Process for synthesizing zeolite crystals with seeding agent
The present invention relates to process for synthesizing zeolite X crystals comprising at least one step of adding seeding agent(s) into a synthesis gel and at least one step of forming zeolite X crystals at a temperature strictly greater than 120° C., preferably equal to or greater than 130° C.
1. A process for synthesizing zeolite X crystals comprising comprising:
at least one step of adding seeding agent(s) into a synthesis gel; and
at least one step of forming zeolite X crystals at a temperature equal to or greater than 130° C.
2. The process according to claim 1 , comprising at least the following steps:
a) preparing a synthesis gel by mixing at least one source of silica, at least one source of alumina and optionally, at least one aqueous alkali or alkaline-earth metal hydroxide solution,
b) mixing said synthesis gel with at least one seeding agent in order to obtain a reaction medium,
c) introducing the reaction medium into a crystallization reactor,
d) carrying out the crystallization at a temperature equal to or greater than 130° C.,
e) filtering the reaction medium in order to recover the zeolite X crystals produced.
3. The process according to claim 2 , wherein the crystallization temperature is equal to or less than 200° C.
4. The process according to claim 1 , wherein the reaction medium is introduced into the crystallization reactor at a temperature equal to or greater than 50° C.
5. The process according to claim 2 , wherein the difference between the crystallization temperature and the temperature of the reaction medium (Tc−Tr) is between 0° C. and 100° C., limits included.
6. The process according to claim 1 , wherein the zeolite crystals prepared are zeolite X crystals having an Si/AI atomic ratio of between 1.00 and 1.45, limits included.
7. The process according to claim 1 , wherein the seeding agent is chosen from nucleating gels, zeolite crystals, mineral particles, and mixtures thereof.
8. The process according to claim 1 , wherein the total amount of seeding agent(s) added represents between 0.005% and 10% by weight relative to the synthesis gel.
9. The process according to claim 1 , wherein the crystallization reaction is carried out at a pressure between atmospheric pressure and 1.5 MPa.
10. The process according to claim 1 , wherein the process is conducted continuously, and wherein the crystallization is carried out in a tubular reactor provided with an oscillatory device.