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

[摘要] 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, N-2-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 degrees 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.

[发布日期] 2021-11-15

[关键词] Commercial bacterial cellulose;V2O5/HWO catalyst;Alkali metal-resistant;Poisoning;SCR reaction