Abstract: The invention concerns a process for the production of paraxylene and an apparatus suitable for said process. The process separates the overhead from a xylenes re-run into a xylene-rich stream and a xylene-lean stream. The xylene-lean stream is isomerized under conditions such that the xylenes are in the liquid phase.

Abstract: A method for producing efficiently a highly pure 1-(m-ethylphenyl)-1-phenylethane or m-ethylphenylphenylmethane which are used as the starting materials for preparing medicines and other organic compounds. The method comprises the step of reacting a diaryl compound with benzene or alkylbenzene in the presence of an acid catalyst selected from the group consisting of AlCl.sub.3, AlBr.sub.3, HF.BF.sub.3 complex and Y-type zeolites.

Abstract: Methods are provided for effecting the acid catalyzed transfer of alkyl substituents from a first benzenoid specie to a second benzenoid specie at an improved rate. According to a preferred embodiment, the first and second benzenoid species are blended together with an effective amount of acid catalyst. An amount effective to improve the rate of transalkylation of at least one polynuclear aromatic hydrocarbon is then added to the blend which is maintained at a temperature above room temperature for a period of time sufficient to allow a substantial degree of transalkylation to occur.According to another preferred embodiment, a mixture of benzenoid species such as is found in a fuel or a chemical feedstock is improved through the acid catalyzed transalkylization reaction enhanced by the addition of a polynuclear aromatic hydrocarbon.