Zeolite beta and process for producing the same
View Patent ↗A zeolite beta according to the present invention has a SiO 2 /Al 2 O 3 ratio of 10 to 16 and is aluminum-rich. The zeolite beta has a BET specific surface area measured in the state of a sodium type of 500 to 700 m 2 /g, a micropore specific surface area of 350 to 500 m 2 /g, and a micropore volume of 0.15 to 0.25 cm 3 /g.
1. A zeolite beta having a SiO 2 /Al 2 O 3 ratio of 10 to 16, wherein
a BET specific surface area measured in the state of a sodium type is 500 to 700 m 2 /g, a micropore specific surface area is 350 to 500 m 2 /g, and a micropore volume is 0.15 to 0.25 cm 3 /g.
2. A process for producing a zeolite beta, comprising the steps of:
(1) mixing a silica source, an alumina source, an alkali source, and water to obtain a reaction mixture having a composition represented by molar ratios below:
SiO 2 /Al 2 O 3 =40 to 200
Na 2 O/SiO 2 =0.22 to 0.4
H 2 O/SiO 2 =10 to 50,
(2) adding a zeolite beta having a SiO 2 /Al 2 O 3 ratio of 8 to 30 and containing no organic compound having an average particle size of not less than 150 nm used as a seed crystal to the reaction mixture in a proportion of 0.1 to 20% by weight based on the silica component in the reaction mixture, and
(3) hermetically heating the reaction mixture containing the seed crystal added to 100 to 200° C.
3. The process for producing a zeolite beta according to claim 2 , comprising the steps of:
(1) mixing a silica source, an alumina source, an alkali source, and water to obtain a reaction mixture having a composition represented by molar ratios below:
SiO 2 /Al 2 O 3 =44 to 200
Na 2 O/SiO 2 =0.24 to 0.35
H 2 O/SiO 2 =15 to 25,
(2) adding a zeolite beta having a SiO 2 /Al 2 O 3 ratio of 8 to 30 and containing no organic compound having an average particle size of not less than 150 nm used as a seed crystal to the reaction mixture in a proportion of 0.1 to 20% by weight based on the silica component of the reaction mixture, and
(3) hermetically heating the reaction mixture containing the seed crystal added to 120 to 180° C.
4. The production process according to claim 2 , wherein the zeolite beta produced by the production process according to claim 2 is used as the seed crystal.
5. The production process according to claim 2 , wherein the reaction mixture is aged under a temperature of 20 to 80° C. before heating the reaction mixture.
6. The production process according to claim 2 , wherein the reaction mixture is stirred in the step of hermetically heating the reaction mixture.
7. A catalyst for purging exhaust gas for internal combustion engines, the catalyst comprising the zeolite beta according to claim 1 .