Hybrid catalysts for the deep catalytic cracking of petroleum naphthas and other hydrocarbon feedstocks
Provided herein are hybrid catalysts that are used in the deep catalytic cracking of petroleum naphthas or other hydrocarbon feedstocks, for the selective production of light olefins, in particular ethylene and propylene and BTX aromatics. The hybrid catalysts of this invention contain a chemically treated microporous crystalline silicate such as the pentasil-type silicalite, a mesoporous silica-alumina or zirconium oxide co-catalyst, into which may be incorporated aluminum oxide, molybdenum oxide, lanthanum oxide, cerium oxide or a mixture of aluminum and molybdenum oxides, and an inorganic binder such as bentonite clay. These novel catalysts show several advantages with respect to the classical steam (thermal) cracking: i) higher combined production of ethylene and propylene; ii) lower ethylene/propylene ratio; iii) much lower production of methane; iv) much lower reaction temperature resulting in significant energy savings; v) easy in-situ regeneration using air as oxidant; vi) lower carbon dioxide and other volatile oxides emitted during the regeneration phase.
1. A hybrid catalyst for use in deep catalytic cracking of hydrocarbon feedstocks to selectively produce light olefins, said hybrid catalyst comprising a microporous catalyst component, a mesoporous catalyst component and a binder, said mesoporous catalyst component comprising a support comprising a substance selected from a large surface area silica-alumina, a zirconium oxide and mixtures thereof, said support having loaded thereon a substance selected from cerium oxide, lanthanum oxide, and mixtures thereof.
2. A hybrid catalyst as defined in claim 1 , wherein said microporous catalyst component is a crystalline pentasil-type silicalite.
3. A hybrid catalyst as defined in claim 2 , wherein said crystalline pentasil-type silicalite is acidic.
4. A hybrid catalyst as defined in claim 2 , wherein said pentasil-type silicalite is desilicated and treated with ammonium ions.
5. A hybrid catalyst as defined in claim 1 , wherein said binder is a bentonite clay.
6. A hybrid catalyst as defined in claim 5 , wherein said bentonite clay is present in a proportion of 9 to 25 wt. % based on the total weight of the hybrid catalyst.
7. A hybrid catalyst as defined in claim 1 , wherein said support further has loaded thereon metal oxides selected from the group consisting of aluminum oxide, molybdenum oxide, and mixtures thereof.
8. A hybrid catalyst as defined in claim 7 , wherein said support has loaded thereon aluminum oxide.
9. A hybrid catalyst as defined in claim 7 , wherein said support has loaded thereon molybdenum oxide.
10. A hybrid catalyst as defined in claim 7 , wherein said support has loaded thereon a mixture of aluminum and molybdenum oxides.
11. A hybrid catalyst as defined in claim 10 , comprising a weight ratio of molybdenum to aluminum oxides of 0.5 to 1.5.
12. A hybrid catalyst as defined in claim 11 , wherein said weight ratio of molybdenum to aluminum oxides is about 1.0.
13. A hybrid catalyst as defined in claim 1 , comprising a weight ratio of microporous to mesoporous catalyst component of 0.25 to 4.0.
14. A hybrid catalyst as defined in claim 13 , wherein said weight ratio of microporous to mesoporous catalyst component is about 1.5.
15. A hybrid catalyst as defined in claim 1 , wherein said zirconium oxide is present in a proportion of 1.5 to 4.0 wt.% based on the total weight of the hybrid catalyst.