Department of Civil, Structural, and Environmental Engineering, State University of New York at Buffalo , Buffalo, New York 14260, United States.
Environ Sci Technol. 2016 May 17;50(10):5189-96. doi: 10.1021/acs.est.5b05443. Epub 2016 Apr 25.
NO oxidation catalyzed by porous materials is difficult to implement under industrial conditions because moisture in combustion exhaust streams blocks oxidation sites, decreasing NO conversion. In this work, hydrophobic cross-linked polymers are tested as NO oxidation catalysts to overcome these negative impacts associated with moisture. Although activated carbons (ACs) outperform hyper-cross-linked polymers by >88% and low-cross-linked polymers by >463% under dry conditions, their NO conversion drops to 0% when 50% relative humidity is added. Performance of hyper-cross-linked and low-cross-linked polymers, however, decreases by only 19-35% and <6%, respectively, for NO conversion in the presence of moisture. NO conversion differences between materials are attributed to differences in the catalysts' initial hydrophilicity and their proclivity to react with generated NO2, which also increases hydrophilicity. While the initial hydrophobicity of the polymers contributes to their consistent performance, it is their intrinsic ability to resist NO2 reduction reactions, compared to AC, that makes them the more viable catalyst for industrial application. Results suggest that the polymer hyper-cross-linking process improves steady-state NO conversion but increases NO2 surface reactivity and hydrophilicity.
由于燃烧废气中的水分会堵塞氧化位，降低 NO 转化率，因此，在工业条件下，很难实现多孔材料催化的 NO 氧化。在这项工作中，疏水性交联聚合物被测试为 NO 氧化催化剂，以克服与水分相关的这些负面影响。尽管在干燥条件下，活性炭 (AC) 的 NO 转化率比超交联聚合物高>88%，比低交联聚合物高>463%，但当加入 50%相对湿度时，其 NO 转化率降至 0%。然而，在存在水分的情况下，超交联和低交联聚合物的性能仅分别下降了 19-35%和<6%。材料之间的 NO 转化率差异归因于催化剂初始亲水性的差异以及它们与生成的 NO2 反应的倾向，这也会增加亲水性。虽然聚合物的初始疏水性有助于其性能的一致性，但与 AC 相比，其内在的抵抗 NO2 还原反应的能力，使它们成为更可行的工业应用催化剂。结果表明，聚合物的超交联过程提高了 NO 的稳态转化率，但增加了 NO2 的表面反应性和亲水性。
