CN118159361A - Catalyst support, catalyst, and method for producing the same - Google Patents
Catalyst support, catalyst, and method for producing the same Download PDFInfo
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- CN118159361A CN118159361A CN202280071768.0A CN202280071768A CN118159361A CN 118159361 A CN118159361 A CN 118159361A CN 202280071768 A CN202280071768 A CN 202280071768A CN 118159361 A CN118159361 A CN 118159361A
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- catalyst
- metal oxide
- porous silica
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- 239000003054 catalyst Substances 0.000 title claims abstract description 205
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 34
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 143
- 239000002245 particle Substances 0.000 claims abstract description 110
- 229910044991 metal oxide Inorganic materials 0.000 claims abstract description 94
- 150000004706 metal oxides Chemical class 0.000 claims abstract description 94
- 238000000034 method Methods 0.000 claims abstract description 26
- 230000000737 periodic effect Effects 0.000 claims abstract description 22
- 239000011148 porous material Substances 0.000 claims abstract description 21
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 11
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical group [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 65
- 239000002082 metal nanoparticle Substances 0.000 claims description 46
- 239000012702 metal oxide precursor Substances 0.000 claims description 30
- 238000002441 X-ray diffraction Methods 0.000 claims description 19
- 239000000843 powder Substances 0.000 claims description 16
- 239000000203 mixture Substances 0.000 claims description 14
- 238000010304 firing Methods 0.000 claims description 13
- 238000002156 mixing Methods 0.000 claims description 13
- -1 platinum group metal compound Chemical class 0.000 claims description 10
- 239000004745 nonwoven fabric Substances 0.000 claims description 7
- 238000000465 moulding Methods 0.000 claims description 5
- 239000000377 silicon dioxide Substances 0.000 abstract description 29
- 239000000047 product Substances 0.000 description 34
- 230000000052 comparative effect Effects 0.000 description 29
- 238000010438 heat treatment Methods 0.000 description 19
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 18
- 239000005977 Ethylene Substances 0.000 description 18
- 239000011734 sodium Substances 0.000 description 16
- 230000000694 effects Effects 0.000 description 15
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 13
- 229910052751 metal Inorganic materials 0.000 description 12
- 239000002184 metal Substances 0.000 description 12
- 239000002612 dispersion medium Substances 0.000 description 10
- 238000003917 TEM image Methods 0.000 description 8
- 238000004458 analytical method Methods 0.000 description 8
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 8
- 229910052697 platinum Inorganic materials 0.000 description 8
- 239000002994 raw material Substances 0.000 description 8
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 7
- 230000003197 catalytic effect Effects 0.000 description 7
- 238000005259 measurement Methods 0.000 description 7
- 239000000243 solution Substances 0.000 description 7
- 239000000126 substance Substances 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 5
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 description 5
- 239000002923 metal particle Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 238000011068 loading method Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000008188 pellet Substances 0.000 description 4
- 238000010298 pulverizing process Methods 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 3
- 238000000354 decomposition reaction Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 3
- 229910052763 palladium Inorganic materials 0.000 description 3
- 239000011802 pulverized particle Substances 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 238000004438 BET method Methods 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 229910002651 NO3 Inorganic materials 0.000 description 2
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000001747 exhibiting effect Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000009616 inductively coupled plasma Methods 0.000 description 2
- 238000013507 mapping Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 2
- 238000004626 scanning electron microscopy Methods 0.000 description 2
- 238000007873 sieving Methods 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 239000004115 Sodium Silicate Substances 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 150000004703 alkoxides Chemical class 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 230000000844 anti-bacterial effect Effects 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 238000003421 catalytic decomposition reaction Methods 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000004993 emission spectroscopy Methods 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 238000009532 heart rate measurement Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 1
- 238000004898 kneading Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 1
- 239000011812 mixed powder Substances 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 229910052762 osmium Inorganic materials 0.000 description 1
- SYQBFIAQOQZEGI-UHFFFAOYSA-N osmium atom Chemical compound [Os] SYQBFIAQOQZEGI-UHFFFAOYSA-N 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 238000006068 polycondensation reaction Methods 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 239000011164 primary particle Substances 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 229910052911 sodium silicate Inorganic materials 0.000 description 1
- 238000002336 sorption--desorption measurement Methods 0.000 description 1
- 238000000629 steam reforming Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
- 238000004846 x-ray emission Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/03—Catalysts comprising molecular sieves not having base-exchange properties
- B01J29/035—Microporous crystalline materials not having base exchange properties, such as silica polymorphs, e.g. silicalites
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/02—Impregnation, coating or precipitation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/04—Mixing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/16—Reducing
- B01J37/18—Reducing with gases containing free hydrogen
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Catalysts (AREA)
Abstract
The invention aims to provide a catalyst carrier with periodic mesopores and heat resistance, a catalyst and a manufacturing method thereof. The catalyst carrier (1) of the present invention comprises: a porous silica particle (2) having a plurality of mesopores (4) having a peak pore diameter of 2 to 50nm, which has been analyzed by the BJH method, and the plurality of mesopores (4) forming a periodic structure; and metal oxide particles (3) containing at least 1 element selected from the group consisting of Al, ti, mg, zr, fe, ce and Si; and the metal oxide particles (3) are present in at least the voids (5) between the porous silica particles (2).
Description
Technical Field
The present invention relates to a catalyst carrier, a catalyst, and a method for producing the same. The catalyst is a porous silica having a platinum group metal supported on a carrier containing a metal oxide, and is used, for example, as a decomposition material for malodorous substances, a decomposition material for ethylene which reduces freshness, or a mildew-proof and antibacterial material.
Background
A catalyst support comprising a mesoporous silica alumina gel has been proposed (for example, see patent document 1). Further, an ethylene decomposer for decomposing ethylene into carbon dioxide and water in an atmosphere of-1 to-40 ℃ with platinum supported on mesoporous silica has been proposed as a catalyst for catalytic decomposition reaction of ethylene (for example, see patent document 2).
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open No. 2002-284520
Patent document 2: japanese patent laid-open publication No. 2017-23889
Disclosure of Invention
[ Problem to be solved by the invention ]
In the method of producing a silica alumina gel having mesopores from a silica raw material and an alumina raw material by a wet method as in the catalyst support of patent document 1, the obtained silica alumina gel cannot have periodic mesopores as an important element for exhibiting a catalytic function. The catalyst of patent document 2 has periodic mesopores, but has the following problems: in the case where the support is mesoporous silica, the metal nanoparticles supported in the micropores are likely to sinter by heating at high temperature, and thus the catalyst activity is lowered.
In addition, the catalyst may be supported on a support such as a nonwoven fabric for use. Conventionally, the nonwoven fabric is usually processed by the following method: immersing or coating a support in a dispersion of the catalyst powder to adhere the support; alternatively, the catalyst powder is mixed into the matrix of the support, and the support is sandwiched between the front and back face materials. However, these methods have a problem in that the catalyst is easily detached from the support. Therefore, a method of fusion-bonding the catalyst to the surface of the support is preferable, but as described above, if heated at high temperature, the catalyst activity of the mesoporous silica is lowered, and thus it is difficult to achieve. A catalyst support having both periodic mesopores and heat resistance has not been achieved so far.
The invention aims to provide a catalyst carrier with periodic mesopores and heat resistance, a catalyst and a manufacturing method thereof.
[ Means of solving the problems ]
The catalyst carrier of the present invention is characterized by comprising: porous silica particles having a plurality of mesopores with a peak pore diameter of 2 to 50nm, which have been analyzed by the BJH (Barrett-Joyner-Halenda) method, and which form a periodic structure; and metal oxide particles containing at least 1 element selected from the group consisting of Al, ti, mg, zr, fe, ce and Si; and the metal oxide particles are present in at least the voids between the porous silica particles.
In the catalyst support of the present invention, the Na content of the metal oxide particles is preferably 100ppm or less. Since the state of high regularity of the periodic structure can be maintained without damaging the mesopores, a catalyst having a higher catalyst activity can be obtained.
In the catalyst support of the present invention, the mass ratio of the porous silica particles to the metal oxide particles (the content of the porous silica particles/the content of the metal oxide particles) is preferably 0.1 to 20. Excellent in formability and capable of exhibiting a sufficient catalytic function.
The catalyst carrier of the present invention comprises the following forms: the mesoporous has a peak pore diameter of 2-6 nm, which is analyzed by BJH method, and the catalyst carrier has a peak originating from the (100) plane in a range of 1-5 DEG of diffraction angle (2 theta) in X-ray diffraction of CuK alpha rays.
The catalyst carrier of the present invention comprises the following forms: the metal oxide particles are bonded to the surfaces of the porous silica particles.
The catalyst of the invention is characterized in that: the platinum group metal nano-particles are supported on the catalyst carrier, the catalyst is in a particle shape, the particle size of the catalyst is 25-500 mu m, and the platinum group metal nano-particles at least exist in the mesopores.
In the catalyst of the present invention, the content of the platinum group metal nanoparticles is preferably 1 to 20 mass%.
The catalyst of the present invention is preferably a linear structure which is fusion-bonded to the surface of a nonwoven fabric and does not contain the platinum group metal nanoparticles. Even when the heat treatment is performed, a sufficient catalytic function can be exhibited.
The method for producing a catalyst carrier of the present invention is characterized by comprising: a mixing step of mixing a powder of porous silica particles having a plurality of mesopores with a peak pore diameter of 2 to 50nm analyzed by a BJH method, with a sol containing a metal oxide precursor or a metal oxide containing at least 1 element selected from the group consisting of Al, ti, mg, zr, fe, ce and Si, to prepare a mixture of the powder of porous silica particles and the sol; a molding step of forming a molded article of the mixture; and a firing step of firing the molded article to prepare metal oxide particles containing at least 1 element selected from the group consisting of Al, ti, mg, zr, fe, ce and Si from the metal oxide precursor or the metal oxide.
In the method for producing a catalyst support of the present invention, the Na content of the metal oxide precursor or the metal oxide is preferably 100ppm or less. Since the state of high regularity of the periodic structure can be maintained without damaging the mesopores, a catalyst having a higher catalyst activity can be obtained.
The method for producing a catalyst of the present invention is characterized by comprising the steps of: mixing the catalyst support produced in the method for producing a catalyst support of the present invention with a platinum group metal compound; and reducing a mixture of the catalyst support and the platinum group metal compound.
[ Effect of the invention ]
According to the present invention, a catalyst carrier having both periodic mesopores and heat resistance, a catalyst, and a method for producing the same can be provided.
Drawings
Fig. 1 is a schematic view showing an example of a catalyst carrier according to the present embodiment.
Fig. 2 is a schematic diagram showing an example of a catalyst in which platinum group metal nanoparticles are supported on the catalyst carrier of fig. 1.
Fig. 3 (a) is an analysis result obtained by scanning electron microscope/energy dispersive X-ray spectrometry (SEM-EDX) of the surface of the catalyst carrier of example 1, and is an SEM observation image of the surface of the catalyst carrier. The image obtained by processing the SEM-EDX element map image into gray scale is shown in fig. 3 (a), but the SEM-EDX element map image is more accurately represented by processing the color image before gray tone.
Fig. 3 (b) is an analysis result obtained by scanning electron microscope/energy dispersive X-ray spectrometry (SEM-EDX) of the surface of the catalyst support of example 1, and is an SEM-EDX element map image of Al. The image obtained by processing the SEM-EDX element map image into gray scale is shown in fig. 3 (b), but the SEM-EDX element map image is more accurately represented by processing the color image before gray tone.
Fig. 3 (c) is an analysis result obtained by scanning electron microscope/energy dispersive X-ray spectrometry (SEM-EDX) of the surface of the catalyst support of example 1, and is an SEM-EDX element map image of Si. The image obtained by processing the SEM-EDX element map image into gray scale is shown in fig. 3 (c), but the SEM-EDX element map image is more accurately represented by processing the color image before gray tone.
Fig. 4 (a) is an analysis result obtained by scanning electron microscope/energy dispersive X-ray spectrometry (SEM-EDX) of the surface of the catalyst support of comparative example 1, and is an SEM observation image of the surface of the catalyst support. Fig. 4 (a) shows an image obtained by processing the SEM-EDX element map image into a gray scale, but the SEM-EDX element map image is more accurately represented by processing a color image before gray tone.
Fig. 4 (b) is an analysis result obtained by scanning electron microscope/energy dispersive X-ray spectrometry (SEM-EDX) of the surface of the catalyst support of comparative example 1, and is an SEM-EDX element map image of Al. Fig. 4 (b) shows an image obtained by processing the SEM-EDX element map image into a gray scale, but the SEM-EDX element map image is more accurately represented by processing a color image before gray tone.
Fig. 4 (c) is an analysis result obtained by scanning electron microscope/energy dispersive X-ray spectrometry (SEM-EDX) of the surface of the catalyst support of comparative example 1, and is an SEM-EDX element map image of Si. Fig. 4 (c) shows an image obtained by processing the SEM-EDX element map image into a gray scale, but the SEM-EDX element map image is more accurately represented by processing a color image before gray tone.
Fig. 5 is an XRD (X ray diffraction, X-ray diffraction) pattern of example 1.
FIG. 6 shows the results of measurement of the ethylene removal rate in example 1.
FIG. 7 shows the results of measurement of the ethylene removal rate in comparative example 2.
Fig. 8 (a) is a TEM (Transmission Electron Microscope ) image of a sample obtained by heating the catalyst of comparative example 2 at 250 ℃ for 20 hours, and is a raw image.
Fig. 8 (b) is a TEM image of a sample obtained by heating the catalyst of comparative example 2 at 250 ℃ for 20 hours, and is a processed image.
Fig. 9 is the XRD patterns of examples 1 and 5.
Fig. 10 (a) is a TEM image of example 1, and is a raw image.
Fig. 10 (b) is a TEM image of example 1 and is a processed image.
Detailed Description
Next, the present invention will be described in detail with reference to the embodiments, but the present invention is not limited to these descriptions and is explained. The embodiment may be variously changed as long as the effects of the present invention are exhibited.
Fig. 1 is a schematic view showing an example of a catalyst carrier according to the present embodiment. The catalyst carrier 1 of the present embodiment includes: porous silica particles 2 having a plurality of mesopores 4 having a peak pore diameter of 2 to 50nm, which have been analyzed by the BJH method, and the plurality of mesopores 4 forming a periodic structure; and metal oxide particles 3 containing at least 1 element selected from the group consisting of Al, ti, mg, zr, fe, ce and Si; and the metal oxide particles 3 are present in at least the gaps 5 between the porous silica particles 2. Fig. 1 is a schematic diagram showing that the ratio of the sizes of the components is different from the ratio of the sizes of the components of the physical catalyst support.
The porous silica particles 2 are also called mesoporous silica, and are composed mainly of silica having a porous structure and containing a plurality of mesopores 4. In fig. 1, the porous silica particles 2 are schematically shown in a spherical shape, but the shape of the porous silica particles 2 is not limited to this. The porous silica particles 2 may be pulverized particles obtained by pulverizing a sintered product of porous silica.
The peak pore diameter of the mesopores 4 is 2 to 50nm, more preferably 2 to 10nm. In the present specification, the peak pore diameter of the mesopores 4 is analyzed by the BJH method. The mesopores 4 have a periodic structure in which micropores are regularly arranged. In fig. 1, the cross-sectional shape of the mesopores 4 is schematically shown as a hexagon, but the cross-sectional shape of the mesopores 4 is not limited thereto. The periodic structure of the mesopores 4 may be, for example, a two-dimensional hexagonal structure (shown in fig. 1) in which cylindrical pores are filled in a honeycomb shape, or a cubic structure (not shown) in which spherical pores are most densely filled.
The catalyst carrier 1 of the present embodiment includes the following modes: the mesoporous 4 has a peak pore diameter of 2 to 6nm as analyzed by BJH method, and the catalyst support 1 has a peak originating from the (100) plane in a range of 1 to 5 DEG of diffraction angle (2 theta) in X-ray diffraction of CuK alpha rays. The catalyst support 1 has a peak originating from the (100) plane in the range of 1 to 5 ° in the diffraction angle (2θ) in the X-ray diffraction of cukα rays, meaning that the porous silica 2 has a periodic structure of mesopores 4. The XRD pattern of the porous silica 2 as the raw material of the catalyst carrier 1 is the same as that of the catalyst carrier 1. When the peak pore diameter of the mesopores 4 exceeds 6nm, the peak of the diffraction angle (2θ) of the catalyst support 1 in the X-ray diffraction of the cukα ray is shifted to the low angle side of less than 1 °, and it is substantially difficult to confirm the periodic structure of the mesopores 4 by the X-ray diffraction. In this case, the periodic structure of the mesopores 4 can be confirmed by observation with TEM (Transmission ElectronMicroscope). In the TEM image, the periodic structure of the mesopores 4 is observed as a regular fringe pattern, for example.
The average particle diameter of the porous silica particles 2 is preferably 5 to 300. Mu.m, more preferably 5 to 50. Mu.m. If the average particle diameter of the porous silica particles 2 is less than 5 μm, voids between the porous silica particles 2 become small, and thus it may be difficult to make the metal oxide particles exist in the voids. If the average particle diameter of the porous silica particles 2 exceeds 300 μm, the voids between the porous silica particles 2 become large, and therefore the amount of metal oxide particles required to function as a binder for binding the porous silica particles 2 to each other may become large. In addition, if the amount of the metal oxide particles is small, the adhesion of the porous silica particles 2 to each other may be weakened. The average particle diameter is, for example, a value obtained by using a particle size distribution analyzer. In the catalyst support 1, the porous silica particles 2 may be present in the form of primary particles. In addition, when the porous silica particles 2 are pulverized particles obtained by pulverizing a sintered product of porous silica, the average particle diameter of the porous silica particles is the average particle diameter of the pulverized particles.
The porous silica particles 2 are obtained by the following production method, for example. An inorganic raw material such as sodium silicate is added to an aqueous solution containing an organic raw material such as a surfactant, the solution is adjusted to a predetermined pH value, and then the reaction mixture is kept at a predetermined temperature to carry out a polycondensation reaction, whereby a complex of an organic substance and an inorganic substance is formed around the organic substance with the organic substance as a mold. Then, the obtained composite is baked at 400 to 800 ℃ to remove the organic matter, thereby obtaining a sintered product of porous silica. The sintered product of porous silica is pulverized to obtain porous silica particles 2.
The metal oxide particles 3 include at least 1 element selected from the group consisting of Al, ti, mg, zr, fe, ce and Si. The metal oxide particles 3 may be single oxides having 1 metal species or double oxides having 2 or more metal species. Among them, the metal oxide particles 3 preferably contain Al, more preferably alumina.
In the catalyst support 1, the metal oxide particles 3 are nanoparticles having a particle diameter of nm. The upper limit value of the particle diameter of the metal oxide particles 3 is, for example, preferably 500nm or less, more preferably 100nm or less, and particularly preferably 50nm or less. The lower limit value of the particle diameter of the metal oxide particles 3 is preferably 1nm or more, more preferably 5nm or more, and particularly preferably 10nm or more. As the average particle diameter of the metal oxide particles 3, metal oxide particles 3 whose average particle diameter is appropriately adjusted according to the size of the porous silica particles 2 are used.
The metal oxide particles 3 are present in at least the gaps 5 between the porous silica particles 2. The voids 5 between the porous silica particles 2 are regions surrounded by the interfaces of the porous silica particles 2. The metal oxide particles 3 function as a binder for binding the porous silica particles 2 to each other. The metal oxide particles 3 are preferably present between the porous silica particles 2, such as the contact portions 6 where the porous silica particles 2 contact each other, in addition to the gaps 5 between the porous silica particles 2. The metal oxide particles 3 may be present on the surfaces of the porous silica particles 2 or may be interposed between the porous silica particles 2. The surface of the porous silica particles 2 includes the inside of the mesopores 4 and the surface other than the mesopores 4.
In the catalyst support 1 of the present embodiment, the mass ratio of the porous silica particles 2 to the metal oxide particles 3 (the content of the porous silica particles 2/the content of the metal oxide particles 3) is preferably 0.1 to 20. The content of the porous silica particles 2/the content of the metal oxide particles 3 is more preferably 0.2 to 10, particularly preferably 0.25 to 9. If the mass ratio of the porous silica particles 2 to the metal oxide particles 3 (the content of the porous silica particles 2/the content of the metal oxide particles 3) is less than 0.1, the content of the porous silica particles 2 becomes too small, and the amount of the platinum group metal nanoparticles that can be supported becomes small, and thus the catalytic function may not be sufficiently exhibited. When the mass ratio of the porous silica particles 2 to the metal oxide particles 3 (the content of the porous silica particles 2/the content of the metal oxide particles 3) exceeds 20, the content of the metal oxide particles 3 becomes too small, and the binder function may not be sufficiently exhibited.
The catalyst carrier 1 of the present embodiment includes the following modes: the metal oxide particles 3 are bonded to the surfaces of the porous silica particles 2. The bonding is produced by sintering the porous silica particles 2 and the metal oxide particles 3. The bond may be formed between the porous silica particles 2 or between the metal oxide particles 3. The catalyst support 1 comprises a metal oxide phase and a silica phase. The catalyst support 1 is preferably such that the metal oxide does not react with the porous silica. The catalyst support 1 is preferably formed into a block.
Fig. 2 is a schematic diagram showing an example of a catalyst in which platinum group metal nanoparticles are supported on the catalyst carrier of fig. 1. The catalyst 10 of the present embodiment supports platinum group metal nanoparticles 7 on the catalyst support 1 of the present embodiment, and the platinum group metal nanoparticles 7 are present at least in the mesopores 4. The platinum group metal nanoparticles 7 may be present in the surface of the porous silica particles 2 other than the mesopores 4, the gaps 5 between the porous silica particles 2, the contact portions 6 between the porous silica particles 2, the surface of the metal oxide particles 3, the gaps between the metal oxide particles 3, or the contact portions between the metal oxide particles 3, in addition to the mesopores 4. Fig. 2 is a schematic diagram showing that the ratio of the sizes of the components is different from the ratio of the sizes of the components of the physical catalyst support.
The platinum group metal nanoparticle 7 preferably contains at least 1 element selected from the group consisting of platinum, ruthenium, iridium, rhodium, palladium, and osmium, for example. The platinum group metal nanoparticles 7 may be single metal particles or alloy particles of the population. Among them, the platinum group metal nanoparticles 7 are preferably platinum particles or palladium particles.
The average particle diameter of the platinum group metal nanoparticles 7 is preferably 1 to 5nm, more preferably 1 to 3nm. When the average particle diameter of the platinum group metal nanoparticle 7 is less than 1nm, sintering may be easily generated by heating, and the catalyst activity may be lowered. When the average particle diameter of the platinum group metal nanoparticle 7 exceeds 5nm, the catalytic function may not be sufficiently exhibited. In order to facilitate the loading in the mesopores 4, the average particle diameter of the platinum group metal nanoparticles 7 is preferably a peak pore diameter of Yu Jiekong a smaller than that of the mesopores 4. The average particle diameter is, for example, a value obtained by using CO pulse measurement.
In the catalyst 10 of the present embodiment, the content of the platinum group metal nanoparticles 7 is preferably 1 to 20 mass%, more preferably 1 to 7 mass%. When the content of the platinum group metal nanoparticles 7 is less than 1 mass%, the catalytic function may not be sufficiently exhibited. When the content of the platinum group metal nanoparticles 7 exceeds 20 mass%, sintering may occur due to heating.
The catalyst 10 of the present embodiment is preferably fusion-bonded to the surface of the nonwoven fabric, and does not include the linear structure of the platinum group metal nanoparticles 7. In the case of, for example, performing a heat treatment at 150 to 200 ℃ to melt-bond and immobilize a catalyst on the surface of a nonwoven fabric for processing, if the carrier is composed of only mesoporous silica and does not contain metal oxide particles as in the catalyst of, for example, patent document 2, the following problems are present: since the platinum group metal nanoparticle supported in the pore is easily sintered, a linear structure of the platinum group metal nanoparticle is produced, and the catalyst activity is reduced. In contrast, in the catalyst 10 of the present embodiment, the support contains the metal oxide particles 3 in addition to the porous silica particles 2, and therefore, even if the heat treatment is performed, the platinum group metal nanoparticles 7 are not sintered, and thus the linear structures of the platinum group metal nanoparticles 7 are not generated. Thus, the catalyst activity is not lowered. Therefore, the catalyst of the present embodiment can be applied to not only a case where the catalyst is melt-fixed to the surface of a nonwoven fabric but also a case where the catalyst is used at a high temperature. The use at high temperatures is for example in the case of hydrogen production by steam reforming of methane with Pd catalysts or the like at 150 to 200 ℃. In addition, the catalyst used, in which the catalyst activity is reduced by use, can be regenerated by heat treatment. The method for regenerating the used catalyst is not particularly limited, and may be carried out by heating at 1℃for 2 hours under normal pressure, for example.
The catalyst 10 of the present embodiment is in the form of particles, and the particle diameter of the catalyst 10 is 25 to 500 μm. The particle diameter of the catalyst 10 is more preferably 50 to 100. Mu.m. Examples of the particle form include: a molded article such as a pellet, a cylinder, or a granule, or a powder obtained by pulverizing such a molded article. When the particle diameter of the catalyst 10 is less than 25 μm, the catalyst activity may be reduced by heating. If the particle diameter of the catalyst 10 exceeds 500. Mu.m, it is difficult to carry out the process of supporting the catalyst on the substrate.
The BET (Brunauer-Emmett-Teller) specific surface area of the catalyst 10 of the present embodiment is preferably 500m 2/g or more, more preferably 600m 2/g or more. When the BET specific surface area is less than 500m 2/g, insufficient loading of platinum group metal nanoparticles in mesopores may be caused. The BET specific surface area can be calculated by a BET method based on nitrogen adsorption and desorption. The upper limit of the BET specific surface area is not particularly limited, but is preferably 1500m 2/g or less, more preferably 1000m 2/g or less.
The method for producing a catalyst carrier according to the present embodiment includes: a mixing step of mixing a powder of porous silica particles having a plurality of mesopores with a peak pore diameter of 2 to 50nm analyzed by a BJH method, with a sol containing a metal oxide precursor or a metal oxide containing at least 1 element selected from the group consisting of Al, ti, mg, zr, fe, ce and Si, to prepare a mixture of the powder of porous silica particles and the sol; a molding step of forming a molded article of the mixture; and a firing step of firing the molded article to prepare metal oxide particles containing at least 1 element selected from the group consisting of Al, ti, mg, zr, fe, ce and Si from the metal oxide precursor or the metal oxide.
In the mixing step, a powder of porous silica particles is blended and kneaded into a sol containing a metal oxide precursor or a metal oxide. In this case, various additives such as a molding aid may be blended. In the catalyst support obtained, the porous silica particles and the metal oxide particles are uniformly distributed by acting as shearing force or the like during kneading. The sol containing the metal oxide precursor is a colloidal solution of colloidal particles in which the metal oxide precursor is dispersed in a dispersion medium. The sol containing the metal oxide is a colloidal solution in which colloidal particles of the metal oxide are dispersed in a dispersion medium. The dispersion medium is not particularly limited, and is, for example, water or dilute nitric acid. The metal oxide precursor is a substance that becomes a metal oxide by firing, and is, for example, a salt of a metal element constituting the metal oxide, an alkoxide of a metal element constituting the metal oxide, or a complex of a metal element constituting the metal oxide. Among them, the metal oxide precursor is preferably a salt of a metal element. The salt of the metal element is, for example, hydroxide, chloride, nitrate, carbonate, sulfate or a complex salt thereof or a hydrate thereof. When the metal oxide particles 3 are alumina particles, the metal oxide precursor is, for example, aluminum oxyhydroxide, which becomes aluminum oxide (aluminum oxide) by calcination. The mixing step preferably comprises the steps of: a kneaded product of a powder of porous silica particles and a sol containing a metal oxide precursor or a metal oxide. The dispersion medium containing the metal oxide precursor or the sol of the metal oxide is preferably absorbed by the powder of the porous silica particles in the mixing step. When the dispersion medium is absorbed by the powder of porous silica particles, the metal oxide precursor or the metal oxide permeates at least into the gaps between the porous silica particles together with the dispersion medium. In this case, the metal oxide precursor or the metal oxide may be attached to the porous silica particles 2 together with the dispersion medium, and the surfaces of the porous silica particles 2 may be attached to each other. The metal oxide precursor or the metal oxide may be interposed between the porous silica particles 2 together with the dispersion medium.
In the method for producing a supported catalyst according to the present embodiment, the metal oxide precursor or the metal oxide as the raw material of the metal oxide particles preferably has a low Na content. The Na content of the metal oxide precursor or the metal oxide is preferably 100ppm or less, more preferably 20ppm or less. Since the state of high regularity of the periodic structure can be maintained without damaging the mesopores, a catalyst having a higher catalyst activity can be obtained. If the Na content exceeds 100ppm, mesopores may be destroyed to decrease the regularity of the periodic structure, and platinum group metal nanoparticles may not be supported in micropores, and thus the catalyst activity may not be sufficiently exhibited. The method for measuring the Na content of the metal oxide precursor or the metal oxide is not particularly limited, and may be measured by a conventionally known method, for example, by fluorescence X-ray analysis (XRF) or ICP (Inductively Coupled Plasma ) emission spectrometry (ICP-OES). By using the metal oxide precursor or the metal oxide having a Na content of 100ppm or less as a raw material, the Na content of the metal oxide particles in the obtained supported catalyst becomes the same Na content as that of the raw material, that is, 100ppm or less.
In the molding step, a mixture of the powder of porous silica particles and the metal oxide precursor or the sol of the metal oxide is molded into, for example, a pellet shape. The shape of the molded article is not limited to the pellet shape, and may be, for example, a cylindrical shape or a pellet shape. The size of the molded article is preferably 1 to 8mm, more preferably 1 to 4mm.
In the firing step, the firing temperature is preferably 500 to 700 ℃, more preferably 500 to 600 ℃. The baking time is preferably 90 to 180 minutes, more preferably 120 to 180 minutes. The firing method is not particularly limited, and for example, firing can be performed using an electric furnace. The dispersion medium in the mixture is volatilized by firing, and the colloidal particles of the metal oxide precursor or the colloidal particles of the metal oxide dispersed in the sol become metal oxide particles present in the interstices between the porous silica particles. The colloidal particles of the metal oxide may be directly formed into metal oxide particles without aggregation, or may be aggregated into metal oxide particles. The metal oxide particles may be present between porous silica particles such as contact portions where the porous silica particles contact each other, in addition to the voids between the porous silica particles. The metal oxide particles may be present on the surface of the porous silica particles, or may be interposed between the porous silica particles. The method may further include a step of pulverizing the sintered body after the firing step.
The method for producing the catalyst of the present embodiment includes the steps of: mixing the catalyst support produced in the method for producing a catalyst support of the present embodiment with a platinum group metal compound; and reducing the mixture of the catalyst support and the platinum group metal compound.
The platinum group metal compound is, for example, an inorganic acid salt such as hydrochloride, nitrate or sulfate of a platinum group metal, or an organic complex of a platinum group metal. The platinum group metal compound is preferably dissolved in a solvent such as water, hydrochloric acid, nitric acid or sulfuric acid.
The reduction method is not particularly limited, and is, for example, a method of treatment with a reducing agent, heat, light, or the like. The platinum group metal is nucleated and grown into grains in a solution of a platinum group metal compound in which porous silica particles are present by reduction, thereby forming platinum group metal nanoparticles. At this time, the platinum group metal nanoparticles are supported in the mesopores of the porous silica particles. The platinum group metal nanoparticle may be present in the mesopores of the porous silica particles, in addition to the mesopores. The mesopores are, for example, surfaces of the porous silica particles other than the mesopores, voids between the porous silica particles, contact portions between the porous silica particles, surfaces of the metal oxide particles, voids between the metal oxide particles, or contact portions between the metal oxide particles. However, it is considered that the platinum group metal nanoparticles related to the catalytic function are particles mainly supported in the mesopores of the porous silica particles.
The method for producing a catalyst preferably further comprises the steps of: crushing the catalyst obtained in the reduction; and sieving to obtain catalyst powder with specified particle size. The specific particle diameter is, for example, 25 to 500. Mu.m.
Examples
Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the examples. In the examples, "parts" and "% by mass" are represented by "parts by mass" and "% by mass", respectively, unless otherwise specified. The addition fraction is a value in terms of solid content.
Example 1
(Production of catalyst Carrier)
Mesoporous silica (TMPS-4R, peak pore diameter 4nm, average particle diameter 50 μm, manufactured by Sun chemical Co., ltd.) was kneaded with a sol containing aluminum oxyhydroxide having a Na content of 100ppm or less as a metal oxide precursor to prepare a mixture. At this time, the adjustment ratio of the mesoporous silica to the colloidal particles of the aluminum oxyhydroxide in the sol containing the aluminum oxyhydroxide as the metal oxide precursor was 90 in terms of mass ratio: 10. in the resulting mixture, the dispersion medium containing the sol of aluminum oxyhydroxide as a metal oxide precursor is absorbed by the mesoporous silica. The mixture is formed into a particulate shaped article. The size of the granular molded article was set to be 1.4X4 mm. The molded article was baked at 500 to 600℃for 3 hours using an electric furnace to obtain a sintered body. The sintered body was used as the catalyst carrier of example 1.
(Production of catalyst)
A catalyst in which platinum as platinum group metal nanoparticles was supported on the obtained catalyst support of example 1 was produced in the following manner. The obtained catalyst carrier (10 g) was immersed in 50ml of water, and a chloroplatinic acid solution [ H 2PtCl6 aq. ] was dropped into the immersion liquid so that the platinum loading became 1.0 mass%. The solvent was evaporated by heating to 70 ℃ using an evaporator to obtain a solid. The solid obtained was dried under vacuum at 70℃for 16-1 8 hours. Then, the catalyst having platinum supported on the catalyst carrier was obtained by conducting a reduction treatment at 150℃for 2 hours while allowing hydrogen gas to flow at 500 ml/min. Then, the obtained catalyst was pulverized, and the particle diameter was sieved to 25 to 500. Mu.m, and the catalyst having a particle diameter of 25 to 500. Mu.m was used as the catalyst of example 1.
Example 2
In the production of the catalyst support of example 1, the blending ratio of the mesoporous silica to the alumina hydroxide in the sol containing the alumina hydroxide having a Na content of 100ppm or less as the metal oxide precursor was changed to 20 in terms of mass ratio: 80, a catalyst was obtained in the same manner as in example 1.
Example 3
A catalyst was obtained in the same manner as in example 1, except that the platinum loading was changed to 10 mass% in the production of the catalyst of example 1.
Example 4
In the production of the catalyst of example 1, platinum group metal nanoparticles supported on a catalyst support were replaced with palladium. A catalyst was obtained in the same manner as in example 1, except that a sodium chloropalladate solution [ Na 2PdCl4 aq ] was used as the metal salt solution instead of the chloroplatinic acid solution.
Example 5
(Production of catalyst Carrier)
A catalyst carrier was obtained in the same manner as in example 1, except that an alumina sol having a Na content of 300ppm or more was used as a metal oxide precursor instead of an alumina sol having a Na content of 100ppm or less in the production of the catalyst carrier of example 1.
(Production of catalyst)
A catalyst was produced on the obtained catalyst support in the same manner as in the production method of the catalyst of example 1, and the catalyst was used as the catalyst of example 5.
Comparative example 1
(Production of catalyst Carrier)
A mixed powder of mesoporous silica (TMPS-4R, peak pore diameter 4nm, average particle diameter 50 μm) and alumina powder (average particle diameter 40 μm) was used as a catalyst support.
(Production of catalyst)
Platinum was supported on the obtained catalyst carrier in the same manner as in the production method of the catalyst of example 1, and then the obtained catalyst was pulverized, and the particle size was sieved to 25 to 500 μm, and the catalyst having a particle size of 25 to 500 μm was used as the catalyst of comparative example 1.
Comparative example 2
A catalyst was obtained in the same manner as in example 1, except that the mesoporous silica (manufactured by Sun chemical Co., ltd., TMPS-4R, peak pore diameter: 4nm, average particle diameter: 50 μm) used in example 1 was directly used as a catalyst support.
Comparative example 3
A catalyst was obtained in the same manner as in example 1, except that the catalyst having a particle diameter of less than 25 μm was obtained by sieving the catalyst having a particle diameter of less than 25 μm in the production of the catalyst of example 1.
(SEM observation)
SEM observation was performed on the catalyst support of example 1 and the catalyst support of comparative example 1. Fig. 3 (a), 3 (b) and 3 (c) show analysis results obtained by scanning electron microscopy/energy dispersive X-ray spectrometry (SEM-EDX) of the surface of the catalyst carrier of example 1, and fig. 4 (a), 4 (b) and 4 (c) show analysis results obtained by scanning electron microscopy/energy dispersive X-ray spectrometry (SEM-EDX) of the surface of the catalyst carrier of comparative example 1. Fig. 3 (a) and 4 (a) are SEM observation images of the surface of the catalyst support, fig. 3 (b) and 4 (b) are SEM-EDX element mapping images of Al, and fig. 3 (c) and 4 (c) are SEM-EDX element mapping images of Si. In fig. 3 and 4, the observation magnification is 500 times, and the scale at the lower left is 100 μm. As shown in fig. 3 (b) and 3 (c), the alumina and silica of the catalyst support of example 1 were substantially uniformly distributed. On the other hand, as shown in fig. 4 (b) and 4 (c), it was observed that the alumina of the catalyst support of comparative example 1 had an island shape with a diameter of several tens μm. In fig. 3 and 4, the image obtained by processing the SEM-EDX element map image into gray scale is shown, but the SEM-EDX element map image is more accurately represented by the color image before processing into gray tone.
(BET specific surface area)
The specific surface areas of the catalysts of examples 1 to 4 and the catalysts of comparative examples 1 to 3 were determined by the BET method using adsorption isotherms obtained by nitrogen adsorption/desorption measurement. The results are shown in Table 1.
TABLE 1
| BET specific surface area [ m 2/g ] | |
| Example 1 | 670 |
| Example 2 | 305 |
| Example 3 | 608 |
| Example 4 | 635 |
| Comparative example 1 | 695 |
| Comparative example 2 | 794 |
| Comparative example 3 | 618 |
(XRD analysis)
XRD measurements were performed on the catalyst support of example 1. XRD measurement conditions were at room temperature and λ=cukα. Fig. 5 is the XRD pattern of example 1. As shown in fig. 5, the catalyst support of example 1 has a peak originating from the (100) plane in the range of 1 to 5 ° in the diffraction angle (2θ) in the X-ray diffraction of cukα rays. Therefore, it was confirmed that the mesopores of the porous silica had a periodic structure.
XRD measurement was performed on the catalyst support of example 5 in the same manner as the catalyst support of example 1. Fig. 9 is the XRD patterns of examples 1 and 5. In example 5, since a metal oxide precursor having a high Na content was used, 3 peaks in the range of 1 to 5 ° in diffraction angle (2θ) were all reduced as compared with example 1. Therefore, it was confirmed that the regularity of the periodic structure of the mesopores of the porous silica was reduced.
(Ethylene removal Rate)
The catalyst of example 1 was used as a non-heated product, the non-heated product of example 1 was heated at 150℃for 20 hours as a heated product 1, and the non-heated product of example 1 was heated at 200℃for 20 hours as a heated product 2. The ethylene removal rate was measured using the unheated products, heated products 1 and 2 in the following manner. The method for measuring the ethylene removal rate is as follows: in an airbag filled with a total of 2.6L of gas containing 100ppm of ethylene gas, 20% of oxygen gas and 80% of nitrogen gas, 0.6g of a catalyst was placed, and the ethylene concentration in the airbag was measured by a gas chromatography apparatus (GC-2030, manufactured by Shimadzu corporation) at a predetermined time, to calculate a reduction rate relative to the initial ethylene concentration. The catalyst of comparative example 2 was used as a non-heated product, the non-heated product of comparative example 2 was heated at 150℃for 20 hours as a heated product 1, the non-heated product of comparative example 2 was heated at 200℃for 20 hours as a heated product 2, and the non-heated product of comparative example 2 was heated at 100℃as a heated product 3. The ethylene removal rate was also measured in the same manner as in example 1 for the unheated products, heated product 1, heated product 2, and heated product 3 of comparative example 2. The results are shown in fig. 6 (example 1) and fig. 7 (comparative example 2). Both the heating product 1 and the heating product 2 of example 1 had a high ethylene removal rate. Therefore, it was confirmed that the platinum group metal nanoparticles were not sintered and the catalyst activity was not lowered even when the catalyst of example 1 was subjected to heat treatment. In addition, the unheated product of example 1 had lower ethylene removal rates than the heated products 1 and 2 due to the influence of the adhering water. On the other hand, with respect to the catalyst of comparative example 2, a decrease in the ethylene decomposition rate was observed in the heated product 3 as compared with the unheated product, and a significant decrease in the ethylene removal rate was observed in the heated product 1 and the heated product 2 as compared with the unheated product. Therefore, it was confirmed that the catalyst of comparative example 2 had reduced catalyst activity due to the heat treatment. Further, since the unheated product of comparative example 2 was stored in the dryer, there was little influence of the adhering water.
Fig. 8 (a) and 8 (b) are TEM images of samples obtained by heating the catalyst of comparative example 2 at 250 ℃ for 20 hours. Fig. 8 (b) is an image obtained by processing a linear structure surrounded by a ring, and fig. 8 (a) is an image before processing of fig. 8 (b). The TEM images of fig. 8 (a) and 8 (b) were observed at a magnification of 10 ten thousand times, and the scale at the lower right was 20.0nm. As shown in fig. 8 (a) and 8 (b), the platinum group metal nanoparticles of the catalyst of comparative example 2 were sintered and coarsened by heating, and a linear structure of the platinum group metal nanoparticles was formed. In fig. 8 (b), the linear shadow observed in the portion surrounded by the white circles is a linear structure of platinum group metal nanoparticles. It was predicted that, as shown in fig. 8 (a) and 8 (b), a linear structure of platinum group metal nanoparticles was formed in each of the heating products 1 and 2 of comparative example 2 used for measurement of the ethylene removal rate.
Fig. 10 (a) and 10 (b) are TEM images of example 1. Fig. 10 (b) is an image obtained by processing platinum group metal nanoparticles in mesopores indicated by arrows, and fig. 10 (a) is an image before processing in fig. 10 (b). The TEM images of fig. 10 (a) and 10 (b) were observed at a magnification of 10 ten thousand times, and the scale at the lower right was 20.0nm. As shown in fig. 10 (a) and 10 (b), in the catalyst of example 1, platinum group metal nanoparticles were spherically supported in mesopores.
[ Description of symbols ]
1. Catalyst carrier
2. Porous silica particles
3. Metal oxide particles
4. Mesoporous pores
5. Void space
6. Abutment portion
7. Platinum group metal nanoparticles
10. A catalyst.
Claims (11)
1. A catalyst support, characterized by comprising: porous silica particles having a plurality of mesopores with a peak pore diameter of 2 to 50nm, which have been analyzed by the BJH method, and the plurality of mesopores forming a periodic structure;
a metal oxide particle including at least 1 element selected from the group consisting of Al, ti, mg, zr, fe, ce and Si; and is also provided with
The metal oxide particles are present in at least the voids between the porous silica particles.
2. The catalyst support according to claim 1, characterized in that: the Na content of the metal oxide particles is 100ppm or less.
3. The catalyst support according to claim 1, characterized in that: the mass ratio of the porous silica particles to the metal oxide particles (the content of the porous silica particles/the content of the metal oxide particles) is 0.1 to 20.
4. The catalyst support according to claim 1, characterized in that: the peak pore diameter of the mesoporous analyzed by BJH method is 2-6 nm, and
The catalyst support has a peak originating from the (100) plane in a range of 1 to 5 DEG of diffraction angle (2 theta) in X-ray diffraction of CuK alpha rays.
5. The catalyst support according to claim 1, characterized in that: the metal oxide particles are bonded to the surfaces of the porous silica particles.
6. A catalyst, characterized in that: the catalyst carrier according to any one of claims 1 to 5, having platinum group metal nanoparticles supported thereon,
The catalyst is in a particle shape, the particle size of the catalyst is 25-500 mu m,
The platinum group metal nanoparticles are present at least within the mesopores.
7. The catalyst of claim 6, wherein: the content of the platinum group metal nano particles is 1 to 20 mass percent.
8. The catalyst of claim 6, wherein: the catalyst is melt-bonded to the surface of the nonwoven fabric, and does not contain the platinum group metal nanoparticles, and is formed into a linear structure.
9. A method for manufacturing a catalyst carrier, characterized by comprising: a mixing step of mixing a powder of porous silica particles having a plurality of mesopores with a peak pore diameter of 2 to 50nm analyzed by a BJH method, with a sol containing a metal oxide precursor or a metal oxide containing at least 1 element selected from the group consisting of Al, ti, mg, zr, fe, ce and Si, to prepare a mixture of the powder of porous silica particles and the sol;
A molding step of forming a molded article of the mixture; and
And a firing step of firing the molded article to prepare metal oxide particles containing at least 1 element selected from the group consisting of Al, ti, mg, zr, fe, ce and Si from the metal oxide precursor or the metal oxide.
10. The method for producing a catalyst carrier according to claim 9, characterized in that: the Na content of the metal oxide precursor or the metal oxide is 100ppm or less.
11. A method for producing a catalyst, characterized by comprising the steps of: mixing the catalyst carrier produced in the method for producing a catalyst carrier according to claim 9 or 10 with a platinum group metal compound; and
The mixture of the catalyst support and the platinum group metal compound is reduced.
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| PCT/JP2022/042313 WO2023090303A1 (en) | 2021-11-16 | 2022-11-15 | Catalyst carrier, catalyst, and methods respectively for producing those products |
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