β-zeolite and production method thereof

Abstract

Provided is a β-zeolite that has an SiO.sub.2/Al.sub.2O.sub.3 ratio of less than 20 but yet is comparable or superior in heat resistance to conventional β-zeolites having SiO.sub.2/Al.sub.2O.sub.3 ratio of 20 or greater. This β-zeolite is characterized in that: in powder X-ray diffractometry using a CuKα-ray as a ray source, the full width at half maximum of a powder X-ray diffraction peak on the (302) plane is 0.15-0.50 inclusive; and the molar ratio of silica to alumina is less than 20.0. Preferably, the β-zeolite is obtained by a production method which comprises a crystallization step for crystallizing a composition comprising an alumina source, a silica source, an alkali source, a tetraethylammonium cation source and water, characterized in that the composition contains potassium and the molar ratio of potassium to silica exceeds 0.04.

Claims

1. A β-zeolite, having a full width at half maximum of a powder X-ray diffraction peak of a (302) plane of 0.15 or more and 0.50 or less in powder X-ray diffraction measurement with a CuKα ray as radiation source, and a molar ratio of silica to alumina of less than 20.0.

2. The β-zeolite according to the claim 1, having a β-type structure content of 86% or more.

3. The β-zeolite according to claim 1, having a fluorine content of 100 ppm by weight or less.

4. The β-zeolite according to claim 1, having at least powder X-ray diffraction peaks below in powder X-ray diffraction measurement with a CuKα ray as radiation source: TABLE-US-00030 2 θ Relative intensity* 21.28°~21.40° 10 or more and 20 or less 22.33°~22.46° 100 25.22°~25.36° 10 or more and 20 or less 27.00°~27.12° 10 or more and 25 or less 29.42°~29.66° 10 or more and 25 or less wherein relative intensity is an intensity relative to peak intensity at 2θ=22.33 to 22.46°.

5. The β-zeolite according to claim 1, containing at least one of iron and copper.

6. A method for producing a β-zeolite, comprising crystallizing a composition containing an alumina source, a silica source, an alkali source, a tetraethylammonium cation source and water, wherein the composition contains potassium, and a molar ratio of potassium to silica is more than 0.04 and wherein the β-zeolite has a full width at half maximum of a powder X-ray diffraction peak of a (302) plane of 0.15 or more and 0.50 or less in powder X-ray diffraction measurement with a CuKα ray as radiation source, and a molar ratio of silica to alumina of less than 20.0.

7. The production method according to claim 6, wherein the alkali source is a potassium source.

8. The production method according to claim 6, wherein the composition has a molar composition below: SiO.sub.2/Al.sub.2O.sub.3 ratio=10.0 or more and 50.0 or less TEA/SiO.sub.2 ratio=0.03 or more and 0.30 or less K/SiO.sub.2 ratio=more than 0.04 and less than 0.70 Na/SiO.sub.2 ratio=0 or more and less than 0.10 H.sub.2O/SiO.sub.2 ratio=5.0 or more and 50.0 or less OH/SiO.sub.2 ratio=0.10 or more and 1.00 or less Seed crystal=0 wt % or more and 10 wt % or less.

9. A catalyst comprising the β-zeolite according to claim 1.

10. A method for reducing nitrogen oxides, comprising contacting the β-zeolite according to claim 1 with a nitrogen oxide-containing gas.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1(a) and FIG. 1(b) are schematic views showing a shape of a crystal particle of β-zeolite: FIG. 1(a) showing a double quadrangular frustum shape, FIG. 1(b) showing an approximately octahedron shape.

(2) FIG. 2 shows an XRD pattern of a crystallized product in Example 1.

(3) FIG. 3 shows an XRD pattern of a β-zeolite in Example 1.

(4) FIG. 4 shows an XRD pattern of a β-zeolite in Example 3.

(5) FIG. 5 shows an SEM observation view of a β-zeolite in Example 3 (scale in drawing: 1 μm).

(6) FIG. 6 shows an SEM observation view of a β-zeolite in Example 10 (scale in drawing: 1 μm).

(7) FIG. 7 shows an observation view of crystals of β-zeolite in Example 10 (scale in drawing: 100 nm).

(8) FIG. 8 shows an XRD pattern of a β-zeolite in Comparative Example 2.

(9) FIG. 9 shows an observation view of crystals of a β-zeolite in Comparative Example 3 (scale in drawing: 100 nm).

(10) FIG. 10 shows an XRD pattern of β-zeolite in Comparative Example 4.

(11) FIG. 11 shows an SEM observation view of β-zeolite in Comparative Example 4 (scale in drawing: 1 μm).

(12) FIG. 12 is a graph showing the nitrogen oxide reduction ratio of an iron-containing β-zeolite (colorless bar: fresh sample, solid black bar: 20-h aging sample)

EXAMPLES

(13) Hereinafter, the present invention will be more specifically described with reference to Examples and Comparative Examples. However, the present invention is not limited to the following Examples. The evaluation methods and the evaluation conditions are shown as follows.

(14) (Identification of Crystal)

(15) A powder X-ray diffractometer (apparatus name: Ultima IV, manufactured by Rigaku Corporation) was used to perform XRD measurement of the samples. The measurement conditions are as follows.

(16) Radiation source: CuKα ray (λ=1.5405 Angstrom)

(17) Measurement mode: step scan

(18) Scan condition: 40°/min

(19) Measurement time: 3 seconds

(20) Measurement range: 2θ=5° to 43°

(21) After the structure was identified by comparing the resulting XRD pattern with XRD patterns in U.S. Pat. No. 3,308,069, 2θ and FWHM of Peak.sub.(302), I.sub.(302) and I.sub.by-pro were determined.

(22) (Composition Analysis)

(23) A sample was dissolved in a mixed aqueous solution of hydrofluoric acid and nitric acid to prepare a sample solution. The sample solution was measured by inductively coupled plasma emission spectroscopy (ICP-AES) using an ICP apparatus (apparatus name: OPTIMA 5300 DV, manufactured by PerkinElmer, Inc.).

(24) (Average Crystal Particle Size)

(25) The sample was observed at a magnification of 15000 times using an electron microscope (apparatus name: JSM-6390 LV), and the horizontal Feret sizes of 150 primary crystal particles were measured. The obtained horizontal Feret sizes were averaged to obtain an average crystal particle size.

(26) (IR Spectrum)

(27) The IR spectrum was measured using an FT-IR apparatus (apparatus name: 660-IR, manufactured by Varian, Inc.) with a heat diffusivity reflection apparatus (apparatus name: ST 900° C. heat diffusivity reflection apparatus, manufactured by ST Japan Inc.) under the following conditions.

(28) Measurement Method: Heat Permeation Method Pretreatment: Temperature was retained at 500° C. for 2 hours under vacuum evacuation. Measurement was performed after the temperature was lowered to room temperature.

(29) Measurement temperature: 500° C.

(30) Measurement wave number range: 800 to 4000 cm.sup.−1

(31) Resolution: 2 cm.sup.−1

(32) Number of acquisitions: 128

Example 1

(33) After mixing a 35 wt % TEAOH aqueous solution, a 48 wt % potassium hydroxide aqueous solution, pure water and amorphous aluminosilicate (SiO.sub.2/Al.sub.2O.sub.3 ratio=18.2), a β-zeolite (product name: HSZ930NHA, manufactured by Tosoh Corporation) was added as seed crystal thereto by 1.5 wt % to obtain a raw material composition having the following molar composition.

(34) SiO.sub.2/Al.sub.2O.sub.3 ratio=18.2

(35) TEA/SiO.sub.2 ratio=0.12

(36) K/SiO.sub.2 ratio=0.12

(37) H.sub.2O/SiO.sub.2 ratio=12.0

(38) OH/SiO.sub.2 ratio=0.24

(39) Seed crystal=1.5 wt %

(40) The raw material composition filled in a closed sealed container was reacted at 150° C. for 48 hours while rotating the container at 55 rpm to obtain a crystallized product. The resulting crystallized product was subjected to solid-liquid separation, washed with pure water, dried in an atmosphere at 110° C., and collected. The crystallized product was a zeolite made of a single phase of β-zeolite having an FWHM of Peak.sub.(302) of 0.20.

(41) The main XRD peaks of the resulting crystallized product are shown in the following table, and the XRD pattern is shown in FIG. 2.

(42) TABLE-US-00005 TABLE 5 2θ Relative intensity* 21.32 14 22.34 100 25.20 8 26.80 14 29.40 16 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.34°.

(43) The resulting crystallized product was calcined in an atmosphere at 600° C. for 2 hours to obtain a β-zeolite in the present Example. The β-zeolite in the present Example was a zeolite made of a single phase of β-zeolite having an FWHM of Peak.sub.(302) of 0.27 and an FWHM change ratio of 1.35. The SiO.sub.2/Al.sub.2O.sub.3 ratio was 17.6, the average crystal particle size was 0.37 μm, and both the SiO.sub.2/Al.sub.2O.sub.3 ratio and the average crystal particle size were the values similar to those of the crystallized product before calcination. The main XRD peaks of the resulting β-zeolite are shown in the following table, and the XRD pattern is shown in FIG. 3.

(44) TABLE-US-00006 TABLE 6 2θ Relative intensity* 13.42° 8 21.32° 14 22.38° 100 25.26° 13 27.02° 16 28.58° 10 29.52° 16 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.38°.

Example 2

(45) The crystallization, solid-liquid separation, washing and drying were performed in the same manner as in Example 1 to obtain a crystallized product, except that composition of the raw material composition was set to the following.

(46) SiO.sub.2/Al.sub.2O.sub.3 ratio=18.2

(47) TEAOH/SiO.sub.2 ratio=0.09

(48) K/SiO.sub.2 ratio=0.15

(49) H.sub.2O/SiO.sub.2 ratio=12.0

(50) OH/SiO.sub.2 ratio=0.24

(51) Seed crystal=1.5 wt %

(52) The resulting crystallized product was a zeolite made of a single phase of β-zeolite having an FWHM of Peak.sub.(302) of 0.18. The main XRD peaks of the crystallized product are shown in the following table.

(53) TABLE-US-00007 TABLE 7 2θ Relative intensity* 21.32° 14 22.36° 100 25.22° 8 26.82° 15 29.42° 17 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.36°.

(54) The crystallized product was calcined in the same manner as in Example 1 to obtain a β-zeolite in the present example. The β-zeolite in the present Example was a zeolite made of a single phase of β-zeolite having an FWHM of Peak.sub.(302) of 0.28 and an FWHM change ratio of 1.56. The SiO.sub.2/Al.sub.2O.sub.3 ratio was 17.4, the average crystal particle size was 0.38 μm, and both were the values similar to those of the crystallized product before calcination.

(55) The main XRD peaks of the β-zeolite in the present Example are shown in the following table.

(56) TABLE-US-00008 TABLE 8 2θ Relative intensity* 13.44° 7 21.30° 13 22.36° 100 25.26° 14 27.02° 16 28.62° 9 29.52° 18 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.38°.

Example 3

(57) The crystallization, solid-liquid separation, washing and drying were performed in the same manner as in Example 1 to obtain a crystallized product, except that composition of the raw material composition was set to the following.

(58) SiO.sub.2/Al.sub.2O.sub.3=18.2

(59) TEAOH/SiO.sub.2=0.12

(60) K/SiO.sub.2=0.20

(61) H.sub.2O/SiO.sub.2=12.0

(62) OH/SiO.sub.2=0.32

(63) Seed crystal=1.5 wt %

(64) The resulting crystallized product had a β-type structure content of 93%, and contained 7% GIS-type zeolite. The FWHM of Peak.sub.(302) of the β-zeolite contained in the zeolite was 0.18.

(65) The main XRD peaks of the crystallized product are shown in the following table.

(66) TABLE-US-00009 TABLE 9 2θ Relative intensity* 21.32° 12 22.36° 100 25.20° 8 26.80° 15 29.40° 16 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.36°.

(67) The resulting crystallized product was calcined in the same manner as in Example 1 to obtain a β-zeolite in the present Example. The β-zeolite in the present Example was a zeolite made of a single phase of β-zeolite having an FWHM of Peak.sub.(302) of 0.28 and an FWHM change ratio of 1.56. The SiO.sub.2/Al.sub.2O.sub.3 ratio was 15.6, the average crystal particle size was 0.52 μm, and both were the values similar to those of the β-zeolite before calcination.

(68) From the XRD measurement results of the β-zeolite in the present Example, it was confirmed that a very small amount of GIS-type zeolite contained in the β-zeolite after crystallization disappeared by calcination.

(69) The main XRD peaks of the β-zeolite in the present Example are shown in the following table, the XRD pattern is shown in FIG. 4, and the SEM observation view is shown in FIG. 5.

(70) TABLE-US-00010 TABLE 10 2θ Relative intensity* 13.44° 7 21.34° 13 22.40° 100 25.30° 13 27.04° 19 28.64° 9 29.54° 17 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.40°.

Example 4

(71) The crystallization, solid-liquid separation, washing and drying were performed in the same manner as in Example 1 to obtain a crystallized product, except that composition of the raw material composition was set to the following.

(72) SiO.sub.2/Al.sub.2O.sub.3 ratio=18.2

(73) TEAOH/SiO.sub.2 ratio=0.10

(74) K/SiO.sub.2 ratio=0.16

(75) H.sub.2O/SiO.sub.2 ratio=12.0

(76) OH/SiO.sub.2 ratio=0.26

(77) Seed crystal=1.5 wt %

(78) The resulting crystallized product had a β-type structure content of 95%, and contained 5% GIS-type zeolite. The FWHM of Peak.sub.(302) of the β-zeolite contained in the zeolite was 0.19.

(79) The main XRD peaks of the crystallized product are shown in the following table.

(80) TABLE-US-00011 TABLE 11 2θ Relative intensity* 21.34° 12 22.34° 100 25.22° 8 26.80° 15 29.40° 17 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.34°.

(81) The crystallized product was calcined in the same manner as in Example 1 to obtain a β-zeolite in the present Example. The β-zeolite in the present Example was a zeolite made of a single phase of β-zeolite having an FWHM of Peak.sub.(302) of 0.28 and an FWHM change ratio of 1.47. The SiO.sub.2/Al.sub.2O.sub.3 ratio was 16.8, the average crystal particle size was 0.44 μm, and both were the values similar to those of the zeolite before calcination.

(82) The main XRD peaks of the β-zeolite in the present Example are shown in the following table.

(83) TABLE-US-00012 TABLE 12 2 θ Relative intensity* 13.42° 7 21.32° 14 22.38° 100 25.28° 13 27.02° 16 28.62° 9 29.52° 16 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.38°.

Example 5

(84) The crystallization, solid-liquid separation, washing and drying were performed in the same manner as in Example 1 to obtain a crystallized product, except that composition of the raw material composition having the same composition as in Example 4 was used and the crystallization temperature was set to 140° C.

(85) The resulting crystallized product was a zeolite made of a single phase of β-zeolite.

(86) The crystallized product was calcined in the same manner as in Example 1 to obtain a β-zeolite in the present Example. The β-zeolite in the present Example was a zeolite made of a single phase of β-zeolite having an FWHM of Peak.sub.(302) of 0.38. The SiO.sub.2/Al.sub.2O.sub.3 ratio was 17.5, the average crystal particle size was 0.40 μm, and both were the values similar to those of the crystallized product before calcination.

(87) The main XRD peaks of the β-zeolite in the present Example are shown in the following table.

(88) TABLE-US-00013 TABLE 13 2θ Relative intensity* 13.44° 8 21.32° 12 22.40° 100 25.30° 13 27.06° 17 28.62° 9 29.56° 15 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.40°.

Example 6

(89) The crystallization, solid-liquid separation, washing and drying were performed in the same manner as in Example 1 to obtain a crystallized product, except that composition of the raw material composition was set to the following, and the crystallization temperature was set to 170° C.

(90) SiO.sub.2/Al.sub.2O.sub.3 ratio=18.2

(91) TEAOH/SiO.sub.2 ratio=0.09

(92) K/SiO.sub.2 ratio=0.12

(93) H.sub.2O/SiO.sub.2 ratio=12.0

(94) OH/SiO.sub.2 ratio=0.21

(95) Seed crystal=1.5 wt %

(96) The resulting crystallized product was a zeolite made of a single phase of β-zeolite.

(97) The crystallized product was calcined in the same manner as in Example 1 to obtain a β-zeolite in the present Example. The β-zeolite in the present Example was a zeolite made of a single phase of β-zeolite having an FWHM of Peak.sub.(302) of 0.40. The SiO.sub.2/Al.sub.2O.sub.3 ratio was 18.0, the average crystal particle size was 0.38 μm, and both were the values similar to those of the crystallized product before calcination.

(98) The main XRD peaks of the β-zeolite in the present Example are shown in the following table.

(99) TABLE-US-00014 TABLE 14 2θ Relative intensity* 13.44° 7 21.32° 12 22.38° 100 25.28° 12 27.06° 14 28.66° 11 29.54° 13 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.38°.

Example 7

(100) The crystallization, solid-liquid separation, washing and drying were performed in the same manner as in Example 1 to obtain a crystallized product, except that an amorphous aluminosilicate having an SiO.sub.2/Al.sub.2O.sub.3 ratio of 14.8 was used and composition of the raw material composition was set to the following.

(101) SiO.sub.2/Al.sub.2O.sub.3 ratio=14.8

(102) TEAOH/SiO.sub.2 ratio=0.12

(103) K/SiO.sub.2 ratio=0.14

(104) H.sub.2O/SiO.sub.2 ratio=12.0

(105) OH/SiO.sub.2 ratio=0.26

(106) Seed crystal=1.5 wt %

(107) The resulting crystallized product had a β-zeolite content of 86%, and contained 14% GIS-type zeolite. The FWHM of Peak.sub.(302) of the β-zeolite contained in the crystallized product was 0.19.

(108) The main XRD peaks of the crystallized product are shown in the following table.

(109) TABLE-US-00015 TABLE 15 2θ Relative intensity* 21.30° 14 22.36° 100 25.22° 7 26.78° 13 29.42° 15 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.36°.

(110) The crystallized product was calcined in the same manner as in Example 1 to obtain a β-zeolite in the present Example. The β-zeolite in the present Example had a β-type structure content of 89% and contained an 11% GIS-type zeolite. The β-zeolite in the crystallized product had an FWHM of Peak.sub.(302) of 0.26 and an FWHM change ratio of 1.37. The SiO.sub.2/Al.sub.2O.sub.3 ratio was 14.2 and the average crystal particle size was 0.39 μm, which were the values similar to those of the crystallized product before calcination, respectively.

(111) From the present Example, it was confirmed that 14% or more of the by-product zeolite decreased by calcination and remained after calcination.

(112) The main XRD peaks of the β-zeolite in the present Example are shown in the following table.

(113) TABLE-US-00016 TABLE 16 2θ Relative intensity* 13.40° 7 21.32° 12 22.38° 100 25.28° 12 27.00° 13 28.62° 8 29.52° 16 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.38°.

Example 8

(114) The crystallization, solid-liquid separation, washing and drying were performed in the same manner as in Example 1 to obtain a crystallized product, except that an amorphous aluminosilicate having an SiO.sub.2/Al.sub.2O.sub.3 ratio of 14.8 was used and composition of the raw material composition was set to the following.

(115) SiO.sub.2/Al.sub.2O.sub.3 ratio=14.8

(116) TEAOH/SiO.sub.2 ratio=0.09

(117) K/SiO.sub.2 ratio=0.16

(118) H.sub.2O/SiO.sub.2 ratio=12.0

(119) OH/SiO.sub.2 ratio=0.25

(120) Seed crystal=1.5 wt %

(121) The resulting crystallized product had a β-type structure content of 84%, and contained 16% GIS-type zeolite. The FWHM of Peak.sub.(302) of the β-zeolite contained in the crystallized product was 0.18.

(122) The main XRD peaks of the crystallized product are shown in the following table.

(123) TABLE-US-00017 TABLE 17 2θ Relative intensity* 21.32° 13 22.34° 100 25.24° 7 26.82° 13 29.40° 15 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.34°.

(124) The crystallized product was calcined in the same manner as in Example 1 to obtain a β-zeolite in the present Example. The β-zeolite in the present Example had a β-type structure content of 92% and contained an 8% GIS-type zeolite. The β-zeolite in the present Example had an FWHM of Peak.sub.(302) of 0.27 and an FWHM change ratio of 1.50. The SiO.sub.2/Al.sub.2O.sub.3 ratio was 14.2 and the average crystal particle size was 0.45 μm, which were the values similar to those of the zeolite before calcination, respectively.

(125) From the present Example, it was confirmed that 16% or more of the by-product zeolite decreased by calcination but remained after calcination.

(126) The main XRD peaks of the β-zeolite in the present Example are shown in the following table.

(127) TABLE-US-00018 TABLE 18 2θ Relative intensity* 13.42° 8 21.34° 13 22.38° 100 25.28° 13 27.02° 15 28.62° 9 29.52° 15 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.38°.

Example 9

(128) After mixing a 35 wt % TEAOH aqueous solution, a 48 wt % potassium hydroxide aqueous solution, a 48 wt % sodium hydroxide aqueous solution, pure water and an amorphous aluminosilicate (SiO.sub.2/Al.sub.2O.sub.3 ratio=18.2), a β-zeolite (product name: HSZ930NHA, manufactured by Tosoh Corporation) was added as seed crystal by 1.5 wt % to the mixture to obtain a raw material composition having the following molar composition.

(129) SiO.sub.2/Al.sub.2O.sub.3=18.2

(130) TEA/SiO.sub.2=0.12

(131) K/SiO.sub.2=0.12

(132) Na/SiO.sub.2=0.04

(133) H.sub.2O/SiO.sub.2=12.0

(134) OH/SiO.sub.2=0.28

(135) Seed crystal=1.5 wt %

(136) The raw material composition was treated in the same manner as in Example 1, so that a crystallized product was obtained. The crystallized product was a zeolite made of a single phase of β-zeolite, having an FWHM of Peak.sub.(302) of 0.22. The main XRD peaks of the resulting crystallized product are shown in the following table.

(137) TABLE-US-00019 TABLE 19 2θ Relative intensity* 21.32 14 22.34 100 25.24 7 26.80 14 29.40 16 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.34°.

(138) The resulting crystallized product was calcined in the same manner as in Example 1 to make a β-zeolite in the present Example. The β-zeolite in the present Example was a zeolite made of a single phase of β-zeolite and had an FWHM of Peak.sub.(302) of 0.29 and an FWHM change ratio of 1.32. The SiO.sub.2/Al.sub.2O.sub.3 ratio was 17.2 and the average crystal particle size was 0.35 μm, which were the values similar to those of the crystallized product before calcination, respectively. The main XRD peaks of the resulting β-zeolite are shown in the following table.

(139) TABLE-US-00020 TABLE 20 2θ Relative intensity* 13.42° 8 21.32° 13 22.38° 100 25.26° 13 27.02° 16 28.58° 10 29.50° 16 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.38°.

(140) The IR spectrum of the β-zeolite had P1 and P2 at 3733 cm.sup.−1 and 3591 cm.sup.−1, respectively. Also, P2/P1 was 0.28.

Example 10

(141) After mixing a 35 wt % TEAOH aqueous solution, a 48 wt % potassium hydroxide aqueous solution, pure water and an amorphous aluminosilicate (SiO.sub.2/Al.sub.2O.sub.3 ratio=17.4), a β-zeolite (product name: HSZ930NHA, manufactured by Tosoh Corporation) was added as seed crystal by 1.5 wt % to the mixture to obtain a raw material composition having the following molar composition.

(142) SiO.sub.2/Al.sub.2O.sub.3 ratio=17.4

(143) TEA/SiO.sub.2 ratio=0.09

(144) K/SiO.sub.2 ratio=0.16

(145) H.sub.2O/SiO.sub.2 ratio=11.0

(146) OH/SiO.sub.2 ratio=0.25

(147) Seed crystal=1.5 wt %

(148) The raw material composition filled in a 4-L autoclave was agitated at 245 rpm at 150° C. for 44 hours to cause a reaction of the raw material composition, so that a crystallized product was obtained. The resulting crystallized product was subjected to solid-liquid separation, washed with pure water, and then dried in an atmosphere at 110° C. to be collected. The crystallized product had a β-type structure content of 95% and contained 5% GIS-type zeolite. The FWHM of Peak.sub.(302) of the β-zeolite in the crystallized product was 0.19.

(149) The main XRD peaks of the resulting crystallized product are shown in the following table.

(150) TABLE-US-00021 TABLE 21 2θ Relative intensity* 21.34 12 22.38 100 25.26 8 26.82 14 29.44 15 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.38°.

(151) The resulting crystallized product was calcined in an atmosphere at 600° C. for 2 hours to obtain a β-zeolite in the present Example. The β-zeolite in the present Example was a zeolite made of a single phase of β-zeolite having an FWHM of Peak.sub.(302) of 0.29 and an FWHM change ratio of 1.53. The SiO.sub.2/Al.sub.2O.sub.3 ratio was 16.4, the average crystal particle size was 0.51 μm, and both were the values similar to those of the crystallized product before calcination. The SEM observation view is shown in FIG. 6. The crystal particles are mainly made of primary crystal particles and included a small amount of aggregated crystal particles.

(152) Using a field emission type electron microscope (apparatus name: S-4500, manufactured by Hitachi, Ltd.), crystals constituting an aggregated crystal particle was observed. The results are shown in FIG. 7. The aggregated crystal particle is composed of crystals in a double quadrangular frustum oriented in the a-axis direction and the b-axis direction, and the crystal has an aspect ratio of 0.7.

(153) The main XRD peaks of the resulting β-zeolite are shown in the following table.

(154) TABLE-US-00022 TABLE 22 2θ Relative intensity* 13.44° 12 21.40° 11 22.46° 100 25.34° 12 27.04° 16 28.58° 6 29.58° 12 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.46°.

(155) The IR spectrum of the β-zeolite had P1 and P2 at 3731 cm.sup.−1 and 3592 cm.sup.−1, respectively. Also, P2/P1 was 0.33.

(156) From these Examples, it was confirmed that a β-zeolite having a Peak.sub.(302) of 0.15 or more and 0.50 or less and an SiO.sub.2/Al.sub.2O.sub.3 ratio of less than 20 can be obtained by crystallizing a raw material composition containing TEA.sup.+ as an organic structure directing agent, having a K/SiO.sub.2 ratio of more than 0.04. Further, it was confirmed that the resulting β-zeolite has an average crystal particles size of more than 0.30 μm and is mainly composed of primary crystal particles with less physical agglomeration. The fluorine content in the β-zeolite in the present Example was equal to or less than the detection limit. Since any of the raw material compositions in the production method in the present Example contain no fluorine compound, it is obvious that the resulting β-zeolite has a fluorine content of 100 ppm by weight or less or has no fluorine content.

Comparative Example 1

(157) After mixing a 35 wt % TEAOH aqueous solution, a 48 wt % sodium hydroxide aqueous solution, pure water and amorphous aluminosilicate (SiO.sub.2/Al.sub.2O.sub.3 ratio=18.2), a commercially available β-zeolite (product name: HSZ930NHA, manufactured by Tosoh Corporation) was further added thereto by 1.5 wt % relative to the silica content in the slurry to obtain a raw material composition having the following molar composition.

(158) SiO.sub.2/Al.sub.2O.sub.3 ratio=18.2

(159) TEAOH/SiO.sub.2 ratio=0.10

(160) Na/SiO.sub.2 ratio=0.14

(161) H.sub.2O/SiO.sub.2 ratio=12.0

(162) OH/SiO.sub.2 ratio=0.24

(163) Seed crystal=1.5 wt %

(164) The raw material composition was crystallized in the same manner as in Example 1 to obtain a crystallized product. The resulting crystallized product was a zeolite made of a single phase of β-zeolite having an FWHM of 0.53.

(165) The zeolite was calcined in an atmosphere at 600° C. for 2 hours to obtain a β-zeolite in the present Comparative Example. The β-zeolite in the present Comparative Example was a zeolite made of a single phase of β-zeolite having an FWHM of the XRD peak corresponding to Peak.sub.(302) of 0.59. The SiO.sub.2/Al.sub.2O.sub.3 ratio was 17.7 and the average crystal particle size was less than 0.15 μm, both being comparative to the values before calcination.

(166) The main XRD peaks of the zeolite in the present Comparative Example are shown in the following table.

(167) TABLE-US-00023 TABLE 23 2θ Relative intensity* 21.40° 7 22.48° 100 25.36° 18 27.02° 16 29.60° 12 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.48°

(168) The IR spectrum of the β-zeolite had P1 and P2 at 3735 cm.sup.−1 and 3595 cm.sup.−1, respectively, with P2/P1 of 0.07.

(169) From these results, it was confirmed that the β-zeolite in the present Comparative Example has a larger FWHM and lower crystallinity than the β-zeolite in Examples, being different in the XRD pattern from the β-zeolite in Examples.

(170) From the present Comparative Example, it was confirmed that the zeolite obtained from a raw material composition containing potassium is a β-zeolite having large crystal particles, while the zeolite obtained from a raw material composition containing no potassium is a β-zeolite having small crystal grains.

Comparative Example 2

(171) A β-zeolite was synthesized according to a method described in Example 4 in Patent literature 3.

(172) In other words, crystallization, solid-liquid separation, washing and drying were performed in the same manner as in Example 1 to obtain a crystallized product except that the composition of the reaction composition was set to
SiO.sub.2:0.034Al.sub.2O.sub.3:0.05KOH:0.14TEAOH:9.9H.sub.2O,
and the crystallization time was set to 88 hours.

(173) The resulting crystallized product was a zeolite made of a single phase of β-zeolite.

(174) The zeolite was calcined in the same manner as in Comparative Example 1 to obtain a zeolite in the present Comparative Example. The zeolite in the present Comparative Example was a zeolite made of a single phase of β-zeolite having an FWHM of the XRD peak corresponding to Peak.sub.(302) of 0.24. The SiO.sub.2/Al.sub.2O.sub.3 ratio was 29.1 and the average crystal particle size was 0.43 μm, both being comparative to the values of the zeolite before calcination.

(175) The XRD pattern of the zeolite in the present Comparative Example is shown in FIG. 8 and the main XRD peaks are shown in the following table, respectively.

(176) TABLE-US-00024 TABLE 24 2θ Relative intensity* 21.46° 11 22.52° 100 25.40° 13 27.08° 17 29.66° 13 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.52°.

(177) From these results, it was confirmed that the β-zeolite in the present Comparative Example is different in the XRD pattern from the β-zeolite in the present embodiment, though having crystallinity comparative to that of the β-zeolite in the present embodiment, due to having an SiO.sub.2/Al.sub.2O.sub.3 ratio of 20 or more.

Comparative Example 3

(178) A β-zeolite was synthesized from a raw material composition containing no SDA according to a method described in Example 8 in Patent literature 6.

(179) In other words, after dissolving NaAlO.sub.2 and NaOH in water, a fumed silica was added thereto. Subsequently, the mixture was agitated for 15 minutes to obtain an aluminosilicate gel having the following composition (raw material composition).
40.28 SiO.sub.2:1.00 Al.sub.2O.sub.3:13.06 Na.sub.2O:1133.32 H.sub.2O

(180) To the aluminosilicate gel, a β-zeolite (product name: HSZ920HOA, manufactured by Tosoh Corporation) was added by 10.0 wt % and mixed.

(181) The resulting raw material composition was transferred to an autoclave and reacted at 140° C. for 19 hours to obtain a crystallized product. The crystallized product was solid-liquid separated, washed with pure water, then dried in an atmosphere at 110° C. and collected.

(182) The crystallized product was a zeolite made of a single phase of β-zeolite.

(183) The resulting zeolite was calcined in the same manner as in Comparative Example 1 to make a zeolite in the present Comparative Example. The zeolite in the present Comparative Example was a zeolite made of a single phase of β-zeolite having an FWHM of the XRD peak corresponding to Peak.sub.(302) of 0.28. The SiO.sub.2/Al.sub.2O.sub.3 ratio was 10.0 and the average crystal particle size was 0.34 μm, both being comparative to the values of the zeolite before calcination, respectively. It was confirmed that the crystal particles of the β-zeolite in the present Comparative Example contain primary crystal particles composed of crystals in an approximately octahedron shape.

(184) The crystals composing the crystal particles of the β-zeolite in the present Comparative Example were observed. The results are shown in FIG. 9. The crystal particle is composed of a crystal in an approximately octahedron shape oriented in the a-axis direction and the c-axis direction, with a double quadrangular frustum bottom to make the ridges and vertexes. The aspect ratio of the crystal was 1.5. It was therefore confirmed that the zeolite obtained by crystallizing a raw material composition containing no SDA is different in the shape of crystal and the orientation of crystal from the β-zeolite in the present embodiment.

(185) Furthermore, the β-zeolite in the present Comparative Example has XRD peaks at 2θ=21.26°, 22.32° and 26.98°, while having no XRD peaks at 2θ=21.28° to 21.40°, 22.33° to 33.46°, and 27.00° to 27.12°. It was therefore confirmed that the β-zeolite in the present Comparative Example has an XRD pattern different from that of the β-zeolite in the present embodiment.

(186) The IR spectrum of the β-zeolite had P1 and P2 at 3735 cm.sup.−1 and 3595 cm.sup.−1, respectively. Also, P2/P1 was 1.00.

Comparative Example 4

(187) A β-zeolite having an SiO.sub.2/Al.sub.2O.sub.3 ratio of less than 20 was produced according to a method described in Example 1 in Patent Literature 1.

(188) In other words, a sodium aluminate solution (18.89 wt % Al.sub.2O.sub.3, 19.61 wt % Na.sub.2O, 61.50 wt % H.sub.2O), sodium hydroxide, TEAOH, pure water and fumed silica (AEROSIL 200) were sufficiently agitated in an autoclave reactor to obtain a raw material composition having the following composition.
23.1 SiO.sub.2:1.00 Al.sub.2O.sub.3:1.94 Na.sub.2O:1.62 (TEA).sub.2O:767 H.sub.2O

(189) To the resulting raw material composition, a β-zeolite was added by 7.55 wt % relative to the silica content in the composition and mixed.

(190) The resulting raw material composition was reacted at 150° C. for 6 days to obtain a crystallized product. The crystallized product was subjected to solid-liquid separation, washed with deionized water, then dried in an atmosphere at 110° C. and collected.

(191) The crystallized product was a zeolite made of a single phase of β-zeolite. The FWHM of the XRD peak corresponding to Peak.sub.(302) of the β-zeolite was 0.57. The main XRD peaks of the β-zeolite are shown in the following table.

(192) TABLE-US-00025 TABLE 25 2 θ Relative intensity* 21.52° 8 22.49° 100 25.40° 7 26.96° 16 29.60° 12 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.49°.

(193) The zeolite was calcined in the same manner as in Comparative Example 1 to obtain a zeolite in the present Comparative Example. The zeolite in the present Comparative Example was a zeolite made of a single phase of β-zeolite having an FWHM of the XRD peak corresponding to Peak.sub.(302) of 0.59 and an SiO.sub.2/Al.sub.2O.sub.3 ratio of 18.2.

(194) The main XRD peaks of the β-zeolite in the present Comparative Example are shown in the following table, the XRD pattern is shown in FIG. 10, and the SEM observation view is shown in FIG. 11.

(195) TABLE-US-00026 TABLE 26 2 θ Relative intensity* 13.48° 9 21.36° 9 22.48° 100 25.26° 10 27.04° 17 28.66° 10 29.64° 11 *Relative intensity is an intensity relative to peak intensity at 2θ = 22.48°.

(196) The β-zeolite in the present Comparative Example, which was made by crystallizing a raw material composition having a K/SiO.sub.2 ratio of 0.04, or further a raw material composition containing no potassium source, had an FWHM of the peak corresponding to Peak.sub.(302) larger than that of the β-zeolite in the present embodiment. It was therefore confirmed that the production method using a raw material composition containing no potassium source and the β-zeolite obtained thereby were different from those in the present embodiment. In addition thereto, the β-zeolite in the present Comparative Example had Peak.sub.(302) at a larger 2θ than the β-zeolite in the present Example.

(197) In addition thereto, no primary crystal particle having a distinct shape was found in SEM observation with a magnification of 15000 times in FIG. 11, and therefore it was confirmed that no primary crystal particle having a size of more than 0.15 μm is present. While it was confirmed that a β-zeolite having a large average crystal particle size can be obtained by the production method in Examples even with an SiO.sub.2/Al.sub.2O.sub.3 ratio of less than 20, it was confirmed that only a β-zeolite having a small average crystal particle size can be obtained from a raw material composition having a K/SiO.sub.2 ratio of 0.04 or less, or containing no potassium source.

Measurement Example 1

(198) (Evaluation of Heat Resistance)

(199) Each of the zeolite samples obtained in Example 1, Example 2 and Comparative Example 1 was molded and ground to make aggregates having an aggregate size of 12 to 20 mesh. After filling 3 mL of the resulting aggregates in a normal pressure fixed bed flow type reaction tube, air containing 10 vol % of water was circulated therein under the following conditions to perform a hydrothermal aging treatment.

(200) Air circulation rate: 300 mL/min

(201) Treatment temperature: 700° C.

(202) Treatment time: 20 hours

(203) The zeolite samples before and after the hydrothermal aging treatment were subjected to XRD measurement in the same manner as in the identification of the crystal phase, so that the FWHM of P.sub.(302) of the resulting XRD patterns was determined. The results are shown in the following table.

(204) TABLE-US-00027 TABLE 27 FWHM (°) Before After hydrothermal SiO.sub.2/Al.sub.2O.sub.3 hydrothermal aging treatment ratio aging treatment (FWHM.sub.aged) Example 1 17.4 0.27 0.31 Example 2 17.6 0.28 0.30 Comparative 17.7 0.59 0.60 Example 1

(205) Although all the β-zeolites in Examples 1 and 2 and Comparative Example 1 are β-zeolites having a comparable SiO.sub.2/Al.sub.2O.sub.3 ratio of less than 20, the FWHM of Peak.sub.(302) of the β-zeolites in Examples 1 and 2 before the hydrothermal aging treatment was 0.30 or less, i.e., smaller than that of the β-zeolite in Comparative Example 1. From the results, it was confirmed that the β-zeolite in the present Examples has high crystallinity in comparison with a conventional β-zeolite having an SiO.sub.2/Al.sub.2O.sub.3 ratio of less than 20.

(206) From the above table, it was also confirmed that FWHM of all the β-zeolites increases by the hydrothermal aging treatment. In addition thereto, FWHM.sub.aged was 0.60 in Comparative Example 1, while 0.35 or less in any of Examples. It was thereby confirmed that the β-zeolite in Examples can retain high crystallinity even after exposure to high temperature and high humidity, having a higher heat resistance than a conventional β-zeolite having an SiO.sub.2/Al.sub.2O.sub.3 ratio of less than 20.

Measurement Example 2

(207) (Containing Iron)

(208) From the zeolite obtained in Example 1 and Comparative Examples 1 and 2, iron-containing β-zeolites were obtained. In other words, an aqueous solution of iron nitrate was prepared by dissolving 2.24 g of iron nitrate nonahydrate in 3.1 g of pure water. The aqueous solution of iron nitrate was dropped to 10.0 g of a calcined zeolite, and then mixed in a mortar for 10 minutes. After mixing, the β-zeolite was dried at 110° C. overnight, and then calcined in air at 500° C. for 1 hour to obtain an iron-containing β-zeolite.

(209) (Hydrothermal Aging Treatment)

(210) The iron-containing β-zeolite was molded and ground to make aggregates having an aggregate size of 12 to 20 mesh. After 3 mL of aggregates of iron-containing β-zeolite were filled in a normal pressure fixed bed flow type reaction tube, air containing 10 vol % water was circulated to perform a hydrothermal aging treatment under the following conditions.

(211) Air circulation rate: 300 mL/min

(212) Treatment temperature: 700° C.

(213) Treatment time: 20 hours

(214) (Method for Measuring Nitrogen Oxide Reduction Ratio (%))

(215) The samples before and after the hydrothermal aging treatment were molded and ground to make aggregates having an aggregate size of 12 to 20 mesh. After filling 1.5 mL of the sample in an aggregate form in a normal pressure fixed bed flow type reaction tube, a nitrogen oxide-containing gas held at the following measurement temperature was circulated to measure the concentration of nitrogen oxides at the inlet and outlet of the normal pressure fixed bed flow type reaction tube. The circulation conditions of the nitrogen oxide-containing gas were as follows.

(216) Composition of nitrogen oxide-containing gas:

(217) NO: 200 ppm

(218) NH.sub.3: 200 ppm

(219) O.sub.2: 10 vol %

(220) H.sub.2O: 3 vol %

(221) N.sub.2: balance

(222) Nitrogen oxide-containing gas circulation rate: 1.5 L/min

(223) Space velocity: 60000 hr.sup.−1

(224) Measurement temperature: 200° C.

(225) From the nitrogen oxide concentration obtained, the nitrogen oxide reduction ratio was determined by the following equation.
Nitrogen oxide reduction ratio (%)={([NOx]in−[NOx]out)/[NOx]in}×100

(226) [NOx]in is the nitrogen oxide concentration of the nitrogen oxide-containing gas at the inlet of the normal pressure fixed bed flow reactor, and [NOx]out is the nitrogen oxide concentration of the nitrogen oxide-containing gas at the outlet of the normal pressure fixed bed flow reactor.

(227) The nitrogen oxide reduction ratio of the iron-containing β-zeolite before hydrothermal aging treatment (hereinafter also referred to as “fresh sample”), and the nitrogen oxide reduction ratio of the iron-containing β-zeolite after hydrothermal aging treatment (hereinafter also referred to as “20-h aging sample”) are shown in the following table and FIG. 12.

(228) TABLE-US-00028 TABLE 28 Nitrogen oxide reduction ratio (%) Iron 20-h SiO.sub.2/Al.sub.2O.sub.3 content Fresh Aging ratio (wt %) sample sample Example 1 17.4 3.0 83 83 Comparative 27.7 3.0 81 59 Example 2

(229) The iron-containing β-zeolite in Comparative Example 2 is an iron-containing β-zeolite having a relatively small decrease in nitrogen oxide reduction ratio with an SiO.sub.2/Al.sub.2O.sub.3 ratio of 25 or more. In comparison with the iron-containing β-zeolite, the fresh sample of the iron-containing β-zeolite in the present Examples exhibited a comparative nitrogen oxide reduction ratio. In addition thereto, having an effect that decrease in the nitrogen oxide reduction ratio is smaller than that of the β-zeolite in Comparative Example 2 even after exposure to a high temperature water-containing atmosphere for a long time was confirmed. It was therefore confirmed that the β-zeolite in the present Examples has higher heat resistance and a smaller decrease in nitrogen oxide reduction ratio in a low temperature range in comparison with the β-zeolite having an SiO.sub.2/Al.sub.2O.sub.3 ratio of 20 or more.

(230) Next, the ratio of the nitrogen oxide reduction ratio of the 20-h aging sample to the nitrogen oxide reduction ratio of the fresh sample is shown in the following table.

(231) TABLE-US-00029 TABLE 29 Iron Change ratio of SiO.sub.2/Al.sub.2O.sub.3 content nitrogen oxide ratio (wt %) reduction ratio (%) Example 1 17.4 3.0 100% Comparative 17.7 3.0  74% Example 1

(232) The iron-containing β-zeolites in Comparative Example 1 and Example 1 have an SiO.sub.2/Al.sub.2O.sub.3 ratio of less than 20. Through a 20-hour hydrothermal aging treatment, while the nitrogen oxide reduction ratio of the iron-containing β-zeolite in Comparative Example 1 decreased by 25% or more, decrease in the nitrogen oxide reduction ratio of the iron-containing β-zeolite in Example 1 was undetectable in the range of measurement accuracy. It can be therefore confirmed that the β-zeolite in the present embodiment has higher heat resistance and smaller decrease in the nitrogen oxide reduction ratio in a low temperature range even after exposure to a high temperature and high humidity atmosphere, in comparison with a conventional β-zeolite having an SiO.sub.2/Al.sub.2O.sub.3 ratio of less than 20.

(233) It has been therefore confirmed that the iron-containing β-zeolite in the present Examples can be used as a catalyst having a long life when used as a catalyst for reducing nitrogen oxides, in addition to an effect having an excellent nitrogen oxide reduction characteristics.

INDUSTRIAL APPLICABILITY

(234) The β-zeolite in the present disclosure can be used as a catalyst, particularly as a catalyst for reducing nitrogen oxides and a catalyst for reducing nitrogen oxides in a urea SCR. Furthermore, the β-zeolite in the present disclosure can be used as a catalyst base and an adsorbent base, and the production method thereof can be applied as an industrial method for producing a β-zeolite.

(235) The entire content of the specification, claims, drawings and abstract of Japanese Patent Application No. 2017-239174 filed on Dec. 14, 2017 is incorporated herein by reference and incorporated as disclosure of the specification of the present invention.