scholarly journals Kinetics of Secondary Reactions Affecting the Organosolv Lignin Structure

ChemSusChem ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4557-4566
Author(s):  
James R. Meyer ◽  
Huiyong Li ◽  
Jialiang Zhang ◽  
Marcus B. Foston
Keyword(s):  
Organosolv Lignin ◽  
Secondary Reactions ◽  
Kinetics Of ◽  
Lignin Structure

The mercury (63P1) photosensitized hydrogenation of ethylene. Kinetics of the reaction C2H5 + H2 = C2H6 + H

1968 ◽  
Vol 46 (20) ◽  
pp. 3275-3281 ◽  
Author(s):  
L. E. Reid ◽  
D. J. Le Roy
Keyword(s):  
Gas Phase ◽  
Molecular Hydrogen ◽  
Mercury Vapor ◽  
Experimental Conditions ◽  
Working Pressure ◽  
Extinction Coefficients ◽  
Secondary Reactions ◽  
Ethyl Radicals ◽  
Kinetics Of ◽  
Hydrogenation Of Ethylene

A quantitative study has been made of the reaction of ethyl radicals with molecular hydrogen in the gas phase in the temperature range 240 to 320 °C. The mercury (63Pi) photosensitized decomposition of hydrogen in the presence of ethylene was used to generate ethyl radicals. Extinction coefficients for the absorption of 2537 Å by mercury vapor were measured and Beer's law was shown to be obeyed under the experimental conditions used. The corrections required to allow for the nonuniformity of radical concentrations in the cell were small. After delineating the experimental conditions necessary to minimize secondary reactions, the rate constant (cm3 mole−1 s−1) for the reaction C2H5 + H2 = C2H6 + H was found to be given by log10k = 12.57 − 13.7/θ. Experiments in the presence of added carbon dioxide showed the absence of hot radical effects at the working pressure of 92 Torr of hydrogen.

Kinetics of the Mercury-Photosensitized Decomposition of Neopentane. Part III. The Secondary Reactions

1972 ◽  
Vol 50 (8) ◽  
pp. 1129-1133 ◽  
Author(s):  
E. Furimsky ◽  
K. J. Laidler
Keyword(s):  
Secondary Products ◽  
Secondary Reactions ◽  
Kinetics Of Formation ◽  
Kinetics Of

The following were identified as secondary products of the mercury-photosensitized decomposition of neopentane, and their maximal rates measured over a range of conditions: C2H4, C3H6, C3H8, i-C4H10, 2,2,3,3-tetramethylbutane, and 2,2,4,4-tetramethylpentane. A mechanism is proposed which explains the kinetics of formation of these products. It involves the reaction of H atom with i-C4H8 formed as a primary product; this leads to the formation of C4H9 which reacts further; one of its products is C3H6 which also reacts with H atoms.

Kinetics of vapor-phase secondary reactions of prompt coal pyrolysis tars

1987 ◽  
Vol 26 (9) ◽  
pp. 1831-1838 ◽  
Author(s):  
Michael A. Serio ◽  
William A. Peters ◽  
Jack B. Howard
Keyword(s):  
Vapor Phase ◽  
Coal Pyrolysis ◽  
Secondary Reactions ◽  
Kinetics Of

Pyrolysis of Hexadecane

1997 ◽  
Vol 62 (7) ◽  
pp. 1057-1069 ◽  
Author(s):  
Elena Barteková ◽  
Martin Bajus
Keyword(s):  
Hydrogen Transfer ◽  
Coke Formation ◽  
Tubular Reactor ◽  
Frequency Factor ◽  
Mass Ratio ◽  
Pyrolysis Products ◽  
Alkyl Radicals ◽  
Secondary Reactions ◽  
Increasing Temperature ◽  
Kinetics Of

The kinetics of thermal decomposition of hexadecane was studied in a flow tubular reactor from stainless steel. The experiments were performed in the temperature range of 700 to 780 °C for the mass ratio of steam to hydrocarbon 3 : 1. The hexadecane pyrolysis took place according to the first-order reaction with a frequency factor of 3.5 . 109 s-1 and an activation energy of 162 kJ mol-1. In the pyrolysis products there were above all 1-alkenes. From alkanes, methane and ethane and less propane were formed in a higher degree. The prevailing compounds are ethene and propene whose amount increases with increasing temperature and residence time. The content of 1-alkenes higher than 1-pentene decreases with increasing conversion which gives evidence of their decomposition owing to their lower stability in comparison with the lighter 1-alkenes. The formation of dienes (1,3-butadiene and propadiene) and benzene also confirmed the course of secondary reactions. The observed higher formation of hydrogen results from the reaction of steam with coke deposited on the walls of the reactor or with hydrocarbon radicals. The evidence of the coke formation is given also by the presence of carbon oxides whose amount grew with the pyrolysis severity. The high content of 1-hexene in comparison with the other higher 1-alkenes is probably caused by the isomerization of alkyl radicals by 1,5-hydrogen transfer.

MECHANICAL PULPING: Effect of autohydrolysis on the lignin structure and the kinetics of delignification of birch wood

2011 ◽  
Vol 26 (4) ◽  
pp. 386-391 ◽  
Author(s):  
Tiina Rauhala ◽  
Simopekka Suuronen ◽  
Herbert Sixta ◽  
Alistair W T King ◽  
Gerhard Zuckerstätter
Keyword(s):  
Birch Wood ◽  
Kinetics Of ◽  
Lignin Structure

Pyrolysis of methylcyclohexane

1987 ◽  
Vol 52 (6) ◽  
pp. 1527-1544 ◽  
Author(s):  
Ulrika Králíková ◽  
Martin Bajus ◽  
Jozef Baxa
Keyword(s):  
Activation Energy ◽  
Coke Formation ◽  
Tubular Reactor ◽  
Frequency Factor ◽  
Order Reaction ◽  
The Other ◽  
First Order ◽  
Consecutive Reactions ◽  
Secondary Reactions ◽  
Kinetics Of

The kinetics of pyrolysis of methylcyclohexane was investigated from the viewpoint of coke formation in a steel tubular reactor (S/V = 6·65 cm-1) at 0·1 MPa, 700 to 820 °C and residence time 0·01 to 0·24 s. Decomposition of methylcyclohexane proceeds as a first order reaction with a frequency factor 6·31 . 1015 s-1 and activation energy 251·2 kJ mol-1. The course of secondary reactions associated with the formation of coke is discussed. Investigation of coke formation showed a greater tendency of methylcyclohexane to coking in comparison with heptane. A prominent role plays the course of dehydrogenation of cycloalkane radicals up to aromates, this being reflected by the overall conversion of methylcyclohexane, and, on the other hand the thus formed aromates enter the consecutive reactions leading to coke.

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