INTEGRATED POSSIBILITIES OF PRODUCING CHEMICALS AND BIOFUELS IN CHEMICAL PULPING International Forest Biorefining Conference (IFBC) May 9-11, 2017, Thunder Bay, ON, Canada Raimo Alén University of Jyväskylä, Finland Laboratory of Applied Chemistry
OUTLINE GENERAL ASPECTS PRETREATMENT OF WOOD CHIPS Acidic and alkaline conditions BY-PRODUCTS OF KRAFT PULPING Lignin, aliphatic carboxylic acids, and extractives BY-PRODUCTS OF OTHER PULPING METHODS CONCLUSIONS
GENERAL ASPECTS
RAW MATERIAL AGES (Mabee & Saddler, 2008)
BIOREFINERY CONVERSION METHODS PHYSICAL UPGRADING METHODS (drying, pulverisation, briquetting, and pelletizing) CHEMICAL AND BIOCHEMICAL METHODS (hydrolysis followed by fermentation or chemical conversion) THERMOCHEMICAL METHODS (torrefaction, pyrolysis, gasification, liquefaction, and combustion) OTHER METHODS (e.g., production of composites or fractionation followed by chemical conversion - cellulose derivatives)
PROCESS SCHEME FOR THE CONVERSION OF BIOMASS-DERIVED CARBOHYDRATES
PRODUCT GROUPS FROM THERMAL CONVERSION OF CELLULOSIC BIOMASS
PRINCIPAL CONVERSION ROUTES FOR CELLULOSIC BIOMASS TO PRODUCE VARIOUS ENERGY SOURCES
INTEGRATED BIOREFINERY CONCEPT The first industrial biorefineries were operated in the pulp and paper industry already about 160 years ago
From forest to paper
BIOMASS BIOREFINERY CONCEPTS Chemical and thermochemical conversion techniques Energy Electricity Heat Biodiesel Wood Non-wood crops (agricultural residues) Natural-growing plants Pretreatment (acidic or alkaline) Carbohydrates Other materials Pulping (alkaline process) By-product recovery Extractives Black liquor Energy Chemicals Chemicals Ethanol Other chemicals FIBER
PRINCIPLES FOR THE INTEGRATED PRETREATMENT PROCESS FIBER IS THE MAIN PRODUCT EFFICIENT RECOVERY OF COOKING CHEMICALS AND EXTRACTIVES SULFUR-FREE NOVEL BY-PRODUCTS SUITABLE BALANCE BETWEEN THE CARBOHYDRATE AND LIGNIN DEGRADATION PRODUCTS STRAIGHTFORWARD SEPARATION TECHNIQUES VERSATILE MODIFICATION POSSIBILITIES
COMMERCIAL PULPING METHODS Method Yield (% of wood) Chemical pulping 35-60 Kraft, polysulfide kraft, prehydrolysis kraft Soda-anthraquinone (AQ) Acid sulfite, bisulfite, AQ alkali sulfite Multistage sulfite Semichemical pulping 65-85 Neutral sulfite semichemical (NSSC) Soda Chemimechanical pulping 80-90 Chemithermomechanical (CTMP) Chemigroundwood (CGWP) Mechanical pulping 91-98 Thermomechanical (TMP) Refiner mechanical (RMP) Stone groundwood (SGWP) Pressure groundwood (PGWP)
KRAFT PULPING Chemical pulping accounts for 70 % of the total worldwide production Currently about 90 % of chemical pulps (about 130 million tons) are produced by the kraft (sulfate) process White liquor containing mainly the active cooking chemicals NaOH and Na 2 S is used for cooking the chips
BASIC PRINCIPLES OF TYPICAL PRETREATMENT STAGES IN KRAFT PULP MILL
Typical pre-treatment phases in the alkaline delignification
PRETREATMENT OF WOOD CHIPS Acidic conditions
ACIDIC PRETREATMENTS AUTOHYDROLYSIS (only with H 2 O) HYDROLYSIS WITH AQUEOUS MINERAL ACIDS (mainly with H 2 SO 4 )
CHEMICAL COMPOSITION OF BIRCH- AND PINE-BASED HYDROLYSATES (% of the initial dry matter) Component Birch Pine Carbohydrates 12.7 9.6 Monosaccharides 1.4 1.8 Oligo- and polysaccharides 11.3 7.8 Uronic acids 0.4 0.6 Furans 0.1 0.1 Volatile acids 1.6 0.5 Acetic acid 1.5 0.4 Formic acid 0.1 0.1 Lignin 2.1 1.1 Total 16.9 11.9 The chips are treated at 150 o C for 90 min (liquor-to-wood ratio 5 L/kg)
PRETREATMENT OF WOOD CHIPS Alkaline conditions
THE FIRST PHASE OF ALKALINE (KRAFT) PULPING A RATHER LOW SELECTIVITY AN INTENSE ALIPHATIC ACID FORMATION COMPARED TO THE LIGNIN DISSOLUTION MOST OF THE EXTRACTIVES ARE REMOVED TURPENTINE SAPONIFICATION OF ESTERS ( FATTY AND RESIN ACIDS) NEUTRAL SUBSTANCES ( NONSAPONIFIABLES )
Behavior of the major wood components during kraft pulping of pine (Aurell, R. & Hartler, N., Svensk Papperstidn. 68(3)(1965)59-68)
MAIN REACTIONS OF POLYSACCHARIDES IN ALKALINE PULPING - 1
MAIN REACTIONS OF POLYSACCHARIDES IN ALKALINE PULPING -2
THE SOLUBLE DRY MATTER FORMED DURING THE ALKALINE PRETREATMENT OF BIRCH (% of the initial dry matter) (Lehto, J. & Alén, R., J. Wood Chem. Technol. 33(2)(2012)77-91) Component 6 (b) 8 (b) Aliphatic carboxylic acids 7.4 9.1 Volatile acids (c) 5.3 6.0 Hydroxy acids (d) 2.1 3.1 Lignin 2.5 3.5 Other organics (e) 2.4 3.5 Total 12.3 16.1 (a) - The chips are treated at 150 o C for 90 min (liquor-to-wood ratio 5 L/kg); (b) - alkali charge (% of NaOH on o.d. feedstock); (c) - acetic and formic acids; (d) - mainly glycolic, lactic, 2- hydroxybutanoic, 3,4-dideoxy-pentonic, 3-deoxy-pentonic, xyloisosaccharinic, and glucoisosaccharinic acids; and (e) - mainly extractives and carbohydrates
SOME PARAMETERS OF THE ALKALINE PRETREATMENTS (30 min, 150 o C (pine) or 160 o C (birch)) Alkali charge, % of NaOH on wood Mass ratio aliphatic acids/lignin Residual alkali, g/l 8 10 Pine Birch Pine Birch 2.2 2.2 2.3 1.8 1.8 0.4 2.8 2.0 ph (after treatment) 11.0 10.0 11.9 11.0
Estimated production (tons/year) of the organic fractions formed during the alkaline pretreatments (8 % NaOH on wood/30min/150 o C) a Fraction Pine Birch Aliphatic acids 88,100 83,700 Volatile acids 37,000 45,200 Hydroxy acids 51,100 38,500 Lignin 40,200 38,200 Extractives 39,100 24,000 Total 167,400 145,900 a Calculated for an annual production of 500,000 o.d. tons of unbleached pulp.
HARVESTING RESIDUES and BARK 47 CONVERSION i) BURNING ii) GASIFICATION iii) CHEMICAL TREATMENT SYNTHESIS GAS FT-PROCESS Energy Chemicals (e.g., ethanol) Energy (elecric power, steam) Liquid fuel Chemicals TREE 100 FIBER 25 50 % PRETREATMENT (acid or alkali) DELIGNIFICATION i) KRAFT ii) SODA-AQ iii) O 2 /alkali 15-20 % Energy SPENT LIQUOR 30-35 % BLACK LIQUOR RECOVERY PROCESSES RECOVERY FURNACE (diesel fuels) Organic fractions Cooking chemicals Energy Cooking chemicals
BY-PRODUCTS OF KRAFT PULPING Black liquor - general
WOOD (100) % Cellulose 40-45 Hemicelluloses 25-35 Lignin 20-30 Extractives < 5 EXTRACTIVES (< 5) UNBLEACHED PULP (45-55) % Cellulose 60-75 Hemicelluloses 20-30 Lignin < 5 ORGANICS (5) BLACK LIQUOR (40-50) % Aliphatic acids 40-45 Lignin 35-45 Other organics 10-15 OXYGEN-DELIGNIFIED and BLEACHED PULP (40-50) % Cellulose 80-85 Hemicelluloses 15-20 Lignin -
COMPOSITION OF THE DRY MATTER OF BIRCH AND PINE KRAFT BLACK LIQUORS (% of the total dry matter) Component Birch Pine Lignin 25 31 Aliphatic carboxylic acids 33 29 Volatile acids (a) 12 10 Hydroxy acids (b) 21 19 Other organics 9 7 Extractives 3 4 Carbohydrates (c) 5 2 Miscellaneous 1 1 Inorganics (d) 33 33 (a) - Acetic and formic acids; (b) - mainly glycolic, lactic, 2-hydroxybutanoic, 3,4-dideoxypentonic, 3-deoxy-pentonic, xyloisosaccharinic, and glucoisosaccharinic acids; (c) - mainly hemicellulose-derived fragments; and (d) - including the sodium bound chemically to organics
COMPOSITION OF THE DRY MATTER OF PINE AND BIRCH KRAFT BLACK LIQUORS AND ALKALINE BIRCH HYDROLYSATE (% of the total dry matter) Component Pine (a) Birch (a) Birch (b) Lignin 31 25 16 Aliphatic carboxylic acids 29 33 43 Formic acid 6 4 3 Acetic acid 4 8 26 Glycolic acid 2 2 1 Lactic acid 3 3 2 2-Hydroxybutanoic acid 1 5 3 3,4-Dideoxy-pentonic acid 2 2 1 3-Deoxy-pentonic acid 1 1 <1 Xyloisosaccharinic acid <1 4 2 Glucoisosaccharinic acid 7 3 2 Others 2 1 3 Other organics 7 9 16 Inorganics 33 33 25 (a) - Black liquor and (b) - alkaline pretreatment hydrolysate (8 % NaOH, 150 o C, 90 min)
MAIN UTILIZATION POSSIBILITIES COMBUSTION IN THE RECOVERY FURNACE (for recovering energy and cooking chemicals) GASIFICATION (for recovering energy and cooking chemicals as well as for producing chemicals) RECOVERY OF ORGANIC FRACTIONS (for making fuels and chemicals)
BY-PRODUCTS OF KRAFT PULPING Black liquor - lignin
RECOVERY OF LIGNIN IN PRACTICAL APPLICATIONS, IT IS ADVANTAGEOUS TO USE CO 2 FROM FLUE GAS (ph 9.5, yield 35 %) FOLLOWED BY THE USE OF PURE CO 2 UNDER PRESSURE (ph 8) (at 80 o C, <20 atm, total yield 75 %) THE LIBERATION OF PHENOLIC HYDROXYL GROUPS (pk a 9-11) TAKES PLACE LIGNIN PRECIPITATES pk a VALUES OF CARBOXYLIC ACIDS ARE 3-5
SOME PRACTICAL DATA (Alén, R., Patja, P. & Sjöström, E., Tappi 62(11)(1979)108-109; Alén, R., Sjöström, E. & Vaskikari, P., Cellulose Chem. Technol. 19(1985)537-541) TAPPI
SOME PRACTICAL DATA (Alén, R., Patja, P. & Sjöström, E., Tappi 62(11)(1979)108-109; Alén, R., Sjöström, E. & Vaskikari, P., Cellulose Chem. Technol. 19(1985)537-541)
INFLUENCE ON THE HEATING VALUE OF BLACK LIQUOR HEATING VALUES: Black liquor (15-35 % water and 25-40 % inorganics, and about 45 % organics) 12-15 MJ/kg d.s.; lignin 22-27 MJ/kg; aliphatic carboxylic acids 5-18 MJ/kg; and extractives about 35 MJ/kg DECREASES IN HEATING VALUE (MJ/kg d.s.): 5-10 % (precipitated lignin yield 35 %) and 15-25 % (precipitated lignin yield 75 %) BEHAVIOR OF COMBUSTION PROPERTIES: Carbonated black liquors swell clearly less than untreated black liquors
SOME UTILIZATION POSSIBILITIES OF THE PRECIPITATED LIGNIN PHENOLIC RESINS POLYURETHANES PHENOLS (AND CARBON FIBER) FUEL PURPOSES
BY-PRODUCTS OF KRAFT PULPING Black liquor aliphatic carboxylic acids
Schematic representation of a possible black liquor fractionation process
One of the process alternatives (Alén and Kumar 2016)
THE MAIN ALIPHATIC CARBOXYLIC ACIDS OF BLACK LIQUOR
UTILIZATION POSSIBLITIES OF ALIPHATIC CARBOXYLIC ACIDS ONLY A MINOR PROPORTION OF ALIPHATIC CARBOXYLIC ACIDS CAN BE UTILIZED AS SUCH IN THE FORM OF THEIR SODIUM SALTS ( their liberation, pk a values 3-5) REALISTIC FRACTIONS: VOLATILE ACIDS including formic and acetic acids LOW-MOLAR-MASS HYDROXY ACIDS (with 2-4 carbon atoms) including glycolic, lactic, and 2-hydroxy-butanoic acids HIGH-MOLAR-MASS HYDROXY ACIDS (with 5 and 6 carbon atoms) including 3,4-dideoxy-pentonic, 3-deoxypentonic, and xylo- and glucoisosaccharinic acids
UTILIZATION POSSIBLITIES OF ALIPHATIC CARBOXYLIC ACIDS LIBERATION WITH MINERAL ACIDS (mainly with H 2 SO 4 ) OR ELECTRODIALYSIS FRACTIONATION AND PURIFICATION BY VACUUM DISTILLATION (0.067-0.173 kpa) OR ION-EXCLUSION CHROMATOGRAPHY
UTILIZATION POSSIBLITIES OF ALIPHATIC CARBOXYLIC ACIDS FORMIC, ACETIC, GLYCOLIC, AND LACTIC ACIDS ARE COMMERCIALLY IMPOPRTANT CHEMICALS BY REDUCTION (i.e., the production of polyalcohols) BY OXIDATION (i.e., the production of polycarboxylic acids) BY ESTERIFICATION (i.e., the production of emulsifying agents) BY OTHER METHODS (e.g., the production of various polyesters or a wide range of derivatives)
CONDENSATION OF LOW-MOLAR-MASS ACIDS (Alén, R. & Sjöström, E., Acta Chem. Scand. B 34(1980)633-636)
BY-PRODUCTS OF KRAFT PULPING Black liquor - extractives
CRUDE TALL OIL (CTO) TALL OIL SOAP the removal from the evaporated black liquor by skimming the liberation of carboxylic acids (resin and fatty acids) with H 2 SO 4 CTO (the average yield 30-50 kg/ton of pulp, corresponding to 50-70 % of the initial amount) PURIFICATION AND FRACTIONATION BY VACUUM DISTILLATION (3-30 mbar, 170-290 o C): LIGHT OIL 10-15 % FATTY ACIDS 20-40 % ROSIN 25-35 % PITCH RESIDUE 20-30 %
UTILIZATION OF CRUDE TALL OIL SOAP AN INTERESTING NEW APPROACH PRODUCTION OF BIODIESEL BY PYROLYSIS PRODUCTION OF Na 2 CO 3 (no external H 2 SO 4 is needed) NOTE ALSO VOLATILE TURPENTINE (5-10 kg/ton of pulp)
PYROGRAM OF TALL OIL SOAP (at 750 o C for 20 s) (Lappi, H. & Alén, R., BioResources 6(2011)5121-5138)
The main products formed in the pyrolysis experiments (700 o C and 20 s) with hot-water-extracted birch sawdust (left) and with soda-aqdelignified pulp from hot-water-extracted birch sawdust (right). Letters indicate compound groups to which identified products belong: A (anhydrosugar derivatives), B (benzene derivatives), C (cyclopentenone derivatives), E (catechol and benzenediol derivatives), F (furan derivatives), G (guaiacol derivatives), I (indene derivatives), L (lactone derivatives), N (naphthalene derivatives), P (phenol derivatives), S (syringol derivatives), X (fatty acids derivatives), and Y (pyrone derivatives). Ghalibaf et al. 2017
Liquefaction of black liquor McKeough, Alén, Oasmaa & Johansson, Holzforschung 44(1990)445-448
BY-PRODUCTS OF OTHER PULPING METHODS
THE MAIN METHODS ACID SULFITE PULPING VARIOUS ORGANOSOLV METHODS
COMPOSITION OF BIRCH AND SPRUCE ACID SULFITE SPENT LIQUORS (kg/ton pulp) Component Birch Spruce Lignosulfonates 435 510 Carbohydrates 380 270 Monosaccharides 305 215 Oligo- and polysaccharides 75 55 Aliphatic carboxylic acids 130 70 Acetic acid 75 30 Aldonic acids 55 40 Extractives 40 40 Others 55 30
ORGANOSOLV PULPING Pulping in the presence of organic solvents ( organosolv methods ) dates back to the beginning of the 1930s (T.N. Kleinert) Was not considered seriously for practical use until in the 1980s For both woods and non-woods The most important solvents include alcohols (e.g., methanol and ethanol), aliphatic carboxylic acids (e.g., formic and acetic acids), phenols (e.g., phenol and cresol) and many other systems also in the presence of alkaline or acidic catalysts
SIMPLIFIED FLOWCHART OF ORGANOSOLV PROCESSES
CONCLUSIONS PRETREATMENT OF WOOD CHIPS UNDER VARYING CONDITIONS OFFERS AN INTERESTING APPROACH FOR MAKING BIOPRODUCTS BLACK LIQUOR ORGANICS REPRESENT A HUGE AMOUNT OF RENEWABLE RAW MATERIAL AND THE PARTIAL RECOVERY OF THESE FRAGMENTS SEEMS ATTRACTIVE (AND TECHNICALLY POSSIBLE) THERE ARE SOME POTENTIAL UTILIZATION POSSIBILITIES FOR ALL THESE BY-PRODUCTS (CAN THESE PRODUCTS BE MARKETED?)