Department of Chemical and Biological Engineering University at Buffalo, The State University of New York , Buffalo, New York 14260, United States.
Department of Civil and Environmental Engineering, Stanford University , Stanford, California 94305, United States.
Environ Sci Technol. 2017 Oct 17;51(20):11522-11536. doi: 10.1021/acs.est.7b02597. Epub 2017 Oct 6.
Amine-based absorption is the primary contender for postcombustion CO capture from fossil fuel-fired power plants. However, significant concerns have arisen regarding the formation and emission of toxic nitrosamine and nitramine byproducts from amine-based systems. This paper reviews the current knowledge regarding these byproducts in CO capture systems. In the absorber, flue gas NO drives nitrosamine and nitramine formation after its dissolution into the amine solvent. The reaction mechanisms are reviewed based on CO capture literature as well as biological and atmospheric chemistry studies. In the desorber, nitrosamines are formed under high temperatures by amines reacting with nitrite (a hydrolysis product of NO), but they can also thermally decompose following pseudo-first order kinetics. The effects of amine structure, primarily amine order, on nitrosamine formation and the corresponding mechanisms are discussed. Washwater units, although intended to control emissions from the absorber, can contribute to additional nitrosamine formation when accumulated amines react with residual NO. Nitramines are much less studied than nitrosamines in CO capture systems. Mitigation strategies based on the reaction mechanisms in each unit of the CO capture systems are reviewed. Lastly, we highlight research needs in clarifying reaction mechanisms, developing analytical methods for both liquid and gas phases, and integrating different units to quantitatively predict the accumulation and emission of nitrosamines and nitramines.
胺基吸收是从化石燃料发电厂进行燃烧后 CO 捕获的主要竞争者。然而,人们对胺基系统产生的有毒亚硝胺和硝胺副产物的形成和排放产生了重大关注。本文综述了 CO 捕集系统中这些副产物的现有知识。在吸收器中,烟道气 NO 溶解在胺溶剂中后会引发亚硝胺和硝胺的形成。根据 CO 捕集文献以及生物和大气化学研究,综述了反应机制。在解吸器中,胺与亚硝酸盐(NO 的水解产物)反应在高温下形成亚硝胺,但它们也可以按照准一级动力学热分解。讨论了胺结构(主要是胺顺序)对亚硝胺形成的影响及其相应的机制。尽管洗涤水装置旨在控制吸收器中的排放物,但当积累的胺与残留的 NO 反应时,它会导致额外的亚硝胺形成。与 CO 捕集系统中的亚硝胺相比,硝胺的研究要少得多。根据 CO 捕集系统各个单元的反应机制,综述了缓解策略。最后,我们强调了澄清反应机制、开发液相和气相分析方法以及整合不同单元以定量预测亚硝胺和硝胺积累和排放的研究需求。