The reaction between CO2 and aqueous amines to produce a charged carbamate product plays a crucial role in post-combustion capture chemistry when primary and secondary amines are used. In this paper, we report the low energy negative-ion CID results for several anionic carbamates derived from primary and secondary amines commonly used as post-combustion capture solvents. The study was performed using the modern equivalent of a triple quadrupole instrument equipped with a T-wave collision cell. Deuterium labeling of 2-aminoethanol (1,1,2,2,-d4-2-aminoethanol) and computations at the M06-2X/6-311++G(d,p) level were used to confirm the identity of the fragmentation products for 2-hydroxyethylcarbamate (derived from 2-aminoethanol), in particular the ions CN−, NCO− and facile neutral losses of CO2 and water; there is precedent for the latter in condensed phase isocyanate chemistry. The fragmentations of 2-hydroxyethylcarbamate were generalized for carbamate anions derived from other capture amines, including ethylenediamine, diethanolamine, and piperazine. We also report unequivocal evidence for the existence of carbamate anions derived from sterically hindered amines (Tris(2-hydroxymethyl)aminomethane and 2-methyl-2-aminopropanol). For the suite of carbamates investigated, diagnostic losses include the decarboxylation product (−CO2, 44 mass units), loss of 46 mass units and the fragments NCO− (m/z 42) and CN− (m/z 26). We also report low energy CID results for the dicarbamate dianion (−O2CNHC2H4NHCO2−) commonly encountered in CO2 capture solution utilizing ethylenediamine. Finally, we demonstrate a promising ion chromatography-MS based procedure for the separation and quantitation of aqueous anionic carbamates, which is based on the reported CID findings. The availability of accurate quantitation methods for ionic CO2 capture products could lead to dynamic operational tuning of CO2 capture-plants and, thus, cost-savings via real-time manipulation of solvent regeneration energies.
CO2与
水合胺反应生成带电的
碳酸酯产品,在使用一胺和二胺时在后燃烧捕获
化学中发挥着至关重要的作用。本文报告了一些常用于后燃烧捕获溶剂的一胺和二胺衍生的阴离子
碳酸酯的低能负离子碰撞解离(CID)结果。该研究采用现代三重四极杆仪器及T波碰撞池进行。对2-
氨基
乙醇(1,1,2,2,-d4-2-
氨基
乙醇)的重氮标记以及M06-2X/6-311++G(d,p)
水平的计算用于确认2-羟基乙基
碳酸酯(源自2-
氨基
乙醇)裂解产物的身份,特别是离子CN−、NCO−及易于失去的 和
水;后者在凝聚态
异氰酸酯化学中已有先例。2-羟基乙基
碳酸酯的裂解情况为来自其他捕获胺(包括
乙二胺、
二乙醇胺和
哌嗪)的
碳酸酯阴离子进行了概括。我们还报告了来源于空间位阻较大的胺(
Tris(2-羟基甲基)
氨基
甲烷和2-甲基-2-
氨基
丙醇)的
碳酸酯阴离子存在的明确证据。对于所研究的一系列
碳酸酯,特征性失去包括脱羧产物(− , 44质量单位)、损失46质量单位,以及片段NCO−(m/z 42)和CN−(m/z 26)。我们还报告了在利用
乙二胺的 捕获溶液中常遇到的二
碳酸酯二阴离子(−O2CNHC2H4NH −)的低能CID结果。最后,我们展示了一种基于离子色谱-MS的有前景的
水合阴离子
碳酸酯分离和定量程序,该程序基于所报告的CID发现。对于离子 捕获产物的准确定量方法的可用性可能导致 捕获工厂的动态操作调整,从而通过实时操控溶剂再生能量实现成本节约。