CO2 capture from water-gas shift process plant: Comparative bench-scale pilot plant investigation of MDEA-PZ blend vs novel MDEA activated by 1,5-diamino-2-methylpentane

Abstract

This research is a bench-scale pilot plant investigation of novel amine solvent blend containing MDEA and 1,5-diamino-2-methylpentane (DA2MP) for CO2 capture from water-gas shift process plant (H2 production). The CO2 concentration used in this study (50 vol.% CO2 with N2 balance) is similar to that of the water-gas shift product gas. The CO2 capture performance of the MDEA-DA2MP blend was compared to the standard 3 kmol/m3 MDEA-0.5 kmol/m3 PZ blend (34.4 wt.% MDEA-5 wt.% PZ). The low concentration of PZ in this study is because of the chemical toxicity of PZ and possible precipitation at medium to high concentration. The MDEA concentration in the MDEA-DA2MP blend was kept constant at 3 kmol/m3 while the DA2MP was varied from 0.5 kmol/m3 (6.75 wt.%) to 1.5 kmol/m3 (20.3 wt.%). The pilot plant analysis was performed at a gas flow rate, amine solution flow rate, and reboiler temperature of 14 SLPM, 50 mL/min, and 120 C respectively. Pilot plant results revealed that the higher MDEA-DA2MP blend concentration possesses higher CO2 capture efficiency (up to 24%), higher CO2 absorption rate (up to 23.5%) and higher absorber mass transfer coefficient (up to 23.9%) compared to the MDEA-PZ blend. It was also discovered that the high MDEA-DA2MP concentration has lower regeneration energy (up to 25.4%), lower initial amine solution utilized (up to 20.5%), lower desorber mass transfer coefficient (up to 32.5%) compared to the MDEA-PZ blend. However, the optimal amine concentration is the 3 kmol/m3 MDEA-1 kmol/m3 DA2MP blend. Overall results show that the MDEA-DA2MP blend can offer a cost-effective and energy efficient CO2 capture compared to MDEA-PZ.