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Biorefineries and platform chemicals: Key terms, quiz and sources

Understanding Chemicals / Module 13: Biorefineries and platform chemicals Wrap-up

Biorefineries and platform chemicals: review

Key terms

Biorefinery
A plant or cluster that separates biomass into intermediate streams and converts them into a range of fuels, chemicals, materials, food, feed and energy.
Lignocellulose
The structural material of plant cell walls: cellulose and hemicellulose bound together by lignin.
Cellulose
A linear polymer of glucose joined by beta links that pack into hard-to-attack crystals; 35-50% of most plant material.
Hemicellulose
A branched polymer of mainly five-carbon sugars such as xylose, easily hydrolysed by dilute acid.
Lignin
A phenolic network polymer that glues plant fibres; usually burned for energy because no enzyme splits it cleanly.
Platform
A core intermediate (C6 sugars, C5 sugars, syngas, lignin, oil, pyrolysis oil) linking feedstocks to products.
Building block chemical
A molecule with several functional groups from which a family of derivatives can be made, like ethylene in petrochemistry.
Pretreatment
A thermal or chemical step, such as steam explosion with dilute acid, that opens biomass so enzymes can reach the cellulose.
Cellulase
A mixture of enzymes (cellobiohydrolases, endoglucanases, beta-glucosidase) that hydrolyses cellulose to glucose.
Titre, rate, yield
The three fermentation metrics: product concentration (g/L), productivity (g/L/h) and carbon conversion (g product per g sugar).
Simultaneous saccharification and fermentation (SSF)
Running enzymatic hydrolysis and fermentation in one vessel so the organism consumes glucose before it inhibits the enzymes.
Syngas
A mixture mainly of carbon monoxide and hydrogen made by gasifying biomass or other carbon sources.
Fast pyrolysis
Heating finely ground biomass to about 500 C in under 2 seconds without oxygen to make up to 75% bio-oil.
Transesterification
Swapping the glycerol in a triglyceride for another alcohol such as methanol, giving fatty acid methyl esters and glycerol.
Drop-in chemical
A bio-based molecule identical to a petrochemical, such as bio-ethylene, which uses existing plants and markets.
Dextrose equivalent (DE)
The reducing sugar content of a starch hydrolysate as a percentage of dry solids; higher DE means more complete hydrolysis.
Corn wet milling
Steeping and grinding corn in water to separate starch, gluten, fibre and germ, then refining the starch into many products.
Levulinic acid
A five-carbon keto acid made by acid treatment of six-carbon sugars, with formic acid as co-product; a DOE top-12 building block.

Try it in the table

  • Open the Bio-based polyethylene and MEG tile and compare its scale with Braskem's 200,000 t plant; then open Ethylene and use the 1.7 t ethanol per t ethylene figure to estimate how much Bioethanol one world-scale cracker's output would require.
  • Open the Glycerine tile and check how its price and supply have moved since biodiesel expanded; compare with Werpy and Petersen's 2004 range of 0.60-0.90 dollar/lb and their 0.05 dollar/lb floor.
  • Open the Lactic acid and PLA tile and look for current PLA capacity; compare it with NatureWorks' 140,000 t reported by Task 42 and with the Polyethylene (LDPE, LLDPE) tile's market size to see how small bio-plastics remain.
  • Open the Furfural and furanics (FDCA) tile and see whether FDCA has moved beyond pilot scale; then open Purified terephthalic acid and PET resin to judge the size of the market FDCA would need to break into.
  • Open the Maize and Sugar commodity tiles and compare their prices per tonne; use Dale and Kim's net corn cost of about 70% of purchase price to estimate the starch cost a wet mill actually carries.
  • Open the Industrial enzymes tile and look at which enzyme classes dominate sales; compare with Kent's 2010 figure of 3.5 billion dollars, over half proteases and nearly 40% carbohydrases.

Final quiz

Roughly what share of annual plant biomass is carbohydrate, according to Kamm and colleagues?

Of about 170 billion tonnes a year, roughly 75% is carbohydrate, 20% lignin and 5% oils, proteins and other compounds.

Iogen's enzymatic hydrolysis took 5-7 days at 50 C. Why is SSF at a compromise 37 C unattractive to Iogen?

Tolan reports poor results from SSF: lost rate at the compromise temperature plus microbial contamination.

Why must most organic acid fermentations be neutralised, and what does it cost?

Producing the salt then converting it back to free acid uses base and acid and creates by-product salts such as gypsum.

What did Werpy and Petersen set as minimum productivity for commodity diacid fermentations?

They required about 2.5 g/L/h so capital costs do not dominate, alongside fermentation cost at or below 0.25 dollar per pound.

Which statement about the Biofine process is correct?

Reactor 1 runs at 210-220 C for seconds, reactor 2 at 190-200 C for about 20 minutes; lignin and tar leave as char that powers the plant.

A sugar costs 180 euro per tonne and petroleum 175 euro per tonne (Thoen and Busch, 2000-03). Why can sugar-based commodities still lose on cost?

Equal price per tonne of feed becomes very unequal per tonne of product once roughly half the mass leaves as CO2 or water.

What fraction of kraft pulping lignin is burned in recovery boilers, according to Pye?

Over 70 million tonnes a year are made and more than 99% burned; perhaps 100,000 t is sold for its chemical value.

Which feature did NatureWorks PLA and DuPont's 1,3-propanediol share?

PLA and PTT (Sorona) are novel polymers; their monomers came from corn-derived dextrose by fermentation, next to existing wet mills.
Next module: Bioplastics: PLA, PHA, bio-PE and starch blends →

Sources for this module

  • Kamm, B., Gruber, P.R. & Kamm, M. (eds.), Biorefineries: Industrial Processes and Products, Vols 1-2, Wiley-VCH, 2006 · Vol 1 Ch 1 (pdf pp. 35-64), Ch 2 (pp. 73-96), Ch 3 (pp. 99-114), Ch 5 (pp. 147-156), Ch 6 (pp. 160-165), Ch 7 (pp. 173-190), Ch 9 (pp. 221-235), Ch 10 (pp. 237-252), Ch 11 (pp. 258-275), Ch 12 (pp. 311-312), Ch 14 (pp. 349-368), Ch 15 (pp. 372-379), Ch 16 (p. 384), Ch 17 (pp. 414-421); Vol 2 Ch 1 (pp. 466-470), Ch 5 (pp. 628-633), Ch 12 (pp. 802-818), Ch 13 (pp. 821-832), Ch 14 (pp. 834-856), Ch 16 (pp. 896-908)
  • IEA Bioenergy Task 42 (de Jong, Higson, Walsh & Wellisch), Bio-based Chemicals: Value Added Products from Biorefineries, 2012 · pdf pp. 4-29
  • Werpy, T. & Petersen, G. (eds.), Top Value Added Chemicals from Biomass, Vol I: Results of Screening for Potential Candidates from Sugars and Synthesis Gas, US DOE (PNNL/NREL), 2004 · pdf pp. 8-70
  • Kent, J.A. (ed.), Handbook of Industrial Chemistry and Biotechnology, 12th ed., Springer, 2012: Ch 30 Industrial biotechnology (Chotani et al.), Ch 31 Industrial enzymes and biocatalysis (McAuliffe), Ch 33 Biomass conversion (Decker et al.), Ch 34 Animal and vegetable fats, oils and waxes (Lusas et al.), Ch 35 Sugar and other sweeteners (Godshall) · pdf pp. 1137-1166, 1184-1201, 1249-1297, 1374-1395, 1403-1412
  • Wittcoff, H.A., Reuben, B.G. & Plotkin, J.S., Industrial Organic Chemicals, 2nd ed., Wiley, 2004: Ch 13 Fats and oils, Ch 14 Carbohydrates · pdf pp. 437-460, 461-484