THE CHEMICAL-COMPOSITION OF CATALYTIC AIR BLOWN ASPHALT

Air blowing of paving grade asphalt has been carried out to produce in dustrial grade asphalt. Chemical changes during air blowing of asphalt , in the presence of transition metal salts, have been evaluated by ad sorption-desorption chromatography. The elemental composition and stru ctural parameters based on ultraviolet (u.v.) and nuclear magnetic res onance (n.m.r.) spectra indicate that straight chain hydrocarbons are converted to naphthenes, which in turn are dehydrogenated to form arom atic hydrocarbons during air blowing. The blown product becomes more c omplex and condensed leading to an increase in molecular weight. These changes are accelerated by an active catalyst. A general transformati on mechanism has been proposed.