Kinetics of Product Formation in the H2S-Promoted Pyrolysis of 2-Methyl-2-pentene

Author(s):  
DAVID A. HUTCHINGS ◽  
KENNETH J. FRECH ◽  
FREDERIC H. HOPPSTOCK
Author(s):  
Teresa Romero Cortes ◽  
Jaime A. Cuervo-Parra ◽  
Víctor José Robles-Olvera ◽  
Eduardo Rangel Cortes ◽  
Pablo A. López Pérez

AbstractEthanol was produced using mucilage juice residues from processed cocoa with Pichia kudriavzevii in batch fermentation. Experimental results showed that maximum ethanol concentration was 13.8 g/L, ethanol yield was 0.50 g-ethanol/g glucose with a productivity of 0.25 g/L h. Likewise, a novel phenomenological model based on the mechanism of multiple parallel coupled reactions was used to describe the kinetics of substrate, enzyme, biomass and product formation. Model parameters were optimized by applying the Levenberg-Marquardt approach. Analysis of results was based on statistical metrics (such as confidence interval), sensitivity and by comparing calculated curves with the experimental data (residual plots). The efficacy of the proposed mathematical model was statistically evaluated using the dimensionless coefficient for efficiency. Results indicated that the proposed model can be applied as a way of augmenting bioethanol production from laboratory scale up to semi-pilot scale.


1983 ◽  
Vol 413 (1 Biochemical E) ◽  
pp. 71-87 ◽  
Author(s):  
J. E. BAILEY ◽  
M. HJORTSO ◽  
S. B. LEE ◽  
F. SRIENC

Holzforschung ◽  
2019 ◽  
Vol 73 (7) ◽  
pp. 681-687 ◽  
Author(s):  
Honglei Chen ◽  
Xin Zhao ◽  
Yu Liu ◽  
Fangong Kong ◽  
Xingxiang Ji

Abstract Sugar-containing hydrolysates as byproducts of dissolving pulp production could be a source of alcohol production, but the presence of fermentation inhibitors hampers this utilization route. In the present study, nine types of phenolic inhibitors were found and their removal by ligninases gave satisfactory results. Laccase removed 73.1% of phenolic inhibitors and produced three new aromatic compounds, whereas the combination of laccase and lignin peroxidase (as a dual-enzyme treatment) resulted in a removal rate of 91.7% without new product formation. Xylose as the main sugar in the hydrolysate was retained with a 90% yield, regardless of the enzymatic treatment, which modified, however, the kinetics of yeast growth. Laccase improved cells’ maximum specific growth rate (vmax) from 0.115 to 0.154 and reduced the saturation constant (Ks) from 53.4 to 42.5, whereas the dual-enzyme system improved vmax to 0.206 and reduced Ks to 42.44. The greater vmax and the smaller Ks imply a better growth rate, and accordingly, the dual-enzyme system is better suited for removing phenolic inhibitors.


1994 ◽  
Vol 297 (1) ◽  
pp. 131-136 ◽  
Author(s):  
T Lindhout ◽  
G Willems ◽  
R Blezer ◽  
H C Hemker

The inhibition equilibrium and kinetics of association and dissociation of the binding of three types of recombinant tissue factor pathway inhibitor (TFPI), namely full-length TFPI, C-terminal-truncated TFPI, and TFPI without the third Kunitz domain (TFPI1-161), to factor Xa have been measured. Formation and dissociation of the complexes were monitored by continuous measurement of the changes in the rate of hydrolysis of a peptidyl-p-nitroanilide substrate. Progress curves of product formation were fitted to a set of equations describing a one-step bimolecular inhibitory reaction in the presence of a competing substrate. For full-length TFPI the rate constants of association (kon) and dissociation (koff) were (5.1 +/- 0.7) x 10(6) M-1.s-1 and (2.6 +/- 0.9) x 10(-4)s-1 respectively. Thus, although the inhibition constant (50 pM) is far below the plasma concentration (2.5 nM) of TFPI, the half-time for transition to equilibrium in plasma is rather long (66s). The truncated forms of TFPI differ in that they have a 4-fold lower kon value but a similar dissociation rate constant. Therefore the inhibition constant, Ki, is 4-fold higher (0.2 nM) and the half-time to achieve equilibrium is prolonged to 250 s. The kon values of full-length and C-terminal-truncated TFPI, but not that of TFPI1-161, were found to decrease with increasing ionic strength.


1969 ◽  
Vol 173 (1032) ◽  
pp. 411-420 ◽  

The theory of the kinetics of enzyme cascades is developed. Two types of cascades are recognized, one in which the products are stable ( open cascades ) and another in which the products are broken down ( damped cascades ). It is shown that it is a characteristic of a cascade that the final product appears after a certain lag phase. After this lag phase, the velocity of product formation can be very rapid. It is shown that whereas open cascades will always show a complicated time–product relation, damped cascades can under certain circumstances resemble a simple enzymic reaction. Because the relation between the over-all reaction velocity in the extrinsic coagulation cascade and the concentration of any of the proenzymes in this cascade is a hyperbolic one, it is concluded that this cascade is of the damped type rather than the open type.


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