Abstract
In this paper, catalytic samples of 10, 20, 30, 40 and 50% (w/w) urea/activated carbon fibre (AFC), 10% urea-5% La
2
O
3
/ACF, 10% urea-10% La
2
O
3
/ACF, 10% urea-15% La
2
O
3
/ACF, 20% urea-5% La
2
O
3
/ACF, 20% urea-10% La
2
O
3
/ACF, and 20% urea-15% La
2
O
3
/ACF were prepared and used for removal of NO under the condition of: NO, 500 ppm; O
2
, 21%; N
2
, balance, gas space velocity=10000 m
3
·h
−1
·m
−3
, total gas flow = 266.7 mL min
−1
, temperature = 30°C, relative humidity=0%. The physical and chemical properties of the prepared catalysts were characterized by surface area measurements (BET) and scanning electron microscopy studies. Furthermore, the catalytic stability of 10% urea-5% La
2
O
3
/ACF under different concentrations of NO and O
2
were also studied. The results showed that, among the prepared urea/ACF samples, 20% urea/ACF yielded the highest NO conversion at room temperature. Meanwhile, among the prepared urea-La
2
O
3
/ACF catalysts, 10% urea-5% La
2
O
3
/ACF yielded the highest NO conversion. Both 20% urea/ACF and 10% urea-5% La
2
O
3
/ACF could yield over 95% NO conversion at ambient temperature. However, 10% urea-5% La
2
O
3
/ACF had a more stable activity than that of 20% urea/ACF. The catalytic and characterization experimental results, including BET, thermogravimetric analysis and Fourier transform infrared analysis, showed that the NO selective catalytic reduction mechanism of urea-La
2
O
3
/ACF was different from that of ACF and urea/ACF. The NO was purified by ACF mainly by adsorption, whereas there was mainly a reduction reaction when NO was purified by urea/ACF or urea-La
2
O
3
/ACF. ACF-C was not only the catalyst but also the reducing agent for urea/ACF, whereas, for urea-La
2
O
3
/ACF, the catalytic centre was La
2
O
3
, and ACF was mainly the carrier. These differences resulted in the higher and more stable NO removal by 10% urea-5% La
2
O
3
/ACF.