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 multiple-stage catalyst system for producing propylene from a hydrocarbon stream comprising 2-butene, the multiple-stage catalyst system comprising an isomerization catalyst zone, a metathesis catalyst zone downstream of the isomerization zone, and a cracking catalyst zone downstream of the metathesis catalyst zone 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, where the silica-alumina catalyst zone isomerizes the 2-butene to 1-butene;
the metathesis catalyst zone comprises a mesoporous silica catalyst support impregnated with metal oxide to form a mesoporous silica catalyst, where the mesoporous silica catalyst zone cross-metathesizes the 2-butene and 1-butene into a metathesis product stream comprising propylene and C 4 -C 6 olefins;
the cracking catalyst zone comprises a mordenite framework inverted (MFI) structured silica catalyst, where the cracking catalyst zone cracks the metathesis product stream to produce propylene; and
the MFI structured 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 multiple-stage catalyst system of claim 1 where the isomerization catalyst zone, the metathesis catalyst zone, and the cracking catalyst zone are disposed in one reactor.
3. The multiple-stage catalyst system of claim 1 where the isomerization catalyst zone is disposed in a first reactor, the metathesis catalyst zone is disposed in a second reactor downstream of the first reactor, the cracking catalyst zone is disposed in a third reactor downstream of the second reactor, and a direct conduit extends between the second reactor and the third reactor.
4. The multiple-stage catalyst system of claim 1 where the isomerization catalyst zone is disposed in a first reactor, the cracking catalyst zone is disposed in a second reactor downstream of the first reactor, and the metathesis catalyst zone is disposed in the first reactor downstream of the isomerization catalyst zone with a direct conduit extending between the first reactor and the second reactor or in the second reactor directly upstream of the cracking catalyst zone.
5. The multiple-stage catalyst system of claim 1 where the silica-alumina catalyst includes a surface area of 200 m 2 /g to 600 m 2 /g.
6. The multiple-stage catalyst system of claim 1 where the silica-alumina catalyst has a pore volume of at least 0.60 cm 2 /g.
7. The multiple-stage catalyst system of claim 1 where the silica-alumina catalyst comprises an alumina to silica weight ratio between 1:99 and 10:90.
8. The multiple-stage catalyst system of claim 1 where the metal oxide of the mesoporous silica catalyst comprises one or more oxides of molybdenum, rhenium, tungsten, or combinations thereof.
9. The multiple-stage catalyst system of claim 1 where the metal oxide of the mesoporous silica catalyst is tungsten oxide (WO 3 ).
10. The multiple-stage catalyst system of claim 1 where the mesoporous silica catalyst has a pore volume of at least 0.60 cm 3 /g.
11. The multiple-stage catalyst system of claim 1 where the MFI structured silica catalyst includes a total acidity of 0.001 mmol/g to 0.3 mmol/g.