Environmental Engineering Reference
In-Depth Information
taBle 8.6
Promising Biomass Pretreatment technologies
method
description
advantages
disadvantages
low ph treatments
Dilute acid, co-current
0.5-3% sulfuric acid, 130-200°C, 3-15 atm,
2-30 min., 10-40 wt% solids
Monomeric hemicellulose sugars, increases
cellulose hydrolysis to near 100%
Costly materials of construction, high operating
pressures, hydrolysate conditioning (neutralization
required)
Dilute acid, flow-through
0-0.1% sulfuric acid, 190-200°C, 20-24
atm, 12-24 min, 2-4 wt% solids
Enhances hemicellulose and lignin removal
Challenging to implement commercially,
high water use results in high energy requirements
Hot water/steam
autolysis
Hot water, 160-190°C, 6-14 atm, 10-30
min, 5-30 wt% solids
No chemical additions, low capital and
operation cost
Incomplete hydrolysis of hemicellulose
high ph treatments
AFEX/FIBEX
Anhydrous ammonia, 70-90°C, 15-20 atm,
5 min, 60-90 wt% solids
Lower-cost vessels, hydrolysate
conditioning unnecessary
Incomplete hydrolysis of hemicellulose
ARP
10-15 wt% ammonia, 150-170°C, 9-17 atm,
10-20 min, 15-30 wt% solids
Enhances cellulose digestion, lignin removal
Less effective at softwood pulps
Lime
0.05-0.15 g Ca(OH)
2
/g biomass, 70-130°C,
1-6 atm, 1-6 hours, 5-20 wt% solids
Low temperature, atmospheric pressure;
low-cost and inherently safe materials
Longer reaction times required
solvent Pretreatments
Organosolv
50-80% methanol or ethanol, 180-210°C,
approximately 1 h, 2 wt% solids
Easy solvent recovery, lignin isolated as a
solid, carbohydrates isolated as a syrup
Complicated washing arrangements, higher energy
costs, explosion hazards
Ionic Liquids
5 wt% solids 130-150°C
Nonflammable, low vapor pressure, high
recoverability
Expensive, large antisolvent requirement, little
known about long-term prospects
Source:
Wyman, CE., et al.
Bioresour Technol
, 96, 1959-1966, 2005b; Larsen, et al. 2008; Liu, ZL.,
Appl Microbiol Biotechnol
, 73, 27-36, 2006 and Dadi, AP., Varanasi, S., and
Schall, CA.,
Biotechnol Bioeng,
95, 904-910, 2006.
