Enhancements of monoethanolamine CO2 absorption rate and degradation in the presence of nickel nanoparticles catalysts

Abstract

In the study of the catalytic effect of nickel nanoparticles (NiNPs) on amine-based CO2 capture systems, monoethanolamine (MEA) was subjected to a CO2 loading at greatly varying concentrations (3–30 wt%) at two temperatures (20 °C and 50 °C) for the first time in a lab study to the best of our knowledge. This study shows that NiNPs can enhance the rate of CO2 absorption into MEA and that its enhancement is greater at 20 °C than at 50 °C. Solutions were loaded with CO2 until full saturation and the mass gain was recorded. At 20 °C the overall enhancement ranged between 4.0–7.4% with the optimum (>7.0%) observed at concentrations of 5 wt% and 20 wt% of MEA with NiNPs. In addition, there were large reductions in the time that it takes to fully saturate the MEA with CO2, (up to a 42% reduction) and there were differences in peak loading (molCO2/molmea) between the NiNPs solution and the control (without NiNPs) (of up to 12.5% for the same time at 20 °C and 30 wt% of MEA with NiNPs). For the first time to the best of our knowledge, the degradation of MEA with and without NiNPs was studied; an oxidative degradation experiment (30 wt%, 0.4 molCO2/molmea, 7.5 mL/min CO2, 0.35 L/min air, 55 °C) based on typical absorber conditions and a thermal degradation experiment based on typical stripper conditions (30 wt%, 0.5 molCO2/molmea, 135 °C) were carried out. Gas chromatography-mass spectrometry was used to identify and quantify the major degradation compounds. It is found that NiNPs increase the rate of both oxidative and thermal degradation.