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51.
52.
Schell Danial J. Hinman Norman D. Wyman Charles E. Werdene Pamela J. 《Applied biochemistry and biotechnology》1990,24(1):287-297
Applied Biochemistry and Biotechnology - Cellulase, an enzyme that catalyzes the breakdown of cellulose into glucose, is produced inside fungal cells and secreted into the surrounding media.... 相似文献
53.
Wyman Charles E. Woodward Jonathan Goodman Barbara J. 《Applied biochemistry and biotechnology》1994,48(1):iii-iv
Applied Biochemistry and Biotechnology - 相似文献
54.
Applied Biochemistry and Biotechnology - 相似文献
55.
Hinman Norman D. Wright John D. Hogland William Wyman Charles E. 《Applied biochemistry and biotechnology》1989,(1):391-401
The economic impact of conversion of xylose to ethanol for a wood-to-ethanol plant was examined, and the maximum potential
reduction in the price of ethanol from utilization of xylose is estimated to be 0.42 per gallon from a base case price of0.42 per gallon from a base case price of
1.65. The sensitivity of the price of ethanol to the yield, ethanol concentration and rate of the xylose fermentation was
also examined, and the price of ethanol is most affected by changes in yield and ethanol concentration, with rate of lesser
importance. Current performances of various xylose conversion biocatalysts were analyzed, andC. shehatae andP. stipitis appear to be the best yeasts. 相似文献
56.
Ethanol can be directly blended with gasoline, reacted with isobutylene to form the oxygenated fuel additive ethyl tert-butyl
ether (ETBE), or burned directly as a neat fuel. Blends of either ethanol or ETBE with gasoline force engines set for gasoline
to run lean and can substantially reduce carbon monoxide emissions. ETBE also lowers the overall vapor pressure, thereby cutting
back on smog-forming emissions. Neat ethanol further reduces smog formation since it has a low volatility, the photochemical
reactivity of ethanol and its combustion products is low, and low levels of smog producing compounds are formed by ethanol
combustion. Neat ethanol also offers good engine performance owing to its high heat of vaporization, high octane, and low
flame temperature.
Fermentation stoichiometry reveals that many feedstocks are expensive for fuels production even considering coproduct credits
and ignoring conversion costs, whereas lignocellulosic feedstocks cost much less than their value. Furthermore, the quantities
of lignocellulosics are projected to be ample even for neat ethanol production. Release of carbon dioxide during fermentation
concentrates almost all the heat of combustion from the solid carbohydrate portion in liquid ethanol. Since the carbon dioxide
released during production and use of ethanol is recycled during growth of biomass, ethanol utilization doesn’t contribute
to the accumulation of carbon dioxide in the atmosphere and possible global warming. 相似文献
57.
Impact of fluid velocity on hot water only pretreatment of corn stover in a flowthrough reactor 总被引:1,自引:0,他引:1
Flowthrough pretreatment with hot water only offers many promising features for advanced pretreatment of biomass, and a better
understanding of the mechanisms responsible for flowthrough behavior could allow researchers to capitalize on key attributes
while overcoming limitations. In this study, the effect of fluid velocity on the fate of total mass, hemicellulose, and lignin
was evaluated for hot water only pretreatment of corn stover in tubular flow through reactors. Increasing fluid velocity significantly
accelerated solubilization of total mass, hemicellulose, and lignin at early times. For example, when fluid velocity was increased
from 2.8 to 10.7 cm/min, xylan removal increased from 60 to 82% for hot water only pretreatment of corn stover at 200°C after
8 min. At the same time, lignin removal increased from 30 to 46%. Dissolved hemicellulose was almost all in oligomeric form,
and solubilization of hemicellulose was always accompanied by lignin release. The increase in removal of xylan and lignin
with velocity, especially in the early reaction stage, suggests that chemical reaction is not the only factor controlling
hemicellulose hydrolysis and that mass transfer and other physical effects may also play an important trole in hemicellulose
and lignin degradation and removal. 相似文献
58.
John D. Wright Charles E. Wyman Karel Grohmann 《Applied biochemistry and biotechnology》1988,18(1):75-90
Simultaneous saccharification and fermentation (SSF) processes for producing ethanol from lignocellulose are capable of improved
hydrolysis rates, yields, and product concentrations compared to separate hydrolysis and fermentation (SHF) systems, because
the continuous removal of the sugars by the yeasts reduces the end-product inhibition of the enzyme complex. Recent experiments
using Genencor 150L cellulase and mixed yeast cultures have produced yields and concentrations of ethanol from cellulose of
80% and 4.5%, respectively. The mixed culture was employed because B.clausenii has the ability to ferment cellobiose (further reducing end-product inhibition), while the brewing yeastS. cerevisiae provides a robust ability to ferment the monomeric sugars. These experimental results are combined with a process model to
evaluate the economics of the process and to investigate the effect of alternative processes, conditions, and organisms. 相似文献
59.
High solids simultaneous saccharification and fermentation of pretreated wheat straw to ethanol 总被引:1,自引:0,他引:1
A. Mohagheghi M. Tucker K. Grohmann C. Wyman 《Applied biochemistry and biotechnology》1992,33(2):67-81
Wheat straw was pretreated with dilute (0.5%) sulfuric acid at 140°C for 1 h. Pretreated straw solids were washed with deionized
water to neutrality and then stored frozen at –20°C. The approximate composition of the pretreated straw solids was 64% cellulose,
33% lignin, and 2% xylan. The cellulose in the pretreated wheat straw solids was converted to ethanol in batch simultaneous
saccharification and fermentation experiments at 37°C using cellulase enzyme fromTrichoderma reesei (Genencor 150 L) with or without supplementation with β–glucosidase fromAspergillus niger (Novozyme 188) to produce glucose sugar and the yeastSaccharomyces cerevisiae to ferment the glucose into ethanol. The initial cellulose concentrations were adjusted to 7.5, 10, 12.5, 15, 17.5, and 20%
(w/w). Since wheat straw particles do not form slurries at these concentrations and cannot be mixed with conventional impeller
mixers used in laboratory fermenters, a simple rotary fermenter was designed and fabricated for these experiments. The results
of the simultaneous saccharification and fermentation (SSF) experiments indicate that the cellulose in pretreated wheat straw
can be efficiently fermented into ethanol for up to a 15% cellulose concentration (24.4% straw concentration). 相似文献
60.
The uncatalyzed hydrolysis and removal of xylan from corn stover is markedly enhanced when operation is changed from batch
to continuous flow through conditions, and the increase in hemicellulose removal with flow rate is inconsistent with predictions
by widely used first-order kinetic models. Mass transfer or other physical effects could influence the hydrolysis rate, and
two models reported in the literature for other applications were adapted to investigate whether incorporation of mass transfer
into the kinetics could explain xylan removal in both batch and continuous flow through reactors on a more consistent basis.
It was found that a simple leaching model and a pore diffusion/leaching model could describe batch and flow through data with
accuracy similar to that of conventional batch models and could provide a more rational explanation for changes in performance
with flow rate. 相似文献