Spinel structured catalyst for aldehyde production
The present invention refers to a catalyst for aldehyde production, in particular formaldehyde or acetaldehyde production, through selective oxidation of alkanol, especially methanol or ethanol, with oxygen, said catalyst having a spinel structure. The catalyst typically comprises a Fe a+ q V b+ x Mo c+ y Δ z O 4 spinel structure wherein Δ is an optional cation vacancy and wherein z=3−q−x−y and q×a+x×b+y×c=8 in concentrations corresponding to 0.6<q<3, 0≦x<1.5, 0≦y≦1 and 0≦z<1.3 and 2≦a≦3, 3≦b≦5 and 3≦c≦6. The present invention further refers to a process for producing said catalyst and to the use of said catalyst for selective oxidation of alkanol, preferably methanol or ethanol, with oxygen to aldehyde, preferably formaldehyde or acetaldehyde.
1. A catalyst, comprising:
iron, oxygen, and at least metal selected from the group consisting of vanadium and molybdenum, the catalyst having a spinel sructure, the catalyst being adapted by calcination for aldehyde production through selective oxidation of alkanol with oxygen.
2. The catalyst according to claim 1 , wherein said catalyst comprises vanadium.
3. The catalyst according to claim 1 , wherein said catalyst comprises a Fe q a+ V x b+ Mo y c+ Δ z O 4 spinel structure wherein Δ is an optional cation vacancy and wherein z=3−q−x−y and q×a+x×b+y×c=8 in concentrations corresponding to 0.6<q<3, 0≦x<1.5, 0≦y≦1 and 0≦z<1.3 and 2≦a≦3, 3≦b≦5 and 3≦c≦6.
4. The catalyst according to claim 3 , wherein 1.4≦q<3.
5. The catalyst according to claim 3 , wherein 0≦x≦1.
6. The catalyst according to claim 3 , wherein 0≦y≦0.3.
7. The catalyst according to claim 3 , wherein 0≦z≦0.9.
8. The catalyst according to claim 1 , wherein said aldehyde is formaldehyde and said alkanol is methanol.
9. The catalyst according to claim 1 , wherein said aldehyde is acetaldehyde and said alkanol is ethanol.
10. The catalyst according to claim 1 , wherein said catalyst has a specific surface area (BET) of 2-25 m 2 /g.
11. The process for producing a catalyst according to claim 1 , comprising:
precipitating said catalyst from a homogenous water solution containing desired amounts of Fe, V and Mo, where said homogenous solution first is prepared from one, two or three separate water solutions, containing dissolved Fe(NO 3 ) 3 .9H 2 O, NH 4 VO 3 and (NH 4 ) 6 Mo 7 O 24 .4H 2 O, respectively, where after said precipitation is obtained by addition of a base to said homogenous solution;
separating the precipitate from said solution;
washing the precipitate;
drying the precipitate; and
calcining the precipitate at a temperature of 300 to 650° C., in an atmosphere of a reducing agent together with an oxidizing agent in one or more inert agents.
12. A method comprising contacting a catalyst according to claim 1 in a cooled multi-tube reactor for selective oxidation of alkanol, with oxygen to form an aldehyde.
13. The method according to claim 12 , wherein said alkanol is methanol and is present in concentrations of 6 to 13% and oxygen in concentrations of 8 to 15% in a gas mixture together with an inert gas, at an inlet of the reactor.
14. The method of claim 12 , wherein the alkanol is methanol or ethanol.
15. The method of claim 12 , wherein the aldehyde is formaldehyde or acetaldehyde.
16. The catalyst according to claim 1 , wherein said catalyst has a specific surface area (BET) of 3-10 m 2 /g.
17. The catalyst according to claim 1 , wherein said catalyst has a specific surface area (BET) of 4-7 m 2 /g.
18. The method according to claim 13 , where the inert gas is nitrogen.
19. The catalyst according to claim 1 , wherein said catalyst comprises molybdenum.
20. A catalyst, comprising:
iron, oxygen, vanadium and molybdenum, the catalyst having a spinel sructure, the catalyst being adapted by calcination for aldehyde production through selective oxidation of alkanol with oxygen.