Abstract: The invention relates to an alumino-silicate type catalyst containing an omega zeolite with a Si/Al atomic ratio of between 2.5 and 100, with a content by weight of sodium of less than 2000 ppm (in relation to the weight of dry zeolite) and further containing, at least one metal selected from group IIa, IIb, and IVa metals, and at least one group VIII metal.The catalyst is prepared by the grafting of an organometallic compound of said group IIa, IVb, IIb, IVa metals.The catalyst is particularly suitable for the isomerization of an aromatic C.sub.8 cut.

Abstract: The invention relates to an alumino-silicate type catalyst containing an omega zeolite with a Si/Al atomic ratio of between 2.5 and 100, with a content by weight of sodium of less than 2 000 ppm (in relation to the weight off dry zeolite) and further containing, at least one metal selected from group IIa, IIb, and IVa metals, and at least one group VIII metal.The catalyst is prepared by the grafting of an organometallic compound of said group IIa, IVb, IIb, IVa metals.The catalyst is particularly suitable for the isomerization of an aromatic C.sub.8 cut.

Abstract: For the at least partial separation of aliphatic paraffins into at least one effluent comprising the least branched paraffins and at least one effluent comprising the most branched paraffins, use is made of at least one adsorbent bed comprising at least one grafted microporous solid. A preferred use of the invention relates to the treatment of a charge obtained from an isomerization zone, whereby at least one adsorbent bed makes it possible to separate the charge into a first effluent comprising the normal paraffins and a second effluent, and at least one adsorbent bed on which passes the second effluent, comprising at least one grafted microporous solid, making it possible to obtain a third effluent comprising the monomethyl branched paraffins and a fourth effluent comprising the polymethyl branched paraffins.

Abstract: The invention relates to a catalyst for isomerization of a C8 aromatic cut containing a mordenite characterized in that said mordenite contains at least one metal of groups IIa, IVb, IIb or IVa and is such that:its overall Si/Al atomic ratio is between 6 and 15,its sodium content by weight relative to the weight of dry mordenite is less than 2000 ppm,its elementary mesh volume is between 2.725 and 2.785 nm.sup.3,its n-hexane adsorption capacity is greater than 0.065 cm.sup.3 of liquid/gram,its isooctane adsorption capacity is less than 0.068 cm.sup.3 of liquid/gram.The invention also relates to the preparation of this mordenite by grafting on an H-shaped mordenite of at least one organometallic compound of said metal.

Abstract: The invention relates to a catalyst for isomerization of a C8 aromatic cut containing a mordenite characterized in that said mordenite contains at least one metal of groups IIa, IVb, IIb or IVa and is such that:its overall Si/Al atomic ratio is between 6 and 15,its sodium content by weight relative to the weight of dry mordenite is less than 2000 ppm,its elementary mesh volume is between 2.725 and 2.785 nm.sup.3,its n-hexane adsorption capacity is greater than 0.065 cm.sup.3 of liquid/gram,its isooctane adsorption capacity is less than 0.068 cm.sup.3 of liquid/gram.The invention also relates to the preparation of this mordenite by grafting on an H-shaped mordenite of at least one organometallic compound of said metal.