Mohammad Reza Eghlimpour (Petroleum University of Technology)

Reza Mosayebi Behbahani

Makan Yousefi

Maede Zargar

Keywords: Amine-based, gas sweetening, Methyldiethanolamine (MDEA), Ionic Liquid,Bmim[Ac]

Results & Discussion

CO2 & CH4 solubility in aqueous mixtures of [Bmim][Ac] &MDEA (in mass fraction

(wt%)) at T=308.15 K and pressures up to 50 bar.

Solubility of CO2 & CH4 in mixture CH4/CO2 (75/25 % mole) in aqueous mixtures of

[Bmim][Ac] +MDEA (in mass fraction (wt%)) at T=308.15 K and pressures up to 50 bar.

Solubility of CO2&CH4 in mixture CH4/CO2 (50/50 % mole) in aqueous mixtures of[Bmim][Ac] +MDEA (in mass fraction (wt%)) at T=308.15 K and pressures up to 50 bar.

Solubility of CO2&CH4 in mixture CH4/CO2 (25/75 % mole) in aqueous mixtures of[Bmim][Ac] +MDEA (in mass fraction (wt%)) at T=308.15 K and pressures up to 50 bar.

References:[1]Afshin Ahmady, Mohd Ali Hashim, and Mohamed Kheireddine Aroua, Experimental

Investigation on the Solubility and Initial Rate of Absorption of CO2 in Aqueous Mixtures of

Methyldiethanolamine with the Ionic Liquid 1-Butyl-3-methylimidazolium Tetrafluoroborate

, Chemical Engineering Department, University of Malaya, 50603 Kuala Lumpur, Malaysia.

[2]Abolfazl Shojaeian, Ali Haghtalab. Solubility and density of carbon dioxide in different

aqueous alkanolamine solutions blended with 1-butyl-3-methylimidazolium acetate ionic

liquid at high pressure. Department of Chemical Engineering, Tarbiat Modares University,

P.O. Box: 14115-143, Tehran, Iran .

Abstract:Carbon dioxide has been identified as the main factor responsible for

global warming. Currently, the process applied for CO2 capture at a

large scale is the amine-based solvent absorption process. Amines,

considered as conventional solvents, are being used for gas sweetening

process. The main disadvantages of these conventional amines are

solvent degradation, high volatility, corrosion and high energy cost of

their regeneration causing low solvent recovery and high energy

consumption in the regeneration process because of the large enthalpy of

formation produced in reactions with CO2. Ionic liquids, known as

“green solvents”, are considerably given attention as promising

alternatives for amines to remove acid gases in gas sweetening process.

Ionic liquids have several remarkable advantages such as low vapor

pressure, low cost of regeneration, nonflammability, high thermal and

chemical stability. The main aim of this thesis was to experimental

investigation on the Solubility and Absorption of CO2 and CH4 in

Aqueous Mixtures of Methyldiethanolamine (MDEA) with the Ionic

Liquid 1-butyl-3-methylimidazolium acetate ([Bmim][Ac]. The

solubility of CO2, CH4, and CO2/CH4 mixtures (25/75 mol%, 50/50

mol% and 75/25 mol%) in Aqueous Mixtures of ionic liquids

[Bmim][Ac], and MDEA are measured at 308.15 K for pressures up to

50 bar.

Introduction:Absorption is one of the most effective methods to remove carbon

dioxide (CO2) and hydrogen sulfide (H2S), namely acid gases, from

natural gas. Amines, considered as conventional solvents, are being used

for gas sweetening. Alkanolamines including diethanolamine (DEA),

monoethanolamine (MEA), and methyl-diethanolamine (MDEA) are

being utilized for CO2 capture. In this research, a new aqueous solution

of ILs with Amins is examined for absorbing CO2 form CH4 by the

combination of physical and chemical absorption. The studied ILs were

1-butyl-3-methylimidazolium acetate ([Bmim][Ac]) and Amin is MDEA.

Volumetric diagram of the apparatus.

.

Conclusion:It had been found that adding amino acid IL greatly reinforced the

CO2 absorption of MDEA aqueous solution at high pressure. For feed

gas CO2/CH4=75/25 &50/50 mol% aqueous mixtures of 35 wt%

MDEA+ 5 wt% [Bmim][Ac] had higher capacity to absorbed CO2 and

For feed gas CO2/CH4= 25/75 mol% 30 wt% MDEA+ 10 wt%

[Bmim][Ac] led to higher values of CO2 solubility at medium and high

pressures. Aqueous mixture of [Bmim][Ac]+MDEA had higher capacity

to absorb CO2 at high pressure because of the physical absorption CO2

gas by ionic liquid ([Bmim][Ac])in liquid phase. On other hand at low

pressure MDEA led to chemical absorption of CO2 therefore had higher

capacity to absorb CO2. CH4 solubility in mixture has been decreased

approximately by adding [Bmim][Ac] to the aqueous mixture of MDEA.

0

5

10

15

20

25

30

35

40

45

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Pre

ssure

(b

ar)

Mole fraction CO2

CO2+40w%MDEA

CO2+35w%MDEA+5%[Bmim][Ac]

CO2+30w%MDEA+10w%[Bmim][Ac]

0

5

10

15

20

25

30

35

0 0.005 0.01 0.015 0.02

Pre

ssure

(b

ar)

Mole fraction CH4

CH4+40w%MDEA

CH4+35w%MDEA+5w%[Bmim][Ac]

CH4+30w%MDEA+10w%[Bmim][Ac]