Method for preparing a nanometric zeolite y

Method for preparation of a FAU-structural-type nanometric zeolite Y that has a crystal size of less than 100 nm and an Si/Al ratio that is greater than 2, with said method comprising at least the following steps:

• i) The mixing, in aqueous medium, of at least one AO2 source of at least one tetravalent element A that is selected from among silicon, germanium, titanium by itself or in a mixture, at least one BOb source of at least one trivalent element B that is selected from among aluminum, boron, iron, indium, gallium, by itself or in a mixture, at least one C2/mO source of an alkaline metal or alkaline-earth metal C selected from among lithium, sodium, potassium, calcium, magnesium by itself or in a mixture, with said C2/mO source of alkaline metal or alkaline-earth metal C also comprising at least one hydroxide ion source for obtaining a gel, with the reaction mixture having the following molar composition:
• vAO2:wBOb:xC2/mO:yH2O
• with v being between 1 and 40,
• with w being between 0.1 and 5,
• with x being between 1 and 40,
• with y being between 30 and 1000,
• with b being between 1 and 3, b being a whole number or a rational number,
• with m being equal to 1 or 2,
• ii) the curing of the gel obtained at the end of step (i) at a temperature of between −15° C. and 60° C., with or without stirring, for a time period of between 1 and 60 days,
• iii) after at least 3 days of curing, the one-time or repeated addition of at least one AO2 source of at least one tetravalent element A that is selected from among silicon, germanium, titanium, by itself or in a mixture, in said gel, with the molar composition of the gel at the end of the addition being as follows:
• vAO2:wBOb:xC2/mO:yH2O
• with v being between 5 and 50,
• with w being between 0.1 and 5,
• with x being between 1 and 40,
• with y being between 200 and 1000,
• with b being between 1 and 3, b being a whole number or a rational number,
• with m being equal to 1 or 2,
• (iv) the hydrothermal treatment of the gel that is obtained at the end of step (iii) at a temperature of between 20° C. and 200° C., under autogenous reaction pressure, for a time period of between 1 hour and 14 days, to obtain the crystallization of said FAU-structural-type nanometric zeolite Y.