H and 13C Nuclear Magnetic Resonance (NMR) spectrometric techniques for the determination of a series of parameters whlch describe the average molecular structure of coll-derived liquids are presented. The methods are adaptations of establlshed technlques for aromatic fractions of petroleum. Average molecular structure parameters for six coal-derived llqulds are reported, and differences among the six samples are Interpreted.Recent work in the development of alternate fuels technology has created a need for additional analytical methodology. Techniques for characterization of petroleum and petroleum derivatives have been developed over a 30-year period. Equivalent techniques for coal-derived liquids must now be devised. The development of suitable methods is simplified if experience gained in petroleum analysis can be applied to the new problems.Coal-derived liquids are extremely complex mixtures, often containing hundreds or thousands of components ( I ) . Highly aromatic condensed-ring structures predominate ( I , 2). Individual quantitation of each component is conceptually possible, but may be too detailed and time consuming for routine guidance of process development. An alternative approach involves characterization in terms of selected average properties of the sample. Such an analysis gives an easily interpreted picture of the sample, and yet contains significant quantitative information.Recent work on coal-derived liquids has resulted in NMR methods for the separate determination of C/H ratios for the aromatic and alkyl carbons of the sample (3, 4), and for measurement of the ratio of aromatic to alkyl carbon (5,6), qualitative descriptions of coal liquid fractions have also been made (7). The approach taken in the current study is to use analytical data to calculate a series of parameters which describe an average molecule in the sample. This technique has been well developed for characterization of aromatic fractions of petroleum (&IO), and is readily adapted to coal-derived liquids.Williams (8), using only lH NMR, originally defined the average molecular structure parameters shown in Table I. The method was extended and improved when Knight (9) applied 13C NMR to the problem. The nomenclature used in Table I is largely taken from a paper by Clutter et al. (IO).The relatively high concentrations of fused-ring structures in coal-derived liquids means that some care must be taken in the interpretation of the parameters. For instance, the compound tetralin is considered to have two branches of two carbons each. Also, the calculations do not distinguish between saturate rings fused to aromatic rings, as in tetralin, and naphthene rings substituted on aromatic rings, as in cyclohexyl benzene. Thus the parameter RN was originally defined as the number of naphthene rings per average molecule (&IO), but, for coal liquids, is better defined as the Table I. Average Molecular Structure Parameters: Definitions C = Weight fraction of carbon H = Weight fraction of hydrogen MW = Average molecular weight fa = Fraction...

Polarization scrambling by high pressure cell windows as a function of pressure up to 2 kbar has been measured for two window materials and two sizes of plug apertures. Measured scrambling was about 1% for quartz, 0.5% for float glass, and decreased with decreasing aperture size. The amount of scrambling decreased significantly with time when the cell was left pressurized. A qualitative explanation of the results, based on changes in the P44 Pockets coefficient with pressure is given.

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