CN112717971A - Carbon-based catalyst, preparation method and application thereof, and method for preparing styrene by ethylbenzene dehydrogenation - Google Patents
Carbon-based catalyst, preparation method and application thereof, and method for preparing styrene by ethylbenzene dehydrogenation Download PDFInfo
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- CN112717971A CN112717971A CN201910972208.2A CN201910972208A CN112717971A CN 112717971 A CN112717971 A CN 112717971A CN 201910972208 A CN201910972208 A CN 201910972208A CN 112717971 A CN112717971 A CN 112717971A
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- 239000003054 catalyst Substances 0.000 title claims abstract description 121
- YNQLUTRBYVCPMQ-UHFFFAOYSA-N Ethylbenzene Chemical compound CCC1=CC=CC=C1 YNQLUTRBYVCPMQ-UHFFFAOYSA-N 0.000 title claims abstract description 86
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 50
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 50
- 238000000034 method Methods 0.000 title claims abstract description 45
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 title claims abstract description 38
- 238000006356 dehydrogenation reaction Methods 0.000 title claims abstract description 31
- 238000002360 preparation method Methods 0.000 title claims abstract description 16
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 80
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 63
- 239000000725 suspension Substances 0.000 claims description 45
- 238000001354 calcination Methods 0.000 claims description 43
- 239000002113 nanodiamond Substances 0.000 claims description 42
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 41
- 229910052757 nitrogen Inorganic materials 0.000 claims description 41
- 239000011574 phosphorus Substances 0.000 claims description 41
- 229910052698 phosphorus Inorganic materials 0.000 claims description 41
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 30
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 claims description 28
- 239000012298 atmosphere Substances 0.000 claims description 28
- 239000008103 glucose Substances 0.000 claims description 28
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 22
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 claims description 20
- 239000001099 ammonium carbonate Substances 0.000 claims description 20
- 235000012501 ammonium carbonate Nutrition 0.000 claims description 20
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 claims description 20
- 229910000387 ammonium dihydrogen phosphate Inorganic materials 0.000 claims description 20
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 20
- 235000019837 monoammonium phosphate Nutrition 0.000 claims description 20
- 239000001301 oxygen Substances 0.000 claims description 20
- 229910052760 oxygen Inorganic materials 0.000 claims description 20
- 238000001035 drying Methods 0.000 claims description 19
- 150000001875 compounds Chemical class 0.000 claims description 17
- 238000002791 soaking Methods 0.000 claims description 17
- 239000002904 solvent Substances 0.000 claims description 15
- 239000002270 dispersing agent Substances 0.000 claims description 14
- 239000007789 gas Substances 0.000 claims description 13
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 12
- 229910052796 boron Inorganic materials 0.000 claims description 12
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 10
- 238000002156 mixing Methods 0.000 claims description 10
- 230000004048 modification Effects 0.000 claims description 9
- 238000012986 modification Methods 0.000 claims description 9
- 239000007800 oxidant agent Substances 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 8
- 230000001590 oxidative effect Effects 0.000 claims description 8
- 229910052786 argon Inorganic materials 0.000 claims description 5
- 239000004327 boric acid Substances 0.000 claims description 5
- 239000003085 diluting agent Substances 0.000 claims description 5
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical group [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 5
- MNNHAPBLZZVQHP-UHFFFAOYSA-N diammonium hydrogen phosphate Chemical compound [NH4+].[NH4+].OP([O-])([O-])=O MNNHAPBLZZVQHP-UHFFFAOYSA-N 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 4
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims description 3
- 239000001307 helium Substances 0.000 claims description 3
- 229910052734 helium Inorganic materials 0.000 claims description 3
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 3
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 claims description 3
- 239000003960 organic solvent Substances 0.000 claims description 3
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 2
- 239000004254 Ammonium phosphate Substances 0.000 claims description 2
- 239000002202 Polyethylene glycol Substances 0.000 claims description 2
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 2
- 229910000148 ammonium phosphate Inorganic materials 0.000 claims description 2
- 235000019289 ammonium phosphates Nutrition 0.000 claims description 2
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 claims description 2
- 229910052921 ammonium sulfate Inorganic materials 0.000 claims description 2
- 235000011130 ammonium sulphate Nutrition 0.000 claims description 2
- 229910021538 borax Inorganic materials 0.000 claims description 2
- 125000005619 boric acid group Chemical group 0.000 claims description 2
- 239000004202 carbamide Substances 0.000 claims description 2
- 235000013877 carbamide Nutrition 0.000 claims description 2
- 229910000388 diammonium phosphate Inorganic materials 0.000 claims description 2
- 235000019838 diammonium phosphate Nutrition 0.000 claims description 2
- UQGFMSUEHSUPRD-UHFFFAOYSA-N disodium;3,7-dioxido-2,4,6,8,9-pentaoxa-1,3,5,7-tetraborabicyclo[3.3.1]nonane Chemical compound [Na+].[Na+].O1B([O-])OB2OB([O-])OB1O2 UQGFMSUEHSUPRD-UHFFFAOYSA-N 0.000 claims description 2
- 239000011261 inert gas Substances 0.000 claims description 2
- 229910052754 neon Inorganic materials 0.000 claims description 2
- GKAOGPIIYCISHV-UHFFFAOYSA-N neon atom Chemical group [Ne] GKAOGPIIYCISHV-UHFFFAOYSA-N 0.000 claims description 2
- 229920001223 polyethylene glycol Polymers 0.000 claims description 2
- 239000004328 sodium tetraborate Substances 0.000 claims description 2
- 235000010339 sodium tetraborate Nutrition 0.000 claims description 2
- YWYZEGXAUVWDED-UHFFFAOYSA-N triammonium citrate Chemical compound [NH4+].[NH4+].[NH4+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O YWYZEGXAUVWDED-UHFFFAOYSA-N 0.000 claims description 2
- 238000007598 dipping method Methods 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 abstract description 18
- 239000000843 powder Substances 0.000 description 20
- 238000001179 sorption measurement Methods 0.000 description 19
- 239000000203 mixture Substances 0.000 description 17
- 239000012300 argon atmosphere Substances 0.000 description 16
- 238000009210 therapy by ultrasound Methods 0.000 description 16
- 238000004090 dissolution Methods 0.000 description 13
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 9
- 229910021392 nanocarbon Inorganic materials 0.000 description 9
- 238000003756 stirring Methods 0.000 description 9
- 239000003575 carbonaceous material Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 5
- 238000005839 oxidative dehydrogenation reaction Methods 0.000 description 5
- 229920006395 saturated elastomer Polymers 0.000 description 5
- 239000012495 reaction gas Substances 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 238000005265 energy consumption Methods 0.000 description 3
- 238000005470 impregnation Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- -1 oxygen deficiency Chemical compound 0.000 description 3
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 description 2
- 238000004438 BET method Methods 0.000 description 2
- KAKZBPTYRLMSJV-UHFFFAOYSA-N Butadiene Chemical compound C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 description 2
- 206010021143 Hypoxia Diseases 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 238000003917 TEM image Methods 0.000 description 2
- APNXFONTPPVBDA-UHFFFAOYSA-N [O].CCC1=CC=CC=C1 Chemical compound [O].CCC1=CC=CC=C1 APNXFONTPPVBDA-UHFFFAOYSA-N 0.000 description 2
- 239000002156 adsorbate Substances 0.000 description 2
- 150000001298 alcohols Chemical class 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 239000006012 monoammonium phosphate Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- ZSDSQXJSNMTJDA-UHFFFAOYSA-N trifluralin Chemical compound CCCN(CCC)C1=C([N+]([O-])=O)C=C(C(F)(F)F)C=C1[N+]([O-])=O ZSDSQXJSNMTJDA-UHFFFAOYSA-N 0.000 description 2
- 229910021642 ultra pure water Inorganic materials 0.000 description 2
- 239000012498 ultrapure water Substances 0.000 description 2
- 239000005696 Diammonium phosphate Substances 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 229920000122 acrylonitrile butadiene styrene Polymers 0.000 description 1
- 239000004480 active ingredient Substances 0.000 description 1
- 150000001335 aliphatic alkanes Chemical class 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 1
- 150000001735 carboxylic acids Chemical class 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229920005990 polystyrene resin Polymers 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
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- 238000001228 spectrum Methods 0.000 description 1
- 229920003051 synthetic elastomer Polymers 0.000 description 1
- 239000005061 synthetic rubber Substances 0.000 description 1
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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
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/24—Nitrogen compounds
-
- 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
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/20—Carbon compounds
- B01J27/22—Carbides
- B01J27/224—Silicon carbide
- B01J27/228—Silicon carbide with phosphorus, arsenic, antimony or bismuth
-
- 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
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/20—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state
- B01J35/23—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state in a colloidal state
-
- 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
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
- B01J35/61—Surface area
- B01J35/615—100-500 m2/g
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
- C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
- C07C5/327—Formation of non-aromatic carbon-to-carbon double bonds only
- C07C5/333—Catalytic processes
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2527/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- C07C2527/20—Carbon compounds
- C07C2527/22—Carbides
- C07C2527/224—Silicon carbide
- C07C2527/228—Silicon carbide with phosphorus, arsenic, antimony or bismuth
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2527/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- C07C2527/24—Nitrogen compounds
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Abstract
The invention relates to the field of catalyst preparation, and discloses a carbon-based catalyst, a preparation method and application thereof, and a method for preparing styrene by ethylbenzene dehydrogenation. The carbon-based catalyst provided by the invention is an integral catalyst, is convenient to transport, has a simple preparation method, does not need special equipment and complex operation steps, and can be used for producing styrene at a relatively low reaction temperature in the ethylbenzene dehydrogenation reaction process.
Description
Technical Field
The invention relates to the field of catalyst preparation, in particular to a carbon-based catalyst, a preparation method and application thereof, and a method for preparing styrene by ethylbenzene dehydrogenation.
Background
Styrene is an important organic raw material for producing products such as polystyrene resin, ABS resin, synthetic rubber and the like, and has very wide application. The dehydrogenation of ethylbenzene to styrene is the main route for preparing styrene industrially at present. At present, the reaction is carried out under the action of an iron-based catalyst, under the conditions of high temperature and excessive steam. The steam can provide energy required by the reaction in the production process of the styrene, play a role in reducing the ethylbenzene partial pressure and promoting the reaction to move in the forward direction, and also can automatically remove coke, prevent the active components of the catalyst from being reduced and the like. Therefore, a large amount of superheated steam is required to be consumed as a dehydrogenation medium in the styrene production process, and the consumption of a large amount of steam causes large energy consumption, large product condensation amount, high process equipment cost and high production cost. Under the situation that the global energy and environmental problems are increasingly prominent, the healthy development of the styrene industry is always puzzled by the problem of large energy consumption.
Compared with the direct dehydrogenation reaction, the oxidative dehydrogenation reaction of the ethylbenzene oxygen is an exothermic reaction, can be carried out at a lower temperature, saves energy, overcomes the limitation of thermodynamic equilibrium, and greatly simplifies the reaction process. However, the deep oxidation of the product and the difficult control of the product distribution can occur. If the ethylbenzene can react under the condition of a small amount of oxygen, namely oxygen deficiency, the energy consumption can be reduced, and the selectivity of the product can be ensured, so that the ethylbenzene oxygen deficiency dehydrogenation reaction becomes a new process route with potential competitiveness.
In recent years, nanocarbon materials have been widely studied for their stability and excellent catalytic activity. For example, CN105330502A (application of a heteroatom-modified nano-carbon material as a catalyst for oxidative dehydrogenation of n-butene) discloses that a heteroatom-modified nano-carbon material is used as a catalyst, the conversion rate of n-butene is 25-60%, and the selectivity of butadiene is 56-90%.
At present, the activity, selectivity and stability of the catalyst using the nanocarbon material are to be further improved.
Disclosure of Invention
The invention aims to solve the problems of poor activity, selectivity and stability of a nano carbon material catalyst in the prior art, and provides a carbon-based catalyst, a preparation method and application thereof, and a method for preparing styrene by ethylbenzene dehydrogenation.
The inventor of the invention finds that the nano carbon material is generally in powder shape, and if the nano carbon material can be compounded on a carrier to obtain the monolithic catalyst, the nano carbon material can fully disperse active components on the surface on one hand, and is helpful to avoid the pressure drop of a fixed bed reactor on the other hand, so that the competitiveness of the nano carbon material for the dehydrogenation reaction process is improved.
In order to achieve the above object, a first aspect of the present invention provides a carbon-based catalyst comprising a carrier and an active component supported on the carrier, wherein the active component comprises nanodiamond and a modifying element selected from at least one of nitrogen, phosphorus and boron.
Preferably, the carrier is silicon carbide, more preferably beta-SiC.
The second aspect of the present invention provides a method for preparing a carbon-based catalyst, comprising the steps of:
(1) mixing the nano-diamond, a compound containing modified elements, glucose, a dispersing agent and a solvent to obtain an active component suspension; the compound containing the modification element is selected from at least one of a nitrogen source, a boron source and a phosphorus source;
(2) and (2) soaking the carrier into the active component suspension liquid in the step (1), and sequentially drying, pre-calcining and calcining.
In a third aspect, the invention provides a carbon-based catalyst prepared by the above preparation method.
The fourth aspect of the invention provides the use of the carbon-based catalyst in ethylbenzene dehydrogenation.
In a fifth aspect, the present invention provides a method for preparing styrene by ethylbenzene dehydrogenation, the method comprising:
under the condition of ethylbenzene dehydrogenation reaction, the mixed gas containing ethylbenzene, diluent and oxidant is contacted with the above-mentioned carbon-based catalyst.
The technical scheme provided by the invention has the following advantages:
1. the carbon-based catalyst provided by the invention is an integral catalyst, and is convenient to transport.
2. The carbon-based catalyst provided by the invention can be used in the ethylbenzene dehydrogenation reaction process and can be carried out at a relatively low reaction temperature.
3. The preparation method of the carbon-based catalyst provided by the invention is simple, and does not need special equipment and complex operation steps;
4. when the reaction temperature is 450 ℃, the catalyst dosage is 150mg, the total reaction gas flow is 30ml/min, and the molar ratio of ethylbenzene to oxygen is 1:1, the conversion rate can reach 33.9 percent at most and the selectivity can reach 92.9 percent at most after stable operation for 50 hours, thereby obtaining better technical effects.
Drawings
FIG. 1 is an SEM photograph of a carbon-based catalyst obtained in example 1 of the present invention;
FIG. 2 is a TEM image of a carbon-based catalyst obtained in example 1 of the present invention;
fig. 3 is an XRD pattern of the carbon-based catalyst obtained in example 1 of the present invention.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
In the present invention, the carbon-based catalyst refers to a catalyst in which an active component of the catalyst contains carbon element.
The invention provides a carbon-based catalyst, which comprises a carrier and an active component loaded on the carrier, wherein the active component comprises nano diamond and a modification element, and the modification element is at least one selected from nitrogen element, phosphorus element and boron element.
According to the invention, preferably, the support is silicon carbide, preferably β -SiC. When the beta-SiC carrier is adopted, the catalyst formed by the active component and the carrier has better selectivity and stability in the ethylbenzene dehydrogenation reaction process.
According to the invention, the content of the modifying element is preferably from 0.5 to 45% by weight, more preferably from 20 to 38% by weight, based on the total amount of the active components.
According to the present invention, the modifying element may be one, two or three of nitrogen, phosphorus and boron.
According to a preferred embodiment of the present invention, the modifying element comprises nitrogen and/or phosphorus, more preferably nitrogen and phosphorus, and further preferably the mass ratio of nitrogen to phosphorus is (1-40): 1, more preferably (3-33): 1. the adoption of the preferred embodiment is more beneficial to further improving the selectivity and the stability of the carbon-based catalyst in the ethylbenzene dehydrogenation reaction process.
According to the present invention, preferably, the carbon-based catalyst has a specific surface area of 50 to 240m2(ii)/g, more preferably 110-2(ii) in terms of/g. The specific surface area of the catalyst can be measured by using a Tristar 3000 type physical adsorption apparatus from Micromeritics, USAN2As adsorbates, the samples were subjected to vacuum pretreatment at 300 ℃ and the BET method was used to calculate the specific surface area of the catalyst samples.
According to the present invention, preferably, the particle size of the active component is 1 to 10 nm. In the present invention, the particle size of the active ingredient is measured using a FEI Tecnai G2F 20S-TWIN transmission electron microscope in the United states, unless otherwise specified.
The content of the active component in the carbon-based catalyst is selected in a wide range, and preferably, the content of the active component is 20-60 wt% based on the total amount of the carbon-based catalyst; the content of the carrier is 40-80 wt%; further preferably, the content of the active component is 35-50 wt% and the content of the carrier is 50-65 wt% based on the total amount of the carbon-based catalyst. The preferred embodiment is more beneficial to further improving the activity, selectivity and stability of the carbon-based catalyst in ethylbenzene dehydrogenation.
The second aspect of the present invention provides a method for preparing a carbon-based catalyst, comprising the steps of:
(1) mixing the nano-diamond, a compound containing modified elements, glucose, a dispersing agent and a solvent to obtain an active component suspension; the compound containing the modification element is selected from at least one of a nitrogen source, a boron source and a phosphorus source;
(2) and (2) soaking the carrier into the active component suspension liquid in the step (1), and sequentially drying, pre-calcining and calcining.
In the mixing process of the nano-diamond, the compound containing the modifying element, the glucose, the dispersant and the solvent in the step (1), the adding sequence of the materials is not particularly limited, the nano-diamond, the compound containing the modifying element, the glucose, the dispersant and the solvent can be added together, or after mixing two of the components, the other rest components can be sequentially added. In order to enhance the mixing uniformity, glucose and a dispersant can be dissolved in a solvent, then a compound containing a modification element is added, and finally the nano-diamond is added.
According to the invention, preferably, the mixing in step (1) is carried out under ultrasonic conditions for 10-200min, preferably 20-60 min.
In the present invention, the mixing temperature is not particularly limited, and may be, for example, from room temperature to 80 ℃ and, for energy saving and ease of operation, it is preferable that the mixing is carried out at room temperature (20 to 30 ℃).
According to the present invention, preferably, the solvent is water and/or an organic solvent. The water can be distilled water, deionized water or ultrapure water, and is further preferably ultrapure water; the organic solvent is not particularly limited in the present invention, and may be conventionally selected in the art, and examples thereof include alkanes, alcohols, esters, and carboxylic acids, more preferably alcohols, still more preferably methanol and/or ethanol, and particularly preferably ethanol.
According to the present invention, the amount of the solvent is selected from a wide range, and can be determined by those skilled in the art according to the content of the active component in the target catalyst and the water absorption of the carrier.
The invention has wide selection range of the dispersant as long as the aim of dispersing powder can be achieved. Preferably, the dispersant is selected from at least one of citric acid, ammonium citrate and polyethylene glycol, and further preferably citric acid.
According to the preparation method of the carbon-based catalyst provided by the invention, preferably, the mass ratio of the dispersing agent to the nano-diamond is 0.5-2: 1, preferably 1 to 1.5: 1.
according to the invention, preferably, the mass ratio of glucose to nanodiamond is 0.5-1.5: 1, preferably 0.8 to 1.2: 1.
according to the present invention, the nitrogen source may be a nitrogen-containing compound soluble in the solvent or soluble in the solvent by a dispersant and/or glucose, and preferably, the nitrogen source is selected from at least one of ammonium carbonate, ammonium sulfate, urea and aqueous ammonia, and more preferably ammonium carbonate.
According to the invention, the boron source may be a boron-containing compound soluble in the solvent or soluble in the solvent under the action of a dispersant and/or glucose, preferably the boron source is selected from boric acid and/or sodium tetraborate, more preferably boric acid.
According to the present invention, the phosphorus source may be a phosphorus-containing compound that is soluble in the solvent or soluble in the solvent by the action of a dispersant and/or glucose, preferably, the phosphorus source is selected from at least one of monoammonium phosphate, diammonium phosphate, and ammonium phosphate, and more preferably, monoammonium phosphate.
According to a preferred embodiment of the present invention, the compound containing the modifying element is a nitrogen source and/or a phosphorus source, more preferably a nitrogen source and a phosphorus source, and particularly preferably, the nitrogen source and the phosphorus source are used in a mass ratio of (1-40): 1, preferably (3-33): 1.
according to the present invention, the amount of the nanodiamond and the compound containing the modifying element is preferably such that the content of the modifying element in the resulting catalyst is 0.5 to 45% by weight, more preferably 20 to 38% by weight, based on the total amount of the nanodiamond and the modifying element.
According to a preferred embodiment of the present invention, the amounts of the nanodiamond, the compound containing the modifying element and the carrier are such that the resulting catalyst contains 20 to 60 wt.%, more preferably 35 to 50 wt.%, of the nanodiamond and the modifying element, based on the total amount of the catalyst; the content of the carrier is 40 to 80% by weight, and more preferably 50 to 65% by weight.
According to the preparation method provided by the invention, the selection of the carrier is as described above, and is not described herein again.
According to the present invention, the impregnation conditions are not particularly limited, and the impregnation time in the step (2) is preferably 12 to 36 hours. The temperature of the impregnation may be room temperature (20-30 ℃ C.)
According to the present invention, preferably, the drying conditions of step (2) include: the temperature is 100 ℃ and 150 ℃, and the time is 5-12 hours.
According to a preferred embodiment of the present invention, the conditions of the pre-calcination in step (2) include: under the oxygen-containing atmosphere, the temperature is 350-550 ℃, and preferably 400-500 ℃; the time is 1 to 8 hours, preferably 2 to 6 hours. The oxygen-containing atmosphere may be pure oxygen or may contain an inert gas (non-reactive gas) in addition to oxygen; the oxygen-containing atmosphere preferably contains oxygen in an amount of 10 vol% or more, and preferably contains air for the purpose of reducing the production cost.
According to a preferred embodiment of the present invention, the calcination conditions in step (2) include: under inert atmosphere, the temperature is 600-900 ℃, and preferably 700-900 ℃; the time is 1-12h, preferably 2-10 h. The inert atmosphere is preferably neon and/or argon. The present invention is illustrated, in part, by the example of argon.
In a third aspect, the present invention provides a carbon-based catalyst obtained by the above-mentioned preparation method. The carbon-based catalyst taking the nano-diamond doped with the modification element as the active component is obtained by the preparation method, and the inventor of the invention finds that the catalyst has higher styrene selectivity and good stability when used for catalyzing the dehydrogenation reaction of ethylbenzene.
Accordingly, in a fourth aspect the present invention provides the use of a carbon based catalyst as described above in the dehydrogenation of ethylbenzene.
In a fifth aspect, the present invention provides a method for preparing styrene by ethylbenzene dehydrogenation, the method comprising:
under the condition of ethylbenzene dehydrogenation reaction, the mixed gas containing ethylbenzene, diluent and oxidant is contacted with a catalyst, and the catalyst is the carbon-based catalyst provided by the invention. The carbon-based catalyst prepared by the method provided by the invention improves the product selectivity in the ethylbenzene dehydrogenation reaction, and avoids the catalyst taking part in the reaction dispersedly in a powder shape, thereby being beneficial to reducing the pressure drop of a reactor and improving the competitiveness of the catalyst in the dehydrogenation reaction process.
According to the present invention, preferably, the diluent may be a gas inert to the reaction, further preferably at least one of nitrogen, helium and argon;
according to the present invention, the oxidizing agent is preferably an oxygen-containing gas, and more preferably a gas having an oxygen content of 10 vol% or more. Further preferably, the oxidant is air and/or oxygen, more preferably oxygen.
According to the method for preparing styrene by ethylbenzene dehydrogenation provided by the invention, the amount of the oxidant is related to the addition amount of ethylbenzene, so that the oxidative dehydrogenation of ethylbenzene can be realized, and preferably, the volume ratio of the ethylbenzene to the oxidant calculated by oxygen is 1: (0.1-2), preferably 1: (0.6-1.2).
According to the method for preparing styrene by ethylbenzene dehydrogenation provided by the invention, preferably, the volume concentration of ethylbenzene in the mixed gas is 0.5-15%.
According to a preferred embodiment of the present invention, the ethylbenzene dehydrogenation reaction conditions comprise: the temperature is 350-580 ℃, and the space velocity of the mixed gas is 1000-18000 mL/g.h; preferably, the temperature is 450-550 ℃, and the space velocity of the mixed gas is 6000-12000 mL/g-h. The reaction may be carried out at normal pressure.
The present invention will be described in detail below by way of examples. In the following examples, the morphology of the catalyst samples was tested on a Phenom G3 scanning electron microscope at a voltage of 10 kV; the particle size of the active component in the carbon-based catalyst is tested by using a FEI Tecnai G2F 20S-TWIN transmission electron microscope in the United states; the content of the modified elements in the active components can be determined by the feeding amount; the catalyst XRD test instrument is a D8 advanced X-ray powder diffractometer of Bruker company, the tube voltage is 40kV, the tube current is 250mA, the Cu target is scanned at the scanning range of 4-70 degrees and the scanning speed is 6(°)/min, and the detector is a solid detector.
The specific surface area of the catalyst sample was calculated by the BET method using a Tristar 3000 type physical adsorption apparatus from Micromeritics, USA, under the specific condition that N is used2As adsorbates, catalyst samples were pretreated by evacuation at 300 ℃.
The raw materials used in the examples are all commercially available products. Wherein the nano-diamond is commercially available from Reliter science and technology Limited of Beijing national; beta-SiC is commercially available from Sicat, France.
Example 1
(1) 0.6894g of glucose and 1.0341g of citric acid were dissolved in 4ml of water at room temperature (25. + -. 1 ℃ C., the same applies hereinafter), and ammonium carbonate equivalent to 0.3013 g of nitrogen was dissolved in the solution after dissolution (a large amount of bubbles were generated); adding ammonium dihydrogen phosphate equivalent to 0.0093 g of phosphorus into the solution, adding 0.6894g of nano diamond powder after forming a uniform and stable solution, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;
(2) soaking 1.35 g of beta-SiC carrier in the suspension, and drying in an oven at 130 ℃ for 12h after adsorption saturation is achieved; then carrying out pre-calcination treatment at 400 ℃ in air atmosphere for 2 h; finally, calcining at 600 ℃ in argon atmosphere for 9h to prepare the required catalyst S-1, wherein the composition and parameters of the catalyst are shown in Table 1. The obtained SEM image, TEM image and XRD image of the carbon-based catalyst are respectively shown in figures 1, 2 and 3, and it can be seen from the images that the nano-diamond active phase can be firmly combined with the carrier, and the XRD spectrum has the diffraction peak of the crystal face of the active phase nano-diamond (111), which also shows that the nano-diamond active phase is successfully loaded on the silicon carbide carrier.
Example 2
(1) Dissolving 0.64g of glucose and 0.8g of citric acid in 4ml of water at room temperature under stirring, and dissolving ammonium carbonate equivalent to 0.15 g of nitrogen in the solution after dissolution (a large amount of bubbles are generated in the process); adding ammonium dihydrogen phosphate equivalent to 0.05 g of phosphorus into the solution, adding 0.8g of nano-diamond powder after forming a uniform and stable solution, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;
(2) soaking 1.86 g of beta-SiC carrier in the suspension, and drying in an oven at 130 ℃ for 12h after the beta-SiC carrier is saturated by adsorption; then carrying out pre-calcination treatment at 400 ℃ in air atmosphere for 2 h; finally, calcining at 700 ℃ in argon atmosphere for 5h to prepare the required catalyst S-2, wherein the composition and parameters of the catalyst are shown in Table 1.
Example 3
(1) Dissolving 0.744g of glucose and 0.682g of citric acid in 4ml of water at room temperature under stirring, and dissolving ammonium carbonate equivalent to 0.3688 g of nitrogen in the solution after dissolution (a large amount of bubbles are generated in the process); adding ammonium dihydrogen phosphate equivalent to 0.0112 g of phosphorus into the solution, adding 0.62g of nano-diamond powder after forming a uniform and stable solution, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;
(2) 1g of beta-SiC carrier is soaked in the suspension, and after the suspension is saturated by adsorption, the suspension is dried in an oven at the temperature of 130 ℃ for 12 hours; then carrying out pre-calcination treatment at 400 ℃ in air atmosphere for 2 h; finally, calcining at 700 ℃ in argon atmosphere for 5h to prepare the required catalyst S-3, wherein the composition and parameters of the catalyst are shown in Table 1.
Example 4
(1) Dissolving 0.68g of glucose and 0.68g of citric acid in 2ml of water and 2ml of absolute ethanol at room temperature under stirring, and dissolving ammonium carbonate equivalent to 0.2971 g of nitrogen in the solution after dissolving (a large amount of bubbles are generated in the process); adding ammonium dihydrogen phosphate equivalent to 0.0229 g of phosphorus into the solution, adding 0.68g of nano-diamond powder after forming a uniform and stable solution, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;
(2) soaking 1.62 g of beta-SiC carrier in the suspension, and drying in an oven at 130 ℃ for 12h after the beta-SiC carrier is saturated by adsorption; then carrying out pre-calcination treatment at 400 ℃ in air atmosphere for 2 h; finally, calcining at 700 ℃ in argon atmosphere for 5h to prepare the required catalyst S-4, wherein the composition and parameters of the catalyst are shown in Table 1.
Example 5
(1) Dissolving 0.6g of glucose and 0.6g of citric acid in 2ml of water and 2ml of absolute ethanol at room temperature under stirring, and dissolving ammonium carbonate equivalent to 0.2905 g of nitrogen in the solution after dissolution (a large amount of bubbles are generated in the process); adding ammonium dihydrogen phosphate equivalent to 0.0448 g of phosphorus into the solution, adding 0.6647g of nano-diamond powder after forming a uniform and stable solution, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;
(2) 3.5 g of beta-SiC carrier is soaked in the suspension, and after the suspension is saturated by adsorption, the suspension is dried in an oven at 130 ℃ for 12 hours; then carrying out precalcination treatment at 500 ℃ in air atmosphere for 4 h; finally, calcining at 800 ℃ in argon atmosphere for 6 hours to prepare the required catalyst S-5, wherein the composition and parameters of the catalyst are shown in Table 1.
Example 6
(1) Dissolving 0.8g of glucose and 0.9g of citric acid in 2ml of water and 2ml of absolute ethanol at room temperature under stirring, and dissolving ammonium carbonate equivalent to 0.2451 g of nitrogen in the solution after dissolution (a large amount of bubbles are generated in the process); adding ammonium dihydrogen phosphate equivalent to 0.0115 g of phosphorus into the solution, adding 0.747g of nano-diamond powder after forming a uniform and stable solution, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;
(2) soaking 1.2 g of beta-SiC carrier in the suspension, and drying in an oven at 130 ℃ for 12h after adsorption saturation is achieved; then carrying out precalcination treatment at 500 ℃ in air atmosphere for 4 h; finally, the catalyst S-6 is prepared by calcining the catalyst at 900 ℃ in the argon atmosphere for 5 hours, and the composition and parameters of the catalyst are shown in Table 1.
Example 7
(1) Dissolving 0.8g of glucose and 0.9g of citric acid in 2ml of water and 2ml of absolute ethanol at room temperature under stirring, and dissolving ammonium carbonate equivalent to 0.2902 g of nitrogen in the solution after dissolution (a large amount of bubbles are generated in the process); adding ammonium dihydrogen phosphate equivalent to 0.0186 g of phosphorus into the solution, adding 0.6912% of nano diamond powder after forming a uniform and stable solution, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;
(2) soaking 0.7 g of beta-SiC carrier in the suspension, and drying in an oven at 130 ℃ for 12h after adsorption saturation is achieved; then carrying out pre-calcination treatment at 400 ℃ in air atmosphere for 2 h; finally, calcining at 700 ℃ in argon atmosphere for 5h to prepare the required catalyst S-7, wherein the composition and parameters of the catalyst are shown in Table 1.
Example 8
(1) Dissolving 0.64g of glucose and 0.64g of citric acid in 2ml of water and 2ml of absolute ethanol at room temperature under stirring, and dissolving ammonium carbonate equivalent to 0.2938 g of nitrogen in the solution after dissolving (a large amount of bubbles are generated in the process); adding ammonium dihydrogen phosphate equivalent to 0.0657 g of phosphorus into the solution, adding 0.636 of nano-diamond powder after forming a uniform and stable solution, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;
(2) 2.1 g of beta-SiC carrier is soaked in the suspension, and after the suspension is saturated by adsorption, the suspension is dried in an oven at 130 ℃ for 12 hours; then carrying out 400 ℃ pre-calcination treatment in air atmosphere for 2 h; finally, calcining at 700 ℃ in argon atmosphere for 5h to prepare the required catalyst S-8, wherein the composition and parameters of the catalyst are shown in Table 1.
Example 9
(1) 0.6894g of glucose and 1.0341g of citric acid are dissolved in 4ml of water at room temperature, and are stirred and dissolved, and ammonium carbonate equivalent to 0.3013 g of nitrogen is dissolved in the solution after the dissolution (a large amount of bubbles are generated in the process); adding ammonium dihydrogen phosphate equivalent to 0.0093 g of phosphorus into the solution, adding boric acid equivalent to 0.02 g of boron into the solution to form a uniform and stable solution, adding 0.6694g of nano diamond powder into the solution, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;
(2) soaking 1.35 g of beta-SiC carrier in the suspension, and drying in an oven at 130 ℃ for 12h after adsorption saturation is achieved; then carrying out pre-calcination treatment at 400 ℃ in air atmosphere for 2 h; finally, calcining at 600 ℃ in argon atmosphere for 9h to prepare the required catalyst S-9, wherein the composition and parameters of the catalyst are shown in Table 1.
Example 10
(1) 1.0341g of glucose and 1.0341g of citric acid are dissolved in 4ml of water at room temperature, and are stirred and dissolved, and ammonium carbonate equivalent to 0.3013 g of nitrogen is dissolved in the solution after the dissolution (a large amount of bubbles are generated in the process); adding ammonium dihydrogen phosphate equivalent to 0.0093 g of phosphorus into the solution, adding 0.6894g of nano diamond powder after forming a uniform and stable solution, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;
(2) soaking 1.35 g of beta-SiC carrier in the suspension, and drying in an oven at 130 ℃ for 12h after adsorption saturation is achieved; then carrying out pre-calcination treatment at 400 ℃ in air atmosphere for 2 h; finally, calcining at 600 ℃ in argon atmosphere for 9h to prepare the required catalyst S-10, wherein the composition and parameters of the catalyst are shown in Table 1.
Example 11
(1) 0.3447g of glucose and 1.0341g of citric acid are dissolved in 4ml of water at room temperature, and are stirred and dissolved, and ammonium carbonate equivalent to 0.3013 g of nitrogen is dissolved in the solution after the dissolution (a large amount of bubbles are generated in the process); adding ammonium dihydrogen phosphate equivalent to 0.0093 g of phosphorus into the solution, adding 0.6894g of nano diamond powder after forming a uniform and stable solution, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;
(2) soaking 1.35 g of beta-SiC carrier in the suspension, and drying in an oven at 130 ℃ for 12h after adsorption saturation is achieved; then carrying out pre-calcination treatment at 400 ℃ in air atmosphere for 2 h; finally, calcining at 600 ℃ in argon atmosphere for 9h to prepare the required catalyst S-11, wherein the composition and parameters of the catalyst are shown in Table 1.
Example 12
(1) 0.6894g of glucose and 1.3788g of citric acid are dissolved in 4ml of water at room temperature, and are stirred and dissolved, and ammonium carbonate equivalent to 0.3013 g of nitrogen is dissolved in the solution after the dissolution (a large amount of bubbles are generated in the process); adding ammonium dihydrogen phosphate equivalent to 0.0093 g of phosphorus into the solution, adding 0.6894g of nano diamond powder after forming a uniform and stable solution, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;
(2) soaking 1.35 g of beta-SiC carrier in the suspension, and drying in an oven at 130 ℃ for 12h after adsorption saturation is achieved; then carrying out pre-calcination treatment at 400 ℃ in air atmosphere for 2 h; finally, calcining at 600 ℃ in argon atmosphere for 9h to prepare the required catalyst S-12, wherein the composition and parameters of the catalyst are shown in Table 1.
Example 13
(1) 0.6894g of glucose and 0.3447g of citric acid are dissolved in 4ml of water at room temperature, and are stirred and dissolved, and ammonium carbonate equivalent to 0.3013 g of nitrogen is dissolved in the solution after the dissolution (a large amount of bubbles are generated in the process); adding ammonium dihydrogen phosphate equivalent to 0.0093 g of phosphorus into the solution, adding 0.6894g of nano diamond powder after forming a uniform and stable solution, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;
(2) soaking 1.35 g of beta-SiC carrier in the suspension, and drying in an oven at 130 ℃ for 12h after adsorption saturation is achieved; then carrying out pre-calcination treatment at 400 ℃ in air atmosphere for 2 h; finally, calcining at 600 ℃ in argon atmosphere for 9h to prepare the required catalyst S-13, wherein the composition and parameters of the catalyst are shown in Table 1.
Example 14
The process of example 1 is followed except that step (2) precalcination and calcination are both in an air atmosphere, with the specific step (2) comprising:
(2) soaking 1.35 g of beta-SiC carrier in the suspension, and drying in an oven at 130 ℃ for 12h after adsorption saturation is achieved; then carrying out pre-calcination treatment at 400 ℃ in air atmosphere for 2 h; finally, calcining at 600 ℃ in air atmosphere for 9h to obtain the required catalyst S-14, wherein the composition and parameters of the catalyst are shown in Table 1.
Example 15
Following the procedure of example 1, except that the nitrogen source and the phosphorus source were added in different amounts, the specific step (1) included:
(1) 0.6894g of glucose and 1.0341g of citric acid are dissolved in 4ml of water at room temperature, and are stirred and dissolved, and ammonium carbonate equivalent to 0.2083 g of nitrogen is dissolved in the solution after the dissolution (a large amount of bubbles are generated in the process); adding ammonium dihydrogen phosphate equivalent to 0.1023 g of phosphorus into the solution, adding 0.6894g of nano diamond powder after forming a uniform and stable solution, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;
(2) soaking 1.35 g of beta-SiC carrier in the suspension, and drying in an oven at 130 ℃ for 12h after adsorption saturation is achieved; then carrying out 400 ℃ pre-calcination treatment in air atmosphere for 2 h; finally, calcining at 600 ℃ in argon atmosphere for 9h to prepare the required catalyst S-15, wherein the composition and parameters of the catalyst are shown in Table 1.
Example 16
The process of example 1 is followed except that, in step (1), no ammonium dihydrogen phosphate is added, i.e. no phosphorus source is introduced, and the specific step (1) comprises:
(1) dissolving 0.6894g of glucose and 1.0341g of citric acid in 4ml of water at room temperature, stirring and dissolving, dissolving 0.3013 g of nitrogen-containing ammonium carbonate in the solution after the dissolution (a large amount of bubbles are generated in the process), adding 0.6987g of nano diamond powder after a uniform and stable solution is formed, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;
(2) soaking 1.35 g of beta-SiC carrier in the suspension, and drying in an oven at 130 ℃ for 12h after adsorption saturation is achieved; then carrying out 400 ℃ pre-calcination treatment in air atmosphere for 2 h; finally, calcining at 600 ℃ in argon atmosphere for 9h to prepare the required catalyst S-16, wherein the composition and parameters of the catalyst are shown in Table 1.
Example 17
Following the procedure of example 1, except that ammonium carbonate was not added in step (1), i.e., no nitrogen source was introduced, the specific step (1) included:
(1) dissolving 0.6894g of glucose and 1.0341g of citric acid in 4ml of water at room temperature, stirring and dissolving, adding ammonium dihydrogen phosphate equivalent to 0.0093 g of phosphorus into the solution after the glucose and the citric acid are dissolved, adding 0.9907g of nano diamond powder after a uniform and stable solution is formed, and performing ultrasonic treatment for 30min to form uniform and stable suspension;
(2) soaking 1.35 g of beta-SiC carrier in the suspension, and drying in an oven at 130 ℃ for 12h after adsorption saturation is achieved; then carrying out 400 ℃ pre-calcination treatment in air atmosphere for 2 h; finally, calcining at 600 ℃ in argon atmosphere for 9h to prepare the required catalyst S-17, wherein the composition and parameters of the catalyst are shown in Table 1.
TABLE 1
Note: the content of the modified element is based on the total amount of the active components, and the content of the active components is based on the total amount of the carbon-based catalyst.
Test example 1
The experimental example is used to illustrate the catalytic performance of the carbon-based catalyst provided by the present invention in the process of ethylbenzene oxidative dehydrogenation.
The ethylbenzene oxidative dehydrogenation reaction is carried out in an isothermal fixed bed reactor, and the carbon-based catalysts prepared in the above examples are used as test samples: the catalyst amount was 150mg, the reaction temperature was 450 ℃, the reaction gas flow rate was 30mL/min, the ethylbenzene content in the reaction gas was 2.9 vol%, the oxygen content was 2.9 vol%, and the balance was helium, and the ethylbenzene conversion and styrene selectivity at 50 hours of reaction are shown in table 2.
TABLE 2
The results in table 2 show that, when the reaction temperature is 450 ℃, the catalyst dosage is 150mg, the total flow of the reaction gas is 30ml/min, and the molar ratio of ethylbenzene to oxygen is 1:1, the conversion rate can reach 33.9% at most and the selectivity can reach 92.9% at most after stable operation for 50 hours, and a good technical effect is achieved.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (14)
1. The carbon-based catalyst is characterized by comprising a carrier and an active component loaded on the carrier, wherein the active component comprises nano diamond and a modifying element, and the modifying element is at least one selected from nitrogen element, phosphorus element and boron element.
2. Carbon-based catalyst according to claim 1, wherein the support is silicon carbide, preferably β -SiC.
3. The carbon-based catalyst according to claim 1, wherein the content of modifying elements is 0.5-45 wt. -%, preferably 20-38 wt. -%, based on the total amount of the active components;
preferably, the modifying element comprises nitrogen and/or phosphorus, preferably comprises nitrogen and phosphorus, and further preferably, the mass ratio of the nitrogen to the phosphorus is (1-40): 1, preferably (3-33): 1.
4. the carbon-based catalyst according to claim 1, wherein the specific surface area of the carbon-based catalyst is 50-240m2/g；
Preferably, the particle size of the active component is 1-10 nm.
5. The carbon-based catalyst according to any one of claims 1 to 4, wherein the active component is contained in an amount of 20 to 60 wt% and the support is contained in an amount of 40 to 80 wt%, based on the total amount of the carbon-based catalyst;
preferably, the content of the active component is 35-50 wt% and the content of the carrier is 50-65 wt% based on the total amount of the carbon-based catalyst.
6. A preparation method of a carbon-based catalyst comprises the following steps:
(1) mixing the nano-diamond, a compound containing modified elements, glucose, a dispersing agent and a solvent to obtain an active component suspension; the compound containing the modification element is selected from at least one of a nitrogen source, a boron source and a phosphorus source;
(2) and (2) soaking the carrier into the active component suspension liquid in the step (1), and sequentially drying, pre-calcining and calcining.
7. The preparation method according to claim 6, wherein the dispersant is selected from at least one of citric acid, ammonium citrate and polyethylene glycol, preferably citric acid;
preferably, the mass ratio of the dispersing agent to the nano-diamond is 0.5-2: 1, preferably 1 to 1.5: 1.
8. the production method according to claim 6, wherein the glucose to nanodiamond mass ratio is 0.5-1.5: 1, preferably 0.8 to 1.2: 1.
9. the production method according to claim 6, wherein,
the carrier is silicon carbide, preferably beta-SiC;
the solvent is water and/or an organic solvent;
the nitrogen source is selected from at least one of ammonium carbonate, ammonium sulfate, urea and ammonia water, and ammonium carbonate is preferred;
the boron source is selected from boric acid and/or sodium tetraborate, preferably boric acid;
the phosphorus source is selected from at least one of ammonium dihydrogen phosphate, diammonium hydrogen phosphate and ammonium phosphate, and is preferably ammonium dihydrogen phosphate;
preferably, the compound containing the modifying element is a nitrogen source and/or a phosphorus source, preferably a nitrogen source and a phosphorus source, and further preferably, the mass ratio of the nitrogen source in terms of nitrogen element to the phosphorus source in terms of phosphorus element is (1-40): 1, preferably (3-33): 1;
preferably, the mixing in step (1) is carried out under ultrasonic conditions for 10-200min, preferably 20-60 min.
10. The production method according to claim 6, wherein the amount of the nanodiamond and the compound containing the modifying element is such that the content of the modifying element in the obtained catalyst is 0.5 to 45% by weight, preferably 20 to 38% by weight, based on the total amount of the nanodiamond and the modifying element;
the dosage of the nano-diamond, the compound containing the modified element and the carrier is such that the content of the nano-diamond and the modified element in the prepared catalyst is 20-60 wt%, preferably 35-50 wt% based on the total amount of the catalyst; the content of the carrier is 40 to 80% by weight, preferably 50 to 65% by weight.
11. The production method according to any one of claims 6 to 10,
the dipping time in the step (2) is 12-36 hours;
the drying conditions in the step (2) comprise: the temperature is 100-150 ℃, and the time is 5-12 hours;
preferably, the pre-calcining conditions of step (2) include: under the oxygen-containing atmosphere, the temperature is 350-550 ℃, and preferably 400-500 ℃; the time is 1 to 8 hours, preferably 2 to 6 hours;
preferably, the calcining conditions of step (2) include: under inert atmosphere, the temperature is 600-900 ℃, and preferably 700-900 ℃; the time is 1 to 12 hours, preferably 2 to 10 hours;
preferably, the oxygen-containing atmosphere is air;
preferably, the inert atmosphere is neon and/or argon.
12. A carbon-based catalyst obtainable by the process of any one of claims 6 to 11.
13. Use of a carbon based catalyst according to any one of claims 1 to 5 and 12 in ethylbenzene dehydrogenation reactions.
14. A process for the dehydrogenation of ethylbenzene to styrene, which process comprises:
contacting a mixed gas containing ethylbenzene, a diluent and an oxidant with a catalyst under ethylbenzene dehydrogenation reaction conditions, wherein the catalyst is the carbon-based catalyst in any one of claims 1-5 and 12;
preferably, the diluent is selected from at least one of inert gases, preferably from at least one of nitrogen, helium and argon;
preferably, the oxidant is an oxygen-containing gas, further preferably air and/or oxygen, more preferably oxygen;
preferably, the volume ratio of ethylbenzene to oxidant in terms of oxygen is 1: (0.1-2), preferably 1: (0.6-1.2);
preferably, the volume concentration of the ethylbenzene in the mixed gas is 0.5-15%;
preferably, the ethylbenzene dehydrogenation reaction conditions comprise: the temperature is 350-580 ℃, and the space velocity of the mixed gas is 1000-18000 mL/g-h.
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