Co-or Ni-modified Sn-MnOx low-dimensional multi-oxides for high-efficient NH3-SCR De-NOx:Performance optimization and reaction mechanism

• 作者: Fengyu Gao Chen Yang Xiaolong Tang Honghong Yi Chengzhi Wang
• 来源期刊: 环境科学学报（英文版）
• 年，卷（期）: 2022,（3）
• 页码范围: 204-218
• 页数: 15页
• 语种: 英文

摘要

NH3-SCR performances were explored to the relationship between structure morphology and physio-chemical properties over low-dimensional ternary Mn-based catalysts prepared by one-step synthesis method.Due to its strong oxidation performance,Sn-MnOx was prone to side reactions between NO,NH3 and O2,resulting in the generation of more NO2 and N2O,here most of N2O was driven from the non-selective oxidation of NH3,while a small part generated from the side reaction between NH3 and NO2.Co or Ni doping into Sn-MnOx as solid solution components obviously stronged the electronic interaction for actively mobi-lization and weakened the oxidation performance for signally reducing the selective ten-dency of side reactions to N2O.The optimal modification resulted in improving the surface area and enhancing the strong interaction between polyvalent cations in Co/Ni-Mn-SnO2 to provide more surface adsorbed oxygen,active sites of Mn3+ and Mn4+,high-content Sn4+and plentiful Lewis-acidity for more active intermediates,which significantly broadened the activity window of Sn-MnOx,improved the N2 selectivity by inhibiting N2O formation,and also contributed to an acceptable resistances to water and sulfur.At low reaction tem-peratures,the SCR reactions over three catalysts mainly obeyed the typical Elye-rideal (E-R)routs via the reactions of adsorbed L-NHx (x =3,2,1) and B-NH4+ with the gaseous NO to generate N2 but also N2O by-products.Except for the above basic E-R reactions,as increas-ing the reaction temperature,the main adsorbed NOx-species were bidentate nitrates that were also active in the Langmuir-Hinshelwood reactions with adsorbed L-NHx species over Co/Ni modified Mn-SnO2 catalyst.