Multiple-stage catalyst system for self-metathesis with controlled isomerization and cracking
Embodiments of processes and multiple-stage catalyst systems for producing propylene comprising introducing a hydrocarbon stream comprising 2-butene to an isomerization catalyst zone to isomerize the 2-butene to 1-butene, passing the 2-butene and 1-butene to a metathesis catalyst zone to cross-metathesize the 2-butene and 1-butene into a metathesis product stream comprising propylene and C 4 -C 6 olefins, and cracking the metathesis product stream in a catalyst cracking zone to produce propylene. The isomerization catalyst zone comprises a silica-alumina catalyst with a ratio by weight of alumina to silica from 1:99 to 20:80. The metathesis catalyst comprises a mesoporous silica catalyst support impregnated with metal oxide. The catalyst cracking zone comprises a mordenite framework inverted (MFI) structured silica catalyst.
1. A process for production of a propylene from a hydrocarbon stream comprising 2-butene using three catalysts in a three-stage catalyst system that include an isomerization catalyst zone, a metathesis catalyst zone downstream of the isomerization zone, and a catalyst cracking zone downstream of the metathesis catalyst zone, the process comprising:
introducing the hydrocarbon stream comprising 2-butene to the isomerization catalyst zone to isomerize the 2-butene to 1-butene, where the isomerization catalyst zone comprises a silica-alumina catalyst with a ratio by weight of alumina to silica from 1:99 to 20:80 and a surface area of 225 m 2 /g to 350 m 2 /g;
passing the 2-butene and 1-butene to the metathesis catalyst zone to cross-metathesize the 2-butene and 1-butene into a metathesis product stream comprising the propylene and C 4 -C 6 olefins, where the metathesis catalyst zone comprises a mesoporous silica catalyst support impregnated with a metal oxide to form a mesoporous silica catalyst; and
cracking the metathesis product stream in the catalyst cracking zone to produce the propylene, where the catalyst cracking zone comprises a mordenite framework inverted (MFI) structured silica catalyst,
wherein the MFI structured silica catalyst is directly downstream of the mesoporous silica catalyst such that the metathesis product stream is passed directly from the mesoporous silica catalyst to the MFI structured silica catalyst.
2. The process of claim 1 where the silica-alumina catalyst has a pore volume of at least 0.60 cm 3 /g.
3. The process of claim 1 where the silica-alumina catalyst comprises an alumina to silica weight ratio between 1:99 and 10:90.
4. The process of claim 1 where the metal oxide of the mesoporous silica catalyst comprises one or more oxides of molybdenum, rhenium, tungsten, or combinations thereof.
5. The process of claim 1 where the metal oxide of the mesoporous silica catalyst is tungsten oxide (WO 3 ).
6. The process of claim 1 where the mesoporous silica catalyst has a pore volume of at least 0.60 cm 3 /g.
7. The process of claim 1 where the MFI structured silica catalyst includes a total acidity of 0.001 mmol/g to 0.3 mmol/g.
8. The process of claim 1 where the hydrocarbon stream is a Raffinate 2 stream from a fluid catalytic cracker or an ethylene cracker.