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The abatement of dilute p-xylene (500 ppm) from a contaminated air stream (2 L min−1) by the non-thermal plasma in combination with an ozone decomposing catalyst (pelleted Mn/γ-Al2O3) was investigated. The reactor performance was evaluated in terms of p-xylene conversion, CO x selectivity and ozone emission with and without external heating. Generally, the removal of p-xylene gradually increased with increasing the applied voltage from 16 to 22 kV (peak height). As the catalyst was used (i.e., packed inside the plasma active region), the reactor was able to remove ca. 82% of p-xylene at 22 kV, compared to 54% done by plasma alone. Under the same plasma-catalytic condition, the removal of p-xylene was successfully achieved (ca. 96%) by heating up the reactor to 150 °C. Not only was the conversion improved, but also the mineralization of p-xylene was also enhanced considerably by the mild thermal heating, increasing the CO2 selectivity from ca. 41 to 59%. The ozone emission measurement showed that ozone formed in plasma was readily catalytically decomposed on Mn/γ-Al2O3 at above 16 kV, even without external heating. As revealed by the reactor infrared thermographic images, the plasma-induced surface temperature of the catalyst was far higher than the external heating temperature (i.e., 150 °C), facilitating the catalytic degradation of ozone and reducing the formation of byproducts. Additionally, no organic compounds have been found on the spent catalyst, avoiding the possibility of catalyst deactivation during the course of experiment.

Combined removal of n-heptane and CO using a catalytic reactor coupled with dielectric barrier discharge plasma was investigated over several metal oxide catalysts including bare γ-Al 2 O 3 , Ag 2 O/γ-Al 2 O 3 , MnO/γ-Al 2 O 3 , RuO 2 /γ-Al 2 O 3 and PdO/γ-Al 2 O 3 . In order to effectively utilize the heat generated during plasma discharge for enhancing catalytic reactions, the plasma-catalytic reactor was thermally insulated by covering it with a glass wool jacket. Plasma propagated radially outward from the central high-voltage electrode with gradually increasing the applied voltage, and the temperature decreased with the radial distance due to the decreased plasma intensity, exhibiting a volcanic temperature distribution. The increased reactor temperature could improve the removal of CO and the selectivity toward CO 2 . The results obtained from separate experiments of n-heptane and CO removal showed that the PdO/γ-Al 2 O 3 was the best for the simultaneous removal purpose. The effects of specific input energy ( SIE ), oxygen content, reaction temperature and PdO loading on the simultaneous removal of n-heptane and CO and the formation of byproducts were examined. The removal efficiencies of n-heptane obtained with different catalysts were similar to one another, whereas the removal of CO strongly depended on the type of catalyst. The catalytic activity for the oxidation of CO followed the order: MnO/γ-Al 2 O 3 2 O/γ-Al 2 O 3 2 /γ-Al 2 O 3 2 O 3 . In the present plasma-catalytic hybrid reactor, the mixture of n-heptane and CO was mainly converted into CO 2 , and under an optimized condition, the selectivity toward CO 2 reached 100%.

A red nitride phosphor with a chemical formula: ( Sr 0 . 8 Ca 0 . 2 ) AlSiN 3 :Eu 0 . 0075 2 + was successfully synthesized using spark plasma sintering at a temperature of 1680 °C from powder mixture of metal nitrides of Sr, Ca, Al, and Si and europium (III) oxide. The prepared phosphor showed a wide excitation band ranging from 300 to 550 nm and a broad emission band centered at a wavelength of about 618 nm, being suitable for use in down-conversion white LEDs. The effects of sintering temperature, holding time as well as uniaxial pressure on phosphor characteristics were investigated. Increasing the sintering temperature increased the crystallization and PL characteristics of the phosphor. The excitation and emission intensity of the phosphor was also affected by the holding time at the maximum temperature. When the synthesis was carried out at 1680 °C and 30 MPa, the optimal holding time was around 30 min. Increasing the uniaxial pressure resulted in the improvement of the excitation and emission intensity. The optical properties of the phosphor synthesized at an increased uniaxial pressure of 42 MPa (1680 °C for 30 min) was comparable to those of the commercial phosphor. The experimental results indicated that the spark plasma sintering method is a viable method to prepare nitride phosphors at relatively low temperatures in short synthesis time, compared to conventional methods.