Process for the isomerization of olefins
A process is useful for the isomerization of C 4 to C 9 olefins having an internal double bond into the corresponding olefins having a terminal double bond using a heterogeneous catalyst system of a silicon-aluminium mixed oxide composition.
1. A process for the isomerization of C 4 to C 9 reactant olefins having an internal double bond to product olefins having a terminal double bond using a heterogeneous catalyst, the process comprising:
isomerizing said reactant C 4 to C 9 olefins using the heterogeneous catalyst at a temperature between 200° C. and 450° C., wherein the catalyst comprises a silicon-aluminium mixed oxide composition, having the following composition:
a) 96% to 99.99% by weight of silicon oxide, calculated as SiO 2 ; and
b) 0.01% to 4% by weight of aluminium oxide, calculated as Al 2 O 3 .
2. The process according to claim 1 , wherein the catalyst has the following composition:
a) 98.5% to 99.95% by weight of silicon oxide, calculated as SiO 2 ; and
b) 0.05% to 1.5% by weight of aluminium oxide, calculated as Al 2 O 3 .
3. The process according to claim 1 , wherein the silicon-aluminium mixed oxide composition has a BET surface area of 50 to 250 m 2 /g.
4. The process according to claim 1 , wherein the catalyst consists of shaped bodies produced from the silicon-aluminium mixed oxide composition in a forming process with the addition of binders and at least temporary auxiliaries.
5. The process according to claim 1 , wherein the isomerization is carried out using a hydrocarbon mixture that comprises the reactant olefin to be isomerized and the product olefin, wherein the content of the product olefin is increased through isomerization.
6. The process according to claim 1 , wherein the isomerization is carried out at a gas hourly space velocity from 2000 to 8000 h −1 .
7. The process according to claim 1 , wherein the reactant olefins used are C 4 to C 8 reactant olefins having an internal double bond.
8. The process according to claim 1 , wherein the reactant olefins used are cis-2-butenes, trans-2-butenes, or a hydrocarbon mixture comprising these 2-butenes; and wherein the product olefin having a terminal double bond is 1-butene.
9. The process according to claim 1 , wherein the silicon-aluminium mixed oxide composition is predominantly or entirely present in the form of aggregated primary particles.
10. The process according to claim 9 , wherein the silicon-aluminium mixed oxide composition, wherein a weight ratio (Al 2 O 3 /SiO 2 ) surface of the primary particles in a near-surface region is smaller than a weight ratio (Al 2 O 3 /SiO 2 ) total in the totality of the primary particles.
11. The process according to claim 9 , wherein the silicon-aluminium mixed oxide composition is predominantly or entirely present in the form of aggregated primary particles in which:
I) a weight ratio of (Al 2 O 3 /SiO 2 ) total in the totality of the primary particles is 0.002 to 0.05, and
II) a weight ratio (Al 2 O 3 /SiO 2 ) surface of the primary particles in a near-surface layer having a thickness of 5 nm is less than the weight ratio in the totality of the primary particles.
12. The process according to claim 1 , wherein the catalyst is completely crystalline, partly crystalline or X-ray amorphous.
13. The process according to claim 12 , wherein the catalyst is X-ray amorphous.
14. The process according to claim 1 , wherein the silicon-aluminium mixed oxide composition has a BET surface area of 100 to 220 m 2 /g.
15. The process according to claim 1 , wherein the isomerization is carried out at a gas hourly space velocity from 2500 to 4000 h −1 .
16. The process according to claim 1 , wherein the reactant olefins used are C 4 reactant olefins having an internal double bond.
17. The process according to claim 11 , wherein the weight ratio of (Al 2 O 3 /SiO 2 ) total in the totality of the primary particles is 0.005 to 0.01.