Dependence of sintering temperature of BaTiO3 pellets on NOx removal in a packed-bed plasma reactor

The NO/sub x/ removal from air streams has been investigated using a packed-bed plasma reactor. In this study, BaTiO/sub 3/ pellets are prepared at various sintering temperatures by the authors and the effect of sintering temperature of the pellets on NO/sub x/ removal are studied experimentally. The packed-bed plasma is generated by a 25 kHz AC high voltage power supply. Experiments are carried out with 200 ppm NO in dry air and with gas flow rate of 1.0 L/min. As a result, the NO/sub x/ removal is confirmed for the pellets sintered at low temperature up to 600/spl deg/C. In this case, NO/sub x/ removal rate increases with increasing applied voltage until a voltage, and up to 80% of the NO/sub x/ is reduced in dry air. No significant by-product such as N/sub 2/O is observed. While, NO/sub x/ generation is confirmed for the pellets sintered at high temperature. The transition from NO/sub x/ reduction to generation characteristics occurs at the sintering temperature of 800-1000/spl deg/C. X-ray diffraction analysis indicates that the structure of the pellets is mainly constructed by the cubic phase. The dielectric constants of the pellets significantly depend on the sintering temperatures. The specific surface area is 9 m/sup 2//g for the pellets sintered at low temperature and it decreases with increasing the sintering temperature. Consequently, the nonlinear properties of the NO/sub x/ removal are influenced by sintering temperature and have obvious relation with specific dielectric constant and specific surface area.