Chromium-catalyzed production of diols from olefins
Processes for converting an olefin reactant into a diol compound are disclosed, and these processes include the steps of contacting the olefin reactant and a supported chromium catalyst comprising chromium in a hexavalent oxidation state to reduce at least a portion of the supported chromium catalyst to form a reduced chromium catalyst, and hydrolyzing the reduced chromium catalyst to form a reaction product comprising the diol compound. While being contacted, the olefin reactant and the supported chromium catalyst can be irradiated with a light beam at a wavelength in the UV-visible spectrum. Optionally, these processes can further comprise a step of calcining at least a portion of the reduced chromium catalyst to regenerate the supported chromium catalyst.
1. A process for converting an olefin reactant into a diol compound, the process comprising:
(i) irradiating the olefin reactant and a supported chromium catalyst comprising chromium in a hexavalent oxidation state with a light beam at a wavelength in the UV-visible spectrum to reduce at least a portion of the supported chromium catalyst to form a reduced chromium catalyst;
(ii) hydrolyzing the reduced chromium catalyst to form a reaction product comprising the diol compound; and
(iii) separating at least a portion of the olefin reactant from the reaction product, wherein the at least a portion of the olefin reactant is recycled and irradiated with the supported chromium catalyst again.
2. The process of claim 1 , wherein the olefin reactant comprises a C 2 to C 36 linear, branched, or cyclic olefin compound.
3. The process of claim 1 , wherein the olefin reactant comprises ethylene, propylene, butene, pentene, hexene, heptene, octene, decene, dodecene, tetradecene, hexadecene, octadecene, or any combination thereof.
4. The process of claim 1 , wherein the supported chromium catalyst contains from about 0.01 to about 50 wt. % of chromium, based on the weight of the supported chromium catalyst.
5. The process of claim 1 , wherein the reduced chromium catalyst contains chromium having an average valence of less than or equal to about 5.25.
6. The process of claim 1 , wherein the wavelength comprises a single wavelength or a range of wavelengths in a range from about 200 nm to about 750 nm.
7. The process of claim 1 , wherein the irradiating step is conducted at a temperature from about −100° C. to about 100° C.
8. The process of claim 1 , wherein the process comprises:
contacting the olefin reactant with a fluidized bed of the supported chromium catalyst, and irradiating while contacting; or
contacting the olefin reactant with a fixed bed of the supported chromium catalyst, and irradiating while contacting.
9. The process of claim 1 , wherein:
hydrolyzing is conducted at a temperature from about 0° C. to about 100° C.; and
hydrolyzing comprises contacting the reduced chromium catalyst with a hydrolysis agent comprising water, steam, an alcohol agent, an acid agent, an alkaline agent, or any combination thereof.
10. The process of claim 1 , wherein a conversion of the olefin reactant is at least about 10 wt. %.
11. The process of claim 1 , further comprising:
separating at least a portion of the reduced chromium catalyst from the reaction product after step (ii); and
calcining the at least a portion of the reduced chromium catalyst to regenerate the supported chromium catalyst.
12. The process of claim 1 , wherein:
the olefin reactant comprises ethylene and the diol compound comprises ethanediol;
the olefin reactant comprises propylene and the diol compound comprises propanediol;
the olefin reactant comprises 1-pentene and the diol compound comprises a pentanediol; or
the olefin reactant comprises 1-hexene and the diol compound comprises a hexanediol.
13. A process for converting an olefin reactant into a diol compound, the process comprising:
(i) irradiating the olefin reactant and a supported chromium catalyst comprising chromium in a hexavalent oxidation state with a light beam at a wavelength in the UV-visible spectrum to reduce at least a portion of the supported chromium catalyst to form a reduced chromium catalyst; and
(ii) hydrolyzing the reduced chromium catalyst to form a reaction product comprising the diol compound;
wherein a molar yield of the diol compound is from about 0.01 to about 2 moles of the diol compound per mole of chromium (VI) in the supported chromium catalyst.
14. The process of claim 13 , wherein the diol compound comprises a 1,2-diol compound.
15. The process of claim 13 , wherein:
the supported chromium catalyst contains from about 0.2 to about 10 wt. % of chromium, based on the weight of the supported chromium catalyst; and
the olefin reactant comprises ethylene, propylene, butene, pentene, hexene, heptene, octene, decene, dodecene, tetradecene, hexadecene, octadecene, or any combination thereof.
16. The process of claim 15 , wherein the molar yield of the diol compound is from about 0.05 to about 1.8 moles of the diol compound per mole of chromium (VI) in the supported chromium catalyst.