Fan Xing, Li Jian, Qiu Danqi, Zhu Tianle
Key Laboratory of Beijing on Regional Air Pollution Control, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, China.
Key Laboratory of Beijing on Regional Air Pollution Control, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, China.
J Environ Sci (China). 2018 Apr;66:94-103. doi: 10.1016/j.jes.2017.05.033. Epub 2017 May 27.
Effects of carrier gas composition (N/air) on NH production, energy efficiency regarding NH production and byproducts formation from plasma-catalytic decomposition of urea were systematically investigated using an AlO-packed dielectric barrier discharge (DBD) reactor at room temperature. Results show that the presence of O in the carrier gas accelerates the conversion of urea but leads to less generation of NH. The final yield of NH in the gas phase decreased from 70.5%, 78.7%, 66.6% and 67.2% to 54.1%, 51.7%, 49.6% and 53.4% for applied voltages of 17, 19, 21 and 23kV, respectively when air was used as the carrier gas instead of N. From the viewpoint of energy savings, however, air carrier gas is better than N due to reduced energy consumption and increased energy efficiency for decomposition of a fixed amount of urea. Carrier gas composition has little influence on the major decomposition pathways of urea under the synergetic effects of plasma and AlO catalyst to give NH and CO as the main products. Compared to a small amount of NO formed with N as the carrier gas, however, more byproducts including NO and NO in the gas phase and NHNO in solid deposits were produced with air as the carrier gas, probably due to the unproductive consumption of NH, the possible intermediate HNCO and even urea by the abundant active oxygen species and nitrogen oxides generated in air-DBD plasma.
在室温下，使用填充有AlO的介质阻挡放电（DBD）反应器，系统地研究了载气组成（N/空气）对尿素等离子体催化分解过程中NH生成、NH生成的能量效率以及副产物形成的影响。结果表明，载气中O的存在加速了尿素的转化，但导致NH的生成量减少。当使用空气作为载气而非N时，对于17、19、21和23kV的施加电压，气相中NH的最终产率分别从70.5%、78.7%、66.6%和67.2%降至54.1%、51.7%、49.6%和53.4%。然而，从节能的角度来看，空气载气优于N，因为分解固定量的尿素时能耗降低且能量效率提高。在等离子体和AlO催化剂的协同作用下，载气组成对尿素的主要分解途径影响不大，主要产物为NH和CO。然而，与以N作为载气时形成少量NO相比，以空气作为载气时会产生更多的副产物，包括气相中的NO和NO以及固体沉积物中的NHNO，这可能是由于空气中DBD等离子体产生的大量活性氧物种和氮氧化物对NH、可能的中间产物HNCO甚至尿素的无效消耗所致。
