Papers by Keyword: Catalytic Oxidation

Abstract: In this research, Fe_xO_y/C was first prepared through one-step pyrolysis of FeCl₃-coffee husk mixture. The surface of Fe_xO_y/C was then loaded with Ag particles using an ex-situ method, producing Ag-Fe_xO_y/C. XRD result indicates that different crystals of Fe₃O₄, Fe₂O_3, and FeO(OH) were formed on the surface of porous carbon. The existence of 0.41 wt% Ag and 3.13 wt% Fe was determined by AAS results. Subsequently, Ag-Fe_xO_y/C was primarily explored for its antibacterial and catalytic applications. According to the ASTM E2149-13a standard, the material killed 62% of Staphylococcus aureus within 60 min of contamination. For catalytic performance, 50 ppm sunset yellow FCF was decolorized by 240 ppm H₂O₂ using 0.40 g/L Ag-Fe_xO_y/C at pH 3.0. The results showed that Ag-Fe_xO_y/C had an adsorption capacity of 7.8 mg/g and an average decolorization rate of 41.6 mg.g^-1.h^-1. This rate was approximately 13-fold higher than that without a catalyst. Furthermore, Ag-Fe_xO_y/C with a saturation magnetization of 3.62 emu/g was separated and recovered easily from the treated mixture by a magnet bar. Overall, the findings initially prove that Ag-Fe_xO_y/C is a promisingly multifunctional material, thanks to its antibacterial activity, adsorption capacity, catalytic activity and magnetic recoverability.

Abstract: In order to explore an efficient and rapid method for treating typical volatile organic compounds (VOCs), benzene, as a HYPERLINK "javascript:void (0)" representative of VOCs, was catalytically oxidized by hopcalite under microwave irradiation. The decontamination performance under different conditions was studied, and the influences of some factors on the benzene conversion ratio were tested, such as microwave irradiation power, initial benzene concentration, catalyst amount and gas humidity. Results showed that benzene conversion ratio could reach 99.2% under the condition that microwave power, initial benzene concentration, gas flow and catalyst bed height were 70W, 1917mg/m³,1.0L/min, and 3.86cm separately. It is concluded that microwave irradiation can promote the catalytic oxidation of benzene and it has higher energy efficiency than traditional heating.

Abstract: The technology for mercury removal in coal-fired power plant is still under development. In the flue gas, elemental mercury is the main component of mercury, and is hard to be removed due to its high volatility and low solubility. So converting Hg⁰ to Hg²⁺ in or ahead of the FGD is significant to enhance mercury removal. In this work, plasma treatment method was used to prepare V₂O₅/TiO₂ catalysts for effectively oxidation of Hg⁰. Plasma treatment of V₂O₅/TiO₂ resulted in the improvement of mercury oxidation activity. The Hg⁰ oxidation efficiency of the catalysts treated by plasma is over 82% at 300 °C, which is about 30% higher than that of the untreated catalyst. The catalysts were characterized using SEM, BET and EPR. SEM results indicated that plasma treatment can create cracks and small particles on simple surface, however, calcinations cause sintering and agglomeration. The superior catalytic performance is mainly attributed to the formation of particles attached to the catalyst surface, the higher amount of V⁴⁺ ions and vacancies on the catalyst surface.

Abstract: SrTi_1-xMg_xO_3-δ, an oxidation catalyst, is employed to produce active oxygen species in an oxidation furnace and to enhance oxidation of 4H-SiC at low temperatures. The linear rate constant of the oxidation model at the 4H-SiC (0001)-Si surface at 800~900 °C is enhanced by two orders of magnitude in comparison to the conventional dry oxidation. The catalytic oxidation is, therefore, able to for a gate oxide at temperatures as low as 800°C. Interface state density in the energy range of 0.2~0.5 eV from the conduction band edge of the 4H-SiC oxidized with catalyst at 800°C is almost same as the one oxidized using the conventional dry oxidation at 1100 °C.

Abstract: A series of manganese oxides (Me-OL-1s, Me: Mg, Fe, Ni and Cu) were synthesized by static hydrothermal and ion-exchange method. The as-prepared samples were characterized by means of X-ray diffraction (XRD), Raman spectroscopy (Raman) and Scanning electron microscope (SEM). The catalytic activity of the Me-OL-1 samples for the formaldehyde degradation was investigated at room temperature. The synthetic Me-OL-1s belong to birnessite-type manganese oxides. All the Me-OL-1 catalysts show the activity for the catalytic oxidation of formaldehyde at room temperature and exhibit the activity order of Fe-OL-1 > Ni-OL-1 > Cu-OL-1 > Mg-OL-1. The removal rates of formaldehyde are increased with increasing contact time.

Abstract: A series of highly dispersed ionic liquid catalysts were used for the oxidation desulfurization of dibenzothiophene (DBT) in model oil in the presence of H₂O₂. The effects of the loading of [BMIM]HSO₄ immobilized, reaction time, temperature, O/S molar ratio and the dosage of catalysts on DBT removal were investigated in detail. The catalyst with the loading of [BMIM]HSO₄ was 25% exhibited the highest activity. The DBT removal of model oil can reach 99.9% in 5 h at 60 °C, O/S molar ratio of 10, V_{model oil}=10mL, m_catalysts=2.00g. The catalysts can be easily recycled and can be recycled 2 times without a significant decrease in activity.

Abstract: The manganese oxide (MnO₂) sample was synthesized by the reaction of KMnO₄ with Mn (Ac)₂ using the HNO₃ solution as pH regulator. The Ag-doped manganese oxide, Ag/MnO₂-Q and Ag/MnO₂-H, were synthesized by incorporation method and typical wet impregnation method, respectively. The structure of catalysts was characterized by N₂ adsorption/desorption and X-ray diffraction. The influences of preparation methods on the catalytic activity of CO oxidation were studied. The doping of Ag to MnO₂ decreased the specific surface area of Ag/MnO₂ catalysts, especially for Ag/MnO₂-H samples prepared by traditional wet-impregnation method. The Ag/MnO₂ catalysts showed higher catalytic activity for CO oxidation than that of MnO₂. The catalytic activities of Ag/MnO₂ samples strongly depended upon the preparing methods, among which 3Ag/MnO₂-Q catalyst, prepared by the incorporation method, was the most efficient catalyst towards the addressed reactions. The excellent performance of 3Ag/MnO₂-Q was mainly associated with the good low-temperature reducibility, abundant surface oxygen and broadly dispersed silver oxides species.

Abstract: The size controlled colloidal gold nanoparticles were prepared by sodium citrate photochemical system. The size and morphology of the gold nanoparticles were characterized by TEM and UV-Vis spectroscopy. nanoAu/C catalysts were obtained by loading the gold nanoparticles. The catalysts were used for the catalytic oxidation reaction of glyoxal and glucose in liquid phase. The research results showed that the catalysts had higher catalytic activity, and this preparation method is successful.

Abstract: . New developments in green catalytic oxidations of alcohols with H₂O₂ as oxidant in last decade are reviewed. Emphasis is placed on introducing the heterogeneous catalysts supported on different material in various of reactions, mechanism features are discussed as well.

Abstract: Pharmaceutical wastewater was treated by coupling of micro-electrolysis-catalytic oxidation, using porous multicomponent alloys as packing. Influence of initial pH of wastewater, micro electrolysis time, packing ration, H₂O₂ dosage and catalytic oxidation time on removal rate of COD in wastewater was studied. The optimal process condition for treatment of pharmaceutical wastewater by coupling of micro-electrolysis-catalytic oxidation is as follows: initial pH 2.5, micro electrolysis time 90 min, packing ration 1:1, and dosage of H₂O₂ 2 ‰, catalytic oxidation time 120min and oxygen aeration. Under the optimal process condition, the average removal of COD is 52.5%, and the average mass concentration of COD is 276 mg/L.