We investigated the chemical transformation of low concentrations (∼100 ppm) of chlorofluorocarbons (CFCs) in gaseous nitrogen by nonthermal plasma processing by assuming that this transformation occurs by the dominant mechanism of CFC dissociation. The calculated and experimental results indicate that the extent of CFC dissociation induced by energy transfer from electronically excited species is negligible. We suggest that dissociation by impact with high-energy plasma electrons is the process mainly responsible for the decomposition of CFC. We also discuss the possibility of optimizing this plasma process for environmental engineering in the semiconductor industry.
This study is devoted to an investigation of the energy consumption and byproduct generation of the nonthermal plasma-chemical NO-reduction process. Nitrogen gas with a 200 ppm NO impurity has been processed at a pressure of 1.3 atm in a silent discharge reactor with a gap spacing of 50 µm. Detailed measurements of NO, NO 2 and N 2 O concentrations at the reactor outlet were carried out and analysed by means of the created model. On the basis of the proposed three-collision reaction mechanism of N 2 O generation the byproduct-suppression effect has been predicted and experimentally confirmed. An extremely low energy consumption (less than 150 eV per molecule) for NO reduction by the discharge nonthermal plasma has been attained.
We have observed significant enhancements in the rate and capacity of NO2 uptake caused by the injection
of ozone over the zeolite H-ZSM-5, which has a high SiO2/Al2O3 ratio. We performed these experiments
using a gas-flow system in which the profiles of NO2 adsorption and subsequent temperature-programmed
desorption were measured by Fourier transform infrared spectroscopy. We interpret these results in two
ways: either by assuming that fast surface reactions lead to N2O5 formation or by considering that ozone
suppresses the blockage of the reactive Brønsted-acidic protons.
Zeolite. -Ozonization of zeolite H-ZSM-5, which has a high SiO2/Al2O3 ratio, causes significant enhancements in the rate and capacity of NO2 uptake. The adsorption experiments are performed using a gas-flow system in which the profiles of NO2 adsorption and subsequent temperature-programmed desorption were measured by FTIR spectroscopy. The results can be interpreted in two ways, either by assuming that fast surface reactions lead to N2O5 formation or by considering that ozone suppresses the blockage of the reactive Bronsted acid sites. -(GAL*, A.; OGATA, A.; FUTAMURA, S.; MIZUNO, K.; J. Phys. Chem. A 108 (2004) 34, 7003-7008; Natl. Inst. Adv. Ind. Sci. Technol., Ibaraki, Tsukuba 305, Japan; Eng.) -Schramke 43-016
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