Catalyst and process for preparing isoolefins
View Patent ↗The present invention relates to a process for preparing a catalyst which, in a formal sense, comprises 0.1 to 20% by mass of alkali metal and/or alkaline earth metal oxide, 0.1 to 99% by mass of oxide and 0.1 to 99% by mass of silicon dioxide, which is characterized in that it aluminum comprises the steps of treating an aluminosilicate with an aqueous alkali metal and/or alkaline earth metal salt solution under acidic conditions and calcining the aluminosilicate treated with aqueous alkali metal and/or alkaline earth metal salt solution, and to a catalyst which is obtainable by this process and, in a formal sense, comprises alkali metal and/or alkaline earth metal oxide, aluminum oxide and silicon dioxide, which is characterized in that the catalyst, in a formal sense, has a content of alkali metal and/or alkaline earth metal oxides of 0.5 to 20% by mass, a content of aluminum oxide of 4 to 30% by mass and a content of silicon dioxide of 60 to 95% by mass, and to the use of this catalyst in a process for preparing isoolefins having 4 to 6 carbon atoms by catalytic gas phase cleavage of tertiary alcohols or alkyl tert-alkyl ethers.
1. A process for preparing isoolefins having 4 to 6 carbon atoms of the formula I
by catalytic gas phase cleavage of a starting compound of the formula II
to give a compound of the formula I and a compound of the formula III
R—OH III
wherein, in the formulae I to III, the R radical is H or an alkyl radical having 1, 2 or 3 carbon atom(s), the R 1 radical is H or a methyl or ethyl radical, and the R 2 and R 3 radicals are each methyl or ethyl radicals, where the R 2 and R 3 radicals may be the same or different, at a temperature of 110 to 450° C. and a pressure of 0.1 to 2 MPa,
wherein
the catalyst used in the gas phase cleavage comprises:
(i) 0.5 to 20% by mass of a member selected from the group consisting of MgO, or a mixture of an alkaline earth metal oxide and MgO;
(ii) 4 to 30% by mass of aluminum oxide; and
(iii) 60 to 95% by mass of silicon dioxide;
wherein a mean pore diameter of the catalyst is from 5 to 20 nm;
wherein at least 50% of the total pore volume of the catalyst is accounted for by mesopores having a diameter of 3.5 to 50 nm; and
wherein the total pore volume is a sum of the pore volume of the pores having a pore diameter of greater than or equal to 3.5 nm determined by mercury porosimetry according to DIN 66133.
2. The process according to claim 1 , wherein over 70% of the total pore volume of the catalyst is accounted for by mesopores having a diameter of 3.5 to 50 nm.
3. The process according to claim 1 , wherein the compound II cleaved is tert-butanol to isobutene as the compound of the formula I and water as the compound III.
4. The process according to claim 1 , wherein R in said compound of formula II is a methyl, ethyl or propyl radical.
5. The process according to claim 4 , wherein methyl tert-butyl ether is cleaved to isobutene and methanol, or ethyl tert-butyl ether to isobutene and ethanol.
6. The process according to claim 1 , wherein the catalyst comprises 5 to 15% by mass of magnesium oxide, 10 to 20% by mass of aluminum oxide, and 70 to 90% by mass of silicon dioxide.
7. The process according to claim 1 , wherein the catalyst has a BET surface area of 200 to 450 m 2 /g.
8. The process according to claim 1 , wherein the catalyst has a pore volume of 0.5 to 1.3 ml/g.
9. The process according to claim 1 , wherein the mean pore diameter of the catalyst is 8 to 15 nm.
10. The process according to claim 1 , wherein the catalyst has a longest dimension of from 10 μm to 10 mm.
11. A process for preparing isoolefins having 4 to 6 carbon atoms of the formula I
by catalytic gas phase cleavage of a starting compound of the formula II
to give a compound of the formula I and a compound of the formula III
R—OH III
wherein, in the formulae I to III, the R radical is H or an alkyl radical having 1, 2 or 3 carbon atom(s), the R 1 radical is H or a methyl or ethyl radical, and the R 2 and R 3 radicals are each methyl or ethyl radicals, where the R 2 and R 3 radicals may be the same or different, at a temperature of 110 to 450° C. and a pressure of 0.1 to 2 MPa,
wherein
the catalyst used in the gas phase cleavage comprises:
(i) 0.5 to 20% by mass of a member selected from the group consisting of MgO, or a mixture of an alkaline earth metal oxide and MgO;
(ii) 4 to 30% by mass of aluminum oxide; and
(iii) 60 to 95% by mass of silicon dioxide;
wherein a mean pore diameter of the catalyst is from 5 to 20 nm;
wherein at least 50% of the total pore volume of the catalyst is accounted for by mesopores having a diameter of 3.5 to 50 nm;
wherein the total pore volume is a sum of the pore volume of the pores having a pore diameter of greater than or equal to 3.5 nm determined by mercury porosimetry according to DIN 66133; and
wherein said catalyst does not comprise a heavy metal.
12. The process according to claim 11 , wherein the compound II cleaved is tert-butanol to isobutene as the compound of the formula I and water as the compound III.
13. The process according to claim 11 , wherein R in said compound of formula II is a methyl, ethyl or propyl radical.
14. The process according to claim 13 , wherein methyl tert-butyl ether is cleaved to isobutene and methanol, or ethyl tert-butyl ether to isobutene and ethanol.
15. The process according to claim 11 , wherein the catalyst comprises 5 to 15% by mass of magnesium oxide, 10 to 20% by mass of aluminum oxide, and 70 to 90% by mass of silicon dioxide.
16. The process according to claim 11 , wherein the catalyst has a BET surface area of 200 to 450 m 2 /g.
17. The process according to claim 11 , wherein the catalyst has a pore volume of 0.5 to 1.3 ml/g.
18. The process according to claim 11 , wherein the mean pore diameter of the catalyst is 8 to 15 nm.
19. The process according to claim 11 , wherein the catalyst has a longest dimension of from 10 μm to 10 mm.
20. A process for preparing isoolefins having 4 to 6 carbon atoms of the formula I
by catalytic gas phase cleavage of a starting compound of the formula II
to give a compound of the formula I and a compound of the formula III
R—OH III
wherein, in the formulae I to III, the R radical is H or an alkyl radical having 1, 2 or 3 carbon atom(s), the R 1 radical is H or a methyl or ethyl radical, and the R 2 and R 3 radicals are each methyl or ethyl radicals, where the R 2 and R 3 radicals may be the same or different, at a temperature of 110 to 450° C. and a pressure of 0.1 to 2 MPa,
wherein
the catalyst used in the gas phase cleavage comprises:
(i) 0.5 to 20% by mass of a member selected from the group consisting of MgO, or a mixture of an alkaline earth metal oxide and MgO;
(ii) 4 to 30% by mass of aluminum oxide; and
(iii) 60 to 95% by mass of silicon dioxide;
wherein a mean pore diameter of the catalyst is from 5 to 20 nm;
wherein at least 50% of the total pore volume of the catalyst is accounted for by mesopores having a diameter of 3.5 to 50 nm;
wherein the total pore volume is a sum of the pore volume of the pores having a pore diameter of greater than or equal to 3.5 nm determined by mercury porosimetry according to DIN 66133;
wherein said catalyst does not comprise a heavy metal; and
wherein a conversion rate of the compound of formula II is more than 70% and the selectivity of formation of the isoolefin of formula I is over 99%.
21. The process according to claim 20 , wherein the compound II cleaved is tert-butanol to isobutene as the compound of the formula I and water as the compound III.
22. The process according to claim 20 , wherein R in said compound of formula II is a methyl, ethyl or propyl radical.
23. The process according to claim 22 , wherein methyl tert-butyl ether is cleaved to isobutene and methanol, or ethyl tert-butyl ether to isobutene and ethanol.
24. The process according to claim 20 , wherein the catalyst comprises 5 to 15% by mass of magnesium oxide, 10 to 20% by mass of aluminum oxide, and 70 to 90% by mass of silicon dioxide.
25. The process according to claim 20 , wherein the catalyst has a BET surface area of 200 to 450 m 2 /g.
26. The process according to claim 20 , wherein the catalyst has a pore volume of 0.5 to 1.3 ml/g.
27. The process according to claim 20 , wherein the mean pore diameter of the catalyst is 8 to 15 nm.
28. The process according to claim 20 , wherein the catalyst has a longest dimension of from 10 μm to 10 mm.