Mixtures of numerous different n-alkanes: 1. Structural studies by X-ray diffraction at room temperature—Correlation between the crystallographic long c parameter and the average composition of multi-alkane phases

Chevallier, Virginie; Provost, Élise; Bourdet, J.B.; Bouroukba, M.; Petitjean, D.; Dirand, M.

doi:10.1016/s0032-3861(98)00410-8

Cited by 72 publications

(80 citation statements)

References 55 publications

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“…(54)(55)(56)(57)(58)(59)(60)(61)(62)(63)(64)(65)(66) Using the experimental data it is possible to validate the different models, in which the solid phase precipitation is explained by one of the following hypotheses: crystallization of one multi-n-alkane solid solution, (67,68) or successive crystallizations of pure nalkanes. (32,69,70) Our experimental observations, (50)(51)(52)71) those of Craig et al, (12) and those of Flöter et al (60) agree with the first hypothesis, but the difficulty lies in finding an excess thermodynamic function for the representation of the solid behaviour. In this work, we investigate the phase diagram of n-hexacosane (C 26 ) and n-octacosane (C 28 ), in a range of compositions represented by the mean carbon number of paraffinic crude oil (n ≈ 27).…”

Section: Introductionsupporting

confidence: 73%

“…This solid solution, hereafter denoted β , has an orthorhombic structure, and is identical to the one already observed in many binary and ternary n-alkanes systems, (43)(44)(45)(46)(47)(48)(49)53) or in paraffinic crude oil. (50)(51)(52) .…”

Section: Resultsmentioning

confidence: 99%

“…In this paper, n-alkanes C n H 2n+2 are denoted by C n where n is the number of carbon atoms in the chain. In our laboratory, we are currently engaged in thermodynamic and structural studies of the liquid and solid phases of pure n-alkanes, (42) the (solid + liquid), and (solid + solid) equilibria in binary, (43)(44)(45)(46)(47)(48) ternary, (49) and multicomponent mixtures (50)(51)(52) of n-alkanes. Using the results already obtained, Dirand et al (53) highlighted a general behaviour of the thermodynamic and structural properties of consecutive binary n-alkanes (19 < n < 27), and deduced the following conclusion: existence of orthorhombic intermediate solid solutions, phenomenological laws for the succession of these intermediate phases when the composition varies, evolution of an intermediate solid solution with increase in temperature, the appearance of another orthorhombic phase, and rotator phases.…”

Section: Introductionmentioning

confidence: 99%

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Phase diagram ofn-hexacosane andn-octacosane: experimental determination and calculation

Provost¹,

Balesdent²,

Bouroukba³

et al. 1999

The Journal of Chemical Thermodynamics

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Section: Introductionsupporting

confidence: 73%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Phase diagram ofn-hexacosane andn-octacosane: experimental determination and calculation

Provost¹,

Balesdent²,

Bouroukba³

et al. 1999

The Journal of Chemical Thermodynamics

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“…Most authors, behind a generic label of 'solid', fail to clearly state the solid phase they are working with. The evidence today is that the alkyl chains in the wax adopt an orthorhombic structure [41][42][43][44][45] even if some isoalkanes or alkyl aromatic compounds are present as inclusions [46]. The correlations for thermophysical properties used are strongly associated to the solid phase adopted.…”

Section: Solid Phase and Thermophysical Propertiesmentioning

confidence: 99%

“…As discussed above and according to the experimental evidence [41][42][43][44][45] the model hereafter presented considers the wax formed by n-alkanes crystallising from a fluid as orthorhombic solid solutions [31][32]. The condition of equilibrium between the Liquid, Solid and Vapour phases is given by the equality of the fugacities in all phases for each individual component, i:…”

Section: Wax Formation Modelmentioning

confidence: 99%

Modelling Phase Equilibria in Systems with Organic Solid Solutions

Coutinho¹,

Pauly²,

Daridon³

2004

Computer Aided Chemical Engineering

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INTRODUCTIONThe formation of alloys of inorganic compounds has been known for centuries, yet it is not only on metallurgy and ceramics that metals and inorganic salts in general form mixed crystals. Reports on the formation of alloys, or solid solutions, of organic compounds, although still rare, have been appearing regularly in the last few years for aromatic compounds, such as substituted benzenes and naphtalenes [1][2][3], pyrene and anthracene [4][5][6], for carbohydrates [7], terpenes [8], neopentane derivatives [9-10] and fulerenes, besides solid solutions of C 60 with C 70 [11][12] solid solutions of C 60 in sulphur have been reported [13]. Nevertheless it is among the molecules with long n-alkyl chains such as n-alcohols Although the materials based on n-alkane alloys have been used for long as candles, waterproof coatings, pharmaceutical and cosmetics, and in spite of paraffin waxes being a valuable by-product of petroleum refining, the research on n-alkane solid solutions has been mainly prompted by its dark side: The damages and losses caused by wax precipitation from petroleum fluids. Every year wax deposition costs billions of dollars in preventive maintenance, remediation of pipeline blockages and losses of production [22,23]. Better computer models can help anticipate the problems allowing for preventive actions, optimization of actions and avoid losses by shutting down of production or by accident.The presentation of this chapter will focus on the prediction of the wax precipitation from petroleum fluids both at high pressures, in reservoir conditions, or at low pressures, as stock tank oil or fuels. In the final section the application of the model proposed to other systems of organic solid solutions will be discussed.

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