Development of an energy-efficient and cost-effective catalytic regeneration system in the post-combustion CO2 capture process (Flexible Funding 2021)

Eni Oko at the University of Hull was awarded funding in the UKCCSRC’s Flexible Funding 2021 Call to look at the “Development of an energy-efficient and cost-effective catalytic regeneration system in the post-combustion CO2 capture process”.

Current studies in the literature show that catalyst-assisted regeneration in the post-combustion CO2 capture process, illustrated in Fig 1, not only reduces the thermal energy requirement but also enables solvent regeneration at a lower temperature under 100oC, in contrast to over 120oC without catalyst-assisted regeneration. This project developed a computational model to screen and analyse different catalysts for catalyst-assisted regeneration in solvent-based post-combustion CO2 capture (PCC) process.

Figure 1: Schematic illustration of catalyst-assisted regeneration in the post-combustion CO2 capture system

A computational approach was adopted to screen different catalyst options to identify the potentially most energy-efficient in assisting the regeneration of CO2 loaded 30 wt% monoethanolamine solvent. The catalyst options evaluated included zeolite (HZSM-5), MoO3, Ce(SO4)2/ZrO2, V2O5 and Al2O3. The computational calculation was performed using Density Functional based Tight-Binding methods, an approximate DFT model in the ADF Suite (Computational Material Chemistry software). The results showed that HZSM-5 with an energy barrier of 0.009546 Hartree and activation energy of 29.84 kJ/mol has the highest potential to achieve reduced regeneration energy requirement (Figure 2).

Figure 2: Energy barrier for catalyst-assisted MEA-CO2 desorption

A process model of the PCC process with catalyst-assisted regeneration for 30 wt% MEA solvent and HZSM-5 catalyst was thereafter developed in Aspen Plus® with the solid phase catalytic reaction kinetics implemented as user-defined via FORTRAN subroutine. The integrated absorber-regenerator model was validated using pilot data from the Clean Energy Technologies Research Institute (CETRI), University of Regina, Canada with average deviations for rich loading and CO2 product mass flow rate within <10% for different conditions. The obtained thermal energy requirement was 6.5 GJ/ton CO2 but with a regeneration temperature below 100oC which confirms that the regeneration can be obtained using hot water rather than steam. The available data from CETRI is limited with several data unavailable for different operating parameters. It is therefore important to conduct extensive experiments to obtain a more robust validation.

This project, led by the University of Hull, UK was supported under the UK Carbon Capture and Storage Research Centre (UKCCSRC) Flexible Funding 2021 (Ref: EP/P026214/1).