Evaluation of the novel biphasic solvents for CO 2 capture: Performance and mechanism

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Nonaqueous amines are currently being explored for energy-efficient postcombustion CO2 capture, but the absorption capacity and regeneration efficiency of most absorbents still need to be further improved. In this work, a mixture of triethylene tetramine (TETA) and 2-amino-2-methyl-1-propanol (AMP) dissolved in ethanol was chosen as a nonaqueous absorbent for CO2 capture and performed with high absorption loading and regeneration efficiency. In addition, the changes of the components during the absorption–desorption process and reaction mechanisms of nonaqueous absorbents were explored by 13C NMR spectroscopy and compared with those of aqueous absorbents. The results showed that TETA/AMP/ethanol had higher absorption loading and regeneration efficiency (3.71 mol kg–1, 95.4%) after the fifth regeneration cycle than TETA/AMP/water (3.54 mol kg–1, 38.8%) when the amine mass concentration was 40 wt %. CO2 capture by TETA/AMP aqueous and nonaqueous solutions proceeded by two different mechanisms. Polycarbamate and alkyl carbonate of C2H5OCO2 – formed in the TETA/AMP/ethanol solution, while polycarbamates and HCO3 –/CO3 2– formed in the TETA/AMP/water solution. Moreover, the regeneration efficiency of the nonaqueous solution was higher than that of the aqueous solution because the reaction products were easily decomposed in ethanol, and the regeneration consumption of the organic solvent was lower than that of water.

Section: Resultssupporting

confidence: 90%

Performance and Mechanisms of Triethylene Tetramine (TETA) and 2-Amino-2-methyl-1-propanol (AMP) in Aqueous and Nonaqueous Solutions for CO₂ Capture

Liu

Jing

Zhou

et al. 2017

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“…To solve the highly energy intensive stripper issue, various research efforts have been reported. The bulk of the literature has been published in the past two decades and includes screening new amine solvents; suggesting new techniques for solvent regeneration; inventing new blended solvents and biphasic solvents; modifying process configurations; and adding activated particles to aid absorption/desorption. − Though adopting some of these techniques has helped minimize the heat requirement for solvent regeneration, that requirement has not reached an acceptable range . An important point to consider for a worldwide deployment of amine-based post-combustion CO 2 capture technique is that a solvent with favorable characteristics will have to be manufactured in annual quantities of 1 Mton or greater .…”

Section: Introductionmentioning

confidence: 99%

Performance and Mechanism of Metal Oxide Catalyst-Aided Amine Solvent Regeneration

Bhatti

Nam

Park

et al. 2018

CO 2 capture from flue gas using the amine-based postcombustion technique is costly because of the high energy requirement for solvent regeneration. The addition of catalyst to the regeneration step can overcome this drawback. In this study, we investigate the regeneration performance of CO 2 -rich MEA solution without and with two solid metal oxide catalystsZrO 2 and ZnOwithin a temperature range of 40−86 °C. The solvent regeneration performance was evaluated in terms of CO 2 desorption rate, total amount of desorbed CO 2 , solvent cyclic capacity, and CO 2 -lean loadings achieved from the catalytic solutions in comparison with the noncatalytic MEA solution.To understand and support the obtained results BET, NH 3 −TPD, pyridine−FTIR, and 13 C NMR characterization techniques are performed. The obtained results suggest that both catalysts are capable of optimizing the solvent regeneration by desorbing up to 32% greater amounts of CO 2 , improving the CO 2 desorption rate up to 54%, and increasing the solvent cyclic capacity up to 56%. On the basis of the obtained experimental and characterization results, a possible mechanism for metal oxide catalyst-aided MEA regeneration process is proposed. The stabilities of both catalysts are confirmed by 5 cyclic solvent regeneration experiments. Additionally, by studying the CO 2 absorption in MEA in the presence of catalyst, it has been investigated if the catalysts induce any undesired activity in the CO 2 absorption step. Catalytic regeneration of amine solvent can pace up the construction of largescale CO 2 capture plants by economizing the process.

“…As for tertiary amine, e.g., PMDETA, it cannot directly react with CO 2 but can act as a catalyst to catalyze the hydration of CO 2 . The reaction is considered as a single-step reaction …”

Section: Materials and Methodsmentioning

confidence: 99%

“…As a result, energy consumption can be remarkably reduced due to a smaller amount of solution for regeneration. , A case in point is the DMX phase-changing solvent developed by IFP Energies Nouvelles, which could reach a reboiler heat duty of 2.1 GJ·ton –1 CO 2 , much lower than the 3.7 GJ·ton –1 CO 2 requirement of the 30 wt % MEA process. , Another biphasic solvent composed of 3-(methylamino) propylamine (MAPA) and diethylethanolamine (DEEA) could also remarkably reduce the specific reboiler heat duty to around 2.2–2.4 GJ·ton –1 CO 2 . More recently, some newly emerging bisolvent biphasic solvents, such as 1,4-butanediamine (BDA) and DEEA blend, N , N -dimethylbutylamine (DMBA) and DEEA blend, triethylenetetramine (TETA) and dimethylcyclohexylamine (DMCA) blend, diethylenetriamine (DETA) and pentamethyldiethylenetriamine (PMDETA) blend, and TETA and N,N,N′,N’ -tetramethyl-1,3-propanediamine (TMPDA) blend, have been investigated for further improving the energy requirement of solvent regeneration. In our previous work, a novel trisolvent biphasic solvent of DETA, 2-amino-2-methyl-1-propanol (AMP), and PMDETA was developed for the purpose of energy-saving CO 2 capture .…”

Section: Introductionmentioning

confidence: 99%

Kinetics and Thermodynamics of CO₂ Absorption into a Novel DETA-AMP-PMDETA Biphasic Solvent

Zhou

et al. 2019

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A novel biphasic solvent consisting of diethylenetriamine (DETA), 2-amino-2-methyl-1-propanol (AMP), and pentamethyldiethylenetriamine (PMDETA) is considered as a promising CO2-capturing candidate because of its high absorption capacity, favorable phase separation behavior, fast desorption rate, and high cyclic capacity. In the present work, reaction kinetics and thermodynamics of CO2 absorption into the DETA-AMP-PMDETA biphasic solvent were studied. The kinetics process of CO2 absorption was described using the zwitterion mechanism and invoking the two-film theory. Under the fast pseudo-first-order regime, kinetics parameters, e.g., overall reaction rate constant (k ov,mix), second-order rate constant (k 2,mix), and enhancement factor (E), were determined. Kinetics results indicated that the CO2 reaction rate was mainly determined by DETA and AMP in the biphasic system, while PMDETA molecules would aggregate to form PMDETA clusters, which limited the absorption of CO2 to a certain extent. On the other hand, thermodynamics results showed that the regeneration heat of DETA-AMP-PMDETA biphasic solvents could be significantly reduced compared with that of MEA. In particular, the regeneration heat of the solvent 0.5 mol·L–1 (M) DETA + 1.5 M AMP + 3 M PMDETA (0.5D1.5A3P) was only 1.83 GJ·ton–1 CO2, which was approximately 52% lower than that of 30 wt % MEA. This finding suggested that the DETA-AMP-PMDETA biphasic solvent may be a good alternative to MEA to advance energy-efficient and economical CO2 capture.