ALL petroleum-oil cracking operations that have been developed to meet the quantity demand for engine fuel are liquid-phase processes, but the increasing demand for quality is now affording refiners an opportunity to develop distinctive products. In the opinion of the author, cracking processes of the future will be of the vapor-phase type, which gives a product possessing antiknock properties that are markedly superior to those of present fuels.
The composition and distinguishing characteristics of the various families of petroleum oils are explained, including such groups as the paraffins, olefins, naphthenes, and aromatics, the last named including the naphthalenes. The products of liquid-phase cracking are said to contain varying amounts of olefins, naphthenes and aromatics, especially olefins, but all are inferior in antiknock value to California distillate of the same volatility and same distillation range; the product of vapor-phase cracking contains very much higher percentages of these three members, giving it, consequently, a very much higher antiknock value. A particular vapor-phase product, Stellarene, consisting almost entirely of the two series, olefin and naphthene, and produced by the breaking up of large molecules in the vapor phase in the presence of a catalyst, is then described in detail.