Beta zeolite and method for producing same
The present invention provides a beta zeolite that is useful as a catalyst, adsorbent agent, or the like, and that is both microporous and mesoporous. The beta zeolite is characterized by (i) the SiO 2 /Al 2 O 3 ratio being 8-30, and the SiO 2 /ZnO ratio being 8-1000, (ii) the micropore surface area being 300-800 m 2 /g, (iii) the micropore volume being 0.1-0.3 cm 3 /g, and (iv) having mesopores having, in the state as synthesized, a diameter of 2-6 nm and a volume of 0.001-0.3 cm 3 /g. The beta zeolite is favorably produced by means of adding and reacting a zinc silicate beta zeolite as a seed crystal with a reaction mixture containing a silica source, an alumina source, an alkali source, and water.
1. A beta zeolite in which:
(i) a SiO 2 /Al 2 O 3 ratio ranges from 8 to 30, and a SiO 2 /ZnO ratio ranges from 8 to 1000;
(ii) a micropore surface area ranges from 300 to 800 m 2 /g;
(iii) a micropore volume ranges from 0.1 to 0.3 cm 3 /g; and
(iv) in an as-synthesized state, a diameter of a mesopore ranges from 2 to 6 nm, and a volume of the mesopore ranges from 0.001 to 0.3 cm 3 /g.
2. A method for producing a beta zeolite comprising:
(1) mixing a silica source, an alumina source, an alkali source, and water so as to be a reaction mixture having a composition represented by a molar ratio given below;
SiO 2 /Al 2 O 3 =8 to 300
Na 2 O/SiO 2 =0.05 to 0.6
H 2 O/SiO 2 =5 to 50
(2) using the beta zeolite, which has a SiO 2 /ZnO ratio ranging from 4 to 50, a SiO 2 /Al 2 O 3 ratio that is equal to or more than 4, and a mean particle size that is equal to or more than 100 nm, as a seed crystal without being fired, and adding the beta zeolite to the reaction mixture at a rate of 0.1 to 20% by weight with respect to a silica component in the reaction mixture; and
(3) airtightly heating the reaction mixture to which the seed crystal is added at 80 to 200° C.
3. The method according to claim 2 , further comprising
aging the reaction mixture under a temperature of 20 to 100° C. prior to heating the reaction mixture.
4. The method according to claim 3 , wherein the reaction mixture is agitated in the airtightly heating process.
5. The method according to claim 2 , wherein the reaction mixture is agitated in the airtightly heating process.