This invention relates to process for producing biphenyl esters, the process comprising: (a) contacting a feed comprising toluene, xylene or mixtures thereof with hydrogen in the presence of a hydroalkylation catalyst to produce a hydroalkylation reaction product comprising (methylcyclohexyl)toluene, wherein the hydroalkylation catalyst comprises: 1) binder present at 40 wt % or less (based upon weight of final catalyst composition), 2) a hydrogenation component present at 0.2 wt % or less (based upon weight of final catalyst composition), and 3) an acidic component comprising a molecular sieve having a twelve membered (or larger) ring pore opening, channel or pocket and a largest pore dimension of 6.0 angstroms or more present at 60 wt % or more, (based upon weight of final catalyst composition); (b) dehydrogenating the hydroalkylation reaction product using a dehydrogenation catalyst to produce a dehydrogenation reaction product comprising a mixture of methyl-substituted biphenyl compounds; (c) contacting at the dehydrogenation reaction product with an oxidizing gas to convert the methyl-substituted biphenyl compounds to biphenyl carboxylic acids; and (d) reacting the biphenyl carboxylic acids with one or more C.sub.1 to C.sub.14 alcohols to produce biphenyl esters.

This invention relates to process for producing biphenyl esters, the process comprising: (a) contacting a feed comprising toluene, xylene or mixtures thereof with hydrogen in the presence of a hydroalkylation catalyst to produce a hydroalkylation reaction product comprising (methylcyclohexyl)toluene, wherein the hydroalkylation catalyst comprises: 1) binder present at 40 wt % or less (based upon weight of final catalyst composition), 2) a hydrogenation component present at 0.2 wt % or less (based upon weight of final catalyst composition), and 3) an acidic component comprising a molecular sieve having a twelve membered (or larger) ring pore opening, channel or pocket and a largest pore dimension of 6.0 angstroms or more present at 60 wt % or more, (based upon weight of final catalyst composition); (b) dehydrogenating the hydroalkylation reaction product using a dehydrogenation catalyst to produce a dehydrogenation reaction product comprising a mixture of methyl-substituted biphenyl compounds; (c) contacting at the dehydrogenation reaction product with an oxidizing gas to convert the methyl-substituted biphenyl compounds to biphenyl carboxylic acids; and (d) reacting the biphenyl carboxylic acids with one or more C.sub.1 to C.sub.14 alcohols to produce biphenyl esters.

This invention relates to process for producing biphenyl esters, the process comprising: (a) contacting a feed comprising toluene, xylene or mixtures thereof with hydrogen in the presence of a hydroalkylation catalyst to produce a hydroalkylation reaction product comprising (methylcyclohexyl)toluene, wherein the hydroalkylation catalyst comprises: 1) binder present at 40 wt % or less (based upon weight of final catalyst composition), 2) a hydrogenation component present at 0.2 wt % or less (based upon weight of final catalyst composition), and 3) an acidic component comprising a molecular sieve having a twelve membered (or larger) ring pore opening, channel or pocket and a largest pore dimension of 6.0 angstroms or more present at 60 wt % or more, (based upon weight of final catalyst composition); (b) dehydrogenating the hydroalkylation reaction product using a dehydrogenation catalyst to produce a dehydrogenation reaction product comprising a mixture of methyl-substituted biphenyl compounds; (c) contacting at the dehydrogenation reaction product with an oxidizing gas to convert the methyl-substituted biphenyl compounds to biphenyl carboxylic acids; and (d) reacting the biphenyl carboxylic acids with one or more C.sub.1 to C.sub.14 alcohols to produce biphenyl esters.

Processes are described for separating 3,4′- and 4,4′-dimethylbiphenyl from a mixture comprising at least 3,3′-, 3,4′- and 4,4′-dimethylbiphenyl. In the processes, the mixture is cooled to produce a crystallization product comprising at least of the 4,4′-dimethylbiphenyl from the feed mixture and a first mother liquor product. The first mother liquor product is distilled to produce a bottoms stream enriched in 4,4′-dimethylbiphenyl as compared with the first mother liquor product and an overhead stream deficient in 4,4′-dimethylbiphenyl as compared with the first mother liquor product. The overhead stream is then cooled to produce a second crystallization product comprising at least part of the 3,4′-dimethylbiphenyl from the overhead stream and a second mother liquor product.

Processes are described for separating 3,4′- and 4,4′-dimethylbiphenyl from a mixture comprising at least 3,3′-, 3,4′- and 4,4′-dimethylbiphenyl. In the processes, the mixture is cooled to produce a crystallization product comprising at least of the 4,4′-dimethylbiphenyl from the feed mixture and a first mother liquor product. The first mother liquor product is distilled to produce a bottoms stream enriched in 4,4′-dimethylbiphenyl as compared with the first mother liquor product and an overhead stream deficient in 4,4′-dimethylbiphenyl as compared with the first mother liquor product. The overhead stream is then cooled to produce a second crystallization product comprising at least part of the 3,4′-dimethylbiphenyl from the overhead stream and a second mother liquor product.

Processes are described for separating 3,4′- and 4,4′-dimethylbiphenyl from a mixture comprising at least 3,3′-, 3,4′- and 4,4′-dimethylbiphenyl. In the processes, the mixture is cooled to produce a crystallization product comprising at least of the 4,4′-dimethylbiphenyl from the feed mixture and a first mother liquor product. The first mother liquor product is distilled to produce a bottoms stream enriched in 4,4′-dimethylbiphenyl as compared with the first mother liquor product and an overhead stream deficient in 4,4′-dimethylbiphenyl as compared with the first mother liquor product. The overhead stream is then cooled to produce a second crystallization product comprising at least part of the 3,4′-dimethylbiphenyl from the overhead stream and a second mother liquor product.

Disclosed is a hydroalkylation process in which the hydroalkylation catalyst is activated in the presence of a flowing fluid comprising hydrogen and a condensable agent. The presence of the condensable agent enables fast, effective activation of the hydroalkylation catalyst precursor in a cost-effective manner. It also yields superior catalyst performance.

Disclosed is a hydroalkylation process in which the hydroalkylation catalyst is activated in the presence of a flowing fluid comprising hydrogen and a condensable agent. The presence of the condensable agent enables fast, effective activation of the hydroalkylation catalyst precursor in a cost-effective manner. It also yields superior catalyst performance.

Disclosed is a hydroalkylation process in which the hydroalkylation catalyst is activated in the presence of a flowing fluid comprising hydrogen and a condensable agent. The presence of the condensable agent enables fast, effective activation of the hydroalkylation catalyst precursor in a cost-effective manner. It also yields superior catalyst performance.

In a process for dehydrogenating cyclohexylbenzene and/or alkyl-substituted cyclohexylbenzene compounds, a dehydrogenation catalyst comprising at least one Group 10 metal compound on a support is heated in the presence of hydrogen from a first temperature from 0° C. to 200° C. to a second, higher temperature from 60° C. to 500° C. at a ramp rate no more than 100° C./hour. The dehydrogenation catalyst is contacted with hydrogen at the second temperature for a time from 3 to 300 hours to produce an activated dehydrogenation catalyst. A feed comprising cyclohexylbenzene and/or an alkyl-substituted cyclohexylbenzene compound is then contacted with hydrogen in the presence of the activated dehydrogenation catalyst under conditions effective to produce a dehydrogenation reaction product comprising biphenyl and/or an alkyl-substituted biphenyl compound.