Materials Design SARL, 42 avenue Verdier, 92120 Montrouge, France.
TOTAL SE, Total Exploration Production, Liquefied Natural Gas - Acid Gas Entity, CCUS R&D Program, 2 Place Jean Milier, 92078 Paris, France.
J Chem Inf Model. 2021 Apr 26;61(4):1814-1824. doi: 10.1021/acs.jcim.0c01386. Epub 2021 Mar 12.
Aqueous tertiary amine solutions are increasingly used in industrial CO capture operations because they are more energy-efficient than primary or secondary amines and demonstrate higher CO absorption capacity. Yet, tertiary amine solutions have a significant drawback in that they tend to have lower CO absorption rates. To identify tertiary amines that absorb CO faster, it would be efficacious to have a quantitative and predictive model of the rate-controlling processes. Despite numerous attempts to date, this goal has been elusive. The present computational approach achieves this goal by focusing on the reaction of CO with OH forming HCO. The performance of the resulting model is demonstrated for a consistent experimental data set of the absorption rates of CO for 24 different aqueous tertiary amine solvents. The key to the new model's success is the manner in which the free energy barrier for the reaction of CO with OH is evaluated from the differences among the solvation free energies of CO, OH, and HCO, while the p of the amines controls the concentration of OH. These solvation energies are obtained from molecular dynamics simulations. The experimental value of the free energy of reaction of CO with pure water is combined with information about measured rates of absorption of CO in an aqueous amine solvent in order to calibrate the absorption rate model. This model achieves a relative accuracy better than 0.1 kJ mol for the free energies of activation for CO absorption in aqueous amine solutions and 0.07 g L min for the absorption rate of CO. Such high accuracies are necessary to predict the correct experimental ranking of CO absorption rates, thus providing a quantitative approach of practical interest.
水基叔胺溶液由于比伯胺和仲胺更节能，且具有更高的 CO 吸收能力，因此越来越多地用于工业 CO 捕集操作中。然而，叔胺溶液有一个显著的缺点，即它们的 CO 吸收速率往往较低。为了找到吸收 CO 更快的叔胺，建立一个定量且可预测的速率控制过程模型将是有效的。尽管迄今为止已经进行了多次尝试，但这一目标仍难以实现。本计算方法通过关注 CO 与 OH 反应形成 HCO 的过程来实现这一目标。该模型的性能通过对 24 种不同水基叔胺溶剂中 CO 吸收速率的一致实验数据集进行了验证。新模型成功的关键在于通过 CO、OH 和 HCO 的溶剂化自由能差异来评估 CO 与 OH 反应的自由能势垒，而胺的 p 值则控制 OH 的浓度。这些溶剂化能是通过分子动力学模拟获得的。将 CO 与纯水反应的自由能实验值与 CO 在水胺溶剂中吸收速率的测量值结合起来，以校准吸收速率模型。该模型对 CO 在水胺溶液中吸收的活化自由能的相对精度优于 0.1 kJ/mol，对 CO 吸收速率的相对精度优于 0.07 g/L·min。这样的高精度是预测正确的 CO 吸收速率实验排序所必需的，从而提供了一种具有实际意义的定量方法。
