Study On The Microwave Catalytic Denitration Performance Of Lanthanum Nickelate-based Perovskite-Type Oxide

Nitrogen oxides are the main atmospheric pollutants that pose serious risk to the ecosystem and human health.How to effectively remove nitrogen oxides from waste gas is a non-trivial problem in the air pollution control process.Although selective catalytic reduction（SCR）is currently the most mature NO_x treatment technology,it has the disadvantages of a requirement for a reducing agent and susceptibility to side reactions.In contrast,the direct decomposition of NO with a simple process and no need to add additional reducing agents has become an important research direction for the removal of nitrogen oxides.This process can be realized by lowering the reaction activation barrier（364 k J/mol）on a suitable catalyst,while the decomposition products are the harmless nitrogen and oxygen molecules.Perovskite oxides are very suitable for direct NO decomposition owing to their low cost,high thermal stability,and reasonable catalytic activity.However,the direct decomposition of NO on perovskite oxides under conventional heating conditions still suffers from the problems of high reaction temperature and severe oxygen inhibition.Microwave irradiation can accelerate the rate of catalytic reaction and has the characteristics of selective heating,which provides a new way to solve the problems of NO decomposition on perovskite oxides.Therefore,microwave irradiation was combined with perovskite oxide catalyst to decompose no directly.La Ni O₃ based catalysts substituted at different A sites and B sites were loaded on microwave absorbing and heating supports,and then the direct decomposition of no was carried out under the condition of microwave irradiation.The effects of reaction temperature,oxygen concentration and gas flow rate on the catalytic activity of the above catalysts were investigated under microwave irradiation.In this paper,microwave and NO decomposition reaction were combined to study the direct catalytic decomposition of NO by La Ni O₃-based perovskite under microwave irradiation.Under microwave irradiation,the activity of La Ni O₃-based perovskite oxide catalyst supported on microwave-absorbing heating ceramic support prepared by sol-gel method for NO direct decomposition was tested.The process parameters investigated included reaction temperature,oxygen concentration,gas flow rate,etc.Under microwave irradiation,each catalyst has the highest NO conversion when the reaction temperature was 400℃.The highest NO conversion of A-substituted La_0.8K_0.2Ni O₃ and La_0.7K_0.3Ni O₃ catalysts were 98.9%and 98.2%respectively,which were 3.6%and 2.9%higher than that of the La Ni O₃ catalyst.The highest NO conversion of B-substituted La Co O₃ and La Ni_0.9Co_0.1O₃ catalysts were 98.8%and 96.6%respectively,which were 3.5%and 1.3%higher than that of the La Ni O₃ catalyst.The highest NO conversion of the La_0.7K_0.3Ni_0.9Co_0.1O₃ catalyst was 98.3%,which was 0.1%higher than that of the La_0.7K_0.3Ni O₃ catalyst.Due to the microwave selective effect,La Ni O₃-based catalysts showed good anti-oxygen inhibition under oxygen-enriched conditions,and the selectivity of N₂ was more than 99%.