Experiences from the PDU Mats Galbe Department of Chemical Engineering Lund University

 PDU: lab and process equipment o Research in bench-scale, i.e., max size 100 litre fermentor vessel  National facility placed at Lund University, mainly financed by the Swedish Energy Agency o Commissioned work for companies and universities o Internal research Process Development Unit (PDU)

Purpose of a Process Development Unit Lab scale Increased know-how Tests of new ideas Create models… Research Test of process configs. Optimisation Products & By-products Development PDU Pilot scale Evaluation Test of methodology Final optimisation Data for scale-up Verification Industrial scale

Process Development Unit (PDU) Steam pretreatment unit 10 litre reactor °C Impregnation with H 2 SO 4 or SO 2 or other catalysts Main purposes Hydrolysis of hemicellulose Improve the enzymatic hydrolysis of cellulose Success: A number of units constructed & sold

Pretreatment unit (small) 4-litre capacity Jacket for less heat losses Improved control of temperature Surface-coated flash-off vessel Implemented in large reactor

Steam pretreatment or acid hydrolysis?  What do we actually mean? o Steam pretreatment renders a material suitable for further processing (e.g, by enzymatic hydrolysis)  With or without catalyst (acid or base) o Acid hydrolysis (strong or dilute) ideally produces monomers that can be used without further treatment

Dilute-acid hydrolysis Dilute-acid hydrolysis: –Concentrations typically less than 2% –Temperatures °C –Residence time usually < 15 min –One- or two-step hydrolysis –Advantage: rather fast and simple –Drawback: results in degradation products -> may be difficult to ferment Pentose sugars -> furfural Hexose sugars -> HMF, formic and levulinic acid

Acid hydrolysis of spruce One-step at two temperatures

By-products in one-step acid hydrolysis using a temperature profile

Steam pretreatment Addition of a catalyst during pretreatment Milder conditions than in acid hydrolysis –Acid results in hydrolysis of the hemicellulose H 2 SO 4, H 3 PO 4, SO 2 –Alkali mainly oligo- and polymers NaOH, NH 3 –Enzymatic hydrolysis (SHF) or simultaneous saccharification and fermentation (SSF)

Different materials behave… …differently  Agricultural materials –Wheat straw –Corn stover –Sugar cane bagasse –Sorghum (sweet/fibre) –Arundo donax –Rice straw –Hemp –Barley straw –Paja Brava  Forest materials o Spruce o Pine o Poplar o Cypress o Salix

PDU – International partner Borregaard, Norway: Steam pretratment Chemtex, Italy: SSF, steam pretreatment Cargill, Germany: Steam pretreatment Mitsui Engineering & Shipbuilding, Japan: SSF Nagurjana Hills, India: SSF NBE Sweden: Hydrolysis, analysis, fermentation SGCC (State grid of China): Project and cooperation SEKAB: SSF, analysis Taurus: Pretreatment and fermentation … CTH KTH Brazil-EU: Partner in Cane Biofuel NILE (EU): SSF, pretreatment (Partner) University of Florida University of Georgia National Renewable Energy Labs (NREL), USA … Currently building full- scale plant in Italy

High-WIS applications (WIS: Water-Insoluble Solids) High WIS is good… –Potentially higher sugar concentrations -> Higher ethanol concentrations -> Less energy requirements …(or is it?) –Increased viscosity Higher inhibitor concentrations Less available liquid -> unfriendly environment Heat transport affected! pH control initially difficult OPTIMISATION!

Higher dry-matter concentrations o Terrafors (originally for solid-state fermentations) o Difficult to control pH o Mixing less efficient with increased liquefaction

High-WIS hydrolysis quick tests Rotating with steel balls for mixing

High-WIS (SHF or SSF) Test of equipment

First test of enzymatic hydrolysis of spruce