Solid Wacker-type catalysts (Pd-V2O5 or Pd-CeO2 supported on alumina and Pd-doped KH3PV1Mo11O40) show a marked decline in activity in the gas phase selective oxidn. of 1-butene to Me Et ketone, whereas the selectivity passes through a max. After about 5-6 h onstream, nearly steady-state behavior is reached, characterized by a slower deactivation rate and a slight decline in selectivity. The initial change in the catalytic behavior is discussed in terms of the formation of adsorbed species and changes in the valence state of V and Pd during the catalytic reaction. Both these deactivation effects can be reversed by an oxidizing treatment at 300°. The second, slow deactivation is instead related to the crystn. of V-oxide particles and is not reversible. It is also shown that Pd-doped V heteropoly acid has a much higher initial activity and selectivity, but the catalyst rapidly deactivates. [on SciFinder(R)]
Titolo: | Deactivation effects in the synthesis of methyl ethyl ketone by selective oxidation over solid Wacker-type catalysts |
Autori: | |
Data di pubblicazione: | 1994 |
Serie: | |
Abstract: | Solid Wacker-type catalysts (Pd-V2O5 or Pd-CeO2 supported on alumina and Pd-doped KH3PV1Mo11O40) show a marked decline in activity in the gas phase selective oxidn. of 1-butene to Me Et ketone, whereas the selectivity passes through a max. After about 5-6 h onstream, nearly steady-state behavior is reached, characterized by a slower deactivation rate and a slight decline in selectivity. The initial change in the catalytic behavior is discussed in terms of the formation of adsorbed species and changes in the valence state of V and Pd during the catalytic reaction. Both these deactivation effects can be reversed by an oxidizing treatment at 300°. The second, slow deactivation is instead related to the crystn. of V-oxide particles and is not reversible. It is also shown that Pd-doped V heteropoly acid has a much higher initial activity and selectivity, but the catalyst rapidly deactivates. [on SciFinder(R)] |
Handle: | http://hdl.handle.net/11570/1907282 |
ISBN: | 978-0-444-81682-5 |
Appare nelle tipologie: | 14.b.1 Contributo in volume (Capitolo o Saggio) |