Wen Zhenjing, Huang Bangfu, Shi Zhe, Yang Zhengyu, Dai Meng, Li Wanjun, Zi Gaoyong, Luo Liubin
Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology Kunming 650093 China
Key Laboratory of Clean Metallurgy of Complex Iron Resources, Yunnan University Kunming 650093 China.
RSC Adv. 2022 May 19;12(24):14964-14975. doi: 10.1039/d2ra02006h. eCollection 2022 May 17.
In the process of industrial flue gas denitration, the presence of heavy metals, especially Zn salts, is known to lead to the deactivation of the denitration catalysts. However, the specific mechanism of the catalyst deactivation remains unclear. In this paper, the mechanism of the ZnCl- and ZnSO-induced deactivation of low-temperature denitration catalysts in the carbon oxide (CO) selective catalytic reduction (CO-SCR) reaction was investigated using a Cu/activated carbon (AC) catalyst, in which HNO/AC was used as the carrier. Cu/AC, ZnCl-Cu/AC, and ZnSO-Cu/AC catalysts were prepared by the incipient wetness impregnation method. The physicochemical properties of the catalyst were examined the Brunauer-Emmett-Teller method, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy analyses, which proved the mechanism of catalyst denitrification and enabled the elucidation of the toxicity mechanism of the Zn salts on the Cu/AC catalyst for CO-SCR denitration at low temperatures. The results show that Zn doping reduces the physical adsorption of CO and NO and decreases the concentration of Cu and chemisorbed oxygen (O), leading to the reduction of active sites and oxygen vacancies, thus inhibiting the denitration reaction. Moreover, ZnCl is more toxic than ZnSO because Cl not only occupies oxygen vacancies but also inhibits O migration. In contrast, SO increases the surface acidity and promotes O supplementation. This study can provide a reference for the development of CO-SCR denitration catalysts with high resistance to Zn salt poisoning.
在工业烟气脱硝过程中，已知重金属尤其是锌盐的存在会导致脱硝催化剂失活。然而，催化剂失活的具体机制仍不清楚。本文以HNO/AC为载体，采用Cu/活性炭（AC）催化剂，研究了ZnCl和ZnSO对低温脱硝催化剂在一氧化碳（CO）选择性催化还原（CO-SCR）反应中失活的机制。采用初湿浸渍法制备了Cu/AC、ZnCl-Cu/AC和ZnSO-Cu/AC催化剂。通过Brunauer-Emmett-Teller法、X射线衍射、X射线光电子能谱和傅里叶变换红外光谱分析对催化剂的物理化学性质进行了研究，证实了催化剂脱硝的机制，并阐明了锌盐对Cu/AC催化剂低温CO-SCR脱硝的毒性机制。结果表明，Zn掺杂降低了CO和NO的物理吸附，降低了Cu和化学吸附氧（O）的浓度，导致活性位点和氧空位减少，从而抑制了脱硝反应。此外，ZnCl比ZnSO毒性更大，因为Cl不仅占据氧空位，还抑制O的迁移。相比之下，SO增加了表面酸度并促进了O的补充。该研究可为开发高抗锌盐中毒的CO-SCR脱硝催化剂提供参考。
