Chromium-catalyzed production of alcohols from hydrocarbons
Processes for converting a hydrocarbon reactant into an alcohol compound and/or a carbonyl compound are disclosed, and these processes include the steps of forming a supported chromium catalyst comprising chromium in a hexavalent oxidation state, irradiating the hydrocarbon reactant and the supported chromium catalyst 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 hydrolyzing the reduced chromium catalyst to form a reaction product comprising the alcohol compound and/or the carbonyl compound. The supported chromium catalyst can be formed by heat treating a supported chromium precursor, contacting a chromium precursor with a solid support while heat treating, or heat treating a solid support and then contacting a chromium precursor with the solid support.
1. A process for converting a hydrocarbon reactant into an alcohol compound and/or a carbonyl compound, the process comprising:
(i) contacting a solid support with an inorganic chromate compound to form a supported chromium precursor;
(ii) heat treating the supported chromium precursor at a peak temperature from about 50° C. to about 1000° C. to form a supported chromium catalyst comprising chromium in a hexavalent oxidation state;
(iii) irradiating the hydrocarbon reactant and the supported chromium catalyst 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
(iv) hydrolyzing the reduced chromium catalyst to form a reaction product comprising the alcohol compound and/or the carbonyl compound.
2. The process of claim 1 , wherein the inorganic chromate compound comprises potassium chromate, sodium chromate, ammonium chromate, potassium dichromate, sodium dichromate, ammonium dichromate, or any combination thereof.
3. The process of claim 1 , wherein step (ii) is conducted in an oxidizing atmosphere.
4. The process of claim 1 , wherein step (ii) is conducted in an inert atmosphere.
5. The process of claim 1 , wherein the peak temperature is in a range from about 100° C. to about 500° C.
6. The process of claim 1 , wherein the peak temperature is in a range from about 50° C. to about 200° C.
7. The process of claim 1 , wherein the hydrocarbon reactant comprises a C 1 to C 36 linear, branched, or cyclic alkane compound.
8. The process of claim 1 , wherein the hydrocarbon reactant comprises methane and the alcohol compound comprises methanol.
9. The process of claim 1 , wherein the hydrocarbon reactant comprises a C 2 to C 36 olefin compound, a C 6 to C 36 aromatic compound, or any combination thereof.
10. 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; and
the reduced chromium catalyst contains chromium having an average valence of less than or equal to about 5.25.
11. The process of claim 1 , wherein the process comprises:
contacting the hydrocarbon reactant with a fluidized bed of the supported chromium catalyst, and irradiating while contacting; or
contacting the hydrocarbon reactant with a fixed bed of the supported chromium catalyst, and irradiating while contacting.
12. The process of claim 1 , wherein:
the hydrocarbon reactant and the supported chromium catalyst are irradiated with from about 50,000 to about 500,000 lux of the light beam; and
the light beam comprises wavelengths above 350 nm and below 500 nm.
13. The process of claim 1 , wherein the solid support comprises a solid oxide, a chemically-treated solid oxide, a zeolite, or a combination thereof.
14. The process of claim 1 , wherein:
the light beam is from a blue light source or a UV light source;
the reduced chromium catalyst contains chromium having an average valence of less than or equal to about 4.5; and
a molar yield of the alcohol compound and/or the carbonyl compound is from about 0.05 to about 1.8 moles of the alcohol compound and/or the carbonyl compound per mole of chromium (VI) in the supported chromium catalyst.
15. A process for converting a hydrocarbon reactant into an alcohol compound and/or a carbonyl compound, the process comprising:
(i) contacting a solid support with an inorganic chromate compound to form a supported chromium precursor, the inorganic chromate compound comprising potassium chromate, sodium chromate, potassium dichromate, sodium dichromate, or any combination thereof;
(ii) heat treating the supported chromium precursor at a peak temperature from about 50° C. to about 1000° C. to form a supported chromium catalyst comprising chromium in a hexavalent oxidation state;
(iii) irradiating the hydrocarbon reactant and the supported chromium catalyst 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
(iv) hydrolyzing the reduced chromium catalyst to form a reaction product comprising the alcohol compound and/or the carbonyl compound.
16. The process of claim 15 , wherein step (ii) is conducted in an oxidizing atmosphere.
17. The process of claim 15 , wherein step (ii) is conducted in an inert atmosphere.
18. The process of claim 15 , wherein the hydrocarbon reactant comprises a C 1 to C 36 linear, branched, or cyclic alkane compound.
19. The process of claim 18 , wherein:
the hydrocarbon reactant and the supported chromium catalyst are irradiated with from about 50,000 to about 500,000 lux of the light beam; and
the light beam comprises wavelengths above 350 nm and below 500 nm.
20. The process of claim 19 , wherein the hydrocarbon reactant comprises methane and the alcohol compound comprises methanol.