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 150 T l o l 100 n i s o 50 n 0 1983 1986 1994 2000 Chlorine Total ClO2 O2 Delign. Improved environmental and operating cost performance

Oxygen Delignification • Increased interest in one and two-stage oxygen delignification 50 49 ) O O ( 48 0 5 Pulp Yield, %. 47 40 (OO) D p o E 46 D Kraft 45 DEopD 30 (O) 44 43 42 30 ECF 41 40 39 38 0 10 20 30 40 50 60 KAPPA Improved environmental, operating, and capital cost performance

Oxygen Delignification: Back ground Literature 700 • 1960/70s 600 Citations – basic engineering & chemistry 500 • 1980/early 90s 400 – process parameters, energy, 300 environmental, pretreatments, 200 fundamental chemistry, pulp 100 properties 0 • Late 1990’s 0 5 0 5 0 5 9 7 7 8 8 9 9 9 - - - - - - - 5 0 5 0 5 0 5 – yield, selectivity, process 6 7 7 8 8 9 9 9 9 9 9 9 9 9 1 1 1 1 1 1 1 parameters, lignin/carbohydrate chemistry, catalysts

O Delignification Research Objectives Bleach Sequences • Examine use of standard O and aggressive O* delignification • High Kappa SW conditions on high and low – O, O*, OO kappa pulps – PaO, PaO*, OPaO • High Kappa SW kraft (47) – O: 2% NaOH, 90 o C • Low Kappa SW – O*: 4% NaOH, 105 o C – O, O*, • Low Kappa SW kraft (24) – PaO, PaO* – O: 1% NaOH, 90 o C – O*: 2% NaOH, 105 o C • Pa: 4% Pa, pH ≈ 8, 70 o C • Effect of Peracetic Acid Treatment

O Delignification Lignin Analysis Techniques Research Objectives-II • Determine how varying O and Pa-stages influences residual • Isolate residual lignin lignin structure and controls • Analyze residual lignin bleachability functional groups: – uncondensed phenoxy – free phenoxy – acid groups – quinones – carbonyl groups--ketones

Delignification Results O, O*, and Pa

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

O-Delignification: Viscosity Vs Delignification Delignification (%) Delignification (%) 100 100 PaO* OPaO PaO* OPaO PaO* PaO* 80 Greater 80 O* O* delignification O* 60 O* 60 incurs greater PaO PaO PaO PaO loss in viscosity 40 40 OO OO O O O O Higher kappa 20 20 pulps yield High Kappa Low Kappa Low Kappa higher post O 0 0 viscosity 10 15 20 25 30 35 10 15 20 25 30 35 Viscosity (cP) Viscosity (cP)

O-Delignification: Viscosity vs. Brightness Brightness (% ISO) 60 PaO* OPaO Higher kappa 50 PaO PaO* pulp yields higher 40 O* O* PaO brightness at a O given OO 30 brightness Low kappa O High kappa 20 10 15 20 25 30 35 Viscosity (cP)

O - Delignification: Summary Pulp Results What is the Chemistry? • High kappa SW pulp Color Bodies yield responded very O well to all O treatments OCH 3 O O O • Pa improved O Reactive Sites performance • >50% O delignification is a OCH 3 H 3 CO OCH 3 OH OH OH possible target

Fate of Quinones and Carbonyl Groups After O, O*, & Pa

O - Delignification: Quinones P(OCH 3 ) 3 O Quinones H 3 CO P O "Quinone" Lignin H 3 CO H 2 O Lignin 0.1 Quinone (mmol/gr lig.) 0.08 0.06 0.04 0.02 0 7 * * O 4 * * 4 O O 2 O O a : : a a S P S P P B O B

O - Delignification: Quinones 19 F-NMR: Lignin H 2 NNH CF 3 O + IS Carbonyl NNH CF 3 Quinone -56 -57 -58 -59 -60 -61 -62 -63ppm

O - Delignification: Quinones Quinone (mmol/g Lignin) 0.6 P31 0.5 F19 0.4 0.3 0.2 0.1 0.0 ) * 7 O O O O * D O 4 O a ( O a a S P P P B O Minor increase in quinones and virtually no increase in carbonyl content of residual lignin

O - Delignification: Phenoxy Groups Reactive 2 1.8 Uncond. Phenoxy PhOH mmol/gr Lign. 1.6 Condensed Phenoxy OCH 3 1.4 OH 1.2 1 Unreactive 0.8 0.6 0.4 0.2 0 H 3 CO OCH 3 7 9 9 0 0 7 4 OH OH 4 2 1 1 1 1 1 : : : : * * : S O O O O O O B a a O a P P P O

O - Delignification: Acid Groups 3 2.5 PhOH mmol/gr Lign. 2 Generally 1.5 •Acid groups ∝ 1 % delign. 0.5 •Pa introduces more acid groups 0 PaO:19 OO:10 BS:47 O:27 OPaO:19 O*14 PaO*10 BS:24 O:14 O*:8 PaO*7 Note: despite increased lignin ‘solubility’ resistant to extraction

O - Delignification: β -O-Aryl Ether Groups 0.22 Important 0.2 HO linkage in PhOH mmol/gr Lign. O 0.18 pulping & D OH OMe 0.16 Not in O OMe 0.14 O 0.12 0.1 0.08 PaO:19 OO:10 BS:47 O:27 OPaO:19 O*14 PaO*10 BS:24 O:14 O*:8 PaO*7 Note: PhOMe does not change

O - Delignification: Residual Lignin Results • Primary site of • Lignin structure oxidation is enriched in acid unsubstituted groups • PhOMe and β -O-Aryl phenolics • Substituted phenols Ether unreactive resistant to oxidation • Quinones/carbonyls appear not to accumulate during O

O - Delignification: Implications • Enhanced O-stages • Lignin model must activate both compounds provided condensed and limited practical unsubstituted PhOHs guidance • Mass transfer

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