Figure 1
Stites & Associates, LLC, has developed a GC/MS method for characterizing retorted oil from oil shale. The main purpose is to track characteristics like mono- and di-olefins, nitrogen and oxygen containing compounds and substituted aromatic compounds. These are important not only for general oil quality, but especially oil stability and reactivity. These compounds are notorious for polymerizing over time causing downstream problems for fuel applications. On the other hand, controlled chain growth can give very beneficial results in other oil applications.
In Figure 1 above we see a typical retort oil across the broad spectrum of compounds that are found in the oil. Not easily seen are a series of doublets including straight chain paraffins and the corresponding terminal olefin. This is shown more clearly in Figure 2, a smaller portion of the chromatogram.
Figure 2
An expansion of the chromatogram around 13 minutes clearly shows the doublet of 1-tridecene and n-tridecane. The doublet TIC is shown in Figure 3 while Figures 4 and 5 show the mass spectra of n-tridecane and 1-tridecene respectively.
Figure 3
Figure 4
Figure 5
By measuring the ratios of alkanes to their related 1-alkenes the general reactivity of the retort oil can be tracked. The results of a variety of changing retort conditions can be monitored to tailor the oil to desired properties.
More work is being done in the area of nitrogen, oxygen and aromatic compounds. These are more complex and their impacts less obvious. Work is continuing in this are as SALLC continues to support the oil shale industry. Similar detailed analysis of other oils can also give insight into a wide variety of physical and chemical properties.
Stites & Associates, LLC, is a group of technical professionals who work with clients to improve laboratory performance and evaluate and improve technology by applying good management judgment based on objective evidence and sound scientific thinking. For more information see: www.tek-dev.net.
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