Pilot / lab scale study of CO2 separation

with ionic liquid blending

Dawei Shang, Xiangping Zhang, Suojiang Zhang

Institute of Process Engineering, Chinese Academy of Sciences

12 June-14 June, 2017

1

Global warming and CCS

Glaciers Melting www.qiankungold.com

Absorption

Membrane

PSA、TSA

CCS technologies

Chemical absorbents

Amino solutions

Physical absorbents

NHD

Ionic liquids

High gas solubility

Good thermal stability

Low heat capacity

Negligible vapor pressure

2

Molten Salts

NaCl (m.p. 800oC), LiCl-KCl (m.p. 355oC), NaCl-AlCl3 (m.p. 107oC)

Ionic Liquids

Liquid at RT

Nonvolatile

Designable

Medium / Catalyst

N N R

+

PF-

R

1

BF4-

Ionic Liquids: A New Generation of Medium

3

0.00

0.05

0.10

0.15

0.20

2005

2005

2007

2009

2012

[Bmim][PF6]

[TMG][L] [HEA][A]

[P4443][Gly]

[DAIL][Br]

Chemical absorption

(30O

C,0.1MPa)

(25O

C,0.1MPa)

(35O

C,2.24MPa)

(40O

C,1.56MPa) (40

O

C,1.31MPa)

[E1Py][Tf2N]

2014

(40O

C,1.93MPa)

Physical absorption

So

lub

ilit

y (

gC

O2/g

IL

)

Energy Environ Science, 2012, 5: 6668; J Chem Eng Data, 2010, 55: 3513; Chem Eng J, 2014, 251: 248;

Fluid Phase Equilibr, 2010, 297: 34; Ind Eng Chem Res, 2013, 52: 5835; Fluid Phase Equilibr, 2014; 365:80;

Ind Eng Chem Res, 2014, 53: 16832; RSC Adv, 2015, 5: 2470 ; Applied Energy, 2015, 154:771.

CCS with ionic liquids

4

E-17

冷却器

净化气分离器

净化气

变换气闪蒸气

闪蒸灌

半贫液泵

贫液泵 冷却器

溶液换热器

煮沸器

蒸汽

气提再生塔

再生冷却器

再生气

再生气分离灌两级解吸塔

新鲜溶剂

补充离子液体

溶剂泵

两段吸收塔

Molecular Unit operation System Cluster

Scale up of CO2 separation with ILs

Scale up for the CCS process of ILs

5

Mass transfer coefficient depends on various factors,

including viscosities and ILs’ structures

Solvents Viscosity (mPa S)

kL×105 m/s

[omim][BF4] 136.0 1.51

[bmim][BF4] 56.4 1.36

[bmim][DCA] 18.2 1.04

[bmim][NO3] 89.9 0.89

H2O 1.0 2.07

2

2 2

0

0ln

1 1

CO

L

CO CO

Pk at

P P

AIChE J, 2014, 60: 2929; Ind Eng Chem Res, 2014, 53: 428

Mass transfer of gases in ILs

6

ILs Water ILs Water

Bubble behavior in ILs and water

Different bubble behaviors in water and ILs 7

FCCS

CFD method

Models modifications

Chem Eng Sci, 2015, 135: 76

Chem Eng J, 2012, 209: 607;

Ind Eng Chem Res, 2014, 53: 428

CO2 concentration

Dynamic process of CO2 absorption

[omim][BF4] [bmim][NO3] [bmim][BF4] 95%wt[bmim][BF4]

Models of the bubble behavior

8

Process simulation and cost estimation

Experimental and calculated heat capacities of ILs Effect of αlean on the regeneration thermal energy

requirement of MEA and IL-based processes

Ind. Eng. Chem. Res. 2014, 53: 11805−11817

Modified process flow diagram for CO2 capture with

ILs-amine blending

[Bpy][BF4]- MEA process can save

about 15% regeneration heat duty

compared to the conventional MEA

process.

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CO2 separation from syngas

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Continuous apparatus for CO2 capture

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CO2 N2

Absorption

tower

Rich

solvents

Lean

solvents

CO2 detector

Desorption

tower

Continuous apparatus for CO2 capture

12

Solvent

27% MDEA

3% PZ

(10% Ionic liquid)

Pressure ~ 10 Bar

Gas flow CO2 – 200 L/h

N2 - 300 L/h

Fluid flow 2~5 L/h

Parameters and part results

Component of the absorbent and the operating parameters

Amine solution

Pressure (Bar) 10.3 10.4

Liquid-gas ratio (L/h) 3.5/500 3.5/500

Average removal rate (%) 93.4 94.1

Time (h) 53.38 21.38

Regeneration energy

(GJ/tCO2)

2.728 2.711

Outlet gas CO2 concentration and

removal rate 13

Effect of pressure on the

CO2 removal rate

Compared with amine solution, the regeneration energy of CO2 from IL-amine

blending was about 17.4% lower at the same CO2 removal rate and the same

parameters of the absorption tower.

IL-amine blending for CO2 capture

/℃

Effect of temperature on

the CO2 removal rate

Effect of liquid-gas ratio on

the CO2 removal rate

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CO2 separation from landfill gas

15

CO2 removal from landfill gas with IL blending

10m3 / h of gas flow

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CO2 removal from landfill gas with IL blending

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Solvent 90% NHD

10% Ionic liquid

Pressure ~ 7 Bar

Gas flow ~1000 L/h

(CO2~33%, CH4~40%)

Fluid flow 420 L/h

Component of the absorbent and the operating parameters

The adding of IL slightly decreased

the CO2 solubility but increased the

selectivity of CO2 / CH4.

CO2 removal from landfill gas with IL blending

18

CO2 separation from melamine

industry tail gas

19

CO2 / NH3 separation with water

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CO2 / NH3 separation with ILs

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Types ILs Initial pH* pKa

Conventional IL [Bmim][NTf2] 7.13 -

Protic IL [Bim][NTf2] 5.14 6.79

Brønsted acidic IL [HOOC(CH2)3mim][NTf2] 3.52 4.61

Designing of the ILs

Structures of (a) [Bmim][NTf2], (b) [Bim][NTf2] and (c)

[HOOC(CH2)3mim][NTf2]

* pH and pKa of ILs were measured in water and DMSO solution

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Vapor-liquid equilibrium measurement apparatus: a, NH3; b1, b3-5, ball valve; b2, regulating valve; c1, c2,

pressure sensor; d, gas reservoir; e, absorption vessel; f, magnetic stirrer; g, vacuum pump; h, water bath

( )

( )( )

RT a Tp

V b V b V b

Measuring apparatus and EOS

Equation of state:

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Protic IL for NH3 separation

Solubility of NH3 in ILs at 313K

2.69 mol NH3/ mol IL

1.54 mol NH3/ mol IL

0.28 mol NH3/ mol IL

NH3 solubility in protic IL was about 1.7 times than carboxyl-functionalized

IL and 10 times than conventional IL. 24

In-situ FTIR

NMR

Quantum

chemistry

calculation

Schematic for the possible mechanism

of absorption of NH3 by [Bim][NTf2]

Green Chem. 2017, 19, 937-945

Possible absorption mechanism

25

NH3 tail gas treatment apparatus

Apparatus for 800M Nm3/a gas treatment 26

Acknowledgements

These studies were financially supported by the National

Natural Science Fund for Distinguished Young Scholars

(21425625) and the CLIMIT program and the Research

Council of Norway (215732).

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