Hot water extraction of wood and extract purification. FuBio JR2 WP1 Petri Kilpeläinen, Johanna Tanner Finnish Forest Research Institute

Transcription

1 Hot water extraction of wood and extract purification WP1 Petri Kilpeläinen, Johanna Tanner Finnish Forest Research Institute

2 Research partners Research organisations Aalto University, Aalto Finnish Forest Research Institute, Metla Lappeenranta University of Technology, LUT University of Helsinki, UHe University of Jyväskylä, UJy VTT Technical Research Centre of Finland, VTT Åbo Akademi University, ÅA Industrial partners Andritz Kemira Metsä Group Stora Enso UPM-Kymmene

3 The aim To get fundamental knowledge of pressurized hot water extraction (PHWE) To extract hemicellulose and lignin from sawdust To produce polymeric, water soluble hemicellulose Lignin as by-product Extracted sawdust is processed to novel pulps

4 Rawmaterials and pre-treatment Wood - Spruce sawdust - Birch sawdust PHWE - Lab scale, METLA, ÅA - Pilot scale, METLA, VTT - Supercritical, Aalto Delignification - Lab scale, Ujy - Pilot scale, VTT Separation and purification Products Low Mw Hydrolysis - Enzymatic, UHe - Acid, ÅA Monosugars Extract Concentration - Ultrafiltration, LUT High Mw Purification - EtOH precipitation, LUT, METLA - Oxidation, ÅA High Mw hemicelluloses Black liquor Acidification - METLA Lignin Refined products Fuels Barriers Composites Pulp

5 Extraction temperatures METLA ÅA VTT Aalto Gas Viscosity, diffusivity and dieletric constant of water changes at higher temperatures ph scale changes as pkw value of water changes

6 Lab scale

7 Batch extraction of fine spruce sawdust Accelerated solvent extraction (ASE) 350, Zr-type cell Temperature: C Solvent: distilled water Liquor/Wood ca 4/1 Pressure: 10 MPa Fine fraction mm of ground spruce sapwood

8 Possible to obtain polymeric hemicellulose at lower temperature with fine fraction 180 C Max yield TDS of extracts obtained at different temperatures (particle size mm vs fine fraction mm) Ethanol precipitated polymeric GGM from extracts obtained at different temperatures (particle size mm vs fine fraction mm)

9 PHW flow-through extraction of birch sawdust with ph buffer 10 g a.d. of birch sawdust 50 ml extraction vessel Temperatures C Bar 30 min extraction 4 ml/min flow rate 0.1 M acetate buffer ph 4.0, 4.2 and 4.6

10 Molar mass of xylan increases with (ph 4.0) buffer RID NO BUFFER Decreasing molar mass 180 C Mw 1.1 kda 170 C Mw 2.1 kda 160 C Mw 18.8 kda Retention time, min RID Decreasing molar mass BUFFER 170 C Mw 4.8 kda 160 C Mw 14.2 kda 180 C Mw 3.9 kda Retention time, min

11 Pulp yield, % of original dry wood Oxygen-alkali delignification of PHW extracted sawdust Spruce and birch PHW extraction residues were cooked for min at 170 C Liquor to wood ratio 5L/kg Pulp yields were lower after PHWE combined with oxygen-alkali cook Less lignin was dissolved since some lignin was dissolved during PHWE Spruce sawdust PHW extracted sawdust Cooking time, minutes

12 Supercritical water treatment Cellulose Dissolved poly- and oligomers Glucose Degradation products Target: Dissolution of crystalline cellulose in near- and supercritical water Produce cello-oligomers from cellulose Minimizing sugar losses by applying a short reaction time

13 Cellulose dissolution in subcritical and supercritical water Short reaction time t < 1 s Long reaction time t > 1 s Cellulose precipitate after 0.2 s treatment Microcrystalline cellulose (MCC), Pre-hydrolyzed Kraft pulp (PHK), Alkaline treated (mercerized)

14 Modeling

15 Modeling of PHWE Objective: Develop a model for the degradation of birch in a percolation reactor. Previous PHWE study for batch reactor (Borrega et al. 1 ). Models were fitted to describe the degradation of lignin, xylan and glucan. How do the parameters obtained from the batch experiments fit the new data from percolation cooks? Schematic diagram of the flow-through percolation reactor and associated elements used for the hot water extractions of wood. 1. Borrega, M., Nieminen, K., and Sixta, H. (2011). Degradation kinetics of the main carbohydrates in birch wood during hot water extraction in a batch reactor at elevated temperatures, Biores. Technol. 102(22),

16 % o.d.w % o.d.w Model It is assumed that the hot liquor moves as a plug flow Initially the reactor only partly filled with hot liquor the reactions occur only in the hot section. Once a wood component has been dissolved, it stays in the reactor only for a short time before it is washed out and cooled down less further reaction products than in a batch reactor. Partial differential equations describe the time developments of the various 0,0 products ,0 3,5 3,0 2,5 2,0 1,5 1,0 0,5 200 C Glucooligosacharides (GOS) 5 Glucose Batch Hydroxymethylfurfural (HMF) 4 Other degradation products (Dp) Flow-through Time (min) Time (min) Flow rate 100 ml/min

17 Flow rate (l/min) Modeling flow-through PHWE of spruce sawdust utilizing Modde (partial least squares method) Average Mw GGM content of the PHWE extract mg/g Temperature ( C) Temperature ( C) A combination of low PHWE temperature and low flow rate dissolves highest molecular mass GGM, but with lower yield The model can be used to choose process conditions for PHWE in order to produce desired GGM properties

18 From lab to pilot scale

19 Example of stepwise batch PHWE process of spruce sawdust in a semi-pilot scale (30 l vessel) extraction Average Mw of spruce sawdust extract (kda) step PHWE 3-step PHWE 160 C/40 min 170 C/60 min 180 C/3 h washing at 50 C/30 min Stepwise PHWE dissolved GGM with high average Mw in the 1 st step. The Mw was clearly decreased in the 2 nd and 3 rd steps. PHWE processes in VTT s 30 l extraction vessel are reproducible, when looking at e.g. average molecular mass of the extracts in the first two steps of the two separate processes

20 Pilot scale (300 L) extraction vessel

21 PHWE flow-trough extraction examples in pilot scale Spruce at 170 C Birch at 160 C with ph 4.0 buffer ph stabilization during extraction Extracts to ultrafiltration and purification Results Spruce Birch Sawdust weight o.d. [kg] 53 kg 73 kg Time when collected [min] min min min min ph Hemicellulose yield [wt%] 4 wt% 7 wt% 3 wt% 6 wt% Mw [kda] 13 kda 8 kda 14 kda 8 kda

22 Lignin from pilot scale extraction Extracted sawdust was cooked with soda-aq to remove lignin Solution was acidified to precipitate sulfur free lignin Lignin was purified to remove inorganics Purified lignin was used to make biocomposites

23 Separation and purification of extracts

24 Recovery of high molar mass hemicelluloses in pilot scale Operation principle: CR-350 Concentrate Filter cassette Drainage support Membrane Feed Permeate From Metso Paper High shear rate CR-filters Commercial, hydrophilic 10 kda regenerated cellulose membrane (Alfa Laval) 60 C, 2 bar, rotor velocity m/s

25 Ultrafiltrations can be done continuously without losing filtration capacity

26 Extract can be concentrated and molar mass (Mw) of hemicellulose increases during extraction Possible to achieve the TDS and Mw of hemicellulose required for film manufacturing Increase in TDS content and Mw of hemicellulose have a clear effect on capacity Filtration capacity with spruce extracts higher than with birch extracts Three different birch extract filtrations Birch extracts need further purification to obtain better filtration results

27 Summary Fundamental knowledge obtained to up-scale system from lab to pilot scale Possible to extract polymeric, water-soluble hemicellulose from spruce and birch Produced lignin can be utilized to make biocomposites Purification and concentration of hemicelluloses can be done continuously with ultrafiltration

28 Acknowledgements Aalto Lasse Tolonen Marc Borreca Herbert Sixta Metla Petri Kilpeläinen Sanna Hautala Johanna Tanner Veikko Kitunen Olli Byman Teemu Tikkanen Zhiqiang Li Kaisu Leppänen Hannu Ilvesniemi LUT Mari Kallioinen Elsi Koivula Tuomas Nevalainen Mika Mänttäri Uhe Maija Tenkanen Ujy Joni Lehto Raimo Alén VTT Marjatta Kleen Tarja Tamminen ÅA Andrey Pranovich Risto Korpinen Jan-Erik Raitanen Chunlin Xu Jarl Hemming Jens Krogell Henrik Grénman Tapio Salmi Stefan Willför Kemira Marcus Lillandt