Process for preparing a catalyst consisting of a support body and a catalytically active composition applied on the surface of the support body
A process for preparing a coated catalyst in which a finely divided mixture of a multielement oxide comprising the elements Mo and V and a molybdenum oxide or a molybdenum oxide former is applied to the surface of a support body as an active composition.
1. A process for preparing a coated catalyst for counteracting deactivation of the catalyst, wherein the coated catalyst comprises a support body and a catalytically active composition, the process comprising:
preparing a finely divided mixture of
(i) at least one finely divided multielement oxide comprising elements Mo and V in a molar ration of Mo to V from 15:1 to 1:1, or comprising the elements Mo and V and in addition at least one of the two elements Te and Sb, and at least one element selected from the group consisting of Nb, Pb, Ta, W, Ti, Al, Zr, Cr, Mn, Ga, Fe, Ru, Co, Rh, Ni, Pd, Pt, La, Bi, B, Ce, Sn, Zn, Si, Na, Li, K, Mg, Ag, Au and In, and
(ii) at least one finely divided substance S selected from the group consisting of oxides of molybdenum and compounds of molybdenum selected from the group consisting of ammonium molybdate, ammonium polymolybdate, ammonium heptamolybdate tetrahydrate, molybdenum oxide hydrate, and molybdenum hydroxides from which an oxide of molybdenum is formed under an elevated temperature and molecular oxygen, wherein the oxide of molybdenum is a substance having a content of Mo and oxygen of at least 98 wt. %, and
applying the finely divided mixture as the catalytically active composition on the support body with the aid of a binder.
2. The process according to claim 1 , wherein the finely divided substance S is MoO 3 .
3. The process according to claim 1 , wherein the specific surface area O M of the finely divided substance S is ≧0.1 m 2 /g and ≦5 m 2 /g.
4. The process according to claim 1 , wherein a particle diameter d 50 of the finely divided substance S is ≧1 μm and ≦200 μm.
5. The process according to claim 1 , wherein the active composition is applied to the surface of the support body in a layer thickness from 100 to 300 μm.
6. The process according to claim 1 , wherein the active composition, based on the total amount of the finely divided multielement oxide comprising Mo and V, comprises >1 and <30% by weight of the finely divided substance S.
7. The process according to claim 1 , wherein the binder is a solution composed of from 20 to 90% by weight of water and from 10 to 80% by weight of an organic compound.
8. A catalyst obtainable by a process according to claim 1 .
9. A coated catalyst for counteracting deactivation of the catalyst, the coated catalyst comprising a support body and a catalytically active composition applied to the surface of the support body, and, optionally, one or more binder, wherein the catalytically active composition is a finely divided mixture of
(i) at least one finely divided multielement oxide comprising elements Mo and V in a molar ratio Mo:V from 15:1 to 1:1, or comprising the elements Mo and V and in addition at least one of the two elements Te and Sb and at least one element selected from the group consisting of Nb, Pb, Ta, W, Ti, Al, Zr, Cr, Mn, Ga, Fe, Ru, Co, Rh, Ni, Pd, Pt, La, Bi, B, Ce, Sn, Zn, Si, Na, Li, K, Mg, Ag, Au and In, and
(ii) at least one finely divided substance S selected from the group consisting of oxides of molybdenum and compounds of molybdenum selected from the group consisting of ammonium molybdate, ammonium polymolybdate, ammonium heptamolybdate tetrahydrate, molybdenum oxide hydrate, and molybdenum hydroxides from which an oxide of molybdenum is formed under an elevated temperature and molecular oxygen, wherein the oxide of molybdenum is a substance having a content of Mo and oxygen of at least 98 wt. %.
10. A process for heterogeneously catalyzed partial gas phase oxidation of acrolein to acrylic acid, comprising conducting the oxidation of acrolein to acrylic acid over the catalyst according to claim 8 or 9 .