Development and Characterization of New Sorbent Systems for CO2 Post-Combustion Capture

  • Adewale Ayodeji Adeosun

Student thesis: Master's Thesis

Abstract

Global warming is one of the key challenges facing humanity in 21st century and carbon dioxide (CO2) accounts for 63.5% of the positive radiative forcing. Therefore, it is imperative to control the emission of CO2 into the atmosphere in order to mitigate global warming impacts. Among the technological solutions, carbon dioxide capture & storage (CCS) technology will be responsible for 19% reduction in carbon dioxide emission by 2050 and post-combustion CO2 capture using chemical absorption processes is the near-term CCS option of direct applications to large stationary CO2 sources such as power plants. However, CCS technology is not yet economically feasible for industrial deployment due to high capital and operational cost. Since good absorption capacity and absorption rate imply lower capital and operational cost, it is believed that key challenges to post-combustion capture technology deployment can be solved by developing novel solvents. Therefore, the author explored the strengths of various classes of amine (primary, secondary, tertiary, sterically-hindered and cyclic amines) in an attempt to develop new solvents. Preliminary evaluation through process simulation using AspenĀ® plus software was done for commercially available amines and their blends. In addition, experimental works using solvent screening set-up, wetted wall column set-up, parr pressure and vapour-liquid equilibrium reactors were performed for novel blends. From the process simulation results for amine blends, using existing thermodynamic data but with a modification of the reaction steps, a blend of 25% 2-amino, 2-methylpropanol (AMP) in 5% diethanolamine activation was the best with respect to solvent flow rate and reboiler duty with values of 14.882m3/ton-CO2 and 3.03GJ/ton-CO2 respectively and cyclic loading of 0.474. However, a blend of 25wt% AMP in 5wt% monoethanolamine (MEA) activation was the best with respect to cyclic loading capacity of 0.58 at solvent lean loading of 0.10. Both blends showed better results than 30wt% MEA in all output parameters measured. From a total of 27 novel blends, four promising piperazine-based blends were found from the experimental works in terms of CO2 absorption capacities and rates using the solvent screening set-up, phosphoric acid titration set-up and vapour-liquid equilibrium set-up. The author also developed and characterized three novel combinations of 3-piperidinemethanol (3PM), which is a cyclic monoamine, in MEA activation using wetted wall column and parr pressure vapour-liquid reactor set-ups. This work has shown that improved performance parameters such as high cyclic capacity, high CO2 absorption capacity, high CO2 absorption rate, low absorption enthalpy can be obtained by novel combination of amines. Such improved performance will lead to eventual post-combustion capture deployment and applications.
Date of Award2013
Original languageAmerican English
SupervisorMohammad Abu Zahra (Supervisor)

Keywords

  • monoethanolamine
  • piperazine
  • 3-piperidinemethanol
  • cyclic loading
  • absorption capacity
  • absorption rate
  • absorption enthalpy

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