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    The Combination of Methods in the Analysis of Complex Hydrocarbon Systems

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    The last decade and a half has witnessed enormous strides in the technology of determining the composition of complex hydrocarbon systems. On the whole, the progress has been continuous and each year has seen important advances achieved and new areas penetrated. The complete problem is so vast that many techniques and many variations within techniques are employed. However, in looking back one can recognize three major landmarks of progress. These have been the advents of infrared spectroscopy, mass spectrometry, and, more recently, gas-liquid partition chromatography, respectively. It has been several years since the last of the major techniques came upon the scene. Nevertheless, the intense pace is continuing with significant progress in all important techniques in terms of instrumentation, a better understanding of the fundamental nature of the phenomena involved, and in empirical correlations. Parallel with this progress within techniques there has been a growing potential realizable by the combination of techniques for handling different aspects of major problems. The maximum utility of the different important techniques requires the services of professional specialists. The extensive utilization of various techniques on a teamwork approach to major problems therefore requires that a new degree of attention be applied to the segmentation of major problems and to effective technical coordination and communications. The vastness of the field of hydrocarbon analysis is a result of the thousands upon thousands of individual compounds that are inherently involved. It is well known that the number of possible isomers for any hydrocarbon class increases rapidly with the number of carbon atoms per molecule. This is displayed in Fig. 1, which gives the number of alkane isomers possible versus carbon number [11]. This extremely rapid rise effectively closes the door for comprehensive methods of analysis for specific compounds past the C7 or C8 range. The limitation is not so much a result of deficiencies in the techniques for resolving isomers as it is of the very high cost of synthesizing all the reference compounds. Another aspect is that a complete analysis of a C10 alkane cut, for example, involving information on each of the 75 isomers would not be very practical information to the process research or operations engineer. For other classes of hydrocarbons—olefins, for example— the number of possible isomers goes up even faster with carbon number.

    Author Information:

    Coggeshall, Norman D.
    Gulf Research and Development Co., Pittsburgh, Pa.

    Hubis, Walter
    Gulf Research and Development Co., Pittsburgh, Pa.

    Committee/Subcommittee: E13.01

    DOI: 10.1520/STP45785S