EFFECT OF WASTE TIRES AND WASTE TIRE COMPONENTS ON HYDROCRACKING AND HETEROATOM REMOVAL REACTIONS USING MODEL SYSTEMS

The effect of waste tires and waste tire components, such as styrene b utadiene rubber (SBR), carbon black, and solid residues from waste tir e liquefaction, on hydrocracking reactions that occur in coal and wast e tire coliquefaction was evaluated using the model compound 4-(1-naph ythylmethyl)bibenzyl (NMBB). The reactions were performed thermally an d catalytically using slurry phase catalyst precursors including molyb denum naphthenate, iron naphthenate, and other iron precursors. The re action conditions were 400 degrees C for 30 min with a H-2 pressure of 8.7 MPa introduced at ambient temperature. Carbon black was active fo r hydrocracking NMBB and selective for cleaving the naphthyl-methylene bond and resulted, in 79.1 +/- 2.7% hydrocracking while the waste tir es themselves, SBR, and untreated solid waste tire residues were not a ctive, yielding between 11.3 +/- 2.2 and 32.5 +/- 3.1% hydrocracking. However, when the residue from the liquefaction of waste tires was hea t-treated and then reacted with NMBB, the treated residue showed subst antial activity for promoting hydrocracking. The amount of activity wa s dependent upon the composition of the residue. The heat-treated carb on black-rich residue yielded 52.9 +/- 1.7% hydrocracking while the mi neral-rich residue yielded 99.7 +/- 2.1%. Higher activity was obtained when the residues were reacted in the presence of molybdenum naphthen ate and excess-sulfur. In addition, the effect of carbon black and hea t-treated residues from waste tires reacted individually and in conjun ction with molybdenum naphthenate was examined for heteroatom removal and hydrogenation of dibenzothiophene and 5-methyl-8-(1-methylethyl)di benzothiopen-4-ol (MMDH). Carbon black and the heat-treated residues, particularly in conjunction with molybdenum naphthenate and excess sul fur, promoted these reactions. The substituted MMDH was more reactive and responsive to catalytic promotion by these agents than was its uns ubstituted analogue, dibenzothiophene.