Modified Y-zeolite/ZSM-5 catalyst for increased propylene production
Provided is a Fluid Catalytic Cracking catalyst composition having increased propylene production with respect to other Fluid Catalytic Cracking catalysts (measured at constant conversion). The catalyst composition comprises a particulate which comprises (a) non-rare earth metal exchanged Y-zeolite in an amount in the range of about 5 to about 50 wt %, based upon the weight of the particulate; and (b) ZSM-5 zeolite in an amount in the range of about 2 to about 50 wt %, based upon the weight of the particulate.
1. An FCC catalyst composition comprising a mixture of at least two particulates,
at least one first particulate comprising a Y-zeolite exchanged with a non-rare earth metal, wherein the Y-zeolite exchanged with a non-rare earth metal is in an amount in the range of about 15 to about 40 wt %, based upon the combined weight of the particulates, and
at least one second particulate comprising a zeolite in a matrix, wherein the zeolite consists of a ZSM-5 zeolite, wherein the ZSM-5 zeolite is in an amount in the range of about 2 to about 15 wt %, based upon the combined weight of the first particulates comprising the Y-zeolite exchanged with a non-rare earth metal and the second particulates comprising a zeolite in a matrix, the zeolite consisting of ZSM-5,
wherein the Y-zeolite exchanged with a non-rare earth metal and the ZSM zeolite are in a weight ratio in the range of about 1.2 to about 20 Y-zeolite to ZSM zeolite, and
wherein the non-rare earth metal is magnesium, calcium or strontium.
2. An FCC catalyst composition as in claim 1 wherein said non-rare earth metal comprises magnesium.
3. An FCC catalyst composition as in claim 2 wherein said FCC catalyst composition is prepared by a process comprising magnesium/hydrogen ion exchange with an unexchanged Y-zeolite.
4. An FCC catalyst composition as in claim 2 wherein the magnesium is in an amount measured as magnesium oxide in the range of about 0.25 to about 3.0 wt % percent.
5. An FCC catalyst composition as in claim 1 wherein the FCC catalyst composition comprises a total non-rare earth metal content in the range of about 0.2 to about 3 wt % percent.
6. An FCC catalyst composition as in claim 1 wherein the Y zeolite is an ultrastabilized faujasite Y zeolite.
7. A process for producing propylene from a hydrocarbon feedstock, said process comprising the steps of:
a) providing an FCC catalyst composition comprising a mixture of at least two particulates,
at least one first particulate comprising a Y-zeolite exchanged with a non-rare earth metal, wherein the Y-zeolite exchanged with a non-rare earth metal is in an amount in the range of about 15 to about 40 wt %, based upon the combined weight of the particulates, wherein the non-rare earth metal is magnesium, calcium or strontium, and
at least one second particulate comprising a zeolite in a matrix, wherein the zeolite consists of a ZSM-5 zeolite, wherein the ZSM-5 zeolite is in an amount in the range of about 2 to about 15 wt %, based upon the combined weight of the first particulates comprising the Y-zeolite exchanged with a non-rare earth metal and the second particulates comprising a zeolite in a matrix, the zeolite consisting of ZSM-5,
wherein the Y-zeolite exchanged with a non-rare earth metal and the ZSM zeolite are in a weight ratio in the range of about 1.2 to about 20 Y-zeolite to ZSM zeolite; and
b) contacting the FCC particulate catalyst composition with the hydrocarbon feedstock, at one or more temperatures in the range of about 400 to about 650° C., with a dwell time in the range of about 0.5 to about 12 seconds.
8. A process as in claim 7 wherein contacting in b) takes place in a fluidized bed reactor.
9. A process as in claim 7 wherein the non-rare earth metal comprises magnesium.
10. A process as in claim 9 wherein the FCC catalyst composition comprises an amount of a magnesium salt measured as magnesium oxide in the range of from 0.25 to 3.0 wt %.
11. A process as in claim 7 wherein the resulting yield of propylene is greater, as compared with the resulting yield of propylene of the same process but modified to use an unexchanged Y-zeolite instead of said non-rare earth metal exchanged Y-zeolite on a weight-for-weight basis, the comparison being made at a feedstock conversion in the range of about 40 to about 90 weight percent conversion.
12. A process as in claim 7 wherein the FCC catalyst composition further comprises an amount of alumina in the range of 0 to about 35 wt %, an amount of silica sol in the range of 0 to about 25 wt %, and the remaining balance being clay.
13. A process as in claim 7 wherein:
the Y zeolite is an ultrastabilized faujasite Y zeolite; and/or
propylene is formed with a conversion efficiency in the range of about 4 to about 20 wt %, based upon the weight of the hydrocarbon feedstock.
14. A process as in claim 7 wherein the ZSM-5 is about 40 wt % of the second particulate.
15. An FCC catalyst composition as in claim 1 wherein the ZSM-5 is about 40 wt % of the second particulate.