Determination du diagramme de phases du systéme docosane (n-C22)-tétracosane (n-C24): variation de fenthalpie des mélanges en fonction de la température

New insights on the crystalline forms in binary systems of n-alkanes: Characterization of the solid ordered phases in the phase diagram tricosane + pentacosane

“…Indeed, experimental results on this system and on other binary systems and, in particular, on C 26 1 C 28 (the subject of another paper) have enabled us to characterize for the first time the three intermediate forms and to propose, therefore, a new phase diagram for the binary system C 23 -C 25 . The scope of this work is even wider since these phases are also observed in other binary systems [31][32][33][34][35][36][37][38][39][40][41] of n-alkanes [with a chain-length difference ͑Dn͒ equal to 1 or 2]. In other words, this paper leads to a complete characterization of all solid ordered forms observed in all binary systems of n-alkanes (the components belonging to the range C 16 to C 28 ).…”

“…The study of binary phase diagrams (temperature versus composition) has revealed a complex structural behavior of the mixed samples [28][29][30][31][32][33][34][35][36][37][38][39][40][41] where other forms than those seen in the components are observed and which are stabilized by mixing. The earliest binary phase diagram showing multiple one-phase domains at low temperature (temperature domain where the ordered phases are observed) is that of Lüth et al 28 for the system C 20 -C 22 .…”

“…Polymorphism of n-alkanes (C n H 2n12 ; hereafter denoted by C n ) and determination of binary phase diagrams [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] in the alkane family have been reported on in recent years in numerous publications. The polymorphism of n-alkanes is rather well known where many solid-solid phase transitions have been observed as a function of temperature.…”

Normal Alkanes, Multialkane Synthetic Model Mixtures, and Real Petroleum Waxes: Crystallographic Structures, Thermodynamic Properties, and Crystallization

“…26,55,65,133,237,256,257 Many phase diagrams have been presented with an orthorhombic continuous solid solution at room temperature even if the two pure C n 's displayed a (n c -n c′ )/n c relative gap between the chain lengths of molecules which was too high, according to Kravchenko's rule (Table 6), and/or a triclinic or monoclinic phase not compatible with Palatnik 170 (C 24 /C 28 ). 194 In 1974, Lu ¨th et al 145 Then Hasnaoui et al 65 also highlighted three orthorhombic intermediate phases in the (C 22 /C 24 ) system; Achour et al 149,150,152 showed the similarity between the (C 20 /C 22 ) phase diagram of Lu ¨th et al 65 and those of both of the (C 22 / C 24 ) 149,150,152 and (C 24 /C 26 ) systems determined by Achour-Boudjema et al 154,157 At the same time, Gerson and Nyburg 24 determined the structure of one of these intermediate phases of the C 24 /C 26 system: orthorhombic space group Bb2 1 m From the structural observations of Smith 143 and Gerson and Nyburg 26 and the phase diagrams determined by Lu ¨th et al 145 (C 20 /C 22 ), by Achour et al 149,150 (C 22 /C 24 and C 24 / C 26 ), 154,157 by Denicolo et al 168 and Nouar et al 165 (i) At room temperature, limited terminal solid solutions with the pure C n crystalline structure exist for the concentrations close to two pure C n 's, and two (∆n c ) 1) or three orthorhombic intermediate solid solutions (∆n c ) 2) appear when the concentration varies; these intermediate phases are respectively denoted β′ 1or2 and β′′ 1or2 . In all the binary systems, the β′ phases are indistinguishable and thus they are isostructural.…”

Temperatures and Enthalpies of Solid−Solid and Melting Transitions of the Odd-Numbered n-Alkanes C21, C23, C25, C27, and C29

“…Because of the importance of the n-paraffins in petroleum technology, numerous studies have been carried out to determine the thermodynamic data of pure n-alkanes (hereafter denoted by C n ) (Achour et al, 1981;Andon et al, 1976;Atkinson et al, 1969;Barbillon et al, 1991;Bonsor et al, 1997;Broadhurst, 1962;Domalski et al, 1990;Domanska et al, 1999;Doucet et al, 1981;Doucet et al, 1984;Dreisbach, 1959;Fredricks, 1986;Hasnoui et al, 1998;Heyding et al, 1990;Hoffman et al, 1953;Jin et al, 1991;Josefiak et al, 1977;Lourdin, 1991;Maroncelli et al, 1982;Mazee, 1948;Mazee, 1949;Messerly et al, 1967;Parks et al, 1929;Parks et al, 1930;Robles et al, 1998;Schaerer et al, 1955;Schmidt et al, 1941;Seyer et al, 1944;Sirota et al, 1993;Snyder et al, 1981;Ungar, 1983) and their binary mixtures (Achour et al, 1981;Achour et al, 1992;Achour-Boudjema et al, 1996;Doucet et al, 1984;Ghogomu et al, 1997;Jouti et al, 1996;Nouar et al, 1997;Oonk et al, 1998;Robles et al, 1996;…”