An Efficient Solid–Liquid Biphasic Solvent for CO₂ Capture: Crystalline Powder Product and Low Heat Duty

Abstract

A nonaqueous, phase-change absorbent of 2-amino-2methyl-1-propanol (AMP)/piperazine (PZ) and environmentally friendly solvent dipropylene glycol dimethyl ether (DME) fixes a number of issues suffered by a solid−liquid biphasic solvent, such as high viscosity of the saturated solution and difficult separation and regeneration of the viscous solid. The solid phase occupies 43% of the total volume while attributes about 94% of the total loading (0.87 mol mol −1 ) of the solution. Beside the formation of AMP-carbamate and PZ-carbamate according to zwitterions mechanism, the coupling products of AMP/PZ-carbamate are also found in the crystal, which helps to reduce the desorption temperature during the regeneration. Because of low solubility, self-aggregation, and high lattice energy in DME, the CO 2 products precipitate and form a white crystalline powder in the lower phase of the solution. Meanwhile, the solid precipitation helps the bulk solution to keep a lower partial pressure and higher diffusivity of CO 2 , conforming a perfect performance of CO 2 capture into the biphasic solvent. The regeneration heat duty of the solvent (1.61 GJ t −1 CO 2 ) was approximately 57% less than that of the benchmark monoethanolamine (MEA) because of its perfect performance on CO 2 capture, such as high absorption loading, high regeneration efficiency, and low amount of rich phase required for regeneration. The novel absorbent has a great potential for green and sustainable CO 2 capture.

Review of carbon capture absorbents for CO2utilization

“…65,107,[120][121][122][123] To resolve these limitations, researchers have ventured into synthesizing novel absorbents via hybrid mixing and incorporating promoters or enhancers into CO 2 capture systems. 32,38,65,66,83,118,[124][125][126] The purpose of these initiatives is to combine the advantages of the different absorbents to enhance their CO 2 capture performance and overcome their limitations. 89,127 As numerous hybrid absorbents are being proposed over the years, this subsection only highlights some of the recent development of different hybrid absorbents.…”

“…One popular absorbent system developed is the hybrid of alkanolamines and ILs. 125,126,[128][129][130][131] In 2021, Damanafshan et al 129 analyzed the carbon capture performance of an aqueous MDEA and [Omin][BF 4 ] IL blend. It was reported that the blended absorbent can enhance CO 2 absorption capacity of approximately 0.05 to 2 mol CO 2 /mol amine compared to a typical MDEA solution.…”

“…32,65,130,170,171 The majority of the current studies only focus on the absorption (i.e., CO 2 loading capacity and reaction rate) and desorption (regeneration energy) capabilities of these novel absorbents and have yet to be coupled with a utilization potential. 125,126,129,130 Therefore, Damanafshan et al, 129 in a more recent work, pointed out that ongoing investigations on additional criteria (i.e., degradation rate, vapor pressure, corrosiveness and solvent cost) set by Budzianowski et al 135 and the respective utilization potential needs to be established to nudge the development of these novel absorbents for industrial scale-up. 139 On the other hand, CO 2 utilization pathway consideration is crucial for developing a sustainable carbon capture process.…”

“…These include toxicity of amine absorbents group and ILs, low CO 2 capture absorption rate for MDEA, limited application data of carbonate absorbents in CO 2 capture, limited direct utilization option of hydroxide absorbents and CaCO 3, and uncertainty on the post‐absorption product by amino acid salts 65,107,120–123 . To resolve these limitations, researchers have ventured into synthesizing novel absorbents via hybrid mixing and incorporating promoters or enhancers into CO 2 capture systems 32,38,65,66,83,118,124–126 . The purpose of these initiatives is to combine the advantages of the different absorbents to enhance their CO 2 capture performance and overcome their limitations 89,127 .…”

Carbon dioxide desorption intensified by metal atom

“…In order to solve this problem, nonaqueous solutions, such as AMP + dipropylene glycol dimethyl ether, 2-ethylhexan-1-amine (EHA) + diglyme, EHA + triglyme, and EHA + tetraglyme are developed to improve the CO 2 absorption performance. [18][19][20] The recent research has focused on the usage of nanofluids to improve CO 2 capture performance. [21][22][23][24] In these researches, nanofluids of graphene-oxide/MDEA, SiO 2 / methanol, and dodecane/methanol are used as CO 2 absorbent.…”