Abstract: Process for the production of hydrocarbons from synthesis gas which comprises:a) feeding to a reactor for Fischer-Tropsch reactions, containing a catalyst based on supported cobalt, a synthesis gas in molar ratios H.sub.2 /CO ranging from 1 to 3;b) discharging from the reactor a hydrocarbon liquid phase containing the catalyst, in suspension;c) feeding the suspension to a hydrocracking reactor operating at a temperature ranging from 200 to 500.degree. C.;d) discharging a vapour phase from the head of the hydrocracking reactor and from the bottom a suspension containing heavier products which is recycled to the Fischer-Tropsch reactor;e) cooling and condensing the vapour phase.

Abstract: A catalytic composition for the production of light alpha olefins by ethylene oligomerisation is produced by mixing a zirconium compound with an organic compound selected from the group formed by acetals and ketals, with an aluminium hydrocarbyl compound selected from the group formed by chlorine-containing or bromine-containing aluminium hydrocarbyl compounds and with an aluminium hydrocarbyl compound selected from tris-(hydrocarbyl)-aluminium compounds. Addition of a tris-(hydrocarbyl)-aluminium compound greatly increases the activity. A process for producing light alpha olefins by ethylene oligomerisation is also claimed.

Abstract: A device for the alignment of a laser beam amplification system comprises at least measuring means and alignment templates positioned instead of filtering hole plates of the amplification system, the alignment templates having holes whose centers have substantially the same spatial positions as the centers of the filtering holes, certain template holes being provided with reference sights offset in an angular way with respect to one another, the tips of these sights being pointed towards the center of the holes, the measuring means defining, by sighting at the end of the amplification system, the divergences between the focusing points of the beam in the holes, merged at a single point, and the tips of the sights, their angular positions enabling them to be assigned to their respective holes, the positions of elements of the amplification system being then controlled as a function of the measurements of divergences.

Abstract: The invention concerns an improved process for the conversion of ethylene into butene-1, wherein the ethylene is brought into contact with a catalyst obtained by the reaction of an alkyl titanate, possibly mixed with an ether, with a compound of aluminium of the formula AlR.sub.3 or AlR.sub.2 H, and in the presence of an additive formed by at least one quaternary ammonium salt.

Abstract: The invention concerns an improved process for the conversion of ethylene into light alpha olefins wherein the ethylene is brought into contact with a catalyst obtained by mixing a compound of zirconium with an organic compound selected from the class of acetals and ketals, esters, ketones, ethers, amines, nitrites, anhydrides, chlorides of acids, amides, aldehydes, thioethers, sulphides and disulphides, thiophenes, thioureas and phosphines, and with a chloro or bromo compound of aluminium hydrocarbyl, in the presence of an additive formed by at least one quaternary ammonium salt.