Nitrogen oxides reduction by carbon monoxide over semi-coke supported catalysts in a simulated rotary reactor: reaction performance under dry conditions

Abstract

A novel rotary reactor was proposed for nitrogen oxides (NO x ) reduction by carbon monoxides (CO) in order to avoid the oxygen inhibition effect. NO x adsorption and reduction were separated into two different zones in the proposed rotary reactor. NO x in the flue gas was adsorbed onto the catalyst surface in the adsorption zone and then reduced by the reducing gas in the reduction zone. The performance of the proposed reaction process was investigated in a simulated rotary reactor. The catalysts used were lab synthesized, Fe and Co co-impregnated over activated semi-coke. The results showed an excellent NO x removal efficiency at 200 and 250℃. However, the NO x reduction efficiencies were always much lower than the removal efficiency. Most of the removed NO x was simply passed from the flue gas to the reducing gas. It is very important to feed great excess CO in the reduction zone, since CO tended to be firstly consumed by residue oxygen in the reduction zone and then be involved in the NO+CO reaction. In an in situ DRIFTs study of the dynamic NO x adsorptionreduction process, it was found that poor reduction and desorption behavior of the store nitrates was the bottleneck of the NO x adsorption-reduction process.

NOx reduction by CO over ASC catalysts in a simulated rotary reactor: effect of CO2, H2O and SO2

“…11(a), a broad band of nitrate species at around 1391 cm À1 could be observed, and the NO + CO reaction was vigorous, which was matched with the previous study. 5 However, aer adding 15% CO 2 into the gas streaming (in Fig. 11(b)), the band of nitrate species at around 1391 cm À1 increased, and two dominant bands of gaseous CO 2 at 2336 and 2362 cm À1 appeared, indicating that the degree of the NO + CO reaction decreased.…”

“…In addition, oxygen concentration is the basis for distinguishing between the adsorption stage and the reduction stage. 5 3.3.1 Effect of CO 2 on the NO x adsorption and reduction. The real reducing gas can be provided by the coke making process of the power plant, so the real reducing gas may contain high concentration of CO 2 .…”

“…8 shows the in situ DRIFT results of NO, O 2 and CO 2 co-adsorption on the catalyst surface as the temperature changed from 50 C to 350 C. Several big peaks could be observed between 600 and 2500 cm À1 . Two dominant bands at 2336 and 2362 cm À1 were assigned to gaseous CO 2 , 5,27 indicating that most of the carbon dioxide was stored on the catalyst surface in physical adsorption way. With the increase of temperature, these two peaks decreased gradually, which indicated that the physisorbed CO 2 on the catalysts was unstable and easy to be desorbed by increasing temperature.…”

“…5) had an obvious change with the temperature. When the temperature was increased from 50 C to 350 C, this band tended to be narrower and lower, meanwhile, the band of cis-N 2 O 2 2À at 833 cm À1 was hardly observed at all tested temperature.…”

Investigation of SO2tolerance of Ce-modified activated semi-coke based catalysts for the NO + CO reaction

“…In recent years, researchers have begun to focus on investigations such as these. [9][10][11][12] However, the application of the new processes has faced some difficulties: one is that the presence of O 2 will consume the majority of the reductant. [10][11][12] Therefore, in consideration of the negative effects of O 2 , the NO x adsorptionreduction process (model reactor in Fig.…”