METHODS OF PREPARING A CATALYST.

Abstract

A method comprising a) calcining a silica support at a temperature in the range of about 100 °C to about 500 °C to form a precalcined silica support, b) contacting the precalcined silica support with a titanium alkoxide to form a titanium-containing support, c) contacting the titanium-containing support with a polyol after b) to form a polyol-associated titanium-containing support (PATS), d) contacting at least one of the silica support, precalcined silica support, titanium-containing support, PATS, or combinations thereof with a chromium-containing compound to form a polymerization catalyst precursor, e) drying the polymerization catalyst precursor to form a dry polymerization catalyst precursor, and f) calcining the dry polymerization catalyst precursor to produce a polymerization catalyst, wherein less than about 0.1% by weight of a highly reactive volatile organic compound (HRVOC) during the calcination of the dry polymerization catalyst precursor.

Description

METHODS OF PREPARING A CATALYST TECHNICAL FIELD This disclosure relates to catalyst compositions. More specifically, this disclosure relates to methods for preparing olefin polymerization catalyst compositions. BACKGROUND OF THE INVENTION Improvements in the preparation methods for olefin polymerization catalysts can reduce the costs associated with catalyst production and improve process profitability. For example, during catalyst production, materials such as highly reactive volatile organic compounds (HRVOCs) can be emitted. HRVOCs play a role in ozone formation in non-ozone-producing areas, that is, areas that do not meet the Environmental Protection Agency's air quality standards for ground-level ozone. Consequently, processes that result in HRVOC production may depend on compliance with various state and federal regulations regarding HRVOC emissions, such as the HRVOC Emissions Cap and Trade (HECT) program. Therefore, the need persists to develop improved catalyst production processes that result in reduced HRVOC emissions. SUMMARY OF THE INVENTION A method comprising a) calcining a silica support at a temperature in the range of about 100 °C to about 500 °C to form a precalcined silica support, b) contacting the precalcined silica support with a titanium alkoxide to form a titanium-containing support, c) contacting the titanium-containing support with a polyol after b) to form a polyol-associated titanium-containing support (PATS), d) contacting at least one of the silica support, precalcined silica support, titanium-containing support, PATS, or combinations thereof with a chromium-containing compound to form a polymerization catalyst precursor, e) drying the polymerization catalyst precursor to form a dry polymerization catalyst precursor, and f) calcining the dry polymerization catalyst precursor to produce a polymerization catalyst, wherein less than about 0.1% by weight of a highly reactive volatile organic compound (HRVOC) during the calcination of the dry polymerization catalyst precursor. A method comprising a) calcining a silica support at a temperature in the range of about 100 °C to about 500 °C to form a precalcined silica support, b) contacting the precalcined silica support with a titanium alkoxide to form a titanium support, c) contacting the titanium support with a polyol after b) to form a polyol-associated titanium support (PATS), d) contacting PATS with a chromium-containing compound to form a polymerization catalyst precursor, e) drying the polymerization catalyst precursor to form a dry polymerization catalyst precursor, and f) calcining the dry polymerization catalyst precursor to produce a polymerization catalyst, wherein less than about 0.1 wt% of a highly reactive volatile organic compound (HRVOC) is emitted during the calcination of the dry polymerization catalyst precursor. A method comprising a) calcining a silica support at a temperature in the range of about 100 °C to about 500 °C to form a precalcined silica support, b) contacting the precalcined silica support with a chromium-containing compound to form a silica / Cr support, c) contacting the silica / Cr support with a titanium alkoxide to form a titanium-containing support, d) after c), contacting the titanium-containing support with a polyol to form a polymerization catalyst precursor, e) drying the polymerization catalyst precursor to form a dry polymerization catalyst precursor, and f) calcining the dry polymerization catalyst precursor to produce a polymerization catalyst, wherein less than about 0.1 wt% of a highly reactive volatile organic compound (HRVOC) is emitted during the calcination of the dry polymerization catalyst precursor. A method comprising a) calcining a silica support at a temperature in the range of about 100 °C to about 500 °C to form a precalcined silica support, b) contacting the precalcined silica support with a titanium alkoxide to form a titanium support, c) contacting the titanium support with a chromium-containing compound to form a Cr / Ti support, d) after c) contacting the Cr / Ti support with a polyol to form a polymerization catalyst precursor, e) drying the polymerization catalyst precursor to form a dry polymerization catalyst precursor, and f) calcining the dry polymerization catalyst precursor to produce a polymerization catalyst, wherein less than about 0.1 wt% of a highly reactive volatile organic compound (HRVOC) is emitted during the calcination of the dry polymerization catalyst precursor. A method comprising a) calcining a silica / Cr support at a temperature in the range of about 100 °C to about 500 °C to form a precalcined support, b) contacting the precalcined support with a titanium alkoxide to form a titanium-containing support, c) contacting the titanium-containing support with a polyol after b) to form a polyol-associated titanium-containing support (PATS), d) drying the PATS to form a dry polymerization catalyst precursor, and e) calcining the dry polymerization catalyst precursor to produce a polymerization catalyst, wherein less than about 0.1 wt% of a highly reactive volatile organic compound (HRVOC) is emitted during the calcination of the dry polymerization catalyst precursor. zLLenn / Lznz / E / Yii BRIEF DESCRIPTION OF THE FIGURES Figures 1-5 are mass and thermogravimetric spectra for the samples in Example 2. DETAILED DESCRIPTION OF THE INVENTION This paper discloses methods for preparing a polymerization catalyst. In one embodiment, the method comprises combining a silica support material and a titanium-containing compound to form a titanium support, and then contacting the titanium support with a polyol to form a polyol-associated titanium support (PATS). Chromium can be added to the support (e.g., the PATS) at any suitable time during the method by contacting the support with a chromium-containing compound, thereby producing a polymerization catalyst precursor. The polymerization catalyst precursor can be heat-treated, and during heat treatment, the amount of HRVOCs emitted can be less than the amount emitted during heat treatment of an otherwise similar material formed in the absence of a polyol.The methodologies disclosed herein produce a catalyst whose preparation results in reduced HRVOC emissions and are referred to herein as reduced emission catalysts (RECs). This document describes in more detail various method sequences specifically designed to contact the catalyst components and produce PATSs and / or RECs. In one embodiment, a silica support material (e.g., silica support) suitable for use in this disclosure may have a surface area and pore volume effective for providing for the production of an active catalyst (e.g., an REC). In one embodiment, the silica support material has a surface area in the range of about 10 m² / gram to about 1000 m² / gram, alternatively, about 100 m² / gram to about 700 m² / gram, alternatively, about 200 m² / gram to about 600 m² / gram, or alternatively, about 250 m² / gram to about 550 m² / gram. The silica support material can also be characterized by a pore volume of more than around 0.5 cm3 / gram, alternatively, more than around 0.9 cm3 / gram, alternatively, more than around 1.1 cm3 / gram, or alternatively, more than around 1.5 cm3 / gram.In one embodiment, the silica support material is characterized by a pore volume ranging from approximately 0.5 cm³ / gram to approximately 1.5 cm³ / gram. The silica support material can also be characterized by an average particle size ranging from approximately 10 microns to approximately 500 microns, alternatively from approximately 25 microns to approximately 300 microns, or alternatively from approximately 40 microns to approximately 150 microns. Generally, the average pore size of the silica support material ranges from approximately 10 Angstroms to approximately 1000 Angstroms. In one modality, the average pore size of the silica support material is in the range of around 50 Angstroms to around 500 Angstroms, while in yet another modality the average pore size varies from around 75 Angstroms to around 350 Angstroms. The silica support material may contain more than approximately 50 percent silica, or alternatively, more than approximately 80 percent silica, or alternatively, more than approximately 90 percent silica by weight of the silica support material. The silica support material may be prepared by any suitable method; for example, the silica support material may be prepared synthetically by hydrolysis of tetrachlorosilane (SiCU) with water or by contacting sodium silicate with a mineral acid. An example of silica support material suitable for use in this disclosure includes, but is not limited to, ES70, which is a silica support material with a surface area of ​​300 m² / g and a pore volume of 1.6 cc / g that is commercially available from PQ Corporation.The silica support material may include additional components that do not adversely affect the REC, such as zirconium oxide, alumina, thorium dioxide, magnesium oxide, fluoride, sulfate, phosphate, or mixtures thereof. The silica support material may be present in the REC in an amount of approximately 50 wt% to approximately 99 wt%, or alternatively, from approximately 80 wt% to approximately 99 wt%. In this case, the support percentage refers to the final weight percentage of support associated with the catalyst relative to the total weight of the catalyst after all processing steps. In one embodiment, the titanium-containing compound comprises a compound containing tetravalent titanium (T₄⁺). The compound containing T₄⁺ can be any compound comprising tetravalent titanium; alternatively, the compound containing T₄⁺ can be any compound soluble in aqueous solution and capable of releasing a T₄⁺ species in solution. In one embodiment, the titanium-containing compound is an organotitanium compound containing at least one alkoxide. Alternatively, the titanium-containing compound comprises a titanium tetraalkoxide. In one embodiment, the titanium alkoxide is titanium isopropoxide Ti(O₄Pr)₄, titanium ethoxide Ti(OEt)₄, titanium n-propoxide Ti(nOPr)₄, titanium butoxide Ti(OBu)₄, titanium 2-ethylhexoxide, or combinations thereof. The amount of titanium present in the REC can vary from approximately 0.1 wt% to approximately 10 wt% of titanium in the REC, or alternatively, from approximately 0.5 wt% to approximately 5 wt% of titanium, or alternatively, from approximately 0.1 wt% to approximately 4 wt%, or alternatively, from approximately 2 wt% to approximately 4 wt%. In this case, the percentage of titanium refers to the final weight percentage of titanium associated with the catalyst composition in the total weight of the catalyst composition after all processing stages. In several embodiments, the silica support material and the titanium-containing compound are pre-contacted in the absence of a polyhydric alcohol (e.g., a polyalcohol or polyol) to form a titanium support, and subsequently the polyol is brought into contact with the titanium support. In some embodiments, the polyol may comprise any hydrocarbon with at least two alcohol groups (or, alternatively, referred to as hydroxy groups), alternatively at least three alcohol groups, or alternatively at least four alcohol groups. In one embodiment, the polyol is an aliphatic hydrocarbon comprising at least two alcohol groups. In some embodiments, the polyol is a glycol, a sugar, a reducing sugar, an oligomer of a glycol, or combinations thereof. In one respect, the polyol can be an aliphatic polyol, such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, tripropylene glycol, polyethylene glycols with a molecular weight of 106 to 8500, polyethylene glycols with a molecular weight of 400 to 2000, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,2-hexanediol, 1,6-hexanediol, 1,2-octanediol, 1,8-octanediol, 1,2-decanediol, 1,10-decanediol, glycerol, 2,2-dimethylolpropane, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol, 1,2,4-butanetriol, 2,2,4-trimethyl-1,3-pentanediol or combinations thereof. In one respect, the polyol can be a cyclic aliphatic polyol, such as 1,2-cyclopentanediol, 1,3-cyclopentanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, bis(4-hydroxycyclohexyl)methane, 2,2-bis(4-hydroxycyclohexyl)propane, or any combination of these. In one respect, the polyol can be an aralkyl polyol, such as 1-phenyl-1,2-ethanediol, 1,2-benzenedimethanol, 1,3-benzen-di-methanol, 1,4-benzen-di-methanol, or mixtures of these. In one respect, the polyol can be an aromatic polyol, such as 1,2-benzenediol (pyrocatechol), 1,3-benzenediol (resorcinol), 1,4-benzenediol, methylcatechol, methyl resorcinol, 1,2,4-benzenetriol, 2-hydroxybenzyl alcohol, 3-hydroxybenzyl alcohol, 4-hydroxybenzyl alcohol, 3,5-dihydroxybenzyl alcohol, 2-(2-hydroxyphenyl)ethanol, 2-(3-hydroxyphenyl)ethanol, 2-(4-hydroxyphenyl)ethanol, 2-phenyl-1,2-propanediol, or mixtures of these. In one sense, a polyol is a sugar alcohol that refers to the hydrogenated forms of the aldoses or ketoses of a sugar. For example, glucitol, also known as sorbitol, has the same linear structure as the glucose chain, but the aldehyde group (-CHO) is replaced with a -CH2OH group. Other common sugar alcohols include the monosaccharides erythritol and xylitol, and the disaccharides lactitol and maltitol. In general, sugar alcohols can be characterized by the general formula HO-CH2-(CH-OH)n-CH2-OH, where n is usually from 1 to 2. For example, when n = 2, the sugar alcohol can be erythritol, threitol, etc. For example, when n = 3, the sugar alcohol can be arabitol, xylitol, ribitol, etc. For example, when n = 4, the sugar alcohol can be mannitol, sorbitol, etc. The most common sugar alcohols have 5 or 6 carbon atoms in their structure, where n is 3 or 4, respectively. In one embodiment, the sugar alcohol comprises mannitol, sorbitol, arabitol, threitol, xylitol, ribitol, galactitol, fruitol, iditol, inositol, volemitol, isosomal, maltitol, lactitol or combinations thereof. In one embodiment, the polyol comprises ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, tripropylene glycol, polyethylene glycols with a molecular weight of 106 to 1000, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,2-hexanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-octanediol, 1,8-octanediol, 1,2-decanediol, 1,10-decanediol, glycerol, 2,2-dimethylolpropane, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol, 1,2,4-butanediol, 2,2,4trimethyl-1,3-pentanediol, 1-phenyl-1,2-ethanediol, 1,2-benzenediol (pyrocatechol), 1,3-benzenediol (resorcinol), 1,4-benzenediol, methylcatechol, methylresorcinol, 1,2,4-benzenetriol, 2-hydroxybenzyl alcohol, 3-hydroxybenzyl alcohol, 4-hydroxybenzyl alcohol, 3,5-dihydroxybenzyl alcohol, 1,2-benzenedimethanol, 1,3-benzenedimethanol, 1,4-benzenedimethanol, 2-(2-hydroxyphenyl)ethanol, 2-(3-hydroxyphenyl)ethanol, 2-(4-hydroxyphenyl)ethanol, 2-phenyl-1,2-propanediol, bisphenol A (2,2-di(4-hydroxyphenyl)propane), bisphenol F (bis(4-hydroxyphenyl)methane), bisphenol S (4,4'-dihydroxydiphenylsulfone), bisphenol Z (4,4'-cyclohexyldenobisphenol), bis(2-hydroxyphenyl)methane, or combinations thereof. In one embodiment, the polyol is selected from the group consisting of ethylene glycol, glycerol, propylene glycol, butane glycol, lactic acid, or combinations thereof. In one embodiment, the polyol is present in a sufficient amount to provide from about 0.1 to about 10 molar equivalents of polyol per mole of titanium, alternatively from about 0.5 to about 5, alternatively from about 1 to about 4, or alternatively from about 2 to about 4. In several embodiments, chromium can be added to the support (to produce a chromium-containing REC) by contacting the silica support material with one or more chromium-containing compounds. The chromium-containing compound can be a water-soluble compound or a hydrocarbon-soluble compound. Examples of water-soluble chromium compounds include chromium trioxide, chromium acetate, chromium nitrate, or combinations thereof. Examples of hydrocarbon-soluble chromium compounds include tert-butyl chromate, a diarene chromium(0) compound, biscyclopentadienyl chromium(II), chromium(III) acetylacetonate, or combinations thereof. In one embodiment, the chromium-containing compound can be a chromium(II) compound, a chromium(III) compound, or combinations thereof.Suitable chromium(III) compounds include, but are not limited to, chromium carboxylates, chromium naphthenates, chromium halides, chromium sulfate, chromium nitrate, chromium dionates, or combinations thereof. Specific chromium(III) compounds include, but are not limited to, chromium(III) sulfate, chromium(III) chloride, chromium(III) nitrate, chromium bromide, chromium(III) acetylacetonate, and chromium(III) acetate. Suitable chromium(II) compounds include, but are not limited to, chromium chloride, chromium bromide, chromium iodide, chromium(II) sulfate, chromium(II) acetate, or combinations thereof. The amount of chromium present in the catalyst can vary from approximately 0.1% by weight to approximately 10% by weight of the REO, or alternatively, from approximately 0.25% by weight to approximately 3% by weight, or alternatively, from approximately 0.5% by weight to approximately 1.5% by weight. In this case, the percentage of chromium refers to the final percentage of chromium associated with the support material by weight of the total material after all processing stages. In one embodiment, a method for preparing an REC of the type described herein comprises contacting the silica support material with a titanium-containing compound to form a titanium-containing support before contacting the titanium-containing support with a polyol. Chromium may be added at any suitable time or stage of the method when contacting the support with a chromium-containing compound. The silica support material may be used as prepared or as obtained from commercial sources. Alternatively, the silica support material may be calcined prior to use in the preparation of an REC (e.g., before contacting any of the other catalyst components, such as titanium alkoxide, polyol, and / or a chromium-containing compound).For example, silica support material can be calcined at a temperature of approximately 100°C to approximately 500°C, or alternatively, from approximately 125°C to approximately 300°C, or alternatively, from approximately 150°C to approximately 200°C for a period of time of approximately 30 minutes to approximately 24 hours, or alternatively, from approximately 1 hour to approximately 12 hours, or alternatively, from approximately 1 hour to approximately 8 hours to produce precalcined silica support material. Hereafter, this disclosure will refer to the use of precalcined silica support material, although it should be understood that the silica support material may or may not have undergone a precalcination process of the type described herein. In one embodiment, the silica support material is contacted with a titanium-containing compound, both of the type described herein, to produce a titanium-containing silica support. The contact can be carried out by any suitable method, for example, through ion exchange, incipient moisture, pore filling, aqueous impregnation, organic solvent impregnation, melt coating, co-gelation, and the like. The titanium-containing silica support material can then be contacted with a polyol (for example, ethylene glycol) to produce a polyol-associated titanium-containing silica support (PATS). Contacting the titanium-containing silica support material with the polyol can be carried out in the presence of any suitable solvent. For example, the solvent can be an anhydrous organic solvent.In one embodiment, the solvent comprises alcohols, ketones, aliphatic hydrocarbons, aromatic hydrocarbons, halocarbons, ethers, acetonitrile, esters, or combinations thereof. Alternatively, the solvent comprises alcohols, ketones, esters, or combinations thereof. zLLenn / Lznz / E / Yii Aliphatic hydrocarbons that may be useful as solvents include aliphatic hydrocarbons C3 to C20, alternatively, aliphatic hydrocarbons C4 to C15 or, alternatively, aliphatic hydrocarbons C5 to C10. Aliphatic hydrocarbons may be cyclic or acyclic and / or may be linear or branched, unless otherwise specified.Non-exhaustive examples of suitable acyclic aliphatic hydrocarbon solvents that can be used alone or in any combination include propane, isobutane, n-butane, butane (n-butane or a mixture of linear and branched C4 acyclic aliphatic hydrocarbons), pentane (n-pentane or a mixture of linear and branched C5 acyclic aliphatic hydrocarbons), hexane (n-hexane or a mixture of linear and branched C5 acyclic aliphatic hydrocarbons), heptane (n-heptane or a mixture of linear and branched C7 acyclic aliphatic hydrocarbons), octane (n-octane or a mixture of linear and branched C7 acyclic aliphatic hydrocarbons), and combinations thereof. Aromatic hydrocarbons that may be useful as solvents include aromatic hydrocarbons Ce to C20 or, alternatively, aromatic hydrocarbons Ce to C10.Non-exhaustive examples of suitable aromatic hydrocarbons that may be used alone or in any combination in this disclosure include benzene, toluene, xylene (which includes ortho-xylene, meta-xylene, para-xylene, or mixtures thereof), and ethylbenzene, or combinations thereof. Halogenated aliphatic hydrocarbons that may be useful as solvents include C1 to C15 halogenated aliphatic hydrocarbons, or alternatively, C1 to C10 halogenated aliphatic hydrocarbons or, alternatively, C1 to C5 halogenated aliphatic hydrocarbons. Halogenated aliphatic hydrocarbons may be cyclic or acyclic and / or linear or branched, unless otherwise specified. Non-exhaustive examples of suitable halogenated aliphatic hydrocarbons that may be used include methylene chloride, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, and combinations thereof; or alternatively, methylene chloride, chloroform, dichloroethane, trichloroethane, and combinations thereof. Halogenated aromatic hydrocarbons that may be useful as solvents include halogenated aromatic hydrocarbons Ce to C20 or, alternatively, halogenated aromatic hydrocarbons Ce to C10.Non-exhaustive examples of suitable halogenated aromatic hydrocarbons include chlorobenzene, dichlorobenzene, and combinations thereof. Esters, ketones, or alcohols that can be useful as solvents include C1 to C20 esters, ketones, or alcohols; alternatively, C1 to C10 esters, ketones, aldehydes, or alcohols; or alternatively, C1 to C5 esters, ketones, aldehydes, or alcohols. Non-exhaustive examples of suitable esters that can be used as solvents include ethyl acetate, propyl acetate, butyl acetate, isobutyl isobutyrate, methyl lactate, ethyl lactate, and combinations thereof. Non-exhaustive examples of suitable ketones that can be used as solvents include acetone, ethyl methyl ketone, methyl isobutyl ketone, and combinations thereof. Non-exhaustive examples of suitable alcohols that can be used as solvents include methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, pentanol, hexanol, heptanol, octanol, benzyl alcohol, phenol, cyclohexanol and the like, or combinations thereof.In one embodiment, the solvent comprises methanol, ethanol, isopropanol, propanol, butanol, acetone, methyl ethyl ketone, ethyl acetate, heptane, or combinations thereof. In one embodiment, the method further comprises drying the PATS. For example, the PATS can be dried at a temperature of about 40 °C to about 300 °C, alternatively, from about 80 °C to about 200 °C, or alternatively, from about 100 °C to about 200 °C for a period of time from about 30 minutes to about 24 hours, or alternatively, from about 1 hour to about 12 hours to form a dry PATS. In one embodiment, the dry PATS is subsequently contacted with the chromium-containing compound to form a chromium-containing PATS. Contacting the dry PATS with the chromium-containing compound can be carried out using any suitable method, such as, for example, incipient moisture impregnation. In one embodiment, the chromium-containing PATS (e.g., catalyst precursor) is activated to form the REO.In alternative embodiments, chromium can be added to the support (and the resulting catalyst, e.g., a polymerization catalyst) at any suitable point in the overall catalyst production process. For example, in alternative embodiments, chromium can be added by placing at least one of a silica support, a precalcined silica support, a titanium support, a PATS, or combinations thereof, in contact with a chromium-containing compound. In some embodiments, a method for forming a REO comprises contacting a precalcined silica support material with a chromium-containing compound to form a chromium-containing silica support material. The resulting chromium-containing silica support material can then be contacted with a titanium-containing compound to form a Cr / Ti / Si material. The Cr / Ti / Si material can be dried to form a dry Cr / Ti / Si material under conditions similar to those described herein for drying a PATS. The dry Cr / Ti / Si material can be contacted with a polyol in the presence of a solvent to form a chromium-containing PATS (e.g., a catalyst precursor), which can then be activated to form a REC. In one embodiment, a methodology for forming a REC comprises contacting the titanium-containing compound and the silica support material before adding a polyol. In one embodiment, the chromium-containing PATS is heat-treated (e.g., calcined) to form a REC. The heat treatment of the chromium-containing PATS can be carried out by any suitable method, e.g., fluidization. Without intending to be limited to theory, the heat treatment of the chromium-containing support may result in an increase in the amount of hexavalent chromium present in the catalyst. In one embodiment, the heat treatment of the chromium-containing PATS is carried out in any suitable atmosphere, such as air, oxygen, inert gases (e.g., Ar), or carbon monoxide, by heating to a temperature of approximately 400 °C to approximately 1000 °C, alternatively, from approximately 500 °C to approximately 900 °C, alternatively, from approximately 550 °C to approximately 850 °C, or alternatively, from approximately 550 °C to approximately 750 °C.Heat treatment can be carried out for a period of time ranging from about 30 minutes to about 24 hours, alternatively from about 1 hour to about 12 hours, or alternatively from about 4 hours to about 8 hours. In one embodiment, one or more of the steps described above for the preparation of an REO can be carried out in a reactor or reactor system. In an alternative embodiment, one or more of the steps described above for the preparation of an REO can be carried out outside of a reactor or reactor system. In such embodiments, one or more preparation parameters (e.g., heat treatment of the chromium-containing PATS) can be adjusted to facilitate the formation of the REO. The resulting material is an REO that can function as a polymerization catalyst when used in a polymerization system or reaction. The catalysts of this disclosure (i.e., REO) are suitable for use in any olefin polymerization method with different types of polymerization reactors. In one embodiment, a polymer of this disclosure is produced by any olefin polymerization method with different types of polymerization reactors. As used herein, "polymerization reactor" includes any reactor capable of polymerizing olefin monomers to produce homopolymers and / or copolymers. The homopolymers and / or copolymers produced in the reactor may be referred to as resins and / or polymers. The various types of reactors include, but are not limited to, those that may be referred to as batch, slurry, gas-phase, solution, high-pressure, tubular, autoclave, or other reactors. Gas-phase reactors may include fluidized bed reactors or horizontal reactors.Suspension reactors may comprise vertical and / or horizontal loops. High-pressure reactors may comprise tubular reactors and / or autoclaves. Reactor types may include continuous and / or batch processes. Continuous processes may employ continuous and / or intermittent product transfer or discharge. Processes may also include the total or partial direct recycling of unreacted monomers, unreacted comonomers, catalysts and / or cocatalysts, diluents, and / or other polymerization process materials. zLLenn / Lznz / E / Yii The polymerization reactor systems described herein may comprise one type of reactor in a system or multiple reactors of the same or different types operating in any suitable configuration. Polymer production in multiple reactors may include several stages in at least two independent polymerization reactors interconnected by a transfer system, making it possible to transfer the polymers produced in the first polymerization reactor to the second reactor. Alternatively, polymerization in multiple reactors may include the transfer, either manual or automatic, of the polymer from one reactor to the next reactor or reactors for further polymerization. Alternatively, multi-stage polymerization may be carried out in a single reactor in which the conditions are modified so that a different polymerization reaction occurs. The desired polymerization conditions in one of the reactors may be the same as, or different from, the operating conditions of any of the other reactors involved in the overall production process of the polymer described herein. Multiple reactor systems may include any combination, including, but not limited to, multiple loop reactors, multiple gas-phase reactors, a combination of gas-phase and loop reactors, multiple high-pressure reactors, or a combination of high-pressure reactors with loop and / or gas reactors. The multiple reactors may be used in series or in parallel. In one embodiment, any arrangement and / or any combination of reactors may be employed to produce the polymer described herein. According to one embodiment, the polymerization reactor system may comprise at least one looped suspension reactor. Such reactors are common and may comprise vertical or horizontal loops. During polymerization, monomers, diluents, catalytic systems, and optionally, comonomers can be continuously fed into a looped suspension reactor. Typically, continuous processes may involve the continuous introduction of a monomer, a catalyst, and / or a diluent into a polymerization reactor and the continuous removal from said reactor of a suspension comprising polymer particles and the diluent. The reactor effluent may be flash-vaporized to remove the liquids comprising the diluent from the comonomer, monomer, and / or solid polymer.It is possible to employ various technologies in this separation stage, including, but not limited to, flash vaporization, which may include any combination of heat addition and pressure reduction, separation by cyclonic action in either a cyclonic or hydrocyclonic separator, separation by centrifugation, or other suitable separation methods. Typical suspension polymerization processes (also known as particle-forming processes) are described, for example, in U.S. patent no. 3248 zLLenn / Lznz / E / Yii 179, 4 501 885, 5 565 175, 5 575 979, 6 239 235, 6 262 191 and 6 833 415, each of which is incorporated herein in its entirety by means of this reference. Suitable diluents used in suspension polymerization include, but are not limited to, the monomer being polymerized and hydrocarbons as liquids under reaction conditions. Examples of suitable diluents include, but are not limited to, hydrocarbons such as propane, cyclohexane, isobutane, n-butane, n-pentane, isopentane, neopentane, and n-hexane. Some loop polymerization reactions can be carried out in batches without the use of diluents. One example is the polymerization of the propylene monomer, as described in U.S. Patent No. 5,455,314, which is incorporated herein in its entirety by this reference. According to yet another embodiment, the polymerization reactor may comprise at least one gas-phase reactor. Such systems may employ a continuous recycle stream containing one or more monomers that are continuously cycled through a fluidized bed in the presence of a catalyst under polymerization conditions. A recycle stream can be withdrawn from the fluidized bed and recycled back into the reactor. Simultaneously, the polymer product can be withdrawn from the reactor and a new or unprocessed monomer added to replace the polymerized monomer. Such gas-phase reactors may comprise a multi-stage gas-phase polymerization process of olefins in which the olefins are polymerized in the gas phase in at least two independent gas-phase polymerization zones by feeding a catalyst-containing polymer formed in a first polymerization zone to a second polymerization zone.A type of gas-phase reactor is described in U.S. Patent Nos. 4,588,790, 5,352,749, and 5,436,304, each of which is incorporated herein in its entirety by reference. According to yet another embodiment, a high-pressure polymerization reactor may comprise a tubular reactor or an autoclave reactor. Tubular reactors may have several zones in which catalysts, initiators, or raw monomers are added. An inert gas stream may carry the monomer and introduce it into one zone of the reactor. Initiators, catalysts, and / or catalytic components may be carried in a gas stream and introduced into another zone of the reactor. The gas streams may be mixed during polymerization. Heat and pressure may be appropriately applied to obtain optimal polymerization reaction conditions. According to yet another embodiment, the polymerization reactor may comprise a solution polymerization reactor in which the monomer is contacted with the catalytic composition by suitable stirring or other means. A carrier comprising an organic diluent or excess monomer may be used. If desired, the monomer may be contacted with the catalytic reaction product in the vapor phase in the presence or absence of liquid material. The polymerization zone is maintained at temperatures and pressures that will generate the formation of a polymer solution in a reaction medium. Stirring may be employed to obtain better temperature control and to maintain uniform polymerization mixtures in the polymerization zone. Suitable means are employed to dissipate the exothermic heat of polymerization. The polymerization reactors suitable for this description may further comprise any combination of at least one raw material feeding system, at least one catalyst or catalytic component feeding system, and / or at least one polymer recovery system. Additionally, the reactor systems suitable for this disclosure may include systems for raw material purification, catalyst preparation and storage, extrusion, reactor cooling, polymer recovery, fractionation, recycling, storage, loading, laboratory analysis, and process control. The conditions controlled for polymerization efficiency and to provide polymeric properties include, but are not limited to, temperature, pressure, the type and amount of catalyst or cocatalyst, and the concentrations of various reactants. The polymerization temperature can affect catalytic productivity, the polymer's molecular weight, and its molecular weight distribution. According to the Gibbs free energy equation, any temperature below the depolymerization temperature can be a suitable polymerization temperature. Typically, this includes, for example, from around 60 °C to around 280 °C, and / or from around 70 °C to around 110 °C, depending on the type of polymerization reactor and / or the polymerization process. The appropriate pressures will also vary depending on the reactor and the polymerization process. Usually, the pressure for liquid-phase polymerization in a loop reactor is less than 1000 psig (6.9 MPa). The pressure for gas-phase polymerization is around 200 psig (1.4 MPa) to 500 psig (3.45 MPa). Typically, high-pressure polymerization in tubular reactors or autoclaves is carried out at around 20,000 psig (138 MPa) to 75,000 psig (518 MPa). Polymerization reactors can also be operated in a supercritical region, generally at higher pressures and temperatures. Operating above the critical point on a pressure / temperature diagram (supercritical phase) can offer advantages. It is possible to control the concentration of various reagents to produce polymers with specific physical and mechanical properties. It is also possible to modify the proposed final products formed by the polymer and the method of forming that product to determine the desired final product properties. Mechanical properties include, but are not limited to, tensile strength, flexural modulus, impact strength, deformation, stress relaxation, and hardness. Physical properties include, but are not limited to, density, molecular weight, molecular weight distribution, melting point, glass transition temperature, crystallization melting point, stereoregularity, fracture growth, short-chain branching, long-chain branching, and rheological measurements. Generally, the concentrations of monomer, comonomer, hydrogen, cocatalyst, modifiers, and electron donors are important for producing specific polymer properties. Comonomers can be used to control product density. Hydrogen can be used to control product molecular weight. Cocatalysts can be used to alkylate, remove toxic elements, and / or control molecular weight. Reducing the concentration of toxic elements is important because toxic elements can impact reactions and / or otherwise affect the properties of the polymer product. Modifiers can be used to control product properties, and electron donors can affect stereoregularity. It is possible to produce polymers, such as polyethylene homopolymers and ethylene copolymers with other monoolefins, in the manner described above using the prepared REOs as described earlier herein. It is possible to produce finished goods or end-use items using techniques known in the art, such as extrusion, blow molding, injection molding, fiber spinning, thermoforming, and casting from polymeric resins, as described herein. For example, it is possible to extrude a polymeric resin into a sheet from which an end-use item, such as a container, cup, tray, pallet, toy, or a component of another product, is produced by thermoforming. Examples of other end-use items that can be produced with polymeric resins include pipes, films, bottles, and fibers. In one embodiment, a REO prepared as disclosed herein results in a reduction of the level of HRVOCs produced during catalyst preparation. For example, HRVOCs may comprise hydrocarbons, aromatic compounds, alcohols, ketones, or combinations thereof. In one embodiment, the HRVOCs comprise alkenes and, alternatively, propylene, butene, ethylene, or combinations thereof. The RECs produced as disclosed herein can be characterized by HRVOC emissions that are reduced by approximately 50% to approximately 99% compared to the emissions of an otherwise similar catalyst prepared in the absence of a polyol.Alternatively, the HRVOC emissions from RECs prepared as disclosed herein are reduced by more than about 50%, alternatively by more than about 75%, alternatively by more than about 90%, or alternatively by more than about 99%, compared to a similar catalyst prepared in the absence of a polyol. In one embodiment, the HRVOC emissions during the preparation of RECs of the type disclosed herein are less than about 1% by weight based on the total weight of the catalyst, alternatively by less than about 0.5% by weight, or alternatively by less than about 0.1% by weight.In one embodiment, the HRVOC is propylene and the REC has emissions of around 50% by weight to around 1% by weight based on the weight percentage of titanium in the REC and alternatively, less than around 20% by weight, alternatively, less than around 10% by weight or alternatively, less than around 1% by weight. EXAMPLES The examples below are provided as specific instances of disclosure and to demonstrate the practice and its advantages. It is understood that the examples are provided for illustrative purposes and are not intended to limit in any way the descriptive report or the claims that follow. The high-load melt flow index (HLMI) of a polymer resin represents the flow rate of a molten resin through a 0.0825-inch diameter orifice when a force of 21,600 grams is applied at 190°C. HLMI values ​​are determined according to condition E of ASTM D1238. Polymerizations were carried out in 1.2 L of isobutane at 100°C and 550 psi ethylene with 5 mL of 1-hexene to a productivity of 3200 g PE / g catalyst. Catalytic activity was determined by dividing the mass of polymer recovered from the reaction by the active polymerization time. Example 1 Four catalysts were prepared, and the effects of the presence of a polyol during preparation on the catalyst properties were evaluated. Various properties of the catalysts in this disclosure, denoted as S1–S4, are compared to those of a control catalyst, denoted as CONT, prepared in the absence of a polyol, as shown in Table 1. Table 1 zLLenn / Lznz / E / Yii Catalyst Titanium Source Additive Activity HLMI Solvent CONT Ti(OiPr)4 None 5767 18.4 MeOH S1 Ti(OiPr)4 1 equiv. glycerol 5455 20.4 MeOH S2 Ti(OIPr)4 3 equiv. glycerol 6226 20.6 ¡PrOH S3 Ti(OiPr)4 3 equiv. EG 6067 18.9 ¡PrOH S4 TI(OIPr)4 3 equiv. glycerol 4695 19.9 MeOH The results demonstrate that catalysts prepared with a polyol (i.e., REC) do not appear to be significantly different in terms of polymerization activity or melt flow index potential of the polymers produced, compared to the results observed when using a control catalyst prepared in the absence of a polyol. Example 2 The HRVOC emissions of catalysts of the type described herein (REC) were evaluated. Specifically, thermogravimetric and mass spectral analyses (TGA / MS) were performed on catalysts of the type described herein prepared in the presence or absence of a polyol. Figure 1 illustrates the TGA / MS spectrum of a titanium oxide and silica / Cr catalyst prepared with Ti(O₂Pr)₄ in the absence of a polyol (CONT). Referring to Figure 1, a peak at -250 °C with mass-to-charge ratio (m / z) signals of 39, 41, and 42 indicates propylene emission. Figure 2 illustrates the TGA / MS spectrum of a commercial silica / Cr catalyst wetted with isopropanol, which from ~85°C to 165°C showed am / z peaks of 31, 39, 41, 42, 43, and 45. These results demonstrate that the signal observed in Figure 1 is due to propylene and not to the loss of isopropanol by titanium oxide bonded to silica. S1, a REC prepared in the presence of polyol glycerol, and the solvent methanol exhibited what appeared to be a significant reduction in propylene production. See Figure 3. The TGA / MS spectrum presented in Figure 3 exhibits two losses of isopropanol. The first loss occurred at around 70 °C and the second at around 130 °C. Without being limited to theory, the results suggest that the first peak is likely due to evaporation of free solvent, while the second peak appears due to the loss of isopropanol that is physically adsorbed onto the silica gel. A third, broad peak of much lower intensity occurred at around 225 °C and comprised mainly signals from m / z = 39, 41, and 42, suggesting that it was due to propylene. A second catalyst was prepared with 3 equivalents of glycerol and isopropanol as the solvent (S2). A TGA / MS spectrum of S2 (Figure 4) shows only two peaks before the combustion of the organic components: one at 145 °C corresponding to the desorption of isopropanol and another at nearly 300 °C. The latter peak comprised signals from m / z = 42, 43, and possibly 44, 45. However, the peak for OO2 present due to the combustion of the organic components supports this peak. The observed signals are consistent with glycerol, which has a boiling point of 290 °C, and nothing in the spectrum suggests the production of propylene. The results indicate that glycerol is capable of replacing isopropoxide ligands on titanium. Similar results were observed when ethylene glycol was used instead of glycerol. The addition of three equivalents of the diol to both methanol and isopropanol, samples S3 and S4, zLLenn / Lznz / E / Yii respectively, produced undetectable amounts of propylene during TGA / MS analysis. See Figure 5. In the TGA / MS spectra of the catalyst prepared in methanol, S3, isopropanol desorption is observed at around 150°C, followed by a peak at around 270°C containing m / z signals of 43 and 44 that can be attributed to ethylene glycol. However, no indications of propylene production were observed in the spectrum. Similar results were obtained when the catalyst was prepared in isopropanol. The following are listed as non-exhaustive examples: A first embodiment is a method comprising: a) calcining a silica support at a temperature in the range of about 100 °C to about 500 °C to form a precalcined silica support; b) contacting the precalcined silica support with a titanium alkoxide to form a titanium-containing support; c) contacting the titanium-containing support with a polyol after b) to form a polyol-associated titanium-containing support (PATS); d) contacting at least one of the silica support, precalcined silica support, titanium-containing support, PATS, or combinations thereof with a chromium-containing compound to form a polymerization catalyst precursor; e) drying the polymerization catalyst precursor to form a dry polymerization catalyst precursor; and f) calcining the dry polymerization catalyst precursor to produce a polymerization catalyst, wherein less than about 0.1% by weight of a highly reactive volatile organic compound (HRVOC) during the calcination of the dry polymerization catalyst precursor. A second modality is the method of the first modality wherein the polyol comprises ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, tripropylene glycol, polyethylene glycols with a molecular weight of 106 to 1000, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,2-hexanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-octanediol, 1,8-octanediol, 1,2-decanediol, 1,10-decanediol, glycerol, 2,2-dimethylolpropane, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol, 1,2,4-butanediol, 2,2,4-trimethyl-1,3-pentanediol, 1-phenyl1,2-ethanediol, 1,2-benzenediol (pyrocatechol), 1,3-benzenediol (resorcinol), 1,4-benzenediol, methylcatechol, methylresorcinol, 1,2,4-benzenetriol, 2-hydroxybenzyl alcohol, 3-hydroxybenzyl alcohol, 4-hydroxybenzyl alcohol, 3,5-dihydroxybenzyl alcohol, 1,2-benzenedimethanol, 1,3-benzenedimethanol, 1,4-benzenedimethanol, 2-(2-hydroxyphenyl)ethanol,2-(3-hydroxyphenyl)ethanol, 2(4-hydroxyphenyl)ethanol, 2-phenyl-1,2-propanediol, bisphenol A (2,2-di(4-hydroxyphenyl)propane), bisphenol F (bis(4-hydroxyphenyl)methane), bisphenol S (4,4'-dihydroxydiphenylsulfone), bisphenol Z (4,4'-cyclohexylidenebisphenol), bis(2-hydroxyphenyl)methane or combinations thereof. A third modality is the method of either of the first and second modalities, where the polyol is present in an amount of around 0.1 to zLLenn / Lznz / E / Yii around 10 molar equivalents per mole of titanium. A fourth modality is the method of any of the first to fourth modalities, where HRVOC is an alkene compound. A fifth modality is the method of the fourth modality, where the alkene compound is propylene. A sixth modality is the method of any of the first to fifth modalities, in which the HRVOC emission is reduced from about 50% to about 100% compared to the HRVOC emission from a polymerization catalyst prepared by a process similar in other respects in the absence of the polyol. A seventh modality which is the method of any of the first to the sixth modalities, wherein the titanium alkoxide is a titanium tetraalkoxide. An eighth modality which is the method of any of the first to the seventh modalities, wherein the titanium alkoxide comprises titanium isopropoxide. A ninth modality is the method of any of the first to the eighth modalities, wherein titanium alkoxide is present in an amount of about 0.1% by weight to about 10% by weight. A tenth modality is the method of any of the first through ninth modalities, in which the chromium-containing compound is added to the silica support. An eleventh embodiment is a method comprising placing the polymerization catalyst produced by the method of the first embodiment in contact with an olefin monomer in a reaction zone under conditions suitable for producing a polymer and recovering the polymer. A twelfth modality which is the method of the eleventh modality, wherein the olefin monomer comprises ethylene and the polymer comprises polyethylene. A thirteenth modality which is the method of any of the eleventh to twelfth modalities, where the reactor is a loop reactor. A fourteenth embodiment is a method comprising: a) calcining a silica support at a temperature in the range of about 100 °C to about 500 °C to form a precalcined silica support; b) contacting the precalcined silica support with a titanium alkoxide to form a titanium support; c) contacting the titanium support with a polyol after b) to form a polyol-associated titanium support (PATS); d) contacting PATS with a chromium-containing compound to form a polymerization catalyst precursor; e) drying the polymerization catalyst precursor to form a dry polymerization catalyst precursor; and f) calcining the dry polymerization catalyst precursor to produce a polymerization catalyst, wherein less than about 0.1 wt% of a highly reactive volatile organic compound (HRVOC) is emitted during the calcination of the dry polymerization catalyst precursor. zLLenn / Lznz / E / Yii A fifteenth embodiment is the method of the fourteenth embodiment wherein the polyol comprises ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, tripropylene glycol, polyethylene glycols with a molecular weight of 106 to 1000, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,2-hexanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-octanediol, 1,8-octanediol, 1,2-decanediol, 1,10-decanediol, glycerol, 2,2-dimethylolpropane, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol, 1,2,4-butanediol, 2,2,4-trimethyl-1,3-pentanediol, 1-phenyl1,2-ethanediol, 1,2-benzenediol (pyrocatechol), 1,3-benzenediol (resorcinol), 1,4-benzenediol, methylcatechol, methylresorcinol, 1,2,4-benzenetriol, 2-hydroxybenzyl alcohol, 3-hydroxybenzyl alcohol, 4-hydroxybenzyl alcohol, 3,5-dihydroxybenzyl alcohol, 1,2-benzenedimethanol, 1,3-benzenedimethanol, 1,4-benzenedimethanol, 2-(2-hydroxyphenyl)ethanol,2-(3-hydroxyphenyl)ethanol, 2(4-hydroxyphenyl)ethanol, 2-phenyl-1,2-propanediol, bisphenol A (2,2-di(4-hydroxyphenyl)propane), bisphenol F (bis(4-hydroxyphenyl)methane), bisphenol S (4,4'-dihydroxydiphenylsulfone), bisphenol Z (4,4'-cyclohexylidenebisphenol), bis(2-hydroxyphenyl)methane or combinations thereof. A sixteenth modality which is the method of either of the fourteenth and fifteenth modalities, wherein the polyol is present in an amount of about 0.1 to about 10 molar equivalents per mole of titanium. A seventeenth modality which is the method of any of the fourteenth to sixteenth modalities, wherein HRVOCs are hydrocarbons, aromatic compounds, alcohols, ketones or combinations thereof. An eighteenth modality that is the method of the seventeenth modality, where HRVOC is propylene. A nineteenth modality, which is the method of any of the fourteenth to eighteenth modalities, wherein an HRVOC emission is reduced from about 50% to about 100% compared to the HRVOC emission from a polymerization catalyst prepared by a process similar in all other respects in the absence of the polyol. A twentieth modality, which is the eighteenth modality method, in which propylene emissions range from about 50% by weight to about less than 1% by weight based on the weight percentage of titanium. A twenty-first modality which is the method of any of the fourteenth to twentieth modalities, wherein titanium isopropoxide is present in an amount of about 0.1% by weight to about 10% by weight. A twenty-second embodiment is a method comprising: a) calcining a silica support at a temperature in the range of about 100 °C to about 500 °C to form a precalcined silica support; b) contacting the precalcined silica support with a chromium-containing compound to form a silica / Cr support; c) contacting the silica / Cr support with a titanium alkoxide to form a titanium-containing support; d) contacting the titanium-containing support with a polyol, after c), to form a polymerization catalyst precursor; e) drying the polymerization catalyst precursor to form a dry polymerization catalyst precursor; and f) calcining the dry polymerization catalyst precursor to produce a polymerization catalyst, wherein less than about 0.1% by weight of a highly reactive volatile organic compound (HRVOC) during the calcination of the dry polymerization catalyst precursor. A twenty-third embodiment is a method comprising: a) calcining a silica support at a temperature in the range of about 100 °C to about 500 °C to form a precalcined silica support; b) contacting the precalcined silica support with a titanium alkoxide to form a titanium support; c) contacting the titanium support with a chromium-containing compound to form a Cr / Ti support; d) contacting the Cr / Ti support with a polyol, after c), to form a polymerization catalyst precursor; e) drying the polymerization catalyst precursor to form a dry polymerization catalyst precursor; and f) calcining the dry polymerization catalyst precursor to produce a polymerization catalyst, wherein less than about 0.1 wt% of a highly reactive volatile organic compound (HRVOC) is emitted during the calcination of the dry polymerization catalyst precursor. A twenty-fourth embodiment is a method comprising: a) calcining a silica support at a temperature in the range of about 100 °C to about 500 °C to form a precalcined support, b) contacting the precalcined support with a titanium alkoxide to form a titanium support, c) contacting the titanium support with a polyol after b) to form a polyol-associated titanium support (PATS), d) drying the PATS to form a dry polymerization catalyst precursor, and e) calcining the dry polymerization catalyst precursor to produce a polymerization catalyst, wherein less than about 0.1 wt% of a highly reactive volatile organic compound (HRVOC) is emitted during the calcination of the dry polymerization catalyst precursor. Although several embodiments have been illustrated and described, those skilled in the art may make modifications without departing from the spirit and indications of this disclosure. The embodiments described herein are merely examples and are not intended to be exhaustive. Variations and modifications of the description provided herein are possible and would fall within the scope of the description. Where numerical limitations or ranges are expressly indicated, it should be understood that such express limitations or ranges include iterative limitations or ranges of similar magnitude encompassed by the limitations or ranges expressly indicated (e.g., from about 1 to about zLLenn / Lznz / E / Yii includes 2, 3, 4, etc., more than 0.10 includes 0.11, 0.12, 0.13, etc.). The use of the term "optionally" with respect to any element of a claim is intended to mean that the element is required or, alternatively, is not required.It is intended that both alternatives be included within the scope of the claim. It should be understood that broad terms such as comprise, include, have, etc., are used to support more concise terms and expressions, such as consist, essentially consist of, substantially comprise, etc. Therefore, the foregoing description does not limit the scope of protection; rather, the scope is limited only by the claims that follow, and that scope includes all equivalents of the subject matter of the claims. Each and every claim is incorporated into the specification as a modality of the present description. The claims thus constitute a further description of the modalities of the present description and are in addition to them. The discussion of a reference in the disclosure does not imply an admission of that reference as a prior art, particularly any reference that may have a publication date later than the priority date of this application.Disclosures of all patents, patent applications and publications cited herein by reference are incorporated herein to the extent that they provide examples, procedures or other details supplementary to those set forth herein. zLLrnn / Lznz / E / Yii NOVELTY OF THE INVENTION Having described the present invention as above, it is considered novel and, therefore, the contents contained in the following are claimed as property:

Claims

1. A precatalyst composition comprising: i. a precalcined silica support, ii. a tetravalent titanium compound, iii. a polyol, and iv. a chromium-containing compound.

2. The composition according to claim 1 wherein the precalcined silica support is characterized by a surface area of ​​250 m2 / g 1000 m2 / g and a pore volume greater than 1.0 cm3 / g.

3. The composition according to claim 1 wherein the tetravalent titanium compound comprises titanium tetralkoxide.

4. The composition according to claim 3 wherein the titanium tetralkoxide comprises titanium ethoxide, titanium n-propoxide, titanium isopropoxide, titanium butoxide or combinations thereof.

5. The composition according to claim 1 wherein the tetravalent titanium compound is present in an amount from 0.1% by weight to 10% by weight based on the total weight of the composition.

6. The composition according to claim 1 wherein the polyol comprises ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, tripropylene glycol, polyethylene glycols with a molecular weight of 106 to 1000, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,2-hexanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-octanediol, 1,8-octanediol, 1,2-decanediol, 1,10-decanediol, glycerol, 2,2-dimethylolpropane, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol, 1,2,4-butanediol, 2,2,4-trimethyl-1,3-pentanediol, 1-phenyl1,2-ethanediol, 1,2-benzenediol (pyrocatechol), 1,3-benzenediol (resorcinol), 1,4-benzenediol, methylcatechol, methylresorcinol, 1,2,4-benzenetriol, 2-hydroxybenzyl alcohol, 3-hydroxybenzyl alcohol, 4-hydroxybenzyl alcohol, 3,5-dihydroxybenzyl alcohol, 1,2-benzenedimethanol, 1,3-benzenedimethanol, 1,4-benzenedimethanol, 2-(2-hydroxyphenyl)ethanol,2-(3-hydroxyphenyl)ethanol, 2(4-hydroxyphenyl)ethanol, 2-phenyl-1,2-propanediol, bisphenol A (2,2-di(4-hydroxyphenyl)propane), bisphenol F (bis(4-hydroxyphenyl)methane), bisphenol S (4,4'-dihydroxydiphenylsulfone), bisphenol Z (4,4'-cyclohexylidenebisphenol), bis(2-hydroxyphenyl)methane or combinations thereof.

7. The composition according to claim 1 wherein the polyol is present in an amount of 0.1 to 10 molar equivalents per mole of the tetravalent titanium compound. zLLenn / Lznz / E / Yii 8. The composition according to claim 1 wherein the chromium-containing compound comprises basic chromium acetate.

9. The composition according to claim 1 wherein the chromium-containing compound is present in an amount of 0.1% by weight to 10% by weight of the total weight of the composition.

10. A precatalyst composition prepared by: a. calcining a silica support at a temperature in the range of 100 °C to 500 °C to form a precalcined silica support; b. contacting the precalcined silica support in a solvent with a titanium alkoxide to form a titanium-containing support; c. contacting the titanium-containing support with a polyol after b) to form a polyol-associated titanium-containing support (PATS); and d. contacting at least one of the silica support, the precalcined silica support, the titanium-containing support, the PATS, or combinations thereof with a chromium-containing compound to form the precatalyst composition.

11. The composition according to claim 10 wherein the solvent is anhydrous.

12. The composition according to claim 11 wherein the solvent comprises alcohols, ketones, aliphatic hydrocarbons, aromatic hydrocarbons, halocarbons, ethers, acetonitrile, esters or combinations thereof.

13. A precatalyst composition comprising: i. a silica support coated with titanium oxide, ii. a polyol, iii. and iv. a chromium-containing compound, wherein the silica support coated with titanium oxide comprises a tetravalent titanium-containing compound selected from the group consisting of titanium ethoxide, titanium n-propoxide, titanium isopropoxide, titanium butoxide, or combinations thereof.

14. The composition according to claim 13 wherein the titanium oxide coated silica support is characterized by a surface area of ​​250 m2 / g 1000 m2 / g and a pore volume greater than 1.0 cm3 / g.

15. The composition according to claim 13 wherein the polyol comprises ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, tripropylene glycol, polyethylene glycols with a molecular weight of 106 to 1000, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,2-hexanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-octanediol, 1,8-octanediol, 1,2-decanediol, 1,10-decanediol, glycerol, 2,2-dimethylolpropane, trimethylolethane, trimethylolpropane, zLLenn / Lznz / E / Yii 24 pentaerythritol, dipentaerythritol, sorbitol, 1,2,4-butanediol, 2,2,4-trimethyl-1,3-pentanediol, 1-phenyl1,2-ethanediol, 1,2-benzenediol (pyrocatechol), 1,3-benzenediol (resorcinol), 1,4-benzenediol, methylcatechol, methylresorcinol, 1,2,4-benzenetriol, 2-hydroxybenzyl alcohol, 3-hydroxybenzyl alcohol, 4-hydroxybenzyl alcohol, 3,5-dihydroxybenzyl alcohol, 1,2-benzenedimethanol, 1,3-benzenedimethanol, 1,4-benzenedimethanol,2-(2-hydroxyphenyl)ethanol, 2-(3-hydroxyphenyl)ethanol, 2(4-hydroxyphenyl)ethanol, 2-phenyl-1,2-propanediol, bisphenol A (2,2-di(4-hydroxyphenyl)propane), bisphenol F (bis(4-hydroxyphenyl)methane), bisphenol S (4,4'-dihydroxydiphenylsulfone), bisphenol Z (4,4'-cyclohexylidenebisphenol), bis(2-hydroxyphenyl)methane or combinations thereof.

16. The composition according to claim 15 wherein the polyol is present in an amount of 0.1 to 10 molar equivalents per mole of the tetravalent titanium-containing compound.

17. The composition according to claim 13 wherein the chromium-containing compound comprises basic chromium acetate present in an amount of 0.1% by weight to 10% by weight of the total weight of the composition.

18. A precatalyst composition comprising: i. a silica support coated with titanium oxide, ii. a polyol, and iii. a chromium-containing compound, wherein heat treatment of the precatalyst composition produces less than 1% by weight of highly reactive volatile organic chemicals based on the total weight of the composition.

19. The composition according to claim 18 wherein the silica support coated with titanium oxide comprises a compound containing tetravalent titanium selected from the group consisting of titanium ethoxide, titanium n-propoxide, titanium isopropoxide, titanium butoxide, or combinations thereof.

20. The composition according to claim 18 wherein the highly reactive volatile organic compound comprises propylene.