非热等离子体强化TiO_(2)催化尿素分解副产物水解性能的研究  

Non-thermal plasma enhanced hydrolysis of urea decomposition by-products over TiO_(2)

作　　者：李泽严 樊星[1] 李坚[1] LI Zeyan;FAN Xing;LI Jian(Key Laboratory of Beijing on Regional Air Pollution Control,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]北京工业大学区域大气复合污染防治北京市重点实验室,北京100124

出　　处：《化工学报》2021年第9期4698-4707,共10页CIESC Journal

基　　金：国家自然科学基金项目(21707004,21547004);北京市自然科学基金项目(8152011)。

摘　　要：尿素-选择性催化还原技术低温下运行时尿素分解不彻底,易形成缩二脲、三聚氰酸和三聚氰胺等副产物。本研究将TiO_(2)催化剂与介质阻挡放电等离子体相结合,在程序升温条件下考察了载气中有无O_(2)时引入等离子体前后TiO_(2)催化尿素分解副产物水解的性能。结果表明:TiO_(2)表面缩二脲、三聚氰酸和三聚氰胺分别在43-261℃、217-300℃和199-300℃水解生成NH3和CO_(2),载气中有无O_(2)对催化水解过程几乎无影响。引入等离子体后缩二脲、三聚氰酸和三聚氰胺水解所需温度显著降低,载气中无O_(2)时引入等离子体NH3产率变化不大,副产物仅有少量N2O和NO,有O_(2)时NH3产率显著降低,且生成较多N2O、NO、NO_(2)及少量NH4NO_(2)和NH4NO_(3)。未来需从优化放电条件和催化剂组成等方面解决引入等离子体导致副产物形成等问题。When the urea-selective catalytic reduction technology runs at low temperatures,urea is not completely decomposed,and it is easy to form by-products such as biuret,cyanuric acid and melamine.In this study,TiO_(2) catalyst was combined with dielectric barrier discharge plasma for hydrolysis of urea decomposition by-products with or without O_(2) in the carrier gas under temperature-programmed conditions.Experimental results show that biuret,cyanuric acid and melamine over TiO_(2) could be hydrolyzed to NH3 and CO_(2) at 43-261℃,217-300℃and 199-300℃,respectively.The presence or absence of O_(2) in the carrier gas hardly affects the catalytic hydrolysis process.Introducing plasma significantly decreases the hydrolysis temperatures of biuret,cyanuric acid and melamine.Insignificant variation of NH3 yield and small amounts of N2O and NO by-products are observed when plasma is applied in the O_(2)-free carrier gas.In the O_(2)-containing case,NH3 yield obviously decreases while more N2O,NO,NO_(2) and small amounts of NH4NO_(2) and NH4NO_(3) are generated by applying plasma.To overcome drawbacks of the plasma-enhanced process,mainly the formation of by-products,further work is required in the future,such as optimizing discharge conditions and catalyst compositions.

关 键 词：尿素分解副产物 非热等离子体 催化 水解 选择性催化还原 

分 类 号：X511[环境科学与工程—环境工程]