Modelling and Experimental Study of the CO2 Adsorption Behaviour of Polyaspartamide as an Adsorbent During Post-Combustion CO2 Capture

Abstract

Adsorption technology due to its potentially low energy consumption, simple operation and flexibility in design to meet different demands is fast becoming popular and is now widely considered in the area of CO2 capture. Adsorbents play a vital role in any adsorption technology. Therefore, the behavior of adsorbents under different conditions during an adsorption process needs to be investigated. In this study, the behavior of polyaspartamide as an adsorbent during post-combustion CO2 capture was investigated using kinetic and non-kinetic models. Bohart-Adams and Thomas models were the non-kinetic models explored to ascertain whether external mass transfer dominated the overall system kinetics during the CO2 adsorption onto polyaspartamide. The kinetics of adsorption of polyaspartamide was studied using Lagergen's pseudo 1st order, Lagergen's pseudo 2nd order and the Avrami kinetic models in order to understand whether the adsorption process was a physical, chemical or physiochemical process. The experimental validation of the model prediction was carried out in a laboratory-sized packed bed adsorption column at an operating pressure of 2bar; gas flow rate of 1.5-2.5ml/s, and a temperature range of 303-333K using 0.1g of the adsorbent. The experimental breakthrough curve showed a superior fit with the Bohart-Adams model. For the kinetic study, Avrami kinetic model displayed a better fit with kinetic data at all temperatures studied. The non-kinetic model revealed that external mass transfer governed the adsorption of CO2 onto polyaspartamide while the kinetic study revealed that the mechanism of adsorption of CO2 onto polyaspartamide was more of physical than chemical (physiochemical).