Vanadium-chromium composite oxide material as well as preparation method and application thereof
The formation of porous hollow microsphere-shaped vanadium-chromium composite oxide material through nanoparticles stacking solves the problems of low crystallinity and small specific surface area of existing materials, and achieves efficient catalytic ammonia oxidation reaction, which significantly improves the reaction activity and selectivity.
Patent Information
- Application Number
- CN202510214713.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-26
- Publication Date
- 2025-06-24
AI Technical Summary
The existing vanadium chromium composite oxide materials have low crystallinity, irregular morphology, and small specific surface area, which limits their application range.
Porous hollow microsphere-shaped vanadium-chromium composite oxide material is formed by stacking block or sheet-shaped nanoparticles, and prepared by solvothermal reaction and calcining processes to form porous hollow microspheres of uniform size.
The prepared porous hollow microspherical vanadium chromium composite oxide material has a high catalytic effect. When used to catalyze ammonia oxidation reaction, the reaction temperature is reduced, the reaction activity and product yield are significantly improved, and the selectivity is also greatly improved.
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Figure CN120189936A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the fields of materials and chemical engineering, and particularly relates to a vanadium-chromium composite oxide material, a preparation method thereof, and an application thereof. Background Art
[0002] Vanadium-chromium composite oxide is an important inorganic functional material in the fields of materials and chemical engineering, and can be applied to fields such as catalysis, super proton conductors, capacitor materials, sensors, etc. As a catalytic material, it has good catalytic performance; as a battery material, it can be used to prepare excellent capacitor devices, sodium battery, and lithium battery electrode materials, which can improve the electrochemical performance.
[0003] There are various main methods for synthesizing vanadium-chromium composite oxide. For example, through the co-precipitation method, ammonium metavanadate is placed in water, and chromium nitrate is added during stirring, and the precipitate is placed in a muffle furnace for activation to obtain CrVO4 (L. Shreenivasa, R. Yogeeshwari, R. Viswanatha, Ionics 27(1)(2021)39 - 48.); or it is synthesized by the spray drying method. A certain amount of vanadium pentoxide and chromium trioxide are dissolved in an oxalic acid solution and diluted with a silica gel solution, and CrVO4 is prepared by a spray dryer (C. Du, Y. Huang, W. Tang, Research on Chemical Intermediates 49(12)(2023)5361 - 5374.); it can also be obtained by a solid-state reaction method. Vanadium pentoxide and chromium trioxide are ground evenly and then directly calcined to obtain CrVO4 (G. Bera, A. Mishra, P. Mal, The Journal of Physical Chemistry C 122(37)(2018)21140 - 21150.). The materials prepared by these methods have low crystallinity, irregular morphologies, and small specific surface areas, which result in few surface active centers of the microparticles, small contact surfaces for chemical reactions, and low reaction activity, thus limiting its application range. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to provide a porous hollow micron-sized spherical vanadium-chromium composite oxide VCr x M y O z material, which is formed by stacking blocky or flaky nanoparticles, has uniform size, and the diameter of the microspheres is 5 - 100 μm. The porous hollow micron-sized spherical vanadium-chromium composite oxide material has good catalytic effect as a catalyst for catalytic ammonia oxidation reaction. The porous hollow microsphere material of the vanadium-chromium composite oxide of the present invention is prepared by the following method:
[0005] Place the active component source and the promoter in a pressure vessel, add water as the solvent and mix evenly. After sealing, heat it to 120 - 300 °C and carry out a solvothermal reaction for 2 - 200 hours. The product is filtered, washed and vacuum dried to obtain a precursor; the active component source includes a vanadium source and a chromium source.
[0006] Calcine the precursor at a temperature of 300 - 800 °C for 0.1 - 10 hours and cool it to room temperature to obtain a porous hollow micron-sized spherical vanadium-chromium composite oxide.
[0007] The vanadium source is vanadium oxide and / or vanadium salt, and the chromium source is chromium oxide and / or chromium salt.
[0008] The active component source further includes a third component source, and the third component source is one of a titanium source, a molybdenum source, a tungsten source, a boron source, an iron source, a cobalt source, a nickel source, a copper source, a zinc source, an antimony source, a bismuth source, an alkali metal source and an alkaline earth metal source.
[0009] The composition of the vanadium-chromium composite oxide is VCr x M y O z , where x = 0.1 - 3, which is the atomic molar ratio of chromium to vanadium; y = 0 - 1.5, which is the atomic molar ratio of the third component to vanadium; z is determined according to the atomic valence state.
[0010] The vanadium oxides include but are not limited to at least one of V2O5, V2O4 and V2O3, and the vanadium salts include but are not limited to at least one of NH4VO3, VOSO4 and VOCl2; the chromium oxides are at least one of Cr2O3 and CrO3; the chromium salts are at least one of CrCl3, Cr(NO3)3 and (NH4)2Cr2O7; the titanium source is TiCl4, TiCl3 or TiO2, etc.; the molybdenum source is MoO3, (NH4)6Mo7O 24 etc.; the tungsten source is WO3, H2WO4, WOCl4, (NH4) 10 W 12 O 41etc.; the boron source is H3BO3, B2O3, etc.; the iron source is FeCl3, Fe2O3, Fe3O4, Fe(NO3)3·9H2O, Fe(OAc)2, FeC2O4·2H2O or Fe2(C2O4)3·6H2O, etc.; the cobalt source is Co(OAc)2, Co(NO3)2·6H2O, Co3O4 or CoCl2, etc.; the nickel source is NiCl2·6H2O or Ni(NO3)2·6H2O, etc.; the copper source is CuO, CuCl2, Cu(OAc)2, Cu(NO3)2, etc.; the zinc source is ZnO, ZnCl2, Zn(OAc)2, Zn(NO3)2, etc.; the antimony source is Sb2O3, Sb2O5, H3SbO4, Sb(NO3)3, SbCl3, SbCl5, (SbO)2SO4, antimony acetate, ammonium oxalatoantimonate, potassium antimonyl tartrate, sodium antimonyl tartrate or tartaric acid antimonate, etc.; the bismuth source is Bi(NO3)3, BiCl3, Bi2O3, etc.; the alkali metal source is its oxide, hydroxide, nitrate, carbonate, oxalate, sulfate, chloride, etc.; the alkaline earth metal source is its oxide, hydroxide, nitrate, carbonate, oxalate, sulfate, chloride, etc.
[0011] The promoter is an amino acid compound, including but not limited to α-, β-, γ- amino acids, etc.; the molar ratio of the promoter to vanadium is 0.1 - 20.
[0012] The pressure vessel is an autoclave or a pressure-resistant reactor.
[0013] The solvothermal reaction temperature is 150 - 250 °C, and the time is 6 - 100 hours.
[0014] The porous hollow microspherical vanadium-chromium composite oxide provided by the present invention can be used for catalytic ammoxidation of methylaromatics to prepare aromatic nitriles.
[0015] The methylaromatics include toluene, halogenated toluene, methoxytoluene, hydroxytoluene, nitrotoluene, cyanotoluene, aminotoluene, xylene, methylpyridine, methylpyrazine or methylpyrimidine.
[0016] The present invention uses vanadium and chromium compounds and compounds of other elements as raw materials, amino acid compounds as auxiliary reagents, and water as a solvent to carry out a solvothermal reaction in a pressure vessel. The prepared binary or ternary vanadium-chromium composite oxide can self-assemble to form a porous hollow micron-spherical structure. The particle size distribution of the microsphere material is uniform, the specific surface area is large, the catalyst preparation method is simple, the raw materials are easy to obtain, the cost is low, and it is suitable for large-scale preparation. When the vanadium-chromium composite oxide with this structure is used in the ammoxidation reaction of methylaromatic hydrocarbons to prepare aromatic nitriles, the ammoxidation reaction temperature is 300-450 °C. Compared with other vanadium-based catalysts, not only is the reaction temperature significantly reduced, but also the reaction activity and product yield are significantly increased by 5-50%, and the selectivity is also greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 It is a scanning electron microscope image (5-micron scale) of the porous hollow micron-spherical CrVO4 precursor obtained in the present invention.
[0018] Figure 2 It is a scanning electron microscope image (5-micron scale) of the porous hollow micron-spherical CrVO4 obtained in the present invention.
[0019] Figure 3 It is a scanning electron microscope image (2-micron scale) of the porous hollow micron-spherical CrVO4 obtained in the present invention.
[0020] Figure 4 It is a scanning electron microscope image (300-nanometer scale) of the porous hollow micron-spherical CrVO4 obtained in the present invention.
[0021] Figure 5 It is an XRD pattern (PDF#51-0031) of the porous hollow micron-spherical CrVO4 obtained in the present invention. DETAILED DESCRIPTION OF THE INVENTION
[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0023] Example 1
[0024] According to the molar ratio of V:Cr:leucine = 1:1:1, 5.0g of V2O5, CrO3 and leucine were weighed and placed in a beaker, and then 8.90g of tartaric acid and 80ml of distilled water were added and stirred and mixed thoroughly. The reaction was heated in a water bath until no bubbles were generated. The obtained dark blue solution was transferred to a hydrothermal reactor lined with polytetrafluoroethylene with a volume of 100ml. After sealing, the reactor was placed in a resistance furnace and heated to 220℃. After constant temperature hydrothermal treatment for 36h, it was naturally cooled to room temperature. The product in the reactor was filtered and washed repeatedly with distilled water and ethanol, and then vacuum dried at 70℃ for 12h to obtain an amorphous spherical CrVO4 precursor. The precursor was calcined in a muffle furnace at 550℃ for 3h to obtain porous hollow microspheres assembled from nano-CrVO4.
[0025] Figure 1 The scanning electron microscope images of the CrVO4 precursor material obtained in this embodiment at a scale of 5 microns show that the precursor material is a sphere with a diameter of about 5 microns. Figure 2 , Figure 3 and Figure 4 The scanning electron microscope images of the CrVO4 porous hollow microspheres obtained in this embodiment at scales of 5, 2, and 0.3 microns respectively show that the material is a porous microsphere with a regular structure and roughly uniform size assembled from nanoparticles. The size of the microspheres remains at around 5 microns, which is roughly the same as that of the precursor, and a hollow structure appears with obvious holes on the surface.
[0026] Figure 5 The XRD pattern of the CrVO4 porous hollow microspheres obtained in this example is basically consistent with that of the standard card.
[0027] Example 2
[0028] This embodiment is a comparative example.
[0029] The preparation method and treatment method of the catalyst are the same as those in Example 1, except that no leucine additive is added. The catalyst precursor obtained is amorphous. CrVO4 is obtained after calcination at 550°C for 3h. It does not generate a spherical shape and has poor dispersion. The material has no complete morphology, and the particle size of the particles is different and the specific surface area is small.
[0030] Example 3
[0031] According to the molar ratio of vanadium, chromium, molybdenum and additives of 1:1.5:0.1:0.5, weigh 10.0g of NH4VO3, Cr2O3, (NH4)6Mo7O 24and β-aminobutyric acid were placed in a hydrothermal reactor with a PTFE liner having a volume of 100 ml. Then 80 ml of water was added and the mixture was stirred well until evenly mixed. After sealing, the reactor was placed in an electric resistance furnace and heated to 180 °C. After isothermal hydrothermal treatment for 72 h, it was naturally cooled to room temperature. The product in the reactor was filtered and repeatedly washed with distilled water and ethanol respectively, and then dried in vacuum at 70 °C for 8 h to obtain an amorphous VCrMo composite oxide precursor. The precursor was calcined in an electric resistance furnace at 600 °C for 5 h to obtain VCr 1.5 Mo 0.1 O 5.05 composite oxide porous hollow microspheres.
[0032] Example 4
[0033] According to the molar ratio of vanadium, chromium, iron and the additive of 1:2:0.3:3, 8.0 g of VOCl2, Cr(NO)3, Fe(NO)3 and arginine were weighed and placed in a hydrothermal reactor with a PTFE liner having a volume of 100 ml. Then 80 ml of water was added and the mixture was stirred well until evenly mixed. After sealing, the reactor was placed in an electric resistance furnace and heated to 160 °C. After isothermal hydrothermal treatment for 96 h, it was naturally cooled to room temperature. The product in the reactor was filtered and repeatedly washed with distilled water and ethanol respectively, and then dried in vacuum at 60 °C for 10 h to obtain an amorphous VCrFe composite oxide precursor. The precursor was calcined in an electric resistance furnace at 650 °C for 2 h to obtain VCr2Fe 0.3 O 5.95 composite oxide porous hollow microspheres.
[0034] Example 5
[0035] According to the molar ratio of vanadium, chromium, calcium and the additive of 1:1:0.2:0.6, 6.0 g of V2O3, (NH4)2Cr2O7, Ca(NO3)2 and serine were weighed and placed in a hydrothermal reactor with a PTFE liner having a volume of 100 ml. Then 80 ml of distilled water was added and the mixture was stirred well until evenly mixed. After sealing, the reactor was placed in an electric resistance furnace and heated to 220 °C. After isothermal hydrothermal treatment for 36 h, it was naturally cooled to room temperature. The product in the reactor was filtered and repeatedly washed with distilled water and ethanol respectively, and then dried in vacuum at 80 °C for 10 h to obtain an amorphous VCrCa composite oxide precursor. The precursor was calcined in an electric resistance furnace at 600 °C for 3 h to obtain VCrCa 0.2 O 4.2 composite oxide porous hollow microspheres.
[0036] Example 6
[0037] In a quartz tube fixed-bed reactor with an inner diameter of 30 mm, 20 g of the CrVO4 porous hollow microspheres prepared in Example 1 were loaded. o-Chlorotoluene, ammonia, and air were preheated and mixed in a molar ratio of 1:3:15 and then passed through the catalyst bed for reaction. The reaction temperature was 380 °C. After 6 hours of reaction, the conversion rate of o-chlorotoluene was 98.3%, and the molar yield of o-chlorobenzonitrile was 88.2%.
[0038] Using the CrVO4 prepared in Example 2 as the catalyst, when the reaction temperature was 390 °C, the conversion rate of o-chlorotoluene was 93.6%, and the molar yield of o-chlorobenzonitrile was 75.1%.
[0039] Example 7
[0040] In a quartz tube fixed-bed reactor with an inner diameter of 30 mm, 10 g of the VCr 1.5 Mo 0.1 O 5.05 composite oxide porous hollow microspheres prepared in Example 3 were loaded. o-Chlorotoluene, ammonia, and air were preheated and mixed in a molar ratio of 1:3:15 and then passed through the catalyst bed for reaction. The reaction temperature was 380 °C. After 8 hours of reaction, the conversion rate of o-chlorotoluene was 99.4%, and the molar yield of o-chlorobenzonitrile was 91.5%.
[0041] Example 8
[0042] In a quartz tube fixed-bed reactor with an inner diameter of 30 mm, 10 g of the VCr 1.5 Mo 0.1 O 5.05 composite oxide porous hollow microspheres prepared in Example 3 were loaded. 4-Hydroxytoluene, ammonia, and air were preheated and mixed in a molar ratio of 1:5:20 and then passed through the catalyst bed for reaction. The reaction temperature was 350 °C. After 8 hours of reaction, the conversion rate of 4-hydroxytoluene was 91.4%, and the molar yield of 4-hydroxybenzonitrile was 79.5%.
[0043] Using the CrVO4 prepared in Example 2 as the catalyst, when the reaction temperature was 360 °C, after 8 hours of reaction, the conversion rate of 4-hydroxytoluene was 90.8%, and the molar yield of 4-hydroxybenzonitrile was 55.7%.
[0044] Example 9
[0045] In a quartz tube fixed-bed reactor with an inner diameter of 30 mm, 15 g of the VCr2Fe 0.3 O 5.95 composite oxide porous hollow microspheres prepared in Example 4 were loaded. m-Xylene, ammonia, and air were preheated and mixed in a molar ratio of 1:4:15 and then passed through the catalyst bed for reaction. The reaction temperature was 390 °C. After 8 hours of reaction, the conversion rate of m-xylene was 98.2%, and the molar yield of m-phthalonitrile was 93.1%.
[0046] Using the CrVO4 prepared in Example 2 as the catalyst, when the reaction temperature was 400 °C and the reaction was carried out for 8 hours, the conversion rate of m-xylene was 98.9%, and the molar yield of isophthalonitrile was 70.6%.
[0047] Example 10
[0048] 10 g of the VCrCa 0.2 O 4.2 composite oxide porous hollow microspheres prepared in Example 5 were loaded into a quartz tube fixed-bed reactor with an inner diameter of 30 mm. p-Bromotoluene, ammonia and air were preheated and mixed in a molar ratio of 1:3:18 and then passed through the catalyst bed for reaction at a reaction temperature of 350 °C. After the reaction for 8 hours, the conversion rate of p-bromotoluene was 95.7%, and the molar yield of p-bromobenzonitrile was 91.4%.
[0049] Using the CrVO4 prepared in Example 2 as the catalyst, when the reaction temperature was 380 °C and the reaction was carried out for 8 hours, the conversion rate of p-bromotoluene was 97.3%, and the molar yield of p-bromobenzonitrile was 82.0%.
Claims
1. A vanadium-chromium composite oxide material, characterized in that: The composition of the composite oxide is VCr x M y O z , wherein M is one of Ti, Mo, W, B, Fe, Co, Ni, Cu, Zn, Sb, Bi, alkali metal or alkaline earth metal; 0.1≤x≤3, which is the atomic molar ratio of chromium to vanadium; 0≤y≤1.5, which is the atomic molar ratio of M to vanadium; z depends on the atomic valence state; the composite oxide material is a porous hollow microsphere formed by assembling block or sheet nanoparticles, and the diameter of the microsphere is 1-100 μm.
2. A method for preparing a vanadium-chromium composite oxide material, characterized in that: The method comprises the following steps: 1) placing an active component source and an auxiliary agent in a pressure vessel, adding water as a solvent and mixing evenly, sealing and heating to 120-300° C., performing a solvent thermal reaction for 2-200 hours, filtering, washing, and vacuum drying the product to obtain a precursor; the active component source includes a vanadium source and a chromium source; 2) calcining the precursor at 300-800° C. for 0.1-10 hours and cooling to room temperature to obtain porous hollow micron-spherical vanadium-chromium composite oxide.
3. The method for preparing the vanadium-chromium composite oxide material according to claim 2, characterized in that: The vanadium source is vanadium oxide and / or vanadium salt, and the chromium source is chromium oxide and / or salt.
4. The method for preparing the vanadium-chromium composite oxide material according to claim 2, characterized in that: The active component source also includes a third component source, which is one of a titanium source, a molybdenum source, a tungsten source, a boron source, an iron source, a cobalt source, a nickel source, a copper source, a zinc source, an antimony source, a bismuth source, an alkali metal source and an alkaline earth metal source; the composition of the vanadium-chromium composite oxide is VCr x M y O z , the 0.1≤x≤3 is the atomic molar ratio of chromium to vanadium; 0<y≤1.5 is the atomic molar ratio of the third component to vanadium; z is determined according to the atomic valence state.
5. The method for preparing the vanadium-chromium composite oxide material according to claim 2 or 4, characterized in that: The vanadium oxides include but are not limited to at least one of V2O5, V2O4 and V2O3; the vanadium salts include but are not limited to at least one of NH4VO3, VOSO4 and VOCl2; the chromium oxides include but are not limited to at least one of Cr2O3 and CrO3; the chromium salts include but are not limited to at least one of CrCl3, Cr(NO3)3 and (NH4)2Cr2O7.
6. The method for preparing the vanadium-chromium composite oxide material according to claim 4, characterized in that: The titanium source is TiCl4, TiCl3 or TiO2; the molybdenum source is MoO3 or (NH4)6Mo7O 24 ; The tungsten source is WO3, H2WO4, WOCl4, or (NH4) 10 W 12 O 41 ; The boron source is H3BO3 or B2O3; the iron source is FeCl3, Fe2O3, Fe3O4, Fe(NO3)3·9H2O, Fe(OAc)2, FeC2O4·2H2O or Fe2(C2O4)3·6H2O; the cobalt source is Co(OAc)2, Co(NO3)2·6H2O, Co3O4 or CoCl2; the nickel source is NiCl2·6H2O or Ni(NO3)2·6H2O; the copper source is CuO, CuCl2, Cu(OAc)2 or Cu( NO3)2; the zinc source is ZnO, ZnCl2, Zn(OAc)2 or Zn(NO3)2; the antimony source is Sb2O3, Sb2O5, H3SbO4, Sb(NO3)3, SbCl3, SbCl5, (SbO)2SO4, antimony acetate, ammonium antimony oxalate, potassium antimony tartrate, sodium antimony tartrate or antimony tartrate; the bismuth source is Bi(NO3)3, BiCl3 or Bi2O3; the alkali metal source or alkaline earth metal source is its oxide, hydroxide, nitrate, carbonate, oxalate, sulfate or chloride.
7. The method for preparing the vanadium-chromium composite oxide material according to claim 2 or 4, characterized in that: The auxiliary agent is an amino acid compound, including but not limited to α-amino acid, β-amino acid and γ-amino acid; the molar ratio of the auxiliary agent to vanadium is 0.1-20.
8. The method for preparing the vanadium-chromium composite oxide material according to claim 2 or 4, characterized in that: The solvent thermal reaction temperature is 150-250° C. and the reaction time is 6-100 hours.
9. Use of the vanadium-chromium composite oxide material according to claim 1 in catalyzing the ammoxidation reaction of methyl aromatic hydrocarbons to prepare aromatic nitriles.
10. The use according to claim 9, characterized in that: The methyl aromatic hydrocarbons include toluene, halogenated toluene, methoxytoluene, hydroxytoluene, nitrotoluene, cyanotoluene, aminotoluene, xylene, picoline, methylpyrazine and methylpyrimidine.