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US 2015/0030518 A1Published application
Process for preparing precipitated silica having specific morphology, particle size and porosity
AssigneeRhodia Operations
InventorsEmmanuelle Allain, Sylvaine Neveu
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Abstract
The invention relates to a process for the preparation of precipitated silica formed of aggregates of large primary silica particles, at the surface of which occur small primary silica particles, in which the acid used in at least one of the process steps is a concentrated acid.
Claims15
A process for preparing precipitated silica comprising a reaction of a silicate with at least one acid, whereby a silica suspension is obtained, and then separation and drying of said silica suspension, wherein the reaction of the silicate with the at least one acid is carried out in the following steps:
- (i) preparing an aqueous precipitated silica suspension, exhibiting a pH of between 2.5 and 5.3, and
- (ii) bringing said aqueous precipitated silica suspension into contact with an acid and a silicate to form a reaction medium, so that the pH of the reaction medium is maintained between 2.5 and 5.3,
- wherein in said process:
- a concentrated acid is used in said step (i) and/or
- the acid added in said step (ii) is a concentrated acid,
- said concentrated acid being selected from the group consisting of sulfuric acid with a concentration of at least 80% by weight, acetic acid with a concentration of at least 90% by weight, formic acid with a concentration of at least 90% by weight, nitric acid with a concentration of at least 60% by weight, phosphoric acid with a concentration of at least 75% by weight and hydrochloric acid with a concentration of at least 30% by weight.
3 more elements
Dependencies are inferred from the claim text.