Zeolite ITQ-3

Details Zeolite ITQ-3 Zeolite ITQ-3

2000-02-28

2002-12-31

Sample, David (Department: 1755)

Chemistry of inorganic compounds

Zeolite

Organic compound used to form zeolite

C423S709000, C423S718000, C423S335000, C208S120010, C208S130000, C208S135000, C208S31000R, C585S639000, C585S640000, C585S648000, C585S649000, C585S650000

Reexamination Certificate

active

06500404

ABSTRACT:

TECHNICAL FIELD
Microporous Crystalline Materials
BACKGROUND
Zeolites are microporous crystalline materials of variable composition characterized by a TO
4
tetrahydra crystalline lattice (wherein T represents atoms in the formal oxidation state of +3 or +4, such as for example Si, Ti, Al, Ge, B, Ga
which all share their vertexes giving rise to a three-dimensional structure containing channels and/or cavities of molecular dimensions. When some of the atoms T have an oxidation state lower than +4, the crystalline lattice formed has negative charges which are compensated by the presence of organic or inorganic cations in the channels or cavities. Organic molecules and H
2
O can also be located in these channels and cavities, so in general, the chemical composition of zeolites can be represented by the following empirical formula:
X(M
1

XO
2
):yYO
2
:SiO
2
wherein M is one or several organic or inorganic cations with charge +n; X is one or several trivalent elements; Y is one or several tetravalent elements, generally Si; and R is one or several organic substances. Although the nature of M, X, Y and R and the values of x, y, z and w can, in general, be varied by means of post-synthesis treatments, the chemical composition of a zeolite (just as it is synthesized or after calcination thereof) has a range characteristic of each zeolite and its preparation method.
On the other hand, a zeolite is also characterized by its crystalline structure, which defines a system of channels and cavities and gives rise to a specific X-ray diffraction pattern. In this way, zeolites are differentiated from each other by their range of chemical composition plus their X-ray diffraction pattern. Both characteristics (crystalline structure and chemical composition) also determine the physicochemical properties of each zeolite and the applicability thereof in different industrial processes.
DESCRIPTION OF THE INVENTION
The present invention refers to a microporous crystalline material of zeolitic nature named ITQ-3, 5
to
its method of obtainment and to its applications.
The material is characterized by its chemical composition and its X-ray diffraction pattern. In its anhydrous and calcined formed, the chemical composition of ITQ-3 may be represented by the empirical formula:
X(M
1

XO
2
):yYO
2
:SiO
2
wherein x has a value lower than 0.15; it may be equal to zero; and y has a value lower than 0, 1; it may be equal to zero; M is H
+
or an inorganic cation of charge +n; X is a chemical element with oxidation state (Al, Ge, B, Cr) and Y is a chemical element with oxidation state +4 (Ti, Ge, V), when x=0 and y=0 the material can be described as a new polymorphous of silica of microporous nature. In the preferred embodiment of the present invention, ITQ-3 has the composition, in a calcined and anhydrous state
x(HXO
2
):SiO
2
wherein X is a trivalent element and x has a value lower than 0.1 and may be equal to zero, in which case the material may be described by means of the formula SiO
2
. However, it is possible, in terms of the synthesis method and the calcination or subsequent treatments, the existence of defects in the crystalline lattice, manifested by the presence of Si—OH groups (silanols). These defects have not been included in the above empirical formulae. In a preferred embodiment of the present invention, ITQ-3 has a very low concentration of this type of defect (silanol concentration lower than 15% with respect to the total Si atoms, preferably lower than 6%, measured by nuclear magnetic resonance spectroscopy of
29
Si in spinning angle).
The X-ray diffraction pattern of ITQ-3 just as it is synthesized as obtained by the powder method using a variable divergence slit and the Cu K&agr; radiation, is characterized by the following values of 2
&thgr;
angles and relative intensities (I/I
O
):
TABLE I
2&thgr;
I/I
o
(°)
(%)
 8.54
100 
 9.28
85
10.07
15
11.04
 5
12.41
 5
13.60
 7
14.17
 3
15.70
14
17.02
11
17.58
15
18.10
85
18.84
20
19.29
30
19.56
30
20.20
65
20.35
70
20.94
25
22.08
 5
22.25
 5
22.93
 5
23.21
 5
23.73
60
23.90
20
24.07
35
24.11
25
24.47
25
25.04
90
25.49
45
26.12
10
26.63
 8
27.14
10
27.83
10
28.23
10
28.85
10
29.08
10
30.33
20
31.53
25
32.43
15
32.84
20
34.37
 5
The positions and relative intensities of the peaks depend to a certain degree on the chemical composition of the material (the pattern represented in Table I refers to the material whose lattice is exclusively comprised of silicon oxide, SiO
2
and synthesized using a quaternary ammonium cation as a structure-directing agent). The relative intensities may also be affected by phenomena of preferred orientation of the crystals, produced during preparation of the sample, while the precision in the interplanar spacing measurement depends on the quality of alignment of the goniometer. Moreover, calcination can yield significant changes in the X-ray diffraction pattern, due to the removal of organic compounds retained during synthesis in the zeolite pores, so that Table II represents the X-ray diffraction pattern of ITQ-3 of calcined ITQ-3 of composition SiO
2
is represented:
TABLE II
I/I
o
2&thgr;
(%)
 8.66
100 
 9.10
82
10.14
32
11.08
 4
12.51
 6
15.87
 4
16.93
 6
17.26
 5
17.81
 7
18.27
46
18.81
 9
19.51
17
20.10
21
20.38
11
20.74
10
22.17
 9
22.26
 8
23.90
 9
24.04
12
24.17
15
24.27
11
24.42
10
24.84
10
25.12
40
25.52
 7
25.62
 7
27.23
 8
27.53
 5
27.91
 4
28.12
 4
28.27
 5
28.48
 4
28.67
 6
30.54
10
30.83
 6
31.13
 7
31.79
13
32.48
 6
32.84
 4
33.06
 8
33.46
 3
33.48
 3
34.15
 4
34.26
 4
34.64
 3
34.77
 3
The present invention also refers to the method of preparation of ITQ-3. This comprises thermal treatment at temperatures between 80 and 200° C., preferably between 130 and 180° C., of a reaction mixture that contains a source of SiO
2
(such as, for example, tetraethylorthosilicate, colloidal silica, amorphous silica), an organic cation in hydroxide form, preferably N,N-dimethyl-6-azonium-1,3,3-trimethylbicyclo(3.2.1)octane (I) hydroxide, hydrofluoric acid and water. Alternatively, it is possible to use the organic cation as a salt (for example, a halide, preferably chloride) and to substitute hydrofluoric acid by a fluoride salt, preferably NH
4
F. The reaction mixture is characterized by its relatively low ph<12, preferably<11, and which may also be neutral or slightly acidic.
Optionally, it is possible to add a source of another tetravalent element Y and/or trivalent element X, preferably Ti or Al. The addition of this element may be done before heating the reaction mixture or in an intermediate time during said heating. Occasionally, it may be convenient to add also in a certain time during the preparation of ITQ-3 crystals (up to 15% by weight with respect to the total inorganic oxides, preferably up to 10% by weight) as cryst6allizer promoters (seeding). The composition of the reaction mixture in oxide form responds to the general formula
RR
2
O:aHF:xHXO
2
:yYO
2
:SiO
2
:wH
2
O
wherein X is one or several trivalent elements, preferably Al; Y is one or several tetravalent elements; R is an organic cation, preferably N,N-dimethyl-6-azonium-1,3,-trimethyl-6-bicyclo(3.2.1.)octane, and the values of r,a,x,y and w are in the ranges
R=0.05-1.0, preferably 0.1-0-75
A=0-1.5, preferably 0.1-1.5
X=0-0.15
Y=0-0.1
W=3-100, preferably 5-50, more preferably 7-50
The thermal treatment of the reaction mixture may be done in static or with stirring of the mixture. Once the crystallization is finished the solid product is separated and dried. Subsequent calcination at temperatures between 400 and 650° C., preferably between 450 and 600° C., produces the decomposition of the organic residue occluded in the zeolite and renders the free zeolitic channels.
This method of synthesis of ITQ-3 zeolite has the peculiarity

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