Production of Biphenyl Compounds

摘要

In a process for producing biphenyl compounds, a Cn aromatic hydrocarbon may be hydroalkylated to give C2n cycloalkylaromatic compounds and byproduct Cn saturated cyclic hydrocarbons. The C2n cycloalkylaromatic compounds are dehydrogenated to provide the biphenyl compounds. The Cn saturated cyclic hydrocarbons may also be dehydrogenated back to the corresponding Cn aromatic hydrocarbon, which may be recycled to provide additional feed. Although both the intermediate C2n cycloalkylaromatic compounds and the byproduct Cn saturated cyclic hydrocarbons should be dehydrogenated, at least part of the dehydrogenation of the Cn saturated cyclic hydrocarbons should take place in the absence of C2n or greater hydrocarbons. Thus, dehydrogenation of the byproduct Cn saturated cyclic hydrocarbons should take place at least in part separately from dehydrogenation of the C2n cycloalkylaromatic compounds.

主权项

1. A process for producing biphenyl compounds, the process comprising:
(a) contacting a hydroalkylation feed comprising Cn aromatic hydrocarbons with hydrogen in the presence of a hydroalkylation catalyst under conditions effective to produce a hydroalkylation reaction effluent comprising (i) C2n cycloalkylaromatic compounds and (ii) Cn saturated cyclic hydrocarbons, where n is an integer from 6 to 12; (b) providing at least a portion of the hydroalkylation reaction effluent to a first dehydrogenation zone, therein dehydrogenating at least a portion of the C2n cycloalkylaromatic compounds and at least a portion of the Cn saturated cyclic hydrocarbons in the presence of a first dehydrogenation catalyst under conditions effective to produce a first dehydrogenation reaction product comprising (i) a mixture of C2n biphenyl compounds; (ii) recovered Cn aromatic hydrocarbons; and (iii) unreacted Cn saturated cyclic hydrocarbons; (c) separating the first dehydrogenation reaction product into (i) a heavy dehydrogenation stream rich in the C2n biphenyl compounds, and (ii) a light dehydrogenation stream rich in the recovered Cn aromatic hydrocarbons and the unreacted Cn saturated cyclic hydrocarbons; (d) providing at least a portion of the light dehydrogenation stream to a second dehydrogenation zone separate from the first dehydrogenation zone; and (e) in the second dehydrogenation zone, dehydrogenating at least a portion of the unreacted Cn saturated cyclic hydrocarbons in the presence of a second dehydrogenation catalyst under conditions effective to produce a second dehydrogenation reaction product comprising additional recovered Cn aromatic hydrocarbons.