized mullite powder was synthesized with the sol-gel process at the medium calcination temperature. The microstructures of the alumina-silica binary aerogel and calcined nano-sized materials were investigated by means of thermogravimetry-differential thermal analysis （TG-DTA）, scanning electron microscopy （SEM） and X-ray diffractometer （XRD）. The results show that the mullitization of Al2O3-SiO2 in gel starts from about 1 000℃ and its formation ofmullite takes place in the range of 1 100℃-1 250 ℃. The size of the nano-sized mullite powder calcined at 1 250 ℃ is measured to be about 30 nm.
基金support from the Caplin Point Laboratories Limited,Chennai,India
文摘Nickel molybdate(NiMoO4)nanoparticles(NPs)were synthesized by sol-gel method.Utilizing water as solvent providescrystalline nanostructures.These nanocrystals were structurally characterized by X-ray diffraction,energy dispersive X-ray analysis(EDX),and Fourier transform infrared spectra.Compositional stoichiometry was confirmed by EDX technique.The size and shapewere observed by scanning electron microscopy(SEM)and transmission electron microscope(TEM).It was found that the obtainedNPs were pure and single phase crystalline with monoclinic structure.The optical properties were studied by ultraviolet-visiblediffuse reflectance spectroscopy(UV-Vis-DRS)and photoluminescence(PL)measurements at room temperature.The magneticproperties were studied by vibrating sample magnetometer(VSM)and results showed superparamagnetic behavior of the obtainednanoparticles.Photocatalytic activity of NiMoO4was studied.The photocatalytic activity of NiMoO4was enhanced with the additionof TiO2.The catalysts NiMoO4,TiO2and NiMoO4-TiO2nanocomposites(NC)were tested for photocatalytic degradation(PCD)of4-chlorophenol(4-CP).It was found that PCD efficiency of NiMoO4-TiO2NC was higher than that of pure NiMoO4and TiO2.
基金supported by the National Natural Science Foundation of China under grant No.59972026.
文摘Orthorhombic LiMnO2 cathode materials were synthesized successfully at lower temperature by sol-gel method. When LiMnO2 precursor prepared by sol-gel method was fired in air, the product was a mixture of spinel structure LiMn2O4 and rock-salt structure Li2MnO3, whereas in argon single-phase orthorhombic LiMnO2 could obtain at the range of 750℃ to 920℃. The substitution of Mn by Zn2+ or Co3+ in LiMnO2 led to the structure of LiMnO2 transiting to Qα-LiFeO2. The results of electrochemical cycles indicated that the discharged capacity of orthorhombic-LiMnO2 was smaller at the initial stages, then gradually increased with the increasing of cycle number, finally the capacity stabilized to certain value after about 10th cycles. This phenomenon reveals that there is an activation process for orthorhombic LiMnO2 cathode materials during electrochemical cycles, which is a phase transition process from orthorhombic LiMnO2 to tetragonal spinel Li2Mn2O4. The capacity of orthorhombic LiMnO2 synthesized at lower temperature is larger than that synthesized at high temperature.
文摘Green synthesis is an alternative method for obtaining nanoparticles for environmentally friendly purposes. The present work describes the synthesis and characterization of titanium oxide nanoparticles, starting from three natural sources: orange peel, hibiscus rosa sinensis and Aloe vera. Titanium (IV) tetrabutoxide in ethanol solution was used as precursor. The methodology used was based on the sol-gel technique, through which TiO<sub>2</sub> nanoparticles were obtained in the anatase phase. The characterization of the nanoparticles was carried out by means of x-ray diffraction (XRD), scanning electron microscopy (SEM) and infrared spectrophotometry (FTIR), which allowed the identification of a good degree of purity and crystallinity of the samples obtained.
文摘A process for in situ synthesis of terbium complex with salicylic acid by a two-step solgel method in silica matrix has been proposed. The luminescence properties of the silica gelscodoped with terbium and salicylic acid have also been discussed with respect to that of the geldoped with terbium and that of pure terbium complex with salicylic acid.
文摘In-situ synthesis of ternary europium complex with thenoyltrifluoacetone (TTA) and 1,10-phenanthroline (phen) in titania matrix in the presence of dimethylformamide (DMF) by a sol-gel process was described, which was confirmed by the luminescence excitation spectra and infrared spectra. The titania gel that contains europium complex exhibits Eu3+ characteristic emission bands and presents a longer fluorescence lifetime than the pure complexes dissolved in ethanol solution. The concentration effect on the luminescence intensity was also investigated.
基金The authors would like to thank the National Natural Science Foundation of China(No.20676149)the Scientific Research Foundation for the Returned 0verseas Chinese Scholars,State Education Ministrythe research foundation of the State Key Laboratory of Heavy 0il Processing,China University of Petroleum(Beijing),for financial support.
文摘In nearly all chemical and petrochemical systems, separation of products generally accounts for more than 50% of the capital cost and the greatest part of the energy consumption. It is generally believed that membrane systems can offer benefits in both reducing the energy consumption of the separation stages and lowering the capital expenditure （CAPEX）. Microporous ceramic membranes have the potential to overcome the limitation in polymer membranes operation, which has been the subject of a large amount of research worldwide in the last two decades. And most of the research has aimed at the production of the asymmetric multilayered membrane based on amorphous oxides by sol-gel techniques. The paper is to give an overview of publications on ceramic membranes, including less common materials of titania, zirconia, which can be used for pervaporation in corrosive media. Commercially available microporous membranes based on these membrane materials and the membrane economics are also summarized.
基金Funded by the Guangdong Well-Silicasol Company Limited,China
文摘An effective and reproducible preparation of silica sol nanospheres via a modified sol-gel process has been described. Monodisperse and stable silica sol nanospheres with uniformsize were successfully obtained through the optimized synthesis in which the mixture of tetraethyl orthosilicate （TEOS） and ethanol was followed by the addition of water and ammonium hydroxide （NH3） separately, and the size of silica sol spheres was strictly controlled in the range of 25-119 nm with a narrow size distribution by fine adjustment of several reaction parameters. Results showed that in the presence of low concentration of TEOS, spheres size rose first and reached maximum when H2O concentration was up to 66 g/L. However, the diameter of silica sol spheres decreased above 66 g/L of H2O concentration. Furthermore, it was also found that the size and size distribution of silica sol nanospheres were affected by NH3 concentration. As NH3 concentration increased from 15 to 35 g/L, the diameter declined from 83 to 64 nm. Nevertheless, higher NH3 concentration would result in relatively broad size distribution, and gelation occurred when NH3 concentration reached 44 g/L. In addition, the effect of the different feed rates ofNH3 on the size growth of silica sol nanospheres was also discussed.
文摘Autoigniting synthesis of gel from Ba(NO_3)_2, TiO(NO_3)_2 and C_6H_8O_7centre dot H_2O aqueous solution was investigated at an initial temperature of 600 deg C andtetragonal BaTiO_3 nanopowder with particle size of 80nm was prepared. It is indicated that thespecific surface area of the combustion product before and after calcinations is 14.74 m^2/g and12.49 m^2/g, respectively. The combustion wave is composed of solid phase reaction zone and gaseousphase flame reaction zone. The combustion flame temperature is 1 123 K derived from thermocouplemeasurement. The characteristics and densification behavior of the sol-gel autoigniting synthesizedBaTiO_3 nanopowder were investigated.
文摘The luminophors MeO-SiO_2:Eu^(3+),Bi^(3+)and MeO-SiO_2Bi^(3+)(Me=Mg.Sr)were synthesized at relatively lower temperature by the sol-gel method using the silica sol as a source of silica.The optimum composition and synthesis conditions were obtained by studying the excitation and emission spectra and the effects of energy transfer from the Bi^(3+)ions to the Eu^(3+)ions.
文摘An aqueous sol-gel method for the synthesis of γ-Al2O3 supports has been developed for the use in tar reforming applications. It was determined the influences of two different aluminum precursors (aluminum sec-butoxide (Al[OCH(CH3)CH2CH3]3) and aluminum nitrate (Al(NO3)3)) on the textural and crystallographic properties of Al2O3 supports. Only the formation of γ-Al2O3 is aimed in order to use these alumina materials as catalytic supports, because it presents high specific surface area and pore volume values. Additionally, the synthesis of γ-Al2O3 was realized with the use of a functionalized silicon precursor, [3-(2-aminoethylamino)propyl]trimethoxysilane, called EDAS. By the presence of an ethylenediamine group in this molecule, it is possible to chelate metallic ions and to highly increase their dispersion at a molecular level during the synthesis of metallic catalysts supported on alumina, which is an asset for catalytic applications. So it was developed a synthesis sol-gel procedure for the cogelation between the functionalized silicon alkoxide EDAS and alumina precursor. The alumina supports synthesized with Al(NO3)3 as precursor presented higher porous values than the ones obtained with aluminium sec-butoxide precursor. Since nitrate salts are much easier to handle than alkoxides, these observations allowed validating Al(NO3)3 as aluminum source for the future synthesis procedures for metallic catalysts supported on alumina.
文摘Bismuth molybdate （Bi2MoO6） nano-particles （NPs） were synthesized using bismuth nitrate, ammonium molybdate, citric acid and ethyl cellulose by a simple sol-gel method. The structure, morphology, opto-magnetic and photocatalytic properties of the obtained powder were characterized by X-ray diffraction （XRD）, Fourier transform infrared （FT-IR） spectra, high resolution scanning electron microscopy （HRSEM）, energy dispersive X-ray （EDX）, ultraviolet-visible diffuse reflectance spectra （DRS）, photoluminescence （PL） spectra and vibrating sample magnetometer （VSM） techniques. The XRD, FT-IR and EDX results indicate that the resultant powder is pure and single phase crystalline Bi2MoO6 with orthorhombic structure. The HRSEM image shows that the morphology of obtained powder consists with well defined nano-particles structure. The VSM results show superparamagnetic behavior of the obtained nano-particles. The photocatalytic activity of Bi2MoO6 nano-particles was performed. The addition of TiO2 catalyst enhances the photocatalytic activity of Bi2MoO6 nano-particles. The catalysts Bi2MoO6, TiO2 and mixed oxide catalyst Bi2MoO6-TiO2 nano-composites （NCs） were tested for the photocatalytic degradation （PCD） of 4-chlorophenol （4-CP）. It is found that the PCD efficiency of Bi2MoO6-TiO2 NCs is higher than that of pure Bi2MoO6 and TiO2 catalysts.
基金supported by the Research Council of the Research Institute of Petroleum Industrythe Research and Development of the National Iranian Oil Company
文摘Multiwall carbon nanotubes （MWNTs） and alumina are combined to give a new type of nanohybrid for Fisher-Tropsch synthesis （FTS） catalyst support. Alumina nano-particles （10 wt%） were introduced directly on functionalized MWNTs by a modified sol-gel method. Microstructure observations show that alumina particles were homogeneously dispersed on the inside and outside of modified MWNTs surfaces. 15 wt% cobalt loading catalysts were prepared with this nanohybrid and γ-alumina as a reference, using a sol-gel technique and wet impregnation method respectively. These catalysts were characterized by TEM, XRD, N2-adsorption, H2 chemisorption and TPR. The deposition of cobalt nanoparticles synthesized by sol-gel technique on the MWNTs nanohybrid shift the reduction peaks to a low temperature, indicating higher reducibility for uniform cobalt particles. Nanohybrid also aided in high dispersion of metal clusters and high stability and performance of catalyst. The proposed MWNTs nanohybrid-supported cobalt catalysts showed the improved FTS rate （gHc/（gcat.min））, CO conversion （%）, and water gas shift rate （WGS）（gcoz/（gcat.h）） of 0.012, 52, and 30E-3, respectively, as compared to those of 0.007, 25, and 18E-3, respectively, on the γ-alumina-supported cobalt catalysts with the same Co loading.
文摘Evolutionary algorithm is applied for distillation separation sequence optimization synthesis problems with combination explosion. The binary tree data structure is used to describe the distillation separation sequence, and it is directly applied as the coding method. Genetic operators, which ensure to prohibit illegal filial generations completely, are designed by using the method of graph theory. The crossover operator based on a single parent or two parents is designed successfully. The example shows that the average ratio of search space from evolutionary algorithm with two-parent genetic operation is lower, whereas the rate of successful minimizations from evolutionary algorithm with single parent genetic operation is higher.
