Silica-containing shaped articles and a process for their preparation
AssigneeBayer Aktiengesellschaft
InventorsAdolf Wissner, Josef Haydn, Udo Birkenstock
Life of this patent
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Abstract
In the new shaped articles a hollow space or a lumpy inorganic base material is surrounded by a porous silica-containing layer. They can be prepared by applying silica sol or a mixture containing water, silica sol and/or waterglass and, if appropriate, finely pulverulent water-insoluble silica and/or porosity producing agents to a lumpy base material, and, if use is made of organic base materials, then removing these organic base materials by heating. The new shaped articles can be used as support material for catalysts or, if the layer containing the porous silica contains catalytically active substances, as catalysts.
Claims26
A process for preparing silica-containing shaped articles, comprising applying a mass selected from the group consisting of silica sol, a mixture containing water, silica sol and waterglass and a mixture containing water and waterglass to a base material while the temperature of the base material is, at the start of the application of the silica sol or of the mixture, below the softening point of the base material and, as the application of the silica sol or of the mixture proceeds, above the boiling temperature of water, and the silica sol or the mixture is added in such a way that the water evaporates rapidly and the water content of the base material is always less than 5% by weight, whereby to surround the base material with a porous silica-containing layer.
A silica-containing shaped article comprising a base material surrounded by a firmly adhering layer consisting essentially of porous silica and a catalytically active substance or precursor thereof, said base layer having an absorbency less than 10 g of water per 100 g, a BET surface area below 5 m.sup.2 /g and a thickness of 10 to 3,000 .mu.m.
A silica-containing shaped article produced by a process comprising applying a mass selected from the group consisting of silica sol, a mixture containing water, silica sol and waterglass, a mixture containing water and waterglass and a mixture containing water and silica sol, said silica sol containing finely pulverulent water-insoluble silica having a primary particle size in a range of 1 to 200 nm and an agglomerate size withing a range of 0.5 to 100 .mu.m, to a base material having an absorbency of less than 10 g of water per 100 g and a BET surface area of less than 5 m.sup.2 /g, while the temperature of the base material is, at the start of the application of the silica sol or the mixtures, below the softening point of the base material and, as the application of the silica sol or of the mixtures proceed, above the boiling temperature of water, and adding the silica sol or the mixtures in such a way that the water evaporates rapidly and the water content of the base material is always less than 5% by weight.
Dependencies are inferred from the claim text.