Continuous separation of CO2 from a H2 + CO2 gas mixture using clathrate hydrate

Shunsuke Horii, Ryo Ohmura

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

CO2 capture using clathrate hydrates is an environmentally friendly separation technology. When considering operational efficiency, it is desirable to operate the separation process continuously. In this experimental study, the continuous separation of CO2 from a model fuel gas was performed for H2 + CO2 + H2O and H2 + CO2 + tetra-n-butylammonium bromide (TBAB) + H2O systems with TBAB mass fractions of wTBAB = 0, 0.05, 0.10, and 0.32. Measurements were taken to track the time evolution of compositions of the gas phase and hydrate slurry. After between 37 and 48 h from the start of the experiment, H2 compositions in the gas phase reached steady state values of 0.87, 0.81, and 0.78 for wTBAB values of 0, 0.05, and 0.10, respectively. For the same conditions, CO2 compositions in the hydrate slurry reached steady state values of 1.00, 0.82, and 0.79, respectively. In carrying out this work we have shown that it is possible to successfully separate CO2 using structure I hydrates and ionic semiclathrate hydrates, on a continuous basis. There is the caveat, however, that for wTBAB = 0.32 a continuous separation process is not possible. The split fraction of CO2 we attained were 0.76, 0.64, and 0.62 for wTBAB values of 0, 0.05, and 0.10, respectively. The water system (wTBAB = 0) exhibited the highest H2 compositions in the gas phase, highest CO2 compositions in the hydrate slurry, and highest split fraction of CO2. Although short-term operation, specifically 18 h, is possible with wTBAB = 0, continuous hydrate formation cannot be implemented. The concentration of captured CO2 for wTBAB = 0 was comparable to that obtained from hydrate-based gas separation in multistage processes or chemical absorption.

Original languageEnglish
Pages (from-to)78-84
Number of pages7
JournalApplied Energy
Volume225
DOIs
Publication statusPublished - 2018 Sep 1

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clathrate
Hydrates
Gas mixtures
slurry
gas
bromide
Chemical analysis
Gases
experimental study
gas mixture
Gas fuels
experiment

Keywords

  • Clathrate hydrate
  • CO separation
  • Ionic semiclathrate hydrate
  • Pre-combustion capture
  • Tetra-n-butylammonium bromide (TBAB)

ASJC Scopus subject areas

  • Building and Construction
  • Energy(all)
  • Mechanical Engineering
  • Management, Monitoring, Policy and Law

Cite this

Continuous separation of CO2 from a H2 + CO2 gas mixture using clathrate hydrate. / Horii, Shunsuke; Ohmura, Ryo.

In: Applied Energy, Vol. 225, 01.09.2018, p. 78-84.

Research output: Contribution to journalArticle

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N2 - CO2 capture using clathrate hydrates is an environmentally friendly separation technology. When considering operational efficiency, it is desirable to operate the separation process continuously. In this experimental study, the continuous separation of CO2 from a model fuel gas was performed for H2 + CO2 + H2O and H2 + CO2 + tetra-n-butylammonium bromide (TBAB) + H2O systems with TBAB mass fractions of wTBAB = 0, 0.05, 0.10, and 0.32. Measurements were taken to track the time evolution of compositions of the gas phase and hydrate slurry. After between 37 and 48 h from the start of the experiment, H2 compositions in the gas phase reached steady state values of 0.87, 0.81, and 0.78 for wTBAB values of 0, 0.05, and 0.10, respectively. For the same conditions, CO2 compositions in the hydrate slurry reached steady state values of 1.00, 0.82, and 0.79, respectively. In carrying out this work we have shown that it is possible to successfully separate CO2 using structure I hydrates and ionic semiclathrate hydrates, on a continuous basis. There is the caveat, however, that for wTBAB = 0.32 a continuous separation process is not possible. The split fraction of CO2 we attained were 0.76, 0.64, and 0.62 for wTBAB values of 0, 0.05, and 0.10, respectively. The water system (wTBAB = 0) exhibited the highest H2 compositions in the gas phase, highest CO2 compositions in the hydrate slurry, and highest split fraction of CO2. Although short-term operation, specifically 18 h, is possible with wTBAB = 0, continuous hydrate formation cannot be implemented. The concentration of captured CO2 for wTBAB = 0 was comparable to that obtained from hydrate-based gas separation in multistage processes or chemical absorption.

AB - CO2 capture using clathrate hydrates is an environmentally friendly separation technology. When considering operational efficiency, it is desirable to operate the separation process continuously. In this experimental study, the continuous separation of CO2 from a model fuel gas was performed for H2 + CO2 + H2O and H2 + CO2 + tetra-n-butylammonium bromide (TBAB) + H2O systems with TBAB mass fractions of wTBAB = 0, 0.05, 0.10, and 0.32. Measurements were taken to track the time evolution of compositions of the gas phase and hydrate slurry. After between 37 and 48 h from the start of the experiment, H2 compositions in the gas phase reached steady state values of 0.87, 0.81, and 0.78 for wTBAB values of 0, 0.05, and 0.10, respectively. For the same conditions, CO2 compositions in the hydrate slurry reached steady state values of 1.00, 0.82, and 0.79, respectively. In carrying out this work we have shown that it is possible to successfully separate CO2 using structure I hydrates and ionic semiclathrate hydrates, on a continuous basis. There is the caveat, however, that for wTBAB = 0.32 a continuous separation process is not possible. The split fraction of CO2 we attained were 0.76, 0.64, and 0.62 for wTBAB values of 0, 0.05, and 0.10, respectively. The water system (wTBAB = 0) exhibited the highest H2 compositions in the gas phase, highest CO2 compositions in the hydrate slurry, and highest split fraction of CO2. Although short-term operation, specifically 18 h, is possible with wTBAB = 0, continuous hydrate formation cannot be implemented. The concentration of captured CO2 for wTBAB = 0 was comparable to that obtained from hydrate-based gas separation in multistage processes or chemical absorption.

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