SECONDARY COKING AND CRACKING OF SHALE OIL VAPORS FROM PYROLYSIS OF HYDROPYROLYSIS OF A KENTUCKY CLEVELAND OIL-SHALE IN A 2-STAGE REACTOR

It is widely recognized that secondary reactions which are mainly asso ciated with minerals during oil shale retorting have a marked influenc e on the product yields and compositions. To understand these phenomen a more clearly, the secondary reactions of shale oil vapours from the pyrolysis (or hydropyrolysis) of Kentucky Cleveland oil shale were exa mined in a two-stage, fixed-bed reactor in flowing nitrogen or hydroge n at pressures of 0.1-1 5 M Pa. The vapours from pyrolysis (first stag e) were passed through a second stage containing combusted shale, upgr ading catalyst or neither. Carbon conversion to volatile products in t he first stage increased from 49% during thermal pyrolysis to 81% at 1 5 MPa H-2 partial pressure. During thermal pyrolysis, total pressure h ad only a slight effect on carbon removal from the raw shale and subse quent deposition on to the porous solids in the second stage. Carbon d eposition on to the combusted shale in the second stage was reduced to zero at 15 MPa H-2 partial pressure. The n-alkane distributions of th e oils as determined by gas chromatography clearly demonstrated that h igher hydrogen pressure, contact with combusted shale, or both contrib uted to lower-molecular-weight products.