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Co-adsorption of CO2 and H2O from ambient air

Co-adsorption of CO2 and H2O from ambient air


Recently, CO2 capture from air attracts more and more attentions. Because it is not only a pillar to deal with CO2 emissions from the distributed sources, but also it provides flexibility on the location choice, unlike post-combustion capture with closely bound to the sites of the industries. CO2 air capture can thus be installed in areas with currently un-productive land in food industry. Moreover, CO2 capture from air enables to create an elevated level of CO2 as carbon nutrient for the plant growth and thus increases the biomass productivity! The current study on CO2 air capture with solid sorbents a preliminary screening identified Lewatit® VP OC 1065, a mesoporous ion exchange resin (IER), with divinylbenzene crosslinked polymer with benzylamine groups on a polystyrene matrix, as potential interesting candidate for CO2 capture from the atmosphere. This sorbent shows promising thermal stability and satisfied performance in CO2 air capture. More importantly, Lewatit is a commercial product, which is favorable to fulfill the demand of sorbent in future scale-up.

Furthermore, this IER has a higher selectivity of CO2 over H2O at ambient condition compared with other physical sorbent. In addition, the presence of H2O elevates the uptake of CO2. However, the q_H2O uptake increase almost linearly with the increase of RH. Water co-adsorption has mainly three potential influences:

  1. Interferes with CO2 adsorption
  2. Sorbent stability (inhibition of urea formation, hydrothermal stability)
  3. Increases Energy demand

Part I: Investigation of the CO2 adsorption in the various RH conditions (1-1.5 months)

This part will be done in the fixed bed reactor. The experiment will be mainly focus in the temperature of 5, 10, 20, 30 and 40 °C under the range of RH of 10% - 80%. The items as follows will be derived from the experimental work:

  • Equilibrium capacity of CO2 and H2O under the studied conditions
  • An equilibrium model of CO2 air capture (5 – 40 °C) at different RH conditions (10% - 80%)
  • The influence of RH on the CO2 adsorption kinetics
  • The comparison of the dynamic in the CO2 and H2O in the adsorption and desorption (dry air/N2 purge with step-wise temperature swing will be applied in the desorption process)

Part II: Investigation of the CO2 and/or water sorption mechanisms

The study on the water sorption mechanism will focus on whether it is physical multilayer adsorption and seek for the relation between the water capacity and pore size/pore volume.

The study on the CO2 sorption mechanism in the wet condition will focus on what is the reason for the increased amount of CO2 in the wet conditions. (Physical like dissolution or chemical…)

Part III: Report writing

D:\Personal working data\04_Figures\Visio\fixed bed with water columns.emf
Figure 1. Schematic of the fixed-bed with water columns