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

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Experiences from the PDUMats GalbeDepartment of
Chemical EngineeringLund University
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Process Development Unit (PDU)

• PDU lab and process equipment
• 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
• Commissioned work for companies and universities
• Internal research

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Purpose of a Process Development Unit

• Lab scale

• PDU

• Pilot scale

• Industrial scale

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Process Development Unit (PDU) Steam pretreatment
unit
10 litre reactor 160 - 230 C Impregnation
with H2SO4 or SO2 or other catalysts
Main purposes Hydrolysis of hemicellulose Improve
the enzymatic hydrolysis of cellulose
Success A number of units constructed sold
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Pretreatment unit (small)

• 4-litre capacity
• Jacket for less heat losses
• Improved control of temperature
• Surface-coated flash-off vessel

Implemented in large reactor
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Steam pretreatment or acid hydrolysis?

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

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Dilute-acid hydrolysis

• Dilute-acid hydrolysis
• Concentrations typically less than 2
• Temperatures 180-220C
• Residence time usually lt 15 min
• One- or two-step hydrolysis
• Advantage rather fast and simple
• Drawback results in degradation products -gt may
  be difficult to ferment
• Pentose sugars -gt furfural
• Hexose sugars -gt HMF, formic and levulinic acid

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Acid hydrolysis of spruce One-step at two
temperatures
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By-products in one-step acid hydrolysis using a
temperature profile
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Steam pretreatment

• Addition of a catalyst during pretreatment
• Milder conditions than in acid hydrolysis
• Acid results in hydrolysis of the hemicellulose
• H2SO4, H3PO4, SO2
• Alkali mainly oligo- and polymers
• NaOH, NH3
• Enzymatic hydrolysis (SHF) or simultaneous
  saccharification and fermentation (SSF)

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Different materials behavedifferently

• Agricultural materials
• Wheat straw
• Corn stover
• Sugar cane bagasse
• Sorghum (sweet/fibre)
• Arundo donax
• Rice straw
• Hemp
• Barley straw
• Paja Brava
• Forest materials
• Spruce
• Pine
• Poplar
• Cypress
• Salix

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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
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High-WIS applications(WIS Water-Insoluble
Solids)

• High WIS is good
• Potentially higher sugar concentrations-gt Higher
  ethanol concentrations-gt Less energy
  requirements
• (or is it?)
• Increased viscosity
• Higher inhibitor concentrations
• Less available liquid-gt unfriendly environment
• Heat transport affected!
• pH control initially difficult
• OPTIMISATION!

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Higher dry-matter concentrations

• Terrafors (originally for solid-state
  fermentations)
• Difficult to control pH
• Mixing less efficient with increased liquefaction

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High-WIS hydrolysis quick tests
Rotating with steel balls for mixing
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High-WIS (SHF or SSF)Test of equipment
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First test of enzymatichydrolysis of spruce