Finding The Sweet Spot for. Oxygen Delignification

Transcription

1 Finding The Sweet Spot for Oxygen Delignification Yunqiao Pu, Rallming Yang, Lucian Lucia, Art Ragauskas Institute of Paper Science and Technology Hasan Jameel - North Carolina State University

2 Sweet Spot The place on a bat, club, or racket where it is most effective to hit a ball $$$$$$$$$$$$$$$$ We conclude that the sweet spot--or, in scientific terms, the centre of percussion of a uniform baseball bat lies two-thirds of the way down the bat from the batter's end.,,,

3 Finding The Sweet Spot for Oxygen Delignification Where is O or OO Sweet Spot? Chemical Usage of North American Bleach Plants Chlorine Chlorine Dioxide O Delign. Driven largely by environmental issues

4 Finding The Sweet Spot for Oxygen Delignification Yield on Wood, % (OO)DED 30DEDED 30ODED 50(OO) Pulping Kappa Number O Sweet Spot: Identifying pulping conditions that optimize O and OO performance to - Enhanced yield - Improved bleachability - Improved selectivity - Improved physical pulp properties

5 Delignification Pulping Conditions Low AA Med. AA High AA Active Alkali H-Factor* Kappa # Viscosity/cP Yield *25% sulfidity

6 Delignification O and OO Delignification Conditions: Pulp: Low AA, Medium AA, High AA Temperature: o C NaOH: % O 2 : 40 psi Csc: 10% Time: 60 min.

7 Delignification: O and OO Conditions Pulp NaOH% Temp./ o C Kappa # LAA HAA Pulp Active Alkali, % Temp./ C Kappa # LAAO LAAOO LAAOO LAAOO LAAOO LAAOO LAAOO HAAO HAAOO HAAOO HAAOO HAAOO HAAOO HAAOO HAAOO HAAOO

8 Delignification O-Delignification - 1% NaOH Kappa Temperature ( C) Medium High Low HAA most bleachable LAA least

9 Delignification O-Delignification - 3% NaOH HAA most bleachable LAA least Kappa Tem perature(c) Medium High Low

10 Delignification Viscosity Selectivity - 3% NaOH VISCOSITY HAA lowest viscosity KAPPA MEDIUM HIGH LOW

11 Delignification Kappa Reduction- 100 o C HAA most bleachable LAA least Kappa NaOH % Medium High Low

12 Delignification Yield Selectivity - 3% NaOH YIELD LAA best yield HAA poorest KAPPA MEDIUM HIGH LOW

13 Delignification Models for Low AA 50 Kappa 15%AA KAPPA= *((NaOH-3)/2) *((Temp-90)/20) *((NaOH-3)/2) 2 YIELD= *((NaOH-3)/2) *((Temp-90)/2) VISCOSITY= *((NaOH-3)2) *((Temp-90)/20) *((NaOH-3)/2) 2

14 Delignification Models for High AA 50 Kappa 19%AA KAPPA= *((NaOH-3)/2) *((Temp-90)/20) *((NaOH-3)/2) 2 YIELD= *((NaOH-3)/2) *((Temp-90)/20 VISCOSITY= *((NaOH-3)/2) *((Temp-90)/20) *((NaOH-3)/2) 2 -comparable results found from MAA

15 Delignification 50 kappa for oxygen The higher alkali charge in pulping resulted in lower yield at the same kappa number 15% AA 48.5 % yield 19% AA 47.0 % yield The pulps produced with the LAA were slightly more difficult to delignify as compared to the high AA pulps The O-yield and viscosity selectivity was higher for LAA pulp with improvements of 3% yield and 6 cp in viscosity

16 Delignification Yield on Wood, % Yield Kappa Relationships (OO) 50(OO)DED 30ODED Pulping Low AA Kappa Number

17 Finding The Sweet Spot For Oxygen Delignification Fundamentals

18 Delignification: Fundamental Properties Procedure Isolate lignin from: LAA and HAA Brownstocks LAAO and HAAO, 3% NaOH kappa #30.0, 31.0, respectively LAAOO1, LAAOO2, LAAOO3, LAAOO7, LAAOO8, LAAOO9 Kappa# HAAOO1, HAAOO2, HAAOO3, HAAOO4, HAAOO6, HAAOO7, HAAOO8, HAAOO9 Kappa # Establish lignin structure using advanced NMR techniques.

19 Finding The Sweet Spot for Oxygen Delignification: HAA OCH OH mmol/gr lignin R OH OCH 3 HAA HAAO HAAOO1 C5 Condensed Phenolics C5 Noncondensed Phenolics HAAOO2 HAAOO4 HAAOO3 5,5' PhOH HAAOO6 HAAOO7 HAAOO8 HAAOO9 1.00: : : 1.15

20 Delignification: LAA mmol/gr lignin OH OCH LAA LAAO LAAOO2 LAAOO1 LAAOO3 LAAOO7 LAAOO8 LAAOO9 C5 Condensed PhOH C5 Noncondensed PhOH 5,5' PhOH R OCH 3 OH 1.00: : :1.26

21 Delignification OH mmol gr/lignin 2.00 mmol gr/lignin O HO OCH OCH OH HAA 0.00 HAAO HAAOO1 HAA HAAOO2 HAAO HAAOO4 HAAOO3 HAAOO1 HAAOO6 HAAOO2 HAAOO7 HAAOO4 HAAOO8 HAAOO9 HAAOO3 HAAOO6 Aliphatic Hydroxyl Acids HAAOO7 HAAOO8 HAAOO9 Aliphatic Hydroxyl Acids LAA similar pattern, little indication of side chain oxidation, remaining lignin only slightly oxidized

22 Delignification OH LAA, LAAO, LAAOO1 LAAOO9: 0.09 ±0.01 mmol/gr lignin HAA, HAAO, HAAOO1 HAAOO9: 0.10 ±0.01 OH O HO OCH 3 LAA LAAO, LAAOO1 LAAOO9: 3.3% ±0.1 %/C6 aromatic unit HAA, HAAO, HAAOO1 HAAOO9: 3.6% ±0.1 OH OCH 3

23 Delignification A HO OH OCH 3 UV/Vis Ionization Difference Spectroscopy LAAO LAA LAAOO7 LAAOO3 LAAOO9 LAAOO1 OH NM O OCH 3 1. λ max 250 and 300 nm are assigned to unconjugated phenolics, decreases with aggressive O-stages conditions is consistent with the 31P NMR data. 2. Lignin samples appear to be relatively free of phenolic stilbenes (λmax375 nm). 3. λ max 350 nm has been attributed to phenolic α-carbonyl groups

24 Delignification: Carbohydrates % Pulp Carbohydrate Profiles: Arabinan, Galactan, Mannan no significant variation from LAA LAOO9 & HAA HAOO9 LAA LAAO LAAOO1 LAAOO3 LAAOO7 LAAOO9 Xylan Glucan HAA HAAO HAAO1 HAAOO4 HAAOO6 HAAOO8 Xylan Glucan

25 Conclusions

26 Delignification: Conclusions The results show there is tremendous potential for improving the yield, pulp properties and oxygen bleaching performance by optimizing the pulping and oxygen bleaching together: Pulping/OO performance is predictable Modeling performance is supported by fundamental properties Bleachability vs. selectivity in competition

27 Delignification: Conclusions HAA lignin differs from LAA, latter had higher amounts of condensed phenolics (pulping control). For HAA and LAA p-hydroxylphenyl groups unreactive to O chemistry (bio control) Very little side chain oxidation of lignin bioploymer during O and OO Difference in bleachability not due to hexenuronic acid LAA and O pulps had higher amounts of xylans It is possible to find a sweet spot for O and OO

28 Acknowledgements IPST Member Companies U.S. Department of Energy