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Study on Reaction yMechanisms of Amine Absorbent and AldehydesAbsorbent and AldehydesTOSHIBA Corporation,Corporate Research and Development Center
Asato Kondo, Satoshi Saito, Hiroko Watando, Takashi Kuboki
Regina 8th Sept 2015
© 2015 Toshiba Corporation
Regina, 8 Sept. 2015
Outline
• Introduction• Experimental Quantitative analysis of aldehydes Qualitative analysis of reaction products
• Results and Discussions Reaction mechanism of amines and aldehydes
• Primary amine• Secondary amines• Tertiary amines
• Summary
© 2015 Toshiba Corporation 2Study on reaction mechanisms of amine absorbent and aldehydes
Outline
• Introduction• Experimental Quantitative analysis of aldehydes Qualitative analysis of reaction products
• Results and Discussions Reaction mechanism of amines and aldehydes
• Primary amine• Secondary amines• Tertiary amines
• Summary
© 2015 Toshiba Corporation 3Study on reaction mechanisms of amine absorbent and aldehydes
Background of this Study
Process flow diagram for CO2 capture
PURIFIED CO2TREATED FLUE GAS
CO absorbent:
RBE
R
PER
CO2 absorbent:Amine aqueous solution
BS
OR
STR
IPP
Degradation products of aminesammonia A Sammonia, organic acids, aldehydes, etc.
FLUE GAS
© 2015 Toshiba Corporation 4Study on reaction mechanisms of amine absorbent and aldehydes
Background of this Study
Amine
Less in absorbentN l
degradation
Not easy to analyze
Aldehyde
IncreaseFig Inc ease in concent ation of o ganicoxidization
IncreaseFig. Increase in concentration of organic acid in absorbent during operation Ref. S. Saito, Energy Procedia, 51, 176( 2014 )
Organic Acid
In this study, we describe specific reaction mechanisms of amines and aldehydes.
© 2015 Toshiba Corporation 5Study on reaction mechanisms of amine absorbent and aldehydes
Research on the reactivity of amines and aldehydes
Amine Function Abbreviation Amine compoundPrimary amine MEA Monoethanol amine
Table Amines used in this study
Primary amine MEA Monoethanol amine
Secondary amines
DEA Diethanol amineMAE Methyl amino ethanolSecondary amines et y a o et a oPZ Piperazine
TEA Triethanol amine
Tertiary amines DMAE Dimethyl amino ethanolMDEA Methyl diethanol amine
0.2 g/L and 10 g/L acetaldehyde solution in amine aqueous solution
acetaldehyde
solution in amine aqueous solution was prepared.
50 g/L amine aqueous solution
© 2015 Toshiba Corporation 6Study on reaction mechanisms of amine absorbent and aldehydes
Outline
• Introduction• Experimental Quantitative analysis of aldehydes Qualitative analysis of reaction products
• Results and Discussions Reaction mechanism of amines and aldehydes
• Primary amine• Secondary amines• Tertiary amines
• Summary
© 2015 Toshiba Corporation 7Study on reaction mechanisms of amine absorbent and aldehydes
Quantitative analysis method for acetaldehyde derivatized by PFBOA
Aldehydes were derivatized by O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine (PFBOA), and the derivatives were extracted with n-hexane before determination by GC/MS as aldoximes.
Derivatization of acetaldehyde using PFBOA
y /
F F
ONH2
CH3 OF F
ON CH3
+F
F
F
C3 O
FF
F
PFBOA acetaldehydePFBOA acetaldehyde
+
PFBOA-acetaldehyde PFBOA-acetaldehyde
*PFBOA-acetaldehyde shows two peaks due to geometric isomer
© 2015 Toshiba Corporation 8
peaks due to geometric isomer.
Study on reaction mechanisms of amine absorbent and aldehydes
Recovery amount of aldehydes in MEA aqueous solutionT bl R t f ld h d i MEA
Sample Addition amount of aldehyde
Reaction time *1ofamine and aldehyde
DerivatizationpH
Recovery of acetaldehyde(%)
Table Recovery amount of aldehyde in MEA
Water 0.2 g/L - *2 10010 min Weak-acid 10610 i W k b i 60
MEA(50g/L)
0.2 g/L10 min Weak-basic 607 days Weak-acid 1027 days Weak-basic 68( g/ ) 7 days Weak basic 68
10 g/L10 min Weak-acid 953 days Weak-acid 54
*1 The time period between addition of aldehyde and analysis of recovery amount of aldehyde in amine aqueous solution.
*2 W k id l Recovery amounts vary widely→ Analysis cannot be performed stably→ Investigation of reaction mechanisms
*2 Weak-acid-samples were diluted with water and H2SO4, and weak-basic-samples were diluted with only water
© 2015 Toshiba Corporation 9Study on reaction mechanisms of amine absorbent and aldehydes
gis necessary for stable analysis were diluted with only water.
Recovery amount of aldehydes in MEA aqueous solution
Addition of 0.2g/L acetaldehyde results in
Fig. Recovery amount of aldehyde in MEA
g/ y・low recovery amount of aldehyde under basic condition.・high recovery amount of aldehyde under acid condition.
© 2015 Toshiba Corporation 10Study on reaction mechanisms of amine absorbent and aldehydes
Reaction mechanisms of primary amines and aldehydes
Reactions of aldehydes and primary amines are reversible, and aldehydes are formed under acid condition, generally.
O
+-H2O
NH R1 NH
OHR
1
NR
R1
R R+
IminesHemiaminals
NH2 R
RR
R
R
AldehydesLow pH
(weak acid condition)High pH
(basic condition)
Ref. Guangtong Wang, Langmuir., 30, 1531 (2014)
・Under acid condition → Aldehydes are separated from amines.d b d ld h d d f・Under basic condition → Aldehydes and amines form imines.
All aldehydes which can be separated from amines are
© 2015 Toshiba Corporation 11Study on reaction mechanisms of amine absorbent and aldehydes
analyzed under acid condition.
Recovery amount of aldehydes in MEA aqueous solution
Fig R t f ld h d i MEAFig. Recovery amount of aldehyde in MEA
Addition of 10 g/L acetaldehyde and long reaction time results inAddition of 10 g/L acetaldehyde and long reaction time results in・low recovery amount of aldehyde even under acid condition.
© 2015 Toshiba Corporation 12Study on reaction mechanisms of amine absorbent and aldehydes
Reaction mechanisms of primary amines and aldehydes
O -H2OOHR
1
N
R1
R R+
H2O
IminesHemiaminals
NH2 R1 NH
RR
OH N
R
R
Aldehydes IminesHemiaminalsAldehydesLow pH
(weak acidic condition)High pH
(basic condition)Ref. Guangtong Wang, Langmuir., 30, 1531 (2014)
・Under acidic condition・Large amount of aldehyde Long eaction time
Low recovery amount of aldehyde・Long reaction time → Reaction of amine and aldehyde is different from the above scheme.→ Investigation of reaction products
© 2015 Toshiba Corporation 13Study on reaction mechanisms of amine absorbent and aldehydes
Outline
• Introduction• Experimental Quantitative analysis of aldehydes Qualitative analysis of reaction products
• Results and Discussions Reaction mechanism of amines and aldehydes
• Primary amine• Secondary amines• Tertiary amines
• Summary
© 2015 Toshiba Corporation 14Study on reaction mechanisms of amine absorbent and aldehydes
Compounds produced from amines and aldehydeI d i i h d f i dIn order to investigate the products from amines and acetaldehyde, we added acetaldehyde to 50 g/L amine aqueous solution and 1 g/L or 10 g/L acetaldehyde solution was prepared. They were analyzed by LC/MS and GC/MS.
acetaldehyde To investigate ionic compoundsacetaldehydeLC/MS analysis
To investigate ionic compounds
10 g/L
0〜4days later
4days later50 g/L amine aqueous solution
/ GC/MS analysisTo investigate volatile compounds
1 g/L
© 2015 Toshiba Corporation 15Study on reaction mechanisms of amine absorbent and aldehydes
Outline
• Introduction• Experimental Quantitative analysis of aldehydes Qualitative analysis of reaction products
• Results and Discussions Reaction mechanism of amines and aldehydes
• Primary amine• Secondary amines• Tertiary amines
• Summary
© 2015 Toshiba Corporation 16Study on reaction mechanisms of amine absorbent and aldehydes
LC/MS analysis of MEA reacted with acetaldehydeF d ft dditi f t ld h dFour days after addition of acetaldehyde
Mass spectrum of MEA containing acetaldehyde.
m/z 88
m/z 114 m/z 132 m/z 140
MS signals of m/z 88, 114, 132, 140/ , , ,
increased after addition of aldehyde.
I i f MEA / 88OH
NCH3
Imine from MEA:m/z 88
© 2015 Toshiba Corporation 17Study on reaction mechanisms of amine absorbent and aldehydes
Chromatogram of LC/MS
Reaction mechanisms of MEA and acetaldehydeO CH3 OH
OHNH2
O CH3
CH3OH
NH
OHーH2O
Mass number 87
OHNCH3
Mass number 87(m/z 88)
ImineUnder basic condition
Fig. m/z 88 Chromatogram of LC/MS
© 2015 Toshiba Corporation 18Study on reaction mechanisms of amine absorbent and aldehydes
Reaction mechanisms of MEA and acetaldehydeO CH3 OH
OHNH2
O CH3
CH3OH
NH
OHーH2O OH
NCH3
Mass number 87ass u be 8(m/z 88)
ImineUnder basic condition
OHNHCH2
Mass number 87Mass number 87(m/z 88)
enamine
© 2015 Toshiba Corporation 19Study on reaction mechanisms of amine absorbent and aldehydes
Reaction mechanisms of MEA and two acetaldehydesO CH3 OH
OHNH2
O CH3
CH3OH
NH
OHーH2O OH
NHCH2
Mass number 87( / 88)
OH OHOHO CH
(m/z 88)enamine
OHNH
+CH2
CH3 OH
NCH2
CH2
OHNH
+CH2
CH2
O CH3 ーH2O ーH+
Mass number 113 Mass number 114Mass number 113(m/z 114)
Mass number 114(m/z 114)
h hEnamines can react with another aldehyde.The m/z 114 compound is the dienamine that MEA combined with two acetaldehydes.
© 2015 Toshiba Corporation 20Study on reaction mechanisms of amine absorbent and aldehydes
Fig. m/z 114 Chromatogram of LC/MS
Reaction mechanisms of MEA and three acetaldehydes
If another acetaldehyde reacts with MEA combined with two acetaldehydes, the m/z 140 compound is formed.
OHNCH2 OH
N+CH
CH2
OH+CH
OHCH3
O CH3 ーH2O
CH2
NCH2
CH2
NCH2
CH2 Mass number 140Mass number 114(m/z 114) (m/z 140)(m/z 114)
When the addition amount of aldehyde is large, quaternary
(ammonium(m/z 140 ;in the case of MEA) is formed.
© 2015 Toshiba Corporation 21Study on reaction mechanisms of amine absorbent and aldehydes
Fig. m/z 140 Chromatogram of LC/MS
Recovery amount of aldehydes in MEA aqueous solution
Fig. Recovery amount of aldehyde in MEAAdditi t f Addi i f
enamine Quaternary ammonium
Addition amount of aldehyde is small
Addition amount of aldehyde is large
enamine(Secondary or tertiary amine) Quaternary ammonium
I e e sible eactionR ibl ti
© 2015 Toshiba Corporation 22Study on reaction mechanisms of amine absorbent and aldehydes
Irreversible reactionReversible reaction
Outline
• Introduction• Experimental Quantitative analysis of aldehydes Qualitative analysis of reaction products
• Results and Discussions Reaction mechanism of amines and aldehydes
• Primary amine• Secondary amines• Tertiary amines
• Summary
© 2015 Toshiba Corporation 23Study on reaction mechanisms of amine absorbent and aldehydes
Recovery amount of aldehyde in DEA aqueous solutionTable Recovery amount of aldehyde in DEA
Sample Addition amount of aldehyde
Reaction time(amine and aldehyde)
DerivatizationpH
Recovery of acetaldehyde(%)
Table Recovery amount of aldehyde in DEA
Water 0.2g/L - 100
DEA
10 min Weak-acid 10010 min Weak-basic 50DEA
(50g/L) 0.2g/L10 min Weak-basic 507 days Weak-acid 637 days Weak-basic 32
When the reaction time wasWhen the reaction time was long, the recovery amount of aldehyde was low in the case f DEAof DEA.
© 2015 Toshiba Corporation 24Study on reaction mechanisms of amine absorbent and aldehydes
Fig. Recovery amount of aldehyde in DEA
LC/MS analysis of DEA reacted with acetaldehydeTh d ft dditi f t ld h d
Quaternary ammonium f DEA / 158
Mass spectrum of DEA containing acetaldehyde.
Three days after addition of acetaldehyde
m/z 158
from DEA:m/z 158
N+
CH2
m/z 132N
OHOH
CH2
The quaternary ammoniumChromatogram of LC/MS
The quaternary ammonium ion (m/z 158) were detected.The tertiary amine (m/z 132) was also detectedwas also detected, but the amount was smaller than m/z 158.
© 2015 Toshiba Corporation 25Study on reaction mechanisms of amine absorbent and aldehydes
Recovery amount of aldehyde in DEA aqueous solutionT bl R f ld h d i DEA
Sample Addition amount of aldehyde
Reaction time(amine and aldehyde)
DerivatizationpH
Recovery of acetaldehyde(%)
Table Recovery amount of aldehyde in DEA
OHCH
DEA(50g/L) 0.2g/L
7 days Weak-acid 637 days Weak-basic 32
NHOHOH N
OHOH
CH2
NOHOH
OHCH3O CH3 ーH2O
CH2CH2
O CH3 Mass number 131(m/z 132)
N+
OHOH
CH2
N+
OHOH
CH3 OH
Quaternary ammonium
2
Mass number 158(m/z 158)Since the quaternary ammonium was preferably formed, the
t f ld h d l
© 2015 Toshiba Corporation 26
recovery amount of aldehyde was low.
Study on reaction mechanisms of amine absorbent and aldehydes
Aldehyde recovery in secondary amine aqueous solution
Fig. Recovery amount of aldehyde in secondary aminesamine amount 50g/L, Addition amount of aldehyde 0.2g/L
The recovery amount of aldehyde was low in the case of the other secondary amines.
© 2015 Toshiba Corporation 27Study on reaction mechanisms of amine absorbent and aldehydes
y
Outline
• Introduction• Experimental Quantitative analysis of aldehydes Qualitative analysis of reaction products
• Results and Discussions Reaction mechanism of amines and aldehydes
• Primary amine• Secondary amines• Tertiary amines
• Summary
© 2015 Toshiba Corporation 28Study on reaction mechanisms of amine absorbent and aldehydes
Aldehyde recovery in tertiary amine aqueous solution
Fig Recovery amount of aldehyde in tertiary aminesamine amount 50g/L, Addition amount of aldehyde 0.2g/L
Fig Recovery amount of aldehyde in tertiary amines
The recovery amount of aldehyde was also low in the case of
© 2015 Toshiba Corporation 29Study on reaction mechanisms of amine absorbent and aldehydes
tertiary amines.
Reaction mechanisms of tertiary amine and acetaldehyde
Since tertiary amines reacted with aldehyde are unstable, the reverse reaction is considered superior.
+N
R2 +H+O -H2OOH
N+
R2 R
3
N+
R2 R
3
R1 N
R3
-H+RR
4
5R4 R5
R4 R5R1
NR
1N
m/z 164
Though Aldehyde recovery was low.→ Investigation of MDEA reaction products
© 2015 Toshiba Corporation 30Study on reaction mechanisms of amine absorbent and aldehydes
LC/MS analysis of MDEAChromatogram of LC/MS
After addition of acetaldehyde,
Chromatogram of LC/MS
m/z 146 increased.
m/z 146/=quaternary ammonium from MDEA
→ Even tertiary amines might react with acetaldehydes and h b f d
+CH3 CH3
quaternary ammonium might be formed.
OHN
OH
CH3
O CH3
OHN
+
OH
CH3 OH+ OH
N+
OH
CH2
-H2O
© 2015 Toshiba Corporation 31
m/z 146Study on reaction mechanisms of amine absorbent and aldehydes
Amines reacted with aldehydes
Primary amines
+aldehyde aldehyde
secondary amines
+aldehyde -aldehyde
+aldehyde -aldehyde
tertiary amines
+aldehyde aldehyde
Quaternary ammonium
+aldehyde -aldehyde
Formation of quaternary ammonium is irreversible reaction.
© 2015 Toshiba Corporation 32Study on reaction mechanisms of amine absorbent and aldehydes
For stable analysis of aldehyde in amine aqueous solution
Since amine absorbent pH is basic, aldehyde reaction with amine proceed and form imine and
O
+ Imines enamines・・・NH2 R1
proceed, and form imine and enamine.
R RImines, enamines2
Aldehydes
L H Hi h HLow pH(weak acidic condition)
High pH(basic condition)
Analysis of aldehyde amount in absorbentAnalysis of aldehyde amount in absorbent・Stored in acid condition・Quick analysis(before reaction progress)
© 2015 Toshiba Corporation 33Study on reaction mechanisms of amine absorbent and aldehydes
Summary◆In this study, the uncommon reactions between acetaldehyde and amine absorbents were described.
・Amine solution containing acetaldehyde results in enamines and imines.
・All amines, which are primary, secondary, or tertiary, could form quaternary ammonium with acetaldehyde.
◆Quantitative analysis of aldehydes in amine◆Quantitative analysis of aldehydes in amine absorbent requires care because aldehydes react with amines.amines.
© 2015 Toshiba Corporation 34Study on reaction mechanisms of amine absorbent and aldehydes
LC/MS analysis of MEA reacted with acetaldehyde (1g/L)
OHNCH3
OHN
+CH2
CH2imine
Quaternary CH2
ammonium
OHNCH2
CHWhen addition amount of ld h d 1 /L MEACH2
Dienamine(tertiary amine)
aldehyde was 1g/L, MEA formed imine and dienaminebut quaternary ammonium in one day.
© 2015 Toshiba Corporation 36Study on reaction mechanisms of amine absorbent and aldehydes
TOSHIBA Carbon Capture plant
TOSHIBA Corporation engages in CCS/CCU technology deployment.
CCU demonstration plant inSAGA, JAPAN(10〜20kg/d-CO2), g 2
CCS demonstration plant in FUKUOKA, JAPAN(10 t/d-CO2)
© 2015 Toshiba Corporation 37Study on reaction mechanisms of amine absorbent and aldehydes
*Photo from TOSHIBA websitehttp://www.toshiba.co.jp/thermalhydro/en/thermal/products/ccs/ccs.htm
What will be formed from quaternary ammonium ion?f l MEA
CH2
Quaternary ammonium ion
2 hydroxyTo other compounds
OHNH2
for example; MEA
OHN
+CH2
CH
2-hydroxy-ethyl
compounds
+ three acetaldehydesCH2
Double bond・Polymerization? NCH2
CH2
Substituent group・transferring
Reference
Polymerization?→foaming?
・Oxidation?CH2
・transferring
+CH3OH
Y. Hayashi, J. Jpn. Oil. Chem. Soc. ,Vol.36, No.6, 409(1987)
X- KOHCH3 The Ethanol group is selectively eliminated
ON
+
R OH 120℃N
R OHfrom dihydroxyethyl ammonium salt under basic condition.
O+
There is possibility that quaternary ammonium from amines and
© 2015 Toshiba Corporation 38Study on reaction mechanisms of amine absorbent and aldehydes
p y q yaldehydes forms many deteriorating products.
Formaldehyde reaction with amine
Sample Addition amount of aldehyde
Reaction time(amine and aldehyde)
DerivatizationpH
Recovery of acetaldehyde(%)
Water 0.2g/L - 100
MEA
10 min Weak-acid 9510 min Weak basic 98MEA
(50g/L)
0 2 /L
10 min Weak-basic 984 days Weak-acid 974 days Weak-basic 101
0.2g/Ly
DEA
10 min Weak-acid 9410 min Weak-basic 101
(50g/L) 4 days Weak-acid 1054 days Weak-basic 105
Recovery amount of formaldehyde is 100% in any cases
© 2015 Toshiba Corporation 39Study on reaction mechanisms of amine absorbent and aldehydes
Reaction mechanisms of amine and formaldehyde
MEA and formaldehyde
Secondary amine and formaldehyde
Reversible reaction
© 2015 Toshiba Corporation 40Study on reaction mechanisms of amine absorbent and aldehydes
Amine reactAmine CO2
degradation
Amine-CO2CO2
Aldehyde SOxNOx
degradationNOxmetal
Organic acid ・・・
© 2015 Toshiba Corporation 41Study on reaction mechanisms of amine absorbent and aldehydes
Aldehyde recovery in secondary amine aqueous solutionTable Recovery amount of aldehyde in secondary amines
Sample Addition amount of aldehyde
Reaction time(amine and aldehyde)
DerivatizationpH
Recovery of acetaldehyde(%)
Table Recovery amount of aldehyde in secondary amines
Water 0.2g/L - 100
DEA
10 min Weak-acid 10010 min Weak-basic 50DEA
(50g/L)10 min Weak-basic 507 days Weak-acid 637 days Weak-basic 32
0.2g/L
y
PZ(50 /L)
10 min Weak-acid 10410 min Weak-basic 86
(50g/L) 7 days Weak-acid 457 days Weak-basic 33
MAE 10 min Weak acid 98MAE(50g/L)
10 min Weak-acid 9810 min Weak-basic 47
© 2015 Toshiba Corporation 42Study on reaction mechanisms of amine absorbent and aldehydes
Aldehyde recovery in tertiary amine aqueous solutionTable Recovery amount of aldehyde in tertiary amines
Sample Addition amount of aldehyde
Reaction time(amine and aldehyde)
DerivatizationpH
Recovery of acetaldehyde(%)
Table Recovery amount of aldehyde in tertiary amines
Water 0.2g/L - 100
TEA
10 min Weak-acid 10110 min Weak basic 52TEA
(50g/L)10 min Weak-basic 527 days Weak-acid 607 days Weak-basic 39
0.2g/L
y
DMAE(50g/L)
10 min Weak-acid 9510 min Weak-basic 47
MDEA(50g/L)
10 min Weak-acid 10110 min Weak-basic 437 days Weak acid 47(50g/L) 7 days Weak-acid 477 days Weak-basic 20
© 2015 Toshiba Corporation 43Study on reaction mechanisms of amine absorbent and aldehydes