Process to reduce the benzene content of gasoline

Claim 2

A process for reducing the benzene content of a gasoline precursor stream which comprises the steps of: (a) passing a gasoline precursor stream comprising from 0.5 to 5.0 mole percent benzene, 1.0 mole percent toluene, 5.0 mole percent of C 4 to C 6 paraffinic hydrocarbons, 10 mole percent C 8 to C 10 aromatic hydrocarbons and also comprising C 7 to C 9 paraffinic hydrocarbons and having a boiling point range between 90° F. and 410° F. into a fractionation zone operated at fractionation conditions and separating the gasoline precursor stream into a first hydrocarbon stream comprising C 4 to C 6 paraffinic hydrocarbons and substantially all of the benzene contained in the gasoline precursor stream and a second hydrocarbon stream comprising C 8 to C 10 aromatic hydrocarbons; (b) forming a reaction zone charge stream having an olefin to aromatic hydrocarbon ratio above 1.0:1.0 by admixing an olefinic hydrocarbon having from 2 to 4 carbon atoms per molecule into the first hydrocarbon stream; (c) passing the reaction zone charge stream into an alkylation reaction zone maintained at benzene alkylation-promoting conditions, and effecting the production of a reaction zone effluent stream which comprises an aromatic hydrocarbon having from 8 to 10 carbon atoms per molecule and C 4 to C 6 paraffinic hydrocarbons; (d) passing the reaction zone effluent stream into a separation zone and effecting the division of the reaction zone effluent stream into a light separation zone effluent stream comprising a C 3 or C 4 hydrocarbon and a heavy separation zone effluent stream comprising substantially all of the aromatic hydrocarbons contained in the reaction zone effluent stream; and, (e) admixing the heavy separation zone effluent stream with the second hydrocarbon stream.

Claim 3

The process of claim 1 further characterized in that the reaction zone effluent stream contains less than 1.0 mole percent benzene.

Claim 4

The process of claim 1 further characterized in that the alkylation reaction zone contains a bed of an SPA catalyst.

Claim 5

The process of claim 3 further characterized in that the gasoline precursor stream comprises C 6 to C 9 aromatic hydrocarbons produced in a catalytic reforming zone.

Claim 6

A process for reducing the benzene content of a gasoline precursor stream which comprises the steps of: (a) passing a gasoline precursor stream comprising from 0.5 to 5.0 mole percent benzene, 1.0 mole percent toluene, 5.0 mole percent of C 4 to C 6 paraffinic hydrocarbons, 10 mole percent of C 8 to C 10 aromatic hydrocarbons and also comprising C 7 to C 9 paraffinic hydrocarbons and having a boiling point range between 90° F. and 410° F. into a fractionation zone operated at fractionation conditions and separating the gasoline precursor stream into a first hydrocarbon stream comprising C 4 to C 6 paraffinic hydrocarbons and substantially all of the benzene contained in the gasoline precursor stream and a second hydrocarbon stream comprising toluene and substantially all of the C 8 to C 10 aromatic hydrocarbons contained in the gasoline precursor stream; (b) forming a reaction zone charge stream having an olefin to aromatic hydrocarbon ratio from about 1.4:1:0 to 2.0:1.0 by admixing a sufficient quantity of an olefin feed stream comprising a C 3 or C 4 olefinic hydrocarbon into the first hydrocarbon stream; (c) contacting the reaction zone charge stream with an SPA catalyst in an alkylation reaction zone maintained at benzene alkylation-promoting conditions, and effecting the production of a reaction zone effluent stream which comprises an aromatic hydrocarbon having 9 or 10 carbon atoms per molecule and C 4 to C 6 paraffinic hydrocarbons and which contains less than 1.0 mole percent benzene; (d) passing the reaction zone effluent stream into a separation zone and effecting the division of the reaction zone effluent stream into a light separation zone effluent stream comprising a C 3 or C 4 hydrocarbon and a heavy separation zone effluent stream comprising substantially all of the aromatic hydrocarbons contained in the reaction zone effluent stream; and, (e) admixing the heavy separation zone effluent stream and the second hydrocarbon stream.

Claim 7

A process for reducing the benzene content of a gasoline precursor stream which comprises the steps of: (a) passing a gasoline precursor stream comprising from 0.5 to 5.0 mole percent benzene, 1.0 mole percent toluene, 5.0 mole percent of C 4 to C 6 paraffinic hydrocarbons, 10 mole percent of C 8 to C 10 aromatic hydrocarbons and also comprising C 7 to C 9 paraffinic hydrocarbons and having a boiling point range between 90° F. and 410° F. into a fractionation zone operated at fractionation conditions and separating the gasoline precursor stream into a first hydrocarbon stream comprising C 4 to C 6 paraffinic hydrocarbons and substantially all of the benzene contained in the gasoline precursor stream and a second hydrocarbon stream comprising toluene and substantially all of the C 8 to C 10 aromatic hydrocarbons contained in the gasoline precursor stream; (b) forming a reaction zone charge stream having an olefin to aromatic hydrocarbon ratio from about 1.4:1:0 to 2.0:1.0 by admixing a sufficient quantity of an olefin feed stream comprising a C 3 or C 4 olefinic hydrocarbon into the first hydrocarbon stream; (c) contacting the reaction zone charge stream with an SPA catalyst in an alkylation reaction zone maintained at benzene alkylation-promoting conditions, and effecting the production of a reaction zone effluent stream which comprises an aromatic hydrocarbon having 9 or 10 carbon atoms per molecule and C 4 to C 6 paraffinic hydrocarbons and which contains less than 1.0 mole percent benzene; (d) passing the reaction zone effluent stream into a separation zone and effecting the division of the reaction zone effluent stream into a light separation zone effluent stream comprising a C 3 or C 4 hydrocarbon and a heavy separation zone effluent stream comprising substantially all of the aromatic hydrocarbons contained in the reaction zone effluent stream; and, (e) admixing the heavy separation zone effluent stream and the second hydrocarbon stream.

Claim 8

The process of claim 5 further characterized in that the olefin to aromatic hydrocarbon ratio of the reaction zone charge stream is from about 1.5:1 to 1.8:1.

Claim 9

The process of claim 6 further characterized in that the reaction zone charge stream is a mixed phase stream when contacted with the SPA catalyst.

Claim 10

The process of claim 7 further characterized in that the olefin feed stream comprises propylene and propane.

Claim 11

The process of claim 7 further characterized in that a portion of the light separation zone effluent stream is recycled by admixture into the first hydrocarbon stream and in that the light separation zone effluent stream comprises propylene.