A hydrocarbon conversion process is described. The process includes contacting in a reactor an inert gas with one or more catalyst compositions suitable for methylation of toluene and hydrogenation of phenol; contacting a reducing agent with the one or more catalyst compositions under conditions suitable for reducing metal oxide content of the catalyst composition; contacting at least part of toluene and/or benzene-containing with a oxygenate in the presence of the one or more catalyst compositions and under conditions effective to convert toluene to xylenes and produce a reactor effluent stream comprising para-xylene and having a lower concentration of phenol than the toluene-containing stream; separating at least one para-xylene-enriched stream from the reactor effluent stream; and separating from the at least one para-xylene enriched stream at least one toluene-enriched stream and at least one para-xylene-product stream. An apparatus for carrying out such a process is also described.

A hydrocarbon conversion process is described. The process includes contacting in a reactor an inert gas with one or more catalyst compositions suitable for methylation of toluene and hydrogenation of phenol; contacting a reducing agent with the one or more catalyst compositions under conditions suitable for reducing metal oxide content of the catalyst composition; contacting at least part of toluene and/or benzene-containing with a oxygenate in the presence of the one or more catalyst compositions and under conditions effective to convert toluene to xylenes and produce a reactor effluent stream comprising para-xylene and having a lower concentration of phenol than the toluene-containing stream; separating at least one para-xylene-enriched stream from the reactor effluent stream; and separating from the at least one para-xylene enriched stream at least one toluene-enriched stream and at least one para-xylene-product stream. An apparatus for carrying out such a process is also described.

A hydrocarbon conversion process is described. The process includes contacting in a reactor an inert gas with one or more catalyst compositions suitable for methylation of toluene and hydrogenation of phenol; contacting a reducing agent with the one or more catalyst compositions under conditions suitable for reducing metal oxide content of the catalyst composition; contacting at least part of toluene and/or benzene-containing with a oxygenate in the presence of the one or more catalyst compositions and under conditions effective to convert toluene to xylenes and produce a reactor effluent stream comprising para-xylene and having a lower concentration of phenol than the toluene-containing stream; separating at least one para-xylene-enriched stream from the reactor effluent stream; and separating from the at least one para-xylene enriched stream at least one toluene-enriched stream and at least one para-xylene-product stream. An apparatus for carrying out such a process is also described.

A process for manufacturing a carboxylic acid is provided, in one aspect, the process comprises oxidizing a feedstock comprising a substituted aromatic hydrocarbon to form a liquid-phase aromatic carboxylic acid; crystallizing at least a portion of the liquid-phase aromatic carboxylic acid in the presence of oxygen and an oxidation catalyst in a first crystallizer to form solid aromatic carboxylic acid, under reaction conditions suitable to oxidize unreacted feedstock to form additional aromatic carboxylic acid; and crystallizing at least a portion of the first crystallization effluent in the presence of oxygen and an oxidation catalyst in a second crystallizer to form additional solid aromatic carboxylic acid, under reaction conditions suitable to oxidize unreacted feedstock to form additional aromatic carboxylic acid, wherein the oxygen is present in a gaseous phase inside the second crystallizer in an amount of no more than 11% by volume on a dry basis.

A process for manufacturing a carboxylic acid is provided, in one aspect, the process comprises oxidizing a feedstock comprising a substituted aromatic hydrocarbon to form a liquid-phase aromatic carboxylic acid; crystallizing at least a portion of the liquid-phase aromatic carboxylic acid in the presence of oxygen and an oxidation catalyst in a first crystallizer to form solid aromatic carboxylic acid, under reaction conditions suitable to oxidize unreacted feedstock to form additional aromatic carboxylic acid; and crystallizing at least a portion of the first crystallization effluent in the presence of oxygen and an oxidation catalyst in a second crystallizer to form additional solid aromatic carboxylic acid, under reaction conditions suitable to oxidize unreacted feedstock to form additional aromatic carboxylic acid, wherein the oxygen is present in a gaseous phase inside the second crystallizer in an amount of no more than 11% by volume on a dry basis.

A process for manufacturing a carboxylic acid is provided, in one aspect, the process comprises oxidizing a feedstock comprising a substituted aromatic hydrocarbon to form a liquid-phase aromatic carboxylic acid; crystallizing at least a portion of the liquid-phase aromatic carboxylic acid in the presence of oxygen and an oxidation catalyst in a first crystallizer to form solid aromatic carboxylic acid, under reaction conditions suitable to oxidize unreacted feedstock to form additional aromatic carboxylic acid; and crystallizing at least a portion of the first crystallization effluent in the presence of oxygen and an oxidation catalyst in a second crystallizer to form additional solid aromatic carboxylic acid, under reaction conditions suitable to oxidize unreacted feedstock to form additional aromatic carboxylic acid, wherein the oxygen is present in a gaseous phase inside the second crystallizer in an amount of no more than 11% by volume on a dry basis.

A process for selective oxidation of at least one dimethylbiphenyl compound to the corresponding biphenyldicarboxylic acid, where the dimethylbiphenyl compound is supplied to at least one reaction zone together with an acidic solvent, an oxidizing medium, and a catalyst comprising cobalt, manganese, and bromine. The dimethyl biphenyl compound and oxidizing medium are contacted with the catalyst in the at least one reaction zone at a temperature of 150 to 210 C. to oxidize the dimethylbiphenyl compound to the corresponding biphenyldicarboxylic acid. The supply of dimethylbiphenyl compound to the at least one reaction zone is then terminated, but the supply of oxidizing medium and catalyst is continued with the at least one reaction zone at a temperature of 150 to 210 C. A reaction product comprising at least 95 wt % of the biphenyldicarboxylic acid based on the total weight of oxidized dimethylbiphenyl compound is then recovered from the at least one reaction zone.

A process for selective oxidation of at least one dimethylbiphenyl compound to the corresponding biphenyldicarboxylic acid, where the dimethylbiphenyl compound is supplied to at least one reaction zone together with an acidic solvent, an oxidizing medium, and a catalyst comprising cobalt, manganese, and bromine. The dimethyl biphenyl compound and oxidizing medium are contacted with the catalyst in the at least one reaction zone at a temperature of 150 to 210 C. to oxidize the dimethylbiphenyl compound to the corresponding biphenyldicarboxylic acid. The supply of dimethylbiphenyl compound to the at least one reaction zone is then terminated, but the supply of oxidizing medium and catalyst is continued with the at least one reaction zone at a temperature of 150 to 210 C. A reaction product comprising at least 95 wt % of the biphenyldicarboxylic acid based on the total weight of oxidized dimethylbiphenyl compound is then recovered from the at least one reaction zone.

A process for selective oxidation of at least one dimethylbiphenyl compound to the corresponding biphenyldicarboxylic acid, where the dimethylbiphenyl compound is supplied to at least one reaction zone together with an acidic solvent, an oxidizing medium, and a catalyst comprising cobalt, manganese, and bromine. The dimethyl biphenyl compound and oxidizing medium are contacted with the catalyst in the at least one reaction zone at a temperature of 150 to 210 C. to oxidize the dimethylbiphenyl compound to the corresponding biphenyldicarboxylic acid. The supply of dimethylbiphenyl compound to the at least one reaction zone is then terminated, but the supply of oxidizing medium and catalyst is continued with the at least one reaction zone at a temperature of 150 to 210 C. A reaction product comprising at least 95 wt % of the biphenyldicarboxylic acid based on the total weight of oxidized dimethylbiphenyl compound is then recovered from the at least one reaction zone.

A process for oxidizing methyl-substituted biphenyl compounds comprises contacting a mixture comprising isomers of at least one methyl-substituted biphenyl compound with a source of oxygen, wherein the mixture comprises at least 20 wt % of isomer(s) having a methyl group at a 2-position or a 3-position on at least one benzene ring and at least 50 wt % of isomer(s) having a methyl group at a 4-position on at least one benzene ring, wherein said percentages are based on the total weight of the at least one methylbiphenyl compound in the mixture.