Abstract: This invention relates to a solid divided composition comprising grains whose mean size is greater than 25 ?m and less than 2.5 mm, wherein each grain is provided with a solid porous core and a homogeneous continuous metal layer consisting of at least one type of transition non-oxidised metal and extending along a gangue coating the core in such a way that pores are inaccessible. A method for the production of said composition and for the use thereof in the form of a solid catalyst is also disclosed.

Abstract: This invention relates to a solid divided composition comprising grains whose mean size is greater than 25 ?m and less than 2.5 mm, wherein each grain is provided with a solid porous core and a homogeneous continuous metal layer consisting of at least one type of transition non-oxidised metal and extending along a gangue coating the core in such a way that pores are inaccessible. A method for the production of said composition and for the use thereof in the form of a solid catalyst is also disclosed.

Abstract: The invention relates to a method for selectively producing nanotubes made of carbon ordered by decomposing a gaseous carbon source in contact with at least one solid catalyst in the form of catalyst grains which are made of an alumina porous support provided with a metallic ferrous non-oxidised deposit and whose mean grain-size ranges from 25 ?m to 2.5 mm and on which said metallic ferrous deposit covers more than 75% of the surface of the microscopic alumina support and is embodied in the form of at least one cluster formed by a plurality of metallic agglutinated bulbs.