Simultaneous removal of SO2 and NOx from flue gas using a CuO/Al2O3 catalyst sorbentII. Promotion of SCR activity by SO2 at high temperatures

Abstract

Promoting effect of SO 2 on selective catalytic reduction (SCR) of NO by NH 3 over a CuO/Al 2 O 3 catalyst sorbent has been investigated. Transient experiment, X-ray photoelectron spectroscopy (XPS), in situ DRIFT, NH 3 -TPD, and temperature-programmed reduction (TPR) were used to evaluate the promoting mechanism. The results show that the presence of SO 2 in the reaction stream can significantly promote catalytic activity of NO reduction at temperatures above 300 • C due to the formation of sulfate species on the catalyst surface. Sulfate species affect SCR activity by changing the acidity and redox property of the catalyst sorbent. In situ DRIFT shows that only ammonia coordinated on Lewis acid sites is found on the CuO/Al 2 O 3 catalyst sorbent. Sulfation of CuO/Al 2 O 3 catalyst sorbent greatly increases the concentration and strength of Lewis acid sites and the concentration of Brønsted acid sites. However, the ammonia bound to Brønsted acid sites does not play an important role in the SCR reaction in the catalyst system. Moreover, there is a close relationship between the SCR activity and ammonia oxidation activity. Ammonia oxidation experiments and TPR in H 2 suggest that sulfation of the catalyst sorbent weakens the catalyst's oxidation ability and inhibits NH 3 oxidation to NO in the process of SCR, which may be another main promoting effect of SO 2 on SCR.  2004 Elsevier Inc. All rights reserved.

Catalytic reduction of nitric oxide by carbon monoxide over coal gangue hollow ball

“…Al 2 O 3 is active for CO oxidation at temperature higher than 873 K. It is well known that SiO 2 , Al 2 O 3 and TiO 2 have interesting capacities as catalyst support for NO x reduction [9,10], and a series of unitary compounds including TiO 2 , Al 2 O 3 , SiO 2 have been studied as the support of the low temperature SCR catalyst [27][28][29][30][31].…”

Selection of metal oxides in the preparation of rice husk ash (RHA)/CaO sorbent for simultaneous SO2 and NO removal

“…At the moment, there are only a few reports on removal SO 2 and NO simultaneously by the dry method. Some of these reports include: Ca-based sorbent [6,7], Cabased with fly ash [8], natural manganese ore [9], activated carbon [10][11][12], activated carbon-impregnated catalyst [13][14][15] and metal catalyst [16][17][18][19]. Apart from these, the simultaneous removal of SO 2 and NO at low temperature using sorbent prepared from siliceous materials are also very limited, especially using rice husk ash (RHA).…”

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

“…It is generally understood that SO 2 improves SCR activities of CuO/Al 2 O 3 , V 2 O 5 /AC and V 2 O 5 /TiO 2 catalysts [12][13][14]. The above three catalysts, therefore, were subjected to SO 2 treatment, pre-sulfation, which was carried out in a gas stream containing 1700 ppm SO 2 , 5.4 vol% O 2 and about 3% H 2 O at 400°C until the outlet SO 2 concentrations were nearly equal to the inlet values.…”