Unraveling the anti-poisoning mechanism of highly dispersed Ni atoms enhanced porous MnO_x catalysts in the selective reduction of NO_x by NH₃.

The development of efficient catalysts for the purification of flue gases at low temperatures remains a significant challenge. In particular, the selective catalytic reduction (SCR) of nitrogen oxides (NOx) is a crucial process that requires highly effective and stable catalysts. To address this issue, researchers have designed a novel catalyst, Ni0.1Mn0.9Ox, which consists of highly dispersed Ni atoms doped into a manganese oxide (MnOx) framework. This catalyst has shown promising results in terms of its long-term stability, with a retention of up to 80% of its initial activity after 18 hours of operation under harsh conditions, including the presence of sulfur dioxide (SO2) and water (H2O). The exceptional performance of the Ni0.1Mn0.9Ox catalyst can be attributed to several factors. The introduction of Ni atoms into the MnOx framework enhances the redox properties and surface acidity of the catalyst, which in turn modulates the electronic structure of the active Mn sites. This leads to improved catalytic activity and stability. Furthermore, the anti-poisoning mechanism of the catalyst involves the weakening of electron transfer between the Mn site and SO2, which inhibits the adsorption of SO2 and reduces the deactivation of the catalyst. Additionally, the presence of H2O on the Ni sites can actually facilitate the adsorption of ammonia (NH3) by replenishing depleted Brønsted acid sites. However, excessive H2O can have a negative impact on the catalyst's performance. The mesoporous structure of the catalyst also plays a crucial role in enhancing the mass transfer rate and reducing the accumulation of harmful substances. Overall, this study provides valuable insights into the design of SCR catalysts with excellent anti-poisoning ability, which can be applied to the development of more efficient and sustainable flue gas purification technologies. Link: https://pubmed.ncbi.nlm.nih.gov/40288278/