AQUEOUS METHODS FOR TITANATING A CHROMIUM/SILICA CATALYST WITH AN ALKALI METAL
Methods for making titanated silica supports, titanated chromium/silica pre-catalysts, and activated titanated chromium/silica catalysts are disclosed in which hydrogen peroxide and an alkali metal precursor are used during catalyst preparation. Resulting titanated chromium/silica pre-catalysts often contain silica, 0.1 to 5 wt. % chromium, 0.1 to 10 wt. % titanium, and less than or equal to 4 wt. % carbon, and further contain a bound alkali metal or zinc at a molar ratio of alkali metal:titanium or zinc:titanium from 0.02:1 to 3:1 and/or at an amount in a range from 0.01 to 2 mmol of alkali metal or zinc per gram of the silica. High melt index potential activated titanated chromium/silica catalysts can be used to polymerize olefins to produce, for example, ethylene based homopolymers and copolymers having HLMI values of greater than 30 g/10 min.
1 . A titanated silica support comprising:
a silica;
from 0.1 to 10 wt. % titanium;
from 0.5 to 12 wt. % water;
less than or equal to 4 wt. % carbon; and
a bound alkali metal; wherein:
a molar ratio of the bound alkali metal to the titanium is from 0.05:1 to 3:1; and/or
an amount of the bound alkali metal is in a range from 0.04 to 2 mmol of the bound alkali metal per gram of the silica.
2 . The support of claim 1 , wherein the support comprises less than or equal to 2 wt. % carbon.
3 . The support of claim 1 , wherein:
the molar ratio of the bound alkali metal to the titanium is from 0.05:1 to 3:1; and
the amount of the bound alkali metal is in a range from 0.04 to 2 mmol of the bound alkali metal per gram of the silica.
4 . The support of claim 1 , wherein bound alkali metal comprises bound sodium.
5 . The support of claim 4 , wherein:
at least a portion of the bound sodium is bound to the titanium; and/or
at least a portion of the bound sodium is present as sodium titanate.
6 . A titanated chromium/silica pre-catalyst comprising:
the titanated silica support of claim 1 ; and
from 0.1 to 5 wt. % chromium.
7 . The pre-catalyst of claim 6 , wherein at least 75 wt. % of the chromium is present in an oxidation state of three or less.
8 . The pre-catalyst of claim 6 , wherein the pre-catalyst further comprises from 0.01 to 1.5 wt. % nitrogen (N).
9 - 22 . (canceled)
23 . The support of claim 1 , wherein the molar ratio of the bound alkali metal to the titanium is from 0.12:1 to 2.2:1.
24 . The support of claim 23 , wherein the titanated silica support comprises from 1 to 6 wt. % titanium.
25 . The support of claim 24 , wherein the bound alkali metal comprises bound sodium.
26 . The support of claim 25 , wherein the molar ratio of the bound sodium to the titanium is from 0.2:1 to 1.8:1.
27 . The support of claim 1 , wherein the amount of the bound alkali metal is in a range from 0.1 to 1.2 mmol of the bound alkali metal per gram of the silica.
28 . The support of claim 27 , wherein the titanated silica support comprises from 1 to 6 wt. % titanium.
29 . The support of claim 28 , wherein the bound alkali metal comprises bound sodium.
30 . The support of claim 29 , wherein the amount of the bound sodium is in a range from 0.15 to 0.9 mmol of the bound sodium per gram of the silica.
31 . The pre-catalyst of claim 6 , wherein the molar ratio of the bound alkali metal to the titanium is from 0.12:1 to 2.2:1.
32 . The pre-catalyst of claim 31 , wherein the pre-catalyst comprises:
from 1 to 6 wt. % titanium; and
from 0.4 to 2 wt. % chromium.
33 . The pre-catalyst of claim 32 , wherein the bound alkali metal comprises bound sodium.
34 . The pre-catalyst of claim 33 , wherein the molar ratio of the bound sodium to the titanium is from 0.2:1 to 1.8:1.
35 . The pre-catalyst of claim 6 , wherein the amount of the bound alkali metal is in a range from 0.1 to 1.2 mmol of the bound alkali metal per gram of the silica.
36 . The pre-catalyst of claim 35 , wherein the pre-catalyst comprises:
from 1 to 6 wt. % titanium; and
from 0.4 to 2 wt. % chromium.
37 . The pre-catalyst of claim 36 , wherein the bound alkali metal comprises bound sodium.
38 . The pre-catalyst of claim 37 , wherein the amount of the bound sodium is in a range from 0.15 to 0.9 mmol of the bound sodium per gram of the silica.