Department of Environmental Science & Engineering, Fudan University, 2005 Songhu Road, Shanghai 200438, China.
Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
Environ Sci Technol. 2021 Apr 20;55(8):5435-5441. doi: 10.1021/acs.est.0c08736. Epub 2021 Mar 16.
Although ceria-based catalysts serve as an appealing alternative to traditional VO-based catalysts for selective catalytic reduction (SCR) of NO with NH, the inevitable deactivation caused by SO at low temperatures severely hampers the ceria-based catalysts to efficiently control NO emissions from SO-containing stack gases. Here, we rationally design a strong sulfur-resistant ceria-based catalyst by tuning the electronic structures of ceria highly dispersed on acidic MoO surfaces. By using Ce L-edge X-ray absorption near edge structure spectra in conjunction with various surface and bulk structural characterizations, we report that the sulfur resistance of the catalysts is closely associated with the electronic states of ceria, particularly expressed by the Ce/Ce ratio related to the size of the ceria particles. As the Ce/Ce ratio increases up to or over 50%, corresponding to CeO/MoO( %, ≤ 2.1) with the particle size of approximately 4 nm or less, the non-bulk electronic states of ceria appear, where the catalysts start to show strong sulfur resistance. This work could provide a new strategy for designing sulfur-resistant ceria-based SCR catalysts for controlling NO emissions at low temperatures.
虽然基于铈的催化剂作为传统的基于 VO 的催化剂的替代品，用于选择性催化还原（SCR）NO 与 NH，但在低温下不可避免的 SO 导致的失活严重阻碍了基于铈的催化剂有效地控制含 SO 的废气中的 NO 排放。在这里，我们通过调整高度分散在酸性 MoO 表面上的 Ce 的电子结构，合理设计了一种具有强抗硫性的 Ce 基催化剂。通过使用 Ce L 边 X 射线吸收近边结构谱与各种表面和体结构表征相结合，我们报告说，催化剂的抗硫性与 Ce 的电子态密切相关，特别是与 CeO 颗粒尺寸相关的 Ce/Ce 比表达。当 Ce/Ce 比增加到或超过 50%时，对应于 CeO/MoO（%，≤2.1），CeO 颗粒尺寸约为 4nm 或更小，Ce 的非体电子态出现，此时催化剂开始表现出较强的抗硫性。这项工作为设计用于控制低温下 NO 排放的抗硫性 Ce 基 SCR 催化剂提供了一种新策略。
