STUDY OF THE TEMPERATURE AND ENTHALPY OF THERMALLY INDUCED PHASE-TRANSITIONS IN n-ALKANES, THEIR MIXTURES AND FISCHER-TROPSCH WAXES

Srivastava, S. P.; Butz, T.; Oschmann, Hans-Jörg; Rahimian, I.

doi:10.1080/10916460008949857

Cited by 13 publications

(9 citation statements)

References 15 publications

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“…Achour et al 186,187 and Jouti et al 188 6), the binary phase diagram displays partial miscibility or no miscibility with eutectic 55,181,189,190,232,256,257 or peritectic 192 solidification, as forseen by Turner. 53 (2) Ternary, Quaternary, and Quinary Systems.…”

Section: ) Binary Mixtures Of Consecutive C N 'S (∆N C E 2)mentioning

confidence: 87%

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

Dirand¹,

Bouroukba²,

Chevallier³

et al. 2002

J. Chem. Eng. Data

212

335

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A general review is presented concerning jointly the crystallographic structures and the solid-solid and solid-liquid transition temperatures and enthalpies in the pure normal alkanes, as well as the structural and thermodynamic behavior of their synthetic binary, ternary, and multinary model mixtures and of real petroleum waxes. A major part of the structural and thermodynamic data of the literature, relative to the pure n-alkanes, are listed from methane up to the alkane with carbon atom number equal to 390. Variation relationships of the crystallographic long c-parameter that corresponds to the periodicity of the molecule layer packing along their axis, melting temperatures, and transition enthalpies are given as a function of the carbon atom number. The study of the literature on the n-alkane mixtures highlights the existence of isostructural binary, ternary, and multinary intermediate solid solutions which can be likened to a single pseudocomponent. This intermediate solid solution is equivalent to a hypothetical pure n-alkane whose carbon atom number is equal to the average carbon atom number of the mixtures. As a result, the solubility of these multinary solid solutions or real multiparaffinic waxes in linear, cyclic, or aromatic light solvents is identical to that of the pure n-alkanes: pseudobinary eutectic crystallization of the model or real wax as a single pseudocomponent on one hand and the light solvent on the other hand.

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Section: ) Binary Mixtures Of Consecutive C N 'S (∆N C E 2)mentioning

confidence: 87%

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

Dirand¹,

Bouroukba²,

Chevallier³

et al. 2002

J. Chem. Eng. Data

212

335

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“…Because of the importance of the n -alkanes (hereafter denoted by C n ), numerous studies − have been carried out to determine their thermodynamic properties and their structural behavior. Although numerous values of the temperatures and enthalpies of solid−solid and solid−liquid transitions of C n 's are available ...…”

Section: Introductionmentioning

confidence: 99%

Experimental Enthalpy Increments from the Solid Phases to the Liquid Phase of Homologous n-Alkane Series (C₁₈ to C₃₈ and C₄₁, C₄₄, C₄₆, C₅₀, C₅₄, and C₆₀)

Briard¹,

Bouroukba²,

Petitjean³

et al. 2003

J. Chem. Eng. Data

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Measurements of enthalpy increments from the temperature of the ordered phases of low temperatures at 293.4 K and 298.3 K up to the liquid phase above the melting point were carried out by differential scanning calorimetry using a discontinuous mode of temperature programming on the n-alkanes from C 18 to C 38 and C 41 , C 44 , C 46 , C 50 , C 54 , and C 60 . The temperatures and enthalpies of the solid-solid transitions and of the fusion were also determined and compared with the values of the literature.

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“…Since aliphatic hydrocarbons are able to fit into a similar crystal lattice, the same process could occur in the wax of bitumen . With a faster growth rate, the shorter chains are trapped by the fast crystallization of the longer chains, which results in a solid solution formation. , The presence of another hydrocarbon facilitates the formation of the solid solution. , Thus, fast cooling in the bitumen results in the metastable dispersion of small, imperfect wax crystals suspended in the liquid oil phase. , …”

Section: Resultsmentioning

confidence: 99%

“…39,49 The presence of another hydrocarbon facilitates the formation of the solid solution. 50,51 Thus, fast cooling in the bitumen results in the metastable dispersion of small, imperfect wax crystals suspended in the liquid oil phase. 13,27 There are two types of crystallization: primary, where the sizes of the formed crystallites are mainly a function of the supercooling degree, and secondary, where crystallization needs no supercooling and is caused by growth on existing nuclei.…”

Section: Resultsmentioning

confidence: 99%

Interpretation of Double-Peak Endotherm on DSC Heating Curves of Bitumen

et al. 2020

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Since the late 1960s, differential scanning calorimetry (DSC) has been used to characterize petroleum bitumen, in particular, for the determination of the crystallized fraction (CF) content. This procedure is based on the construction of a baseline after identifying the CF dissolution endotherm on the heating curve. However, many bitumens commonly exhibit double-peak endotherms during a DSC heating scan. In this case, the task of constructing the corresponding baseline does not have a unique solution because the interpretation of the heat flow profile is ambiguous. Several interpretations have been proposed earlier to explain the origins of the double-peak endotherm. However, the double-peak endotherm is currently still not fully understood, and a comprehensive consensus has not been achieved. If the determination of the baseline location is incorrect, the CF content can be over- or underestimated by 20–30%. In the current work, double-peak endotherm behavior was investigated by temperature modulation DSC. All of the earlier explanations were critically considered. The origin of the double-peak endotherm was discussed in detail, and a probable descriptive model for the formation of the double-peak endotherm was suggested. The endotherm pattern is assumed to be governed by three overlapping thermal events: a broad endothermic background and a twin “recrystallization exotherm–dissolution endotherm” pair. The onset of the recrystallization exotherm and the intensity of both events depend on the annealing temperature and time. The study promotes a better understanding of the relationship between the thermal effects on the DSC curves and the structural changes of bitumen. A correct interpretation of the double-peak endotherm can provide a more exact determination of the CF content in bitumen.

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STUDY OF THE TEMPERATURE AND ENTHALPY OF THERMALLY INDUCED PHASE-TRANSITIONS IN n-ALKANES, THEIR MIXTURES AND FISCHER-TROPSCH WAXES

Cited by 13 publications

References 15 publications

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

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

Experimental Enthalpy Increments from the Solid Phases to the Liquid Phase of Homologous n-Alkane Series (C₁₈ to C₃₈ and C₄₁, C₄₄, C₄₆, C₅₀, C₅₄, and C₆₀)

Interpretation of Double-Peak Endotherm on DSC Heating Curves of Bitumen

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STUDY OF THE TEMPERATURE AND ENTHALPY OF THERMALLY INDUCED PHASE-TRANSITIONS IN n-ALKANES, THEIR MIXTURES AND FISCHER-TROPSCH WAXES

Cited by 13 publications

References 15 publications

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

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

Experimental Enthalpy Increments from the Solid Phases to the Liquid Phase of Homologous n-Alkane Series (C18 to C38 and C41, C44, C46, C50, C54, and C60)

Interpretation of Double-Peak Endotherm on DSC Heating Curves of Bitumen

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Experimental Enthalpy Increments from the Solid Phases to the Liquid Phase of Homologous n-Alkane Series (C₁₈ to C₃₈ and C₄₁, C₄₄, C₄₆, C₅₀, C₅₄, and C₆₀)