Abstract: Process for preparing zeolites of X type having an Si/Al atomic ratio of ≦1.5 and having exchangeable cations including lithium, trivalent and/or divalent ions, and optionally sodium, potassium, ammonium and/or hydronium ions, involves distributing starting zeolite in a series of receptacles, percolating a solution of at least one lithium compound through the series, drawing a lithium-containing bleed from first receptacle of the carrousel, and drawing off a final effluent stream from a final receptacle in the series. The effluent stream contains compounds of exchangeable cations from the starting zeolite and traces of the lithium compound(s). After a desired degree of lithium exchange has occurred in the first receptacle, the first receptacle is removed and a fresh solution of at least one lithium compound is introduced into the next receptable in the series and percolated through the series. This step can be performed for each receptacle in the series.

Abstract: The present invention relates to a process for the preparation of zeolites X and LSX agglomerated with a binder and for which approximately 50 to approximately 99% of the exchangeable sites are occupied by lithium ions, which consists in carrying out the exchange with lithium of a portion of the exchangeable cations of the starting zeolite by bringing the said zeolite, distributed in a carrousel of at least 2 receptacles in the stationary bed form which are arranged in series in an interchangeable manner, into contact with a solution of lithium compounds (1) conveyed through the-said carrousel whose sequence of receptacles is modified cyclically at given time intervals; when the desired degree of exchange with regard to lithium is achieved for the zeolite of the 1st receptacle, the latter is taken out of the carrousel and the zeolite which is present therein is freed from the solution of lithium compounds by washing, then discharged (4) and optionally replaced by a fresh charge of zeolite to be exchanged, and

Abstract: A process for the manufacture of a polymer having at least one property P with a desired value D, the process being controlled by periodically sampling the polymer produced, or being produced by the process, determining the value of the property P by applying a correlation relationship with n results R.sub.i of n absorbance measurements obtained by analyzing the sample with an infrared spectrometer at n wavelengths in the near infrared region and then using the difference between the determined value of the property P and the desired value D to control the process parameters using a process computer.

Abstract: Process for the preparation of copolymers of ethylene and an alpha-olefin having six carbon atoms comprising hexene-1 or 4-methyl-pentene-1 with a density comprised between 0.910 and 0.940, involving a copolymerization of ethylene and an alpha-olefin having six carbon atoms comprising hexene-1 or 4-methyl-pentene-1 in the gas phase by means of a fluidized bed, in the presence of a catalyst system comprising on the one hand a co-catalyst consisting of at least one organo-metallic compound of a metal of Groups, II and III of the Periodic Table of Elements and on the other hand a supported catalyst comprising a special support based essentially on magnesium chloride and optionally aluminum chloride, on which support there has been precipitated a derivative of a transition metal of Groups IV, V and VI of the Periodic Table of Elements.