Modeling of Carbon Dioxide Adsorption onto Ammonia-Modified Activated Carbon: Kinetic Analysis and Breakthrough Behavior

Abstract

The removal of carbon dioxide from the flue gas of fossil-fueled power plants can be achieved using adsorption separation technologies. In this study, the breakthrough adsorption of CO2 on fixed beds of commercial granular activated carbon (GAC) and ammonia-modified GAC (OXA-GAC) adsorbents was measured. The breakthrough curves were acquired from dynamic column measurements at temperatures ranging from 30 to 60 °C with a feed gas flow rate that varied from 50 to 100 mL min–1 and a total pressure of 1.0 atm. An earlier breakthrough time and lower dynamic adsorption capacity were observed with increasing temperature, increasing feed flow rate, and the use of the GAC adsorbent. The largest CO2 equilibrium dynamic capacity (0.67 mol kg–1) and breakthrough time (10.9 min) over the range of operating conditions investigated were obtained using OXA-GAC adsorbent at 30 °C under a 50 mL min–1 feed flow rate. To predict the breakthrough behavior of the fixed-bed adsorption of CO2, a simple model based on mass balance was developed. This model consists of an Avrami equation to describe the kinetics of adsorption and a semiempirical Toth equation to represent the gas–solid equilibrium isotherm. The Avrami equation was selected because it provided the best fit with the experimental kinetic curves for both adsorbents, with average relative errors of less than 2% over the temperature range of 30–60 °C. The resultant set of coupled differential equations was solved using a numerical approach based on the finite element method implemented in COMSOL Multiphysics software. The findings showed that the model predictions successfully fit the experimental data over the studied range of feed gas flow rates and adsorption temperatures.

Kinetics of CO2 adsorption on cherry stone-based carbons in CO2/CH4 separations

“…Moreover, the calculated values of the kinetic rate constants for the biomass based activated carbons (0.2 min -1 < k A < 0.6 min -1 ) are consistent with values reported in the literature for activated carbons [58].…”

Adsorption Kinetics and Breakthrough of Carbon Dioxide for the Chemical Modified Activated Carbon Filter Used in the Building

“…Also, qe calculated values conform well with the experimental data. The rate coefficient k2 of the pseudo-second-order rate model is figured versus CO2 initial concentration and is shown, the relation is not a simple function between k2 and C0 [29,30]. …”

Velocity variation effect in fixed bed columns: A case study of CO2 capture using porous solid adsorbents

“…Zwiebel showed that considering velocity variations due to pressure drop improves the agreement with experimental data by 5–10%, especially in the tail end of the breakthrough curves. Nevertheless, models assuming constant velocity have been used to describe CO 2 separation from mixtures (15–25% CO 2 in CO 2 /N 2 mixtures), with <2–9.5% differences compared to the experimentally measured breakthrough curves. These deviations have been attributed to errors associated with the experimental procedure or model parameters estimation.…”