Catalyst activation and resins therefrom
The present invention relates to the removal of hydrocarbon residues from a catalyst and more specifically the air activation of a catalyst containing hydrocarbon residues. It also relates to extruded pipe and utility conduit resins comprising polyethylene, household/industrial chemicals container resins, and to a polyethylene resin particularly suitable for large parts by blow molding and sheet extrusion procedures, wherein the resin is made by a process using an activated chromium and titanium-based catalyst.
1. A catalyst activation process comprising:
(a) heating a chromium and titanium-based supported catalyst having a hydrocarbon residue, in an inert atmosphere to about 370-540° C.;
(b) introducing an oxidant to said catalyst in a controlled manner for a hold period sufficient to drive off the hydrocarbon residue wherein the addition of air is controlled so that the observed temperature spike or exotherm does not exceed 590° C.; and
(c) oxidizing the catalyst at a temperature and for a time sufficient to activate the catalyst.
2. The process according to claim 1 , wherein step (c) further comprises contacting said catalyst with an atmosphere consisting essentially of air.
3. The process according to claim 2 , wherein step (c) further comprises contacting said catalyst with an atmosphere consisting essentially of air between about 425° C. (800° F.) and about 870° C. (1600° F.).
4. The process according to claim 1 , wherein the temperature in (a) does not exceed about 400° C. (750° F.), and the temperature in (b) does not exceed about 425° C. (800° F.).
5. The process according to claim 1 , wherein said oxidant is air.
6. The process according to claim 5 , wherein both (a) and (b) include a step wherein the gases introduced are preheated to a temperature of about 400° C. or less.
7. The process according to claim 6 , wherein both (a) and (b) include a step wherein the gases introduced are preheated to a temperature of about 200° C. or less.
8. The process according to claim 1 , wherein said supported catalyst further comprises a metal selected from the group consisting of zirconium, aluminum, boron, and mixtures thereof.
9. The process according to claim 1 , wherein said support is silica.
10. The process according to claim 1 , wherein said support is silica-alumina.
11. The process according to claim 1 , wherein (b) includes controlling the temperature by controlling the amount of oxidant introduced.
12. The process according to claim 5 , wherein (b) includes controlling the temperature by controlling the temperature of the air introduced.
13. The process according to claim 5 , wherein (b) includes controlling the temperature by controlling the amount of the air introduced and controlling the temperature of the air introduced.
14. The process according to claim 5 , wherein in (a) the inert gas is preheated to a temperature of about 450° C. (850° F.).
15. The process of claim 5 wherein in (a) the inert gas is preheated to a temperature of no more than 200° C. (400° F.).
16. The process according to claim 1 , wherein said catalyst further comprises hydrocarbon residues present on the support as a result of the deposition of chromium and titanium thereon from solution.
17. The process according to claim 1 , wherein the temperature in (a) does not exceed about 450° C. (850° F.).
18. The process according to claim 1 , wherein the temperature in (b) does not exceed about 450° C. (850° F.).
19. The process according to claim 1 , wherein (c) further comprises completing the activation at said temperature and under said oxidizing atmosphere for a period of from 1 minute to 10 hours.
20. The process according to claim 19 , wherein said period in (c) is from 4 to 8 hours.
21. The process according to claim 19 , wherein said oxidizing atmosphere in (c) is an atmosphere consisting essentially of air.
22. The process according to claim 20 , wherein said oxidizing atmosphere in (c) is an atmosphere consisting essentially of air.
23. The process according to claim 1 , wherein said catalyst consists essentially of chromium and titanium on a silica support.
24. The process according to claim 1 , wherein said catalyst comprises about 1.0±0.5 wt. % chromium and 1.0 to 5.0 wt. % titanium, supported on silica, the weight percents based on the weight of the silica support.
25. The process according to claim 1 , wherein the oxidant is introduced to said catalyst in an atmosphere having an oxidant concentration of less than or equal to 2.8 volume percent.
26. The process according to claim 1 , wherein the oxidant is introduced to said catalyst in a fluidized bed at a flow rate of less than or equal to 20 cubic feet per minute.
27. The process according to claim 4 , wherein the oxidant is introduced to said catalyst in an atmosphere having an oxidant concentration of less than or equal to 2.8 volume percent.
28. The process according to claim 4 , wherein the oxidant is introduced to said catalyst in a fluidized bed at a flow rate of less than or equal to 20 cubic feet per minute.
29. A catalyst activation process comprising:
heating a chromium and titanium-based supported catalyst having a hydrocarbon residue in an inert atmosphere at a first temperature of about 370° C. to about 450° C.;
introducing an oxidant to said catalyst for a hold period sufficient to drive off the hydrocarbon residue wherein introduction of said oxidant provides an increase in temperature from the first temperature to a second temperature that is less than or equal to 510° C.; and then
oxidizing the catalyst at a third temperature of about 425° C. to about 870° C. for a time sufficient to activate the catalyst.
30. A catalyst activation process comprising:
heating a chromium and titanium-based supported catalyst having a hydrocarbon residue, in an inert atmosphere at a first temperature of about 370° C. to about 540° C. and hold for up to 6 hours;
cooling the inert atmosphere to a second temperature less than the first temperature;
introducing an oxidant to said catalyst for a hold period sufficient to drive off the hydrocarbon residue wherein the introduction of said oxidant provides an increase in temperature from the second temperature to a third temperature of about 510° C. or less; and
increasing the oxidant concentration to oxidize the catalyst at a fourth temperature of about 425° C. to about 870° C. for a time sufficient to activate the catalyst,
wherein the oxidant is added to the inert atmosphere at a rate to provide an oxidant concentration therein of less than or equal to 2.8 volume percent while maintaining the third temperature at about 590° C. or less.