Search results for "N alkanes"
showing 6 items of 6 documents
Qualitative and quantitative analysis of the n-alkanes C9-C17 and pristane in clean air masses
1980
An analytical method was developed for measuring n-alkanes (C9 to C17) and other hydrocarbons in tropospheric air with mixing ratios of a few ppt (10−12) and higher. The hydrocarbons are collected in situ in absorption tubes, carefully protected against contamination and analysed later in the laboratory by gas chromatography. First data are reported for Atlantic air masses at the west coast of Ireland.
Size-activity relationship of iridium particles supported on silica for the total oxidation of volatile organic compounds (VOCs)
2019
12 Figures, 2 Tables.-- Datos suplementarios disponibles en línea en la página web del editor.-- © 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
Effect of an Insect Growth Regulator (Halofenozide) on the Cuticular Hydrocarbons ofCulex pipiensLarvae
2013
The cuticular hydrocarbons of the fourth-instar larvae of Culex pipiens aged one and six days were analysed by gas chromatography and gas chromatography-mass spectrometry. The effect of an insect growth regulator (halofenozide = RH-0345) on the cuticular hydrocarbons was evaluated using newly moulted fourth-instar larvae of C. pipiens, at the lethal concentrations (LC50 = 12.58 and LC90 = 28.58 µ/l). A previous study revealed that RH-0345 is toxic to larvae of C. pipiens by induction of precocious larval moulting. Several cuticular hydrocarbons (CHCs) were identified and many of the other compounds remained unknown. Our data show that the CHC classes consisted of n-alkanes (C23-C29) and dif…
Pressure induced changes in the Raman spectra of liquidn-alkanes and perfluoro-n-alkanes
1982
The main effect of pressures up to 6 kbar on the Raman spectra of liquidn-alkanes and perfluoro-n-alkanes is a reduction of line widths indicative for a slowing-down of rotational motions about the long axes. There is no evidence for a change in the conformer populations.
A raman spectroscopic determination of the interlamellar forces in crystalline n-alkanes and of the limiting elastic modulus Ec of polyethylene
1976
A simple treatment based on continuum mechanics shows that weak interlamellar forces in crystalline n-alkanes should result in a characteristic upward shift of the frequencies of the longitudinal acoustical (LA) modes, which is independent of the chain length and decreases inversely with the mode order. A raman spectroscopic determination of the LA mode frequencies of a series of different n-alkanes confirms the theoretical conclusion and permits a derivation of a force constant characteristic of the interlamellar forces. The discussion results in a new formula valid for the LA mode frequencies of the orthorhombic n-alkanes in the acoustical limit and yields a new determination of the limit…
Stabilization of ZSM-5 zeolite catalysts for steam catalytic cracking of naphtha for production of propene and ethene
2012
In order to increase ethene and propene, naphtha steam catalytic cracking has been considered. The cracking of C 5-C 12 n-alkanes with ZSM-5 has been studied in absence and in presence of steam and the influence of the operation variables was studied. Irreversible catalyst deactivation by dealumination also occurs in the reactor when the cracking is carried out in the presence of steam. To diminish steam deactivation, the influence of zeolite Si/Al framework and a postsynthesis treatment by phosphorous have been studied and optimized. Much more stable catalyst can be achieved that result in an increase in activity without penalty for production of ethene and propene.