Production and separation of 3,3'-, 3,4′- and 4,4′-dimethyl biphenyl isomers

Abstract

In a process for producing one or more 3,3'-, 3,4′- and 4,4′-dimethyl biphenyl isomers, a feed comprising toluene is contacted with hydrogen in the presence of a hydroalkylation catalyst under conditions effective to produce a hydroalkylation reaction product comprising (methylcyclohexyl)toluenes. At least part of the hydroalkylation reaction product is dehydrogenated in the presence of a dehydrogenation catalyst under conditions effective to produce a dehydrogenation reaction product comprising a mixture of dimethyl biphenyl isomers. The dehydrogenation reaction product is then separated into at least a first stream containing one or more 3,3′-, 3,4′- and 4,4′-dimethyl biphenyl isomers and at least one second stream comprising one or more 2,X′-dimethyl biphenyl isomers (where X is 2, 3, or 4). The 3,3′-, 3,4′- and 4,4′-dimethyl biphenyl isomers are then separated utilizing selective adsorption.