Potassium Phenolate as An Alternative to Amine-Based Capture Agents for CO2 Capture
James E. Wheatley, et al. International Journal of Greenhouse Gas Control, 2019, 88,353-360.
Amine mixtures are the primary absorbers for CO2 capture, but they suffer from issues such as high energy requirements and toxicity. Potassium phenolate was reported as a phenol-based capture reagent as an amine-free alternative in blends. Results showed that potassium phenoxide is indeed fully capable of acting as CO2 capture solvent component particularly when used in conjunction with amines capable of carbamate formation.
Preparation of capture solvents
· The following amine solutions were required: 5 M MEA; 1 M MEA/ 3 M N-methyldiethanolamine (MDEA); 1 M MEA/3 M 2-methyl-2-amino-1-propanol (AMP); 1 M PZ/3 M AMP. For each of these compositions, a 250 mL stock solution was prepared from the requisite amount of each amine, to which was added DSS (0.27 g, 1.25 mmol), the mixture dissolved in distilled water (18 MΩ) and diluted up to a volume of 250 mL.
· The following phenoxide solutions were required: 1 M KOPh; 1 M MEA/1 M KOPh; 1 M MEA/2 M KOPh; 2 M MEA/1 M KOPh; 1 M MEA/ 3 M KOPh; 2 M MEA/2 M KOPh. For each of these compositions, a 250 mL stock solution was prepared. Potassium hydroxide was dissolved in water (30 mL) and neutralised by an equimolar amount of phenol (9.9 wt% water) at 0 °C. This mixture was warmed up to room temperature, DSS (0.27 g, 1.25 mmol) and MEA added, and the whole was diluted up to 250 mL with distilled water.