SCR of NO by C3H6 over Cu-Fe-PILC in the presence of oxygen and steam
Advancing the chemical engineering fundamentals
Catalysis (T2-13P)
Keywords: Fe-PILC, Copper, SCR, water
Pillared clays have been extensively studied as catalysts for NOx reduction with ammonia [1] and hydrocarbons [2]. Long and Yang [2] found that Fe3+-exchanged Ti-PILCs showed very high activities for the SCR of NO by NH3 in the presence of excess oxygen, and that the presence of H2O and SO2 increased the activity at high temperatures. In a previous work [2], we studied the SCR of NO by propene over Cu-ion-exchanged Fe-PILCs prepared with different pH conditions. Samples prepared under alkaline pH showed the highest NO conversion. It was also observed that the presence of CuO species led to an improvement in NO yield to nitrogen. The aim of the present work is to study the catalytic activity of the Cu-Fe-PILC for the HC-SCR of NO in the presence of oxygen and steam.
The addition of 10% water to the reactant mixture led to an appreciable decrease in NO conversion for all the samples prepared in this work. The SCR of NO inhibition is due to a new competition between NO, propene and water for the same active sites on the catalyst. NO and propene conversions were tested under wet conditions at constant temperature for 48 h. No significant changes of catalyst activity were observed, so that the catalysts seem to be stable for this time on stream. N2 adsorption experiments were carried out after reaction under wet conditions to check that the catalyst structure was not altered by metal sintering or pillar collapse of the Fe-PILC. The reversibility of catalysts activity was also studied. Thus, water was removed from the reactant mixture. It was observed that deactivation due to water was fully reversible. For instance, under dry conditions at 260 ºC, NO conversion was about 55%. Then, water was fed, and NO conversion dropped to 40%. After switching again from wet to dry conditions, NO conversion was restored to 55%.
References
[1] Long, R.Q.; Yang, R. T. Selective Catalytic Reduction of Nitrogen Oxides by Ammonia over Fe3+-Exchanged TiO2-Pillared Clay Catalysts. J. Catal. 186 (1999) 254-268.
[2] Dorado, F.; de Lucas, A.; García, P.B.; Valverde, J.L.; Romero, A. Preparation of Cu-ion-exchanged Fe-PILCs for the SCR of NO by propene. Appl. Catal. B: Env. 65 (2006) 175- 184.
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Presented Wednesday 19, 13:30 to 15:00, in session Catalysis (T2-13P).
