CeO2–WO3 Mixed Oxides for the Selective Catalytic Reduction of NO x by NH3 Over a Wide Temperature Range

Abstract

A series of cerium-tungsten oxide catalysts was prepared by the co-precipitation method and was evaluated for the selective catalytic reduction of NO x by ammonia (NH 3 -SCR) over a wide temperature range. These catalysts were characterized by BET, XRD, XPS and H 2 -TPR analyses. The experimental studies demonstrated that, among cerium-tungsten oxides, CeO 2 -WO 3 with a Ce/W molar ratio of 3/2 exhibited the best activity toward NH 3 -SCR reactions, N 2 selectivity and SO 2 durability over a broad temperature range of 175-500°C at a space velocity of 47,000 h -1 . The strong interaction between Ce and W could be the main factor leading to the high activity of the CeO 2 -WO 3 mixed oxide catalyst.

N2O formation in the selective catalytic reduction of NOx with NH3 on a CeMoOx catalyst

“…Due to the advantages of high oxygen storage capacity, good sulfur-resistance and excellent redox properties, CeO 2 -based catalysts have received great attention for application in NH 3 -SCR reaction [12][13][14][15][16][17][18][19][20]. Recently, a novel CeMoOx catalyst with high NOx removal performance was reported by Peng et al [21] as well as by Li and Li [22].…”

Effect of the calcination temperature on the performance of a CeMoOx catalyst in the selective catalytic reduction of NOx with ammonia

“…A number of CeO 2 based catalysts, such as MnOx-CeOx [7,8], CeO 2 /TiO 2 [9], CeO 2 /TiO 2 [ 10,11], CeOx/WOx [12,13], Ce-P-O [14], CeO 2 /carbon nanotubes [15], CeO 2 -ZrO 2 -NiO-SO 4 2− [16,17] and sulfated CeO 2 [ 18,19], have shown good NH 3 -SCR performance. Qi and Yang [7] reported a MnOx-CeOx catalyst with around 100% NO conversion between 100 and 150 • C at 42,000 h −1 .…”

High-efficiency reduction of NO emission from diesel exhaust using a CeWO catalyst

“…Various catalysts have been reported to be effective for NH 3 /urea-SCR, including vanadium-based catalysts [5], Fe-, Cu-, Ce-exchanged zeolite materials [4,[6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21], and various vanadium-free oxide catalysts [22][23][24][25][26][27][28]. The toxicity of active vanadium species, together with the low stability at high temperatures, has restrained the wide application of vanadium-based catalysts, while the activities of vanadiumfree oxide catalysts are often insufficient and mainly tested using simulating gas in laboratory.…”