Catalyst carriers
First Claim
1. A carrier for a catalyst which comprises at least 95% alpha alumina with a surface area of from 1.0 to 2.6 m2/g and a water absorption of from 35 to 55%, wherein the pores are distributed such that at least 80% of the pore volume is in the form of pores having pore diameters from 0.2 to 10 micrometers and pores with diameters less than 0.2 micrometers represent from 0 to 10% of the total pore volume of the carrier.
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Abstract
The selectivity and activity of a silver-based olefin epoxidation catalyst is found to be a function of the pore size distribution in the alumina carrier on which it is deposited. Specifically it is found advantageous to provide a carrier which has a minimum of very large pores, (greater than 10 micrometers) and a water absorption of 35 to 55% and a surface area of at least 1.0 m2/g. A method of making such carriers is also described.
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Citations
16 Claims
- 1. A carrier for a catalyst which comprises at least 95% alpha alumina with a surface area of from 1.0 to 2.6 m2/g and a water absorption of from 35 to 55%, wherein the pores are distributed such that at least 80% of the pore volume is in the form of pores having pore diameters from 0.2 to 10 micrometers and pores with diameters less than 0.2 micrometers represent from 0 to 10% of the total pore volume of the carrier.
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7-11. -11. (canceled)
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12. A catalyst carrier for which comprises at least 95% alpha alumina with a surface area of from 1.0 to 2.6 m2/g and a water absorption of from 35 to 55%, wherein the pores are distributed such that pores having pore diameters from 0.2 to 10 micrometers provide a pore volume of 0.3 to 0.56 mL/g of the carrier.
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13. A catalyst carrier formed by a method comprising:
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forming a mixture comprising;
a) from 50 to 90% by weight of a first particulate alpha alumina having an average particle size (d50) of from 10 to 90 micrometers;
b) from 10 to 50% by weight, based on the total alpha alumina weight, of a second particulate alpha alumina having an average particle size (d50) of from 2 to 6 micrometers;
c) from 2 to 5% by weight of an alumina hydrate;
d) from 0.2 to 0.8% of an amorphous silica compound, measured as silica; and
e) from 0.05 to 0.3% of an alkali metal compound measured as the alkali metal oxide;
all percentages being based on the total alpha alumina content of the mixture;
forming the mixture into particles; and
firing the particles at a temperature of from 1250 to 1470°
C. to form the carrier. - View Dependent Claims (14, 15, 16)
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Specification