Alkali metal-resistant mechanism for selective catalytic reduction of nitric oxide over V2O5/HWO catalysts

• Published in: Fuel (Guildford) 2021-11, Vol.304, p.121445, Article 121445
• Main Authors: Kang, Running, He, Junyao, Bin, Feng, Dou, Baojuan, Hao, Qinglan, Wei, Xiaolin, Nam Hui, Kwun, San Hui, Kwan
• Format: Article
• Language: English
• Subjects: Acidity; Alkali metal-resistant; Alkali metals; Ammonia; Bonding strength; Catalysts; Cellulose; Chemical reduction; Commercial bacterial cellulose; Morphology; Nitric oxide; Oxalic acid; Poisoning; Potassium; Precursors; SCR reaction; Selective catalytic reduction; Sulfur dioxide; V2O5/HWO catalyst; Vanadium pentoxide; X ray photoelectron spectroscopy
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2021.121445

[Display omitted] •The controllable morphology synthesis of hexagonal WO3 (HWO) was achieved by commercial bacterial cellulose (C).•The obtained V2O5/HWO-C catalyst exhibits effective resistance to K poisoning and SO2, and follows the Langmuir-Hinshelwood mechanism.•The detailed alkali metal-resistant pathways for the distribution of alkali metal ions (K+) on the K-V2O5/HWO-C catalyst were proposed. A series of V2O5/HWO catalysts are prepared by hydrothermal and impregnation methods using different precursors, among which the V2O5/HWO-C catalyst exhibited the optimal NH3-SCR performance. Compared to oxalic acid (O) and water (W), commercial bacterial cellulose (C) as a precursor can firstly achieve a more controllable synthesis to form hexagonal WO3 (HWO) of V2O5/HWO-C catalyst. Various characterization (XRD, N2-BET, TEM, SEM, XPS, EDX mapping, and NH3/NO-TPD-MS) indicate that a higher specific surface area, abundant active oxygen and surface acidity result from the V2O5/HWO-C catalyst. The reason is that HWO-C has an excellent and smooth rod-shaped morphology, which promotes high dispersion of V2O5 on its surface. In situ IR results show that the SCR follows the Langmuir-Hinshelwood (L-H) mechanism, where absorbed NOx intermediate species are formed on the V2O5 and react with the NH4+ and NH3abs groups of V2O5 and HWO. After loading 1.75 wt% K+, the obtained K-V2O5/HWO-C catalyst exhibits effective resistance to K poisoning and SO2, and retains 78 % NOx conversion efficiency at 360 °C after 10 h, attributed to the effective capture of K+ (1.04 wt%) in HWO-C channels via a new pathway, although approximately 0.71 wt% K+ are located on HWO-C external surface with weak bonding to V2O5.