ZEOLITE, PRODUCTION METHOD THEREOF, HYDROCARBON ADSORBENT AND EXHAUST GAS PURIFYING CATALYST
Provided are zeolite which, even in a severe thermal environment, maintains the hydrocarbon adsorbency and has increased catalytic reactivity and improved heat resistance, a production method thereof, a hydrocarbon adsorbent and an exhaust gas purifying catalyst. The zeolite is a zeolite having large pores with 12-member rings in a framework structure and encapsulating metal-containing particles. The metal contained in the metal-containing particles preferably contains at least one of metals selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Sn, Zr, Rh, Ru, Pd, Pt, Ag, Ir, Au, Nb and Mo.
1 . A zeolite, having large pores with 12-member rings in a framework structure, and encapsulating metal-containing particles.
2 . The zeolite according to claim 1 , wherein the zeolite is at least one of zeolites selected from the group consisting of BEA type zeolite, MSE type zeolite, MTW type zeolite, CON type zeolite, FAU type zeolite, MOR type zeolite and EON type zeolite.
3 . The zeolite according to claim 1 , wherein a metal contained in the metal-containing particles contains at least one of metals selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Sn, Zr, Rh, Ru, Pd, Pt, Ag, Ir, Au, Nb and Mo.
4 . The zeolite according to claim 1 , wherein a mean diameter of the 100 metal-containing particles analyzed from the transmission electron microscopic images is in a range of 0.1 nm or larger and 30 nm or smaller, wherein a mean value of the length and the breadth of the metal-containing particles is measured as a diameter of the metal-containing particles from the transmission electron microscopic image.
5 . The zeolite according to claim 1 , wherein the metal-containing particles have a metal content in the range of 0.2% by mass or higher and 11.0% by mass or lower with respect to a total amount of the zeolite encapsulating the metal-containing particles.
6 . The zeolite according to claim 1 , wherein the zeolite has a SiO 2 /Al 2 O 3 molar ratio in the range of 20 or higher and 4,000 or lower.
7 . The zeolite according to claim 1 , wherein the zeolite comprises an A atom; the A atom is at least one of atoms selected from the group consisting of B, Ga, Ge, Zr, Cu, Fe, Zn, Sn, P, Co, Mn, Cr and Hf; and the zeolite has an (Al+A)/Si atomic ratio in the range of 0.02 or higher and 1.0 or lower as a ratio of a total of Al and the A atom with respect to silicon (Si) contained in the zeolite.
8 . A hydrocarbon adsorbent, comprising the zeolite according to claim 1 .
9 . An exhaust gas purifying catalyst, comprising a catalyst support, and a hydrocarbon adsorbing part comprising the hydrocarbon adsorbent according to claim 8 and formed on the catalyst support.
10 . A method for producing a zeolite, comprising:
a step of preparing a reaction mixture containing a silica source, an alumina source, an organic structure-directing agent, a metal-containing particle source, water and as required, an alkali metal source;
a step of heating the reaction mixture to obtain a crystallized powder; and
a step of heating the crystallized powder to remove the organic structure-directing agent to thereby obtain the zeolite having large pores with 12-member rings in a framework structure and encapsulating metal-containing particles,
wherein the reaction mixture has a composition represented by the following molar ratio or atomic ratio, and contains 0.1% by mass or more and 12% by mass or less of a metal contained in the metal-containing particle source with respect to a total amount of a solid content of the reaction mixture:
organic
structure
-
directing
agent
/
Si
molar
ratio
=
0.1
or
higher
and
0.9
or
lower
;
SiO
2
/
Al
2
O
3
molar
ratio
=
2
or
higher
and
200
,
TagBox[",", "NumberComma", Rule[SyntaxForm, "0"]]
000
or
lower
;
and
alkali
metal
/
Si
atomic
ratio
=
0
or
higher
and
0.5
or
lower
.
11 . The method for producing a zeolite according to claim 10 , wherein the method comprises a step of reducing the zeolite encapsulating metal-containing particles using a reducing agent.
12 . A method for producing a zeolite, comprising:
a step of preparing a reaction mixture containing a silica source, an alumina source, an organic structure-directing agent, a metal-containing particle source, a reducing agent, water and as required, an alkali metal source;
a step of heating the reaction mixture to obtain a crystallized powder; and
a step of heating the crystallized powder to remove the organic structure-directing agent to thereby obtain the zeolite having large pores with 12-member rings in a framework structure and encapsulating metal-containing particles,
wherein the reaction mixture has a composition represented by the following molar ratio or atomic ratio, and contains 0.1% by mass or more and 12% by mass or less of a metal contained in the metal-containing particle source with respect to a total amount of a solid content of the reaction mixture:
organic
structure
-
directing
agent
/
Si
molar
ratio
=
0.1
or
higher
and
0.9
or
lower
;
SiO
2
/
Al
2
O
3
molar
ratio
=
2
or
higher
and
200
,
TagBox[",", "NumberComma", Rule[SyntaxForm, "0"]]
000
or
lower
;
and
alkali
metal
/
Si
atomic
ratio
=
0
or
higher
and
0.5
or
lower
.
13 . The method for producing a zeolite according to claim 10 , wherein the method comprises a step of ion-exchanging the zeolite encapsulating the metal particles in the pores using an acid or an ammonium salt.
14 . The method for producing a zeolite according to claim 10 , wherein the reaction mixture comprises an A atom source; an A atom is at least one of atoms selected from the group consisting of B, Ga, Ge, Zr, Cu, Fe, Zn, Sn, P, Co, Mn, Cr and Hf; and the reaction mixture has a composition represented by the following atomic ratio of a total of Al and the A atom with respect to Si in the reaction mixture:
(
Al
+
A
)
/
Si
atomic
ratio
=
0.001
or
higher
and
0.06
or
lower
.
15 . The method for producing a zeolite according to claim 10 , wherein a metal contained in the metal-containing particle source contains at least one of metals selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Sn, Zr, Rh, Ru, Pd, Pt, Ag, Ir, Au, Nb and Mo.
16 . The method for producing a zeolite according to claim 12 , wherein a metal contained in the metal-containing particle source contains at least one of metals selected from the group consisting of Rh, Ru, Pd, Pt, Ag, Ir and Au.