CO2 Capture Using Deep Eutectic Solvents

Prof.  Emadadeen  M.  AliKing Saud University, Saudi Arabia

Global Worming

Fossil fuels (coal, oil, natural gas)

Carbon Dioxide (CO2)

Global Warming

Sources of CO2 emissions

World-wide statistical data of CO2

CO2 separation processSeparation using Sorbent/Solvent

Solvent Characteristics

Preparation and material Cost

Environmental impact

Capacity

MEAAdvantage & Disadvantages

Advantages

Inexpensive material (1ton of MEA cost $1100)

DisadvantagesLow carbon dioxide loading capacity

Equipment corrosion

High-energy penalty during absorbent regeneration

MEA: Monoethanolamin is the most common material used in industry to absorb CO2

Ionic Liquids

A new class of compounds that have emerged in the last twenty years with several applications in chemical and physical separation.

ILs are environmentally-friendly alternatives to organic solvent for liquid/liquid extraction, and separation.

ILs face a challenge in large-scale industrial applications, due to complicated synthetic processes and the expensive raw material chemicals

Deep Eutectic Solvents

deep eutectic solvents (DESs) have been recognized as a cost effective alternative to ILs

DESs possess several advantages over traditional ILs., they can be prepared easily in high purity at low cost.

In addition, they are non-toxic, have no reactivity with water and most importantly being biodegradable

Objectives

1. Prepare different types of DES

2. Test the solubility of CO2 in these DES

3. Model the CO2 solubility using

Peng-Robinson EoS

EC 400 Variable volume high pressure equilibrium cell

(SEPAREX, France).

Experiment Protocol

The visual cell is cleaned, evacuated using vacuum pump, and kept at fixed temperature using a circulating water bath.

A pre-determined amount of DES is introduced to the cell using the HPLC pump. CO2 is then introduced to the cell at a certain pressure.

The mixture is stirred using the magnetic bar until equilibrium is achieved.

The change in the volume of cell is recorded. The mass of dissolved CO2 is calculated using Benedict-Webb-Robin equation of state

Solubility Modeling

Peng Robinson Equation of State

Subject to:

)()( bvbbvv

a

bv

RTP

2,, 2

min sCOkyx

xxijii

nciff Vi

Li ,,1,ˆˆ

nc

i

nc

iii yx

1 1

1,1

)()( bvbbvv

a

bv

RTP

Solubility and physical properties of DES at T=25 oC, P=125 psi

Code Components Ratio x Tc, K Pc, bar

D01 Bc Glycerol 1 12 0.0511 749.0 34.1 1.4

D02 Bb Ethylene Glycol 1 12 0.0503 632.3 46.5 1.0

D03 Mb Ethanol Amine 1 6 0.1441 654.1 44.0 0.7

D04 Mb Ethanol Amine 1 7 0.1254 646.0 45.1 0.7

D05 Mb Ethanol Amine 1 8 0.1189 639.8 46.1 0.7

D06 CC Ethanol Amine 1 6 0.1096 594.1 48.9 0.7

D07 CC Di Ethanol Amine 1 6 0.0925 693.4 29.7 1.1

D08 TAB Ethanol Amine 1 6 0.1168 613.8 39.2 0.7

D09 TAB Di Ethanol Amine 1 6 0.1036 717.7 25.5 1.1

D10 TAB Tri Ethanol Amine 1 3 0.0830 795.7 19.3 1.4

BC: Benzyltryphenilphosphonium chloride, BB:n-Butyltriphenylphosphonium bromide, MB: Methyltriphenylphosphonium bromide, TAB: Tetra Butyl Ammonium Bromide

Solubility and physical properties of CC-salt /des at

T=25 oC

Code Components RatioPressure

(bar) x Tc, K Pc, bar

I2 CC TG 1 4 1.38 0.0003 718.9 27.4 1.04

I2 CC TG 1 4 5.12 0.0021 718.9 27.4 1.04

I2 CC TG 1 4 8.61 0.0028 718.9 27.4 1.04

I2 CC TG 1 4 13.80 0.0101 718.9 27.4 1.04

CC: Choline Chloride, TG: Triethylene Glycol

Comparison of CO2 solubility in DESs, ♦: experimental; ▲: model; □:

corrected model

: CO2 solubility in CC-based DEs with pressure, ♦: experimental; ▲: model with

fixed k; □: model with variable k

Conclusions

The solubility of CO2 in ethylene glycol and glycerol based DESs is much smaller than that in MEA aqueous solution

The solubility depended on the type of salt used and on the salt:HBD molar ratio.

The modeling results indicated the necessity to adjust the interaction parameter in order to improve the ability of the PR EoS to predict the CO2 solubility

Thank you