Zeolite production method
Disclosed is a method for readily and inexpensively producing zeolite without using an organic structure-directing agent (organic SDA). Specifically disclosed is a method whereby a gel containing a silica source, an alumina source, an alkaline source and water is reacted with zeolite seed crystals, to produce a zeolite with the same kind of skeletal structure as the zeolite. The gel used is a gel of a composition whereby, when a zeolite is synthesized from this gel only, the synthesized zeolite comprises at least one of the kinds of composite building units of the target zeolite.
1. A method of producing a zeolite comprising:
reacting a gel and zeolite seed crystals to produce a zeolite having the same kind of skeletal structure as the zeolite seed crystals;
wherein:
the gel comprises a silica source, an alumina source, an alkali source and water;
the gel is capable of synthesizing a zeolite without the use of the zeolite seed crystals, wherein the zeolite synthesized without the use of the zeolite seed crystals has a different kind of skeletal structure than the zeolite seed crystals and comprises one or more building units of zeolite;
the zeolite seed crystals comprise one or more composite building units of zeolite;
the zeolite seed crystals and the zeolite synthesized without the use of zeolite seed crystals comprise at least one equivalent composite building unit of zeolite;
MFI zeolite, MEL zeolite, MSE zeolite, MTW zeolite, TUN zeolite, MFS zeolite, MOZ zeolite, EON zeolite, or LTF zeolite is used as the zeolite seed crystals;
and wherein the reacting step occurs without the use of an organic structure-directing agent.
2. The method of producing a zeolite according to claim 1 ,
wherein the zeolite produced is MFI zeolite,
MFI zeolite is used as the zeolite seed crystals, and
the gel has a composition which forms a mordenite zeolite, when the zeolite is synthesized from the gel without the use of the zeolite seed crystals.
3. The method of producing a zeolite according to claim 2 ,
wherein a gel having a composition shown in the following (a) or (b) is used as the gel,
(a)
SiO 2 /Al 2 O 3 =40 to 200,
Na 2 O/SiO 2 =0.24 to 0.4,
H 2 O/SiO 2 =10 to 50,
(b)
SiO 2 /Al 2 O 3 =10 to 40,
Na 2 O/SiO 2 =0.05 to 0.25,
H 2 O/SiO 2 =5 to 50.
4. The method of producing a zeolite according to claim 3 ,
wherein, as a post treatment, dealumination of the zeolite is carried out by mixing the zeolite and an aqueous solution of citric acid or a salt thereof, and heating a mixed aqueous solution under an autogenous pressure.
5. The method of producing a zeolite according to claim 2 ,
wherein, as a post treatment, dealumination of the zeolite is carried out by mixing the zeolite and an aqueous solution of citric acid or a salt thereof, and heating a mixed aqueous solution under an autogenous pressure.
6. The method of producing a zeolite according to claim 1 ,
wherein the zeolite produced is MEL zeolite,
MEL zeolite is used as the zeolite seed crystals, and
the gel has a composition which forms a mordenite zeolite, when the zeolite is synthesized from the gel without the use of the zeolite seed crystals.
7. The method of producing a zeolite according to claim 6 ,
wherein a gel having a composition shown in the following (a) or (b) is used as the gel,
(a)
SiO 2 /Al 2 O 3 =40 to 200,
Na 2 O/SiO 2 =0.24 to 0.4,
H 2 O/SiO 2 =10 to 50,
(b)
SiO 2 /Al 2 O 3 =10 to 40,
Na 2 O/SiO 2 =0.05 to 0.25,
H 2 O/SiO 2 =5 to 50.
8. The method of producing a zeolite according to claim 7 ,
wherein, as a post treatment, dealumination of the zeolite is carried out by mixing the zeolite and an aqueous solution of citric acid or a salt thereof, and heating a mixed aqueous solution under an autogenous pressure.
9. The method of producing a zeolite according to claim 6 ,
wherein, as a post treatment, dealumination of the zeolite is carried out by mixing the zeolite and an aqueous solution of citric acid or a salt thereof, and heating a mixed aqueous solution under an autogenous pressure.
10. The method of producing a zeolite according to claim 1 ,
wherein the zeolite produced is MSE zeolite,
MSE zeolite is used as the zeolite seed crystals, and
the gel has a composition which forms a mordenite zeolite, when the zeolite is synthesized from the gel without the use of the zeolite seed crystals.
11. The method of producing a zeolite according to claim 10 ,
wherein a gel having a composition shown in the following (a) or (b) is used as the gel,
(a)
SiO 2 /Al 2 O 3 =40 to 200,
(Na 2 O+K 2 O)/SiO 2 =0.24 to 0.4,
K 2 O/(Na 2 O+K 2 O)=0 to 0.7,
H 2 O/SiO 2 =10 to 50,
(b)
SiO 2 /Al 2 O 3 =10 to 40,
(Na 2 O+K 2 O)/Sio 2 =0.05 to 0.25,
K 2 O/(Na 2 O+K 2 O)=0 to 0.7,
H 2 O/SiO 2 =5 to 50.
12. The method of producing a zeolite according to claim 10 ,
wherein, as a post treatment, dealumination of the zeolite is carried out by mixing the zeolite and an aqueous solution of citric acid or a salt thereof, and heating a mixed aqueous solution under an autogenous pressure.
13. The method of producing a zeolite according to claim 1 ,
wherein the zeolite produced is MTW zeolite,
MTW zeolite is used as the zeolite seed crystals, and
the gel has a composition which forms an MFI zeolite, when the zeolite is synthesized from the gel without the use of the zeolite seed crystals.
14. The method of producing a zeolite according to claim 13 ,
wherein a gel having a composition shown below is used as the gel,
SiO 2 /Al 2 O 3 =10 to 150,
Na 2 O/SiO 2 =0.075 to 0.23,
H 2 O/SiO 2 =5 to 50.
15. The method of producing a zeolite according to claim 1 ,
wherein, as a post treatment, dealumination of the zeolite is carried out by mixing the zeolite and an aqueous solution of citric acid or a salt thereof, and heating a mixed aqueous solution under an autogenous pressure.