Abstract: Depolymerization or molecular weight reduction of polymers and gelled polymers containing internal unsaturation along the polymer backbone is performed in the presence of a molybdenum or tungsten compounds having the structural formula:M(NR.sub.1)(OR.sub.2).sub.2 (CHR.sub.3)wherein M is molybdenum or tungsten;R.sub.1 and R.sub.2 are unsubstituted or halo-substituted alkyl, aryl, aralkyl groups or silicon-containing analogs thereof;R.sub.3 is an alkyl, aryl, aralkyl group of any substituent that results from the initial reaction between the M.dbd.CHR.sub.3 complex and an olefin treating agent.

Abstract: This is a catalyst and a process for partially hydrogenating polycyclic and monocyclic aromatic hydrocarbons such as benzene, naphthalenes, biphenyls, and alkylbenzenes to produce the corresponding cycloolefins. The catalyst is a hydrogenation catalyst comprising ruthenium on a composite support. It is a process in which the product cycloolefin is produced in high yield and with high selectivity.