Olefin polymerization using activated chromium catalyst treated with tertiary alcohol

Claim 2

A polymerization process comprising contacting at least one mono-1-olefin having 2 to 8 carbon atoms per molecule with a catalyst produced by a process comprising: forming a silica-titania supported chromium catalyst precursor, the silica-titania containing 0.1 to 10 weight percent titanium, said chromium being present in an amount within the range of 0.1 to 5 weight percent; activating said silica-titania supported chromium catalyst precursor in an oxygen-containing ambient at a temperature within the range of 500° to 900° C.; contacting said thus activated silica-titania supported chromium catalyst precursor with a tertiary alcohol in an amount up to about 20 molecules per atom of chromium and directly thereafter reactivating the resulting treated catalyst in an oxygen-containing ambient at a temperature within the range of 200° to 600° C.

Claim 3

A process according to claim 1 wherein said oxygen-containing ambient is air.

Claim 4

A process according to claim 2 wherein said calcining is carried out at 600° to 800° C.

Claim 5

A process according to claim 1 wherein said titanium is present in an amount within the range of 1 to 6 weight percent titanium based on the weight of said support.

Claim 6

A process according to claim 1 wherein the support of said silica-titania supported catalyst precursor is a silica-titania cogel.

Claim 7

A process according to claim 1 wherein the support of said silica-titania supported catalyst precursor is produced by impregnation of silica gel with a titanium compound.

Claim 8

A process according to claim 6 wherein said impregnation is carried out under aqueous conditions.

Claim 9

A process according to claim 6 wherein said impregnation is carried out anhydrously.

Claim 10

A process according to claim 1 wherein said reactivating is carried out in air.

Claim 11

A process according to claim 9 wherein said reactivating is carried out at a temperature of 300° to 400° C. for a time within the range of 15 minutes to 5 hours.

Claim 12

A process according to claim 1 wherein said tertiary alcohol is one of tertiary butanol, tertiary amyl alcohol, 2-methyl-2-pentanol, 3-ethyl-3-pentanol, 2,2,4-trimethyl-4-pentanol and mixtures thereof.

Claim 13

A process according to claim 11 wherein said tertiary alcohol is tertiary-butanol.

Claim 14

A process according to claim 1 wherein said contacting is carried out for a time within the range of one minute to four hours.

Claim 15

A process according to claim 13 wherein said time is within the range of 30 minutes to 2 hours.

Claim 16

A process according to claim 14 wherein said tertiary alcohol is used in an amount within the range of one molecule of alcohol per atom of chromium to 10 molecules of alcohol per atom of chromium.

Claim 17

A process according to claim 1 wherein said tertiary alcohol is used in an amount within the range of 1 molecule of alcohol per atom of chromium to 10 molecules of alcohol per atom of chromium.

Claim 18

A process according to claim 1 wherein said contacting is done by forming a slurry of said silica-titania supported chromium catalyst precursor in an inert diluent containing said tertiary alcohol.

Claim 19

A process according to claim 17 wherein said diluent is a hydrocarbon containing from about 3 to about 12 carbon atoms.

Claim 20

A process according to claim 18 wherein said hydrocarbon is n-pentane or n-hexane.

Claim 21

A process according to claim 1 wherein said chromium is present in an amount within the range of 0.5 to 1.2 weight percent based on the weight of the support of said silica-titania supported chromium catalyst precursor.

Claim 22

A process according to claim 1 wherein said contacting is done by slurrying said silica-titania supported chromium catalyst precursor in an inert diluent containing said tertiary alcohol, said tertiary alcohol is present in an amount within the range of 1 molecule of alcohol per atom of chromium to 10 molecules of alcohol per atom of chromium, said contacting is carried out for a time of one minute to 4 hours; wherein said tertiary alcohol is selected from tertiary butanol, tertiary amyl alcohol, 2-methyl-2-pentanol, 3-ethyl-3-pentanol, 2,2,4-trimethyl-4-pentanol and mixtures thereof, wherein said reactivating is carried out at a temperature of 300° to 400° C. in air and said activated silica-titania supported chromium catalyst precursor is produced by calcination in air at a temperature of 600° to 800° C. and wherein titanium is present in the support of said silica-titania supported chromium catalyst precursor in an amount within the range of 0.5 to 5 weight percent based on the weight of said support.

Claim 23

A process according to claim 21 wherein said mono-1-olefin is selected from ethylene, propylene, 1-butene, and 1-hexene.

Claim 24

A process according to claim 21 wherein said mono-1-olefin comprises ethylene.

Claim 25

A process according to claim 21 wherein said polymerization is carried out at a temperature within the range of 66° to 110° C.

Claim 26

A process according to claim 1 wherein said mono-1-olefin is selected from ethylene, propylene, 1-butene, and 1-hexene.

Claim 27

A process according to claim 1 wherein said mono-1-olefin comprises ethylene.

Claim 28

A process according to claim 1 wherein said polymerization is carried out at a temperature within the range of 66° to 110° C.

Claim 29

A polymerization process comprising contacting ethylene under slurry conditions in isobutane with a catalyst produced by a process comprising: forming a silica-titanium cogel containing 1-6 weight percent titanium, said cogel also containing a chromium compound in an amount sufficient to give 0.5-1.2 weight percent chromium; activating said thus formed chromium-containing cogel in air at 600° to 800° C. for 2 to 5 hours to form a catalyst precursor; contacting said thus activated silica-titania supported chromium catalyst precursor with a hydrocarbon solution of a tertiary-butyl alcohol in an amount sufficient to give 1 to 10 atoms of alcohol per atom of chromium; gently drying to remove volatile alcohol and hydrocarbon; and directly thereafter reactivating the resulting treated catalyst in air at a temperature within the range of 200° to 600° C.

Claim 30

A polymerization process comprising contacting ethylene under slurry conditions in isobutane with a catalyst produced by a process comprising: forming a silica-titanium cogel containing 1-6 weight percent titanium, said cogel also containing a chromium compound in an amount sufficient to give 0.5-1.2 weight percent chromium; activating said thus formed chromium-containing cogel in air at 600° to 800° C. for 2 to 5 hours to form a catalyst precursor; contacting said thus activated silica-titania supported chromium catalyst precursor with a hydrocarbon solution of a tertiary-butyl alcohol in an amount sufficient to give 1 to 10 atoms of alcohol per atom of chromium; gently drying to remove volatile alcohol and hydrocarbon; and directly thereafter reactivating the resulting treated catalyst in air at a temperature within the range of 200° to 600° C.