Cobalt catalyst comprising a support containing a mixed oxide phase including cobalt and/or nickel produced using a hydrocarbon compound
The invention relates to a catalyst containing an active cobalt phase, deposited on a support comprising alumina, silica or silica-alumina, said support also containing a mixed oxide phase containing cobalt and/or nickel, said catalyst having been prepared by introducing at least one hydrocarbon organic compound of formula C x H y . The invention also relates to the use thereof in the field of Fischer-Tropsch synthesis processes.
1. A catalyst comprising an active phase consisting of cobalt, deposited on a support consisting of silica-alumina and a mixed oxide phase of cobalt, said catalyst being prepared by a process comprising at least:
a) contacting a support comprising silica-alumina with at least one solution comprising at least one precursor of cobalt, then drying and calcining at a temperature of 700 to 1200° C., so as to obtain a mixed oxide phase comprising cobalt in the support, then
b) contacting said support containing said mixed oxide phase with at least one solution comprising at least one precursor of cobalt,
c) contacting said support containing said mixed oxide phase with a solution containing at least one liquid hydrocarbon organic compound of formula C x H y , and when the solution comprises a solvent, said hydrocarbon organic compound is miscible in the solvent,
b) and c) being performed separately, in any order, or at the same time, then
d) drying at a temperature below 200° C.
2. The catalyst as claimed in claim 1 , wherein the content of mixed oxide phase in the support is between 0.1 and 50% by weight relative to the weight of the support.
3. The catalyst as claimed in claim 1 , wherein the mixed oxide phase comprises an aluminate of formula CoAl 2 O 4 .
4. The catalyst as claimed in claim 1 , wherein the mixed oxide phase comprises a silicate of formula Co 2 SiO 4 .
5. The catalyst as claimed in claim 1 , wherein the silica content of said support is between 0.5% by weight and 30% by weight relative to the weight of the support before the formation of the mixed oxide phase.
6. The catalyst as claimed in claim 1 , wherein the hydrocarbon organic compound of formula CxHy introduced during c) is an acyclic or cyclic, saturated or unsaturated hydrocarbon compound with x≥5 and y≥6.
7. The catalyst as claimed in claim 6 , wherein the hydrocarbon organic compound of formula C x H y is n-heptane, n-octane, n-nonane, n-decane, i-heptane, i-octane, i-nonane, i-decane, cyclopentane, cyclohexane, heptene, octene, nonene, decene, cyclopentadiene, cyclohexene, toluene, cumene, styrene, xylene or ethylbenzene.
8. The catalyst as claimed in claim 1 , wherein the molar ratio of hydrocarbon organic compound of formula C x H y introduced during c) relative to the cobalt element introduced in b) is between 0.01 and 5.0 mol/mol.
9. The catalyst as claimed in claim 1 , wherein the content of cobalt element introduced during b) as active phase is between 1 and 40% by weight expressed as cobalt metal element relative to the total weight of the dried catalyst.
10. The catalyst as claimed in claim 1 , wherein, after the drying in d), e) calcining is carried out at a temperature of between 200 and 550° C. in an inert atmosphere or in an oxygen-containing atmosphere.
11. The catalyst as claimed in claim 1 , wherein the catalyst obtained in the drying in d) or obtained in the calcining in e) at a temperature of between 200 and 500° C., is reduced.
12. A Fischer-Tropsch process for synthesizing hydrocarbons, wherein the catalyst as claimed in claim 1 is brought into contact with a feedstock comprising synthesis gas under a total pressure of between 0.1 and 15 MPa, under a temperature of between 150 and 350° C., and at an hourly space velocity of between 100 and 20 000 volumes of synthesis gas per volume of catalyst and per hour with an H 2 /CO molar ratio of the synthesis gas of between 0.5 and 4.
13. A process for the preparation of a catalyst comprising an active phase consisting of cobalt, deposited on a support consisting of silica-alumina and a cobalt a mixed oxide phase, said process comprising at least:
a) contacting a support comprising alumina, silica or silica-alumina with at least one solution comprising at least one precursor of cobalt, then drying and calcining at a temperature between 700 and 1200° C., so as to obtain a mixed oxide phase containing cobalt in the support, then
b) contacting said support containing said mixed oxide phase with at least one solution comprising at least one precursor of cobalt,
c) contacting said support containing said mixed oxide phase with a solution of at least one liquid hydrocarbon organic compound of formula C x H y , and when the solution comprises a solvent, said hydrocarbon organic compound is miscible in the solvent,
b) and c) being performed separately, in any order, or at the same time, then
d) drying at a temperature below 200° C.