Degradation of n-butyl xanthate using fly ash as heterogeneous Fenton-like catalyst

Heterogeneous Fenton-like process using fly ash as a catalyst was studied to degrade n-butyl xanthate form aqueous solution. The different reaction parameters on the degradation efficiency of the process were investigated. The fly ash/H2O2 catalyst possesses a high oxidation activity for n-butyl xanthate degradation in aqueous solution. It is found that both the dosage of catalyst and initial solution pH significantly affect the n-butyl xanthate conversion efficient. The results indicate that by using 1.176 mmol/L H2O2 and 1.0 g/L fly ash catalyst with mass fraction of 4.14% Fe（III） oxide at pH 3.0, almost 96.90% n-butyl xanthate conversion and over 96.66% COD removal can be achieved within 120 min with heterogeneous catalysis by fly ash. CS2 as an intermediate of n-butyl xanthate oxidation. Finally, it is demonstrated that the fly ash/H2O2 catalytic oxidation process can be an efficient method for the treatment of n-butyl xanthate containing wastewater.     

Preparation and characterization of Cu-doped mesoporous CeO2for CO oxidation简

Mesoporous CeO2 was first synthesized by hydrothermal method,and then used to synthesize different contents of CuO）x/CeO2（x：molar ratio of Cu to Ce） by deposition-precipitation method.These materials were characterized by X-ray diffraction（XRD）,N2 adsorption and desorption,H2 temperature programmed reduction（H2-TPR） and O2 temperature programmed desorption（O2-TPD） to study the crystal structure,surface area,and the mechanism of CO oxidation.The results show that,on XRD patterns,no evidence of CuO diffraction peaks is present until Cu loading is increased to 20%.The BET surface area decreases noticeably with the increase of Cu content.Compared with other samples,the better reducibility and activity oxygen species of（CuO）10%/CeO2coincide with its better catalytic activity.     

Preparation of Cerium Doped Cu/MIL-53(A1) Catalyst and Its Catalytic Activity in CO Oxidation Reaction

Metal-organic framework(MOF) material MIL-53(A1) with high thermal stability was prepared by a solvothermal method,serving as a support material of cerium doped copper catalyst(Ce-Cu)/MIL-53(A1) material for CO oxidation with high catalytic activity.The catalytic performance between the(CuCe)/MIL-53(A1) and the Cu/MIL-53(A1) catalytic material was compared to understand the catalytic behavior of the catalysts.The catalysts were characterized by thermogravimetric-differential scanning calorimetry(TGDSC),N_2 adsorption- desorption,X-ray diffraction(XRD),and transmission electron microscopy(TEM).The characterization results showed that MIL-53(A1) had good stability and high surface areas,the(Ce-Cu)nanoparticles on the MIL-53(A1) support was uniform.Therefore,the heterogeneous catalytic composite materials(Ce-Cu)/MIL-53(A1) catalyst exhibited much higher activity than that of the Cu/MIL- 53(A1) catalyst in CO oxidation test,with 100%conversion at 80 ℃.The results reveal that(Cu-Ce)/MIL-53(A1) is the suitable candidate for achieving low temperature and higher activity CO oxidation catalyst of MOFs.     

Catalytic Decomposition of Methylene Chloride by Sulfated Titania Catalysts

Catalytic decomposition of methylene chloride in air below 300℃ was studied. Sulfated tiaznia was very effective in converting 959ppm methylene chloride selectively to CO, CO2 and HCl. Complete decomposi-tion of methylene chloride was achieved at low temperature( 275℃ ). It was found that the acidic property of cata-lyst was a determinaat factor for the catalytic activity. The presence of water vapor in the feed stream remarkably reduced the catalytic activity, which could be due to the blockage of acidic sites on the surface of catalyst by water molecules. A bifunctional catalyst comprising copper oxide was developed to improve the selectivity of catalytic oxi-thrtion , which indicated that copper oxide can promote the deep oxidation of methylene chloride. The crystal form of TiO2 imposes an important influence upon the catalytic oxidation.     

Microstructural characterization of internal oxidation of AgCu alloy

The internal oxidation of AgCu alloys with atomic percentage 0.8,3 3, 6 3 and 9 5 of Cu in air at 750℃ and 850℃ has been studied. It was found that CuO particles precipitated homogeneously on the surface of AgCu alloys except for Ag-9.5% (atomic percentage) Cu. The latter exhibited the agglomerated precipitation of CuO particle cluster on the surface. The experimental results also revealed that the nucleation and growth of CuO oxide evidently varied with the change of Cu contents or oxidation temperature. When both Cu content and exposure temperature were low, the precipitation and the growth of internal CuO oxide were consistent with the prediction by the classical Bohm-Kahlweit mode, but the abnormal phenomenon of nucleation and growth of the CuO oxide was observed when the Cu content or the exposure temperature was increased. As a result of investigation of the atomic structure of different internally oxidized AgCu alloys, it is proposed that the stacking fault tetrahedra(SFT), which were found in     

Synthesis,characterization and catalytic properties of mesoporous HPMo/SiO<Subscript>2</Subscript> composite

A novel mesoporous HPMo/SiO2 composite was synthesized by the sol-gel method with triblock copolymer EO20PO70EO20 as template.The properties of the product were characterized by X-ray diffraction,transmission electron microscopy,N2 adsorption-desorption isotherms,Fourier transform infrared spectrometer and inductively-coupled plasma analysis.The experimental results show that the product has a very ordered hexagonal mesostructure,and the HPMo is immobilized into the framework of silica.The final mesoporous composite shows excellent stability in polar solvents.Results of catalytic tests indicate that the composite is an effective catalyst for oxidation of dibenzothiophen,and there are few activity losses even after the third cycle of uses.The high catalytic activity and good insolubility make it a promising catalyst in oxidative desulfurization process.     

Preparation of uitrafine α-Al2O3 powders by catalytic sintering of ammonium aluminum carbonate hydroxide at low temperature

The precursor of ammonium aluminum carbonate hydroxide was synthesized by using aluminum sulfate （Al2 （SO4）3 ） and ammonium carbonate（（NH4 ）2CO3 ）. The effects of α-Al2 O3 seeds and mixture composed of α- Al2O3 and ammonium nitrate, as well as multiplex catalysts （AT） on phase transformation of alumina in sintering process were investigated respectively. The results show that the α-Al2 O3 seeds and the mixture of α-Al2 O3 and ammonium nitrate can lower the phase transformation temperature of α-Al2O3 to different extents while the particles obtained agglomerate heavily. AT has great potential synergistic effects on the phase transformation of alumina and reduces the phase transformation temperature of α-Al2O3 and the trends of necking-formation between particles. Therefore the dispersion of powder particles is improved significantly.     

Preparation,characterization of superacid SO4 2−/ZrO2-SiO2 and its activity on catalytic synthesis of methyl p-nitrobenzoate

Solid superacid SO42-/Zr O2-SiO2 was prepared by dip-impregnation method, and its catalytic activity was tested with esterification of p-nitrobenzoic acid and methanol. The optimum conditions were also found, that is, the molar ratio between silica and zirconia was 10:1, the calcination temperature was 550 ℃ and the soaked consistency of H2SO4 was 1.0 mol?L-1. Under the conditions that the ratio of methanol to acid(m L/g) was 12:1, the amount of catalyst was 0.5 g, the reaction time was 5 h and the stirring speed was 800 r?min-1, the yield of methyl p-nitrobenzoate could reach up to 90.5%. Then the characterizations of cataslyst, including the acidity and types of acidic centers, specific surface area and surface structure was respectively examined by Hammett indicator, in-situ pyridine IR, BET method, FT-IR(KBr), transmission electron microscope(TEM), and X-ray diffraction(XRD). The results showed that the catalyst SO42-/Zr O2-SiO2 was superacid with high specific surface area due to Ho-12.70. It contained acidic sites of Lewis and BrΦnsted, and its surface structure changed after esterification. The zirconia crystal was mainly tetragonal and silica crystal was not found.     

Self-Propagating High-Temperature Reductive Synthesis of TiB_2-Al_2O_3 Composite Powders

TiB2-Al2O3 composite powders were produced by self-propagating high-temperature synthesis(SHS) method with reductive process from B2O3-TiO2-Al system. X-ray diffraction(XRD) and scanning electron microscopy(SEM) analyses show the presence of TiB2 and Al2O3 only in the composite powders produced by SHS. The powders are uniform and free-agglomerate. Transmission electron microscopy (TEM) and high resolution electron microscopy (HREM) observation of microstructure of the composite powders indicate that the interfaces of the TiB2-Al2O3 bond well, without any interfacial reaction products. It is proposed that the good interfacial bonding of the composite powders can be resulted from the TiB2 particles crystallizing and growing on the Al2O3 particles surface with surface defects acting as nucleation centers.     

UV-Shielding and Catalytic Characteristics of Nanoseale Zinc-Cerium Oxides

Fine particles of zinc-cerium oxides （ZCO） used as an ultraviolet filter were prepared via combustion synthesis route. The catalytic activity, UV-shielding performance, surface modification and application of ZCO in polyester varnish were discussed in detail. The experimental results indicate that the photo-catalytic activity of ZCO is much smaller than these of ZnO and TiO2; the oxidation catalytic activity of ZCO is far lower than that of CeO2; the ZCO has shown excellent ultraviolet absorption in the range of UV; addition modified ZCO （MZCO） into polyester will enhance the UV-shielding capability of polyester.     

Microwave-assisted hydroxylation of benzene to phenol with H_2O_2 over FeSO_4/SiO_2

Hydroxyl radicals HO are generated under Fenton-like (Fe2++H2O2→HO?+OH?+Fe3+) catalytic conditions upon microwave irradiation. Liquid-phase direct catalytic oxidation of benzene to phenol was obtained using FeSO4 supported on silica gel as a solid catalyst and hydrogen peroxide as the oxidant. The effects of various parameters, such as the different solvents, the amount of solvent used, the amount of catalyst used, the reaction time, the reaction temperature and the amount of hydrogen peroxide used on the yield of phenol were studied to identify optimum reaction conditions. Conventionally heated reaction gives a phenol yield of 0.6%. A higher phenol yield of 13.9% with a selectivity of 100% is obtained when the reaction mixture was irradiated with micro-wave energy. It is concluded that microwave irradiation offers more effective control of energy input for hydroxyl radical generation that is appropriate for various synthetic reactions.     

Synthesis and performance of mesoporous phosphotungstic acid/alumina composite as a novel oxidative desulfurization catalyst

A series of mesoporous phosphotungstic acid/alumina composites （HPW/Al_2O_3） with various HPW contents were synthesized by evaporation-induced self-assembly method. These composites were characterized by nitrogen adsorption-desorption, TEM, FTIR, and UV-vis, and were tested as catalysts in oxidation desulfurization of model fuel composed of dibenzothiophene （DBT） and hydrocarbon, using H202 as the oxidant. These composites exhibited high activity in catalytic oxidation of DBT in model fuel and good reusing ability. The best performance was achieved by using the mesoporous HPW/Al_2O_3 with 15wt% HPW content, which resulted in a DBT conversion of 98% after 2 h reaction at 343 K, and it did not show significant activity degradation after 3 recycles. Characterization results showed that the mesoporous structure of alumina and the Keggin structure of HPW were preserved in the formed composite. These results suggested that HPW/ Al_2O_3 could be a promising catalyst in oxidative desulfurization process.     

Self-Propagating High-Temperature Reduetive Synthesis of TiB2-Al2O3 Composite Powders

TiB2-Al2O3 composite powders were produced by self-propagating high-temperature synthesis（SHS） method with reductive process from B2O3-TiO2-AI system. X-ray diffraction（XRD） and scanning electron microscopy（SEM） analyses show the presence of TiB2 and Al2O3 only in the composite powders produced by SHS. The powders are uniform and free-agglomerate. Transmission electron microscopy （TEM） and high resolution electron microscopy （HREM） observation of microstructure of the composite powders indicate that the interfaces of the TiB2-Al2O3 bond well, without any interfacial reaction products. It is proposed that the good interfacial bonding of the composite powders can be resulted from the TiB2 particles crystallizing and growing on the Al2O3 particles surface with surface defects acting as nucleation centers.     

Direct spray pyrolysis of aluminum chloride solution for alumina preparation

The effects of pyrolysis mode and pyrolysis parameters on Cl content in alumina were investigated, and the alumina products were characterized by XRD, SEM and ASAP. The experimental results indicate that the spray pyrolysis efficiency is higher than that of static pyrolysis process, and the reaction and evaporation process lead to a multi-plot state of the alumina products by spray pyrolysis. Aluminum phase starts to transform into γ-Al2O3 at spray pyrolysis temperature of 600 °C, which is about 200 °C lower than that of static pyrolysis process. The primary particle size of γ-Al2O3 product is 27.62 nm, and Cl content in alumina products is 0.38% at 800 °C for 20 min.     

Investigation of the Thermal Decomposition Properties of Polyoxymethylene

By testing the melt index （MI）, tensile strength and breaking extension ratio, the thermal ageing rate of polyoxymethylene （POM） was analyzed and compared. The surface morphology and type of function group of POM surface were observed and analyzed by SEM and XPS. The results show that the MI value increases gradually with the ageing time at 120℃, indicating that the thermal oxidation decomposition occurrs slowly. The effect of 20-day thermal ageing on the tensile strength and breaking extension ratio of POM is not obvious, showing that the ageing of POM is quite a long process. After 105-day, thermal ageing cracking and powdering occurr on the POM surface. XPS determination shows the Cls spectra of samples before and after ageing include two peaks of C-C and C-O, while after ageing the content of C-C decreases and the content of C-O increases, indicating that the thermal ageing of POM is mainly the breaking and decomposing of C-C bond. The Ols/Cls ratio of original samples is 56.98% and after 105-day thermal ageing the ratio is 72.92%.     

Synthesis and characterization of Cu-Cr-O nanocomposites

Cu-Cr-O nanocomposites that can be used as additives for the catalytic combustion of AP（ammonium perchlorate）-based solid-state propellants were synthesized via a citric acid（CA） complexing approach. Techniques of TG-DTA, XRD as well as TEM were employed to characterize the thermal decomposition procedure, crystal phase, micro-structural morphologies and grain size of the as-synthesized materials respectively. The results show that well-crystallized Cu-Cr-O nanocomposites can be produced after the CA-Cu-Cr precursors are calcined at 500℃ for 3 h. Phase composition of the as-obtained Cu-Cr-O nanocomposites depends on the molar ratio of Cu to Cr in the starting reactants. Addition of the as-synthesized Cu-Cr-O nanocomposites as catalysts enhances the burning rate as well as lowers the pressure exponent of the AP-based solid-state propellants considerably. Noticeably, catalyst with a Cu/Cr molar ratio of 0.7 exhibits promising catalytic activity with high burning rate and low pressure exponent at all pressures, due to the effective phase interaction between the spinel CuCr2O4 and delafossite CuCrO2 contained in the as-synthesized Cu-Cr-O nanocomposites.     

Synthesis of Li-doped Co3O4 truncated octahedra with improved performances in CO oxidation and lithium ion batteries

Single-crystalline Li-doped Co3O4 truncated octahedra with different doping contents were synthesized by a simple combustion method with the fuel of multi-walled carbon nanotubes(MWCNTs).Controlled experiments showed that the pristine well-defined Co3O4 octahedra were obtained with exposed surfaces of {111} planes without lithium doping.In comparison with the octahedra,the truncated Co3O4 octahedra were composed of original {111} planes and extra {100} planes.It could be attributable to the selective adsorption of lithium ions on the {100} planes,making these planes with higher surface energy coexist with the crystal faces of {111}.Furthermore,the Li-doped truncated octahedra and undoped octahedra were used as catalysts in CO oxidation and as anode materials for Li-ion batteries(LIBs).The measurements exhibited that the Li-doped octahedra with added {100} crystal faces showed improved catalytic activity and electrochemical property because of the exposure of the higher energy faces of {100} and enhanced conductivity by Li doping.     

Storage of hydrogen in floating catalytic carbon nanotubes after graphitizing

Hydrogen storage under moderate pressure (~10 MPa) and ambient temperature (~25℃) in multi-walled carbon nanotubes (MWNTs) prepared by the floating catalyst method is investigated. The capacity of hydrogen adsorption is evaluated based on both the nanotubes diameter and morphology. Indirect evidence indicates that hydrogen adsorption not only occurs on tube surface and interiors, but also in tube interlayers. The results show that the floating catalytic carbon nanotubes might be a candidate hydrogen storage material for fuel cell electric vehicles.     

Systematic Studies on the Aromatization of Light Hydrocarbon(

After studying the deactivation type of ZnNi/HZSM-5 catalyst of aromatization of light hydrocarbon, the conclusion was drawn that carbon deposition was the main one of modified ZSM-5 and the catalytic activity could be recovered by charking. The reactivation mode was presumed on the basis of the investigation of the influence of temperature on reactivation process by static charking in muffle furnace and dynamic charking in reactor. Reactivation process simulating industrial charking process at macroscopic calorific effect was studied in 100 mL miniature continuous fixed-bed reactor. The result shows that charking was a diffusion process forming hot spot in catalyst from outer to inner and maximum reactivation temperature was the most important factor among the influential ones including oxygen content, space velocity, time and maximum temperature. Catalytic activity could be recovered only when temperature was higher than 575℃. Meanwhile, reactivation time was determined by space velocity and oxygen content. The best scheme (low initial burning temperature and single charking) was confirmed from the comparison of the three reactivation ones. According to the third scheme, reactivation time was cut down by one half and catalyst stability was maintained after repeated reactivation with the recovery of ZnNi/HZSM-5 catalytic activity.     

Precipitation of antimony from the solution of sodium thioantimonite by air oxidation in the presence of catalytic agents

The behavior of antimony oxidation in the solution of sodium thioantimonite was studied in the presence of catalytic agents. The catalytic effects of the respective addition of cupric sulfate, sodium tartrate, potassium permanganate, phenol, 1,2-dihydroxybenzene and their combination on the oxidation of sodium thioantimonite were investigated. A pilot test was carried out. The results show that the respective use of sodium tartrate, cupric sulfate, potassium permanganate, phenol and 1,2-dihydroxybenzene have little catalytic effect on the oxidation of sodium thioantimonite. However there exists obvious catalytic oxidation by the combination of 0.25 g/L 1,2-dihydroxybenzene, 0.5 g/L potassium permanganate and 1.0 g/L phenol. Moreover, high blast intensity, the increase of temperature and NaOH concentration favor the oxidation of antimony. The oxidation process of antimony has such advantages as quick reaction and low operation costs. The results of the pilot test are consistent with those of laboratory experiments.