CN115069234A - Method for preparing hollow CrO simultaneously by detoxication and purification of chromium-containing waste salt x /Al 2 O 3 Method for preparing catalyst and its application - Google Patents
Method for preparing hollow CrO simultaneously by detoxication and purification of chromium-containing waste salt x /Al 2 O 3 Method for preparing catalyst and its application Download PDFInfo
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- CN115069234A CN115069234A CN202210750028.1A CN202210750028A CN115069234A CN 115069234 A CN115069234 A CN 115069234A CN 202210750028 A CN202210750028 A CN 202210750028A CN 115069234 A CN115069234 A CN 115069234A
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- chromium
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- containing waste
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- 239000011651 chromium Substances 0.000 title claims abstract description 170
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 title claims abstract description 145
- 229910052804 chromium Inorganic materials 0.000 title claims abstract description 143
- 239000003054 catalyst Substances 0.000 title claims abstract description 95
- 229910018072 Al 2 O 3 Inorganic materials 0.000 title claims abstract description 84
- 150000003839 salts Chemical class 0.000 title claims abstract description 77
- 239000002699 waste material Substances 0.000 title claims abstract description 58
- 238000000034 method Methods 0.000 title claims abstract description 54
- 238000000746 purification Methods 0.000 title claims abstract description 13
- 238000001035 drying Methods 0.000 claims abstract description 26
- 239000000706 filtrate Substances 0.000 claims abstract description 23
- 229910002706 AlOOH Inorganic materials 0.000 claims abstract description 22
- 239000002243 precursor Substances 0.000 claims abstract description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 19
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 18
- 238000010438 heat treatment Methods 0.000 claims abstract description 15
- 238000001027 hydrothermal synthesis Methods 0.000 claims abstract description 15
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 13
- 238000005406 washing Methods 0.000 claims abstract description 11
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 claims abstract description 10
- 238000001784 detoxification Methods 0.000 claims abstract description 8
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 44
- 239000007864 aqueous solution Substances 0.000 claims description 42
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 39
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Natural products NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 39
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 claims description 24
- 238000006356 dehydrogenation reaction Methods 0.000 claims description 22
- 239000011780 sodium chloride Substances 0.000 claims description 22
- 239000004202 carbamide Substances 0.000 claims description 18
- 238000001816 cooling Methods 0.000 claims description 18
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 claims description 18
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 16
- 235000011152 sodium sulphate Nutrition 0.000 claims description 16
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 claims description 12
- 150000001335 aliphatic alkanes Chemical class 0.000 claims description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 10
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 claims description 10
- 238000000967 suction filtration Methods 0.000 claims description 10
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 9
- 235000010265 sodium sulphite Nutrition 0.000 claims description 9
- 238000003756 stirring Methods 0.000 claims description 8
- NWZSZGALRFJKBT-KNIFDHDWSA-N (2s)-2,6-diaminohexanoic acid;(2s)-2-hydroxybutanedioic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O.NCCCC[C@H](N)C(O)=O NWZSZGALRFJKBT-KNIFDHDWSA-N 0.000 claims description 7
- IKDUDTNKRLTJSI-UHFFFAOYSA-N hydrazine monohydrate Substances O.NN IKDUDTNKRLTJSI-UHFFFAOYSA-N 0.000 claims description 7
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 claims description 6
- UMGDCJDMYOKAJW-UHFFFAOYSA-N thiourea Chemical compound NC(N)=S UMGDCJDMYOKAJW-UHFFFAOYSA-N 0.000 claims description 6
- 150000001336 alkenes Chemical class 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 239000011259 mixed solution Substances 0.000 claims description 4
- BNGXYYYYKUGPPF-UHFFFAOYSA-M (3-methylphenyl)methyl-triphenylphosphanium;chloride Chemical compound [Cl-].CC1=CC=CC(C[P+](C=2C=CC=CC=2)(C=2C=CC=CC=2)C=2C=CC=CC=2)=C1 BNGXYYYYKUGPPF-UHFFFAOYSA-M 0.000 claims description 3
- 229920000877 Melamine resin Polymers 0.000 claims description 3
- 239000002202 Polyethylene glycol Substances 0.000 claims description 3
- 239000011668 ascorbic acid Substances 0.000 claims description 3
- 235000010323 ascorbic acid Nutrition 0.000 claims description 3
- 229960005070 ascorbic acid Drugs 0.000 claims description 3
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 claims description 3
- 229920001223 polyethylene glycol Polymers 0.000 claims description 3
- WBHQBSYUUJJSRZ-UHFFFAOYSA-M sodium bisulfate Chemical compound [Na+].OS([O-])(=O)=O WBHQBSYUUJJSRZ-UHFFFAOYSA-M 0.000 claims description 3
- 229910000342 sodium bisulfate Inorganic materials 0.000 claims description 3
- 239000012279 sodium borohydride Substances 0.000 claims description 3
- 229910000033 sodium borohydride Inorganic materials 0.000 claims description 3
- 238000006243 chemical reaction Methods 0.000 abstract description 54
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 abstract description 14
- 238000011068 loading method Methods 0.000 abstract description 5
- 238000002156 mixing Methods 0.000 abstract 1
- 229910052799 carbon Inorganic materials 0.000 description 21
- 239000000047 product Substances 0.000 description 21
- 238000002360 preparation method Methods 0.000 description 17
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 12
- 238000010586 diagram Methods 0.000 description 11
- 239000002440 industrial waste Substances 0.000 description 9
- 230000008569 process Effects 0.000 description 9
- 230000035484 reaction time Effects 0.000 description 9
- 238000001704 evaporation Methods 0.000 description 8
- 238000011049 filling Methods 0.000 description 8
- 230000008901 benefit Effects 0.000 description 7
- 238000003760 magnetic stirring Methods 0.000 description 7
- 239000000243 solution Substances 0.000 description 7
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 6
- 239000006185 dispersion Substances 0.000 description 6
- 229910052709 silver Inorganic materials 0.000 description 6
- 239000004332 silver Substances 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 5
- 239000010446 mirabilite Substances 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 238000005245 sintering Methods 0.000 description 5
- 238000002441 X-ray diffraction Methods 0.000 description 4
- 239000002585 base Substances 0.000 description 4
- 239000002135 nanosheet Substances 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 230000003197 catalytic effect Effects 0.000 description 3
- 238000012512 characterization method Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 231100000331 toxic Toxicity 0.000 description 3
- 230000002588 toxic effect Effects 0.000 description 3
- 229910021555 Chromium Chloride Inorganic materials 0.000 description 2
- 238000003917 TEM image Methods 0.000 description 2
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 2
- 229910052783 alkali metal Inorganic materials 0.000 description 2
- 150000001340 alkali metals Chemical class 0.000 description 2
- 239000004411 aluminium Substances 0.000 description 2
- -1 carbon alkane Chemical class 0.000 description 2
- 229910000423 chromium oxide Inorganic materials 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000012495 reaction gas Substances 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- RTWBUUQMFBMODW-UHFFFAOYSA-J [Cl-].[Cr+3].[Na+].[Cl-].[Cl-].[Cl-] Chemical compound [Cl-].[Cr+3].[Na+].[Cl-].[Cl-].[Cl-] RTWBUUQMFBMODW-UHFFFAOYSA-J 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- REDXJYDRNCIFBQ-UHFFFAOYSA-N aluminium(3+) Chemical compound [Al+3] REDXJYDRNCIFBQ-UHFFFAOYSA-N 0.000 description 1
- 239000001273 butane Substances 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 150000001844 chromium Chemical class 0.000 description 1
- 229910001430 chromium ion Inorganic materials 0.000 description 1
- VQWFNAGFNGABOH-UHFFFAOYSA-K chromium(iii) hydroxide Chemical class [OH-].[OH-].[OH-].[Cr+3] VQWFNAGFNGABOH-UHFFFAOYSA-K 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 210000003298 dental enamel Anatomy 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000010335 hydrothermal treatment Methods 0.000 description 1
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 description 1
- 229910017053 inorganic salt Inorganic materials 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000002808 molecular sieve Substances 0.000 description 1
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 1
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 1
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 238000007613 slurry method Methods 0.000 description 1
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 1
- MILMJAFFMWCPLL-UHFFFAOYSA-J sodium;chromium(3+);disulfate Chemical compound [Na+].[Cr+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O MILMJAFFMWCPLL-UHFFFAOYSA-J 0.000 description 1
- 239000002910 solid waste 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
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
- B01J23/24—Chromium, molybdenum or tungsten
- B01J23/26—Chromium
-
- 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
- B01J23/002—Mixed oxides other than spinels, e.g. perovskite
-
- 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
- B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
- B01J35/391—Physical properties of the active metal ingredient
- B01J35/393—Metal or metal oxide crystallite size
-
- 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
- B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
- B01J37/0018—Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
-
- 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
- C07C5/3332—Catalytic processes with metal oxides or metal sulfides
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- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a method for preparing hollow CrO simultaneously by detoxification and purification of chromium-containing waste salt x /Al 2 O 3 A method for preparing the catalyst and application thereof. Belongs to the technical field of chromium removal of chromium-containing waste salt and high-value utilization of chromium resources. The chromium-containing waste salt is detoxified and purified to prepare hollow CrO simultaneously x /Al 2 O 3 Dissolving chromium-containing waste salt, aluminum salt and pore-forming agent in water, adding a reducing agent, and carrying out hydrothermal reaction to obtain filtrate and filter residue; washing the filter residue to obtain Cr (OH) 3 -an AlOOH precursor; heating, concentrating, crystallizing and drying the filtrate to obtain dechromized salt; mixing Cr (OH) 3 Roasting AlOOH precursor to obtain hollow CrO x /Al 2 O 3 A catalyst. By the inventionThe method can realize the high-efficiency and thorough dechroming of industrial chromium-containing waste salt and obtain the low-chromium-loading CrO with high ethane conversion rate (25.6 percent) and excellent thermal stability x /Al 2 O 3 A catalyst.
Description
Technical Field
The invention belongs to the technical field of chromium removal of chromium-containing waste salt and high-value utilization of chromium resources, and relates to a method for preparing hollow CrO simultaneously by detoxification and purification of chromium-containing waste salt x /Al 2 O 3 A method for preparing the catalyst and application thereof.
Background
The chromium-containing waste salt is a solid waste which is generated in the chromium salt industry in the generation process and takes inorganic salt as a main component, and mainly comprises three main types of sodium chloride, sodium sulfate and sodium bisulfate. Chromium is a non-renewable resource, and improper disposal of chromium-containing waste salt can seriously harm human health and ecological environment and is a waste of resources. How to harmlessly utilize industrial chromium-containing waste salt and recycle the waste salt is the research focus of a plurality of scholars.
Since 2000 years, research on the reuse of industrial chromium-containing waste salts has gradually emerged. Li Xianrong, Ma shui et al developed a method for refining anhydrous sodium sulfate from chromium-containing mirabilite (ZL201310533304.X A method for refining anhydrous sodium sulfate from chromium-containing mirabilite). The method adopts a crystal slurry method to produce the anhydrous sodium sulphate, but the hexavalent chromium in the produced anhydrous sodium sulphate exceeds the standard due to the problem that the hexavalent chromium is wrapped by the crystal slurry. In addition, in the method, sodium sulfite is used as a reducing agent, sodium hydroxide is used as a neutralizing agent, and the two raw materials are too expensive for the low-value product anhydrous sodium sulphate, so that the production cost of the anhydrous sodium sulphate is high, and the actual productivity cannot be realized. Zhangyuan has developed a method for preparing anhydrous sodium sulfate from chromium-containing mirabilite (ZL 201711117496.0: a method for preparing anhydrous sodium sulfate from chromium-containing mirabilite), and due to the adoption of a hydrothermal reduction process, the equipment investment is increased, the requirement of large-batch treatment of chromium-containing mirabilite waste salt cannot be met, and the market competitiveness cannot be formed.
At present, the dehydrogenation catalysts matched with the alkane dehydrogenation industrial technology developed by enterprises at home and abroad are respectively Pt/Al 2 O 3 Base catalyst and Cr 2 O 3 /Al 2 O 3 A base catalyst. Chinese patent application 201310396586.3: a butane dehydrogenation catalyst and a preparation method relate to an alkane dehydrogenation catalyst, wherein Cr in the catalyst 2 O 3 Is 12-20% by mass, and is mixed with a certain proportion of K 2 O，V 2 O 5 ，SiO 2 And the molecular sieve is impregnated and roasted to obtain Cr with certain carbon deposit resistance 2 O 3 /Al 2 O 3 A base catalyst. Similarly, ZL201210408472.1 a low carbon alkane dehydrogenation makes olefin catalyst and its preparation method and application disclose a low carbon alkane dehydrogenation catalyst preparation method, active component chromium is impregnated to alumina carrier step by step before and after impregnating alkali metal catalyst promoter component respectively, wherein the content of chromium oxide is 10-30%, the content of alkali metal calcination is 0.5-3.0%. Alkane dehydrogenated Cr prepared by the above method 2 O 3 /Al 2 O 3 The base catalyst improves the activity of the dehydrogenation catalyst and the selectivity of propylene to a certain extent, however, the preparation method of the above catalyst generally adopts a dipping roasting method, and the dosage of the active component chromium is more than 10%. The excessively high chromium loading in the catalyst not only makes it difficult to control the dispersion state of the Cr species to make it low in dispersion degree and poor in stability during the preparation process thereof, but also poses a threat to the ecological environment by a large amount of toxic hexavalent chromium contained in the catalyst when the catalyst is deactivated and discarded.
Aiming at the current situation of processing and resource utilization of industrial chromium-containing waste salt, the problem of chromium pollution in the industrial chromium-containing waste salt is partially solved, but the resource-obtained product has little economic benefit basically because natural salt mine occupies a large share of the market at low price. If the catalyst material with high added value and excellent performance can be obtained while detoxification is carried out, the catalyst material has application value and practical significance.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a method for preparing hollow CrO simultaneously by detoxicating and purifying chromium-containing waste salt x /Al 2 O 3 A method of preparing the catalyst.
The invention also aims to provide the detoxication extract for the chromium-containing waste saltPure simultaneous preparation of hollow CrO x /Al 2 O 3 Application of the catalyst.
The purpose of the invention is realized by the following technical scheme:
method for preparing hollow CrO simultaneously by detoxication and purification of chromium-containing waste salt x /Al 2 O 3 A process for the preparation of a catalyst comprising the steps of:
(1) dissolving chromium-containing waste salt, aluminum salt and pore-forming agent in water to obtain aqueous solution; adding a reducing agent into the aqueous solution, and stirring to obtain a mixed solution;
(2) carrying out hydrothermal reaction on the mixed solution, cooling and carrying out suction filtration to obtain filtrate and filter residue;
(3) washing the filter residue obtained in the step (2), and drying to obtain Cr (OH) 3 -an AlOOH precursor;
(4) heating, concentrating, crystallizing and drying the filtrate to obtain dechromized salt;
(5) cr (OH) obtained in the step (3) 3 Heating the AlOOH precursor to 500-800 ℃ at the heating rate of 1-10 ℃/min and roasting for 2-10 h to obtain hollow CrO x /Al 2 O 3 A catalyst.
In the step (1), the chromium-containing waste salt preferably comprises at least one of chromium-containing sodium sulfate, chromium-containing sodium hydrogen sulfate and chromium-containing sodium chloride; more preferably at least one of chromium-containing sodium sulfate and chromium-containing sodium chloride.
In the step (1), the aluminum salt preferably includes at least one of aluminum sulfate, aluminum nitrate and aluminum chloride; more preferably at least one of aluminum sulfate and aluminum chloride.
In the step (1), the pore-forming agent preferably comprises at least one of thiourea, melamine, urea, citric acid and polyethylene glycol; more preferably urea.
In the step (1), the reducing agent preferably comprises at least one of sodium sulfite, ascorbic acid, hydrazine hydrate and sodium borohydride; more preferably at least one of sodium sulfite and hydrazine hydrate.
In the step (1), the chromium-containing waste salt, the aluminum salt and the pore-forming agent are preferably calculated according to the mass ratio of 1-25: 0.1-8: 0.5-15; more preferably, the mass ratio is 4.3-21.5: 0.7: 0.7.
In the step (1), the chromium-containing waste salt and the reducing agent are preferably calculated according to the mass ratio of 1-25: 0.032-0.15; more preferably, the mass ratio is 4.3-21.5: 0.032-0.15.
In the step (2), the hydrothermal reaction conditions are preferably: reacting for 1-48 h at 120-200 ℃.
In the step (3), the drying conditions are preferably as follows: drying for 8-12 h at 70-90 ℃; more preferably: drying at 80 ℃ for 10 h.
The chromium-containing waste salt is detoxified and purified to prepare hollow CrO x /Al 2 O 3 Method for detoxifying chromium-containing waste salt and/or preparing CrO x /Al 2 O 3 Application in catalysts.
CrO x /Al 2 O 3 The catalyst is prepared by the method.
The CrO x /Al 2 O 3 Use of a catalyst for the dehydrogenation of alkanes to olefins.
By using CrO x /Al 2 O 3 A process for preparing olefin by dehydrogenating alkane with catalyst includes such steps as adding CrO x /Al 2 O 3 And (3) carrying out high-temperature dehydrogenation reaction on the catalyst in a mixed atmosphere of alkane and nitrogen.
The alkane and nitrogen are preferably in a volume ratio of 2: 8.
The high-temperature dehydrogenation reaction is preferably carried out for 6 hours at 500-750 ℃.
The chromium-containing waste salt is used as a morphology regulator of the catalyst on one hand and provides a chromium source on the other hand. The method takes inorganic aluminum salt (at least one of aluminum sulfate, aluminum nitrate and aluminum chloride) as an aluminum source, at least one of thiourea, melamine, urea, citric acid and polyethylene glycol as a pore-forming agent, and at least one of sodium sulfite, ascorbic acid, hydrazine hydrate and sodium borohydride as a toxic hexavalent chromium reducing agent. Dissolving aluminum salt, pore-forming agent, chromium-containing waste salt and reducing agent according to a certain proportion, under the condition of weak alkaline hydrothermal reaction firstly producing hydroxide aluminium nano-sheet by aluminium ion, at the same time producing hydroxide aluminium nano-sheetThe trivalent chromium ions also form chromium hydroxides and produce strong interactions with the aluminum oxyhydroxide. Under the action of the morphology regulator chromium-containing waste salt, the nano-sheets of the hydroxyl alumina composite chromium oxide are self-assembled to form a hollow flower-shaped structure with super-high thermal stability. After the hydrothermal process is finished, solid-liquid separation is carried out, the filtrate is heated, concentrated and crystallized to obtain chromium-removed industrial salt, and the filter residue is washed, dried and roasted in a specified temperature range to obtain the ultrastable CrO with the hollow flower-shaped structure x /Al 2 O 3 A catalyst.
Compared with the prior art, the invention has the following advantages and effects:
(1) the invention aims to provide a simple process for preparing low-chromium-loading-capacity ultrastable CrO with a hollow structure by using chromium-containing waste salt as a morphology regulator and a chromium source while performing dechroming on industrial chromium-containing waste salt x /Al 2 O 3 A catalyst. The method can realize the high-efficiency and thorough dechroming of industrial chromium-containing waste salt and obtain the low-chromium-loading CrO with high ethane conversion rate (25.6%) and excellent thermal stability x /Al 2 O 3 A catalyst. Through repeated experimental research, the process for detoxifying the industrial chromium-containing waste salt and recycling a small amount of chromium in the chromium-containing waste salt is explored, and has the advantages of low raw material cost, low energy consumption, good economic benefit and environmental friendliness. The process reduces the toxic hexavalent chromium into trivalent chromium and stabilizes the trivalent chromium on the hydroxy alumina with special appearance to prepare the low-chromium-loading ultrastable CrO by simple hydrothermal treatment of industrial chromium-containing waste salt x /Al 2 O 3 The catalyst not only achieves the aim of thoroughly detoxifying industrial chromium-containing waste salt, but also obtains CrO with low chromium loading capacity, super-stable type and high ethylene conversion rate x /Al 2 O 3 The catalyst improves the utilization rate of Cr resources and has higher environmental significance and economic benefit.
(2) The invention provides a method for preparing hollow CrO while detoxifying and purifying chromium-containing waste salt x /Al 2 O 3 Method of preparing catalyst, and the CrO x /Al 2 O 3 Catalyst applied to preparation of low-carbon olefin by low-carbon alkane dehydrogenationThe process realizes the dechromization treatment of industrial chromium-containing waste salt and the high-performance utilization of chromium resources at the same time. The invention has simple detoxification process, thorough detoxification, small investment, fast effect and no secondary pollution. The industrial salt purified by the method can be used for preparing glass, enamel, refrigerating mixer and the like, and the prepared CrO with the hollow flower-like structure x /Al 2 O 3 The catalyst has excellent catalytic performance for preparing low-carbon olefin by low-carbon alkane dehydrogenation.
(3) The invention aims to prepare CrO with high catalytic activity and stability by resource utilization of chromium in the process of detoxification of industrial chromium-containing waste salt x /Al 2 O 3 Catalyst, and CrO to be produced x /Al 2 O 3 The catalyst is applied to preparing low-carbon olefin by low-carbon alkane dehydrogenation, realizes the detoxification of industrial chromium-containing waste salt, simultaneously utilizes chromium resources with high performance, and improves the economic benefit of enterprises. In addition, the process is simple and easy to implement, the catalyst with high added value and excellent performance is obtained, and the dechromized purified industrial salt is obtained, so that the method has good market economic value and environmental benefit.
Drawings
FIG. 1 shows that chromium-containing waste salt is detoxified and purified while preparing hollow CrO x /Al 2 O 3 Process flow diagram for catalyst.
FIG. 2 is a physical diagram and an XRD diagram of chromium-containing sodium sulfate in industrial waste salt; wherein a is a real figure of industrial waste salt containing chromium sodium sulfate; b is an XRD pattern of chromium-containing sodium sulfate in the industrial waste salt.
FIG. 3 is a physical diagram and XRD diagram of chromium-containing sodium chloride in industrial waste salt; wherein a is a real object diagram of industrial waste salt containing chromium and sodium chloride; b is an XRD pattern of the industrial waste salt containing chromium and sodium chloride.
FIG. 4 shows CrO prepared by using chromium-containing sodium sulfate as chromium source and morphology control agent in industrial waste salt in example 1 x /Al 2 O 3 Characterization graphs of the catalyst and the dechromised anhydrous sodium sulfate product; wherein a is CrO prepared in example 1 x /Al 2 O 3 SEM image of catalyst; b is CrO prepared in example 1 x /Al 2 O 3 TEM images of the catalyst; c. CCrO prepared for example 1 x /Al 2 O 3 XRD pattern of the catalyst; d is a real figure of the dechrominated anhydrous sodium sulfate product obtained in example 1.
FIG. 5 shows CrO prepared in example 6 by using chromium-containing sodium chloride as a chromium source and a morphology control agent x /Al 2 O 3 A characterization map of the catalyst; wherein a is CrO prepared in example 6 x /Al 2 O 3 SEM pictures of the catalyst; b is CrO prepared in example 6 x /Al 2 O 3 TEM images of the catalyst; c is CrO prepared in example 6 x /Al 2 O 3 XRD pattern of the catalyst; d is a physical diagram of the dechromised anhydrous sodium chloride product obtained in example 6.
FIG. 6 is CrO prepared in example 1, example 6 and comparative example 1 x /Al 2 O 3 Ethane dehydrogenation performance results of the catalyst.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.
The reagents used in the examples were all purchased from alatin.
The physical diagram and XRD diagram of the chromium-containing sodium sulfate used as industrial waste salt in the examples are shown in FIG. 2. The physical diagram and XRD diagram of the industrial waste salt containing chromium sodium chloride are shown in figure 3.
Example 1
Method for preparing hollow CrO simultaneously by detoxication and purification of chromium-containing waste salt x /Al 2 O 3 The preparation method of the catalyst, as shown in figure 1, comprises the following steps:
1) 4.3g of chromium-containing sodium sulfate (provided by silver river chemical Co., Ltd. of Sichuan province, chromium content is 1.02mg/g), 0.7g of aluminum sulfate and 0.7g of urea are dissolved in 70mL of water, and the mixture is magnetically stirred to be completely dissolved to obtain a yellow aqueous solution; at the moment, the concentration of chromium in the aqueous solution is 62.7mg/L, 32mg of sodium sulfite is added into the aqueous solution as a reducing agent, and magnetic stirring is continued for 15min to promote hexavalent chromium in the solution to be completely reduced into trivalent chromium, so that a green aqueous solution is obtained;
2) transferring the green aqueous solution obtained in the step 1) to a 100mL reaction kettle to ensure that the filling degree is 70%, and carrying out hydrothermal reaction; setting the reaction temperature to be 120 ℃ and the reaction time to be 48 h; obtaining a solid-liquid mixture;
3) after the reaction is finished, naturally cooling to room temperature, and performing suction filtration to obtain filtrate and filter residue;
4) washing the filter residue with water for multiple times, and drying in an oven at 80 deg.C for 10h to obtain Cr (OH) 3 -an AlOOH precursor;
5) evaporating and concentrating the filtrate, crystallizing and drying to obtain the anhydrous sodium sulfate product after dechromization, as shown in figure 4 d. In the anhydrous sodium sulfate product after dechromization, the content of chromium is lower than 0.001mg/g, and the product meets the standard requirement of industrial salt GBT/6009-;
6) the Cr (OH) obtained in the step 4) 3 Placing the AlOOH precursor in a muffle furnace, raising the temperature to 500 ℃ at the heating rate of 1 ℃/min, keeping the temperature for 2h, and naturally cooling to room temperature to obtain the nano-sheet assembled CrO with the hollow flower-shaped structure x /Al 2 O 3 Catalyst, as shown in FIGS. 4 a-c; as can be seen from FIG. 4c, CrO x /Al 2 O 3 The catalyst did not have any diffraction peaks for chromium species, indicating that the chromium species were highly dispersed on the alumina surface.
Example 2
Method for preparing hollow CrO simultaneously by detoxication and purification of chromium-containing waste salt x /Al 2 O 3 The preparation method of the catalyst comprises the following steps:
1) 4.3g of chromium-containing sodium sulfate (provided by silver river chemical Co., Ltd. of Sichuan province, chromium content is 1.02mg/g), 0.7g of aluminum sulfate and 0.7g of urea are dissolved in 70mL of water, and the mixture is magnetically stirred to be completely dissolved to obtain a yellow aqueous solution; at the moment, the concentration of chromium in the aqueous solution is 62.7mg/L, 32mg of sodium sulfite is added into the aqueous solution as a reducing agent, and magnetic stirring is continued for 15min to promote hexavalent chromium in the solution to be completely reduced into trivalent chromium, so that a green aqueous solution is obtained;
2) transferring the green aqueous solution obtained in the step 1) to a 100mL reaction kettle to ensure that the filling degree is 70%, and carrying out hydrothermal reaction; setting the reaction temperature to be 200 ℃ and the reaction time to be 1 h;
3) after the reaction is finished, naturally cooling to room temperature, and performing suction filtration to obtain filtrate and filter residue;
4) washing the filter residue with water for multiple times, and drying in an oven at 80 deg.C for 10h to obtain Cr (OH) 3 -an AlOOH precursor.
5) And (3) evaporating, concentrating, crystallizing and drying the filtrate to obtain the dechromized anhydrous sodium sulfate product, wherein the content of chromium in the dechromized anhydrous sodium sulfate product is lower than 0.001mg/g, and the product meets the standard requirement of industrial salt GBT/6009-2014.
6) The Cr (OH) obtained in the step 4) 3 Placing the AlOOH precursor in a muffle furnace, raising the temperature to 800 ℃ at the heating rate of 5 ℃/min, keeping the temperature for 2h, and naturally cooling to room temperature to obtain CrO x /Al 2 O 3 A catalyst.
7) CrO with high dispersion of chromium species prepared in step 6) and excellent anti-sintering performance x /Al 2 O 3 The catalyst is applied to the reaction of preparing low-carbon olefin by dehydrogenation of low-carbon alkane.
0.2g CrO x /Al 2 O 3 Catalyst C at volume ratio of 2/8 2 H 6 /N 2 The reaction is carried out for 6h at 590 ℃ in an atmosphere of 60mL/min, and the conversion rate of ethane is kept to be about 15 percent.
Example 3
Method for preparing hollow CrO simultaneously by detoxication and purification of chromium-containing waste salt x /Al 2 O 3 The preparation method of the catalyst comprises the following steps:
1) dissolving 21.5g of chromium-containing sodium sulfate (provided by Yinhe chemical Co., Ltd. of Sichuan province, chromium content is 1.02mg/g), 0.7g of aluminum sulfate and 0.7g of urea in 70mL of water, and magnetically stirring to completely dissolve the aluminum sulfate and the urea to obtain a yellow aqueous solution; at the moment, the concentration of chromium in the aqueous solution is 313.3mg/L, 0.15g of sodium sulfite is added into the aqueous solution as a reducing agent, and magnetic stirring is continued for 15min to promote hexavalent chromium in the solution to be completely reduced into trivalent chromium, so that a green aqueous solution is obtained;
2) transferring the green aqueous solution obtained in the step 1) to a 100mL reaction kettle to ensure that the filling degree is 70%, and carrying out hydrothermal reaction; setting the reaction temperature to be 120 ℃ and the reaction time to be 48 h;
3) after the reaction is finished, naturally cooling to room temperature, and performing suction filtration to obtain filtrate and filter residue;
4) washing the filter residue with water for multiple times, and drying in an oven at 80 deg.C for 10h to obtain Cr (OH) 3 -an AlOOH precursor;
5) evaporating, concentrating, crystallizing and drying the filtrate to obtain the dechromized anhydrous sodium sulfate, wherein the content of chromium in the dechromized anhydrous sodium sulfate product is lower than 0.001mg/g, and the product meets the standard requirement of industrial salt GBT/6009-;
6) the Cr (OH) obtained in the step 4) 3 Placing the AlOOH precursor in a muffle furnace, raising the temperature to 500 ℃ at the heating rate of 1 ℃/min, keeping the temperature for 2h, and naturally cooling to room temperature to obtain CrO x /Al 2 O 3 A catalyst;
7) CrO with high dispersion of chromium species prepared in step 6) and excellent anti-sintering performance x /Al 2 O 3 The catalyst is applied to the reaction of preparing low-carbon olefin by dehydrogenation of low-carbon alkane.
0.2g CrO x /Al 2 O 3 Catalyst C at volume ratio of 2/8 2 H 6 /N 2 The reaction is carried out for 6h at 590 ℃ in an atmosphere of (20mL/min), and the conversion rate of ethane is kept at about 23%.
Example 4
Method for preparing hollow CrO simultaneously by detoxication and purification of chromium-containing waste salt x /Al 2 O 3 The preparation method of the catalyst comprises the following steps:
1) dissolving 21.5g of chromium-containing sodium sulfate (provided by Yinhe chemical Co., Ltd. of Sichuan province, chromium content is 1.02mg/g), 0.7g of aluminum sulfate and 0.7g of urea in 70mL of water, and magnetically stirring to completely dissolve the aluminum sulfate and the urea to obtain a yellow aqueous solution; at the moment, the concentration of chromium in the aqueous solution is 313.3mg/L, 0.15g of sodium sulfite is added into the aqueous solution as a reducing agent, and magnetic stirring is continued for 15min to promote hexavalent chromium in the solution to be completely reduced into trivalent chromium, so that a green aqueous solution is obtained;
2) transferring the green aqueous solution obtained in the step 1) to a 100mL reaction kettle to ensure that the filling degree is 70%, and carrying out hydrothermal reaction; setting the reaction temperature to be 200 ℃ and the reaction time to be 1 h;
3) after the reaction is finished, naturally cooling to room temperature, and performing suction filtration to obtain filtrate and filter residue;
4) washing the filter residue with water for multiple times, and drying in an oven at 80 deg.C for 10h to obtain Cr (OH) 3 -an AlOOH precursor;
5) evaporating, concentrating, crystallizing and drying the filtrate to obtain an anhydrous sodium sulfate product after chromium removal, wherein the content of chromium in the anhydrous sodium sulfate product after chromium removal is lower than 0.001mg/g, and the product meets the standard requirement of industrial salt GBT/6009-2014;
6) cr (OH) obtained in the step 4) 3 Placing the AlOOH precursor in a muffle furnace, raising the temperature to 800 ℃ at a heating rate of 10 ℃/min, keeping the temperature for 2h, and naturally cooling to room temperature to obtain CrO x /Al 2 O 3 A catalyst;
7) CrO with high dispersion of chromium species prepared in step 6) and excellent anti-sintering performance x /Al 2 O 3 The catalyst is applied to the reaction of preparing low-carbon olefin by dehydrogenation of low-carbon alkane.
0.2g CrO x /Al 2 O 3 Catalyst C at volume ratio of 2/8 2 H 6 /N 2 The reaction is carried out for 6h at 590 ℃ in an atmosphere of 60mL/min, and the conversion rate of ethane is kept at about 23%.
Example 5
Method for preparing hollow CrO simultaneously by detoxication and purification of chromium-containing waste salt x /Al 2 O 3 The preparation method of the catalyst comprises the following steps:
1) dissolving 21.5g of chromium-containing sodium chloride (provided by silver river chemical Co., Ltd. of Sichuan province, chromium content is 1.18mg/g), 0.7g of aluminum chloride and 0.7g of urea in 70mL of water, and magnetically stirring to completely dissolve the aluminum chloride and the urea to obtain a yellow aqueous solution; at the moment, the concentration of chromium in the aqueous solution is 362.4mg/L, 0.1g of hydrazine hydrate is added into the aqueous solution as a reducing agent, and the magnetic stirring is continued for 15min to promote the hexavalent chromium in the solution to be completely reduced into trivalent chromium, so that a green aqueous solution is obtained;
2) transferring the green aqueous solution obtained in the step 1) to a 100mL reaction kettle to ensure that the filling degree is 70%, and carrying out hydrothermal reaction; setting the reaction temperature to be 120 ℃ and the reaction time to be 48 h;
3) after the reaction is finished, naturally cooling to room temperature, and performing suction filtration to obtain filtrate and filter residue;
4) washing the filter residue with water for multiple times, and drying in an oven at 80 deg.C for 10h to obtain Cr (OH) 3 -an AlOOH precursor;
5) evaporating, concentrating, crystallizing and drying the filtrate to obtain a dechromized anhydrous sodium chloride product, wherein the chromium content in the dechromized anhydrous sodium chloride product is lower than 0.001mg/g, and the product meets the standard requirement of industrial salt GB/T5462-2015;
6) the Cr (OH) obtained in the step 4) 3 Placing the AlOOH precursor in a muffle furnace, raising the temperature to 500 ℃ at the heating rate of 5 ℃/min, keeping the temperature for 2h, and naturally cooling to room temperature to obtain CrO x /Al 2 O 3 A catalyst;
7) CrO with high dispersion of chromium species prepared in step 6) and excellent anti-sintering performance x /Al 2 O 3 The catalyst is applied to the reaction of preparing low-carbon olefin by dehydrogenation of low-carbon alkane.
0.2g CrO x /Al 2 O 3 Catalyst C at volume ratio of 2/8 2 H 6 /N 2 The reaction is carried out for 6h at 590 ℃ and 750 ℃ in the atmosphere of (20mL/min), and the conversion rate of ethane is kept to be about 26 percent.
Example 6
Method for preparing hollow CrO simultaneously by detoxication and purification of chromium-containing waste salt x /Al 2 O 3 The preparation method of the catalyst comprises the following steps:
1) taking 21.5g of chromium-containing sodium chloride (provided by Sichuan silver river chemical Co., Ltd., chromium content is 1.18mg/g), 0.7g of aluminum chloride and 0.7g of urea to dissolve in 70mL of water, and stirring by magnetic force to completely dissolve the aluminum chloride and the urea to obtain a yellow aqueous solution; at the moment, the concentration of chromium in the aqueous solution is 362.4mg/L, 0.1g of hydrazine hydrate is added into the aqueous solution as a reducing agent, and the magnetic stirring is continued for 15min to promote the hexavalent chromium in the solution to be completely reduced into trivalent chromium, so that a green aqueous solution is obtained;
2) transferring the green aqueous solution obtained in the step 1) to a 100mL reaction kettle to ensure that the filling degree is 70%, and carrying out hydrothermal reaction; setting the reaction temperature to be 200 ℃ and the reaction time to be 1 h;
3) after the reaction is finished, naturally cooling to room temperature, and performing suction filtration to obtain filtrate and filter residue;
4) washing the filter residue with water for several timesThen placing the mixture in an oven to be dried for 10h at the temperature of 80 ℃ to obtain Cr (OH) 3 -an AlOOH precursor;
5) evaporating, concentrating, crystallizing and drying the filtrate to obtain a dechromized anhydrous sodium chloride product, wherein the product meets the standard requirement of industrial salt GB/T5462-2015 as shown in figure 5 d;
6) the Cr (OH) obtained in the step 4) 3 Placing the AlOOH precursor in a muffle furnace, raising the temperature to 800 ℃ at the heating rate of 5 ℃/min, keeping the temperature for 2h, and naturally cooling to room temperature to obtain CrO x /Al 2 O 3 The morphology and phase characterization results of the catalyst are shown in FIGS. 5 a-c.
The CrO can be seen from FIGS. 5a-c x /Al 2 O 3 Is a hollow flower-like structure composed of nanosheets, and only the diffraction peak of alumina is detected in fig. 5c, indicating that the chromium species are highly dispersed on the surface of the alumina.
Comparative example 1:
CrO x /Al 2 O 3 The preparation method of the catalyst comprises the following steps:
1) taking 21.5g of chromium-containing sodium chloride (provided by Sichuan silver river chemical Co., Ltd., chromium content is 1.18mg/g), 0.7g of aluminum chloride and 0.7g of urea to dissolve in 70mL of water, and stirring by magnetic force to completely dissolve the aluminum chloride and the urea to obtain a yellow aqueous solution; at the moment, the concentration of chromium in the aqueous solution is 362.4mg/L, 0.1g of hydrazine hydrate is added into the aqueous solution as a reducing agent, and the magnetic stirring is continued for 15min to promote the hexavalent chromium in the solution to be completely reduced into trivalent chromium, so that a green aqueous solution is obtained;
2) transferring the green aqueous solution obtained in the step 1) to a 100mL reaction kettle to ensure that the filling degree is 70%, and carrying out hydrothermal reaction; setting the reaction temperature to be 100 ℃ and the reaction time to be 48 h;
3) after the reaction is finished, naturally cooling to room temperature, and performing suction filtration to obtain filtrate and filter residue;
4) washing the filter residue with water for multiple times, and drying in an oven at 80 deg.C for 10h to obtain Cr (OH) 3 -an AlOOH precursor;
5) evaporating, concentrating, crystallizing and drying the filtrate, and finding that the evaporated sodium chloride still turns yellow, wherein the content of chromium in the sodium chloride is 0.86 mg/g;
6) in step 4) areResulting Cr (OH) 3 Placing the AlOOH precursor in a muffle furnace, raising the temperature to 800 ℃ at the heating rate of 5 ℃/min, keeping the temperature for 2h, and naturally cooling to room temperature to obtain CrO x /Al 2 O 3 A catalyst.
And (3) performance testing:
CrO prepared in example 1, example 6 and comparative example 1 are respectively x /Al 2 O 3 The catalyst is applied to the reaction of preparing low-carbon olefin by low-carbon alkane dehydrogenation, namely CrO x /Al 2 O 3 The catalyst amount was 0.2g, the reaction temperature was 590 ℃, the reaction time was 280min, the reaction gas composition was a mixed gas of ethane and nitrogen (volume ratio: 2/8), and the reaction gas flow rate was 60mL/min, the results are shown in FIG. 6.
As can be seen from FIG. 6, CrO prepared in example 1 was initially reacted x /Al 2 O 3 The ethane conversion of the catalyst is 25.6%, and after 280min of reaction, the ethane conversion is kept at 25.5%, and basically kept unchanged. Initial reaction CrO prepared in example 6 x /Al 2 O 3 The ethane conversion rate of the catalyst is 17.6 percent, and after 280min of reaction, CrO x /Al 2 O 3 The ethane conversion of the catalyst was maintained at 16.8%. And CrO prepared in comparative example 1 x /Al 2 O 3 The ethane conversion of the catalyst was 11.8% at the beginning of the reaction, and after 280min of reaction, the ethane conversion decreased to 4.8%.
Comparative example 2:
CrO x /Al 2 O 3 The preparation method of the catalyst comprises the following steps:
1) dissolving 21.5g of chromium-containing sodium chloride (provided by silver river chemical Co., Ltd. of Sichuan province, chromium content is 1.18mg/g), 0.7g of aluminum chloride and 0.7g of urea in 70mL of water, and magnetically stirring to completely dissolve the aluminum chloride and the urea to obtain a yellow aqueous solution; the concentration of chromium in the aqueous solution at this time was 528.6 mg/L.
2) The yellow aqueous solution obtained in 1) was transferred to a 100mL reaction vessel so that the degree of filling was 70%, and hydrothermal reaction was carried out. The reaction temperature was set at 200 ℃ and the reaction time was 1 h.
3) And after the reaction is finished, naturally cooling to room temperature, and performing suction filtration to obtain filtrate and filter residue.
4) Washing the filter residue with water for multiple times, and drying in an oven at 80 deg.C for 10h to obtain Cr (OH) 3 -an AlOOH precursor.
5) And (3) evaporating, concentrating, crystallizing and drying the filtrate to obtain evaporated sodium chloride, wherein the color of the evaporated sodium chloride is very close to that of the raw material chromium-containing sodium chloride, and the content of chromium in the evaporated sodium chloride is 1.16mg/g through testing.
6) The Cr (OH) obtained in the step 4) 3 Placing the AlOOH precursor in a muffle furnace, raising the temperature to 800 ℃ at the heating rate of 5 ℃/min, keeping the temperature for 2h, and naturally cooling to room temperature to obtain CrO x /Al 2 O 3 A catalyst.
7) The chromium species prepared in step 6) are highly dispersed and have CrO with excellent anti-sintering performance x /Al 2 O 3 The catalyst is applied to the reaction of preparing low-carbon olefin by dehydrogenation of low-carbon alkane.
0.2g CrO x /Al 2 O 3 Catalyst C at volume ratio of 2/8 2 H 6 /N 2 After reaction at 590 ℃ for 6h in an atmosphere of (60mL/min), CrO x /Al 2 O 3 The catalyst has little catalytic performance.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (10)
1. Method for preparing hollow CrO simultaneously by detoxication and purification of chromium-containing waste salt x /Al 2 O 3 A method of catalyzing, comprising the steps of:
(1) dissolving chromium-containing waste salt, aluminum salt and pore-forming agent in water to obtain aqueous solution; adding a reducing agent into the aqueous solution, and stirring to obtain a mixed solution;
(2) carrying out hydrothermal reaction on the mixed solution, cooling and carrying out suction filtration to obtain filtrate and filter residue;
(3) washing step (2) to obtainDrying the filter residue to obtain Cr (OH) 3 -an AlOOH precursor;
(4) heating, concentrating, crystallizing and drying the filtrate to obtain dechromized salt;
(5) cr (OH) obtained in the step (3) 3 Heating the AlOOH precursor to 500-800 ℃ at the heating rate of 1-10 ℃/min and roasting for 2-10 h to obtain hollow CrO x /Al 2 O 3 A catalyst.
2. The method of claim 1,
in the step (1), the reducing agent comprises at least one of sodium sulfite, ascorbic acid, hydrazine hydrate and sodium borohydride;
in the step (2), the hydrothermal reaction conditions are as follows: reacting for 1-48 h at 120-200 ℃.
3. The method of claim 1,
in the step (1), the chromium-containing waste salt comprises at least one of chromium-containing sodium sulfate, chromium-containing sodium bisulfate and chromium-containing sodium chloride;
in the step (1), the aluminum salt comprises at least one of aluminum sulfate, aluminum nitrate and aluminum chloride;
in the step (1), the pore-forming agent comprises at least one of thiourea, melamine, urea, citric acid and polyethylene glycol.
4. The method of claim 1,
in the step (1), the chromium-containing waste salt, the aluminum salt and the pore-forming agent are calculated according to the mass ratio of 1-25: 0.1-8: 0.5-15;
in the step (1), the chromium-containing waste salt and the reducing agent are calculated according to the mass ratio of 1-25: 0.032-0.15;
in the step (3), the drying conditions are as follows: drying for 8-12 h at 70-90 ℃.
5. The method of claim 4,
in the step (1), the chromium-containing waste salt, the aluminum salt and the pore-forming agent are calculated according to the mass ratio of 4.3-21.5: 0.7: 0.7;
in the step (1), the chromium-containing waste salt and the reducing agent are calculated according to the mass ratio of 4.3-21.5: 0.032-0.15;
in the step (3), the drying conditions are as follows: drying at 80 ℃ for 10 h.
6. The method for preparing hollow CrO simultaneously by detoxification, purification and simultaneous production of chromium-containing waste salt according to any one of claims 1 to 5 x /Al 2 O 3 Method for detoxifying chromium-containing waste salt and/or preparing CrO x /Al 2 O 3 Application in catalysts.
7. CrO x /Al 2 O 3 The catalyst is characterized by being prepared by the method of any one of claims 1 to 5.
8. CrO as claimed in claim 7 x /Al 2 O 3 Use of a catalyst for the dehydrogenation of alkanes to olefins.
9. Use of CrO as defined in claim 7 x /Al 2 O 3 A method for preparing olefin by dehydrogenating alkane with catalyst, which is characterized in that the method comprises the step of using CrO as defined in claim 7 x /Al 2 O 3 And (3) carrying out high-temperature dehydrogenation reaction on the catalyst in a mixed atmosphere of alkane and nitrogen.
10. The method of claim 9,
the alkane and the nitrogen are calculated according to the volume ratio of 2: 8;
the high-temperature dehydrogenation reaction is carried out for 6 hours at the temperature of 500-750 ℃.
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| CN115069234B (en) | 2023-09-29 |
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