A Small Angle X-Ray Scattering Study of the Colloidal Nature of Petroleum

Dwiggins, C. W.

doi:10.1021/j100894a041

Cited by 54 publications

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“…Even though the lower limit of scattering angle 20 is 100" in comparison to a lower limit of over 600" in earlier work (Dwiggins, 1965), no new information was obtained for this specimen. It should be noted that the radius ofgyration obtained is slightly lower than that reported for a different sample of Tia Juana oil (Dwiggins, 1965). It is not uncommon for different samples of oil from a large oil field to be somewhat different in several properties.…”

Section: Results and Discussion For Addition Of Hydrocarbons And Alcocontrasting

confidence: 73%

“…Earlier studies (Dwiggins, 1965) indicated that assuming particles scatter independently is reasonable when one is working with crude oils and diluted crude oils.…”

Section: Results and Discussion For Addition Of Hydrocarbons And Alcomentioning

confidence: 99%

“…Collimation corrections were not made, because in previous work (Dwiggins, 1965) they were found to be unnecessary for obtaining radii of gyration of crude-oil colloids. However, slit-length corrections would be necessary for determination of some parameters that are not of interest to this study.…”

Section: Automated Instrument Control and Data Reductionmentioning

confidence: 99%

“…Previous small-angle X-ray scattering studies (Dwiggins, 1965) indicated that many crude oils contain colloids rich in asphaltic material, that the size of the colloids can be determined, and that some information about polydispersity can be obtained. Earlier references are given in that paper.…”

Section: Introductionmentioning

confidence: 99%

“…The second objective was to study the effect of adding various types of hydrocarbons and alcohols to crude oil, because some hydrocarbons produce colloid growth (Dwiggins, 1965).…”

Section: Introductionmentioning

confidence: 99%

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Study of colloidal nature of petroleum with an automated Bonse–Hart X-ray small-angle scattering unit

Dwiggins¹

1978

J Appl Cryst

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615was the possible occurrence of a spinodal mode of decomposition.The above quenched compositions were aged at temperatures from 200 to 850°C and the small-angle spectra were followed isothermally. To a first approximation spinodal behavior was observed for a number of compositions and temperatures (e.g. for 30 mol% A120 3 at 200 and 600°C), though the mode of decomposition could not with certainty be specified as linear. There was, however, indication of a non-shifting cross-over point and an increasing integrated intensity for the SANS experiments, which indicates that a spinodal process is occurring. For example, an examination of the R(fl)-vs-fl plot for 30 mol% AI20 3 for the 0-5 min interval of aging at 200 °C gives tic~tim = 2-68 and 2,. = 175 ,~, indicating that this composition is within the spinodal region at 200 ° C. On the other hand, aging at 850°C for only 1 and 5 min showed a clear decay in the scattering curves, indicating that the glass was homogenizing. A new miscibility gap was, thus, constructed from the region of the experimentally determined spinodal line.The large observed SAXS scattering noted for this system is an indication that considerable changes of density are occurring concurrently with decomposition (Si and AI have closely similar atomic scattering factors, and, thus, are not expected to yield a strong SAXS intensity). This was confirmed with density and refractive index measurements, which enabled us to conclude that the observed density fluctuations, e.g. as observed by SAXS, result from alumina densification.Thus, density and composition fluctuations are one and the same. J. Appl. Cryst. (1978). 11, 615619Study of the Colloidal Nature of Petroleum with an Automated Bonse-Hart X-ray Small-Angle Scattering Unit A Bonse-Hart small-angle X-ray diffractometer was interfaced to an automated X-ray diffraction system and used to study the colloidal nature of crude oil. Asphaltic colloids, which have a radius ofgyration of 20 to 40A in many oils, were found to grow in size to several thousand A on addition of straight and branched-chain aliphatic hydrocarbons. Addition of cyclic and aromatic hydrocarbons produced little change in colloid size. Two types of large colloids, having radii of gyration of several hundred to several thousand A, were found in some crude oils in addition to the mentioned asphaltic ones. One of the larger colloids is wax. The other seems closely associated with the asphaltene colloids and is present in the asphaltene fraction on precipitation of the asphaltene with pentane. The use of ultracentrifugation, deasphalting, and temperature variation allowed mixtures of colloids to be studied in more detail than could be single oil samples.

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Section: Results and Discussion For Addition Of Hydrocarbons And Alcocontrasting

confidence: 73%

“…Earlier studies (Dwiggins, 1965) indicated that assuming particles scatter independently is reasonable when one is working with crude oils and diluted crude oils.…”

Section: Results and Discussion For Addition Of Hydrocarbons And Alcomentioning

confidence: 99%

Section: Automated Instrument Control and Data Reductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…The second objective was to study the effect of adding various types of hydrocarbons and alcohols to crude oil, because some hydrocarbons produce colloid growth (Dwiggins, 1965).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations