Simultaneous detection of lignin structure, S/G ratio and carbohydrate composition from Eucalyptus hybrids by analytical pyrolysis-gc/ms

Transcription

1 Simultaneous detection of lignin structure, S/G ratio and carbohydrate composition from Eucalyptus hybrids by analytical pyrolysis-gc/ms Taina Ohra-aho, Fernando J.B. Gomes, Jorge L. Colodette, and Tarja Tamminen 6th International Colloquium on Eucalyptuys Pulp, November 24-27, 2013, Colonia del Sacramento, Uruguay

2 2 Objective The aim is to evaluate the potential of analytical pyrolysis combined with gas chromatograph mass spectrometry (Py-GC/MS) for the characterization of fiber components i.e. carbohydrates, lignin as well as S/G ratio simultaneously from Eucalyptus wood raw materials and pulps

3 3 Content Introduction to Py-GC/MS technique Raw material characterization Lignin structure S/G ratio Carbohydrate composition Characterization of pulps Carbohydrate composition Lignin composition and content

4 4 Platinum filament type pyrolyzer combined with GC/MS Pyrolysis volatilizes nonvolatile substance which then can be analyzed by GC/MS Thermal degradation Heat is used to break chemical bonds Degradation is dependent on o Sample material o Temperature Different substances (polymers) give different degradation products (profiles) Same substance pyrolyzed in identical conditions give same degradation products (profile)

5 5 Raw material characterization LIGNIN STRUCTURE, S/G RATIO AND CARBOHYDRATE COMPOSITION ANALYSIS FROM EUCALYPTUS HYBRIDS

6 6 Sample set: Eucalyptus hybrids Eighteen 7-year-old Eucalyptus hybrids, including a number of double/triple/fourth crossings among E. grandis, E. urophylla, E. globulus, E. dunnii, E. camaldulenis No Eucalyptus hybrids Short code 1 E. urophylla (IP) x E. grandis (IP) IP 2 E. urophylla (Flores IP) x E. urophylla (Timor) U1xU2 3 E. urophylla (Flores IP) x E. camaldulensis(vm2) U1xC2 4 E. urophylla (Flores IP) X [E. urophylla (R) x E. globulus (R)] U1xUGL 5 E. grandis (Coffs Harbour) x [E. urophylla (R) x E. globulus (R)] G1xUGL 6 E. dunni (R) x [E. urophylla (R) x E. globulus (R)] D1xUGL 7 E. camaldulensis (VM1) x [E. urophylla (R) x E. globulus (R)] C1xUGL 8 [E. dunnii (R) x E. grandis (R)] x [E. urophylla (R) x E. globulus (R)] DGxUGL 9 [E. dunnii (R) x E. grandis (R)] x E. urophylla (Timor) DGxU2 10 [E. dunnii (R) x E. grandis (R)] x E. camaldulensis (VM1) DGxC1 11 [E. dunnii (R) x E. grandis (R)] x E. globulus (R) (Dad, pollen) DGxGL2 12 E. dunni (KR) x E. globulus (R)(Dad, pollen) D2xGL2 13 E. grandis (Coffs Harbour) x E. globulus (R) (Dad, pollen) G1xGL2 14 E. urophylla (Timor) x E. globulus (R)(Mom, stigma) U2xGL1 15 E. urophylla (Timor) x E. camaldulensis (VM1) U2xC1 16 E. camaldulensis (VM1) x E. camaldulensis (VM1) C1xC2 17 E. dunni (R) x E. dunni (KR) D1xD2 18 VCP - E. grandis (VCP) x E. urophylla (VCP) VCP Ohra-aho, T, et al. J. Anal.Appl. Pyrolysis, 101 (2013)

7 7 Composition analysis of lignin by Py-GC/MS Pyrogram of E. urophylla (IP) x E. grandis (IP) obtained at 580 C, 2 s / / /31 31/ Peak area integration Normalization of peak areas to 100% Degradation products of lignin minutes No H units No Side chain structure, R 1 Phenol H 3 2-Methylphenol CH3 4 4-Methylphenol CH3 G units S units 2 Guaiacol 9 Syringol H 5 4-Methylguaiacol 12 Methylsyringol CH3 6 4-Ethylguaiacol 15 Ethylsyringol CH2-CH3 7 Vinylguaiacol 17 4-Vinylsyringol CH=CH2 8 Eugenol 19 4-Allylsyringol CH2-CH=CH2 10 cis-isoeugenol 22 cis-propenylsyringol CH=CH-CH3 (cis) 11 trans-isoeugenol 23 trans-propenylsyringol CH=CH-CH3 (trans) 13 Vanillin 25 Syringaldehyde CHO 16 Acetoguaiacone 28 Acetosyringone CO-CH3 20 Guaiacyl vinyl ketone 32 Syringyl vinyl ketone CO-CH=CH2 14 Homovanillin 27 Homosyringaldehyde CH2-CHO 18 Guaiacylacetone 30 Syringylacetone CH2-CO-CH (1-Hydroxyprop-2-enyl)guaiacol 33 4-(1-Hydroxy-prop-2-enyl)syringol CHOH-CH=CH2 24 Dihydroconiferyl alcohol 34 Dihydrosinapyl alcohol CH2-CH2-CH2OH 26 cis-coniferyl alcohol 35 cis-sinapyl alcohol CH=CH-CHOH 29 trans-coniferyl alacohol 36 trans-sinapyl alcohol CH=CH-CHOH 31 Coniferaldehyde 37 Sinapaldehyde CH=CH-CHO HCO 3 H OH R G R OCH 3 OH R S OCH 3 OH

8 8 H/G/S R HCO 3 S OH OCH 3 R G OH OCH 3 R H OH Proportion of p-hydroxyphenyl units < 1% The range of guaiacyl units varied from 24 to 35% and syringyl units from 65 to 75% of the identified lignin structures Ohra-aho, T, et al. J. Anal.Appl. Pyrolysis, 101 (2013)

9 9 S and G lignin pyrolysis derivatives Similar variation in S and G lignin pyrolysis derivatives among samples Ohra-aho, T, et al. J. Anal.Appl. Pyrolysis, 101 (2013)

10 10 Classification of Eucalyptus hybrids based on the pyrolysis lignin data by PCA Score plot of the two principle components shows how the samples are related to each other. Loading plot describes which guaiacyl (G) and syringyl (S) lignin structural units are important for the classification of samples seen in Score plot No grouping between samples observed, indicating that the original lignin structure different among Eucalyptus hybrids Same G and S side chain structures close to each others indicating that they are originated from similar type of lignin structural units Ohra-aho, T, et al. J. Anal.Appl. Pyrolysis, 101 (2013)

11 11 S/G ratio Comparison of methods Alkaline nitrobenzene oxidation Lignin is oxidatively cleaved to form aromatic carbonyl compounds i.e. syringaldehyde and vanillin as main products Only noncondensed (50% of the lignin) structures are reacted in nitrobenzene oxidation Py-GC/MS Lignin is thermally degraded to a mixture of phenols (p-hydroxyphenyl (H), guaiacyl (G) and syringyl (S) lignin units) by heating the samples in an inert atmosphere It is proposed that the phenols formed result from the cleavage of β-o-4 and some condensed linkages such as β-5 30% of guaiacyl and 90% of syringyl structures are expected to react Yield is expected to be dependent on the condensed structures present in lignin

12 12 S/G ratio for the Eucalyptus hybrids The differences between the methods are probably related to reaction mechanisms of lignin with Py-GC/MS and alkaline nitrobenzene oxidation methods Ohra-aho, T, et al. J. Anal.Appl. Pyrolysis, 101 (2013)

13 13 Carbohydrate composition Pyrogram of E. urophylla (IP) x E. grandis (IP) obtained at 580 C j f a b c d e g h minutes Degradation products of carbohydrates Origin b 1,5-Anhydro-4-deoxypent-1-en-3-ulose Xylose g 1,4-Anhydroxylopyranose Xylose d 1,5-Anhydroarabinofuanose Arabinose h 1,6-Anhydrogalactopyranose Galactose i 1,6-Anhydromannopyranose Mannose k 1,6-Anhydroglucopyranose (Levoglucosan) Glucose

14 14 Relative carbohydrate composition Comparison between methods Proportion of xylose higher by Py-GC/MS than by acid hydrolysis different products formed in pyrolysis and acid hydrolysis Content of mannose under the detection limit by Py-GC/MS

15 15 The relationship between Py-GC/MS and acid hydrolysis followed by HPLC (AH) PCA was utilized to see how the data obtained with both methods are related to each other. In general, variables close to each other correlate and give similar information about the sample. There was no correlation between glucose, xylose, arabinose and galactose units obtained by Py-GC/MS and acid hydrolysis, as the same carbohydrate units were not grouped together

16 16 Pulp characterization CARBOHYDRATE AND LIGNIN COMPOSITION IN EUCALYPTUS PULPS

17 17 Carbohydrate composition in Eucalyptus pulps Degradation products of carbohydrates Origin a Un id. pentose product from xyl Xyl b 1,5-Anhydro-4-deoxypent-1-en-3-ulose Xyl c 5-hydroxymethyl-2-tetrahydofuraldehyde-3-one Glc d 5-Hydroxymethyl-2-furaldehyde Glc e 1.4-Dideoxy-D-glycero-hex-1-enopyranose-3-ulose Glc f 1,4-Anhydroxylopyranose Xyl g 1,6-Anhydroglucopyranose (Levoglucosan) Glc Same Eucalyptus wood (E. grandis (Coffs Harbour) x[e.urophylla (R) x E.glopulus (R)]) was cooked to kappa 50, 35 and 15 using Soda-AQ and kraft pulping process Carbohydrate composition was analyzed by Py-GC/MS and acid hydrolysis followed by HPLC

18 18 Relative carbohydrate content in Eucalyptus pulps Similar trends in carbohydrate composition obtained with both methods

19 19 Comparison between the methods Clear linear relationship between the methods for both components

20 20 Lignin composition and content in Eucalyptus pulps Decrease of oxygen containing structures indicate degradation of β-o-4 bond in cooking

21 21 Conclusion Lignin analysis by Py-GC/MS, including S/G ratio, was found to be widely applicable for the comparison of wood raw materials The Py-GC/MS method is not recommended for the comparison of carbohydrate content between wood raw materials Relative carbohydrate composition between Py-GC/MS and acid hydrolysis followed by HPLC differed Changes in relative carbohydrate content as well lignin content and composition in cooking can be followed simultaneously by Py- GC/MS

22 22 Acknowledgements This project was financially supported by the Academy of Finland and Brazilian CNPq (Effect of fibre wall chemistry on energy demand in wood defibration, Defibre, ) Suzano Pulp & Paper is thanked for providing the pulp samples via collaboration in EU project LignoDeco Thank you for your attention!

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