Diamine based hybrid-slurry system for carbon capture

Hybrid adsorption-absorption slurry systems are very attractive for CO2 capture, given their ability to simultaneously lower regeneration energy and increase absorption rate and uptake, because of enhanced mass and heat transfer mechanisms. In this work, novel hybrid slurries were formulated from the dispersion of 1 wt.% of solid adsorbents in a water-lean solvent of 30 wt.% of Tetramethyl-1,3-diaminopropane (TMPDA) + 10 wt.% Ethanol (EtOH) for CO2 capture. Different solid particles were suspended in the water-lean solvent such as activated carbon, ion-exchanged zeolite Y (Mg-Y), and polyethyleneimine doped silicas (PEI-SG and PEI-MCM-41). The CO2 uptake of the solid and fluid components of the slurries was confirmed by pH, density, and Fourier transform infrared analysis. The neat water lean solvent reduced the absorption energy by 16 % and slightly increased the CO2 uptake by 0.6 % compared to the aqueous TMPDA solvent. Additionally, the hybrid slurries exhibited further reductions in absorption energy of 10 - 30 % compared to the benchmark TMPDA-based solvents. The PEI-MCM-41-based slurry presented the highest CO2 uptake of 0.33 g CO2.g-1 and lowest regeneration energy of 2261.30 kJ.kg-1 among the studied systems. Additionally, the hybrid slurry exhibited a 21 % reduction in CO2 uptake compared to the benchmark 30 wt.% aqueous monoethanolamine (MEA) and similar capacity to aqueous methyl diethanolamine (MDEA), however, resulting in a far higher reduction in absorption enthalpy of 56 %, and 29 % compared to aqueous MEA and MDEA, respectively. The results obtained here encourage further development and optimization of hybrid slurry systems as potential efficient systems for CO2 capture.