Dehydrogenation catalysts
This disclosure relates to catalyst compositions including gallium and a zirconium-based mixed oxide support, to methods for making such catalysts, and to methods for dehydrogenating hydrocarbons with such catalysts. For example, in one embodiment, a catalyst composition includes a mixed oxide support comprising at least about 50 wt. % of zirconium oxide, the mixed oxide support being present in the composition in an amount within the range of about 40 wt. % to about 99.9 wt. %; and disposed on the support, gallium, present in the composition in an amount within the range of about 0.1 wt. % to about 30 wt. %, calculated as Ga 2 O 3 on a calcined basis.
1. A calcined dehydrogenation catalyst comprising a mixed oxide support comprising at least 80 wt. % to 99 wt. % of zirconium oxide and 1 wt. % to 20 wt. % of one or more of lanthanum oxide, silicon oxide and cerium oxide, the mixed oxide support being present in the composition in an amount within the range of 70 wt. % to 95 wt. %; and disposed on the support, gallium, present in the composition in an amount within the range of 7.5 wt. % to 30 wt. %, calculated as Ga 2 O 3 on a calcined basis; and one or more primary promoters selected from platinum, rhodium, palladium, and ruthenium, present in the composition in an amount within the range of 0.01 wt. % to 0.5 wt. %, calculated as oxide on a calcined basis.
2. The catalyst composition of claim 1 , wherein a platinum primary promoter is disposed on the support in an amount within the range of 0.01 wt. % to % 0.5 wt. %, calculated as PtO 2 on a calcined basis.
3. The catalyst composition of claim 1 , further comprising, disposed on the support, one or more secondary promoters selected from potassium, sodium, cesium, lithium, calcium, magnesium, strontium, and barium, present in the composition in an amount within the range of 0.01 wt. % to 2 wt. %, calculated as oxide on a calcined basis.
4. The catalyst composition of claim 1 , wherein potassium is disposed on the support in an amount within the range of 0.01 wt. % to 2 wt. %, calculated as K 2 O on a calcined basis and/or magnesium is disposed on the support in an amount within the range of 0.01 wt. % to 2 wt. %, calculated as MgO on a calcined basis.
5. The catalyst composition of claim 1 , wherein cerium is disposed on the support in an amount within the range of 0.5 wt. % to 15 wt. %, calculated as CeO 2 on a calcined basis.
6. The catalyst composition of claim 1 , wherein a total amount of oxides of zirconium, lanthanum, cerium, silicon, titanium, tungsten, and yttrium in the mixed oxide support is at least 95 wt. %.
7. The catalyst composition of claim 1 , wherein the mixed oxide support comprises less than 2 wt. % of silica.
8. The catalyst composition of claim 1 , wherein the mixed oxide support comprises less wt. % of alumina.
9. The catalyst composition of claim 1 , wherein the composition comprises the mixed oxide support, present in the composition in an amount within the range of 83.5 wt. % to 98.85 wt. %; and the primary promoter is platinum, present in the composition in an amount within the range of 0.05 wt. % to 0.5 wt. %, calculated as PtO 2 on a calcined basis.
10. The catalyst composition of claim 9 , wherein the composition further comprises a potassium secondary promoter, present in the composition in an amount within the range of 0.1 wt. % to 2 wt. % calculated as K 2 O on a calcined basis.
11. The catalyst composition of claim 1 , wherein the composition comprises less than 0.2 wt. % of chromium and less than 0.2 wt. % of iron.
12. The catalyst composition of claim 1 , wherein a total amount of the mixed oxide support, gallium oxide, the one or more primary promoters, and the one or more secondary promoters is at least 95 wt. % of the catalyst composition.
13. A method for preparing the dehydrogenation catalyst composition according to claim 1 , the method comprising providing a mixed oxide support comprising at least 50 wt. % of zirconium oxide; disposing on the mixed oxide support one or more sources of gallium and of any primary or secondary promoters and cerium to be present in the catalyst composition; and calcining the supported composition to form the dehydrogenation catalyst composition.
14. A method of dehydrogenating hydrocarbons comprising contacting a hydrocarbon feed with the dehydrogenation catalyst composition of claim 1 , wherein the hydrocarbon feed comprises one or more C 3 -C 5 alkanes, the hydrocarbon feed is contacted with the catalyst at a space velocity within the range of 0.1 h −1 to 2 h −1 -LHSV, the dehydrogenation is conducted at a temperature within the range of 400° C. to 750° C. and the dehydrogenation is conducted at a pressure within the range of 0.1 bar to 1 bar.