Carbonic Acid Pretreatment of Biomass
This project sought to address six objectives, outlined below. The objectives were met through the completion of ten tasks. 1) Solidify the theoretical understanding of the binary CO2/H2O system at reaction temperatures and pressures. The thermodynamics of pH prediction have been improved to include a more rigorous treatment of non-ideal gas phases. However it was found that experimental attempts to confirm theoretical pH predictions were still off by a factor of about 1.8 pH units. Arrhenius experiments were carried out and the activation energy for carbonic acid appears to be substantially similar to sulfuric acid. Titration experiments have not yet confirmed or quantified the buffering or acid suppression effects of carbonic acid on biomass. 2) Modify the carbonic acid pretreatment severity function to include the effect of endogenous acid formation and carbonate buffering, if necessary. It was found that the existing severity functions serve adequately to account for endogenous acid production and carbonate effects. 3) Quantify the production of soluble carbohydrates at different reaction conditions and severity. Results show that carbonic acid has little effect on increasing soluble carbohydrate concentrations for pretreated aspen wood, compared to pretreatment with water alone. This appears to be connected to the release of endogenous acids by the substrate. A less acidic substrate such as corn stover would derive benefit from the use of carbonic acid. 4) Quantify the production of microbial inhibitors at selected reaction conditions and severity. It was found that the release of inhibitors was correlated to reaction severity and that carbonic acid did not appear to increase or decrease inhibition compared to pretreatment with water alone. 5) Assess the reactivity to enzymatic hydrolysis of material pretreated at selected reaction conditions and severity. Enzymatic hydrolysis rates increased with severity, but no advantage was detected for the use of carbonic acid compared to water alone. 6) Determine optimal conditions for carbonic acid pretreatment of aspen wood. Optimal severities appeared to be in the mid range tested. ASPEN-Plus modeling and economic analysis of the process indicate that the process could be cost competitive with sulfuric acid if the concentration of solids in the pretreatment is maintained very high (~50%). Lower solids concentrations result in larger reactors that become expensive to construct for high pressure applications.
- Research Organization:
- Bayor University
- Sponsoring Organization:
- USDOE; USDOE - Office of Solar Thermal, Biomass Power, and Hydrogen Technologies (EE-13)
- DOE Contract Number:
- FC36-01GO11070
- OSTI ID:
- 882226
- Report Number(s):
- DOE/GO/11070final; TRN: US200716%%207
- Country of Publication:
- United States
- Language:
- English
Similar Records
Bioconversion of plant biomass to ethanol. Final report, December 1, 1979-December 31, 1980
A technical and economic analysis of acid-catalyzed steam explosion and dilute sulfuric acid pretreatments using wheat straw or aspen wood chips
Related Subjects
ACTIVATION ENERGY
AGRICULTURAL WASTES
BIOMASS
CARBOHYDRATES
CARBONATES
CARBONIC ACID
ECONOMIC ANALYSIS
ENZYMATIC HYDROLYSIS
FORECASTING
MAIZE
PRODUCTION
SUBSTRATES
SULFURIC ACID
THERMODYNAMICS
TITRATION
WATER
WOOD
biomass
pretreatment
carbonic acid
inhibition
aspen-plus modeling
enzymatic hydrolysis