Post-combustion CO2 capture and separation in flue gas based on hydrate technology:A review
Introduction
Due to the widespread use of fossil fuels in the world, the CO2 content in the atmosphere is sharply increasing and global warming is posing a serious threat to the global environment [1,2]. Power plants are the key contributors to CO2 emissions, accounting for approximately 41% of the global CO2 release, which is increasing on an annual basis [3]. The gas products after complete combustion in the power plant contain approximately 20% of CO2 and 5% of O2, less than 1% of H2S, a large amount of water vapor, and the rest are mainly N2 [4]. How to effectively separate CO2 from flue gas and store it is a global concern. Traditional methods of CO2 capture and separation include membrane separation, chemical adsorption, and physical adsorption [[5], [6], [7][5], [6], [7][5], [6], [7]]. Studies have also proposed that the above methods results in serious pollution, high cost, low efficiency and a series of problems [8]. Therefore, a method of converting CO2 to hydrates was proposed [[9], [10], [11], [12][9], [10], [11], [12][9], [10], [11], [12]].
Gas hydrate is an ice-like crystalline substance formed by natural gas and water under high pressure and low temperature [13,14]. Gas hydrate has three host structures, including cubic structure I (sI), cubic structure II (sII), and cubic structure H (sH) [15]. The crystal structure parameters of these three types of gas hydrate are shown in Table 1. When the flue gas is converted to hydrate, CO2 easily forms sI hydrate [16,17] at low pressures and 273 K, while N2 produces sII hydrate at the same temperature and a pressure of 15.9 MPa [18,19]. Special attention should be paid to the fact that the hydrate formation conditions of N2 and O2 in flue gas are similar [4], and the content of H2S gas is low. When studying the hydrate method to capture and separate CO2 in flue gas, the binary mixture gas with 20 mol% CO2 and 80 mol% N2 is mostly used to simulate flue gas, which is different from the real flue gas composition. As shown in Fig. 1, due to the differences in phase equilibria between CO2 and N2, CO2 preferentially generates CO2 hydrate. This is also the theoretical basis for separating CO2 from flue gas using hydrate technology. However, the formation process of hydrate is a complex phase transition process and requires low temperature and high pressure conditions [20] accompanied by gas-liquid mass transfer and heat transfer [21], thus restricting the development of CO2 capture and separation technology in flue gas by the hydrate method to a certain extent. At present, CO2 capture by the hydrate method is mainly faced with the challenges of harsh conditions, low rates, poor CO2 recovery and low gas consumption.
To date, many different methods have been used to promote the formation of gas hydrates, such as stirring [23], spraying [24], injecting gas as bubbles [25], and applying ultrasonic waves [26]. In addition, adding thermodynamic accelerators such as tetrahydrofuran (THF) [[27], [28], [29]], tetra-n-butylammonium bromide (TBAB) [8,[30], [31], [32]], cyclopentane (CP) [10], and sulfonated lignin [33] to the reaction system can reduce the temperature and pressure required for CO2 hydrate formation and accelerate the formation process. Studies have also found that the presence of surfactants, such as sodium dodecyl sulfonate (SDS) [[34], [35], [36]], can effectively improve the mass transfer between the gas and liquid phases and promote gas dissolution. Other researchers have used biosurfactants [[37], [38], [39]] to promote the formation of hydrates. In addition, nanofluids, which allow for high heat and mass transfer, were proposed at the end of the 20th century and considered to be a suitable additive for hydrate formation [40]. In 2006, Li et al. [41] proved that copper nanofluids can promote the formation of HFC134a hydrate. This was the first time that nanofluids were shown to promote the formation of hydrate. In subsequent studies, an increasing number of nanofluids and mixed fluids of nanomaterials with surface additives were found to play an important role in promoting hydrate formation [[42], [43], [44], [45], [46], [47], [48], [49], [50][42], [43], [44], [45], [46], [47], [48], [49], [50][42], [43], [44], [45], [46], [47], [48], [49], [50]]. However, although a large number of additives have been applied to the separation of CO2 and N2 in the flue gas, the mechanism of action of the different additives remained unclear and there was no unified understanding of an optimal additive.
In a previous review [51], the characteristics of hydrates with different thermodynamic additives were summarized in detail, and the efficiency of capturing and separating CO2 from flue gas was also summarized. However, the effect of different additives on the mechanism of action of CO2 separation was not explained, and there was no unified conclusion regarding the application of additives. In addition, the impact of different industrial processes on CO2 capture and separation for commercial application of this technology was not mentioned. Therefore, in this review, we compared the effects of different chemical additives on CO2/N2 separation by summarizing the existing research results and obtain the current optimal additive types. In addition, we also analyze the mechanism of action of different additives. Furthermore, regarding the application of CO2 capture and separation technology based on hydrate technology, we also summarize the influence of pressure, temperature, inlet flow rate and other technological processes on the capture effect. Finally, we propose unique suggestions addressing the limitations of the current technology.
Section snippets
Experimental parameters
The hydrate induction time refers to the time required for the hydrate formation, which includes an exothermic event leading to a brief temperature increase of the system in the process of the experiment; the formation of hydrate crystals can also accelerate the gas consumption, resulting in a sudden decrease in the system pressure, which causes the commonly used temperature to suddenly increase and the pressure to decrease during the induction time of hydrate formation.
The total gas
The effect of chemical additives on CO2 hydrate formation
In the process of CO2 hydrate formation, the presence of chemical additives can effectively improve the temperature and pressure conditions required for hydrate formation, increase the consumption of CO2 and shorten the induction time of hydrate formation. Common chemical additives include thermodynamic and kinetic additives. Many researchers have studied their effects on the formation of CO2 hydrate. This section summarizes the previous research results and elaborates the mechanism of the
Limitations and development
The capture and separation of CO2 in flue gas based on the hydrate method has been proven effective. The experimental results showed that chemical additives could improve the effectiveness of CO2 capture and separation by changing the phase equilibrium condition of the hydrate, reducing the surface tension of the solution, and accelerating the dissolution of CO2. However, experimental studies mainly focused on the changes in the hydrate formation conditions caused by thermodynamic additives. At
Conclusion
This review summarizes the effects of different chemical additives on CO2 capture and separation in flue gas by hydrate method. It systematically analyzes the mechanism of all the additives involved in accelerating CO2 capture. Thermodynamic additives can broaden the stable region of hydrate formation and be affected by its concentration. Among them, the single TBAF has the most substantial separation effect on CO2, and the separation factor reached by 37, which is more environmentally friendly
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
This work is financially supported by the National Key Research and Development Program of China (2019YFC0312304), the National Natural Science Foundation of China (No.52176057, 51976023, 52076032), Dalian Leading Academic & Key Plan Project (Grant No. 2020JJ25CY010), the Natural Science Foundation of Liaoning Province (Grant No. 2019-MS-061), and the Fundamental Research Funds for the Central Universities (Grant No. DUT20RC(5)003).
References (116)
- et al.
Progress and trends in CO2 capture/separation technologies: a review
Energy
(2012) IEA world energy outlook 2011 — a comment
Energy Pol
(2012)- et al.
Thermodynamic analysis of hydrate-based pre-combustion capture of CO2
Chem Eng Sci
(2009) - et al.
Adsorption characteristics of CH4 and CO2 in organic-inorganic slit pores
Fuel
(2020) - et al.
Recent advances in gas hydrate-based CO2capture
J Nat Gas Sci Eng
(2015) - et al.
Clathrate hydrate capture of CO2 from simulated flue gas with cyclopentane/water emulsion
Chin J Chem Eng
(2010) - et al.
CO2capture by hydrate formation in quiescent conditions: in search of efficient kinetic additives
Energy Procedia
(2011) - et al.
CO2 capture by hydrate crystallization - a potential solution for gas emission of steelmaking industry
Energy Convers Manag
(2007) - et al.
Review of natural gas hydrates as an energy resource: prospects and challenges
Appl Energy
(2016) - et al.
ScienceDirect Phase equilibria in the H 2 O – CO 2 system between 250 – 330 K and 0 – 1 . 7 GPa : stability of the CO 2 hydrates and H 2 O-ice VI at CO 2 saturation
(2013)
Mech gas Hydrate Formation Inhibition
Study on the kinetics of hydrate formation in a bubble column
Chem Eng Sci
Study on methane hydrate formation using ultrasonic waves
J Ind Eng Chem
Hydrate phase equilibria of the guest mixtures containing CO2, N2 and tetrahydrofuran
Fluid Phase Equil
Study on the influence of SDS and THF on hydrate-based gas separation performance
Chem Eng Res Des
CO2 hydrate formation at atmospheric pressure using high efficiency absorbent and surfactants
Energy
CO2 capture from binary mixture via forming hydrate with the help of tetra-n-butyl ammonium bromide
J Nat Gas Chem
Efficient CO2 capture from a simulated shale gas using tetra-n-butylphosphonium bromide semiclathrate hydrate
Energy Procedia
Impacts of the surfactant sulfonated lignin on hydrate based CO2 capture from a CO2/CH4 gas mixture
Energy
Effect of surfactant on the formation and dissociation kinetic behavior of methane hydrate
Chem Eng Sci
Effect of three representative surfactants on methane hydrate formation rate and induction time
Egypt J Pet
Surfactant effects on gas hydrate formation
Chem Eng Sci
Investigations into surfactant/gas hydrate relationship
J Petrol Sci Eng
Kinetic study of carbon dioxide hydrate formation in presence of silver nanoparticles and SDS
Chem Eng J
Kinetic study of carbon dioxide hydrate formation in presence of silver nanoparticles and SDS
Chem Eng J
Fluid Phase Equilibria Effect of graphite nanoparticles on CO 2 hydrate phase equilibrium
Fluid Phase Equil
A study on the influence of nanofluids on gas hydrate formation kinetics and their potential: application to the CO2 capture process
J Nat Gas Sci Eng
Review of fundamental properties of CO2 hydrates and CO2 capture and separation using hydration method
Renew Sustain Energy Rev
Gas hydrate formation from hydrogen/carbon dioxide and nitrogen/carbon dioxide gas mixtures
Chem Eng Sci
The clathrate hydrate process for post and pre-combustion capture of carbon
dioxide
A new apparatus to enhance the rate of gas hydrate formation: application to capture of carbon dioxide
Int J Greenh Gas Control
Semiclathrate-based CO 2 capture from flue gas mixtures : an experimental approach with thermodynamic and Raman spectroscopic analyses
Appl Energy
Promotion of hydrate-based CO 2 capture from fl ue gas by additive mixtures ( THF ( tetrahydrofuran ) þ TBAB ( tetra-n-butyl ammonium bromide ))
Energy
International Journal of Greenhouse Gas Control Hydrate-based pre-combustion capture of carbon dioxide in the presence of a thermodynamic promoter and porous silica gels
Int J Greenh Gas Control
Experimental investigation of incipient equilibrium conditions for the formation of semi-clathrate hydrates from quaternary mixtures of ( CO 2 + N 2 + TBAB + H 2 O )
J Chem Thermodyn
Fluid Phase Equilibria Phase equilibrium measurements for semi-clathrate hydrates of the ( CO 2 + N 2 + tetra-n-butylammonium bromide ) aqueous solution systems : Part 2
Fluid Phase Equil
Phase equilibrium measurements for semi-clathrate hydrates of the ( CO 2 + N 2 + tetra-n-butylammonium bromide ) aqueous solution system
J Chem Thermodyn
Separation processes for carbon dioxide capture with semi-clathrate hydrate slurry based on phase equilibria of CO2 + N2 + tetra-n-butylammonium bromide + water systems
Chem Eng Res Des
Semiclathrate-based CO 2 capture from flue gas mixtures : an experimental approach with thermodynamic and Raman spectroscopic analyses
Appl Energy
Recent advances in gas hydrate-based CO2 capture
J Nat Gas Sci Eng
Study on the influencing factors of gas consumption in hydrate-based CO2 separation in the presence of CP by Raman analysis
Energy
Surfactant effects on hydrate formation in an unstirred gas/liquid system : an experimental study using methane and sodium alkyl
sulfates
Study on the influence of SDS and THF on hydrate-based gas separation performance ଝ
Chem Eng Res Des
Carbon dioxide hydrate formation with SDS : further insights into mechanism of gas hydrate growth in the presence of surfactant
Fuel
Effects of additive mixtures ( THF/SDS ) on carbon dioxide hydrate formation and dissociation in porous media
Chem Eng Sci
Fluid Phase Equilibria Hydrate phase equilibrium measurements for ( THF + SDS + CO 2 + N 2 ) aqueous solution systems in porous media
Fluid Phase Equil
Dispersion behavior and thermal conductivity characteristics of Al2O3–H2O nanofluids
Curr Appl Phys
Numerical simulation of free convection based on experimental measured conductivity in a square cavity using Water/SiO2 nanofluid
Int Commun Heat Mass Tran
International journal of heat and mass transfer thermal conductivity measurement of methanol-based nanofluids with Al 2 O 3 and SiO 2 nanoparticles
Int J Heat Mass Tran
Trends in global CO2 and total greenhouse gas emissions: summary of the 2017 report
Cited by (52)
A comprehensive review of semi-clathrate hydrates for CO<inf>2</inf> capture: Characterizations, mechanism and role of promoters
2024, Carbon Capture Science and TechnologyEfficient CO<inf>2</inf> capture and in-situ electrocatalytic conversion on MgO surface by metal single-atom engineering: A comprehensive DFT study
2024, Separation and Purification TechnologyMembranes for CO<inf>2</inf> capture and separation: Progress in research and development for industrial applications
2024, Separation and Purification Technology