Uncovering the centrality of mono-dentate SO32-/SO42- modifiers grafted on a metal vanadate in accelerating wet NOX reduction and poison pyrolysis

Abstract

NOX rarely binds with labile oxygens of catalytic solids, whose Lewis acidic (LA) species possess higher binding strengths with NH3 (ENH3) and H2O than Brönsted acidic counterparts (BA--H+; -OH), oftentimes leading to elevate energy barrier (EBARRIER) and weaken H2O tolerance, respectively. These limit NH3-assisted wet NOX reduction via Langmuir-Hinshelwood-type or Eley-Rideal (ER)-type model on LA species, while leaving ER-type analogue on BA--H+ species proper to reduce wet NOX. Given hard-to-regulate strength/amount of -OH species and occasional association between ENH3 and EBARRIER, Ni1V2O6 (Ni1) was rationally chosen as a platform to isolate mono-dentate SO32-/SO42- species for use as BA--H+ bonds via protonation to increase collision frequency (k’APP,0) alongside with disclosure of advantages of SO32-/SO42--functionalized Ni1V2O6 (Ni1-S) over Ni1 in reducing wet NOX. Ni1-S outperformed Ni1 in achieving a larger BA--H+ quantity (k’APP,0↑), increasing H2O tolerance, and elevating oxygen mobility, thus promoting NOX reduction activity/consequences under SO2-excluding gases. V2O5-WO3 composite simulating a commercial catalyst could isolate mono-dentate SO32-/SO42- species and served as a control (V2O5-WO3-S) for comparison. Ni1-S was superior to V2O5-WO3-S in evading ammonium (bi-)sulfate (AS/ABS) poison accumulation and expediting AS/ABS pyrolysis efficiency, thereby improving AS/ABS resistance under SO2-including gases, while enhancing resistance against hydro-thermal aging.