Titanium dioxide supported nickel catalyst, method of preparation and use

Abstract

The present application relates to a kind of titanium dioxide supported nickel catalyst, preparation method and application, and the catalyst includes metal-based active center and titanium dioxide carrier;Titanium dioxide supported nickel catalyst of the present application has higher tetrahydrocurcumin selectivity, when realizing curcumin 100% conversion rate, the selectivity of product tetrahydrocurcumin is all higher than 85%;Catalyst preparation process is simple, easy to operate, can realize the hydrogenation of high conversion rate and high selectivity of curcumin under low temperature, low pressure reaction condition, reduce the complexity of reaction system, suitable for industrial application.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a method for preparing and applying a supported catalyst for the hydrogenation of curcumin. Background Technology

[0002] Tetrahydrocurcumin is a hydrogenated derivative of curcumin isolated from the rhizome of the ginger plant (Curcuma longa). It is colorless and odorless. Due to its excellent antioxidant, antitumor, and anti-atherosclerotic effects and safety profile, it is used as a food additive in the food industry and as a novel pharmaceutical raw material and intermediate in the pharmaceutical industry. Currently, the main method for preparing tetrahydrocurcumin from curcumin is through chemical methods. Platinum group metals exhibit excellent performance in hydrogenation reactions and are therefore frequently used in the hydrogenation of curcumin.

[0003] Using precious metals in catalytic hydrogenation significantly increases production costs, while transition metal nickel, with its excellent activity and greater economic benefits, is often used to replace precious metals in hydrogenation reactions. Titanium dioxide, as a catalyst support, effectively prevents the sintering of active components, and its oxygen vacancy defects promote hydrogen adsorption, increasing catalytic activity. Liquid-phase reduction methods for catalyst preparation effectively control the shape of metal particles, and the steric hindrance effect of ethylene glycol and surfactants reduces particle size, thus increasing activity. Summary of the Invention

[0004] To address the shortcomings of the existing technology, this invention provides a method for preparing a supported catalyst for the hydrogenation of curcumin and its application. This method uses titanium dioxide as a support, disperses metal particles on the surface of the support, and controls the size and dispersion of metal particles in the supported catalyst by changing the reaction conditions and the amount of dispersant, thereby improving the catalytic performance of the supported catalyst, maintaining good catalytic activity and selectivity, and reducing the cost of the hydrogenation catalyst.

[0005] The technical solution adopted in this invention is as follows: To achieve the above objectives, a titanium dioxide-supported nickel catalyst, its preparation method, and its application are specifically as follows:

[0006] The nickel precursor, dispersant, and support were dispersed in a polyol solution and stirred overnight. Sodium hydroxide solution was then added to obtain a mixed slurry. This slurry was transferred to a hydrothermal reactor and subjected to liquid-phase reduction at 200°C for 3-6 hours to obtain a solid powder. This powder was washed with ethanol and water, dried, and then calcined at 400°C under a H2 atmosphere for 2 hours to obtain the supported nickel catalyst.

[0007] Preferably, the nickel precursor is nickel chloride hexahydrate, nickel nitrate hexahydrate, or nickel sulfate hexahydrate;

[0008] Preferably, the carrier is titanium dioxide;

[0009] Preferably, the polyol is ethylene glycol, 1,2-propanediol, or 1,4-butanediol;

[0010] Preferably, the dispersant is polyvinylpyrrolidone in a mass ratio of 3:4 to nickel precursor;

[0011] Preferably, the concentration of the sodium hydroxide solution is 0.8 mol / L;

[0012] Preferably, the mass ratio of the nickel precursor to the carrier is 0.6:1.

[0013] In this invention, the raw materials used are nickel chloride hexahydrate, nickel nitrate hexahydrate, and nickel sulfate hexahydrate, and the dispersant is polyvinylpyrrolidone. The optimal reduction time is 4 hours. When this supported nickel catalyst is used in the hydrogenation reaction of curcumin, the selectivity for tetrahydrocurcumin reaches 90% at a curcumin conversion rate of 100%, achieving industrial application level.

[0014] Compared with the prior art, the advantages of the present invention are: the nickel precursor and support are dispersed in ethylene glycol solution by liquid phase reduction, and the supported nickel catalyst is prepared by reduction under alkaline conditions. This can effectively control the morphology, size and dispersion of metal particles, and is low in cost, with good prospects for industrial application. Attached Figure Description

[0015] Figure 1 The image shows the XRD pattern of the titanium dioxide support prepared by hydrothermal method in Example 1 of this invention.

[0016] Figure 2 The image shows the XRD pattern of the Ni / TiO2 catalyst prepared in Example 1 of this invention.

[0017] Figure 3 The isothermal adsorption-desorption curves of the titanium dioxide support prepared by hydrothermal method in Example 1 of this invention are shown. Detailed Implementation

[0018] This invention discloses a titanium dioxide-supported nickel catalyst, its preparation method, and its application. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve the desired results. In particular, it should be noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art can obviously modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0019] Example 1: Preparation of Ni / TiO2 catalyst

[0020] Take 0.6g of nickel chloride hexahydrate and 0.45g of polyvinylpyrrolidone and dissolve them in 5mL of ethylene glycol. Add 1g of titanium dioxide support and stir overnight. Then add 25mL of ethylene glycol solution of 0.8mol / L sodium hydroxide and stir for 1 hour. Transfer the resulting slurry to a hydrothermal reactor and reduce it at 200℃ for 4 hours. The reaction solution is then filtered, washed with ethanol and deionized water, dried, and calcined at 400℃ for 2 hours in H2 atmosphere to obtain the Ni / TiO2 catalyst.

[0021] Example 2: Preparation of Ni / TiO2 catalyst

[0022] 0.74 g of nickel nitrate hexahydrate and 0.45 g of polyvinylpyrrolidone were dissolved in 5 mL of ethylene glycol. 1 g of titanium dioxide support was added and stirred overnight. Then, 25 mL of ethylene glycol solution of 0.8 mol / L sodium hydroxide was added and stirred for 1 hour. The resulting slurry was transferred to a hydrothermal reactor and reduced at 200 °C for 4 hours. The reaction solution was then filtered, washed with ethanol and deionized water, dried, and calcined at 400 °C for 2 hours in an H2 atmosphere to obtain the Ni / TiO2 catalyst.

[0023] Example 3: Preparation of Ni / TiO2 catalyst

[0024] Take 0.74g of nickel sulfate hexahydrate and 0.45g of polyvinylpyrrolidone and dissolve them in 5mL of ethylene glycol. Add 1g of titanium dioxide support and stir overnight. Then add 25mL of ethylene glycol solution of 0.8mol / L sodium hydroxide and stir for 1 hour. Transfer the resulting slurry to a hydrothermal reactor and reduce it at 200℃ for 4 hours. The reaction solution is then filtered, washed with ethanol and deionized water, dried, and calcined at 400℃ for 2 hours in H2 atmosphere to obtain the Ni / TiO2 catalyst.

[0025] Example 4: Preparation of Ni / TiO2 catalyst

[0026] Take 0.6g of nickel chloride hexahydrate and 0.45g of polyvinylpyrrolidone and dissolve them in 5mL of 1,2-propanediol. Add 1g of titanium dioxide support and stir overnight. Then add 25mL of 0.8mol / L sodium hydroxide solution in 1,2-propanediol and stir for 1 hour. Transfer the resulting slurry to a hydrothermal reactor and reduce it at 200℃ for 4 hours. The reaction solution is then filtered, washed with ethanol and deionized water, dried, and calcined at 400℃ for 2 hours in H2 atmosphere to obtain the Ni / TiO2 catalyst.

[0027] Example 5: Preparation of Ni / TiO2 catalyst

[0028] Take 0.67g of nickel sulfate hexahydrate and 0.45g of polyvinylpyrrolidone and dissolve them in 5mL of 1,2-propanediol. Add 1g of titanium dioxide support and stir overnight. Then add 25mL of 0.8mol / L sodium hydroxide solution in 1,2-propanediol and stir for 1 hour. Transfer the resulting slurry to a hydrothermal reactor and reduce it at 200℃ for 4 hours. The reaction solution is then filtered, washed with ethanol and deionized water, dried, and calcined at 400℃ for 2 hours in H2 atmosphere to obtain the Ni / TiO2 catalyst.

[0029] Example 6: Preparation of Ni / TiO2 catalyst

[0030] 0.74 g of nickel nitrate hexahydrate and 0.45 g of polyvinylpyrrolidone were dissolved in 5 mL of ethylene glycol. 1 g of titanium dioxide support was added and stirred overnight. Then, 25 mL of ethylene glycol solution of 0.8 mol / L sodium hydroxide was added and stirred for 1 hour. The resulting slurry was transferred to a hydrothermal reactor and reduced at 200 °C for 4 hours. The reaction solution was then filtered, washed with ethanol and deionized water, dried, and calcined at 400 °C for 2 hours in an H2 atmosphere to obtain the Ni / TiO2 catalyst.

[0031] Example 7 Preparation of Ni / TiO2 catalyst

[0032] 0.74 g of nickel nitrate hexahydrate and 0.45 g of polyvinylpyrrolidone were dissolved in 5 mL of 1,4-butanediol. 1 g of titanium dioxide support was added and stirred overnight. Then, 25 mL of 1,4-butanediol solution of 0.8 mol / L sodium hydroxide was added and stirred for 1 hour. The resulting slurry was transferred to a hydrothermal reactor and reduced at 200 °C for 4 hours. The reaction solution was then filtered, washed with ethanol and deionized water, dried, and calcined at 400 °C for 2 hours in an H2 atmosphere to obtain the Ni / TiO2 catalyst.

[0033] Table 1 Effect of different catalysts on the catalytic hydrogenation of curcumin

[0034]

[0035] As shown in Table 1, the supported Ni / TiO2 catalyst prepared by the liquid-phase reduction method requires relatively mild preparation conditions. When used for the selective hydrogenation of curcumin to tetrahydrocurcumin, the above catalyst exhibits excellent reactivity, achieving a tetrahydrocurcumin selectivity of 85% when the curcumin conversion rate is 100%. The catalyst prepared in this invention can meet the needs of industrial production.

[0036] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these should also be considered within the scope of protection of the present invention.

Claims

1. An application of a titanium dioxide-supported nickel catalyst, characterized in that, Curcumin was dissolved in acetone solution, and H2 was introduced at room temperature at a pressure of 0.4 MPa to carry out a catalytic hydrogenation reaction to obtain tetrahydrocurcumin. The catalyst was prepared by dispersing a nickel precursor, a dispersant, and a support in a polyol solution, stirring overnight, and then adding sodium hydroxide solution to obtain a mixed slurry. The slurry was transferred to a hydrothermal reactor and reduced in the liquid phase at 200°C for 3-6 hours to obtain a solid powder. After washing with ethanol and water and drying, the powder was calcined at 400°C under an H2 atmosphere for 2 hours to obtain a supported nickel catalyst. The nickel precursor was nickel chloride hexahydrate, nickel nitrate hexahydrate, or nickel sulfate hexahydrate. The support was titanium dioxide. The polyol was ethylene glycol, 1,2-propanediol, or 1,4-butanediol. The dispersant was polyvinylpyrrolidone.

2. The application according to claim 1, characterized in that, The dispersant polyvinylpyrrolidone has a mass ratio of 3:4 to the nickel precursor.

3. The application according to claim 1, characterized in that, The concentration of the sodium hydroxide solution is 0.8 mol / L.

4. The application according to claim 1, characterized in that, The mass ratio of the nickel precursor to the carrier is 0.6:

1.

5. The application according to claim 1, characterized in that, The reaction temperature for the catalytic hydrogenation reaction is 30°C.

Images