New insights into the deactivation mechanism of V2O5-WO3/TiO2 catalyst during selective catalytic reduction of NO with NH3: synergies between arsenic and potassium species

Lin Li; Lin Chen; Ming Kong; Qingcai Liu; Shan Ren

doi:10.1039/c9ra07545c

New insights into the deactivation mechanism of V₂O₅-WO₃/TiO₂ catalyst during selective catalytic reduction of NO with NH₃: synergies between arsenic and potassium species

RSC Adv. 2019 Nov 19;9(65):37724-37732. doi: 10.1039/c9ra07545c.

Authors

Lin Li^{1

2}, Lin Chen^{1

2}, Ming Kong^{1

2}, Qingcai Liu^{1

2}, Shan Ren^{1

2}

Affiliations

¹ Engineering Research Center for Energy and Environment of Chongqing, College of Materials Science and Engineering, Chongqing University Chongqing 400044 China ming.kong@cqu.edu.cn.
² Chongqing Key Laboratory of Vanadium-Titanium Metallurgy and New Materials, Chongqing University Chongqing 400044 PR China.

Abstract

Synergies between arsenic (As) and potassium (K) species in the deactivation of V₂O₅-WO₃/TiO₂ catalyst were investigated. Both arsenic oxide and potassium species presented a serious poisoning impact on catalyst activities, and the extent of poisoning of (As + K) was much stronger than their single superposition. The intrinsic reasons were explored and analyzed by N₂ physisorption, XPS, H₂-TPR, NH₃-TPD, NH₃-DRIFTS and in situ FTIR. Results indicated that BET surface area decreased due to the formation of a dense arsenic coating on the catalyst surface. V-OH active sites were destroyed by arsenic and As-OH acid sites were newly generated. After potassium species were added to arsenic-poisoned catalyst, K⁺ further neutralized the As-OH acid sites, and the amount and stability of both Lewis and BrØnsted acid sites decreased more greatly. Potassium also reacted with intermediate NH₂ ^- when the temperature was elevated to higher than 250 °C, which resulted in more NH₃ consumption and NH₃-SCR reaction inhibition. The extent of deactivation was related to the potassium species when both poisons reacted on the catalyst, and the influence sequence followed AsKS < AsKN < AsKC. As₂O₃ + K₂SO₄ presented the weakest impact among these three poisoned catalysts due to the resistance of SO₄ ^2- to arsenic.