Process for manufacturing a carrier of titanium dioxide

A process for the manufacture of a carrier for an active entity which comprises selecting by sieving from raw granular anatase titanium dioxide having an average particle size of less than 840 microns the fraction having a particle size within the range of 150 microns to 350 microns, and heating the selected fraction at a temperature of from 1050.degree. C. to 1300.degree. C. for a time sufficient to produce a product having a hardness of at least 65, a bulk density of greater than 1.0 grams per milliliter, a specific surface area of less than 3 square meters per gram and with at least 50% by weight of the titanium dioxide in the rutile form.

A process for the manufacture of a carrier for an active entity which comprises selecting by sieving from raw granular anatase titanium dioxide having an average particle size of less than 840 microns the fraction having a particle size within the range of 150 microns to 350 microns, pelletizing the selected fraction and heating the pelletized product at a temperature of from 1050.degree. C. to 1300.degree. C. for a time sufficient to produce a product having a hardness of from 85 to 100, a bulk density of from 1.2 to 1.8 grams per milliliter, a specific surface area of from 0.6 to 2 square meters per gram and with at least 50% by weight of the titanium dioxide in the rutile form.

A process for the manufacture of a carrier for an active entity comprising precipitating TiO.sub.2 by mixing together in aqueous medium titanium tetrachloride and an alkali, the amounts of alkali and titanium tetrachloride being such that upon completion of the mixing, the mixture has a pH greater than 7, separating the precipitated titanium dioxide, drying the separated titanium dioxide and heating the dried titanium dioxide at a temperature of from 850.degree. C. to 1300.degree. C. for a time sufficient to produce a product having a hardness of from 85 to 100, a bulk density of greater than 1.0 grams per milliliter, a specific surface area of from 0.6 to 2 square meters per gram and with at least 90% by weight of the titanium dioxide in the rutile form.

A process for the manufacture of a carrier for an active entity which comprises selecting by sieving from raw anatase titanium dioxide the fraction having a particle size within the range 150 microns to 350 microns and heating the selected fraction at a temperature and for a time sufficient to produce a product having a hardness of at least 40, a bulk density of at least 0.8 grams per milliliter, a specific surface area of less than 5 square meters per gram and with at least 90% by weight of the titanium dioxide in the rutile form.