A Novel Piperazine‐based Amine Solvent 

for Flue Gas CO2 CapturePiperazine + 4-Hydroxy-1-methylpiperidine

YANG  DU  AND  GARY  T.  ROCHELLE  PAPER  3A,  3RD  POST  COMBUSTION  CAPTURE  CONFERENCE

SEP.  2015

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Outline Background Find a blend good as Pz, but without solid precipitation

PZ/HMPD (4 Hydroxy 1 methylpiperidine) PZ/HMPD (4‐Hydroxy‐1‐methylpiperidine)

Thermal Degradation and Oxidationg

CO2 solubility, capacity,  and solid solubility

CO2 rate

Amine volatility and synthesis

Conclusions2

Conclusions

Capacity & Rate of Aminesp y

3

Capacity & Rate of Aminesp y

αlean@PCO2* 0.5kPa αrich@PCO2* 5kPa

4

Common PZ blends offer good rate & capacity

B t th l t bilitBut poor thermal stability

5

HMPD is Best of 38 AminesClass Best Cons

Imidazoles (8) NH

N

CH3

Capacity

Piperidines (8)  N

OH

Volatility2nd best

Morpholines (4)  NO

OH

Capacity

Piperazines (4) N

N Stability

Acyclic amines (14)NH

CH3

OH

O

NH

CH3

Volatility

8

CH3O CH3

N CH3OH (pKa=9.1)

Solvent EvaluationPiperazine/Hydroxy-methyl-piperidine

(PZ/HMPD)(PZ/HMPD)

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Thermal degradation at 175 °C, CO2 loadedg , 2

PZ/HMPD/1MPZ/HPD

8 10

Degradation of 2 m PZ/3 m HMPD @ 175 °CNHNHN CH3OH NH OH NNH CH3↔+ +

HMPD PZ HPD 1MPZ

NN CH3CH31,4‐DMPZ

9 11

HMPD resistant to Oxidation 70 °C, 98% O2+2% CO2, 2 2

10 14

CO2 Solubility in 2 m PZ/3 m HMPD805.E+6

158 C

70

75

5 E+4

5.E+5

e (Pa)

100 C (WWC)96 C

65

70

5.E+3

5.E+4

kj/m

ol)

pressure

40 C

20 C

Habs@1500 Pa is 68.5 kJ/mol

60

65

5.E+2

5.E+3

H abs(k

partial p

20 C

555.E+1CO2p

Open points: high P VLE

505.E+00 5 1 1 5 2 2 5 3

Solid points: WWCLines: semi‐empirical equation

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0.5 1 1.5 2 2.5 3

CO2 (mol/kg H2O+Amine)

CO2 Capacity in 2 m PZ/3 m HMPD

25600 40 C

6400

12800

e (Pa)

1600

3200

pressure

400

800

1600

partial p

Capacity = 1.9 – 1.3 

200

400

CO2p

Open points: high P VLE

p y= 0.6 mol CO2 kg 

50

100

0 5 1 1 5 2 2 5 3

Solid points: WWCLines: semi‐empirical equation

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0.5 1 1.5 2 2.5 3

CO2 (mol/kg H2O+Amine)

2 m PZ/3 m HMPD Solid Solubilitygood to 4oC

Solution

5 m PZ/5 m HMPD

5 m PZPZ 6H O ( )PZ.6H2O (s)

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CO2 Absorption Rate in 2 m PZ/3 m HMPD by WWC

2 m PZ/3 m HMPD @40 C20

s) 80

6020

2.E‐6

/Pa m

2 s 80

5 m PZ @40 C

g' (m

ol/ 100

k g

2.E‐7100 1000 10000

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PCO2* 40C (Pa)

Capacity & Rate of Amines

(μ=4.2 cP)

(μ=5 cP)

(μ=18 cP)

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Volatility of PZ/HMPD, CO2 loaded

6.4 5 m PZ/2.3 m AMP

3.2 7 m MEA5 m PZ/5 m HMPD 

1.6Pa)

2 m PZ/3 m HMPD 

0.8P am(P

8 PZ

0.4 5 m PZ/5 m MDEA

8 m PZ

0.2

5 m PZ/5 m MDEA 

50 500 5000CO2 partial pressure @40 °C 16

R

Slide 16

RGT6 make amine fonts largerRochelle, Gary T, 29/08/2015

Synthesis route to HMPD

Application: Pharmaceutical intermediate

y

Ethyl Acrylate (1)

Michael addition+2Methylaminey y y

DecarboxylationDieckmann condensation

(2) (3)

(4)

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Synthesis route to HMPDy

$(1)

Michael addition+2

$2/kg

DecarboxylationDieckmann condensation

(2) (3)

(4)

HMPD: $20/kg

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MEA: $2/kgPZ: $6/kg

Summary of amine propertiesSummary of amine properties

Amine 7 mMEA 2 m PZ/3 m HMPD 5 m PZ

kg’avg 4 4 10 1 12 1kg avg(mol/Pa m2 s * 10‐7)

4.4 10.1 12.1

Normalized  0 63 0 92 0 77Capacity (mol/kg)0.63 0.92 0.77

Tmax(C) 122 149 164max

Tmelting (C)(PCO2 = 100 Pa)

—— 4 18( CO2 00 a)Volatility (ppm)

(40 C, PCO2 = 500 Pa)30 16 5

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Texas Carbon Management Program  R h ll G M bRochelle Group Members

Yang DuYang Du yangdu@utexas.edu

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