Carbon capture by physical adsorption: Materials, experimental investigations and numerical modeling and simulations - A review

a b s t r a c t Carbon dioxide emissions must be stabilized to mitigate the unfettered release of greenhouse gases into the atmosphere. The removal of carbon dioxide from flue gases, an important first step in addressing the problem of CO2 emissions, can be achieved through adsorption separation technologies. In most adsorption processes, the adsorbent is in contact with fluid in a fixed bed. Fixed-bed column mathematical models are required to predict the performance of the adsorptive separation of carbon dioxide for optimizing design and operating conditions. A comprehensive mathematical model consists of coupled partial differential equations distributed over time and space that describe material, energy, and the momentum balances together with transport rates and equilibrium equations. Due to the complexities associated with the solution of a coupled stiff partial differential equation system, the use of accurate and efficient simplified models is desirable to decrease the required computational time. The simplified model is primarily established based on the description of mass transfer within adsorption systems. This paper presents a review of efforts over the last three decades toward mathematical modeling of the fixed-bed adsorption of carbon dioxide. The nature of various gas–solid equilibrium relationships as well as different descriptions of the mass transfer mechanisms within the adsorbent particle are reviewed. In addition to mass transfer, other aspects of adsorption in a fixed bed, such as heat and momentum transfer, are also studied. Both single- and multi-component CO2 adsorption systems are discussed in the review. © 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

A review of mathematical modeling of fixed-bed columns for carbon dioxide adsorption

Atmospheric warming due to greenhouse gases has become a serious global concern. Extensive efforts are being made to combat this phenomenon through Carbon Capture as carbon dioxide is its major contributor. In this work, a comprehensive review has been made on various Carbon Capture methodologies including adsorption, absorption, membrane separation, Chemical Looping Combustion, cryogenic separation with focus on their process chemistry, critical process parameters, contactor configurations, kinetics, thermodynamics, process development and scale-up. The challenges at the research and development stages have also been identified so as to provide the future directions for research.

A journey into the process and engineering aspects of carbon capture technologies

The adsorption dynamics of a layered bed packed with activated carbon and zeolite 5A were studied experimentally and theoretically through breakthrough experiments and two-bed pressure swing adsorption (PSA) processes by using coke oven gas (56.4 vol.% H{sub 2}; 26.6 vol.% CH{sub 4}; 8.4 vol.% CO; 5.5 vol.% N{sub 2}; and 3.1 vol.% CO{sub 2}). The results of breakthrough curves of a layered bed showed an intermediate behavior of those of zeolite-5A bed and activated carbon bed, because each concentration front propagates with its own wavefront velocity in each layer by a different adsorption equilibrium. Since a fast and dispersed mass-transfer zone of CO in the zeolite layer of a layered bed leads to a long leading front of the N{sub 2} wavefront, controlling the leading wavefront of the N{sub 2} plays a very important role in obtaining a high-purity product and in determining the optimum carbon ratio of a PSA process for H{sub 2} recovery from coke oven gas. The layered bed PSA process was simulated in a simplified form of two single-adsorbent beds linked in series. The dynamic model incorporating mass, energy, and momentum balances agreed well with the experimental data. Concentration profiles inside the adsorption bed were alsomore » investigated.« less

Adsorption dynamics of a layered bed PSA for H2 recovery from coke oven gas

Packed bed breakthrough experiments are reported for commercial zeolite 13X and 3-aminopropyl-functionalized SBA-15 silica materials with three different amine loadings. Mass and heat transfer dynamics for all four materials are modeled successfully. Amine adsorbents with open pores are found to exhibit faster mass diffusion rates compared to zeolite 13X. When amine loading is increased by coupling aminopropyl groups, premature breakthrough combined with a long tail is observed. Contrary to conventional physisorbants, finite heat losses to the column wall do not explain the long breakthrough tail. A rate model that accounts for heterogeneity in diffusion was found to accurately capture the breakthrough shape of the high loading material. Batch uptake measurements support the hypothesis that slow diffusion through the polymer phase is what hampers adsorption kinetics in the high amine loading adsorbent. The results emphasize the importance of designing materials that are not overloaded with amine sites, as...

Jae Ho Jun

Papers

Fixed-bed adsorption for bulk component system. Non-equilibrium, non-isothermal and non-adiabatic model