CO₂-Binding Organic Liquids Comprised of 1,1,3,3-Tetramethylguanidine and Alkanol for Postcombustion CO₂ Capture: Water Inhibitory Effect of Amine Promoters

Abstract

CO 2 -binding organic liquids (CO 2 -BOLs) are switchable polarity solvents that can be used as nonaqueous green solvents for energy-efficient CO 2 capture. In this study, the novel three-component CO 2 -BOLs comprised of 1,1,3,3-tetramethylguanidine (TMG) as a superbase, an alkanol (methanol, nbutanol, sec-butanol, and 1-hexanol), and an amine (EEA, MEA, AMP, DEA, AEEA, PZ, TETA, and DETA) were introduced. Screening experiments were performed to find the best combination of solvent components based on CO 2 loading and absorption rate. The TMG/methanol/MEA BOL with a molar ratio of 0.3/0.6/0.1 was selected as the preferred solvent, which has an equilibrium absorption (α eq ) and a CO 2 uptake within 30 min (α R ) of 0.396 and 0.283 mol CO 2 /mol solvent, respectively. CO 2 -BOLs were characterized using FTIR, 1 H NMR, and 13 C NMR spectroscopy to specify the produced ionic species, explain the water inhibitory effect of MEA, and propose a plausible reaction mechanism for the reaction of CO 2 with the three-component BOLs in the absence and presence of water impurity. It was found that the addition of MEA to the two-component BOLs (base/alcohol) restricts the formation and precipitation of bicarbonate salt that leads to the lower energy consumption for solvent regeneration.

New Solvents for CO2 and H2S Removal from Gaseous Streams

“…However, several limitations have been detected. Application of some amines led to the formation of solid products, which is detrimental for practical applications [131]. Alkanolguanidines show an exponential viscosity increase at increasing CO 2 loadings (up to 103 cP at full loading); the only way to maintain the control of viscosity is to operate with limited CO 2 loadings.…”

“…Recently, CO 2 -BOLs made up of 1,1,3,3-tetramethylguanidine (TMG) as a superbase, an alkanol (methanol, n-butanol, sec-butanol, and 1-hexanol), and an amine (EEA, MEA, AMP, DEA, AEEA, PZ, TETA and DETA) were characterized in terms of absorption rate and CO 2 loading [131]. The results show that, owing to the addition of MEA, the ternary CO 2 -BOL made up of methanol-TMG and MEA does not form any bicarbonate salt, which limits the regeneration efficiency and the solvent applicability.…”

Carbon dioxide capture by new DBU‐based DES: The relationship between ionicity and absorptive capacity

“…Recently, Zhang et al 36 found that all parts of 1,5‐Diazabicyclo[4.3.0]non‐5‐ene (DBN)‐BmimCl‐Im have a synergistic effect, and the protonated superbase plays a key role in absorption. Hedayati Ali et al 37 reported the organic liquids combined with CO 2 are non‐aqueous green solvents for CO 2 capture, and 1,1,3,3‐tetramethylguanidine (TMG)/methanol/monoethanolamine (MEA) binding organic liquid (BOL) was selected as the best solvent. In addition, Zhu et al 13 proved that DBU as a cation has excellent CO 2 capture and recycling capacity.…”

Binary System of Polyethylene Glycol 200 (1) + 3-Dimethylamino-1-propylamine (2) for CO2 Absorption: Thermophysical Properties and Spectroscopic Study

“… 3 , 4 Various methods have been proposed to capture CO 2 , such as solid adsorption, 5 , 6 membrane separation, 7 , 8 and organic solvent scrubbing. 9 − 11 The organic solvent scrubbing method involves either physical or chemical solvents according to the strength of the solvent–solute interaction. Representative amine scrubbing is the most commonly used commercial technology for CO 2 capture through chemical absorption.…”

“…The extensive use of fossil fuels and the rapid increase of CO 2 content in the atmosphere have caused the greenhouse effect and the negative consequences of global climate changes, and this has attracted widespread attention. , Experts generally deem CO 2 capture and utilization (CCU) to be one of the most effective methods to reduce global CO 2 emissions. , Various methods have been proposed to capture CO 2 , such as solid adsorption, , membrane separation, , and organic solvent scrubbing. − The organic solvent scrubbing method involves either physical or chemical solvents according to the strength of the solvent–solute interaction. Representative amine scrubbing is the most commonly used commercial technology for CO 2 capture through chemical absorption. , However, the loss of amine by volatilization easily causes secondary pollution in the process of CO 2 removal.…”