Basic investigation of the chemical deactivation of V2O5/WO3-TiO2 SCR catalysts by potassium, calcium, and phosphate

Abstract

The influence of the combustion products of different lubrication oil additives and impurities in fuel or urea solution on the activity and selectivity of V 2 O 5 /WO 3 -TiO 2 catalysts in the selective catalytic reduction (SCR) of nitrogen oxides by ammonia was investigated. Focusing on the deactivation by calcium, phosphate, and potassium, the DeNO x activity followed the order K)Ca>PO 4 . This trend was investigated on the structural level of the catalyst by means of temperature programmed desorption of ammonia (NH 3 -TPD) and a DRIFT characterization of the adsorbed ammonia species. The results suggest that the studied elements strongly reduce the acidity of the SCR catalyst in the order K ) Ca>PO 4 by mainly affecting the Brønsted acidity of the surface.

Study of the V2O5-WO3/TiO2 Catalyst Synthesized from Waste Catalyst on Selective Catalytic Reduction of NOx by NH3

“…This was mainly caused by the easy formation of ammonium bisulfate with increasing NH3 slip due to the lower NO conversion, and the difficult decomposition of ammonium bisulfate Among all the catalysts, the resynthesized catalyst loaded with 0.5% V 2 O 5 exhibited the poorest activity, even lower than that of the waste catalyst in the temperature range of 150-350 • C. For the resynthesized catalyst containing 1.0% V 2 O 5 , deNO x activity was significantly increased and almost recovered to the level of fresh catalyst. The NO conversion was recovered up to 91% at 300 • C. In comparison, the 1.5% V 2 O 5 -WO 3 /TiO 2 catalyst showed even better deNO x activity at low temperature, with a high NO conversion value of almost 100%, but the conversion decreased markedly at temperature exceeding 400 • C, which was probably caused by the oxidation of NH 3 [8], because the increased N 2 O formation with increasing V 2 O 5 content was also detected simultaneously. The results revealed that the deNO x efficiency (both activity and selectivity) of the resynthesized catalysts with different V 2 O 5 contents varied considerably, and with V 2 O 5 content of 1.0%, the resynthesized catalyst regained a similar activity to the fresh catalyst.…”

“…For the V 2 O 5 -WO 3 /TiO 2 catalyst, anatase TiO 2 acts as a carrier, V 2 O 5 is the active component, and WO 3 performs as the promoter to stabilize the catalyst and prevents the catalyst from sintering. In coal-fired power plants, the SCR catalyst suffers from gradual deactivation during the operation period because of poisoning, sintering, fouling, surface masking, attrition/crushing, and loss of vanadium or change in ratio value of the vanadium in different valence states [3][4][5][6][7][8].…”

Catalysts for the selective catalytic reduction of NOx with NH3 at low temperature

“…For diesel vehicles, fuel and lubrication oil additives as well as urea solutions are the origins of alkali metals. [38][39][40] Accumulation of a small amount of these metals will have a notable poisoning effect on the catalytic activity by decreasing the amount and strength of the Brønsted acid sites. [40][41][42] Periodical washing is also an effective way to regenerate the alkali metal poisoned catalyst, especially for stationary sources.…”

Deactivation and Characterization of SCR Catalysts Used in Municipal Waste Incineration Applications

“…Some are concerned with the stabilization of the ash for use in construction works [8], while others deal with the recovery of, e.g., Zn from the ash [9], tailoring catalyst for simultaneous abatement of polychlorinated dibenzodioxins (PCDD) and NOx [10] or developing a better catalyst for MSWI applications [11]. There is also a vast amount of information on the deactivation of SCR catalysts in general [12][13][14][15][16][17][18][19][20]. Li et al [12] presented a review on the topic in 2016, where they discussed the deactivation and possible regeneration of the catalyst.…”