Method of preparing zeolite nanosheet via simple calcination process and zeolite nanosheet particle prepared thereby
Disclosed are a method of preparing a zeolite nanosheet and a zeolite nanosheet particle prepared thereby, and more particularly a method of preparing a zeolite nanosheet capable of preparing a monolayer zeolite nanosheet through a simple process of mixing a multilayer zeolite precursor with a swelling agent to swell the multilayer zeolite precursor and drying and calcining the multilayer zeolite precursor, wherein the monolayer zeolite nanosheet is useful to separate a catalyst or gas, and a zeolite nanosheet particle prepared thereby.
1. A method of preparing a monolayer zeolite nanosheet comprising:
mixing a multilayer MWW type zeolite precursor with water and a swelling agent to swell intra-layers of the multilayer zeolite precursor;
recovering a solid material from the mixture containing a swollen zeolite precursor, and then calcining the solid material to obtain a monolayer zeolite nanosheet; and
drying at a temperature of 50 to 110° C. for 10 to 24 hours after the recovering the solid material,
wherein the swelling agent is a mixture of a salt compound having a functional group of alkyltrimethylammonium and a salt compound having a functional group of tetrapropylammonium, and
wherein an Si/AI ratio of the multilayer MWW type zeolite precursor is 10 to 200.
2. The method of preparing a monolayer zeolite nanosheet of claim 1 , wherein the salt compound having the functional group of alkyltrimethylammonium is one or more selected from the group consisting of dodecyltrimethylammonium bromide, cetrimonium bromide and trimethyloctadecylammonium bromide.
3. The method of preparing a monolayer zeolite nanosheet of claim 1 , wherein the salt compound having the functional group of tetrapropylammonium is one or more selected from the group consisting of tetrapropylammonium bromide, tetrapropylammonium fluoride, tetrapropylammonium chloride and tetrapropylammonium hydroxide.
4. The method of preparing a monolayer zeolite nanosheet of claim 1 , wherein the mixing is performed at a temperature of 25 to 80° C. for 16 to 20 hours.
5. The method of preparing a monolayer zeolite nanosheet of claim 1 , wherein the calcining is performed at a temperature of 400 to 700° C. for 1 to 40 hours.
6. The method of preparing a monolayer zeolite nanosheet of claim 1 , wherein the multilayer MWW type zeolite precursor is prepared by adding an organic structure-directing agent.
7. The method of preparing a monolayer zeolite nanosheet of claim 1 , wherein a half-width at half-maximum (HWHM) of a (101) plane of the monolayer zeolite nanosheet shows linear behavior with respect to a reciprocal of a number of unit cell nanosheets of the zeolite in a c-direction.
8. The method of preparing a monolayer zeolite nanosheet of claim 1 , wherein a ratio of a micropore volume of the monolayer zeolite nanosheet shows linear behavior with respect to a reciprocal of a number of unit cell nanosheets of the zeolite in a c-direction.
9. A monolayer zeolite nanosheet prepared by the method according to claim 1 , wherein particles having about one or two unit cell thickness, are aggregated into the monolayer zeolite nanosheet having about three to four unit cell thickness along c-axis.
10. A catalyst comprising the monolayer zeolite nanosheet of claim 9 .
11. A method of separating H 2 comprising contacting the monolayer zeolite nanosheet of claim 9 with a mixture containing H 2 to separate H 2 from the mixture.