[Objective] With the popularization of co-combustion of high-alkali coal in Xinjiang

systematic studies on the difference and mechanism of alkali metal poisoning resistance between honeycomb and plate SCR catalysts remain insufficient. Most existing researches are based on the simulation of single alkali metal salts in the laboratory

whereas actual fly ash constitutes a complex mixture. The significant discrepancy between simulated conditions and real flue gas from high-alkali coal combustion results in limited engineering guidance value of relevant research findings. [Methods] In this work

actual fly ash from power plants was adopted

and typical flue gas conditions were simulated in a laboratory fixed-bed reactor. The physical and chemical property changes of fresh and aged honeycomb and plate SCR catalysts were compared. Combined with specific surface area measurement

NH3-TPD analysis of surface acidity

XPS characterization of vanadium valence states and other techniques

the deactivation behaviors of the two catalysts upon alkali metal poisoning were systematically investigated. [Results] Although plate catalysts are more susceptible to sintering deactivation under extreme high-alkali conditions

and bulk diffusion deactivation is difficult to recover via physical or mild chemical regeneration

their denitrification efficiency decays more slowly than that of honeycomb catalysts. At the same alkali loading

the denitrification activity of honeycomb catalysts decreased by 29.5% within 4 800 hours

while that of plate catalysts only dropped by 24.6%. The vanadium valence cycle of honeycomb catalysts is more easily interrupted by alkali metals

which suppresses the “fast SCR pathway” relying on NO→NO2 conversion. Moreover

their Brønsted acid sites are more prone to neutralization by alkali metals. [Conclusion] Therefore

plate catalysts are the preferred choice for longterm denitrification in industrial scenarios involving co-combustion of high-alkali coal.