Method for preparing hydrotalcite supported silver catalyst and application thereof

A silver catalyst, hydrotalcite technology, applied in chemical instruments and methods, oxidative preparation of carbonyl compounds, catalysts for physical/chemical processes, etc., can solve the problem that the conversion rate or selectivity is not particularly satisfactory, and the catalyst is expensive to synthesize cost. The synthesis process is widely used, a large number of by-products, etc., to achieve the effect of convenient industrial production, high yield, and high conversion rate of reactants

Inactive Publication Date: 2011-08-03
BEIJING UNIV OF CHEM TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The traditional preparation methods of styrene oxide include haloalcohol method or peracid method. These traditional methods not only have many steps, but also produce a large number of by-products, causing serious environmental pollution. The preparation of fine chemicals by clean catalytic process is the future of fine chemicals Main route of production. Directly from H 2 o 2 Epoxidation of styrene as oxidant is a better way to achieve green catalysis
With hydrogen peroxide as the ox

Method used

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  • Method for preparing hydrotalcite supported silver catalyst and application thereof
  • Method for preparing hydrotalcite supported silver catalyst and application thereof

Examples

Experimental program
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Example Embodiment

[0020] Example 1

[0021] A: Weigh 61.54g Mg(NO 3 ) 2 ·6H 2 O and 45.02g Al(NO 3 ) 3 ·9H 2 O is dissolved in deionized water to make 300mL mixed salt solution; then weigh 23.04g NaOH and 25.44g Na 2 CO 3 Dissolve in deionized water to prepare 300mL mixed alkali solution; add the above two mixed solutions into the fully backmixed liquid membrane reactor at the same time, adjust the width of the slit between the reactor rotor and the stator to 0.02mm, the working voltage is 100V, and the rotor speed At 4000 rpm, the obtained mixed slurry was added to the crystallization kettle and stirred, and the temperature of the mixed slurry in the kettle was maintained at 95-105°C for reflux crystallization for 6 hours to obtain a magnesium-aluminum hydrotalcite precursor slurry; a magnesium-aluminum hydrotalcite precursor After centrifugal washing the pH to 7.5, and drying at 90°C for 24 hours, the magnesium-aluminum hydrotalcite is obtained. Its chemical formula is [Mg 2 Al(OH) 6 ] + (CO 3 2-...

Example Embodiment

[0025] Example 2

[0026] A: Same as Example 1;

[0027] B: Under the condition of 0℃, measure 10ml of 7.88g / L silver nitrate solution, add 1.0g of magnesium-aluminum hydrotalcite, and then add 10ml of deionized water, add the above substances into a 50ml flat-bottomed flask respectively, and magnetically stir at 0℃. Keep at a constant temperature for 60 minutes; add 10ml of ascorbic acid solution with a concentration of 17.5g / L and a temperature of 0°C to the above solution, keep it at 0°C for 1 hour, and centrifuge the slurry for 3 times until there is no chloride ion, and dry at 70°C , Take it out after 10h, put it in a vacuum desiccator for storage.

[0028] The above-prepared hydrotalcite-supported silver catalyst is used to catalyze the oxidation of styrene to phenylethylene oxide. The reaction conditions are as follows: reaction temperature is 82°C, reaction pressure is normal pressure, acetonitrile is used as solvent, and the amount of solvent is 5ml / 10mmol Add 0.086 g of t...

Example Embodiment

[0030] Example 3

[0031] A: Same as Example 1;

[0032] B: Under the condition of 0℃, measure 2ml of 7.88g / L silver nitrate solution, add 1.0g of magnesium-aluminum hydrotalcite, and 10ml of deionized water. Add the above substances into a 50ml flat-bottomed flask, and stir magnetically at 0℃. Keep at a constant temperature for 50 minutes; add 10ml of sodium citrate solution with a concentration of 17.5g / L and a temperature of 0°C to the above solution, keep it at 0°C for 1 hour, and centrifuge the slurry for 3 times after the reaction until there is no chloride ion, 70 Dry at ℃, take it out after 10h and put it in a vacuum desiccator for storage.

[0033] The above-prepared hydrotalcite-supported silver catalyst is used to catalyze the oxidation of styrene to phenylethylene oxide. The reaction conditions are as follows: reaction temperature is 82°C, reaction pressure is normal pressure, acetonitrile is used as solvent, and the amount of solvent is 5ml / 10mmol styrene, Add 0.086 g ...

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Abstract

The invention discloses a method for preparing a supported silver catalyst with low load and high activity by using hydrotalcite as a carrier in the technical field of catalyst preparation. The hydrotalcite is used as the carrier, and silver atoms with catalytic activity are highly dispersed and tightly anchored on the high-energy crystal face of the hydrotalcite by using uniform hydroxyl dot matrix and different crystal face orientation of the hydrotalcite so that more active silver particles are exposed. The invention provides the method for preparing the supported silver catalyst, and the method has the advantages of simple equipment and process, high yield, convenience in industrialized production, low prepared silver granularity and good reproducibility. When the catalyst is applied in synthesis of styrene oxide by catalytic oxidation of styrene, the conversion rate of reactants is high, and the selectivity of a product is high.

Description

technical field [0001] The invention belongs to the technical field of catalyst preparation, and in particular relates to a highly active loaded silver catalyst with hydrotalcite as a carrier and a preparation method thereof. Background technique [0002] Hydrotalcites (LDHs), also known as double hydroxyl complex metal hydroxides, are anionic clays with a general chemical formula [M II 1-x m III x (OH) 2 ] x+ (A n- ) x / n ·yH 2 O, where M II and M III They are divalent and trivalent metal cations respectively, located on the main laminate; A n- is an interlayer anion; x is M III / (M II +M III ) molar ratio; y is the number of interlayer water molecules. LDHs have a layered structure, tunability of layer elements and exchangeability of anions between layers. This special chemical and structural property not only makes it have ion exchange properties, but also has a wide range of applications in many fields such as catalysis, adsorption, ion exchange, electrical...

Claims

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Application Information

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IPC IPC(8): B01J23/66C07D303/04C07D301/12C07C47/54C07C47/228C07C45/28
Inventor 徐赛龙王晓彤梁忠强卫敏张法智
Owner BEIJING UNIV OF CHEM TECH
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