Methods of preparing a catalyst

A method of preparing a catalyst comprising:

• a) contacting (i) a silica-support, (ii) an oxotitanium compound characterized by a general formula R1R2TiO wherein R1 and R2 are each independently a carboxylate, a dicarboxylate, a diketonate, an alkoxide, an ammonium salt of a dicarboxylate, an ammonium salt of a tricarboxylate or combinations thereof, (iii) a chromium-containing compound, and (iv) an optional solvent to form a first aqueous mixture comprising a pre-catalyst and a reaction media having from about 1 wt. % to about 99 wt. % water;
• and
• b) thermally treating the pre-catalyst by heating to a temperature of from about 400° C. to about 1000° C. for a time period of from about 1 minute to about 24 hours to form the catalyst.

A method of preparing a catalyst comprising:

• a) contacting (i) a silica support material comprising from about 0.1 wt. % to about 20 wt. % water, (ii) a solution comprising (1) a 2,4-pentadionate oxotitanium compound, (2) a solvent and (3) from about 0.1 wt. % to about 80 wt. % water based on the total weight of the solution and (iii) a chromium-containing compound to form a pre-catalyst wherein liquid present in (i), (ii), and (iii) comprise a reaction media;
• and
• b) thermally treating the pre-catalyst by heating to a temperature in the range of from about 500° C. to about 900° C. for a time period of from about 3 hours to about 12 hours to form a catalyst.

A pre-catalyst composition comprising:

• (i) a silica-support, (ii) an oxotitanium compound characterized by the general formula R1R2TiO wherein R1 and R2 are each independently a carboxylate, a dicarboxylate, a diketonate, an alkoxide, an ammonium salt of a dicarboxylate, an ammonium salt of a tricarboxylate or combinations thereof, and (iii) a chromium-containing compound.

A pre-catalyst prepared by a process comprising contacting (i) a silica-support, (ii) an oxotitanium compound characterized by a general formula R1R2TiO wherein R1 and R2 are each independently a carboxylate, a dicarboxylate, a diketonate, an alkoxide, an ammonium salt of a dicarboxylate, an ammonium salt of a tricarboxylate or combinations thereof, (iii) a chromium-containing compound, and (iv) an optional solvent to form a first aqueous mixture comprising the pre-catalyst and a reaction media having from about 1 wt. % to about 99 wt. % water.