Pre-treatment Technologies Jean-Luc Wertz and Prof. Michel Paquot Lignofuels 2011 - 29 September 2011

PLAN Introduction Physical pre-treatments Chemical pre-treatments (e.g. organosolv) Physicochemical pre-treatments (e.g. steam explosion; AFEX) Biological pre-treatments Economic analysis (OPEX, CAPEX) Performance summary

Average composition of lignocellulosic biomass

Cellulose: molecular structure Glucose units linked by β 1-4 glycosidic bonds One reducing end and one non-reducing end Linear straight polysaccharide

Hemicelluloses High structural diversity Monomers: pentoses and hexoses Branched polysaccharides Example: xyloglucans as shown below

Lignin Monomers : 3 different monolignols (H, hydroxyphenyl; G, guaïacyl; S, syringyl) H G S

Lignin Cross-linked polymers of monolignols

Schematic of the role of pre-treatment Source: P. Kumar et al., 2009

Biomass pretreatment with water at high temperature and pressure Liquid hot water (LHW) Biomass pretreatment with water at high temperature and pressure

Inbicon’s hydrothermal pre-treatment pilot plant

Weak and strong acid hydrolysis 1 Weak acid: High-temperature (>160°C), continuous-flow process for low solids loadings Low-temperature (<160°C) batch process for high solids loadings 2. Strong acid: Powerful agents for cellulose hydrolysis and no enzymes are needed after the concentrated acid process

Alkaline hydrolysis Well known in the pulp and paper industry as kraft pulping

Extraction of lignin from Kraft pulp mill black liquor by the LignoBoost process Source: Metso, LignoBoost

Schematic of the MixAlco® process (Terrabon, Inc.) Source: Holtzapple et al., Terrabon

Organosolv processes Solvolytic cleavage of an alpha-aryl ether linkage by nucleophilic substitution; R=H or CH3; B=OH, OCH3

Some important organosolv processes Process Name Solvent / Additive Asam Water + sodium carbonate + hydroxide + sulfide + methanol / Anthraquinone Organocell Water + sodium hydroxide + methanol Alcell (APR) Water+ low aliphatic alcohol Milox Water + formic acid + hydrogen peroxide (forming peroxyformic acid) Acetosolv Water + acetic acid/Hydrochloric acid Acetocell Water + acetic acid Formacell Water + acetic acid + formic acid Formosolv Water + formic acid + hydrochloric acid

Lignol’s process based on water/ethanol pre-treatment Source: Lignol

CIMV process: formic acid / acetic acid / H2O lignocellulosic materials Formic Ac./Acetic Ac./Water heating filtration black liquors pulp Formic Ac./Acetic Ac./Water rinsing black liquors Water pulp water precipitation Water washing centrifugation Water solubles pulp lignins Acidified water Source: C. Vanderghem et al., ULg-GxABT washing lignins

CIMV process using acetic acid/formic acid/water Source: C. Vanderghem et al., ULg-GxABT , Time: 1h (-1), 2h (0), 3h(1). Temperature: 80°C (-1), 90°C (0), 107°C (1)

CIMV process using acetic acid/formic acid/water Source: C. Vanderghem et al., ULg-GxABT Temperature: 80°C (-1), 90°C (0), 107°C (1). FA/AA/W: 20/60/20 (-1) 30/50/20(0); 40/40/20 (1)

CIMV process using acetic acid/formic acid/water Source: C. Vanderghem et al., ULg-GxABT Time: 1h (-1), 2h (0), 3h(1). Temperature: 80°C (-1), 90°C (0), 107°C (1)

CIMV process using acetic acid/formic acid/water Source: C. Vanderghem et al., ULg-GxABT Temperature: 80°C (-1), 90°C (0), 107°C (1). FA/AA/W: 20/60/20 (-1) 30/50/20(0); 40/40/20 (1)

Oxidative delignification Hydrogen peroxide treatment Ozone treatment Wet oxidation: treatment with oxygen or air in combination with water at high temperature and pressure

Room temperature ionic liquids Main cations and anions in ionic liquids

Room temperature ionic liquids Different types of interaction present in imidazolinium-based ionic liquids

Room temperature ionic liquids Proposed mechanism for cellulose dissolution in EmimAc

Room temperature ionic liquids Hydrolysis of cellulose in a mixture of cellulases and an ionic liquid (HEMA) +

Steam explosion Schematic of the steam explosion process. 1, sample charging valve; 2, steam supply valve; 3, discharge valve; 4, condensate drain valve

ULg-Gembloux Agro-Bio Tech steam explosion pilot plant (Source: N ULg-Gembloux Agro-Bio Tech steam explosion pilot plant (Source: N. Jacquet et al.)

ULg-Gembloux Agro-Bio Tech steam explosion pilot plant (Source: N ULg-Gembloux Agro-Bio Tech steam explosion pilot plant (Source: N. Jacquet et al.)

Ulg-GxABT steam explosion pilot plant (Source: N. Jacquet et al.)

Ammonia pre-treatments Ammonia fiber explosion (AFEX™): biomass is exposed to liquid ammonia at high temperature and pressure and then pressure is reduced Ammonia recycle percolation (ARP): aqueous ammonia passes through biomass at high temperature, after which ammonia is recovered

What is AFEX™? Reactor Explosion Ammonia Recovery Expansion Recovered vapor Expansion Ammonia Recovery Biomass Treated Heat Ammonia Fiber Expansion Process Moist biomass is contacted with ammonia Temperature and pressure are increased Contents soak for specified time at temperature and ammonia load Pressure is released Ammonia is recovered and reused AFEX™ is a trademark of MBI

Biomass Conversion for Different Feedstocks Before and After AFEX Glucan conversion for various AFEX treated Feed stocks Switchgrass Sugarcane Bagasse DDGS Rice straw Corn stover Miscanthus Glucan conversion after enzymatic hydrolysis UT=No Pretreatment AFEX=Ammonia Pretreatment Excellent Biomass Conversion After AFEX Pretreatment

Carbon dioxide explosion High pressure carbon dioxide, and particularly supercritical carbon dioxide is injected into the reactor and then liberated by an explosive decompression

Mechanical/alkaline pre-treatment Continuous mechanical pre-treatment with the aid of an alkali

Biological pre-treatments White-rot fungi are the most efficient in causing lignin degradation Source: L. Goodeve, 2003 Source: R.A. Blanchette, 2006

Performance summary Pretreatment Decrystallization of cellulose Removal of hemicelluloses Removal of lignin Inhibitor formation Liquid hot water1) XX Weak acid1) Alkaline X Organosolv X3 Wet oxidation Steam explosion* 1) Ammonia fiber explosion (AFEX) CO2 explosion Mechanical/alkaline Biological XX: Major effect; X: Minor effect;; *: increases crystallinity; 1) alters lignin structure Inhibitors: furfural from hemicelluloses and hydroxymethylfurfural from cellulose and hemicelluloses

Performance summary All pretreatments partially or totally remove hemicelluloses Wet oxidation, AFEX and CO2 explosion reduce cellulose crystallinity Alkaline, organosolv, wet oxidation, mechanical/alkaline and biological partially or totally remove lignin High amounts of fermentation inhibitors are formed with liquid hot water, weak acid and steam explosion

ECONOMIC ANALYSIS: OPEX (Minimum Ethanol Selling Price), CAPEX Pretreatment OPEX ($/gal EtOH) CAPEX ($/gal annual capacity) Liquid hot water 1.65 4.57 Weak acid 1.35 3.72 Alkaline 1.60 3.35 Organosolv Wet oxidation Steam explosion Ammonia fiber explosion (AFEX) 1.40 Ammonia recycle percolation (ARP) 4.56 Ideal 1.00 2.51 Source: Eggeman et al., 2005 NB Enzyme cost: EUR 3/kg of produced cellobiose

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