Hydrocarbon type analysis

Hydrocarbon composition is also determined by mass spectrometry, a technique that has seen wide use for hydrocarbon-type analysis of naphtha and gasoline (ASTM D2789) as well as for the identification of hydrocarbon constituents in higher-boiling naphtha fractions (ASTM D2425). 

Table VI. Hydrocarbon-Type Analysis of Debutanized Pennsylvania Straight-Run Gasoline, Platformate, and Thermal Reformate...

The hydrocarbon-type analysis of the Platformate discussed above was based on the product having an octane number of 92.9 (F-l plus 3 ml. of tetraethyllead per gallon). The aromatic content (based on charge) increases continually with increased severity. At the two highest severities, the aromatic yield (based on the charge) is in excess of the total naphthenes and aromatics present in the charge. This indicates the participation of the dehydrocyclization reaction of paraffins to form aromatics. 

Lanning, W. C. Green, J. B. Dooley, J. E. The Preparation of Liquids from Coals for Hydrocarbon-Type Analysis in Relation to Refining. DOE/BETC/RI-78/10, 1978, 27 pp. 

The classical silica gel chromatographic method for determination of percent olefins in shale oils was studied and found wanting, mainly because of cross-contamination from high levels of olefins and heteroatom-containing compounds. This paper describes a new hydroboration/oxidation procedure for olefins, and reports its use in hydrocarbon-type analysis of both whole shale oils and distillate fractions. Percent composition values for three whole oils ranged as follows saturates, 13-26 olefins, 16-20 aromatics, 5-14 polar compounds, 41S2. A discussion of IR analysis for relative amounts of specific olefin types such as terminal, internal trans, and methylene structures is included. 

Work in the area of hydrocarbon-type analysis, i.e. saturate, olefin, and aromatic, has been conducted at the Laramie Energy Research Center (LERC) for over two decades. During this time, a significant portion of the eflFort has been directed towards the quantification and characterization of the various types of olefins found in Green River Formation shale oils and their distillate fractions (1-9). 

This chapter presents a close look at the standard silica gel analysis of a shale oil naphtha with an evaluation of its effectiveness, a description of the new method now used to quantify olefins in shale oil products, a summary of results of the hydrocarbon-type analysis using the new method for a series of three related shale oils, and a discussion of the information on olefin-type compounds which can be revealed by IR examination of whole shale oils. The paper concludes with a brief discussion of additional applications of the hydroboration of olefins to problems of interest to the petroleum analyst. 

As with all shale oils, the polar material first must be removed from the oil prior to hydrocarbon-type analysis. The procedure shown in Figure 1 was applied several years ago to shale oil distillates in the boiling ranges 200°-325°C and 325°-S00°C (9). The technique made use of added internal standards and GC comparison of sample-internal... 

Table I. Hydrocarbon-Type Analysis of Shale Oil Distillates...

GEOSECS surface samples show a n-paraflBn distribution with a maximum at C28 which is significantly different from the C23 maximum observed for the envelope. The hydrocarbons under the envelope are a complex mixture as shown by the hydrocarbon type analysis. 

Compositional analysis of kerosene distillates can also be obtained in terms of mass spectral Z-series (ASTM D-2425, ASTM D-2789, ASTM D-3239, ASTM D-6379). Mass spectrometry has been a powerful technique for hydrocarbon type analysis of middle distillates and can provide more compositional detail than chromatographic analysis. Hydrocarbon types are classified in terms of a Z-series. Z in the empirical formula C H2 +z is a... 

Aromatics, % Hydrocarbon type analysis CA, % Hydrocarbon type analysis ASTM D2007 ASTM D2140 ASTM D3238 4 ... 

J. G. O Connor and M. S. Norris, Molecular Sieve Adsorption, Application to Hydrocarbon Type Analysis, Analytical Chemistry 32 701-706 (1960). 

Barman, B.N. Hydrocarbon-type analysis of base oils and other heavy distillates by thin-layer chromatography with flame-ionization detection and hy the clay-gel method. J. Chromatogr. Sci. 1996, 34 (5), 219-225. 

Coal liquids consist of hundreds of individual components and therefore, it is very difficult to identify all the individual components in a sample. The components can be classified as different types such as paraffins, naph-thenics, and aromatics. Because of an MS ability to identify compound-type unique molecular ion fragment patterns, hydrocarbon-type analysis by MS has been practiced for over four decades. ASTM D-2425 specifies a standard test method for hydrocarbon types in middle distillates by MS, with a boiling range of 20 343°C. This is within the boiling range of many CTL process products, so GC-MS has been used for hydrocarbon-type analysis in coal liquids. Initial product separations are conventionally needed for GC-MS-type analysis, such as distillation (ASTM D-86), elution chromatography. 

FIGURE 13.25 Chromatogram from hydrocarbon type analysis of gasoline. (Reprinted with permission from Reference 80, Journal of Chromatographic Science, Cop3right 1971, E eston Publications, A Division of Preston Indnstries, Inc.)... 

---