The Maxwell-Stefan approach to mass transfer

Global warming resulting from the emission of greenhouse gases, especially CO2, has become a widespread concern in the recent years. Though various CO2 capture technologies have been proposed, chemical absorption and adsorption are currently believed to be the most suitable ones for post-combustion power plants. The operation of the chemical absorption process is reviewed in this work, together with the use of absorbents, such as the ionic liquid, alkanolamines and their blended aqueous solutions. The major concerns for this technology, including CO2 capture efficiency, absorption rate, energy required in regeneration, and volume of absorber, are addressed. For adsorption, in addition to physical adsorbents, various mesoporous solid adsorbents impregnated with polyamines and grafted with aminosilanes are reviewed in this work. The major concerns for selection of adsorbent, including cost, adsorption rate, CO2 adsorption capacity, and thermal stability, are compared and discussed. More effective and less energy-consuming regeneration techniques for CO2-loaded adsorbents are also proposed. Future works for both absorption and adsorption are suggested.

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A Review of CO2 Capture by Absorption and Adsorption

Alkanolamine solutions are frequently used as solvent for the removal of acid compounds from industrial gases (Kohl and Riesenfeld, 1979). Depending on the process requirements, e.g., selective removal of H2S, CO2-bulk removal, several options for alkanolamine based treating solvents with varying compositions of the solution have been proposed. In this paper an overview is presented of the mechanisms that have been proposed in literature and the kinetic data for the various reactions are critically evaluated. Conclusions on the applicability and restrictions are discussed along with perspectives. In addition white spots in the present knowledge are indicated. The reaction between CO2 and primary/secondary amines both in aqueous and non-aqueous solutions can be described over a wide range of conditions and amine concentrations with the zwitterion-mechanism as originally proposed by Caplow (1968) and reintroduced by Danckwerts (1979). All published results, both non-aqueous and aqueous solutions, amine-prom...

On the kinetics between co2 and alkanolamines both in aqueous and non-aqueous solutions. an overview

Recent progress and new developments in post-combustion carbon-capture technology with amine based solvents

Conventional MCM-41 and pore-expanded MCM-41 (PE-MCM-41) silicas have been used as supports for grafting 3-[2-(2-aminoethylamino)ethylamino]propyl trimethoxysilane (TRI) and tested for CO2 adsorption. The effects of the quantity of triamine silane added to the grafting mixture on the CO2 adsorption capacity and apparent adsorption rate have been examined. The results showed that when both supports were grafted under the same conditions, PE-MCM-41 was grafted with slightly larger quantities of amine than MCM-41, for all controlled silane additions. Based on the adsorption performance of the materials using a dry 5% CO2/N2 feed mixture, the optimal quantity of triamine silane added to the grafting mixture was determined to be ca. 3.0 cm3/g(SiO2), for both MCM-41 and PE-MCM-41. The CO2 adsorption capacity of TRI−PE-MCM-41 was significantly higher than that of TRI−MCM-41. Furthermore, the dynamic adsorption performance of TRI−PE-MCM-41 was far superior to TRI−MCM-41. In comparison to 13X zeolite, TRI−PE-MCM-4...

Applications of Pore-Expanded Mesoporous Silicas. 3. Triamine Silane Grafting for Enhanced CO2 Adsorption

The reaction of CO2 with TEA, DMMEA, and DEMEA has been studied at 293, 303, 318 and 333 K. All the kinetic experiments were carried out in a stirred cell reactor operated with a flat, smooth and horizontal gas-liquid interface. A numerical method, which describes mass transfer accompanied by reversible chemical reactions, has been applied to infer rate constants from the experimental data. It is argued that the contribution of the CO2 reaction with OH- to the observed reaction rate may have been overstimated in most literature on tertiary amine kinetics as serious depletion of OH- toward the gas-liquid interface usually occurs. 
For all the amines studied, the reaction order in amine was found to be about one for each temperature investigated. This is in good agreement with the base catalysis mechanism proposed by Donaldson and Nguyen (1980). All kinetic data could be summarized reasonably well in one Bronsted relationship.

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Kinetics of Carbon Dioxide with tertiary Amines in aqueous solution

https://ris.utwente.nl/ws/files/6649964/Littel92kinetics2.pdf

Kinetics of CO2 with primary and secondary amines in aqueous solutions—II. Influence of temperature on zwitterion formation and deprotonation rates

https://ris.utwente.nl/ws/files/6860697/Littel92kinetics1.pdf

Kinetics of CO2 with primary and secondary amines in aqueous solutions—I. Zwitterion deprotonation kinetics for DEA and DIPA in aqueous blends of alkanolamines

https://ris.utwente.nl/ws/files/6773873/Littel91physical.pdf

Physical absorption into non-aqueous solutions in a stirred cell reactor

Absorption data for COS and N,O in aqueous solutlons of N-methyldiethanolamine (MDEA), ethylene glycol, and sulfolane (tetrahydrothiophene 1,l-dioxide) at 298 K and solubility data for COS in water at temperatures ranging from 298 to 338 K are presented. Also density, viscosity, N,O solubility, and N,O dlffusivity data are reported for a wide range of aqueous aikanolamine solutions, aqueous mlxtures of alkanoiamines, and solutions of MDEA in water/ethanol. It is shown that an analogy between COS and N,O with respect to gas solubility in aqueous solutions of ethylene glycol and sulfolane holds up to about 25 mass %. This seems to justify, for engineering purposes, the application of this analogy for the estimation of COS solubilitles in diluted aqueous amine solutions. Direct
verificatlon of a COS-N,O analogy was provided by absorption of N,O and COS into aqueous MDEA solutions in a laminar film reactor.

/pdf/solubility-and-diffusivity-data-for-the-absorption-of-cos-1dhjd1kgf3.pdf

R.J. Littel

Papers

Kinetics of Carbon Dioxide with tertiary Amines in aqueous solution

Kinetics of CO2 with primary and secondary amines in aqueous solutions—II. Influence of temperature on zwitterion formation and deprotonation rates

Kinetics of CO2 with primary and secondary amines in aqueous solutions—I. Zwitterion deprotonation kinetics for DEA and DIPA in aqueous blends of alkanolamines

Physical absorption into non-aqueous solutions in a stirred cell reactor

Solubility and Diffusivity Data for the Absorption of COS, CO2, and N2O in Amine Solutions