Process for preparing cyclohexane from benzene and methylcyclopentane with upstream benzene hydrogenation

Abstract

The present invention relates to a process for preparing cyclohexane from methylcyclopentane (MCP) and benzene. In the context of the present invention, MCP and benzene are constituents of a hydrocarbon mixture (HM1) additionally comprising dimethylpentanes (DMP), possibly cyclohexane and possibly at least one compound (low boiler) selected from acyclic C5-C6-alkanes and cyclopentane. First of all, benzene is converted in a hydrogenation step to cyclohexane (that present in the hydrocarbon mixture (HM2)), while MCP is isomerized in the presence of a catalyst, preferably of an acidic ionic liquid, to cyclohexane. After the hydrogenation but prior to the isomerization the dimethylpentanes (DMP) are removed, with initial removal of the cyclohexane present in the hydrocarbon mixture (HM2) together with DMP. This cyclohexane already present prior to the isomerization can be separated again from DMP in a downstream rectification step and isolated and/or recycled into the process for cyclohexane preparation. Between the DMP removal and MCP isomerization—if low boilers are present in the hydrocarbon mixture (HM1)—low boilers are, optionally removed. After the isomerization, the cyclohexane is isolated, optionally with return of unisomerized MCP and optionally of low boilers. Preferably, cyclohexane and/or low boilers are present in the hydrocarbon mixture (HM1), and so a low boiler removal is preferably conducted between the DMP removal from isomerization. It is additionally preferable that the removal of the cyclohexane from DMP is additionally conducted, meaning that the cyclohexane component which arises in the benzene hydrogenation and may be present in the starting mixture (HM1) is isolated and hence recovered.

Dependencies are inferred from the claim text.