Bifunctional catalyst comprising phosphorous
A bifunctional catalyst for example for conversion of oxygenates, the bifunctional catalyst comprising zeolite, alumina binder, Zn and P, wherein Zn is present at least partly as ZnAl 2 O 4 .
1. A bifunctional catalyst comprising a ZSM-5 or ZSM-11 zeolite, an alumina binder, Zn and P, wherein the Zn and P is present throughout the catalyst in both the binder and the zeolite, the catalyst has a total Zn content of more than 7 wt %, at least 95% of the Zn in the binder is present as ZnAl 2 O 4 and the molar amount of Zn present in the binder phase as ZnO is less than 5% relative to the total amount of Zn present in the binder, the molar ratio of Zn/P is greater than 1, the alumina binder is a pure alumina binder or an alumina-based binder comprising mixtures of aluminum oxide and aluminum hydroxide and/or silica alumina, and wherein the Zn in the alumina binder is fully or partly spinelized.
2. A bifunctional catalyst according to claim 1 , wherein the catalyst is an extruded or pelletized catalyst.
3. A bifunctional catalyst according to claim 1 , comprising 30-65 wt % zeolite, 1-40 wt % ZnAl 2 O 4 , up to 40 wt % Al 2 O 3 , and up to 10 wt % ZnO.
4. A bifunctional catalyst according to claim 1 , wherein the alumina binder further comprises silica.
5. A bifunctional catalyst according to claim 1 , wherein the catalyst, by X-ray diffraction, does not contain free ZnO in the binder.
6. A bifunctional catalyst according to claim 1 , wherein the total Zn content is 7-25 wt % in the catalyst.
7. A bifunctional catalyst according to claim 1 , wherein the molar amount of Zn present in the binder as ZnAl 2 O 4 constitutes at least 99% of the total amount of Zn present in the binder.
8. A bifunctional catalyst according to claim 1 , wherein the Zn in the zeolite is present as ZnO, Zn(OH)+ and/or Zn++ in ion exchange positions.
9. A bifunctional catalyst according to claim 1 , wherein the total Zn content in the catalyst is 8-15 wt % Zn.
10. A bifunctional catalyst according to claim 1 , wherein the Zn content in the binder is substantially the same regardless of whether the catalyst is in a fully or partly spinelized form.
11. A bifunctional catalyst according to claim 10 , wherein the fully spinelized form is obtained by heating a partly spinelized form at 300-550° C. in an atmosphere comprising steam.