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The Chemistry and Technology of Petroleum
of the corresponding Engler profile (ASTM D86) as well as the prediction of other properties, such
as vapor pressure and flash point.
Simulated distillation by gas chromatography is applied in the petrochemical industry to obtain true
boiling point distributions of distillates and crude oils. Two standardized methods, ASTM D2887 and
D3710, are available for the boiling point determination of petroleum fractions and gasoline, respectively.
The ASTM D2887 method utilizes nonpolar, packed gas chromatographic columns in conjunction with
flame ionization detection. The upper limit of the boiling range covered by this method is to approximately 540°C (1000°F) atmospheric equivalent boiling point. Recent efforts in which high- temperature
gas chromatography was used have focused on extending the scope of the ASTM D2887 methods for
higher boiling petroleum materials to 800°C (1470°F) atmospheric equivalent boiling point.
10.8.3 AdsorPtIon CHromAtogrAPHy
Adsorption chromatography has helped to characterize the group composition of crude oils and
hydrocarbon products since the beginning of this century.
The type and relative amount of certain hydrocarbon classes in the matrix can have a profound effect
on the quality and performance of the hydrocarbon product and two standard test methods have been
used predominantly over the years (ASTM D2007, ASTM D4124). The fluorescent indicator adsorption
(FIA) method (ASTM D1319) has served for over 30 years as the official method of the petroleum industry for measuring the paraffinic, olefinic, and aromatic content of gasoline and jet fuel. The technique
consists of displacing a sample under iso-propanol pressure through a column packed with silica gel in
the presence of fluorescent indicators specific to each hydrocarbon family. Despite its widespread use,
FIA has numerous limitations (Suatoni and Garber, 1975; Miller et al., 1983; Norris and Rawdon, 1984).
The segregation of individual components from a mixture can be achieved by application of adsorption chromatography in which the adsorbent is either packed in an open tube (column chromatography)
or shaped in the form of a sheet (thin-layer chromatography, TLC). A suitable solvent is used to elute
from the bed of the adsorbent. Chromatographic separations are usually performed for the purpose of
determining the composition of a sample. Even with such complex samples as petroleum, some information about the chemical structure of a fraction can be gained from the separation data (Chapter 9).
In the present context, the challenge is the nature of the heteroatomic species in the heavier
feedstocks. It is these constituents that are largely responsible for coke formation and catalyst deactivation during refining operations. Therefore, it is these constituents that are the focus of much of
the study. An ideal integrated separation scheme for the analysis of the heteroatomic constituents
should therefore meet several criteria:
1. The various compound types should be concentrated into a reasonable number of discrete
fractions, and each fraction should contain specific types of the heteroatomic compounds.
It is also necessary that most of the heterocompounds be separated from the hydrocarbons
and sulfur compounds that may constitute the bulk of the sample.
2. Perhaps most important, the separation should be reproducible insofar as the yields of the
various fractions and the distribution of the compound types among the fractions should
be constant within the limits of experimental error.
3. The separation scheme should be applicable to high-boiling distillates and heavy feedstocks
such as residua since heteroatomic compounds often predominate in these feedstocks.
4. The separation procedures should be relatively simple to perform and free of complexity.
5. Finally, the overall separation procedure should yield quantitative or, at worst, near quantitative recovery of the various heteroatomic species present in the feedstock. There should be
no significant loss of these species to the adsorbent or, perhaps more important, any chemical alteration of these compounds. Should chemical alteration occur, it will give misleading
data that could have serious effects on refining predictions or on geochemical observations.
The Chemistry and Technology of Petroleum
of the corresponding Engler profile (ASTM D86) as well as the prediction of other properties, such
as vapor pressure and flash point.
Simulated distillation by gas chromatography is applied in the petrochemical industry to obtain true
boiling point distributions of distillates and crude oils. Two standardized methods, ASTM D2887 and
D3710, are available for the boiling point determination of petroleum fractions and gasoline, respectively.
The ASTM D2887 method utilizes nonpolar, packed gas chromatographic columns in conjunction with
flame ionization detection. The upper limit of the boiling range covered by this method is to approximately 540°C (1000°F) atmospheric equivalent boiling point. Recent efforts in which high- temperature
gas chromatography was used have focused on extending the scope of the ASTM D2887 methods for
higher boiling petroleum materials to 800°C (1470°F) atmospheric equivalent boiling point.
10.8.3 AdsorPtIon CHromAtogrAPHy
Adsorption chromatography has helped to characterize the group composition of crude oils and
hydrocarbon products since the beginning of this century.
The type and relative amount of certain hydrocarbon classes in the matrix can have a profound effect
on the quality and performance of the hydrocarbon product and two standard test methods have been
used predominantly over the years (ASTM D2007, ASTM D4124). The fluorescent indicator adsorption
(FIA) method (ASTM D1319) has served for over 30 years as the official method of the petroleum industry for measuring the paraffinic, olefinic, and aromatic content of gasoline and jet fuel. The technique
consists of displacing a sample under iso-propanol pressure through a column packed with silica gel in
the presence of fluorescent indicators specific to each hydrocarbon family. Despite its widespread use,
FIA has numerous limitations (Suatoni and Garber, 1975; Miller et al., 1983; Norris and Rawdon, 1984).
The segregation of individual components from a mixture can be achieved by application of adsorption chromatography in which the adsorbent is either packed in an open tube (column chromatography)
or shaped in the form of a sheet (thin-layer chromatography, TLC). A suitable solvent is used to elute
from the bed of the adsorbent. Chromatographic separations are usually performed for the purpose of
determining the composition of a sample. Even with such complex samples as petroleum, some information about the chemical structure of a fraction can be gained from the separation data (Chapter 9).
In the present context, the challenge is the nature of the heteroatomic species in the heavier
feedstocks. It is these constituents that are largely responsible for coke formation and catalyst deactivation during refining operations. Therefore, it is these constituents that are the focus of much of
the study. An ideal integrated separation scheme for the analysis of the heteroatomic constituents
should therefore meet several criteria:
1. The various compound types should be concentrated into a reasonable number of discrete
fractions, and each fraction should contain specific types of the heteroatomic compounds.
It is also necessary that most of the heterocompounds be separated from the hydrocarbons
and sulfur compounds that may constitute the bulk of the sample.
2. Perhaps most important, the separation should be reproducible insofar as the yields of the
various fractions and the distribution of the compound types among the fractions should
be constant within the limits of experimental error.
3. The separation scheme should be applicable to high-boiling distillates and heavy feedstocks
such as residua since heteroatomic compounds often predominate in these feedstocks.
4. The separation procedures should be relatively simple to perform and free of complexity.
5. Finally, the overall separation procedure should yield quantitative or, at worst, near quantitative recovery of the various heteroatomic species present in the feedstock. There should be
no significant loss of these species to the adsorbent or, perhaps more important, any chemical alteration of these compounds. Should chemical alteration occur, it will give misleading
data that could have serious effects on refining predictions or on geochemical observations.