Introduction methods as in investigating the gasoline fractions.
In this case, however, we encounter very great The composition and properties of petroleum difficulties linked with the complex composition fractions constitute a major scientific problem, of the hydrocarbon mixtures under examination. whose study is of great importance both for oil Apart from numerous monocyclic hydrocarrefining and for settling the question of the origin bons, polycyclic systems composed of fused and of oil. The petroleum fractions studied most fully unfused six- and five-membered rings may also at present are those boiling out below 2000. (* *) be present in naphtha and kerosene fractions (in The composition of the higher boiling fractions some cases their presence has in fact been estabhas been studied insufficiently, owing to its exlished). traordinary complexity and the inadequacy of To synthesize even the basic hydrocarbons the methods of investigation. of these types is a task of considerable dificulty, Modern methods of investigation make it posand only initial headway has been made in this sible to study the individual composition of field. Only naphthalene hydrocarbons have been gasoline fractions by various physical, physicostudied closely, and in the kerosene fractions it chemical and chemical means, as well as by using is these hydrocarbons that have been subjected the adsorption separation of hydrocarbons into t o the closest examination. groups, the dehydrogenation catalysis of six-In higher fractions, owing to their complexity, membered naphthenic rings, and precise rectification in high-efficiency columns. The subse- the identification of individual hydrocarbons is a matter of great difficulty quent identification of the hydrocarbons is ac-; so the feasible line complished by spectral methods (Raman spectra, of development here is to study hydrocarbon types absorption analysis in various spectral regions) chiefly by methods of molecular spectroscopy. and mass spectrometric analysis. Lately, ultra-violet and infra-red absorptive These methods make it possible to achieve spectroscopy has proved to be a considerable the almost complete identification of the hydro- asset in the identification of kerosene fractions. carbons of the gasoline fractions of oil boiling be- However, a number of typical hydrocarbons, low 1600 (F. D. Rossini, B. A. Kazansky and G. which may be present in kerosene and higher S. Landsberg, A. V. Topchiev and others). fractions, cannot as yet be identified because of The results attained in the study of the hy- the absence of the spectral characteristics of pure drocarbon composition of gasoline fractions are to individual hydrocarbons. a large measure due to the possibility of synthe- The absence of reliable chemical and physisizing practically all the various typ
