Abstract: Catalytic solids based on titanium trichloride complex, usable for the stereospecific polymerization of alpha-olefins, obtained by heat treatment, in the presence of a halogenated activating agent, of the liquid material resulting from bringing TiCl.sub.4, pretreated with an electron-donor compound, into contact with a composition (C) corresponding to the general formulaAlR.sub.p (Y) .sub.q X .sub.3-(p+q)in whichR represents a hydrocarbon radical or a hydrogen atom;Y represents a group chosen from --OR', --SR' and --NR'R", in which R' and R" each represent a hydrocarbon radical or a hydrogen atom;X represents a halogen;p is an arbitrary number such that 0<p<3; andq is an arbitrary number such that 0<q<3; the sum (p+q) being such that 0<(p+q).ltoreq.3.These catalytic solids of controllable porosity permit the production of a wide range of propylene polymers, in particular the propylene and ethylene copolymers known as "block" copolymers.

Abstract: The invention relates to catalytic compositions for the hydrogenation of chlorofluoroalkenes to fluoroalkenes, comprising a porous carrier impregnated with metal of group VIII of the Periodic Table of the elements and with one or more compounds chosen from the salts of an alkali metal or alkaline-earth metal.The invention also relates to a process for obtaining these catalytic compositions and a process of hydrogenation by means of these catalytic compositions.