Combination process for upgrading naphtha

Claim 2

A process for upgrading a naphtha-boiling-range hydrocarbon to useful products which comprises: (1) separating said naphtha just below the boiling point of methylcyclopentane into a light naphtha fraction containing C 6 paraffins and lower-boiling hydrocarbons and a heavy naphtha fraction containing methylcyclopentane and higher-boiling hydrocarbons; (2) reforming said heavy naphtha fraction under reforming conditions to produce a reformate enriched in aromatic compounds compared with said heavy naphtha fraction; (3) passing at least a portion of said reformate together with said light naphtha fraction in contact with a ZSM-5-type zeolite catalyst under aromatization conditions including a pressure from 0.5 to 68 atmospheres and a temperature from 343° to 649° C. to produce an aromatics-enriched effluent; (4) separating said aromatics-enriched effluent into a C 4 - fraction and a C 5 + fraction; and (5) recovering said C 5 + fraction as said product.

Claim 3

The process of claim 1 wherein the naphtha is a C 5 to C 8 straight-run naphtha and all of said reformate is passed in contact with said ZSM-5-type catalyst, and said product is sent for recovery of the benzene, toluene and xylene components therein.

Claim 4

The process of claim 1 wherein said reformate is separated into a first fraction boiling just below xylene and a second fraction containing xylene and higher-boiling components, said first fraction is said portion which is passed in contact with said ZSM-5-type catalyst, said product is sent for recovery of the benzene, toluene and xylene components thereof, and said second fraction is isomerized to optimize the xylene content thereof.

Claim 5

The process of claim 1 further comprising separating a C 3 /C 4 fraction from said aromatics-enriched effluent, and recycling said C 3 /C 4 fraction in contact with said ZSM-5-type catalyst.

Claim 6

The process of claim 1 wherein said ZSM-5-type catalyst is the Zn-H-ZSM-5 form.

Claim 7

The process of claim 1 wherein said ZSM-5-type catalyst is the H-ZSM-5 form.

Claim 8

The process of claim 1 wherein said aromatization conditions include a temperature from 500° to 540° C. and a pressure from 1 to 5 atmospheres, and no added hydrogen.

Claim 9

A process for upgrading a naphtha-boiling-range hydrocarbon to useful products, including a high-octane gasoline having a research octane number of at least 90 (Clear), which comprises: (1) separating said naphtha just below the boiling point of methylcyclopentane into a light naphtha fraction containing C 6 paraffins and lower-boiling hydrocarbons and a heavy naphtha fraction containing methylcyclopentane and higher-boiling hydrocarbons; (2) reforming said heavy naphtha fraction under reforming conditions selected to increase the octane rating of the gasoline-boiling-range product; (3) fractionating the product of the reforming operation into a light reformate which contains a substantial amount of C 7 - paraffins and a heavy reformate fraction which contains most of the toluene and the remaining high-boiling hydrocarbons; (4) forming aromatics from said paraffins by passing said light reformate together with said light naphtha fraction in contact with a ZSM-5-type zeolite catalyst under aromatization conditions including a pressure from 0.5 to 35 atmospheres, a temperature from 454° to 556° C. and no added hydrogen and recovering an aromatics-enriched effluent from said aromatization operation; (5) separating said aromatics-enriched effluent into a C 4 - fraction and a C 5 + fraction; and (6) combining said C 5 + fraction with said heavy reformate to produce said high-octane gasoline.

Claim 10

A process for upgrading a naphtha-boiling-range hydrocarbon to useful products, including a high-octane gasoline having a research octane number of at least 90 (Clear), which comprises: (1) separating said naphtha just below the boiling point of methylcyclopentane into a light naphtha fraction containing C 6 paraffins and lower-boiling hydrocarbons and a heavy naphtha fraction containing methylcyclopentane and higher-boiling hydrocarbons; (2) reforming said heavy naphtha fraction under reforming conditions selected to increase the octane rating of the gasoline-boiling-range product; (3) fractionating the product of the reforming operation into a light reformate which contains a substantial amount of C 7 - paraffins and a heavy reformate fraction which contains most of the toluene and the remaining high-boiling hydrocarbons; (4) forming aromatics from said paraffins by passing said light reformate together with said light naphtha fraction in contact with a ZSM-5-type zeolite catalyst under aromatization conditions including a pressure from 0.5 to 35 atmospheres, a temperature from 454° to 556° C. and no added hydrogen and recovering an aromatics-enriched effluent from said aromatization operation; (5) separating said aromatics-enriched effluent into a C 4 - fraction and a C 5 + fraction; and (6) combining said C 5 + fraction with said heavy reformate to produce said high-octane gasoline.

Claim 11

The process of claim 8 further comprising separating a C 3 /C 4 fraction from said aromatics-enriched effluent and recycling said C 3 /C 4 fraction in contact with said ZSM-5-type catalyst.