EP0067459A1 — Silica particles and method for their preparation

Claim 1

Independent Claim 106 words

Process for the preparation of silica particles which comprises a) preparing a silica hydrosol by mixing an aqueous solution of an alkalimetal silicate with an a q uous solution of an acid. b) converting the hydrosol into droplet form. c) shaping the droplets in air or in a liquid which is not miscible with water. d) partially pre-drying the hydrogel particles obtained. e) subjecting the partially pre-dried oarticles to a hydrothermal treatment. f) decreasing the cation content of the hydrogel particles thus treated in an aaueous medium to less than 10%w. calculated on dry material. and g) drying and optionally calcining the silica particles thus obtained.

Claim 2

Dependent Claim 106 words

Process for the preparation of silica particles which comprises a) preparing a silica hydrosol by mixing an aqueous solution of an alkalimetal silicate with an a q uous solution of an acid. b) converting the hydrosol into droplet form. c) shaping the droplets in air or in a liquid which is not miscible with water. d) partially pre-drying the hydrogel particles obtained. e) subjecting the partially pre-dried oarticles to a hydrothermal treatment. f) decreasing the cation content of the hydrogel particles thus treated in an aaueous medium to less than 10%w. calculated on dry material. and g) drying and optionally calcining the silica particles thus obtained.

Claim 3

Dependent Claim 33 words

Process according to claim 1. wherein the amount of water to be removed from the hydrogel particles is between 45%w and 85%w, calculated on the amount of water initially present in the hydrogel.

Claim 4

Dependent Claim 38 words

Process according to claim or 2 wherein the amount of water to be remaining in the predried particles is between 12%w and 70%w, preferably between and 50%w. calculated on the amount of water initially present in the hydrogel.

Claim 5

Dependent Claim 27 words

Process according to anv one of claims 1 - 3 wherein the partial predrying is achieved at a temperature in the range of from 70°C to 180°C.

Claim 6

Dependent Claim 32 words

Process according to any one of claims 1 - 4 wherein the hydrothermal treatment is carried out at a temperature between 80°C and 350°C, preferably at a temperature between 100°C and 300°C.

Claim 7

Dependent Claim 33 words

Process according to claim 5 wherein the hydrothermal treatment is carried out using a quantity of liquid water at least substantially equal in volume to that of the silica particles to be treated.

Claim 8

Dependent Claim 30 words

Process according to any one of claims 1 - 6 wherein the amount of cation is reduced below 7%w, calculated on dry material, preferably below 1%w, calculated on dry material.

Claim 9

Dependent Claim 37 words

Process according to any one of claims 1-7 wherein the dried hydrogel is subjected to a calcination at a temperature up to 1000 o C, preferably at a temperature in the range of from 800°C to 950°C.

Claim 10

Dependent Claim 168 words

Silica particles having a pore size distribution wherein at least 70% of the pore volume is made up of pores having pore diameters which have a tolerance of not more than 10 nm on the mean pore diameter and at least 60% of the pore volume is made up of pores having pore diameters which have a tolerance of not more than 5 nm on the mean pore diameter when the mean pore diameter is not more than 30 nm (as determined by mercury porosimetry) and having a pore size distribution wherein at least 65% of the pore volume is made up of pores having pore diameters which have a tolerance of not more than 20 nm on the mean pore diameter and at least 55% of the pore volume is made up of pores having pore diameters which have a tolerance of not more than 10 nm on the mean pore diameter when the mean pore diameter is more than 30 nm (as determined by mercury porosimetry).

Claim 11

Dependent Claim 168 words

Silica particles having a pore size distribution wherein at least 70% of the pore volume is made up of pores having pore diameters which have a tolerance of not more than 10 nm on the mean pore diameter and at least 60% of the pore volume is made up of pores having pore diameters which have a tolerance of not more than 5 nm on the mean pore diameter when the mean pore diameter is not more than 30 nm (as determined by mercury porosimetry) and having a pore size distribution wherein at least 65% of the pore volume is made up of pores having pore diameters which have a tolerance of not more than 20 nm on the mean pore diameter and at least 55% of the pore volume is made up of pores having pore diameters which have a tolerance of not more than 10 nm on the mean pore diameter when the mean pore diameter is more than 30 nm (as determined by mercury porosimetry).

Claim 12

Dependent Claim 156 words

Silica particles according to claim 9, having a pore size distribution wherein at least 75% of the pore volume is made up of pores having pore diameters which have a tolerance of not more than 10 nm on the mean pore diameter and at least 65% of the pore volume is made up of pores having pore diameters which have a tolerance of not more than 5 nm on the mean pore diameter when the mean pore diameter is not more than 30 nm and at least 75% of the pore volume is made up of pores having pore diameters which have a tolerance of not more than 20 nm on the mean pore diameter and at least 65% of the pore volume is made up of pores having pore diameters which have a tolerance of not more than 10 nm on the mean pore diameter when the mean pore diameter is more than 30 nm.

Claim 13

Dependent Claim 29 words

Silica particles, especially silica spheres, according to claim 9 or 10 having a loss on attrition of less than 0.1%w as determined by the standard attrition test described hereinbefore.

Claim 14

Dependent Claim 39 words

Catalysts comprising one or more metals or metal compounds with catalytic activity on silica particles according to any one of claims 9-11 as carrier, or on silica particles, prepared by a process according to any one of claims 1-8.

Claim 15

Dependent Claim 67 words

Process for the hydrodemetallization of a heavy hydrocarbon oil wherein the heavy oil is contacted at elevated temperature and pressure and in the presence of hydrogen with a catalyst according to claim 12, which catalyst comprises at least one metal selected from the group consisting of nickel and cobalt and at least one metal selected from the group of molybdenum, tungsten and vanadium as catalytically active metals.

Claim 16

Dependent Claim 50 words

Process for the epoxidation of olefinically unsaturated compounds with an organic hydroperoxide wherein the reactants are contacted with a catalyst according to claim 12, which catalyst comprises at least one metal or metal compound selected from the group consisting of molybdenum, tungsten, titanium, zirconium and vanadium as catalytically active compounds.

Claim 17

Dependent Claim 20 words

Process for the purification of exhaust gases wherein the exhaust gases are contacted with a catalyst according to claim 12.

Claim 18

Dependent Claim 25 words

Process for the hydration of olefinically unsaturated compounds wherein the reactants are contacted with a catalyst according to claim 12, which catalyst comprises phosphoric acid.

Silica particles and method for their preparation

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