Supported TEMPO catalyst as well as preparation method and application thereof
By introducing halogen functional groups and quaternary ammonium salt components on the surface of the molecular sieve, the pore structure of the supported TEMPO catalyst is optimized, the problem of low mass transfer efficiency is solved, efficient catalytic activity and stability are achieved, and the production process is simplified.
Patent Information
- Application Number
- CN202510409711.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-02
- Publication Date
- 2025-07-04
AI Technical Summary
The mass transfer efficiency of the supported TEMPO catalyst is low, resulting in a reduced catalytic efficiency, and the modification method is complex and the effect is unstable.
A silane coupling agent is used to introduce halogen as active functional group on the surface of the molecular sieve, and combined with quaternary ammonium salt as active component to optimize the channel structure of the molecular sieve and enhance the stability and mass transfer efficiency of the catalyst.
It improves the overall stability and mass transfer efficiency of the catalyst, enhances catalytic activity and selectivity, simplifies the production process, reduces costs, and realizes the recyclable use of the catalyst.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of catalyst preparation, and particularly relates to a supported TEMPO catalyst, a preparation method thereof, and an application thereof. Background Art
[0002] The TEMPO catalyst, namely 2,2,6,6-tetramethylpiperidinooxy, is a very effective oxidation catalyst that can oxidize primary alcohols and secondary alcohols into the desired carbonyl compounds - aldehydes and ketones. This reaction has wide applications in organic synthesis and the fine chemicals industry.
[0003] The supported TEMPO catalyst forms a composite catalyst system by loading small molecule TEMPO catalysts on polymers, inorganic materials or other carriers. This loading method retains the high activity and high selectivity of the TEMPO catalyst. The catalyst is easy to separate and can be reused, reducing costs and improving product quality. The selection and modification of the carrier in the supported TEMPO catalyst have a significant impact on the performance and application scope of the catalyst.
[0004] Properties of the carrier such as surface area, pore size, pore distribution, etc. will directly affect the activity, selectivity and stability of the supported TEMPO catalyst. Characteristics such as the mechanical strength, density, and thermal stability of the carrier also determine the applicability and durability of the catalyst under different reaction conditions. Through modification, the surface properties, pore structure, etc. of the carrier can be adjusted to better meet the requirements of TEMPO loading and catalytic reactions. Modification can also introduce new functional groups or active sites, thereby enhancing the activity or selectivity of the catalyst.
[0005] However, if the interaction between the carrier and the active component in the supported TEMPO catalyst is too strong, the movement of the active component will be restricted, thereby reducing the mass transfer efficiency; the properties of the carrier surface, such as hydrophilicity, hydrophobicity, charge distribution, etc. will also affect the adsorption and desorption processes of reactants on the carrier surface, and thus affect the mass transfer rate, resulting in the problem of reduced catalytic efficiency. Therefore, in the field of supported TEMPO catalysts, there are still defects and challenges such as limited selection range, difficult property matching, complex modification methods and unstable effects. Summary of the Invention
[0006] To solve the problem of low mass transfer efficiency of the supported TEMPO catalyst, the present invention provides a supported TEMPO catalyst, a preparation method thereof, and an application thereof.
[0007] The technical solution of the present invention:
[0008] A supported TEMPO catalyst uses a quaternary ammonium salt with the following structural formula as the active component:
[0009] R1 and R2 are alkyl or benzyl; R3 is n is from 1 to 4; X is chlorine, bromine or iodine; using a functionalized molecular sieve as a carrier, the TEMPO loading is 0.2 to 0.8 mmol / g.
[0010] A preparation method of a supported TEMPO catalyst, comprising the following steps:
[0011] Step 1, preparing a functionalized molecular sieve: refluxing a silane coupling agent and a molecular sieve in an organic solvent, cooling, filtering to collect the filter residue, washing the filter residue thoroughly and drying to obtain a functionalized molecular sieve;
[0012] Step 2, mixing amino TEMPO, a first solvent, a base and an alkyl halide or benzyl halide, heating and refluxing under nitrogen protection, washing the obtained reaction system successively with water, rotary evaporating the solvent and extracting with n-hexane to obtain an organic phase; after purification of the obtained organic phase, 2,2,6,6-tetramethyl-4-(dialkylamino)-1-piperidinyloxy free radical or 2,2,6,6-tetramethyl-4-(dibenzylamino)-1-piperidinyloxy free radical is obtained;
[0013] Step 3, mixing the functionalized molecular sieve obtained in Step 1, a second solvent and the 2,2,6,6-tetramethyl-4-(dialkylamino)-1-piperidinyloxy free radical or 2,2,6,6-tetramethyl-4-(dibenzylamino)-1-piperidinyloxy free radical obtained in Step 2, adding a nucleophilic reaction catalyst, heating and stirring for reflux reaction, cooling, filtering to collect the filter residue, washing thoroughly and drying to obtain a supported TEMPO catalyst.
[0014] Further, the mass ratio of the silane coupling agent, the molecular sieve and the organic solvent in Step 1 is 1:1:20, and the silane coupling agent is a silane coupling agent with a halogen as an active functional group.
[0015] Further, the silane coupling agent in Step 1 is 3-chloropropyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltriethoxysilane or 3-chloropropylmethyldiethoxysilane; the pore diameter of the molecular sieve is 2 to 60 nm, the particle size is 40 to 200 nm, and the specific surface area is 200 - 1700 m 2 / g; the organic solvent is toluene.
[0016] Further, the reflux reaction temperature in Step 1 is 70 to 110 °C, and the time is 6 to 24 h; the washing is successively washing with water, ethanol and dichloromethane, and the drying is drying at 60 to 120 °C for 6 to 8 h.
[0017] Furthermore, the mass ratio of the amino TEMPO to the first solvent in step two is 1:2 to 20, the first solvent is acetonitrile or tetrahydrofuran, the molar ratio of the amino TEMPO to the base is 1:0.7 to 2, the base is anhydrous potassium carbonate, sodium hydroxide or sodium tert-butoxide, the molar ratio of the amino TEMPO to the haloalkane or benzyl halide is 1:3.5 to 5, the haloalkane or benzyl halide is a C1-C16 normal or isomeric haloalkane, and the benzyl halide is benzyl chloride, benzyl bromide or benzyl iodide.
[0018] Furthermore, the temperature of the heating reflux in step two is 60 to 100 °C, and the time is 6 to 24 h.
[0019] Furthermore, the mass ratio of the functionalized molecular sieve to the second solvent in step three is 1:20 to 50, the second solvent is acetonitrile, acetone, benzene or toluene; the mass ratio of the functionalized molecular sieve to 2,2,6,6-tetramethyl-4-(dialkylamino)-1-piperidinyloxy radical or 2,2,6,6-tetramethyl-4-(dibenzylamino)-1-piperidinyloxy radical is 1:0.5 to 2; the mass ratio of the functionalized molecular sieve to the nucleophilic reaction catalyst is 1:0.01 to 0.2, and the nucleophilic reaction catalyst is DMAP.
[0020] Furthermore, the temperature of the heating and stirring reflux in step three is 70 to 120 °C, and the time is 10 to 20 h.
[0021] Application of a supported TEMPO catalyst in catalytic selective oxidation of alcohol to aldehyde or ketone.
[0022] Advantages of the present invention:
[0023] In the present invention, a silane coupling agent is used to introduce halogen as an active functional group on the surface of the molecular sieve. Halogen has a large electronegativity and electrophilicity. When halogen contacts the quaternary ammonium salt structure, a strong electronic interaction can be formed between them. This interaction helps to stabilize the quaternary ammonium salt structure and prevent its decomposition or detachment during the catalytic process, thereby enhancing the overall stability of the catalyst. The introduction of halogen can change the pore structure of the molecular sieve carrier, making it more conducive to the diffusion of reactants and the discharge of products. This optimization of the pore structure can reduce the mass transfer resistance and improve the mass transfer efficiency. As an active functional group, halogen can selectively interact with specific reactants or intermediates. This interaction can enhance the affinity between the catalyst and the reactants, making the reactants more easily adsorbed on the catalyst surface and participate in the catalytic reaction. This enhanced interaction helps to increase the rate and efficiency of the catalytic reaction, thereby further improving the mass transfer efficiency.
[0024] The present invention introduces quaternary ammonium salts into the supported TEMPO catalyst. By virtue of the cationic characteristics of the quaternary ammonium salts, electrostatic or hydrogen bond interactions occur with the anions or polar parts of the oxidant, thereby enhancing the binding strength between the catalyst and the active component of the oxidant. This enhanced interaction helps to improve the transfer efficiency of ClO - from the aqueous phase to the organic phase, increase the surface roughness or hydrophilicity, thus improving the interaction between the catalyst and the solvent, and can effectively improve its mass transfer efficiency in the Anelli oxidation system, thereby enhancing its catalytic activity. The supported type can also be used in a fixed-bed reaction device to achieve the continuous oxidation of fatty alcohols or benzyl alcohols.
[0025] The supported TEMPO catalyst prepared in the present invention has a specific surface area of the catalyst greater than 200 m 2 / g, has strong solvent resistance performance and cycle stability. After being reused 5 times, the catalytic effect does not decrease significantly. When the supported TEMPO catalyst prepared in the present invention is used for the selective oxidation of alcohols to aldehydes or ketones, it has high catalytic activity and high selectivity. The catalyst can be separated by filtration and can be recycled. The preparation method of the supported TEMPO catalyst of the present invention simplifies the production process, reduces costs, and is beneficial to environmental protection at the same time. Description of the Drawings
[0026] Figure 1 It is the infrared spectrogram of the supported TEMPO catalyst in Example 1 and the functionalized molecular sieve before loading;
[0027] Figure 2 It is the thermogravimetric curve of the supported TEMPO catalyst in Example 1 and the functionalized molecular sieve before loading. Detailed Embodiments
[0028] The technical solutions of the present invention will be further described below in conjunction with the embodiments, but are not limited thereto. Any modification or equivalent replacement of the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention shall be covered within the protection scope of the present invention. For the process equipment or devices not specifically noted in the following embodiments, conventional equipment or devices in the art are used. If not specifically specified, the raw materials used in the embodiments of the present invention can be obtained commercially; if not specifically specified, the technical means used in the embodiments of the present invention are all conventional means well-known to those skilled in the art.
[0029] Example 1
[0030] This example provides a preparation method of a supported TEMPO catalyst, including the following steps:
[0031] Step 1: Prepare a functionalized molecular sieve:
[0032] 5.0 g of molecular sieve with an average particle size of 20 nm, a specific surface area of 780 m 2 / g, and a pore size of 10 nm was added to the reaction flask, 5.0 g of 3-chloropropyltriethoxysilane and 100.0 g of toluene were added, and the mixture was refluxed at 110 °C for 12 h. After cooling, the filtrate was collected by suction filtration. The filter residue was washed thoroughly with water, ethanol, and dichloromethane in sequence, and dried at 80 °C for 8 h to obtain the functionalized molecular sieve;
[0033] Step 2: 5.03 g of amino TEMPO was added to a 100 mL reaction flask, 50 g of acetonitrile was added, 4.05 g of anhydrous potassium carbonate and 21.49 g of n-butyl iodide were added to the resulting system. Under nitrogen protection, the mixture was heated to 80 °C and refluxed for 10 h. The resulting reaction system was washed with water, rotary-evaporated to remove acetonitrile, and extracted with n-hexane to obtain the organic phase. The obtained organic phase was purified by column chromatography to obtain 6.76 g of a red oily liquid, which was 2,2,6,6-tetramethyl-4-(N,N-dibutyl)amino-1-piperidinyloxy free radical;
[0034] Step 3: 7.26 g of the functionalized molecular sieve obtained in Step 1 was added to a 250 mL reaction flask, 70 g of acetonitrile was added, 3.0 g of 2,2,6,6-tetramethyl-4-(N,N-dibutyl)amino-1-piperidinyloxy free radical obtained in Step 2 was added, 0.6 g of the nucleophilic reaction catalyst DMAP (4-dimethylaminopyridine) was added, and the mixture was heated to 80 °C and stirred under reflux for 16 h. After cooling, the filtrate was collected by suction filtration. The filter residue was washed thoroughly with acetonitrile, water, acetonitrile, and dichloromethane in sequence, and 8.04 g of a supported TEMPO catalyst containing a quaternary ammonium salt structure was obtained after drying.
[0035] In this example, the structural formula of the quaternary ammonium salt is:
[0036] R1 and R2 are n-butyl groups; R3 is n-propyl, X is chlorine; with the functionalized molecular sieve as the carrier, the TEMPO loading is 0.39 mmol / g.
[0037] The catalytic performance of the supported TEMPO catalyst containing a quaternary ammonium salt structure obtained in this example, the catalyst support before loading - the functionalized molecular sieve powder obtained in Step 1, and TEMPO was evaluated:
[0038] 3.25 g of benzyl alcohol was weighed and placed in a 250 mL three-necked flask. Then 30 g of acetonitrile and 0.77 g of the catalyst were added. The mixture was stirred and heated to 30 °C, and then 30 mL of sodium hypochlorite aqueous solution was added. Samples were taken at regular intervals and analyzed by liquid chromatography. The analysis conditions were a C18 chromatographic column, the mobile phase was 20% acetonitrile and 80% water, and the detection wavelength was 254 nm.
[0039] After reacting for 40 minutes, the content of benzyl alcohol in the supported TEMPO catalyst system containing quaternary ammonium salt structure obtained in this example is 0.79%, the content of benzoic acid is 0.02%, and the content of benzaldehyde is 99.19%.
[0040] After reacting for 40 minutes, the content of benzyl alcohol in the catalyst support - functionalized molecular sieve powder system before loading obtained in Step 1 is 58.37%, the content of benzoic acid is 0.02%, and the content of benzaldehyde is 41.61%.
[0041] After reacting for 40 minutes, the content of benzyl alcohol in the TEMPO system is 0.983%, the content of benzoic acid is 0.064%, and the content of benzaldehyde is 98.953%.
[0042] Example 2
[0043] This example provides a preparation method of a supported TEMPO catalyst, including the following steps:
[0044] Step 1: Prepare functionalized molecular sieve:
[0045] Add 5.0 g of molecular sieve with an average particle size of 20 nm, a specific surface area of 780 m 2 / g, and a pore diameter of 10 nm into a reaction flask, add 5.0 g of 3 - chloropropyltriethoxysilane and 100.0 g of toluene, reflux and react at 110 °C for 12 h, cool down, filter with suction to collect the filter residue, wash the filter residue successively with water, ethanol and dichloromethane, and dry at 80 °C for 8 h to obtain the functionalized molecular sieve;
[0046] Step 2: Add 4.17 g of amino - TEMPO into a 100 mL reaction flask, add 40 g of acetonitrile, add 3.35 g of anhydrous potassium carbonate and 16.68 g of benzyl bromide to the obtained system, heat to 80 °C under nitrogen protection, reflux and react for 10 h, wash the obtained reaction system successively with water, rotary - evaporate acetonitrile and extract with n - hexane to obtain the organic phase; the obtained organic phase is purified by column chromatography to obtain 5.45 g of red solid, which is 2,2,6,6 - tetramethyl - 4 - (dibenzylamino) - 1 - piperidinyloxy free radical;
[0047] Step 3: Add 7.02 g of the functionalized molecular sieve obtained in Step 1 into a 250 mL reaction flask, add 70 g of acetonitrile, add 5.45 g of 2,2,6,6 - tetramethyl - 4 - (dibenzylamino) - 1 - piperidinyloxy free radical obtained in Step 2, add 0.6 g of nucleophilic reaction catalyst DMAP (4 - dimethylaminopyridine), heat to 80 °C and stir and reflux for 16 h, cool down, filter with suction to collect the filter residue, wash successively with acetonitrile, water, acetonitrile and dichloromethane, and dry to obtain 8.17 g of supported TEMPO catalyst containing quaternary ammonium salt structure.
[0048] The structural formula of the quaternary ammonium salt in this example is:
[0049] R1 and R2 are benzyl groups, R3 is a n-propyl group, X is chlorine, and the TEMPO loading is 0.40 mmol / g.
[0050] Example 3
[0051] This example provides a method for preparing a supported TEMPO catalyst, which includes the following steps:
[0052] Step 1: Prepare functionalized molecular sieve:
[0053] Add 5.0 g of molecular sieve with an average particle size of 20 nm, a specific surface area of 780 m 2 / g, and a pore diameter of 10 nm into a reaction flask, add 5.0 g of 3-chloropropyltriethoxysilane and 100.0 g of toluene, reflux and react at 110 °C for 12 h, cool down, filter and collect the filter residue, wash the filter residue successively with water, ethanol and dichloromethane, and dry at 80 °C for 8 h to obtain the functionalized molecular sieve;
[0054] Step 2: Add 5.00 g of amino-TEMPO into a 100 mL reaction flask, add 50 g of acetonitrile, add 3.05 g of sodium tert-butoxide and 21.51 g of iodo-isobutane to the obtained system, heat to 80 °C under nitrogen protection, reflux and react for 10 h. The obtained reaction system is successively washed with water, rotary evaporated to remove acetonitrile, and extracted with n-hexane to obtain an organic phase; the obtained organic phase is purified by column chromatography to obtain 6.97 g of a red oily liquid, which is 2,2,6,6-tetramethyl-4-(diisobutylamino)-1-piperidinyloxy free radical;
[0055] Step 3: Add 7.00 g of the functionalized molecular sieve obtained in Step 1 into a 250 mL reaction flask, add 70 g of acetonitrile, add 3.0 g of 2,2,6,6-tetramethyl-4-(diisobutylamino)-1-piperidinyloxy free radical obtained in Step 2, add 0.6 g of the nucleophilic reaction catalyst DMAP (4-dimethylaminopyridine), heat to 80 °C and stir and reflux for 16 h, cool down, filter and collect the filter residue, wash it successively with acetonitrile, water, acetonitrile and dichloromethane, and dry to obtain 8.86 g of a supported TEMPO catalyst containing a quaternary ammonium salt structure.
[0056] The structural formula of the quaternary ammonium salt in this example is:
[0057] R1 and R2 are isobutyl groups, R3 is a n-propyl group, X is chlorine, and the TEMPO loading is 0.67 mmol / g.
[0058] Example 4
[0059] This embodiment provides a method for preparing a supported TEMPO catalyst, which includes the following steps:
[0060] Step 1: Prepare functionalized molecular sieve:
[0061] Add 5.0 g of molecular sieve with an average particle size of 20 nm, a specific surface area of 780 m 2 / g, and a pore size of 10 nm into a reaction flask, add 5.0 g of 3-chloropropyltriethoxysilane and 100.0 g of toluene, reflux at 110 °C for 12 h, cool down, filter with suction to collect the filter residue, wash the filter residue successively with water, ethanol and dichloromethane, and dry at 80 °C for 8 h to obtain the functionalized molecular sieve;
[0062] Step 2: Add 5.11 g of amino TEMPO into a 100 mL reaction flask, add 50 g of acetonitrile, add 1.68 g of potassium hydroxide and 27.12 g of n-heptyl iodide to the obtained system, heat to 80 °C under nitrogen protection, reflux for 10 h, wash the obtained reaction system successively with water, rotary evaporate acetonitrile and extract with n-hexane to obtain an organic phase; the obtained organic phase is purified by column chromatography to obtain 7.12 g of a red solid, which is 2,2,6,6-tetramethyl-4-(diheptylamino)-1-piperidinyloxy free radical;
[0063] Step 3: Add 7.03 g of the functionalized molecular sieve obtained in Step 1 into a 250 mL reaction flask, add 70 g of acetonitrile, add 4.2 g of 2,2,6,6-tetramethyl-4-(diheptylamino)-1-piperidinyloxy free radical obtained in Step 2, add 0.6 g of the nucleophilic reaction catalyst DMAP (4-dimethylaminopyridine), heat to 80 °C and stir and reflux for 16 h, cool down, filter with suction to collect the filter residue, wash successively with acetonitrile, water, acetonitrile and dichloromethane, and dry to obtain 7.89 g of a supported TEMPO catalyst containing a quaternary ammonium salt structure.
[0064] In this embodiment, the structural formula of the quaternary ammonium salt is:
[0065] R1 and R2 are n-heptyl, R3 is n-propyl, X is chlorine, and the TEMPO loading is 0.30 mmol / g.
Claims
1. A supported TEMPO catalyst, characterized in that, The quaternary ammonium salt with the following structural formula is used as the active component: R1 and R2 are alkyl or benzyl; R3 is n is 1 to 4; X is chlorine, bromine or iodine; with a functionalized molecular sieve as the carrier and the TEMPO loading is 0.2 to 0.8 mmol / g.
2. A preparation method of the supported TEMPO catalyst as described in claim 1, characterized in that, It includes the following steps: Step 1, prepare functionalized molecular sieve: reflux react a silane coupling agent and a molecular sieve in an organic solvent, cool down, filter by suction to collect the filter residue, wash the filter residue thoroughly and dry it to obtain the functionalized molecular sieve; Step 2, mix amino TEMPO, a first solvent, a base and a haloalkane or benzyl halide, heat and reflux under nitrogen protection, and wash the obtained reaction system successively with water, rotary evaporate the solvent and extract with n-hexane to obtain an organic phase; after purification of the obtained organic phase, 2,2,6,6-tetramethyl-4-(dialkylamino)-1-piperidinyloxy free radical or 2,2,6,6-tetramethyl-4-(dibenzylamino)-1-piperidinyloxy free radical is obtained; Step 3, mix the functionalized molecular sieve obtained in Step 1, a second solvent and the 2,2,6,6-tetramethyl-4-(dialkylamino)-1-piperidinyloxy free radical or 2,2,6,6-tetramethyl-4-(dibenzylamino)-1-piperidinyloxy free radical obtained in Step 2, add a nucleophilic reaction catalyst, heat and stir to reflux react, cool down, filter by suction to collect the filter residue, wash thoroughly and dry to obtain the supported TEMPO catalyst.
3. The preparation method of the supported TEMPO catalyst according to claim 2, wherein, The mass ratio of the silane coupling agent, the molecular sieve and the organic solvent in Step 1 is 1:1:20, and the silane coupling agent is a silane coupling agent with a halogen as the active functional group.
4. The preparation method of the supported TEMPO catalyst according to claim 2 or 3, characterized in that, The silane coupling agent described in Step 1 is 3-chloropropyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltriethoxysilane or 3-chloropropylmethyldiethoxysilane; the pore diameter of the molecular sieve is 2-60 nm, the particle size is 40-200 nm, and the specific surface area is 200-1700 m 2 / g; the organic solvent is toluene.
5. The preparation method of the supported TEMPO catalyst according to claim 4, characterized in that, The reflux reaction temperature in Step 1 is 70-110 °C and the time is 6-24 h; the washing is successively washing with water, ethanol and dichloromethane, and the drying is drying at 60-120 °C for 6-8 h.
6. The preparation method of the supported TEMPO catalyst according to claim 5, wherein, The mass ratio of the amino TEMPO and the first solvent in Step 2 is 1:2-20, the first solvent is acetonitrile or tetrahydrofuran, the molar ratio of the amino TEMPO and the base is 1:0.7-2, the base is anhydrous potassium carbonate, sodium hydroxide or sodium tert-butoxide, the molar ratio of the amino TEMPO and the haloalkane or benzyl halide is 1:3.5-5, the haloalkane or benzyl halide is a halo C1-C16 normal or isomeric alkane, and the benzyl halide is benzyl chloride, benzyl bromide or benzyl iodide.
7. The preparation method of the supported TEMPO catalyst according to claim 6, wherein The temperature of the heating reflux in Step 2 is 60-100 °C and the time is 6-24 h.
8. The preparation method of the supported TEMPO catalyst according to claim 7, characterized in that, The mass ratio of the functionalized molecular sieve and the second solvent in Step 3 is 1:20-50, the second solvent is acetonitrile, acetone, benzene or toluene; the mass ratio of the functionalized molecular sieve and the 2,2,6,6-tetramethyl-4-(dialkylamino)-1-piperidinyloxy free radical or 2,2,6,6-tetramethyl-4-(dibenzylamino)-1-piperidinyloxy free radical is 1:0.5-2; the mass ratio of the functionalized molecular sieve and the nucleophilic reaction catalyst is 1:0.01-0.2, and the nucleophilic reaction catalyst is DMAP.
9. The preparation method of the supported TEMPO catalyst according to claim 8, wherein The temperature of the heating and stirring reflux in Step 3 is 70-120 °C and the time is 10-20 h.
10. Use of the supported TEMPO catalyst as described in claim 1 in the catalytic selective oxidation of alcohols to aldehydes or ketones.