CN104971784A - Preparation method of supported metal catalysts - Google Patents

Abstract

The invention discloses a method for preparing a supported metal catalyst, relating to the metal catalyst. A method for preparing a supported metal catalyst with long-term stability under high temperature conditions is provided while retaining the advantages of simplicity and low cost of the conventional impregnation method. The metal salt, silicon dioxide, additives and water are mixed to form a mixture, and the mixture is sequentially impregnated, dried, calcined and reduced to obtain a supported metal catalyst. A series of metal-based supported catalysts were prepared by an improved impregnation method, which have the characteristics of high metal dispersion, high catalytic activity, high stability, anti-sintering, etc., and have good industrial application prospects. The method has the advantages of simple process, stability, good repeatability, low cost and the like.

Description

Preparation method of supported metal catalyst

technical field

The invention relates to a metal catalyst, in particular to a preparation method of a highly stable supported metal catalyst.

Background technique

The supported metal catalyst prepared by impregnation method is suitable for mass production due to its simple operation and low cost. At the same time, supported metal catalysts have good catalytic activity for reactions such as Fischer-Tropsch synthesis and partial oxidation of methane to synthesis gas, and have large-scale industrial application prospects and economic needs. In the supported metal catalysts prepared by impregnation method, the interaction between the active metal particles and the support is weak, and the catalysts generally have the disadvantages of uneven dispersion of metal particles and easy sintering at high temperature leading to deactivation. The instability under high-temperature reaction conditions seriously hinders its industrial application. In order to improve the high-temperature instability of supported metal catalysts prepared by impregnation, a series of new catalyst preparation methods have been developed successively.

Chinese patent 201410183765.3 uses titanium precursor and ethanol, acetic acid, water to form titanium sol, then adds nickel precursor and Al ₂ O ₃ carrier, and then obtains Ni/TiO ₂ -Al ₂ O ₃ supported catalyst by impregnation method, which has good Pinene hydrogenation conversion and selectivity.

Chinese patent 201310148930.7 uses red phosphorus, nickel chloride and a carrier to mix uniformly in an aqueous solution under strong alkali conditions, and then prepares a nickel phosphide supported catalyst by successively hydrothermal, filtering and vacuum drying methods.

U.S. Patent US 20140349836A1 uses Al ₂ O ₃ gel prepared by a special method as a carrier, and a Ni/Al ₂ O ₃ supported catalyst is prepared by a conventional impregnation method, which has good persistence of reactivity under high temperature and high pressure.

However, the above methods either make the catalyst preparation process more complicated, or increase the preparation cost of the catalyst. Therefore, how to prepare supported metal catalysts with long-term stability under high temperature conditions while retaining the advantages of simplicity and low cost of the conventional impregnation method is of great economic significance.

Contents of the invention

The object of the present invention is to solve the problem that supported metal catalysts are easily deactivated under high temperature conditions, and provide a supported metal catalyst with long-term stability under high temperature conditions while retaining the convenience and low cost advantages of conventional impregnation methods method of preparation.

Concrete steps of the present invention are as follows:

The metal salt, silicon dioxide, additives and water are mixed to form a mixture, and the mixture is sequentially impregnated, dried, calcined and reduced to obtain a supported metal catalyst.

The metal salt can be selected from one of iron salts, cobalt salts, nickel salts, copper salts, zinc salts, silver salts and the like.

The additive can be selected from arginine, ammonia water, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine and the like.

According to mass percentage, the content of metal salt, silicon dioxide, additive and water can be: 0.1%-20% of metal salt, 10%-60% of silicon dioxide, 0.01%-10% of additive, and the balance is water.

The drying temperature may be 80-200°C, the roasting temperature may be 300-1000°C, and the reduction temperature may be 500-1000°C.

The existing supported metal catalysts prepared by the impregnation method generally have the characteristics of high temperature instability. Compared with this, the present invention has the following outstanding advantages:

(1) On the basis of the conventional impregnation method, the present invention prepares a supported metal catalyst with long-term stability under high temperature conditions only by adding a small amount of additives.

(2) The present invention is a preparation method of a universal highly stable supported metal catalyst.

(3) The metal nano-particles in the supported metal catalyst prepared by the present invention have a small and uniform particle size and are highly dispersed, which guarantees the catalytic activity of industrial reactions.

(4) While retaining the advantages of simplicity and low cost of the conventional impregnation method, a supported metal catalyst with long-term stability at high temperature has been prepared, which is suitable for industrial applications and has great economic significance.

(5) It is suitable for the preparation of supported metal catalysts of various materials to meet various industrial reaction applications.

(6) Less equipment, simple process and less difficult operation.

(7) There are few sources of raw material pollution, and the process is environmentally friendly.

(8) The price is cheap, the cost is low, and it can be mass-produced.

Description of drawings

Fig. 1 is the transmission electron microscope image of Ni/SiO ₂ after reduction in Example 6. It can be seen from the figure that the Ni nanoparticles are small and uniform in size, highly dispersed without agglomeration.

Fig. 2 is the time-varying diagram of the high-temperature reaction performance of Example 9. It can be seen from the figure that there is almost no change in the catalytic performance after the reaction lasts for 500 hours, indicating that the catalyst has good high temperature stability and is suitable for industrial applications.

Detailed ways

Below by example in conjunction with accompanying drawing the present invention will be further described.

Example 1

Weigh cobalt nitrate, silicon dioxide, and arginine with mass percentages of 0.1%, 10%, and 0.01%, respectively, and add them to 1 ton of water, and stir to mix evenly. Dry at 150°C, calcined at 600°C, and reduce with _H2 at 600°C to obtain a Co/ _SiO2 supported catalyst.

Example 2

The mass percentages in Example 1 were replaced by 10%, 20%, and 8% in turn, and arginine was replaced by methylamine to obtain a Co/SiO ₂ supported catalyst.

Example 3

The mass percentage in Example 1 was replaced by 20%, 60%, and 10% in turn to obtain a Co/SiO ₂ supported catalyst.

Example 4

Arginine in Example 1 was replaced by ethylamine, dried at 80°C, calcined at 300°C, and reduced at 500°C to obtain a Co/SiO ₂ supported catalyst.

Example 5

In Example 1, cobalt nitrate was replaced by iron nitrate, arginine was replaced by n-propylamine, dried at 200°C, calcined at 1000°C, and reduced at 1000°C to obtain Fe/SiO ₂ supported catalyst.

Example 6

In Example 1, cobalt nitrate was replaced by nickel nitrate, and arginine was replaced by ammonia water to obtain Ni/ _SiO2 supported catalyst, as shown in Figure 1.

Example 7

Cobalt nitrate in Example 1 was replaced by copper nitrate to obtain Cu/SiO ₂ supported catalyst.

Example 8

Cobalt nitrate in Example 6 was replaced by silver nitrate to obtain Ag/SiO ₂ supported catalyst.

Example 9

The Ni/SiO ₂ supported catalyst prepared in Example 6 was used for the reaction of partial oxidation of methane to synthesis gas. The reaction conditions were: 750°C, CH ₄ /O ₂ =2/1, GHSV=100000mL·g-cat ^-1 · h ^-1 . The response performance as a function of time is shown in Fig. 2.

The invention uses an improved impregnation method to prepare a series of metal-based supported catalysts, which have the characteristics of high metal dispersion, high catalytic activity, high stability, anti-sintering and the like, and have good industrial application prospects. The preparation method has the advantages of simple process, stability, good repeatability, low cost and the like.

Claims (7)

1. the preparation method of supported metal catalyst is characterized in that its concrete steps are as follows: The metal salt, silicon dioxide, additives and water are mixed to form a mixture, and the mixture is sequentially impregnated, dried, calcined and reduced to obtain a supported metal catalyst. 2. the preparation method of supported metal catalyst as claimed in claim 1, is characterized in that described metal salt is selected from the one in iron salt, cobalt salt, nickel salt, copper salt, zinc salt, silver salt. 3. the preparation method of supported metal catalyst as claimed in claim 1 is characterized in that said additive is selected from arginine, ammoniacal liquor, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine kind of. 4. the preparation method of supported metal catalyst as claimed in claim 1 is characterized in that by mass percentage, the content of metal salt, silicon dioxide, additive and water is: metal salt 0.1%～20%, silicon dioxide 10% ～60%, additive 0.01%～10%, the balance is water. 5. The preparation method of the supported metal catalyst according to claim 1, characterized in that the drying temperature is 80-200°C. 6. The preparation method of the supported metal catalyst according to claim 1, characterized in that the temperature of the calcination is 300-1000°C. 7. The preparation method of the supported metal catalyst according to claim 1, characterized in that the reduction temperature is 500-1000°C.