CN115400752A - Pd-In intermetallic compound catalyst and preparation method and application thereof - Google Patents
Pd-In intermetallic compound catalyst and preparation method and application thereof Download PDFInfo
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- CN115400752A CN115400752A CN202211052126.4A CN202211052126A CN115400752A CN 115400752 A CN115400752 A CN 115400752A CN 202211052126 A CN202211052126 A CN 202211052126A CN 115400752 A CN115400752 A CN 115400752A
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- 239000003054 catalyst Substances 0.000 title claims abstract description 96
- 229910000765 intermetallic Inorganic materials 0.000 title claims abstract description 61
- 238000002360 preparation method Methods 0.000 title abstract description 12
- 229910052751 metal Inorganic materials 0.000 claims abstract description 68
- 239000002184 metal Substances 0.000 claims abstract description 68
- 239000000203 mixture Substances 0.000 claims abstract description 33
- 238000006243 chemical reaction Methods 0.000 claims abstract description 24
- IAYUQKZZQKUOFL-UHFFFAOYSA-N pyridine-2,3,5,6-tetramine Chemical compound NC1=CC(N)=C(N)N=C1N IAYUQKZZQKUOFL-UHFFFAOYSA-N 0.000 claims abstract description 21
- 230000009467 reduction Effects 0.000 claims abstract description 17
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 14
- 238000005984 hydrogenation reaction Methods 0.000 claims abstract description 10
- 239000012752 auxiliary agent Substances 0.000 claims abstract description 9
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 7
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 7
- 239000003575 carbonaceous material Substances 0.000 claims abstract description 4
- 238000005470 impregnation Methods 0.000 claims abstract description 4
- 239000002243 precursor Substances 0.000 claims abstract description 3
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 3
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 134
- 239000012266 salt solution Substances 0.000 claims description 53
- 238000001035 drying Methods 0.000 claims description 28
- 229910052763 palladium Inorganic materials 0.000 claims description 27
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 26
- 230000032683 aging Effects 0.000 claims description 24
- FTLHORLYDROOSU-UHFFFAOYSA-N indium(3+);trinitrate;pentahydrate Chemical compound O.O.O.O.O.[In+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O FTLHORLYDROOSU-UHFFFAOYSA-N 0.000 claims description 24
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- 239000002041 carbon nanotube Substances 0.000 claims description 20
- 229910021393 carbon nanotube Inorganic materials 0.000 claims description 20
- ZLJZDCVHRYAHAW-UHFFFAOYSA-N 3,5-dinitropyridine-2,6-diamine Chemical compound NC1=NC(N)=C([N+]([O-])=O)C=C1[N+]([O-])=O ZLJZDCVHRYAHAW-UHFFFAOYSA-N 0.000 claims description 16
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 12
- 229910052739 hydrogen Inorganic materials 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 11
- 150000003839 salts Chemical class 0.000 claims description 10
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 9
- 239000001257 hydrogen Substances 0.000 claims description 9
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 8
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 8
- 229910052738 indium Inorganic materials 0.000 claims description 7
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 claims description 6
- PSCMQHVBLHHWTO-UHFFFAOYSA-K indium(iii) chloride Chemical compound Cl[In](Cl)Cl PSCMQHVBLHHWTO-UHFFFAOYSA-K 0.000 claims description 6
- 239000012876 carrier material Substances 0.000 claims description 5
- 239000011261 inert gas Substances 0.000 claims description 5
- 239000002904 solvent Substances 0.000 claims description 5
- 150000002500 ions Chemical class 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 229910021618 Indium dichloride Inorganic materials 0.000 claims description 3
- 239000006229 carbon black Substances 0.000 claims description 3
- VOWMQUBVXQZOCU-UHFFFAOYSA-L dichloroindium Chemical compound Cl[In]Cl VOWMQUBVXQZOCU-UHFFFAOYSA-L 0.000 claims description 3
- 238000011068 loading method Methods 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 3
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 3
- JUBNUQXDQDMSKL-UHFFFAOYSA-N palladium(2+);dinitrate;dihydrate Chemical compound O.O.[Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O JUBNUQXDQDMSKL-UHFFFAOYSA-N 0.000 claims description 3
- PIBWKRNGBLPSSY-UHFFFAOYSA-L palladium(II) chloride Chemical compound Cl[Pd]Cl PIBWKRNGBLPSSY-UHFFFAOYSA-L 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
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- 230000000694 effects Effects 0.000 abstract description 8
- 239000013078 crystal Substances 0.000 abstract description 7
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 abstract 2
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 abstract 1
- 239000000243 solution Substances 0.000 description 23
- 239000012018 catalyst precursor Substances 0.000 description 22
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- LDXJRKWFNNFDSA-UHFFFAOYSA-N 2-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)-1-[4-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidin-5-yl]piperazin-1-yl]ethanone Chemical compound C1CN(CC2=NNN=C21)CC(=O)N3CCN(CC3)C4=CN=C(N=C4)NCC5=CC(=CC=C5)OC(F)(F)F LDXJRKWFNNFDSA-UHFFFAOYSA-N 0.000 description 6
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 6
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- 125000000449 nitro group Chemical group [O-][N+](*)=O 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
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- VZTDIZULWFCMLS-UHFFFAOYSA-N ammonium formate Chemical compound [NH4+].[O-]C=O VZTDIZULWFCMLS-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
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- 238000009903 catalytic hydrogenation reaction Methods 0.000 description 1
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- 125000006575 electron-withdrawing group Chemical group 0.000 description 1
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- 239000002638 heterogeneous catalyst Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- GBMDVOWEEQVZKZ-UHFFFAOYSA-N methanol;hydrate Chemical compound O.OC GBMDVOWEEQVZKZ-UHFFFAOYSA-N 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
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- 230000004048 modification Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 229920000927 poly(p-phenylene benzobisoxazole) Polymers 0.000 description 1
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 1
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- 238000011946 reduction process Methods 0.000 description 1
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- 238000001308 synthesis method Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- JRMUNVKIHCOMHV-UHFFFAOYSA-M tetrabutylammonium bromide Chemical compound [Br-].CCCC[N+](CCCC)(CCCC)CCCC JRMUNVKIHCOMHV-UHFFFAOYSA-M 0.000 description 1
- 238000001195 ultra high performance liquid chromatography Methods 0.000 description 1
- 238000004704 ultra performance liquid chromatography Methods 0.000 description 1
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Images
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- 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
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/56—Platinum group metals
- B01J23/62—Platinum group metals with gallium, indium, thallium, germanium, tin or lead
-
- 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
- B01J37/0201—Impregnation
- B01J37/0213—Preparation of the impregnating solution
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D213/00—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members
- C07D213/02—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members
- C07D213/04—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom
- C07D213/60—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D213/72—Nitrogen atoms
- C07D213/73—Unsubstituted amino or imino radicals
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
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- Chemical Kinetics & Catalysis (AREA)
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention provides a Pd-In intermetallic compound catalyst and a preparation method and application thereof, wherein the catalyst takes Pd as an active component and In as an auxiliary agent, a carrier is selected from carbon materials, alumina and silicon dioxide, a metal precursor solution is fully mixed with the carrier to obtain a mixture through impregnation, and the mixture is aged, dried and subjected to reduction atmosphere thermal reduction to obtain a crystal form of Pd 3 In, pdIn or Pd 2 In 3 A Pd-In intermetallic compound catalyst; the catalyst has high activity, high selectivity of 2,3,5,6-tetraaminopyridine, good stability, reusability and long service life, and is used for preparing 2,3,5,6-tetraaminopyridine by selective hydrogenation of 2,6-diamino-3,5-dinitropyridineThe reaction process of the pyridine has mild conditions, avoids the excessive hydrogenation of 2,3,5,6-tetraaminopyridine under the high-temperature condition, and has wide industrial application prospect.
Description
Technical Field
The invention belongs to the technical field of catalysts, and particularly relates to a Pd-In intermetallic compound catalyst and a preparation method and application thereof.
Background
High performance fibers are a new generation of synthetic fibers with unique properties developed by the fiber science and engineering industries, and the development of the high performance fibers is driven by specific application requirements to meet different application scenes, so that the high performance fibers occupy a place in the field of synthetic fibers. The well-known sensitivity of poly (p-Phenylene Benzobisoxazole) (PBO) fiber which is known as super fiber in the 21 st century to sunlight, particularly Ultraviolet (UV), causes the degradation of the structure and performance of the PBO fiber and the composite material thereof, and seriously affects the use safety and reliability of the PBO fiber composite material. The poly [2,5-dihydroxy-1,4-phenylenepyridobisimidazole ] fiber (PIPD fiber) developed by the Sikkema team of Akzo Nobel of the Netherlands solves the shortage of PBO in compressive strength, has excellent mechanical properties, stability and adhesiveness, and is the most comprehensive and excellent fiber at present. However, PIPD fibers have not been commercially applied to a large scale to date, primarily because the synthesis of PIPD monomers is experimentally challenging, especially the synthesis of 2,3,5,6-Tetraaminopyridine (TAP) monomers.
The TAP synthesis method is mainly a nitro catalytic reduction method, namely, the PIPD monomer (TAP) is synthesized by selectively hydrogenating 2,6-diamino-3,5-dinitropyridine (DADNP), wherein the commonly used reducing agents comprise anhydrous ammonium formate, divalent iron halide salt, divalent tin halide salt and the like. In recent years, with the development and progress of heterogeneous catalyst research, pd-based catalysts have received attention in the catalytic hydrogenation of 2,6-diamino-3,5-dinitropyridine (DADNP). However, the supported single-metal Pd catalyst has a strong adsorption capacity to the product 2,3,5,6-Tetraaminopyridine (TAP), and is prone to over-hydrogenation, resulting in low selectivity, and the supported single-Pd catalyst also has a problem of poor stability, which is not conducive to the industrial production of TAP.
In view of the above, it is very important to develop a new high-efficiency Pd-based catalyst to overcome the above problems in the prior art.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides an intermetallic compound catalyst for selectively hydrogenating 2,6-diamino-3,5-dinitropyridine to prepare 2,3,5,6-tetraaminopyridine, which has the advantages of mild reaction conditions, good catalytic activity, high reactant conversion rate, high product selectivity and long service life, and a preparation method and application thereof.
The first object of the present invention is to provide a palladium-indium intermetallic compound catalyst, which comprises an active component, an auxiliary agent and a carrier, wherein the active component is Pd element, the auxiliary agent is In element, and the carrier is selected from one of carbon material, alumina and silica; the active component and the auxiliary agent are intermetallic compounds, namely Pd-In intermetallic compounds are formed, and the Pd-In intermetallic compounds are Pd 3 In, pdIn or Pd 2 In 3 。
The load capacity of the active component Pd is 1wt% -30 wt%; preferably, the loading amount of the active component Pd is 1-10 wt%; more preferably, the loading amount of the active component Pd is 5wt%.
Further, the molar ratio of the auxiliary agent In to the active component Pd is 1: (0.6-5); preferably, the molar ratio of In to the active component Pd is 1: (0.8-4).
The second objective of the present invention is to provide a preparation method of a palladium-indium intermetallic compound catalyst, which is used for preparing intermetallic compound catalysts with different Pd/In ratios, and has the characteristics of high catalyst activity, high 2,3,5,6-tetraaminopyridine selectivity, and long service life, wherein the preparation method comprises the following steps:
(1) Taking metal salts of Pd and In as metal precursors, mixing the metal salts with a solvent to prepare a mixed metal salt solution, fully mixing the mixed metal salt solution with a carrier, preparing a mixture by adopting an impregnation method, and aging and drying the mixture to obtain the Pd-In/carrier material.
(2) And (2) carrying out reduction by the Pd-In/carrier material In the step (1) through reducing atmosphere heat to obtain the Pd-In intermetallic compound catalyst.
Further, in the step (1), the metal salt of Pd is selected from one of palladium sodium chlorate, palladium chloride and palladium nitrate dihydrate; preferably, the metal salt of Pd is palladium sodium chlorate. The metal salt of In is selected from one of indium nitrate pentahydrate, indium dichloride and indium trichloride; preferably, the metal salt of In is indium nitrate pentahydrate.
Further, in the mixed metal salt solution of step (1), the molar ratio of In ions to Pd ions is: 1: (0.6-5); preferably, the molar ratio of In and Pd ions is 1: (0.8-4).
Further, the solvent in the step (1) is selected from one or more of water, methanol, ethanol, acetone and acetonitrile; preferably, the solvent is water.
Further, the carrier in the step (1) is selected from one of carbon nano tube, activated carbon, carbon black, nano carbon fiber, alumina and silica; preferably, the support is a carbon nanotube.
Further, the mass ratio of the carrier to the mixed metal salt solution in the step (1) is 1: (1-3); preferably, the mass ratio of the carrier to the mixed metal salt solution is 1:1.
further, in the step (1), the aging condition is 6-12 hours at room temperature; preferably, it is aged at room temperature for 12 hours.
Further, in the step (1), the drying condition is drying for 6-12 hours at 80-140 ℃; preferably drying for 6 to 12 hours at a temperature of between 80 and 120 ℃; more preferably at 120 ℃ for 12 hours.
Further, in the step (2), the thermal reduction temperature is 300 to 700 ℃, and the reduction time is 2 to 10 hours, preferably 2 to 8 hours, and more preferably 4 hours.
The thermal reduction temperature is based on H 2 -difference in peak position of TPR in the range of 300 to 700 ℃ and reduction reactionThe reaction time may be appropriately adjusted within 2 to 10 hours depending on the selection of the reduction temperature, and the reaction time may be appropriately prolonged.
Preferably, the thermal reduction temperature is 400-600 ℃; more preferably, the thermal reduction temperature is 500 ℃.
Further, the reducing atmosphere is pure hydrogen or a mixture of hydrogen and an inert gas, and the volume ratio of hydrogen in the mixture is not less than 5%, preferably not less than 10%, and more preferably 20%, that is, the reducing atmosphere is a 20% hydrogen and 80% inert gas atmosphere; the inert gas is argon or nitrogen, preferably argon.
The third purpose of the invention is to provide the application of the palladium-indium intermetallic compound catalyst in the preparation of 2,3,5,6-tetraaminopyridine by selectively hydrogenating 2,6-diamino-3,5-dinitropyridine.
Furthermore, the reaction temperature of the 2,6-diamino-3,5-dinitropyridine selective hydrogenation preparation 2,3,5,6-tetraaminopyridine is 35-75 ℃, and the hydrogen pressure is 0.25-1.5 MPa.
Compared with the prior art, the invention has the beneficial effects that:
(1) The invention provides a controllable preparation method of a Pd-In intermetallic compound catalyst with an ordered and stable structure, which takes a carbon material, silicon dioxide or alumina as a carrier, and prepares different Pd-In/carrier materials by regulating the proportion of an active component Pd and an auxiliary agent In by using a conventional impregnation method; and the subsequent thermal reduction process is combined to realize the controllable preparation of different Pd-In intermetallic compounds. The geometric isolation and the electronic action between metal Pd and In can regulate and control the adsorption strength of various species In the reaction process, and further can regulate the product selectivity.
Found by the DFT calculation: compared with Pd, the adsorption of the reactant DADNP on the three Pd-In intermetallic compounds is obviously enhanced, and the adsorption of the reaction product TAP on the three Pd-In intermetallic compounds is obviously weakened. For example, TAP has about a 50% reduction in adsorption strength on the PdIn (110) plane compared to the Pd (111) plane, which is caused by the different electronic properties of the amino group and the nitro group, as an electron withdrawing group, is more readily adsorbed at electron-rich sites and the amino group is the opposite. After the intermetallic compound is formed, in has an electron donating effect on Pd, so that the electron density of Pd on the PdIn (110) surface is increased, the nitro adsorption is enhanced, and the amino adsorption is weakened.
(2) Compared with the traditional Pd-based catalyst, the supported Pd-In intermetallic compound catalyst changes the geometric structure and the electronic effect of the catalyst due to the introduction of In. Supported Pd 3 In, pdIn and Pd 2 In 3 The intermetallic compound catalyst has the characteristics of high catalytic activity, good selectivity and long service life, so that 2,6-diamino-3,5-dinitropyridine can achieve complete conversion in a relatively low temperature range, and the condition of excessive hydrogenation of 2,3,5,6-tetraaminopyridine under the high-temperature condition is avoided.
In conclusion, the catalyst has the advantages of simple preparation method, easy operation, low production cost, good stability, recoverability and repeated use; the catalyst is used for selectively hydrogenating 2,6-diamino-3,5-dinitropyridine to prepare 2,3,5,6-tetraaminopyridine, and the reaction process has mild conditions, is environment-friendly and has wide industrial application prospect.
Drawings
Fig. 1 is an HRTEM image of PdIn intermetallic compound in example 1.
Fig. 2 is an XRD diffractogram of PdIn intermetallic compound in example 1.
Fig. 3 is an XPS spectrum of PdIn intermetallic compound Pd 3d in example 1.
Fig. 4 is an XPS spectrum of PdIn intermetallic compound In 3d In example 1.
FIG. 5 shows Pd in example 2 3 HRTEM image of In intermetallic compound.
FIG. 6 shows Pd in example 2 3 XRD diffractogram of In intermetallic compound.
FIG. 7 shows Pd in example 2 3 XPS spectrum of In intermetallic compound Pd 3 d.
FIG. 8 shows Pd in example 2 3 XPS spectrum of In intermetallic compound In 3 d.
FIG. 9 shows Pd in example 3 2 In 3 HRTEM of intermetallic compoundsAnd (4) an image.
FIG. 10 shows Pd in example 3 2 In 3 XRD diffractogram of intermetallic compound.
FIG. 11 shows Pd in example 3 2 In 3 XPS spectrum of intermetallic compound Pd 3 d.
FIG. 12 shows Pd in example 3 2 In 3 XPS spectrum of intermetallic compound In 3 d.
Detailed Description
The present invention will be described in further detail with reference to examples. It is to be understood that the following examples are for illustrative purposes only and are not to be construed as limiting the scope of the present invention, and that certain insubstantial modifications and adaptations of the invention may be made by those skilled in the art based on the teachings herein.
As used herein, "room temperature" means 10-30 deg.C, preferably 20-25 deg.C.
Example 1
Weighing 0.1383g of palladium sodium chlorate and 0.1413g of indium nitrate pentahydrate, and performing ultrasonic dissolution In 1mL of ultrapure water to obtain a Pd-In metal salt solution; 1g of carbon nanotube was added to a Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier and the solution. And aging the impregnated catalyst precursor for 12 hours at room temperature, and drying in an oven at 120 ℃ for 12 hours.
At 20% of H 2 In the reducing atmosphere of/Ar, the mixture is reduced for 4 hours at the temperature of 400 ℃, and the heating rate is 10 ℃/min.
HRTEM characterization of the catalyst prepared in this example was performed, and as shown in FIG. 1, HRTEM images were used to observe the lattice fringes of the catalyst, and lattice measurements were performed by Digital micrographs; the lattice fringes of the exposed surface of the catalyst are 0.229nm, and the lattice fringes can be assigned to the (110) interplanar spacing of the intermetallic compound PdIn by comparing with XRD standard diffraction card (JCPDS 65-4805); in order to further determine the intermetallic compound structure of the Pd — In catalyst, XRD characterization was performed on the catalyst, as shown In fig. 2, the crystallinity of PdIn/CNT was very good, the peak shape was sharp, and the diffraction peaks at 39.16 °, 56.59 ° and 70.98 ° were assigned to PdIn (110), (200) and (211) crystal planes. The crystal form of the catalyst prepared by the embodiment is PdIn intermetallic compound.
The Pd 3d XPS graph and In 3d XPS of PdIn/CNT prepared In this example are shown In fig. 3 and 4, respectively, and the electron donating effect of In on Pd results In an increase In Pd electron density.
Example 2
Weighing 0.1383g of palladium sodium chlorate and 0.047g of indium nitrate pentahydrate, and carrying out ultrasonic dissolution In 1mL of ultrapure water to obtain a Pd-In metal salt solution; 1g of carbon nanotube was added to the Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier with the solution. And aging the impregnated catalyst precursor for 12 hours at room temperature, and drying in an oven at 120 ℃ for 12 hours.
At 20% of H 2 In the reducing atmosphere of/Ar, the mixture is reduced for 4 hours at the temperature of 400 ℃, and the heating rate is 10 ℃/min.
HRTEM and XRD characterization are carried out on the catalyst prepared in the embodiment, and the crystal form of the catalyst is Pd 3 An In intermetallic compound. As shown in FIG. 5, the lattice fringes of the exposed surface of the catalyst were 0.227nm, which is ascribed to the intermetallic compound Pd as compared to the XRD standard diffraction card (JCPDS 97-005-9476) 3 (111) interplanar spacing of In; as shown in FIG. 6, pd 3 In/CNT was matched to standard card, and the diffraction peak at 39.25 ℃ was assigned as Pd 3 In (111) crystal face, pd can be proved 3 Formation of In intermetallic compound.
Catalyst Pd prepared in this example 3 Pd 3d XPS and In 3d XPS of In/CNT are shown In FIGS. 7 and 8, respectively, and the electron donating effect of In on Pd results In an increase In Pd electron density.
Example 3
Weighing 0.1383g of palladium sodium chlorate and 0.2120g of indium nitrate pentahydrate, and performing ultrasonic dissolution In 1mL of ultrapure water to obtain a Pd-In metal salt solution; 1g of carbon nanotube was added to a Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier and the solution. And aging the impregnated catalyst precursor for 12 hours at room temperature, and drying in an oven at 120 ℃ for 12 hours.
At 20% of H 2 In a reducing atmosphere of/Ar at a temperature of 400 DEG CThe reduction is carried out for 4 hours, and the heating rate is 10 ℃/min.
HRTEM and XRD characterization are carried out on the catalyst prepared in the embodiment, and the crystal form of the catalyst is Pd 2 In 3 An intermetallic compound. As shown in FIG. 9, the lattice fringes of the exposed surface of the catalyst were 0.225nm, which is ascribed to the intermetallic compound Pd as compared to the XRD standard diffraction card (JCPDS 65-7212) 2 In 3 (110) interplanar spacing of (iii); as shown in FIG. 10, after reduction treatment, pd 2 In 3 the/CNT exposes a plurality of characteristic diffraction peaks, and the diffraction peaks of 27.31 degrees, 38.80 degrees, 39.28 degrees, 56.41 degrees and 70.56 degrees are respectively assigned as Pd in comparison with a standard card 2 In 3 (011) The crystal planes of (110), (012), (202) and (122) can prove Pd 2 In 3 Formation of intermetallic compounds.
Catalyst Pd prepared in this example 2 In 3 Pd 3d XPS and In 3d XPS of/CNT are shown In FIGS. 11 and 12, respectively, and the electron donating effect of In on Pd results In an increase In Pd electron density.
Example 4
Weighing 0.084g of palladium chloride and 0.1413g of indium nitrate pentahydrate, and carrying out ultrasonic dissolution In 1mL of ultrapure water to obtain a Pd-In metal salt solution; 1g of carbon nanotube was added to the Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier with the solution. And aging the impregnated catalyst precursor for 12 hours at room temperature, and drying in an oven at 120 ℃ for 12 hours.
At 20% of H 2 And in the reducing atmosphere of/Ar, reducing for 4 hours at the temperature of 400 ℃, wherein the heating rate is 10 ℃/min, and obtaining the PdIn/CNT catalyst.
Example 5
Weighing 0.1083g of palladium nitrate dihydrate and 3242 g of 0.1413g of indium nitrate pentahydrate, and carrying out ultrasonic dissolution In 1mL of ultrapure water to obtain a Pd-In metal salt solution; 1g of carbon nanotube was added to a Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier and the solution. And aging the impregnated catalyst precursor for 12 hours at room temperature, and drying in an oven at 120 ℃ for 12 hours.
At 20% of H 2 Reducing gas of/ArAnd reducing for 4 hours at the temperature of 400 ℃ in the atmosphere, wherein the heating rate is 10 ℃/min, and obtaining the PdIn/CNT catalyst.
Example 6
Weighing 0.1383g of palladium sodium chlorate and 0.0873g of indium dichloride, and performing ultrasonic dissolution In 1mL of ultrapure water to obtain a Pd-In metal salt solution; 1g of carbon nanotube was added to a Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier and the solution. And aging the impregnated catalyst precursor for 12 hours at room temperature, and drying in an oven at 120 ℃ for 12 hours.
At 20% of H 2 And in the reducing atmosphere of/Ar, reducing for 4 hours at the temperature of 400 ℃, wherein the heating rate is 10 ℃/min, and obtaining the PdIn/CNT catalyst.
Example 7
Weighing 0.1383g of palladium sodium chlorate and 0.1039g of indium trichloride, and carrying out ultrasonic dissolution In 1mL of ultrapure water to obtain a Pd-In metal salt solution; 1g of carbon nanotube was added to a Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier and the solution. And aging the impregnated catalyst precursor for 12 hours at room temperature, and drying in an oven at 120 ℃ for 12 hours.
At 20% of H 2 And in the reducing atmosphere of/Ar, reducing for 4 hours at the temperature of 400 ℃, wherein the heating rate is 10 ℃/min, and obtaining the PdIn/CNT catalyst.
Example 8
Weighing 0.1383g of palladium sodium chlorate and 0.047g of indium nitrate pentahydrate, and performing ultrasonic dissolution In 1mL of ethanol to obtain a Pd-In metal salt solution; 1g of carbon nanotube was added to the Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier with the solution. The impregnated catalyst precursor is aged for 12 hours at room temperature and then transferred into an oven at 120 ℃ for drying for 12 hours.
At 20% of H 2 In the reducing atmosphere of/Ar, reducing for 4 hours at the temperature of 400 ℃, wherein the heating rate is 10 ℃/min, and obtaining Pd 3 In/CNT catalyst.
Example 9
Weighing 0.1383g of palladium sodium chlorate and 0.047g of indium nitrate pentahydrate, and performing ultrasonic dissolution In 1mL of acetone to obtain a Pd-In metal salt solution; 1g of carbon nanotube was added to a Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier and the solution. And aging the impregnated catalyst precursor for 12 hours at room temperature, and drying in an oven at 120 ℃ for 12 hours.
At 20% of H 2 In the reducing atmosphere of/Ar, reducing for 4 hours at the temperature of 400 ℃, wherein the heating rate is 10 ℃/min, and obtaining Pd 3 In/CNT catalyst.
Example 10
Weighing 0.1383g of palladium sodium chlorate and 0.047g of indium nitrate pentahydrate, and carrying out ultrasonic dissolution In 1mL of ultrapure water to obtain a Pd-In metal salt solution; 1g of carbon nanotube was added to a Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier and the solution. And aging the impregnated catalyst precursor for 6 hours at room temperature, and drying in an oven at 120 ℃ for 12 hours.
At 20% of H 2 In the reducing atmosphere of/Ar, reducing for 4 hours at the temperature of 400 ℃, wherein the heating rate is 10 ℃/min, and obtaining Pd 3 In/CNT catalyst.
Example 11
Weighing 0.1383g of palladium sodium chlorate and 0.047g of indium nitrate pentahydrate, and carrying out ultrasonic dissolution In 1mL of ultrapure water to obtain a Pd-In metal salt solution; 1g of carbon nanotube was added to the Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier with the solution. And aging the impregnated catalyst precursor for 12 hours at room temperature, and drying in an oven at 80 ℃ for 12 hours.
At 20% of H 2 In the reducing atmosphere of/Ar, reducing for 4 hours at the temperature of 400 ℃, wherein the heating rate is 10 ℃/min, and obtaining Pd 3 An In/CNT catalyst.
Example 12
Weighing 0.1383g of palladium sodium chlorate and 0.047g of indium nitrate pentahydrate, and carrying out ultrasonic dissolution In 1mL of ultrapure water to obtain a Pd-In metal salt solution; 1g of carbon nanotube was added to a Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier and the solution. And aging the impregnated catalyst precursor for 12 hours at room temperature, and drying in an oven at 120 ℃ for 12 hours.
At 20% of H 2 In the reducing atmosphere of/Ar, reducing for 4 hours at the temperature of 500 ℃, wherein the heating rate is 10 ℃/min, and obtaining Pd 3 In/CNT catalyst.
Example 13
Weighing 0.1383g of palladium sodium chlorate and 0.047g of indium nitrate pentahydrate, and carrying out ultrasonic dissolution In 1mL of ultrapure water to obtain a Pd-In metal salt solution; 1g of carbon nanotube was added to the Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier with the solution. The impregnated catalyst precursor is aged for 12 hours at room temperature and then transferred into an oven at 120 ℃ for drying for 12 hours.
At 20% of H 2 In the reducing atmosphere of/Ar, reducing for 4 hours at the temperature of 600 ℃, wherein the heating rate is 10 ℃/min, and obtaining Pd 3 An In/CNT catalyst.
Example 14
Weighing 0.1383g of palladium sodium chlorate and 0.047g of indium nitrate pentahydrate, and carrying out ultrasonic dissolution In 1mL of ultrapure water to obtain a Pd-In metal salt solution; the 1g activated carbon tube was added to the Pd-In metal salt solution, and stirred with a glass rod to mix the carrier and the solution thoroughly. And aging the impregnated catalyst precursor for 12 hours at room temperature, and drying in an oven at 120 ℃ for 12 hours.
At 20% of H 2 In the reducing atmosphere of/Ar, reducing for 4 hours at the temperature of 400 ℃, wherein the heating rate is 10 ℃/min, and obtaining Pd 3 An In/AC catalyst.
Example 15
Weighing 0.1383g of palladium sodium chlorate and 0.047g of indium nitrate pentahydrate, and carrying out ultrasonic dissolution In 1mL of ultrapure water to obtain a Pd-In metal salt solution; 1g of the carbon nanofibers was added to the Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier and the solution. And aging the impregnated catalyst precursor for 12 hours at room temperature, and drying in an oven at 120 ℃ for 12 hours.
At 20% of H 2 In the reducing atmosphere of/Ar, reducing for 4 hours at the temperature of 400 ℃, wherein the heating rate is 10 ℃/min, and obtaining Pd 3 In/CNF catalyst.
Example 16
Weighing 0.1383g of palladium sodium chlorate and 0.047g of indium nitrate pentahydrate, and carrying out ultrasonic dissolution In 1mL of ultrapure water to obtain a Pd-In metal salt solution; 1g of carbon black was added to the Pd-In metal salt solution, and the carrier was thoroughly mixed with the solution by stirring with a glass rod. And aging the impregnated catalyst precursor for 12 hours at room temperature, and drying in an oven at 120 ℃ for 12 hours.
At 20% of H 2 In the reducing atmosphere of/Ar, reducing for 4 hours at the temperature of 400 ℃, wherein the heating rate is 10 ℃/min, and obtaining Pd 3 An In/CB catalyst.
Example 17
Weighing 0.1383g of palladium sodium chlorate and 0.047g of indium nitrate pentahydrate, and carrying out ultrasonic dissolution In 1mL of ultrapure water to obtain a Pd-In metal salt solution; 1g of alumina was added to the Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier with the solution. And aging the impregnated catalyst precursor for 12 hours at room temperature, and drying in an oven at 120 ℃ for 12 hours.
At 20% of H 2 In the reducing atmosphere of/Ar, reducing for 4 hours at the temperature of 400 ℃, wherein the heating rate is 10 ℃/min, and obtaining Pd 3 In/Al 2 O 3 A catalyst.
Example 18
Weighing 0.1383g of palladium sodium chlorate and 0.047g of indium nitrate pentahydrate, and carrying out ultrasonic dissolution In 1mL of ultrapure water to obtain a Pd-In metal salt solution; 1g of silica was added to a Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier with the solution. And aging the impregnated catalyst precursor for 12 hours at room temperature, and drying in an oven at 120 ℃ for 12 hours.
At 50% of H 2 In the reducing atmosphere of/Ar, reducing for 4 hours at the temperature of 400 ℃, wherein the heating rate is 10 ℃/min, and obtaining Pd 3 In/SiO 2 A catalyst.
Example 19
Weighing 0.1383g of palladium sodium chlorate and 0.047g of indium nitrate pentahydrate, and carrying out ultrasonic dissolution In 1mL of ultrapure water to obtain a Pd-In metal salt solution; 1g of carbon nanotube was added to a Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier and the solution. And aging the impregnated catalyst precursor for 12 hours at room temperature, and drying in an oven at 120 ℃ for 12 hours.
At 75% H 2 In the reducing atmosphere of/Ar, reducing for 4 hours at the temperature of 400 ℃, wherein the heating rate is 10 ℃/min, and obtaining Pd 3 In/CNT catalyst.
Example 20
Weighing 0.1383g of palladium sodium chlorate and 0.047g of indium nitrate pentahydrate, and carrying out ultrasonic dissolution In 1mL of ultrapure water to obtain a Pd-In metal salt solution; 1g of carbon nanotube was added to a Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier and the solution. And aging the impregnated catalyst precursor for 12 hours at room temperature, and drying in an oven at 120 ℃ for 12 hours.
At 100% H 2 In a reducing atmosphere of (2), reducing at 400 ℃ for 4 hours at a heating rate of 10 ℃/min to obtain Pd 3 In/CNT catalyst.
Example 21
Weighing 0.1383g of palladium sodium chlorate and 0.047g of indium nitrate pentahydrate, and carrying out ultrasonic dissolution In 2mL of ultrapure water to obtain a Pd-In metal salt solution; 1g of carbon nanotube was added to a Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier and the solution. And aging the impregnated catalyst precursor for 12 hours at room temperature, and drying in an oven at 120 ℃ for 12 hours.
At 20% of H 2 In the reducing atmosphere of/Ar, reducing for 4 hours at the temperature of 400 ℃, wherein the heating rate is 10 ℃/min, and obtaining Pd 3 In/CNT catalyst.
Example 22
Weighing 0.1383g of palladium sodium chlorate and 0.047g of indium nitrate pentahydrate, and carrying out ultrasonic dissolution In 3mL of ultrapure water to obtain a Pd-In metal salt solution; 1g of carbon nanotube was added to a Pd-In metal salt solution, and stirred with a glass rod to sufficiently mix the carrier and the solution. And aging the impregnated catalyst precursor for 12 hours at room temperature, and drying in an oven at 120 ℃ for 12 hours.
At 20% of H 2 Reduction is carried out in a reducing atmosphere of/Ar at a temperature of 400 ℃ for 4 hours at a rate of temperature riseAt 10 ℃/min, pd is obtained 3 In/CNT catalyst.
Example 23 evaluation of catalyst Performance
A methanol solution of DADNP was placed in a 1000mL volumetric flask as a reaction material at a concentration of 0.05mg/mL. 5mg of catalyst and 60mL of DADNP in methanol were added to the reaction vessel, which was closed and purged of air with argon for several times. The reaction is carried out at low temperature to reduce the formation of over-hydrogenated products. When the reaction temperature is stabilized to the set value, H 2 Filling into the reaction kettle, starting stirring and timing. The stirring rate was 800rpm, and after 240min of the reaction, a sample was taken and immediately analyzed by ultra high performance liquid chromatography.
It should be noted that the chromatograms used are: waters Acquity UPLC, chromatographic conditions column temperature: 25 ℃, flow rate: 0.4mL/min, mobile phase ratio: methanol Water (0.05M tetrabutylammonium Bromide, 0.025M NH) 4 H 2 PO 4 ) =40, detection wavelength: 237nm.
The same procedure as in example 1 was followed, except that indium nitrate pentahydrate was not added, to prepare a Pd/CNT catalyst. The catalytic performance of the catalyst of the invention for the selective hydrogenation of 2,6-diamino-3,5-dinitropyridine to 2,3,5,6-Tetraaminopyridine (TAP) was evaluated by testing 2,6-diamino-3,5-dinitropyridine (DADNP) conversion and 2,3,5,6-Tetraaminopyridine (TAP) selectivity and yield for the catalysts prepared in examples 1-22 and the Pd/CNT catalyst.
Wherein:
5363 selective hydrogenation of 2,6-diamino-3,5-dinitropyridine (DADNP) to 2,3,5,6-Tetraaminopyridine (TAP), the conversion of DADNP, the selectivity of TAP and the yield are calculated as follows:
X(％)＝(n initial DADNP -n Post-reaction DADNP )/n Initial DADNP ×100％
S i (％)＝(n Component i ×A i )/n Initial DADNP ×100％
Y i (％)＝X×S i ×100％
Wherein X represents the conversion rate of 2,6-diamino-3,5-dinitropyridine, and the unit is%;
n initial DADNP 、n Post-reaction DADNP Respectively representing the initial and reacted substance amounts of 2,6-diamino-3,5-dinitropyridine, and the unit is mol;
S i represents the selectivity of component i in%;
n component i Represents the amount of the substance of component i after the reaction in mol;
A i represents the number of carbon atoms contained in the molecule of component i;
Y i the yield of component i is expressed in%.
TABLE 1 evaluation results of selective hydrogenation reaction of DADNP In Pd-In catalyst
As can be seen from Table 1, three supported Pd-In intermetallic compound catalysts catalyze the DADNP hydrogenation reaction, the DADNP conversion is substantially complete; the TAP selectivity is more than 77 percent and is obviously superior to the Pd/CNT catalyst, and the TAP selectivity of the three Pd-In intermetallic compound catalysts is Pd In the high-low order 3 In>PdIn>Pd 2 In 3 ，Pd 3 The In/CNT catalyst has excellent activity and TAP selectivity, and the catalytic performance is the best.
Example 24 evaluation of catalyst stability
The PdIn/CNT catalyst prepared in example 1 and the Pd prepared in example 2 were randomly selected 3 In/CNT catalyst, pd prepared In example 3 2 In 3 Catalyst performance test method of example 23Methods, the stability of the catalysts were evaluated separately, and the results of the X (DADNP), S (TAP) and Y (TAP) data are shown in tables 2 to 4.
TABLE 2 PdIn/CNT catalyst stability evaluation
| Number of cycles | X(DADNP)(％) | S(TAP)(％) | Y(TAP)(％) |
| 1 | 100 | 85.13 | 85.13 |
| 2 | 100 | 85.10 | 85.10 |
| 3 | 100 | 85.08 | 85.08 |
| 5 | 100 | 84.95 | 84.95 |
| 10 | 99.40 | 84.87 | 84.36 |
As can be seen from Table 2, after the supported Pd-In intermetallic compound catalyst PdIn/CNT prepared In example 1 is subjected to evaluation of 10 cycles and each reaction time is 240min, the conversion rate of 2,6-diamino-3,5-dinitropyridine is still maintained to be more than 99.40%, the selectivity of 2,3,5,6-tetraaminopyridine is maintained to be more than 84.87%, and the yield of 2,3,5,6-tetraaminopyridine is maintained to be more than 84.36%.
The above results show that the supported Pd-In intermetallic compound catalyst PdIn/CNT prepared In example 1 has good stability.
TABLE 3 Pd 3 Evaluation of In/CNT catalyst stability
As can be seen from Table 3, the supported Pd-In intermetallic compound catalyst Pd prepared In example 2 3 In/CNT, after 10 cycles of evaluation, each reaction time of 240min, the conversion rate of 2,6-diamino-3,5-dinitropyridine is still maintained above 99.60%, the selectivity of 2,3,5,6-tetraaminopyridine is maintained above 88.07%, and the yield of 2,3,5,6-tetraaminopyridine is maintained above 87.72%.
The above results show that the supported Pd-In intermetallic compound catalyst PdIn/CNT prepared In example 2 has good stability.
TABLE 4 Pd 2 In 3 Evaluation of stability of/CNT catalyst
| Number of cycles | X(DADNP)(％) | S(TAP)(％) | Y(TAP)(％) |
| 1 | 100 | 80.09 | 80.09 |
| 2 | 100 | 80.05 | 80.05 |
| 3 | 100 | 80.02 | 80.02 |
| 5 | 100 | 79.88 | 79.88 |
| 10 | 99.20 | 79.72 | 79.08 |
As can be seen from Table 4, the supported Pd-In intermetallic compound catalyst Pd prepared In example 3 2 In 3 the/CNT, after 10 cycles and 240min evaluation of each reaction time, the conversion rate of 2,6-diamino-3,5-dinitropyridine is still maintained above 99.20%, the selectivity of 2,3,5,6-tetraaminopyridine is maintained above 79.72%, and the yield of 2,3,5,6-tetraaminopyridine is maintained above 79.08%.
The above results indicate that the supported Pd-In intermetallic compound catalyst PdIn/CNT prepared In example 3 has good stability.
In conclusion, the Pd-In intermetallic compound catalyst has good stability and long service life. The present application is described in detail for the purpose of enabling those skilled in the art to understand the content of the present application and to implement the same, and the scope of the present application is not limited thereto.
Claims (10)
1. The Pd-In intermetallic compound catalyst is characterized by comprising an active component, an auxiliary agent and a carrier, wherein the active component is Pd element, the auxiliary agent is In element, and the carrier is selected from one of carbon material, alumina and silicon dioxide; the active component and the auxiliary agent form Pd 3 In, pdIn or Pd 2 In 3 An intermetallic compound.
2. The Pd-In intermetallic compound catalyst according to claim 1, characterized In that the loading amount of the active component Pd is 1wt% to 30wt%; preferably 1wt% to 10wt%; more preferably 5wt%.
3. A method for preparing a Pd-In intermetallic compound catalyst is characterized by comprising the following steps:
(1) Taking metal salts of Pd and In as metal precursors, mixing the metal salts with a solvent to prepare a mixed metal salt solution, fully mixing the mixed metal salt solution with a carrier, preparing a mixture by adopting an impregnation method, and aging and drying the mixture to obtain the Pd-In/carrier material.
(2) And (2) carrying out reduction by the Pd-In/carrier material In the step (1) through reducing atmosphere heat to obtain the Pd-In intermetallic compound catalyst.
4. The method of preparing a Pd-In intermetallic compound catalyst according to claim 3, wherein the molar ratio of In to Pd ions In the mixed metal salt solution of step (1) is 1: (0.6-5); preferably 1: (0.8-4).
5. The method for preparing a Pd-In intermetallic compound catalyst according to claim 3, wherein In the step (1), the metal salt of Pd is selected from one of palladium sodium chlorate, palladium chloride and palladium nitrate dihydrate; the metal salt of In is selected from one of indium nitrate pentahydrate, indium dichloride and indium trichloride; the carrier is selected from one of carbon nano tube, activated carbon, carbon black, nano carbon fiber, alumina and silica; the solvent is selected from one or more of water, methanol, ethanol, acetone and acetonitrile.
6. The method for producing a Pd-In intermetallic compound catalyst according to claim 3, characterized In that the mass ratio of the support to the mixed metal salt solution In the step (1) is 1: (1-3); preferably 1:1.
7. the method for preparing a Pd-In intermetallic compound catalyst according to claim 3, characterized In that In the step (1), the aging condition is 6 to 12 hours at room temperature; the drying condition is that the mixture is dried for 6 to 12 hours at a temperature of between 80 and 140 ℃.
8. The method for preparing a Pd-In intermetallic compound catalyst according to claim 3, characterized In that, in the step (2), the thermal reduction temperature is 300 to 700 ℃, preferably 400 to 600 ℃, more preferably 500 ℃; the reduction time is 2 to 10 hours, preferably 2 to 8 hours, and more preferably 4 hours.
9. The method for producing a Pd-In intermetallic compound catalyst according to claim 3, characterized In that In step (2), the reducing atmosphere is pure hydrogen or a mixture of hydrogen and an inert gas, and the volume ratio of hydrogen In the mixture is not less than 5%, preferably not less than 10%, more preferably 20%, that is, the reducing atmosphere is 20% hydrogen and 80% inert gas atmosphere.
10. Use of the catalyst of any of claims 1-2 in a reaction to produce 2,3,5,6-tetraaminopyridine by selective hydrogenation of 2,6-diamino-3,5-dinitropyridine.
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