Conference abstract – GHGT-17: “CESAR1 solvent degradation in pilot and laboratory scale”

The non-proprietary CESAR1 amine blend has been widely studied for use as a solvent for post-combustion CO2 capture. 1–5 Despite of its relative popularity in the solvent market, there are still many knowledge gaps connected to the stability of CESAR1. The mixture of 2-amino-2-methyl propanol (AMP, CAS 124-68-5) and piperazine (PZ, CAS 110-85-0) is known to be much more stable than ethanolamine (MEA, CAS 141-43-5), both under oxidising conditions, thermal stress, and at the cyclic conditions in the CO2 capture plant. Despite of solvent degradation being low compared to other solvents, degradation phenomena need to be fully understood before a solvent can be safely implemented for large or full-scale CO2 capture from industrial sources, to fully comprehend potential environmental and operational impacts, and ensure safety for operators and neighbours.

In this work, we aim to fully elucidate the degradation patterns of CESAR1 at industry relevant conditions. Oxidative and thermal degradation experiments with AMP, PZ, and CESAR1 will be performed, and their degradation patterns and chemistry will be compared to solvent samples from industrial operations. In the Norwegian CCS research centre (NCCS) and the HEU project AURORA, new CESAR1 degradation compounds have been identified and quantified. Currently, LC-MSMS methods for the quantification of more than 30 CESAR1 specific degradation compounds are available at SINTEF, in addition to generic amine degradation compounds such as carboxylates, aldehydes, and alkylamines. A total nitrogen (TN) analysis was also performed to assess whether all nitrogen containing degradation compounds have been identified in the used solvent.

A CESAR1 solvent sample from a pilot scale operation at the Technology Centre Mongstad (TCM) is currently partly characterised. Figure 1 shows the concentrations of 29 of the components present in the used solvent. In addition to these, acetone (148 mg/L), formaldehyde (89 mg/L), and acetaldehyde (4 mg/L), as well as the solvent amines AMP (264 g/kg) and PZ (94 g/kg) were also quantified. Furthermore, 20 other compounds were also included in the analysis of the sample, but none of them were found above their respective limits of quantification (0.1-1 mg/kg, depending on compound).