Abstract: The composition is based on zirconium oxide and at least one additive selected from zirconium oxide and at least one additive chosen from praseodymium, lanthanum or neodymium oxides, has a specific surface of at least 29 m 2/g after calcination at 1000° C. during a period of 10 hours and is obtained by a method wherein a mixture of zirconium compounds and additive is precipitated with a base; the medium thus obtained, containing a precipitate, is heated and a compound chosen from anionic surfactants, non-ionic surfactants, polyethylene glycols, carboxylic acids and the salts thereof and surfactants such as the ethoxylates of caroboxymethyl fatty alcohols is added to the compound and the precipitate is calcinated; the composition can be used as a catalyst.

Abstract: The composition is based on zirconium oxide and at least one additive selected from zirconium oxide and at least one additive chosen from praseodymium, lanthanum or neodymium oxides, has a specific surface of at least 29 m 2/g after calcination at 1000° C. during a period of 10 hours and is obtained by a method wherein a mixture of zirconium compounds and additive is precipitated with a base; the medium thus obtained, containing a precipitate, is heated and a compound chosen from anionic surfactants, non-ionic surfactants, polyethylene glycols, carboxylic acids and the salts thereof and surfactants such as the ethoxylates of caroboxymethyl fatty alcohols is added to the compound and the precipitate is calcinated; the composition can be used as a catalyst.

Abstract: The composition is based on zirconium oxide and at least one additive selected from zirconium oxide and at least one additive chosen from praseodymium, lanthanum or neodymium oxides, has a specific surface of at least 29 m 2/g after calcination at 1000° C. during a period of 10 hoursand is is obtained by a method wherein a mixture of zirconium compounds and additive is precipitated with a base; the medium thus obtained, containing a precipitate, is heated and a compound chosen from anionic surfactants, non-ionic surfactants, polyethylene glycols, carboxylic acids and the salts thereof and surfactants such as the ethoxylates of caroboxymethyl fatty alcohols is added to the compound and the precipitate is calcinated; the composition can be used as a catalyst.

Abstract: Finely divided and free-flowing powders of a thermotropic polymer, e.g., a wholly aromatic polyester or a wholly aromatic polyesteramide, are produced by (a) extruding a melt of such thermotropic polymer through an extrusion apparatus including a downstream die member to provide at least one solid cylindrical profile thereof, during which extrusion (i) the molten thermotropic polymer is at a temperature T.sub.1 greater than the melting temperature T.sub.M thereof at which the liquid crystal phase develops, while (ii) cooling such molten thermotropic polymer no later than the instant of its inlet entry into the die member to a temperature T.sub.2 ranging from a value 7.degree. C. less than the temperature T.sub.M to a minimum value equal to the crystallization temperature T.sub.c thereof, and (iii) maintaining this temperature T.sub.