Surfactant as Titanation Ligand

Abstract

A pre-catalyst composition comprising: a) a silica support comprising silica wherein an amount of silica is in a range of from about 70 wt. % to about 95 wt. % based upon a total weight of the silica support; b) a titanium-containing compound wherein an amount of titanium is in a range of from about 0.1 wt. % to about 10 wt. % based upon the total weight of the silica support; c) a chromium-containing compound wherein an amount of chromium is in a range of from about 0.1 wt. % to about 10 wt. % based upon the total weight of the silica support; d) a surfactant wherein the surfactant comprises a non-ionic surfactant, a cationic surfactant, or a combination thereof; e) a carboxylate wherein the carboxylate comprises a multi carboxylate, an alpha-hydroxy carboxylate, or a combination thereof; and f) a solvent.

What is claimed is: 
     
         1 . A method comprising contacting a silica support with a titanium-chromium-containing solution to form a titanated-chrominated silica support, wherein the titanium-chromium-containing solution comprises a titanium compound, a chromium-containing compound, a solvent, and a surfactant, and wherein the titanium-chromium-containing solution has a pH of less than about 5.5. 
     
     
         2 . The method of  claim 1 , wherein the titanium-chromium-containing solution has a pH of from about 2.5 to less than about 5.5. 
     
     
         3 . The method of  claim 1 , wherein the silica support has silica present in a range of from about 70 wt. % to about 95 wt. % based upon a total weight of the silica support. 
     
     
         4 . The method of  claim 1 , wherein the silica support has a surface area in a range of from about 100 m 2 /gram to about 1000 m 2 /gram. 
     
     
         5 . The method of  claim 1 , wherein the silica support has a pore volume in a range of from about 1.0 cm 3 /gram to about 2.5 cm 3 /gram. 
     
     
         6 . The method of  claim 1 , wherein the silica support has an average pore size in a range of from about 10 Angstroms (Å) to about 1000 Angstroms (Å); or alternatively has an average particle size in a range of from about 10 microns to about 500 microns. 
     
     
         7 . The method of  claim 1 , wherein the silica of the silica support is selected from the group consisting of a silica xerogel, a silica hydrogel, solid silica, solid silica-alumina, and a combination thereof. 
     
     
         8 . The method of  claim 1 , wherein the titanium-containing compound has a formula Ti(OR)4, TiO(OR)2, Ti(OR)2(acac)2, or Ti(OR)2(oxal), wherein “acac” is acetylacetonate, “oxal” is oxalate, and each R independently is ethyl, isopropyl, n-propyl, isobutyl, or n-butyl. 
     
     
         9 . The method of  claim 1 , wherein the titanium-containing compound comprises a titanium (IV) compound having at least one carboxylate ligand. 
     
     
         10 . The method of  claim 9 , wherein the at least one carboxylate ligand is provided by oxalic acid, citric acid, lactic acid, tartaric acid, gluconic acid, glycolic acid, malonic acid, or combinations thereof. 
     
     
         11 . The method of  claim 9 , wherein an equivalent molar ratio of the at least one carboxylate ligand to the titanium-containing compound is in a range of from about 1 to about 4. 
     
     
         12 . The method of  claim 1 , wherein the titanium-containing compound comprises a titanium (IV) alkoxide. 
     
     
         13 . The method of  claim 12 , wherein the titanium (IV) alkoxide comprises titanium (IV) ethoxide, titanium (IV) isopropoxide, titanium (IV) n-propoxide, titanium (IV) n-butoxide, titanium (IV) 2-ethylhexoxide, or a combination thereof. 
     
     
         14 . The method of  claim 1 , wherein the titanium-containing compound comprises hydrous titania, titanium hydroxide, titanium dioxide, titanic acid, titanyl sulfate, titanium acetylacetonate, titanium oxyacetylacetonate, or a combination thereof. 
     
     
         15 . The method of  claim 1 , wherein the titanium-containing compound comprises titanium tetrachloride, titanium tetrabromide, titanium (IV) oxychloride, titanium (IV) oxybromide or a combination thereof. 
     
     
         16 . The method of  claim 1 , wherein the titanium-containing compound comprises a titanium alkoxyhalide having the general formula Ti(OR) n Q 4-n ; wherein each R independently is ethyl, isopropyl, n-propyl, isobutyl, or n-butyl; wherein Q may be a fluoride, a chloride, a bromide, an iodide, or a combination thereof, and wherein n may be an integer from 1 to 4. 
     
     
         17 . The method of  claim 1 , wherein the titanium-containing compound is present in an amount of from about 0.01 wt. % to about 10 wt. % based on the total weight of the titanium-containing solution. 
     
     
         18 . The method of  claim 1 , wherein the surfactant comprises a water-insoluble component and a water-soluble component. 
     
     
         19 . The method of  claim 1 , wherein the surfactant comprises polyalkoxylates, polyethoxylates, glucosides, a polyethoxylated alcohol, a polyethoxylated mercaptan, or combinations thereof. 
     
     
         20 . The method of  claim 1 , wherein the surfactant comprises alkyl sulfates, aryl sulfates, alkylaryl sulfates, alkyl sulfonates, aryl sulfonates, alkylaryl sulfonates, phosphates of alkali metals, ammonium salts of phosphates, alkylsulfonic acids, sulfosuccinate salts, fatty acid salts, ethoxylated alcohols, amphiphilic copolymers or a combination thereof. 
     
     
         21 . The method of  claim 1 , wherein the solvent is selected from the group consisting of water, alcohol, and a combination thereof. 
     
     
         22 . The method of  claim 21 , wherein the alcohol comprises methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, pentanol, hexanol, cyclohexanol, heptanol, octanol, benzyl alcohol, phenol, or a combination thereof. 
     
     
         23 . The method of  claim 1 , further comprising heating the titanated-chrominated silica support in a reducing environment to a temperature in the range of from about 400° C. to about 1000° C. to form a polymerization catalyst.