Optimization of nitrogen-doped sludge char preparation and mechanism study for catalytic oxidation of NO at room temperature  

作　　者：Wenyi Deng Yongkang Zhang Mingtao Hu Ruoting Wang Yaxin Su 

机构地区：[1]College of Environmental Science and Engineering,Donghua University,Shanghai 201620,China

出　　处：《Journal of Environmental Sciences》2025年第4期503-514,共12页环境科学学报(英文版)

基　　金：supported by Shanghai Pujiang Program(No.22PJD001);the Fundamental Research Funds for the Central Universities(No.2232021G-11).

摘　　要：Catalytic oxidation of NO at room temperature was carried out over nitrogen(N)-doped sludge char(SC)prepared from pyrolysis ofmunicipal sewage sludge,and urea was adopted as nitrogen source.The effects of different N-doping methods(one-step and two-step method),dried sludge(DS)/urea mass ratios(5:1,4:1,3:1,2:1,and 1:1),SC preparation procedures(pyrolysis only,pyrolysis with acid washing,and pyrolysis with KOH activation and acid washing),and different pyrolysis temperatures(500,600,700,and 800°C)on the catalytic oxidation of NO were compared to optimize the procedure for SC preparation.The results indicated that N-doping could obviously promote the catalytic performance of SC.The one-step method with simultaneous sludge pyrolysis(at 700°C),KOH activation,and N-doping(DS/urea of 3:1)was the optimal procedure for preparing the N-doped SC with the NO conversion rate of 54.7%,whereas the optimal NO conversion rate of SC without N-doping was only 47.3%.Urea worked both as carbon and nitrogen source,which could increase about 2.9%-16.5%of carbon and 24.8%-42.7%of nitrogen content in SC pyrolyzed at 700°C.N-doping significantly promoted microporosity of SC.The optimal N-doped SC showed specific surface areas of 571.38 m^(2)/g,much higher than 374.34 m^(2)/g of the optimal SC without N-doping.In addition,N-doping also increased amorphousness and surface basicity of SC through the formation of N-containing groups.Finally,three reaction paths,i.e.microporous reactor,active sites,and basic site control path,were proposed to explain the mechanism of N-doping on promoting the catalytic performance of NO.

关 键 词：Sewage sludge NO oxidation Pyrolysis UREA CHAR Nitrogen doping 

分 类 号：X51[环境科学与工程—环境工程] TQ426[化学工程]