Absorption of carbon dioxide in mixture of N-Methyl-2-Pyrrolidone and six different chemical solvents

Abstract

Today, the emission of carbon dioxide (CO2) has increased sharply as a result of world industrialization and an increase in energy demand. Therefore, finding an economic way to reduce CO2 emissions has been considered a crucial subject for industries. In this research, the mixture of n-methyl-2-pyrrolidone (NMP) and six various chemical solvents of monoethanolamine (MEA), methyldiethanolamine (MDEA), potassium carbonate (K2CO3), potassium glycinate (KGly), potassium argininate (KArg), and triethylenetetramine (TETA) is applied in a semi-continuous bubble column reactor system at pressure 1 bar and room temperature. Based on the result, the addition of the NMP to water causes the absorption capacity to increase. But, it has a negative effect on the absorption capacity of chemical absorbents so that the order of absorption is aqueous solvent (water 95 wt% + chemical compound 5 wt%) > semi-aqueous solvent (water 45 wt% + NMP 50 wt% + chemical compound 5 wt%) > non-aqueous solvent (NMP 95 wt% + chemical compound 5 wt%), respectively. TETA with 637 and 538% absorption enhancement among aqueous and semi-aqueous solvents, respectively, and MEA with 572% absorption increment compared to water among non-aqueous solvents have shown the best absorption capacity. Also, KArg has the highest CO2 loading (mole CO2/mole chemical), therefore, KArg is a promising solvent to use in CO2 absorption. Further, due to the inability of the bubble column to tolerate high pressures, the effect of pressure (2, 5, 10 and 30 bar) on MDEA solutions has been investigated in a high-pressure batch system at temperature 298 K. It has been observed that an increase in pressure strongly affects the performance of non-aqueous solvents. So, the non-aqueous solvents are more effective when the partial pressure of CO2 is high.