A method of preparing a catalyst comprising a) contacting (i) a silica-support, (ii) an oxotitanium compound, (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; 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 contacting a hydrated support material comprising silica with a chromium-containing compound to form a first aqueous mixture comprising a chrominated support; contacting the first aqueous mixture comprising a chrominated support with a solution comprising (i) a solvent and (ii) an oxotitanium compound to form a second aqueous mixture comprising a pre-catalyst; and thermally treating the pre-catalyst to form the catalyst.