Shale olefin analysis

The classical silica gel olefin analysis was evaluated with respect to shale oil products and found wanting. A new approach to olefin analysis using mild, olefin-modifying reagents was described and partially demonstrated for shale oil distillates and whole oils. Hydrocarbon-type composition data and a discussion of IR analysis for various types of olefinic compounds were presented for three whole oils. 

Shale Oils. As indicated by the data in Table II, only cut I of the shale oils contains a considerable amount of material boiling below 470°F, as would be expected from the low boiling range of this fraction (Table V). This distillate was fractionated into saturates, aromatics, and olefins by preparative FIA techniques, but a GLC analysis of these fractions proved unfruitful for the same problems mentioned above for the coal liquids. 

Only the Big Horn coal liquids have more condensed cycloalkanes than noncondensed cycloalkanes. The tar sands have an equal distribution of the two types of saturates, and the remaining fuels have a higher concentration of noncondensed cycloalkanes. The effect of the olefins on the mass analysis of the saturates from the shale oils must, however, be kept in mind in making this comparison. 

What both the Chevron study and the SOHIO study indicate is that complete heteroatom removal from whole shale oil will require between 1,800 and 2,000 SCF of hydrogen per barrel of feedstock (13.55 kmol/m3 to 15.06 kmol/m3). What model compound analysis indicates is that hydrotreating of raw shale oil is rather selective, in that only about one-third of the hydrogen consumed is for olefin saturation, saturation of non-hetero aromatics, and hydrocracking. 

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. 

Olefins Aromatics. The hydroboration and analysis of shale oil distillate fractions have been described previously (9). Whole shale oils were prepared for determination of olefin and aromatic content by the removal of the polar material on Florisil (30/60 mesh, used as received) by elution with cyclohexane. The Florisil-to-oil weight ratio was 20/1 and the elution was carried out for 24 hr with a solvent recycle chromatography column. 

IR Analysis. IR absorption spectra were determined on neat samples of shale oils to furnish data for estimates of various olefinic types of compounds. Samples were run on a high-resolution, double-beam grating spectrophotometer at 0.1-mm path length between KBr plates. Quantitative measurements were made using the cut and weigh method with baselines drawn from point to point of minimum absorption. 

During analysis of some specific samples, such as shale-oil-derived distillates and products from FCC-MAT, we encountered high contents of olefinic compounds. The SAP method cannot provide separation of olefins. 

---