SO₂-Induced Alkali Resistance of FeVO₄/TiO₂ Catalysts for NO_x Reduction

Abstract

Selective catalytic reduction of nitrogen oxides with ammonia (NH3-SCR) is an efficient NO x abatement strategy, but deNO x catalysts suffer from serious deactivation due to the coexistence of multiple poisoning substances such as K, SO2, etc. in the flue gas. It is essential to understand the interaction among various poisons and their effects on NO x abatement. Here, we unexpectedly identified the K migration behavior induced by SO2 over K-poisoned FeVO4/TiO2 catalysts, which led to alkali-poisoning buffering and activity recovery. It has been demonstrated that the K would occupy both redox and acidic sites, which severely reduced the reactivity of FeVO4/TiO2 catalysts. After the sulfuration of the K-poisoned catalyst, SO2 preferred to be combined with the surface K2O, lengthened the K–OFe and K–OV, and thus released the active sites poisoned by K2O, thereby preserving an increase in the activity. As a result, for the K-poisoned catalyst, the conversion of NO x increased from 21 to 97% at 270 °C after the sulfuration process. This work contributes to the understanding of the specific interaction between alkali metals and SO2 on deNO x catalysts and provides a novel strategy for the adaptive use of one poisoning substance to counter another for practical NO x reduction.

Revealing the Promotion Effects of Nb on Alkali Resistance of FeVO4/TiO2 Catalysts for NOx Reduction

“…So far, the research about improving the alkali‐resistance of FeVO 4 /TiO 2 has hardly been reported. Very recently, we just reported that the activity of K‐poisoned FeVO 4 /TiO 2 could be recovered by sulfuration treatment because of the SO 2 ‐induced K migration from active sites [10] . However, this work does not essentially supply a design strategy about improving the alkali‐resistance of the FeVO 4 /TiO 2 .…”

“…NO x causes several pollution issues like haze, ozone, acid rain, among others [4–7] . Nowadays, selective catalytic reduction (SCR) of NO x with ammonia is generally recognized as the most efficient technology for reducing the abatement of NO x [8–10] . The commercial V 2 O 5 ‐WO 3 /TiO 2 catalysts have widespread application in coal‐fired power plants because of the satisfactory SCR activity in temperature of 300–400 °C [11,12] .…”

“…[4][5][6][7] Nowadays, selective catalytic reduction (SCR) of NO x with ammonia is generally recognized as the most efficient technology for reducing the abatement of NO x . [8][9][10] The commercial V 2 O 5 -WO 3 / TiO 2 catalysts have widespread application in coal-fired power plants because of the satisfactory SCR activity in temperature of 300-400 °C. [11,12] However, the commercial V 2 O 5 based catalysts are not efficient for some applications, like steel and cement production, and nonelectrical industries, in which the flue gas temperatures are always below 300 °C.…”

“…Very recently, we just reported that the activity of K-poisoned FeVO 4 /TiO 2 could be recovered by sulfuration treatment because of the SO 2 -induced K migration from active sites. [10] However, this work does not essentially supply a design strategy about improving the alkali-resistance of the FeVO 4 / TiO 2 . Therefore, it is of significance to develop alkali resistant FeVO 4 based catalysts with broad temperature window.…”

Alkali and Heavy Metal Copoisoning Resistant Catalytic Reduction of NOx via Liberating Lewis Acid Sites

“…The catalyst with a molar ratio of Ce/Ti = 1:1 was denoted as CeTiO x , representing the composed oxides of Ce and Ti. The K 2 O (1 wt %, the amount of alkali metal accumulated on catalysts in stream for 600–700 h) and CdO (3 wt %, the comparable amount with As in poisoned industrial SCR catalysts) ,, poisons were loaded on CeTiO x through a wet impregnation method with KNO 3 and Cd­(CH 3 COO) 2 ·2H 2 O precursors. , The alkali metal-poisoned, heavy metal-poisoned, and copoisoned samples were denoted as CeTiO x -K, CeTiO x -Cd, and CeTiO x -K & Cd, respectively. Aiming to study the poisoning resistance of the acid additive, a certain amount of H-ZSM-5 (mass ratios of 10–50 wt % among modified catalysts) was mixed with the CeTiO x catalyst to obtain the modified catalysts.…”