Effect of Oxygen Concentration in NH3-SCR Reaction over Fe- and Cu-loaded Beta Zeolites

Takamitsu Yasuyuki

Ito Yuuki

Ogawa Hiroshi

Sano Tsuneji

Journal of the Japan Petroleum Institute

The kinetic study on the effect of O-2 concentration in the selective catalytic reduction (SCR) of nitrogen oxide (NOx) by ammonia (NH3) was systematically carried out at temperatures below 200 degrees C over Fe- and Cu-loaded beta zeolites. The large difference was observed in the effect of O-2 concentration over the two catalysts: for the Fe-loaded beta zeolite, the NO conversion increased considerably with the O-2 concentration. On the other hand, for the Cu-loaded beta zeolite, increasing the concentration of O-2 did not have a significant impact. In addition, the temperature dependence of the apparent reaction orders was investigated. The apparent reaction order of O-2 decreased with an increase in the reaction temperature, being 0.9 at 150 degrees C and 0.4 at 200 degrees C for the Fe-loaded beta zeolite, and 0.2 at 125 degrees C and 0.1 at 175 degrees C for the Cu-loaded beta zeolite. The fact that the degree of the reduction in the reaction order of O-2 was consisted with that of the increase in the reaction order of NH3 when the reaction temperature was increased strongly suggests that adsorbed NH3 inhibits the adsorption of O-2.

Ammonia-SCR

Zeolite catalyst

Iron beta zeolite

Copper beta zeolite

Reaction order

Oxygen concentration

Chemistry [ 430 ]

eng

Japan Petroleum Institute

(c) 2012 by The Japan Petroleum Institute

[ISSN] 1346-8804

[DOI] 10.1627/jpi.55.57

[NCID] AA11590615

[DOI] http://dx.doi.org/10.1627/jpi.55.57