Selective hydrogenation process

Claim 1

A method for selectively hydrogenating a copolymer comprising monomer units of at least two different conjugated diolefins each containing a moiety C(1)= (2)- (3) = C (4) , at least one of said conjugated diolefins having less total hydrogen atoms on either the 2 and 3 carbon atoms or the 3 and 4 carbon atoms in the conjugated diolefin moiety than at least one other conjugated diolefin, comprising the steps of: (a) contacting said polymer comprising monomer units of at least two different conjugated diolefins, in solution, with hydrogen in the presence of an amount of a selective hydrogenation catalyst, sufficient to permit selective hydrogenation between i) ethylenic unsaturation of Type I groups, consisting of RCH = CH 2 ; R 2 C=CH 2 and RCH=CHR groups and Type II groups, consisting of RXC = CHR and XCH = CRX groups; ii) ethylenic unsaturation of Type I groups and Type III groups, consisting of RXC = CRX groups; iii) ethylenic unsaturation of Type II groups and Type III groups; whereby each R represents the same or a different hydrocarbyl radical and each X represents the same or a different hydrocarbyl radical or another radical capable of hindering a hydrogenation reaction, for a period of time sufficient to permit at least a portion of the ethylenic unsaturation contained in the polymer to be hydrogenated; and (b) recovering a selectively hydrogenated polymer product.

Claim 2

A method for selectively hydrogenating a copolymer comprising monomer units of at least two different conjugated diolefins each containing a moiety C(1)= (2)- (3) = C (4) , at least one of said conjugated diolefins having less total hydrogen atoms on either the 2 and 3 carbon atoms or the 3 and 4 carbon atoms in the conjugated diolefin moiety than at least one other conjugated diolefin, comprising the steps of: (a) contacting said polymer comprising monomer units of at least two different conjugated diolefins, in solution, with hydrogen in the presence of an amount of a selective hydrogenation catalyst, sufficient to permit selective hydrogenation between i) ethylenic unsaturation of Type I groups, consisting of RCH = CH 2 ; R 2 C=CH 2 and RCH=CHR groups and Type II groups, consisting of RXC = CHR and XCH = CRX groups; ii) ethylenic unsaturation of Type I groups and Type III groups, consisting of RXC = CRX groups; iii) ethylenic unsaturation of Type II groups and Type III groups; whereby each R represents the same or a different hydrocarbyl radical and each X represents the same or a different hydrocarbyl radical or another radical capable of hindering a hydrogenation reaction, for a period of time sufficient to permit at least a portion of the ethylenic unsaturation contained in the polymer to be hydrogenated; and (b) recovering a selectively hydrogenated polymer product.

Claim 5

The method of any of claims 1-3 wherein said aluminium alkyl is an aluminium trialkyl, each alkyl group containing from 1 to 4 carbon atoms.

Claim 6

The method of any of claims 1-4 wherein said Group VIII metal compound is nickel-2-ethylhexanoate.

Claim 7

The method of any of claims 1-5 wherein said selective hydrogenation is carried out at a partial hydrogen pressure in the range of 7-70 bar and at a temperature in the range of 40-110 C.

Claim 8

The method of any of claims 1-6 wherein at least one of said conjugated diolefins is unsubstituted at the 2 and 3 carbon atoms and at least one other is substituted at the 2 carbon atom of the conjugated diolefin moiety.

Claim 10

The method of any of claims 1-5 wherein said catalyst is present in an amount sufficient to provide from about 1×10 -3 to about 2×10 -2 mmoles of Group VIII metal per g of polymer and the selective hydrogenation is between Type I and Type II ethylenic unsaturation.

Claim 11

The method of any of claims 1-5 wherein said catalyst is present in an amount sufficient to provide from about 5×10 -3 to about 1×10 -1 mmoles of Group VIII metal per g of polymer and the selective hydrogenation is between Type II and Type III ethylenic unsaturation.

Claim 12

The method of any of claims 1-5 wherein said catalyst is present in an amount sufficient to provide from about 1×10 -3 to about 1×10 -1 mmoles of Group VIII metal per g of polymer and the selective hydrogenation is between Type I and Type III ethylenic unsaturation.