Catalytic Oxidation Method Research Articles

ChemInform Abstract: A Mild and Highly Efficient Laccase‐Mediator System for Aerobic Oxidation of Alcohols

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Fabrication of Hierarchically Porous RuO2–CuO/Al–ZrO2 Composite as Highly Efficient Catalyst for Ammonia-Selective Catalytic Oxidation

A hierarchically porous RuO2–CuO/(Al–ZrO2) nanocomposite, with RuO2 and CuO nanocrystals being homogeneously dispersed in the hierarchically porous structure of Al-doped ZrO2 (Al–ZrO2), has been developed by a hydrothermal and wet impregnation method for efficient ammonia-selective catalytic oxidation (SCO) applications. The microstructures of the RuO2–CuO/Al–ZrO2 nanocomposites were characterized by XRD, TEM, FESEM, EDX elemental mapping, and N2 sorption. XPS analysis and H2-TPR results indicate that the hierarchically porous RuO2–CuO/Al–ZrO2 composites possess a large number of oxygen vacancies and surface catalytic active sites, which endows the composite with high catalytic activity and N2 selectivity for NH3 oxidation. NH3 complete oxidization has been achieved at 195 °C with 100% N2 selectivity over an obtained RuO2–CuO/Al–ZrO2 composite at RuO/CuO = 1:1 (weight rate). The high efficiency of hierarchically porous RuO2–CuO/Al–ZrO2 nanocomposites for ammonia SCO reaction has been attributed to the synergetic catalytic effects among the metal oxides, in which the porous Al–ZrO2 support promotes oxygen activation by the generation of oxygen vacancies due to the Al doping, and the ultrahigh catalytic activity of RuO2 is responsible for the active NH3 oxidation. Successively, CuO plays a role of NO intermediate conversion for enhanced N2 selectivity.

Mechanism Research on Electrochemical Catalytic Oxidation Desulfurization of High Sulfur Coal

Electrochemical desulfurization is a mild chemical desulfurization method. This paper introduces the electrochemical catalytic oxidation method which is used to process High Sulfur Coal samples under acidic condition. Study tells that during the processing of electrochemical catalytic oxidation desulfurization ,pyrite and organic sulfur in coal are oxidized and converted into water soluble sulfur compounds by some active oxygen and other oxidizing agent or high valence ions which are produced on the surface of electrolytic anode.After analyzing the experiments ,another conclusion that the desulfurization process is faster for the added catalyst ion also involving in the reaction is reached.

Vanadium-catalyzed green oxidation of benzylic alcohols in water under air atmosphere

The oxidation of alcohols using catalytic amounts of metal complexes is highly attractive from the viewpoint of green chemistry principles. However, examples of metal complex-catalyzed oxidations of alcohols with O2 using water as the solvent are still rare, and precious metals, high-pressure O2 or air, and a stoichiometric amount of base are often required. In this study, it was found that an oxovanadium-4,4′-t-Bubpy (4,4′-di-tert-butyl-2,2′-bipyridyl) complex exhibited high catalytic activity in the oxidation of benzhydrols under an atmosphere of O2 in water as the sole solvent. Interestingly, this catalytic oxidation method could be applied to the gram-scale aerobic oxidation of alcohols in water under the atmosphere.

Preparation of Supported Fe/SiO2 Catalyst and its Catalytic Performance for Wastewater Treatment

The catalyst Fe/SiO2 was prepared by impregnation method and used as catalyst for treating the dye wastewater by catalytic wet peroxide oxidation method. The catalyst preparation process was optimized, and under the conditions of: the particle size of catalyst carrier was 0.125-0.200 mm, concentration of iron nitrate was 1.10mol/L, calcination temperature was 600 °C, and calcination time was 4h, the catalyst has higher activity and better stability in treating the wastewater.

Catalytic Wet Peroxide Oxidation of Dye Wastewater Using Fe<sub>2</sub>O<sub>3</sub>-CeO<sub>2</sub>/γ-Al<sub>2</sub>O<sub>3</sub> as Catalyst

Fe2O3-CeO2/γ-Al2O3 was used as catalyst for treating the dye wastewater by catalytic wet peroxide oxidation method, the effect of reaction temperature, initial pH value of the wastewater, dosage of catalyst and hydrogen peroxide on the COD removal were studied. Results showed that 90.3% of COD removal rate can be obtained under the condition of 90°C, pH=7, 0.8g catalyst/100 mL wasterwater, and 6mL H2O2 /100 mL wasterwater.

Synthesis and catalytic properties of La or Ce doped hydroxy-FeAl intercalated montmorillonite used as heterogeneous photo Fenton catalysts under sunlight irradiation

A series of La and Ce doped hydroxyl FeAl intercalated montmorillonite (FeAl-Mt) were prepared by a co-intercalation method for catalytic oxidation of Reactive Blue 19 (RB19) by a heterogeneous photo Fenton process under natural sunlight irradiation. The physicochemical properties of the obtained catalysts were deciphered by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure (XAFS) and UV-vis diffuse reflectance spectroscopy (DRS). The results showed that Ce or La doped FeAl Keggin polyoxocations were intercalated into the gallery of montmorillonite and the physicochemical properties of intercalated FeAl Keggin polyoxocations were mildly changed after Ce or La doping, resulting in defects and lattice vacancies. The doping of Ce or La could effectively improve the catalytic performance of FeAl-Mt measured by heterogeneous photo Fenton degradation of RB19 catalyzed by the obtained products. The synergistic effect between the doped element and FeAl intercalated montmorillonite played a crucial role in the enhancement of heterogeneous catalytic activity under natural sunlight irradiation.

Influence Factors of Cu-Fe-La/FSC Catalyst Applications in CWAO Technology

Catalytic Wet Air Oxidation (CWAO) is one of advanced oxidation methods about organic wastewater treatment, and the treatment effect of high concentration organic wastewater is remarkable with this method. In this study, the influence factors of the reaction temperature, the reaction pressure and the influent pH were researched on the treatment of the printing and dyeing wastewater with Cu-Fe-La/FSC catalyst, by the single factor experiments and Catalytic Wet Air Oxidation (CWAO) method. Then the catalysts were evaluated by two aspects of the activity and stability. The results show that: with the increase of the reaction temperatures and the reaction pressures, and with the decrease of the influent pH, the CODCrremoval rate improved and the effluent pH reduced. However, the amount of dissolution catalyst components increased with the improvement of treatment effect and the extension of reaction time. By weighing the activity and stability of the catalysts, the optimized reaction temperature, the reaction pressure and the influent pH are 180 °C, 2.5 MPa and 7.25, respectively. Under the optimized operating conditions, the printing and dyeing wastewater with CODCrof 2000 mg/L reaches the CODCrremoval rate of 78.2%, and the dissolvedC[Cu] andC[Fe] of the catalysts are 12.2 and 10.9 mg/L, respectively. Therefore, the catalyst Cu-Fe-La/FSC presents the high activity and stability.

Catalyst Activity on Landfill Leachate Treatment with CWAO Method

The landfill leachate belongs to typical high concentration and organic pollutant wastewater. In this study, Landfill leachate was treated with Catalytic Wet Air Oxidation (CWAO) method. The monitoring indicators consist of CODCr, absorbance, pH and chroma. The results show that the activity of the catalysts arrange from high to low: Co (NO3)2, Cu (NO3)2, Fe (NO3)3, CuSO4, Fe2(SO4)3, Mn (NO3)2, FeSO4, Zn (NO3)2, Bi (NO3)3, Zr (NO3)2, Ni (NO3)2; For the same kind of metal, the catalytic activity of nitrates is higher than that of sulfates; Relative to the distribution of catalyst, the activity of Co (NO3)2 is the strongest. With the optimized catalyst Co (NO3)2 , the landfill leachate has been treated. With the extension of reaction time, the effluent CODCr, absorbance and chroma reduced, but the wastewater biodegradability indicator B/C improved. At the reaction time of 90 min, the CODCr of landfill leachate reduced to 7176 mg/L, and the absorbance and the chroma reduced to 9.1 and 1600 times, respectively. The above results show that the activity of catalyst Co (NO3)2 is high, and the biochemical indicators B/C of wastewater is higher than the critical value of 0.3. Therefore, the treated wastewater shows the good biodegradability, and the chosen catalyst of Co (NO3)2 presents the high activity.

LaMnO3 perovskite oxides prepared by different methods for catalytic oxidation of toluene

Perovskite-type oxides of LaMnO3 (LMO) were synthesized by citrate sol–gel (SG), glycine combustion (GC) and co-precipitation (CP) methods, respectively. The physicochemical properties of these LaMnO3 materials were characterized by XRD, N2 sorption, H2-TPR and O2-TPD. Their catalytic performances were evaluated for the oxidation of toluene. It was shown that well-formed perovskite structures were obtained over samples LMO-SG and LMO-GC. Traces of La2O3 phase were detected over sample LMO-CP. The ranking in terms of specific surface area, low-temperature reducibility and concentration of surface adsorbed oxygen species from the highest to the lowest value was LMO-SG>LMO-CP>LMO-GC, which was in good agreement with the catalytic activity order. Sample LMO-SG exhibited the optimum catalytic activity and durability without any deactivation observed during the steady state of 60h. Its superior catalytic performance could be greatly attributed to its higher specific surface area, better low-temperature reducibility and more available surface adsorbed oxygen species. The apparent activation energies of samples LMO-SG, LMO-GC and LMO-CP were 71, 84 and 76kJmol−1, respectively. The lowest apparent activation energy of sample LMO-SG was in good agreement with its better catalytic behavior for toluene oxidation.

Optimization of Process Conditions on Landfill Leachate Treatment by CWAO Method

the landfill leachate was disposed by Catalytic Wet Air Oxidation (CWAO) method, and the monitoring indexes include CODCr, decolorization and pH. The results showed that the CODCr removal rate and the decolorization rate of landfill leachate increased with the increase of reaction temperature and reaction pressure. However, they first rose then reduced with the increase of catalyst dosage. Under the condition of the catalyst concentration 300 mg/L of Co (NO3)2, at the reaction pressure of 3.5 MPa and the reaction temperature of 180 °C, the CODCr removal rate and the decolorization rate reached 56.8% and 83.7%, respectively, and pH was 8.45 at the reaction time of 90 min.

Influence Factors of Landfill Leachate Treatment with CWAO Method

Landfill Leachate is a kind of organic wastewater with high concentration and non-biochemical character, and Catalytic Wet Air Oxidation (CWAO) is suitable for this kind of wastewater treatment. In this study, Landfill leachate was treated with Catalytic Wet Air Oxidation (CWAO) method. The monitoring indicators consist of CODCr, absorbance, pH and chroma. The results show that: CODCr removal rate and decolorization rate of landfill leachate reduce with the reduction of the influent pH, the increment of water concentration and the extension of the reaction time; Under the optimized operating conditions: the influent pH of 8.10, the influent CODCr of 16611 mg/L, the reaction time of 90 min, the CODCr removal rate and decolorization rate of landfill leachate reach 56.8% and 83.7%, respectively. The effluent pH is 8.33 and chroma is 1600 times.

A new catalytic oxidation method for sensitive quantification of bromate in flours and bottled water using AgNPs

In this paper, a simple and sensitive spectrophotometric method for the determination of nanomolar level of bromate, based on the catalytic effect of silver nanoparticles on the oxidation of acid red 14 by potassium bromate, is described. The reaction rate was monitored spectrophotometrically by measuring the decrease in absorbance of acid red 14 at 516nm. The detection limit of the method was 8ng/mL, and the linear range was between 15 and 130ng/mL. The effects of acidity, concentration of reactants and reaction time, and external ions were also discussed. The optimum reaction conditions were fixed, and some kinetic parameters determined. The relative standard deviation for the determination of bromate at the concentration of 50ng/mL was calculated to be 0.996% (n = 10). The method has been successfully applied to the determination of bromate in flours and bottled waters.

Preparation of poly ferric sulfate and the application in micro-polluted raw water treatment

Poly ferric sulfate (PFS) is a kind of polymeric coagulants widely used in China in the past 20 years and reveals certain advantages in advanced treatment of wastewater. In this paper, three samples were synthesized by different methods: sodium nitrite catalytic oxidation method (PFS-1), one-step method (PFS-2) and nitric acid oxidation method (PFS-3). The raw material for PFS-3 was the by-product of (NH4)2SO4 manufacturing, which makes this method conducive to the full utilization of resources. The products were characterized by scanning electron microscopy and Fourier transformed infrared spectroscopy. Their coagulation performances in micro-polluted raw water treatment have been evaluated by jar tests. When the coagulation dosage was 0.1 mmol L−1 as Fe, the turbidity removal rate was around 84% and the removal rate of natural organic matter (NOM) was 35%–40%. The water treated by PFS was much closer to neutral but fluctuated from 7.9 to 7.2 at dosages of 0.05–0.3 mmol L−1 as Fe, which showed similar pe...

Solid waste decontamination by thermal desorption and catalytic oxidation methods

AbstractCombined thermal desorption and catalytic oxidation for soil decontamination was studied at the pilot plant scale. Gasoline, xylene, and 2-methylnaphthalene were used as model contaminants in the concentrations from 2 g to 10 g per kg of soil. To guarantee the flow of the exhaust gas from the thermal desorption unit into the catalytic oxidation unit, a Venturi pump was used. Based on the laboratory scale catalytic tests, the commercial catalyst EnviCat® VOC-1544 was employed in the catalytic oxidation. Residual concentrations of hydrocarbons in soil after the thermal desorption were below the detection limits of the applied analytical method (GC-MS). Although the contaminant concentrations at the inlet of the catalytic reactor significantly varied during the experiments, the efficiency of catalytic oxidation was higher than 90 % in all cases.

Direct Compression of Cellulose and Lignin Isolated by a New Catalytic Treatment

Tablet compression of softwood cellulose and lignin prepared by a new catalytic oxidation and acid precipitation method were investigated and compared with the established pharmaceutical direct compression excipients. Catalytic pretreated softwood cellulose (CPSC) and lignin (CPSL) were isolated from pine wood (Pinus sylvestris). The compaction studies were carried out with an instrumented eccentric tablet machine. The plasticity and elasticity of the materials under compression were evaluated using force-displacement treatment and by determining characteristic plasticity (PF) and elasticity (EF) factors. With all biomaterials studied, the PF under compression decreased exponentially as the compression force increased. The compression force applied in tablet compression did not significantly affect the elasticity of CPSC and microcrystalline cellulose (MCC) while the EF values for softwood lignins increased as compression force increased. CPSL was clearly a less plastically deforming and less compactable material than the two celluloses (CPSC and MCC) and hardwood lignin. CPSL presented deformation and compaction behaviour almost identical to that of lactose monohydrate. In conclusion, the direct tablet compression behaviour of native lignins and celluloses can greatly differ from each other depending on the source and isolation method used.

Synthesis of novel CeO2 microspheres with enhanced solar light photocatalyic properties

In this communication, CeO2 microspheres have been firstly synthesized via a facile catalytic oxidation method under room temperature. The morphology and structure of the synthesized material were characterized by FESEM and XRD, respectively. The synthesis mechanism could be attributed to the catalysis of Ag+ in the reaction system. The synthesized material exhibited good photocatalytic activity for the degradation of acid orange 7 (AO 7) under solar light irradiation, and the pseudo-first order reaction rate constant (k) of 0.005min−1 for CeO2 microspheres is higher than 0.002min−1 of commercial TiO2 P25. The synthesized material could be useful as a solar-light-driven photocatalyst for decomposing organic compounds.

Research on Impregnated Ruthenium Catalyst of Simulation Printing and Dyeing Wastewater Treatment with CWAO Method

In the treatment of methyl orange simulation printing and dyeing wastewater by catalytic wet air oxidation method, the Ru series catalysts were prepared with the equal amount impregnation method. The catalyst activity and stability were characterized by the decolorization rate of the water samples, and the eluted metal ion concentration from the catalyst of the water samples. XRD, SEM, FT-IR were used to characterize the catalysts. The results showed that: when active allocation ratio of the catalyst was Ru:Cu:Fe:Ce:La = 1:0.5:0.5:0.5:0.5, the degradation rate of methyl orange could reach up to 98.5%. And the concentration of each metal component eluted lower after the reaction, while its activity and stability were relatively high.The active component of 1wt% Ru catalyst mainly existed as the form of γ-Al2O3, RuO2, La2O3, La2CuO4 and CeO2. The surface of catalyst was relatively flat and flaky. The Ru catalyst appeared strong infrared absorption in the vicinity of 1070 cm-1, 1650 cm-1 and 3450 cm-1.

Effects of PVP on the preparation of nanosized Al2O3 supported Ni catalysts by polyol method for catalytic partial oxidation of methane

Small Ni metal nanoparticles (<10nm) supported on γ-Al2O3 were prepared by a simple polyol method in ethylene glycol (EG) medium. The effects of PVP (polyvinylpyrrolidone) ratio on the crystallite and particle sizes were determined by XRD and TEM analysis. The activities of the catalysts were evaluated for partial oxidation of methane (CPOM). The results indicated that in polyol process varying the ratio of PVP resulted in smaller Ni crystallite sizes, good metal dispersion and high catalytic activity. When the weight ratio of PVP to metal salt increased from 0:1 to 5:1 in the as-prepared catalyst the particle sizes decreased from 13.10nm to 8.0nm, and methane conversion increased from 69.40% to 92.00% at 800°C. The activity of the catalysts in CPOM reaction also depended on the thermal treatment. H2-pretreated catalysts exhibited higher activity than non pre- treated catalyst, suggesting that the presence of organic matrix hinders the access to the nickel active sites. Among the catalysts tested, Ni/γ-Al2O3 catalyst with a weight ratio of PVP to metal salt 5:1 exhibited the higher activity (92%) and stability with a gas hour space velocity of 157,500 (Lkg−1 h−1) at 800°C.

Catalytic Oxidation Activity of NO on TiO&lt;sub&gt;2&lt;/sub&gt;-Supported Mn-Co Composite Oxide Catalysts

Globally, NOx is one of the most widespread pollutants. It is generated mainly from the burning of fossil fuels, and NO is very difficult to remove because of its capacity to be dissolved in water. The catalytic oxidation method can be used to convert NO to NO2, which is soluble in water and can be removed using desulfurization devices. Here, a series of TiO2-supported Mn-Co composite oxide catalysts were prepared using the impregnation method. The results of catalytic activity tests showed that the addition of Mn enhanced the efficiency of NO oxidation. Significantly, with 6% doping amounts, Mn (0.3)-Co(0.7)/TiO2 showed the best activity of 88% NO conversion at 300 degrees C. X-ray diffraction (XRD), N-2 adsorption/desorption, hydrogen temperature-programmed reduction (H-2-TPR), oxygen temperature-programmed desorption (O-2-TPD), and in-situ diffuse reflectance Fourier transform infrared (in-situ DRFTIR) spectroscopy were used to characterize the catalysts. The results indicated that when the doping amount was 6%, the Mn enhanced the specific surface areas and pore volumes, which improved the dispersion of the active component over the TiO2 support. The co-doping of manganese into the Co/TiO2 also enhanced the oxygen desorption capabilities of the catalysts, which improved their reduction abilities. In addition, bridge NO3-, the key intermediate, was converted into NO2; this conversion was also enhanced by the presence of Mn on the Co/TiO2 catalyst. All of the above reasons account for the high NO catalytic oxidation activity of the supported Mn-Co composite oxide catalysts.