June 24 27, 2014 Seville, Spain. Proceedings

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1 June 7, Seville, Spain Proceedings

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3 PROCEEDINGS -7 June Seville, Spain

4 Institute of Natural Resources and Agrobiology of Seville (IRNAS-CSIC), Editors: J.C. del Río, A. Gutiérrez, J. Rencoret and Á.T. Martínez Printed in Spain, Cover design: E.D. Babot ISBN:

5 th European Workshop on Lignocellulosics and Pulp KRAFT LIGNIN DEPOLYMERISATION BY BASE CATALYSED DEGRADATION (BCD) - THE EFFECT OF PROCESS PARAMETERS ON CONVERSION DEGREE AND STRUCTURAL FEATURES OF BCD-FRACTIONS Detlef Schmiedl *, Sarah Böringer, Rainer Schweppe, Tiina Liitiä, Stella Rovio, Tarja Tamminen, Jorge Rencoret, Ana Gutiérrez, José C. del Rio Fraunhofer Institute for Chemical Technology, Pfinztal, Germany; VTT-The Technical Research Center of Finland, Espoo, Finland; IRNAS-CSIC, Seville, Spain (*detlef.schmiedl@ict.fraunhofer.de) ABSTRACT The objective of the study is the generation of oxy-aromatic compounds (monomer, oligomer) from Eucalyptus- Kraft-lignin via multi-stage processes. These processes ( st base catalysed degradation & nd separation of the organic phase from reactor water) have to be feasible in bio refineries & in new Pulp-mill bio refineries as a new technology module. The Eucalyptus-Kraft-lignin (Suzano Pulp & Paper) was used for catalyzed conversion into oxy aromatics. Subsequently, the effect of process parameters: catalyst & catalyst conc., mineral content, p: bars, min), T: C)) was investigated. Liquid-liquid extraction of reactor water (ph=) was performed with MIBK for isolation of the monomer rich phase. The BCD fractions (oils) & (tars) were characterized regarding their yields via carbon balance, & their composition. A characterization of the monomer composition was done (GC-MS/FID & EA (CHONS), P-NMR, D-NMR (HSQC), TGA). Types of monomers were summarized into groups (guaiacols (G), syringols (S), catechols (C )). Oligomer degradation products in the oil were characterized by Infusion MS Ion Trap & the composition of the oligomer phase by Py GC-MS, SEC, EA, P-NMR, D-NMR (HSQC) & TGA. On the one hand, depending on the botanical source & the lignin recovery process (Organosolv, Kraft etc.), useful lignins differ in their structure (inter unit linkages) & monomer composition, mineral & sulphur content, M W, M N. These substrate factors effecting the degradation process during the catalysed cleavage of aryl-aryl-ether & aryl-methyl-ether bonds. On the other hand, process factors e. g.: p,,, catalyst conc. & type of alkaline elements have a main effect on the cleavage processes, on the yield & composition of the monomer rich phase (oil), on the molecular characteristic (Mw, Mn, OH-number (aliphatic & phenolic )) of the oligomer rich phase (tar) & on the carbon balance. To get an overview about the main & side effects in such complex situation, the study on the Kraft-lignin was done using DoE (Box-Behnken). A detailed evaluation regarding the main & side effects of process factors on the yield of oil & tar, on the concentration of (G), (S) & (C ) in the oil phase, on the carbon balance, on M W & M N of the tars as well on functional groups (OH-number, differentiated into aliphatic & phenolic), presence of inter unit linkages & methoxy groups will be given. I. INTRODUCTION Depletion of crude oil, an increase in the greenhouse gas concentration, economical/ecological challenges of the pulp & paper industry force into the utilization of lignocellulose biomass. Only by economical biomass conversion processes the production of sustainable bio-based materials, chemicals, & semi-finished chemical goods will be reasonable. Lignin (renewable resource) contains aromatic structures, & has sustainable & economical potential in bio based chemicals & materials. Lignin depolymerisation for the generation of phenolic building blocks has been investigated over some decades. The degradation of lignin (Kraft-lignin, Organosolvlignin) in alkaline, hot compressed solution, so called base catalysed degradation - BCD is based on the selective catalytic cleavage of inter unit linkages ( -O-, -O-, -O-) & methyl-aryl-ether bonds in the presence of strong bases (e.g. NaOH, KOH) [-]. Under defined conditions the generation of a monomer rich phase (BCD-oil) & an oligomer rich phase (BCD-tar) is possible. A detailed study was done regarding the BCD of Eucalyptus-Kraft-lignin (wt. % of ash), supported by DoE (Box-Behnken). The high mineral content of the lignin was used as additional catalytic active component. The experiments were done in a plug flow reactor at selected T, & C, with selected additional NaOH of, & wt.-% as well as at selected reaction times of, & min respectively. The pressure was ~ -bars. The BCD-oil & BCD-tar phases were analysed by weight, EA (CHONS), P-NMR, D-NMR (HSQC) & TGA. Additionally, the BCD-oils were analysed by GC-MS/FID (composition of monomer oxy aromatic compounds (G, S, C)) & by infusion MSD Ion Trap (APCI negative) (oligomer composition). Furthermore, the acetylated BCD-tars were analysed by SEC regarding their molecular weight (M N, M W ). The D assessment of the complex data sets was supported by the software Statgraphics centurion XV. Based on the analysis results the carbon balance was used for the description of the conversion degree into BCD-oil and BCD-tar over the test cube. 7

6 th European Workshop on Lignocellulosics and Pulp II. EXPERIMENTAL GC-MS/FID: Monomers were determined according a method describe in []. Elemental analysis (NCHS & O): EA was performed according a method described in []. P-NMR- Analysis: OH-Number was determined according a method described in [6]. D-NMR- Analysis (HSQC): D-NMR-analysis was done according a method described in [7]. SEC-Analysis: M N &M W of acetylated samples were determined according a method described in [8]. III. RESULTS AND DISCUSSION Depending on the process parameters the Kraft-lignin could be converted into -% of BCD-oil & -7% of BCD-tar (by carbon balance, Figure. &.). The liberation of primary monomer cleavage products (G & S) & the formation of secondary monomer cleavage products (C) depend significantly on T, & the concentration of NaOH. The highest amounts of C (approx..wt. % of lignin) were generated at the process parameter combination: T: C, t: min & wt.-% of NaOH (Figure.). Conc NaOH=, Conc NaOH=, Conc NaOH=, Carbon in oil [ wt.- % lignin],,, 7,,, Carbon in oil [ wt.- % lignin],,, 7,,, Carbon in oil [ wt.- % lignin],,, 7,,, Carbon in oil [wt.-% lignin] 7,, Carbon in oil [wt.-% lignin] 7,, Carbon in oil [wt.-% lignin] 7,, Figure. Conversion degree-carbon balance of used lignin over the BCD-oil (z-axis: - %) depending on process parameters (y-axis: T: - [ C], : - [min], NaOH- [%]: % left, % centre, % right. Conc NaOH=, Conc NaOH=, Conc NaOH=, Carbon in tar [wt.-% lignin] ,, Carbon in t ar [w t.-% lignin],,,, 6 6, 7 7, 8 8, Carbon in tar [wt.-% lignin] ,, Carbon in t ar [w t.-% lignin],,,, 6 6, 7 7, 8 8, Carbon in tar [wt.-% lignin] ,, Carbon in t ar [w t.-% lignin],,,, 6 6, 7 7, 8 8, Figure. Conversion degree-carbon balance of used lignin over the BCD-tar (z-axis: 8%) depending on the process parameters (y-axis: T: - [ C], : - [min], NaOH- [%]: % left, % centre, % right. P-NMR analyses on selected BCD-oils show an increase in the phenolic OH-number depending on BCD process conditions. P-NMR analyses on corresponding BCD-tars illustrate more or less the same trend in the phenolic OH-number. The used Kraft-Lignin showed a lower phenolic OH (Table.). The stronger the process conditions (: min, C 8: min, C : min, C,const.NaOH:%) the higher the phenolic OH number, indicating additional de-methylation. An additional de-methoxylation is remarkable. Para-hydroxy phenolic units were also formed (Table.). During the BCD aliphatic OH-groups were lost (Table.). Table. Results of P-NMR of Eucalyptus-Kraft-Lignin & of some BCD-oils & tars regarding aliphatic & phenolic OH-number & their distribution into condensed & S, G, C, para-hydroxy-phenyl. sample Aliphatic Cond. & Syringols Guaiacols Catechols para Phenolic Total K-Lignin BCD oil BCD oil BCD oil BCD tar BCD tar BCD tar

7 7, 7, 7, Conc NaOH=,, Conc NaOH=,, Conc NaOH=,, Yield Guaiacols [ wt.- % lignin],,,,,,,,,, Yield Guaiacols [ wt.- % lignin],,,,,,,,,, Yield Guaiacols [ wt.- % lignin],,,,,,,,,, Conc NaOH=, Conc NaOH=, Conc NaOH=, Yield Syringols[ wt.- % lignin],,,,,,,,,, Yield Syringols[ wt.- % lignin],,,,,,,,,, Yield Syringols[ wt.- % lignin],,,,,,,,,, 7, 7, 7, Conc NaOH=, Conc NaOH=, Conc NaOH=, Yield Catechols [wt.-% lignin],,,,,,,,,, Yield Catechols [wt.-% lignin],,,,,,,,,, Yield Catechols [wt.-% lignin],,,,,,,,,, th European Workshop on Lignocellulosics and Pulp Guaiacols Syringols Catechols NaOH conc wt.-% Yield Guaiacols [wt.-% lignin] Yield S yringols [wt.-% lignin] 7 9 Yield C atechols [wt.-% of lignin], Yield Guaiacols [wt.-% lignin] Yield S yringols [wt.-% lignin] 7 9 Yield C atechols [wt.-% of lignin], Yield Guaiacols [wt.-% lignin] Yield S yringols [wt.-% lignin] 7 9 Yield C atechols [wt.-% of lignin], Figure. Yield of G (z-axis: - wt.-% of lignin), S (z-axis: - wt.-% of lignin) & C (z-axis: - wt.-% of lignin) depending on the BCD process parameters (T [ C], [min], Conc. NaOH. TG-Analyses on BCD-oils illustrate that ~ -6 wt.-% of the samples are volatile up to a temperature of C. The residues represent the non-volatile, oligomer fraction in BCD-oils. Infusion MSD Ion Trap analysis on BCD-oils illustrates a complex picture of single charged & multi charged oligomer molecules in the scanning range from to amu. Kraft-lignin & BCD-oils Kraft-lignin & BCD-tars Figure. D-NMR (HSQC, C / H ppm) Spectra of Eucalyptus-Kraft-Lignin, BCD-Oils, 8, (left) & of BCD-Tars, 8, (right), (LE LE8 LE: points in DoE, Box -Behnken), generated by BCD. D-NMR analyses (HSQC) on some BCD-oils illustrate the absence of inter-unit linkages -O- & - ` (Figure.). D-NMR analyses (HSQC) on selected BCD-tars show that the presence/absence of inter unit linkages of the type -O- & - ` depends on the process conditions (Figure.). The results of SEC on Kraft-lignin & on BCDtars illustrate a significant reduction on M W : 7-g/moles & M N : -6g/moles as well as on M W /M N :. The Kraft-lignin showed following values for M W : 869g/moles, M N : g/moles, M W /M N : 6. (Figure.). 77

8 th European Workshop on Lignocellulosics and Pulp Figure. Result of SEC (M N, M W ) on BCD-tars depending on parameters, [min], T [ C] & NaOH [wt.-%]. IV. CONCLUSIONS BCD of hard wood Kraft-lignin leads to the formation of primary cleavage products (guaiacols, syringols) & secondary cleavage products (catechols, p-phenolics) by additional de-methylation & de-methoxylation. The formation of the monomers depends on the process parameters: T, & catalyst conc.. The inter-unit linkages ( - O-, -O-, - `resinol) are not more present in BCD-oils & in the oligomer BCD-fractions depending on the process parameters. The formed oligomer material shows lower M W, M N & M W /M N than the Kraft-lignin, & contains very high amounts of phenolic - functional group. The aliphatic OH -group will be lost during BCD of lignin. The oligomer main product (BCD-tar) shows also interesting structures for material applications. The properties are adjustable by process parameters. Further investigations are necessary. V. ACKNOWLEDGEMENT The authors would like to thank the company Suzano Pulp & Paper, the national funding organisations (Agency for Renewable Resources, BMELV, Germany; TEKES, Finland; INIA, Spain). VI. REFERENCES [] Miller, J.E.; Evans, L.R.; Mudd, J.E.; Brown, K.A.: Batch Microreactor studies of lignin depolymerisation by bases.. Aqueous solvents, SAND-8, Sandia National Laboratories, Albuquerque, New Mexico, USA, -. [] Vigneault, A.; Johnson, D.K.; Chornet, E.: Advance in the thermal depolymerisation of lignin via basecatalysis. In: Science In Thermal And Chemical Biomass Conversion, 6,, -9. Edited by A.V. Bridgwater and D.G.B. Boocock, CPL Press, Newbury Berks, UK. [] Thring, R.W., Chornet, E., Overend, R.P. Fractionation of woodmeal by prehydrolysis and thermal organosolv. Alkaline depolymerisation, chemical functionality, and molecular weight distribution of recovered lignins and their fractions. Can. J. Chem. 99, 7, [] Schmiedl, D.; Endisch, S.; Pindel, E.; Rückert, D.; Unkelbach, G.; Schweppe, R. Base Catalysed Degradation of lignin for the generation of oxy-aromatic compounds Possibilities and challenges. Erdöl, Erdgas, Kohle,, 8, Heft, 7 6. [6] Granata, A., Argyropoulos, D.S. -Chloro-,,,-tetramethyl-,,-dioxaphospholane, a reagent for the accurate determination of the uncondensed and condensed phenolic moieties in lignins. J. Agric. Food Chem. 99,, 8-. [7] Rencoret J., Marques G., Gutiérrez A., Ibarra D., Li J., Gellerstedt G., Santos J.I., Jiménez-Barbero J., Martínez A.T. and del Río J.C. Structural characterization of milled wood lignin from different eucalypt species. Holzforschung, 8, 6, -6. [8] Baumberger, S.; Abaecherli, A.; Fasching, M.; Gellerstedt, G.; Gosselink, R. Hortling, B.; Li, J.; Saake, B., de Jong, E. (7): Molar mass determination of lignins by size-exclusion chromatography: towards standardisation of the methods. Holzforschung, 7, 6,