SELECTIVE CATALYTIC REDUCTION OF NITRIC OXIDE WITH AMMONIA OVER SILICA-SUPPORTED VANADIUM OXIDE CATALYST

Abstract

The selective catalytic reduction (SCR) of nitric oxide with excess ammonia in the presence of oxygen on silica-supported vanadium oxide catalyst was studied in a packed-bed reactor, and a mathematical model was proposed for the processes occurring in the reactor. Experimental data were presented for evaluation of the accuracy of the proposed model. Good agreement was observed between the measured and calculated values of the conversion in the outlet of the reactor. Once the validity of the proposed model was verified, it was used to examine the effects of different parameters such as feed temperature, inlet feed composition, and gas hourly space velocity (GHSV) on the conversion of NO over V₂O₅/SiO₂ catalyst for practical application. The results for the employed catalyst showed that high NO conversion occurred at temperatures of 280°–300°C, GHSV less than 2000 h⁻¹ (STP), and O₂ concentration greater than 10% v/v. These results clearly demonstrate the high potential for this catalyst to be applied commercially for the control of NO_x emissions from flue gases of different sources.

Keywords:

• Ammonia
• Mathematical model
• Nitric oxide
• Packed-bed reactor
• Selective catalytic reduction (SCR)
• V₂O₅/SiO₂ catalyst

Acknowledgment

This work was financially supported by Petrochemical Research & Technology Company of National Iranian Petrochemical Company, whose support is acknowledged by the authors.

Notes

^aHydrothermal synthesis co-exchanged zeolite for SCR-NO with propane.

^bComposition: 72–80% SiO₂, 17–22% Al₂O₅, 1–4%Fe₂O₃, <1.5% K₂O.

^cWash-coated co-exchanged zeolite for SCR-NO with propane.

^dCatalyst in the shape of honeycomb.

^eFor the bed height of 30 cm.

^fAC: activated carbon; catalyst in the shape of honeycomb.