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Oral
Presentation 1-05
Evaluation of Carbonic Acid Pretreatment of Biomass
G.
Peter van Walsum, Robert McWilliams, Damon Yourchisin,
Kemantha
Jayawardhana, Vanessa Castleberry.
Department
of Environmental Studies, Baylor University
PO
Box 97266, Waco, TX,
76798-7266, USA
Telephone: (254) 710-6552; Fax: (254)710-3409; E-mail: GPeter_van_Walsum@Baylor.edu Carbonic acid (H2CO3) may
offer an alternative to sulfuric acid (H2SO4)
for pretreatment of biomass. This would
eliminate corrosion, scaling and waste generation problems associated with H2SO4. Unlike pretreatments that make use of water
only, H2CO3 allows some control of reaction pH by
manipulating CO2 pressure in the reactor. Batch pretreatment tests were carried out over a
variety of reaction severities.
Substrates tested included aspen wood, corn stover, whey permeate, xylan
and lactose. Pretreatment products were
analyzed for pH, UV absorption, soluble carbohydrate and organic acid
concentrations, toxicity to Saccharomyces
cerevisiae and enzymatic hydrolysis
rates.
Results showed that H2CO3 is an
effective catalyst for purified compounds, and appears to influence the size
distribution of released oligomers.
When applied to biomass substrates, H2CO3 appears
to reduce the final concentration of acids compared to a liquid hot water
pretreatment (LHWP) system. However,
the LHWP and H2CO3 systems appear to have little
difference in the amount of soluble sugars and degradation products
produced. Analysis of the toxicity of
the hydrolyzate to S. cerevisiae and
the kinetics of enzymatic hydrolysis of pretreated solids showed minor
improvements compared to LHWP samples.
Aspen Plus-based modeling showed that energy and capital cost
contributions of the carbonic acid system are comparable to the expenses offset
by the elimination of sulfuric acid.
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