Process for the preparation of agglomerated zeolites X and LSX exchanged with lithium

Process for the preparation of zeolites of X type having an Si/Al atomic ratio of less than or equal to 1.5, the exchangeable cations of which comprise, referred to as equivalents:

• from approximately 50 to approximately 99% of lithium ions,
• from approximately 4 to approximately 50% of trivalent ions selected from aluminum, scandium, gallium, iron (III), chromium (III), indium, yttrium, lanthanides or rare earth metals, alone or as mixtures, and/or of divalent ions selected from calcium, strontium, zinc, copper, chromium (II), iron (II), manganese, nickel or cobalt, alone or as a mixture,
• 0 to approximately 15% of residual ions selected from sodium, potassium, ammonium or hydronium, alone or as a mixture,
• agglomerated with a binder,
• according to which a portion of the exchangeable cations of an agglomerated zeolite of X type, the exchangeable cations of which are sodium, potassium, ammonium and/or hydronium cations and/or di- and/or trivalent cations, is exchanged with lithium, wherein the process comprises:
• (a) providing a starting zeolite, the starting zeolite being an agglomerated zeolite of X type comprising exchangeable cations selected from the group consisting of sodium, potassium, ammonium, hydronium, divalent and trivalent cations;
• (b) providing a plurality of receptacles arranged in series in an interchangeable manner to form a carrousel;
• (c) filling each of the receptacles with portions of the starting zeolite;
• (d) introducing a first solution of at least one lithium compound through an inlet formed in a first receptacle in the carousel and percolating said first solution successively through each of the receptacles in the carrousel, the solution coming into contact with the starting zeolite portions disposed in the receptacles such that exchange of the lithium and the exchangeable cations occurs;
• (e) through an outlet formed in the first receptacle, drawing a lithium-containing bleed off from a stream formed in the first receptacle by the contact between the solution of the at least one lithium compound and the starting zeolite, said lithium-containing bleed containing excess lithium;
• (f) through an outlet formed in a final receptacle in the series of receptacles, drawing off a final effluent stream formed by the solution of the at least one lithium compound percolating through said carrousel in contact with said starting zeolite, said final effluent stream comprising compounds comprising the exchangeable cations from the starting zeolite and traces of the at least one lithium compound;
• and
• (g) modifying the sequence of receptacles in the carrousel in cycles, each cycle comprising the percolation of the solution of the at least one lithium compound from the first receptacle to the final receptacle in the carrousel and resulting in a desired degree of lithium exchange for the starting zeolite in the first receptacle, wherein said modifying of the sequence of receptacles after each cycle involves:
• (i) removing said first receptacle from the carousel;
• (ii) washing the lithium-containing zeolite in the first receptacle to free the zeolite of the solution of the at least one lithium compound;
• (iii) optionally replacing the lithium-containing zeolite in the first receptacle with a second starting zeolite;
• (iv) introducing a second solution of at least one second lithium compound into an inlet of a second receptacle disposed successively to the first receptacle in the carousel and percolating said second solution through the carrousel, the percolation through the second receptacle forming a second lithium-containing zeolite;
• (v) washing the second lithium-containing zeolite in the second receptacle to free the zeolite of the second solution of the at least one second lithium compound;
• (vi) optionally replacing the second lithium-containing zeolite in the second receptacle with a third starting zeolite;
• and
• (vii) optionally, repeating steps (i)-(iii) for each of the receptacles in the carrousel.