Deactivation of a vanadia-alumina catalyst for nitric oxide reduction by ammonia

Abstract

The deactivating effect of S02 on the reaction rate of the selective catalytic reduction of NO by NH3 over a vanadia-alumina catalyst was examined. A two-parameter model developed in the companion paper (Nam, I.; Eldrldge, J. W.; Kittrell, J. R. Ind. Eng. Chem. Prod. Res. Dev., preceding paper in this issue) was extended to the analysis of the deactivation data. The activation energies for both fresh and deactivated catalysts were similar. The sulfur content of the catalyst, as well as its surface area, appears to be a dominant deactivation parameter, analogous to coke-induced deactivation. Pore size distribution changes indicate that deactivation In this reaction system involves pore filling and plugging by the deactivating agent. That agent appears to be aluminum sulfate, on the basis of experimental results obtained from thermal gravimetric analyses. An empirical exponential dependence of catalyst activity on the catalyst sulfur content was observed for both primary reactions, NO reduction and NH3 oxidation.

Simultaneous removal of SO2 and NOx from flue gas using a CuO/Al2O3 catalyst sorbentI. Deactivation of SCR activity by SO2 at low temperatures

“…The deactivation effect of SO 2 on NO x removal was also found for other SCR catalysts such as V 2 O 5 /TiO 2 [9], MnO x /Al 2 O 3 [10], V 2 O 5 /Al 2 O 3 [11], CuO/AC [12], V 2 O 5 / AC [13,14], and CuHM [15]. Clearly, surface property change of the support and/or chemical transformation of active sites are important in the determination of NO x removal activity at different temperatures.…”

“…Clearly, surface property change of the support and/or chemical transformation of active sites are important in the determination of NO x removal activity at different temperatures. In the case of V 2 O 5 /Al 2 O 3 [11], formation of aluminum sulfate during SCR reaction in the presence of SO 2 reduces surface area of the catalyst sorbents, which results in severe deactivation of SCR activity. Ammonium (bi)sulfate was also found to form and accumulate on the surface of V 2 O 5 /TiO 2 [9], V 2 O 5 /AC [13,14], and CuHM [15] at temperatures below 280 • C and strongly deactivate SCR activity due to pore filling and/or plugging.…”

Sorption of SO2 and NO from simulated flue gas over rice husk ash (RHA)/CaO/CeO2 sorbent: Evaluation of deactivation kinetic parameters

“…Apart from that, this activation energy for SO 2 sorption at low temperature was also found to be similar as compared to sorbents prepared from various type of CaCO 3 (15.2-19.5 kJ/mol) [27]. For the case of the NO sorption, the value of activation energy was also much lower than previously reported in the literature which include the sorbent prepared from V 2 O 5 /NH 4 Br/TiO 2 /SiO 2 (30.1 kJ/mol) [28], V 2 O 5 -Al 2 O 3 (53.56 kJ/mol) [29] and Fe-ZSM-5 (54 kJ/mol) [30]. However, most of the reported studies for NO sorption were carried out at high temperature processes.…”

Effect of SO2 on a cordierite honeycomb supported CuO catalyst for NO reduction by NH3

“…This indicates that for the sulfated CuO/HC-Al, SO 2 has a little inhibition effect on SCR of NO with NH 3 . Serious or complete deactivation by SO 2 to the SCR reaction was observed on CuO/Al 2 O 3 [15], V 2 O 5 /Al 2 O 3 [11,16] and MnO X /Al 2 O 3 catalysts [10] at temperatures below 300°C, which were attributed to pore plugging resulted from the formation of ammonium (bi)sulfates [11,15] or Al 2 (SO 4 ) 3 [16] or MnSO 4 [10]. However, at 400°C (figure 2), deposition of ammonium (bi)sulfates is not possible.…”