Teruyuki Hakoda

Oxidation of xylene and its irradiation byproducts using an electron-beam irradiating a γ-Al2O3 bed

The oxidation of xylene and its irradiation byproducts in air using a γ-Al2O3 bed was studied under electron-beam (EB) irradiation to enhance the decomposition of volatile organic compounds in ventilation gases emitted from paint factories. The EB irradiation experiments were mainly conducted under three different conditions: in the absence of a γ-Al2O3 bed, and in the presence of a γ-Al2O3 bed placed in an irradiation or a non-irradiation space. The use of the γ-Al2O3 bed enhanced the oxidation of the irradiation byproducts to CO2. Furthermore, the oxidation of the byproducts was accelerated by the placement of the γ-Al2O3 bed in the irradiation space, because of the interaction of primary electrons with the surface of the γ-Al2O3 pellets. This combined oxidation process enabled a reduction in the energy consumption for non-toxic CO2 formation and improved the selectivity of CO2 production.

Oxidation Process of Xylene in Air Using

Oxidation of xylene and its irradiation-induced organic by-products in air using Ag-loaded TiO₂(Ag/TiO₂) beds was studied under electron beam (EB) irradiation. The Ag/TiO₂ beds were placed in an irradiation or a nonirradiation space in order to distinguish the oxidation of xylene and its by-products by EB irradiation, a catalytic process, and a combination of the two. The oxidation reactions on the surface of the Ag/TiO₂ pellets were also distinguished based on the difference in the concentrations of xylene, CO₂, and CO in the presence of the Ag/TiO₂ bed or a noncatalyst (stainless-steel pellets) bed with the same occupation volume. Placement of the Ag/TiO₂ bed in the irradiation space resulted in the suppression of xylene decomposition, because xylene was decomposed exclusively in the gas phase regardless of the presence of the Ag/TiO₂ bed. On the other hand, production of CO₂ was observed in the gas phase of the irradiation space and on the surface of the Ag/TiO₂ pellets in both the irradiation and nonirradiation spaces. The concentration of CO₂ produced in the gas phase and on the Ag/TiO₂ pellet surface increased when the layer was placed in the nonirradiation space (near the irradiation space). CO₂ production was enhanced by loading Ag over the TiO₂ pellet surface. The highest concentration of CO₂ was obtained for Ag/TiO₂ with Ag content greater than 5 wt%. The production of CO₂ from the by-products on the Ag/TiO₂ pellet surface was evaluated from the difference in the concentrations of xylene and its by-products between the Ag/TiO₂ and noncatalyst beds.

\hbox{Ag/TiO}_{2}

Platinum (Pt) nanoparticles were prepared on a glassy carbon plate by a sputtering method and then irradiated with proton (H + ) beams at energies of 0.38 and 10 MeV at room temperature. Cyclic voltammetry in an aqueous 0.5 mol/dm 3 H 2 SO 4 solution suggested that the lower-energy beam irradiation enhanced the active surface area of the Pt nanoparticles, calculated from the coulombic charge for hydrogen desorption. Thus, the nanoparticles would be modified by H + beam-induced electronic excitation so that they have higher surface activity. The mechanism of this irradiation effect seems to be rather complicated and is still unclear at present, but we may discuss it in relation to a change in the interfacial crystal structure during the irradiation.

Under Electron Beam Irradiation

Oxidation of xylene and its organic irradiation byproducts in air using plasma-driven catalyst (PDC: TiO2 and Ag/TiO2) pellet layers was studied under electron beam (EB) irradiation. The layers were placed in an irradiation or a non- irradiation space in order to distinguish the oxidation of xylene/byproducts by EB irradiation, by catalytic process, and by a combination of the two. The oxidation reactions on the surface of the PDC pellets were also extracted by means of the difference in the concentrations of xylene and byproducts in the presence of the PDC layer or a non-catalyst (stainless-steel) layer with the same volume. For irradiated xylene/air mixtures, xylene was exclusively decomposed in the gas phase in an irradiation space. Introduction of the PDC layer to an irradiation space resulted in the suppression of xylene decomposition. On the other hand, production of CO2 was observed in the gas phase of an irradiation space and on the surface of the PDC pellets placed in irradiation and non-irradiation spaces. The concentration of CO2, produced in the gas phase and on the PDC pellet surface, became higher when the layer was placed in the vicinity of an irradiation space. The production of CO2 is enhanced by loading of Ag to the TiO2 pellet surface. The highest concentration of CO2 was obtained for Ag/TiO2 with Ag contents greater than 5wt%. The production of CO2 from byproducts on the PDC pellet surface was evaluated from the difference in the concentrations of xylene and byproducts between the PDC and the SUS pellet layers.