Influence amine type and reaction time on desorption rate

“Desorption rate provides an indication of how fast a CO2 rich amine solution can release the already absorbed CO2 at moderate or high temperatures (80–120 °C). Some researchers have used the term initial desorption rate to describe this [57][97][111][150]. Nwaoha et al. reported initial desorption rate from a laboratory scale analysis of amine solutions as the slope of the linear portion of desorption capacity (mol CO2/l-amine solution/min) vs time (minutes) graph [111]. The process of extracting the initial desorption rate is similar to that of the initial absorption rate. The only difference is that desorption process is conducted at a higher temperature where CO2 is removed from the CO2 rich amine solution instead of being added. Fig. 13 displays a typical desorption curve. The steeper the straight line (higher slope) the higher the initial desorption rate.

Fig. 13

Fig. 13. Desorption capacity vs. time plot for initial desorption rate estimation.

Comparing the hypothetical amine solutions (Amine A and Amine B) their initial desorption rates can be estimated from the slope of the first 10 and first 20 min (straight line portion of the graph) respectively. Alternatively, the initial desorption rates of both amines can be estimated based on the first 10 min alone. The choice of method will depend solely on the objective of the researcher. The reason for choosing the linear portion to determine the initial desorption rate is that as the curve starts levelling off, it reveals that the same amount of heat is supplied but very little amount of CO2 is desorbed.

Leave a Comment