SLIDE 1
Oxygen Delignification
50 100 150 200
M i l l i
- n
T
- n
s
1983 1986 1994 2000 Chemical Usage of North American Bleach Plants Chlorine Total ClO2 O2 Delign.
Pulp Properties Influencing Pa & Oxygen Delignification - - PowerPoint PPT Presentation
Pulp Properties Influencing Pa & Oxygen Delignification - - PowerPoint PPT Presentation
Pulp Properties Influencing Pa & Oxygen Delignification Bleachability A.J. Ragauskas Institute of Paper Science and Technology arthur.ragauskas@ipst.edu Oxygen Delignification Chemical Usage of North American Bleach Plants 200 M i
SLIDE 2
SLIDE 3
Oxygen Delignification
- Increased interest in one and two-stage oxygen delignification
38 39 40 41 42 43 44 45 46 47 48 49 50 10 20 30 40 50 60
Pulp Yield, %.
30 ECF 30 (O) 40 (OO) 5 ( O O )
Kraft
KAPPA
D E
- p
D DEopD
Improved environmental, operating, and capital cost performance
SLIDE 4
Oxygen Delignification: Back ground
100 200 300 400 500 600 700 Citations
1 9 6 5
- 7
1 9 7
- 7
5 1 9 7 5
- 8
1 9 8
- 8
5 1 9 8 5
- 9
1 9 9
- 9
5 1 9 9 5
- 9
9
Literature
- 1960/70s
– basic engineering & chemistry
- 1980/early 90s
– process parameters, energy, environmental, pretreatments, fundamental chemistry, pulp properties
- Late 1990’s
– yield, selectivity, process parameters, lignin/carbohydrate chemistry, catalysts
SLIDE 5
O Delignification
Research Objectives
- Examine use of standard O and
aggressive O* delignification conditions on high and low kappa pulps
- High Kappa SW kraft (47)
– O: 2% NaOH, 90oC – O*: 4% NaOH, 105oC
- Low Kappa SW kraft (24)
– O: 1% NaOH, 90oC – O*: 2% NaOH, 105oC
- Effect of Peracetic Acid
Treatment
Bleach Sequences
- High Kappa SW
– O, O*, OO – PaO, PaO*, OPaO
- Low Kappa SW
– O, O*, – PaO, PaO*
- Pa: 4% Pa, pH ≈8, 70oC
SLIDE 6
O Delignification
Research Objectives-II
- Determine how varying O and
Pa-stages influences residual lignin structure and controls bleachability
Lignin Analysis Techniques
- Isolate residual lignin
- Analyze residual lignin
functional groups:
– uncondensed phenoxy – free phenoxy – acid groups – quinones – carbonyl groups--ketones
SLIDE 7
O, O*, and Pa Delignification Results
SLIDE 8
O-Delignification
High Kappa Delignification
- PaO equivalent to OO
- O* >> PaO or OO
- PaO* >> O*
- Brightness increases as %
- delign. increases*
Low Kappa Delignification
- PaO > O*
Pa treated pulps usually exhibit a higher brightness
SLIDE 9
O-Delignification: Viscosity Vs Delignification
20 20 40 40 60 60 80 80 100 100 10 10 15 15 20 20 25 25 30 30 35 35 Viscosity (cP) Viscosity (cP) Delignification (%) Delignification (%) O O OO OO PaO* PaO* PaO PaO O* O* OPaO OPaO O O O* O* PaO PaO PaO* PaO*
Low Kappa Low Kappa
High Kappa Greater delignification incurs greater loss in viscosity Higher kappa pulps yield higher post O viscosity
SLIDE 10
O-Delignification: Viscosity vs. Brightness
Higher kappa pulp yields higher brightness at a given brightness
20 30 40 50 60 10 15 20 25 30 35 Viscosity (cP) Brightness (% ISO)
O OO PaO* PaO O* OPaO O O* PaO PaO*
Low kappa
High kappa
SLIDE 11
O - Delignification: Summary
Pulp Results
- High kappa SW pulp
yield responded very well to all O treatments
- Pa improved O
performance
- >50% O
delignification is a possible target What is the Chemistry? Color Bodies Reactive Sites
O O O O OCH3
OH OCH3 OH OCH3 OH H3CO
SLIDE 12
Fate of Quinones and Carbonyl Groups After O, O*, & Pa
SLIDE 13
O - Delignification: Quinones
Quinones Lignin P(OCH3)3 H2O
O P H3CO H3CO O "Quinone" Lignin 0.02 0.04 0.06 0.08 0.1 Quinone (mmol/gr lig.) B S : 4 7 O * P a O * O P a O B S : 2 4 O * P a O *
SLIDE 14
O - Delignification: Quinones
- 56
- 57
- 58
- 59
- 60
- 61
- 62
- 63ppm
IS Carbonyl Quinone
+ H2NNH CF3 O CF3 NNH
19F-NMR: Lignin
SLIDE 15
O - Delignification: Quinones
0.0 0.1 0.2 0.3 0.4 0.5 0.6 B S ( 4 7 ) O O * P a O P a O * O O O P a O D Quinone (mmol/g Lignin)
P31 F19
Minor increase in quinones and virtually no increase in carbonyl content of residual lignin
SLIDE 16
O - Delignification: Phenoxy Groups
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 PhOH mmol/gr Lign. B S : 4 7 O : 2 7 P a O : 1 9 O P a O : 1 9 O * 1 4 P a O * 1 O O : 1
- Uncond. Phenoxy
Condensed Phenoxy
OH OCH3
Reactive
OH OCH3 OH H3CO
Unreactive
SLIDE 17
O - Delignification: Acid Groups
0.5 1 1.5 2 2.5 3 PhOH mmol/gr Lign.
BS:47 O:27 PaO:19 OPaO:19 O*14 PaO*10 OO:10 BS:24 O:14 O*:8 PaO*7
Generally
- Acid groups ∝
% delign.
- Pa introduces
more acid groups
Note: despite increased lignin ‘solubility’ resistant to extraction
SLIDE 18
O - Delignification: β-O-Aryl Ether Groups
0.08 0.1 0.12 0.14 0.16 0.18 0.2 0.22 PhOH mmol/gr Lign.
BS:47 O:27 PaO:19 OPaO:19 O*14 PaO*10 OO:10 BS:24 O:14 O*:8 PaO*7
Note: PhOMe does not change
O OMe OH O HO OMe
Important linkage in pulping & D Not in O
SLIDE 19
O - Delignification: Residual Lignin Results
- Primary site of
- xidation is
unsubstituted phenolics
- Substituted phenols
resistant to oxidation
- Quinones/carbonyls
appear not to accumulate during O
- Lignin structure
enriched in acid groups
- PhOMe and β-O-Aryl
Ether unreactive
SLIDE 20
O - Delignification: Implications
- Enhanced O-stages
must activate both condensed and unsubstituted PhOHs
- Mass transfer
- Lignin model
compounds provided limited practical guidance
SLIDE 21