CN116851004B - Catalyst for high-efficiency low-temperature catalytic methane oxidation and preparation method and application thereof - Google Patents
Catalyst for high-efficiency low-temperature catalytic methane oxidation and preparation method and application thereof Download PDFInfo
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 68
- 239000003054 catalyst Substances 0.000 title claims abstract description 41
- 238000007254 oxidation reaction Methods 0.000 title claims abstract description 23
- 230000003647 oxidation Effects 0.000 title claims abstract description 22
- 238000002360 preparation method Methods 0.000 title claims abstract description 12
- 230000003197 catalytic effect Effects 0.000 title claims abstract description 11
- 238000005530 etching Methods 0.000 claims abstract description 23
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 23
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 17
- 239000011258 core-shell material Substances 0.000 claims abstract description 15
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 13
- 239000002923 metal particle Substances 0.000 claims abstract description 12
- 239000002243 precursor Substances 0.000 claims abstract description 12
- 239000002253 acid Substances 0.000 claims abstract description 8
- 238000001035 drying Methods 0.000 claims abstract description 6
- 238000000593 microemulsion method Methods 0.000 claims abstract description 5
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 5
- 238000002156 mixing Methods 0.000 claims abstract description 4
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 3
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 29
- 238000000034 method Methods 0.000 claims description 19
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 14
- 238000003756 stirring Methods 0.000 claims description 10
- 238000005406 washing Methods 0.000 claims description 10
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 claims description 7
- 239000008367 deionised water Substances 0.000 claims description 7
- 229910021641 deionized water Inorganic materials 0.000 claims description 7
- 229910052763 palladium Inorganic materials 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical compound C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 claims description 6
- 239000004530 micro-emulsion Substances 0.000 claims description 6
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 5
- 229910017604 nitric acid Inorganic materials 0.000 claims description 5
- QGLWBTPVKHMVHM-KTKRTIGZSA-N (z)-octadec-9-en-1-amine Chemical compound CCCCCCCC\C=C/CCCCCCCCN QGLWBTPVKHMVHM-KTKRTIGZSA-N 0.000 claims description 4
- BMGNSKKZFQMGDH-FDGPNNRMSA-L nickel(2+);(z)-4-oxopent-2-en-2-olate Chemical compound [Ni+2].C\C([O-])=C\C(C)=O.C\C([O-])=C\C(C)=O BMGNSKKZFQMGDH-FDGPNNRMSA-L 0.000 claims description 4
- JKDRQYIYVJVOPF-FDGPNNRMSA-L palladium(ii) acetylacetonate Chemical compound [Pd+2].C\C([O-])=C\C(C)=O.C\C([O-])=C\C(C)=O JKDRQYIYVJVOPF-FDGPNNRMSA-L 0.000 claims description 4
- 150000003839 salts Chemical class 0.000 claims description 4
- RMZAYIKUYWXQPB-UHFFFAOYSA-N trioctylphosphane Chemical compound CCCCCCCCP(CCCCCCCC)CCCCCCCC RMZAYIKUYWXQPB-UHFFFAOYSA-N 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 3
- 239000004312 hexamethylene tetramine Substances 0.000 claims description 3
- 235000010299 hexamethylene tetramine Nutrition 0.000 claims description 3
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 3
- 238000007873 sieving Methods 0.000 claims description 3
- LFQCEHFDDXELDD-UHFFFAOYSA-N tetramethyl orthosilicate Chemical compound CO[Si](OC)(OC)OC LFQCEHFDDXELDD-UHFFFAOYSA-N 0.000 claims description 3
- 238000005979 thermal decomposition reaction Methods 0.000 claims description 3
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 2
- 239000003995 emulsifying agent Substances 0.000 claims description 2
- 238000006243 chemical reaction Methods 0.000 abstract description 14
- 238000000197 pyrolysis Methods 0.000 abstract description 3
- 239000000243 solution Substances 0.000 description 17
- 230000008569 process Effects 0.000 description 10
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 9
- 229910052751 metal Inorganic materials 0.000 description 7
- 239000002184 metal Substances 0.000 description 7
- 239000002105 nanoparticle Substances 0.000 description 7
- 229910002669 PdNi Inorganic materials 0.000 description 6
- 229910052681 coesite Inorganic materials 0.000 description 5
- 229910052906 cristobalite Inorganic materials 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 229910052682 stishovite Inorganic materials 0.000 description 5
- 229910052905 tridymite Inorganic materials 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
- 241000023308 Acca Species 0.000 description 3
- 229910002492 Ce(NO3)3·6H2O Inorganic materials 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 230000009471 action Effects 0.000 description 3
- 239000000446 fuel Substances 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 239000012494 Quartz wool Substances 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
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- 238000011068 loading method Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
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- 150000004706 metal oxides Chemical class 0.000 description 1
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- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
- B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
- B01J23/8933—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/894—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with rare earths or actinides
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- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
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- B01D2255/1023—Palladium
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- B01D2255/2065—Cerium
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- B01D2255/20753—Nickel
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- B01D2257/7025—Methane
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Abstract
The invention relates to the field of catalysts, and discloses a catalyst for catalyzing methane oxidation at a high efficiency and low temperature, and a preparation method and application thereof, wherein the preparation method comprises the steps of (1) preparing palladium-nickel nano metal particles through high-temperature pyrolysis; (2) Preparing a core-shell structure with palladium-nickel nano metal particles as cores and silicon dioxide as shells by a reverse microemulsion method; (3) Etching the core-shell structure obtained in the step (2) by using an acid solution; (4) Mixing with Ce carrier precursor solution, roasting and drying to obtain the target catalyst, wherein the catalyst prepared by the invention can reduce the conversion temperature of methane catalytic oxidation and ensure long-time catalytic activity.
Description
Technical Field
The invention relates to the field of catalysts, in particular to a catalyst for catalyzing methane oxidation at a high efficiency and low temperature, and a preparation method and application thereof.
Background
The environmental problems associated with the use of efficient conventional fossil energy are increasingly prominent. The proliferation of natural gas and shale gas recoverable reserves has led to global interest in using methane for automobiles, power plants, and even fuel cells (e.g., solid oxide fuel cells). However, the exponential growth of the methane market has led to a threat of greenhouse gases, since methane is a notorious greenhouse gas with global warming potential as much as 20 times that of carbon dioxide. To alleviate the climate crisis and the human carbon footprint, methane emissions must be suppressed and unburned methane converted before it is released to nature. Direct combustion is currently used in the natural gas industry and in Solid Oxide Fuel Cell (SOFC) systems to manage potential methane emissions, but high temperature combustion inevitably produces toxic byproducts, such as SOx, NOx, etc., which are detrimental to public health. Therefore, in order to achieve the aims of energy conservation and emission reduction, a methane oxidation catalyst with high performance, low ignition temperature and stable structure is urgently required to be designed.
Palladium (Pd) is considered to be the most catalytically active catalyst at low temperatures (less than 300 ℃) and low levels of methane, and its morphology and interaction with the catalyst support severely affect catalytic performance. Studies have demonstrated that Fayet et al indicate that Pd nanoclusters containing 25 atoms have the highest activation activity for methane as compared to other nanoclusters having fewer Pd atoms (Fayet P., et al J Chem Phys,1990,92,254-261). Studies have also demonstrated that Pd nanoparticles decompose into inactive single atoms at high temperatures, rapidly losing the activity of methane oxidation (Goodman e.d., et al nat Catal,2019,2,748-755). Thus, the preparation of a stable Pd catalyst is critical to achieving low temperature conversion of methane.
In the conventional preparation method, active Pd is deposited on the surface of a metal oxide carrier by a strong electrostatic adsorption or impregnation method. However, the Pd catalyst prepared by the method has good initial activity, but the problems of rapid sintering of active metal, deep oxidation of the active metal, irreversible loss of reaction surface area and the like caused by weak metal-carrier interaction (MSI) seriously affect the activity and stability of the catalyst.
Disclosure of Invention
Therefore, it is necessary to provide a catalyst for catalyzing methane oxidation at a high efficiency and low temperature, and a preparation method and application thereof, so as to solve the problems that the existing palladium catalyst for methane oxidation is easy to deactivate and has insufficient stability at the reaction temperature of methane oxidation.
In order to achieve the above object, the present invention provides a method for preparing a catalyst for high-efficiency low-temperature catalytic methane oxidation, comprising:
(1) Fully mixing metal precursors of palladium and nickel with a surfactant in a solvent, and then performing high-temperature pyrolysis to prepare palladium-nickel nano metal particles;
(2) Preparing a core-shell structure with palladium-nickel nano metal particles as cores and silicon dioxide as shells by using the palladium-nickel nano metal particles obtained in the step (1) through a reverse microemulsion method;
(3) Etching the core-shell structure obtained in the step (2) by using an acid solution;
(4) And (3) taking the soluble salt of Ce as a carrier precursor, preparing a carrier precursor solution, heating, stirring and mixing the product obtained by etching in the step (3) and the carrier precursor, centrifuging, pre-drying, roasting, washing, drying, tabletting and sieving to obtain the target catalyst.
In some embodiments, the molar ratio of palladium to nickel in step (1) is 1:5.
In some embodiments, in step (1), the metal precursors of palladium and nickel are palladium acetylacetonate and nickel acetylacetonate, respectively, the solvent is oleylamine, and the surfactant is trioctylphosphine.
In some embodiments, the specific process of step (1): palladium acetylacetonate and nickel acetylacetonate are heated and fully dissolved in oleylamine under the nitrogen atmosphere, trioctylphosphine is added, and then the solution is heated and subjected to high-temperature thermal decomposition to prepare palladium-nickel nano metal particles.
In some embodiments, in the step (2), the emulsifier CO-630 and ammonia water are stirred and dispersed into cyclohexane to prepare a microemulsion, the palladium-nickel nano metal particles obtained in the step (1) are dissolved in the cyclohexane, then added into the microemulsion, then methyl orthosilicate is added, stirring is carried out at room temperature, then ethanol solution is added to carry out demulsification, centrifugation and washing, thus obtaining the core-shell structure.
In some embodiments, the acid solution in step (3) is nitric acid, and the etching time of the acid solution is 2-20h.
In some embodiments, the soluble salt of Ce is Ce (NO 3)3·6H2 O, ce (NO 3)3·6H2 O and hexamethylenetetramine) dissolved in deionized water to form a carrier precursor solution.
In some embodiments, step (4) is passed through a 40-60 mesh screen to obtain the catalyst.
A catalyst for high-efficiency low-temperature catalytic methane oxidation prepared by the preparation method.
The catalyst for catalyzing methane oxidation at high efficiency and low temperature is applied to catalyzing methane oxidation.
The technical scheme has the following beneficial effects:
In the present invention,
In the invention, palladium-nickel nano metal particles are prepared by high-temperature pyrolysis, and PdNI 5@SiO2 with a core-shell structure is prepared by the same reverse microemulsion method, and then Pd and Ni activities can be exposed through an etching process, so that the prepared catalyst has higher catalytic activity, and then CeO 2 is matched for loading, so that the stability of the catalyst can be greatly improved, and the catalyst is ensured not to be deactivated in the long-time (at least 50 h) catalytic reaction process.
Description of the terms
It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the statement "comprising … …" or "comprising … …" does not exclude the presence of additional elements in a process, method, article, or terminal device that includes the element. Further, herein, "greater than," "less than," "exceeding," and the like are understood to not include the present number; "above", "below", "within" and the like are understood to include this number.
As used herein, "room temperature" and "normal temperature" refer to ambient temperatures ranging from about 10deg.C to about 40deg.C. In some embodiments, "room temperature" or "ambient temperature" refers to a temperature from about 20 ℃ to about 30 ℃; in other embodiments, "room temperature" or "ambient temperature" refers to a temperature from about 25 ℃ to about 30 ℃; in still other embodiments, "room temperature" or "normal temperature" refers to 10 ℃, 15 ℃, 20 ℃, 25 ℃, 30 ℃,35 ℃, 40 ℃, and the like.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
Drawings
Fig. 1 is a TEM photograph of PdNi 5@SiO2 core-shell structures after etching for different times.
In fig. 2, a is the reactivity of the catalyst formed by PdNi 5@SiO2 after various etching times; b is the reaction stability of Pd@CeO 2,PdNi5@CeO2 and PdNI ppm@CeO2 formed after 12 hours of etching at 350 ℃.
Detailed Description
In order to describe the technical content, constructional features, achieved objects and effects of the technical solution in detail, the following description is made in detail with reference to specific embodiments.
Example 1
A method for preparing a catalyst for catalyzing methane oxidation at a high efficiency and low temperature comprises the following steps
(1) Preparing PdNi alloy nano particles by a high-temperature thermal decomposition method: 0.1mmol of palladium acetylacetonate (Pd (acca) 2), 5mmol of nickel acetylacetonate (Ni (acca) 2) and 5mL of oleylamine are taken and placed in a 25mL three-necked flask with a reflux device, heated to 60 ℃ under nitrogen atmosphere, stirred for 5min until Pd (acca) 2 is sufficiently dissolved, then injected with 0.5mL of trioctylphosphine, the color of the solution rapidly changes to dark yellow, stirring is continued for 5min, then the solution is heated to 240 ℃ within 5min, and black particles are generated when the temperature reaches 190 ℃. Maintaining at 240 deg.c for 45min, and cooling naturally to room temperature. Adding 20mL of ethanol to precipitate the nanoparticles, centrifuging, removing the clear liquid, and dissolving the centrifuged black nanoparticles in 12.5mL of cyclohexane solution for later use. The nanoparticle obtained in this process was designated PdNi 5.
(2) Preparing a PdNI 5@SiO2 core-shell structure by a reverse microemulsion method: a microemulsion was prepared by taking 12.5mL cyclohexane, 4mL CO-630,0.5mL ammonia in a 100mL round bottom flask, and stirring in a sealed manner for 10 min. Then, 12.5mL of the cyclohexane solution of PdNI 5 nano-particles was added to the microemulsion, and 0.5mL of methyl orthosilicate was rapidly added thereto, and the mixture was stirred at room temperature for 1h. Adding ethanol solution to demulsify, centrifuging, and washing with ethanol twice for use.
(3) Nitric acid etching: and placing the PdNI 5@SiO2 core-shell structure nano particles in a 1M HNO 3 solution, continuously stirring, regulating the acid corrosion time to 0h,2h,4h,8h,12h,15h,18h and 20h, centrifuging, and washing the solution with deionized water until the solution is neutral to obtain the etched core-shell structure.
TEM pictures of the etched core-shell structure are shown in FIG. 1.
The etched core-shell structure was then dispersed in 100mL of deionized water.
(4) Weighing 2.6g Ce (NO 3)3·6H2 O and 5.2g hexamethylenetetramine) in a beaker, adding 40mL of deionized water for dissolution, dropwise adding the clear mixture into the aqueous solution in the step (3) until the dissolution is complete, heating to 75 ℃, stirring for 3h, centrifuging, washing with deionized water twice, washing with ethanol once, drying at 60 ℃ for 12h, placing in a muffle furnace, roasting at 500 ℃ for 2h, placing the prepared powder in a 5M NaOH solution, respectively stirring for 2h, centrifuging, washing with deionized water twice, washing with ethanol once, and placing the centrifugate in a60 ℃ oven for 12h, tabletting, sieving, and taking 40-60 meshes to obtain the target catalyst product.
Example 2
And (3) carrying out a reaction of catalyzing methane oxidation on the catalyst obtained after the step (4) is carried out for different etching time, wherein the reaction conditions are as follows: 1% ch 4,5％O2,94％N2, space velocity: 30000 L.h -1·g-1.
The specific process of the catalytic methane oxidation reaction is as follows: the experiment was carried out in a conventional fixed bed flow reactor (inner diameter 5 mm) at normal pressure, and a K-type thermocouple was placed in the middle of the reactor to monitor the reaction temperature. 100mg of fresh catalyst (40-60 mesh size) was filled in the center of a quartz tube, both upstream and downstream of the catalyst were plugged with quartz wool, and the quartz tube was placed in a tube furnace controlled by an automatic thermometer. The products were analyzed by gas chromatography equipped with a hydrogen Flame Ionization Detector (FID). The freshly prepared samples were placed in a flowing 5% o 2/N2 gas mixture and pre-treated at 200 ℃ for 2 hours prior to measurement. Then N 2 was introduced and rinsed for 0.5h. And a reaction gas containing 1.2vol% CH 4、6vol％O2 and N 2 was introduced at a total flow rate of 50mL×min -1 (gas hourly space velocity (GHSV) of 30000 mL. Gcat -1·h-1). Then gas chromatography data are collected at 200 ℃ to 850 ℃ at intervals of 50 ℃, and the data are collected after the catalyst is required to be stabilized at each temperature point for 15 min.
The catalytic reaction is shown in figure 2a, the temperatures (T 10,T50 and T 90) at 10%,50% and 90% methane conversion rate are 269 ℃,363 ℃ and 450 ℃ respectively, the T 10,T50 and T 90 of the formed catalyst gradually decrease along with the extension of etching time, and the catalytic activity reaches the optimum when the etching time is 12 hours, and the corresponding T 10,T50 and T 90 are 249 ℃,316 ℃ and 350 ℃ respectively. This means that the etching process preferentially removes Ni metal in the PdNi 5 alloy, leaving more Pd active as exposed. Further extension of the etching time, instead, the corresponding catalysts, T 10,T50 and T 90, increased, indicating that the long etching time would cause loss of metal Pd, resulting in a reduction in the number of active bits.
Comparative example 1
The difference from example 1 is that: ni precursor is not added during the synthesis of the metal nano particles, and then the Pd@CeO 2 is obtained without a nitric acid etching step.
Comparative example 2
The difference from example 1 is that: the PdNI 5@CeO2 is obtained without nitric acid etching.
And (3) carrying out a reaction for catalyzing methane oxidation on the catalyst-PdNI ppm@CeO2 obtained after the step (4) is carried out, wherein the etching time of the catalyst is 12h, namely, the comparative example 1-Pd@CeO 2, the comparative example 2-PdNI 5@CeO2 and the example 1 is carried out, and the reaction conditions are as follows: 1% ch 4,5％O2,94％N2, space velocity: 30000 L.h -1·g-1.
FIG. 2b shows the reaction stability of Pd@CeO 2,PdNi5@CeO2 and PdNi ppm@CeO2 formed after 12h of etching at 350 ℃. As can be seen from the figure, the stability of the single metal Pd@CeO 2 catalyst is poor, and obvious deactivation can be observed within 20 hours of reaction. And the stability of PdNI 5@CeO2 and PdNI ppm @CeO2 formed after 12 hours of etching is higher, and no deactivation is observed in the reaction process of 50 hours.
While the embodiments have been described above, other variations and modifications will occur to those skilled in the art once the basic inventive concepts are known, and it is therefore intended that the foregoing description and drawings illustrate only embodiments of the invention and not limit the scope of the invention, and it is therefore intended that the invention not be limited to the specific embodiments described, but that the invention may be practiced with their equivalent structures or with their equivalent processes or with their use directly or indirectly in other related fields.
Claims (4)
1. The preparation method of the catalyst for catalyzing methane oxidation at a high efficiency and low temperature is characterized by comprising the following steps:
(1) Palladium acetylacetonate and nickel acetylacetonate are heated under the nitrogen atmosphere to be fully dissolved into oleylamine, trioctylphosphine is added, and then the solution is heated and subjected to high-temperature thermal decomposition to prepare palladium-nickel nano metal particles;
(2) Preparing a core-shell structure with palladium-nickel nano metal particles as cores and silicon dioxide as shells by using the palladium-nickel nano metal particles obtained in the step (1) through a reverse microemulsion method;
(3) Etching the core-shell structure obtained in the step (2) by using an acid solution;
(4) Preparing carrier precursor solution by taking soluble salt of Ce as carrier precursor, heating, stirring and mixing the product obtained by etching in the step (3) and the carrier precursor, centrifuging, pre-drying, roasting, washing, drying, tabletting and sieving to obtain the target catalyst,
Stirring and dispersing an emulsifier CO-630 and ammonia water into cyclohexane to prepare microemulsion, dissolving palladium-nickel nano metal particles obtained in the step (1) into cyclohexane, adding the microemulsion, adding methyl orthosilicate, stirring at room temperature, adding an ethanol solution to demulsifie, centrifuging and washing to obtain the core-shell structure,
The soluble salt of Ce is Ce (NO 3)3•6H2 O, ce (NO 3)3•6H2 O and hexamethylenetetramine are dissolved in deionized water to form a carrier precursor solution,
The molar ratio of palladium to nickel in step (1) is 1:5,
The acid solution in the step (3) is 1M nitric acid, and the etching time of the acid solution is 12h.
2. The method according to claim 1, wherein the catalyst is obtained by passing the catalyst through a 40-60 mesh sieve in the step (4).
3. A catalyst for high efficiency low temperature catalytic methane oxidation prepared according to the preparation method of any one of claims 1 or 2.
4. Use of a catalyst for catalyzing methane oxidation at a high efficiency and low temperature prepared by the preparation method according to any one of claims 1 or 2 for catalyzing methane oxidation.
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| CN104174411A (en) * | 2014-07-07 | 2014-12-03 | 中国科学院过程工程研究所 | Method for improving catalytic oxidization activity of VOCs catalyst |
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| CN106799229A (en) * | 2017-01-22 | 2017-06-06 | 南昌大学 | A kind of core shell structure Pd Ce@SiO2Catalyst and preparation method |
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| CN106311273A (en) * | 2016-07-26 | 2017-01-11 | 厦门大学 | Ceria-laden PdNi alloy catalyst and the preparation method and application thereof |
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