Low temperature plasma-catalytic NOx synthesis in a packed DBD reactor: Effect of support materials and supported active metal oxides
Low temperature plasma-catalytic NOx synthesis in a packed DBD reactor: Effect of support materials and supported active metal oxides
复制标题
DOI：
10.1016/j.apcatb.2016.04.055
复制
发表时间：
2016-10-05
影响因子：
22.1
通讯作者：
Wang, Q.
中科院分区：
文献类型：
--
作者：
Patil, B. S.;Cherkasov, N.;Wang, Q.
介绍了常压低温等离子体催化N-2和O-2直接合成NOx的方法，该方法被认为是替代Haber-Bosch工艺的一种有吸引力的选择。本研究通过在介质阻挡放电(DBD)反应器中填充不同的催化剂载体材料，对直接合成NOx进行了研究。载体材料及其颗粒大小对NOx浓度均有显著影响。这归因于不同的表面积、相对介电常数和颗粒形状。采用非热等离子体-催化DBD反应器可以在较低的温度下实现氮气的固定，可作为低温合成的替代技术。最小颗粒尺寸为250-160微米的γ-Al_2O_3的NOx浓度最高，比能耗最低。在S停留时间为0.4时，NOx浓度达到5700ppm，N-2/O-2进料比为1是产生NOx的最佳条件。为了强化等离子体中NOx的生成，在填充式DBD反应器中对一系列以γ-Al_2O_3为载体的金属氧化物催化剂进行了测试。与γ-Al_2O_3相比，5%的WO_3/-γ-Al_2O_3催化剂使NOx浓度进一步提高了约10%，而Co3O_4和PbO等氧化催化剂的NOx浓度略有提高(接近5%)。这些数据表明，在所研究的条件下，氧活化在等离子体催化固氮中起着次要的作用，而主要作用归因于大比表面积等离子体催化剂锐边上微放电的产生。然而，当活性金属氧化物的负载量增加到10%时，NO的选择性降低，这表明NO可能通过与表面氧物种的反应热氧化为NO2。(C)2016爱思唯尔B.V.保留所有权利。
The direct synthesis of NOx from N-2 and O-2 by non-thermal plasma at an atmospheric pressure and low temperature is presented, which is considered to be an attractive option for replacement of the Haber-Bosch process. In this study, the direct synthesis of NOx was studied by packing different catalyst support materials in a dielectric barrier discharge (DBD) reactor. The support materials and their particle sizes both had a significant effect on the concentration of NOx. This is attributed to different surface areas, relative dielectric constants and particles shapes. The nitrogen could be fixed at substantially lowered temperatures by employing non-thermal plasma-catalytic DBD reactor, which can be used as an alternative technology for low temperature synthesis. The gamma-Al2O3 with smallest particles size of 250-160 mu m, gave the highest concentration of NOx and the lowest specific energy consumption of all the tested materials and particle sizes. The NOx concentration of 5700 ppm was reached at the highest residence time of 0.4 s and an N-2/O-2 feed ratio of 1 was found to be the most optimum for NOx production. In order to intensify the NOx production in plasma, a series of metal oxide catalysts supported on gamma-Al2O3 were tested in a packed DBD reactor. A 5% WO3/-gamma-Al2O3 catalyst increased the NOx concentration further by about 10% compared to gamma-Al2O3, while oxidation catalysts such as Co3O4 and PbO provided a minor (similar to 5%) improvement. These data suggest that oxygen activation plays a minor role in plasma catalytic nitrogen fixation under the studied conditions with the main role ascribed to the generation of microdischarges on sharp edges of large-surface area plasma catalysts. However, when the loading of active metal oxides was increased to 10%, NO selectivity decreased, suggesting possibility of thermal oxidation of NO to NO2 through reaction with surface oxygen species. (C) 2016 Elsevier B.V. All rights reserved.