PNNL-13501 - Pacific Northwest National Laboratory

Concentration (g/100g solution)
Concentration (g/100g solution)
0.80
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
2.50
2.00
1.50
1.00
0.50
0.00
without acid) hydrolysis (i.e., as in Figure 3), and the
hydrolysate were subjected to enzymatic treatment, the
enzymes would likely be even more effective because
mass transfer limitations and accessibility to the
hemicellulosic fraction would be minimized.
Processing Equipment
Xylose Concentrations
A B C D E Control
Enzyme
Glucose Concentrations
Based on observations during testing and filtration, and
the characteristics of the feed slurry, bench-scale
processing equipment was developed and modification of
an existing continuous flow system was initiated. A
Moyno feed pump, capable of pumping the feed slurry at
the conditions evaluated was also acquired. In addition,
since the acid hydrolysis was conducted at slightly
elevated pressure (to keep the reaction mixture in the
liquid phase), pressure letdown was required for the
continuous system. It has been observed, however, that if
the pressure is reduced through a small orifice or
instantaneously, the fiber particles break apart and are
more difficult to filter. Thus, a more amenable pressure
letdown system has been designed, and the hardware for
the system has been acquired.
Summary and Conclusions
Shortest Time
Medium Ti me
Longest Ti me
A B C D E Control
Enzyme
Figure 4. Enzyme hydrolysis of corn fiber
Shortest Time
Medium Ti me
Longest Ti me
The hemicellulosic fraction of corn fiber is a promising
source for providing 5-carbon sugars that can be
converted to value-added products. Observations from
Concentration (g/100g solution)
Concentration (g/100g solution)
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
Arabinose Concentrations
A B C D E Control
Enzyme
Mannose/Fructose Concentrations
Shortest Time
Medium Ti me
Longest Time
Shortest Time
Medium Ti me
Longest Time
A B C D E Control
Enzyme
the tests using acid and enzyme hydrolysis to recover the
hemicellulosic fraction are summarized below:
• Some hydrolysis options have been developed from
literature and test results. Based on the data to date,
one of the most attractive approaches is a two-step
process, using acid and enzyme hydrolysis. The data
suggest that this approach will result in high yields of
monosaccharides while minimizing formation of
degradation products.
• Thermochemical (with and without acid addition)
hydrolysis conditions have been identified, where
significant corn fiber solubilization takes place and
little or no degradation products are formed.
• Commercially available and relatively inexpensive
enzymes have been identified that are effective in
converting corn fiber hemicellulose to xylose and
arabinose.
• Bench-scale equipment was developed for continuous
thermochemical processing. The equipment was
selected based on observations made during the
testing.
Separations and Conversions 441