CN103349988A - Platinoid bi-component catalyst as well as preparation method and application thereof - Google Patents

Abstract

The invention discloses a platinum-copper two-component catalyst and its preparation method and application. The catalyst uses γ-Al ₂ O ₃ as a carrier, platinum metal as an active component, and copper metal as an auxiliary agent; The γ-Al ₂ O ₃ powder is first impregnated in Cu(NO ₃ ) ₂ aqueous solution, the solvent is removed, dried, and calcined, and then the obtained copper-loaded catalyst is impregnated in H ₂ PtCl ₆ aqueous solution, the solvent is removed, dried, and calcined ; The platinum-copper dual-component catalyst can be used for propane dehydrogenation to propylene. The copper metal and platinum metal of the catalyst of the present invention can interact with each other to change the interaction force between the reactant and the product and the metal surface, so as to ensure better performance under high temperature conditions when used for propane dehydrogenation to propylene Reaction stability, high propane conversion rate, and good propylene selectivity; in addition, different components of the catalyst are impregnated by the step-by-step impregnation method, and the component content is easy to control and the repeatability is good.

Description

A kind of platinum-copper two-component catalyst and its preparation method and application

technical field

The invention relates to a catalyst and its preparation method and application, in particular to a catalyst for propane dehydrogenation to propylene, its preparation method and application.

Background technique

Propylene is one of the most important petrochemical products and is widely used as the main raw material for the production of chemicals such as acrylonitrile, propylene oxide and acrylic acid. In recent years, driven by the rapid development of industries such as real estate, automobiles, packaging, and textiles and clothing, there has been a huge volume and gap in the propylene market, which makes propylene the most promising large petrochemical product at present. The existing propylene mainly comes from by-products or co-productions such as traditional processes such as petroleum catalytic cracking and naphtha reforming. The traditional process is affected by factors such as oil supply and product distribution, and the supply of propylene cannot meet the existing market demand. Therefore, propane dehydrogenation technology has attracted extensive attention from researchers.

The propane dehydrogenation process can convert cheap propane raw materials into high-value olefin products through a gas-solid catalytic process. The product system is simple and the yield of propylene is high. my country's abundant natural gas resources can provide abundant and cheap propane raw materials for the propane dehydrogenation process. In addition, the propane dehydrogenation process has 20 years of industrial production experience, and there are more than 20 sets of process production equipment in the world, and the process technology is mature. Considering factors such as economy and process maturity, the propane dehydrogenation process has attracted much attention. The industrialized propane dehydrogenation processes in the world mainly include Oleflex process of UOP Company, Catofin process of Lummus Company, Star process of Phillips Company, Linde process and FBD fluidized bed process. Among them, UOP's Oleflex process occupies more than three-quarters of the market share, and is currently the most widely used process technology for propane dehydrogenation to produce propylene. The Pt/Al ₂ O ₃ catalyst is used in the Oleflex process of UOP Company. The Pt/Al ₂ O ₃ catalyst has high catalytic activity and propylene selectivity, and is environmentally friendly. However, the Pt/Al2O3 catalyst also has disadvantages: it is easy to deactivate due to carbon deposition during the reaction, thereby reducing the yield of propylene.

In the research, the carbon deposition is generally reduced, the deactivation is suppressed, and the propylene yield is increased by adding additives or designing and changing the carrier properties. Yu Changlin et al[Effect of Ce addition on the Pt-Sn/γ-Al2O3catalyst for propanedehydrogenation to propylene.Applied Catalysis A:General.2006,315,58-67.] studied the effect of tin and cerium additives on platinum/alumina catalyst . At the beginning of the reaction, the conversion of propane over the Pt/Al catalyst was 34.10%, and the selectivity of propylene was 64.10%. After 150 minutes of reaction, the conversion of propane over the Pt/Al catalyst was 18.65%, and the selectivity of propylene was 88.18%. After adding tin and cerium promoters, the initial propane conversion of Pt-Sn/1.1Ce-Al catalyst was 43.78%, and the initial propylene selectivity was 92.54%. After 150 minutes of reaction, the conversion of propane over the Pt-Sn/1.1Ce-Al catalyst was 39.76%, and the selectivity of propylene was 97.19%. From the above, it can be concluded that the addition of the promoter improves the conversion rate and propylene selectivity of the catalyst, thereby increasing the propylene yield of the catalyst. However, the activity of the catalyst decreases rapidly, and the stability of the catalyst still needs to be improved. M.Santhosh Kumar et al[Dehydrogenation of propane over Pt-SBA-15and Pt-Sn-SBA-15:Effect of Sn on the dispersion of Pt and catalytic behavior] studied a platinum catalyst based on SBA-15 and tin The role of additives in the system. The Pt-SBA-15 catalyst had an initial propane conversion of 13% and an initial propylene selectivity of 85%. After 220 minutes of reaction, the conversion of propane over the Pt-SBA-15 catalyst was 12%, and the selectivity of propylene was 78%. The Pt-Sn-SBA-15 catalyst had an initial propane conversion of 16% and an initial propylene selectivity of 99% after adding tin promoter. After 220 minutes of reaction, the conversion of propane over the Pt-Sn-SBA-15 catalyst was 16%, and the selectivity of propylene was 99%. It can be known that the addition of tin additives improves the conversion rate and propylene selectivity of the catalyst. Auxiliaries help to improve the reactivity of the catalyst, which ultimately increases the conversion of propylene. This is mainly because compared with the alumina catalyst, the SBA-15 catalyst reduces the amount of acid active sites on the support, thereby improving the stability of the catalyst. However, the propane conversion rate of the catalyst is low and needs to be further improved.

Contents of the invention

The present invention aims to solve the technical problems that platinum-based catalysts currently used for propane dehydrogenation to propylene are easily deactivated and the yield of propylene is low, and provide a platinum-copper dual-component catalyst and its preparation method and application. Good reaction stability, high propane conversion rate and propylene selectivity, so that higher propylene yield can be obtained.

In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

A platinum-copper two-component catalyst, the catalyst uses γ-Al ₂ O ₃ as a carrier, platinum metal as an active component, and copper metal as an auxiliary agent; based on the total mass of the catalyst, the mass percentage of platinum metal is 0.3-1.0%, the mass percentage of copper metal is 0.25-2.0%; and, the catalyst is prepared by the following method:

(1) Immerse the carrier γ-Al ₂ O ₃ powder in 9.84*10 ^-4 M-3.15*10 ^-2 M Cu(NO ₃ ) ₂ aqueous solution at 40-80°C for 4-8 hours, in which The ratio of the mass of the carrier to the volume of the Cu(NO ₃ ) ₂ aqueous solution is 1g:(10-40)ml;

(2) Remove the solvent, dry at 100-140°C for 8-12h, and roast at 400-600°C for 2-6h to obtain a copper-supported catalyst;

(3) Immerse the obtained copper-supported catalyst in 3.84*10 ^-4 M-5.13*10 ^-3 M H ₂ PtCl ₆ aqueous solution at 40-80°C for 4-8 hours, wherein the mass of the support is the same as that of the The volume ratio of H ₂ PtCl ₆ aqueous solution is 1g:(10-40)ml;

(4) Remove the solvent, dry at 100-140°C for 8-12 hours, and roast at 400-600°C for 2-6 hours to obtain a platinum-copper dual-component catalyst.

A preparation method of platinum-copper two-component catalyst, the method is carried out according to the following steps:

(1) Immerse the carrier γ-Al ₂ O ₃ powder in 9.84*10 ^-4 M-3.15*10 ^-2 M Cu(NO ₃ ) ₂ aqueous solution at 40-80°C for 4-8 hours, in which The ratio of the mass of the carrier to the volume of the Cu(NO ₃ ) ₂ aqueous solution is 1g:(10-40)ml;

(2) Remove the solvent, dry at 100-140°C for 8-12h, and roast at 400-600°C for 2-6h to obtain a copper-supported catalyst;

(3) Immerse the obtained copper-supported catalyst in 3.84*10 ^-4 M-5.13*10 ^-3 M H ₂ PtCl ₆ aqueous solution at 40-80°C for 4-8 hours, wherein the mass of the support is the same as that of the The volume ratio of H ₂ PtCl ₆ aqueous solution is 1g:(10-40)ml;

(4) Remove the solvent, dry at 100-140°C for 8-12 hours, and roast at 400-600°C for 2-6 hours to obtain a platinum-copper dual-component catalyst.

A method in which the platinum-copper two-component catalyst is used for propane dehydrogenation to produce propylene, the method is carried out according to the following steps:

(1) Press the powdery platinum-copper two-component catalyst into 20-40 mesh granular platinum-copper two-component catalyst;

(2) Put the platinum-copper two-component catalyst after tableting into a fixed-bed reactor, pass in hydrogen-nitrogen mixed gas, and pre-reduce the platinum-copper two-component catalyst at 500-600°C by 1- 3h; the volume content of hydrogen in the hydrogen-nitrogen mixture is 10%;

(3) After the reduction is completed, control the temperature of the fixed-bed reactor to 500-700°C, and feed the reaction gas into the fixed-bed reactor at a propane mass space velocity of 3-10h ^-1 for reaction. The reaction gas is composed of propane, hydrogen and nitrogen. , where the flow ratio of propane and hydrogen is 1:1, and nitrogen is the balance gas.

The beneficial effects of the present invention are:

(1) The catalyst of the present invention uses γ-Al ₂ O ₃ as a carrier, which has a relatively high specific surface area and mesoporous channels, which is beneficial to the uniform distribution of active components and additives; platinum metal is used as an active component, and copper metal is used As an auxiliary agent, the interaction between copper metal and platinum metal can change the interaction force between the reactant and product and the metal surface, thereby improving the selectivity of propylene and the stability of the reaction while ensuring a high conversion rate of propane ;

(2) The catalyst preparation method of the present invention adopts a step-by-step impregnation method to impregnate different components of the catalyst, and its component content is easy to control and has good repeatability;

(3) The catalyst of the present invention is used for propane dehydrogenation to produce propylene, and has good reaction stability at high temperature (>500°C), high propane conversion rate and good propylene selectivity.

Detailed ways

The present invention will be described in further detail below through specific examples. The following examples can enable those skilled in the art to understand the present invention more comprehensively, but do not limit the present invention in any way.

Example 1:

(1) Immerse the carrier γ-Al ₂ O ₃ powder in 2.62*10 ^-3 M Cu(NO ₃ ) ₂ aqueous solution at 60°C for 6 hours, the ratio of carrier mass to solution volume is 1g:30ml;

(2) The eggplant-shaped bottle is connected to a rotary evaporator, and the rotary evaporator is connected to a vacuum pump. The solvent water is removed by a rotary evaporator under reduced pressure, dried at 120°C for 12 hours, and roasted at 550°C for 4 hours to obtain a copper-supported catalyst powder;

(3) Immerse the prepared copper-supported catalyst powder in 8.54*10 ^-4 M H ₂ PtCl ₆ aqueous solution at 60°C for 6 hours, and the ratio of carrier mass to solution volume is 1g:30ml;

(4) The eggplant-shaped bottle is connected to a rotary evaporator, and the rotary evaporator is connected to a vacuum pump. The solvent water is removed by a rotary evaporator under reduced pressure, dried at 120°C for 12 hours, and roasted at 550°C for 4 hours to obtain platinum copper. Two-component catalyst powder.

Based on the total mass of the platinum-copper dual-component catalyst, the composition is: Pt0.5%, Cu0.5%.

(5) Tablet the prepared platinum-copper two-component catalyst powder into platinum-copper two-component catalyst particles with a particle size within the range of 20-40 mesh;

(6) Put the prepared platinum-copper two-component catalyst particles into a fixed-bed reactor, use a hydrogen-nitrogen mixture with a hydrogen volume content of 10%, and use a flow rate of 50ml/min to treat the platinum-copper catalyst at a temperature of 550°C. Two-component catalyst pre-reduction for 2 hours;

(7) After the reduction is completed, raise the temperature of the fixed-bed reactor to 600°C, and feed the reaction gas into the fixed-bed reactor. The reaction gas is composed of propane, hydrogen and nitrogen, and the mass space velocity of propane is 3h ^-1 , The flow ratio of propane and hydrogen is 1:1, and _N2 is the balance gas.

The reaction tail gas was analyzed online by gas chromatography, and the relationship between propane conversion rate and propylene selectivity and time is shown in Table 1.

Table 1 Propane conversion and propylene selectivity and propylene yield at different reaction times

It can be seen that the catalyst has high propane conversion rate and high propylene selectivity, and the catalyst also shows good reaction stability. With the change of reaction time, the conversion rate of propane decreased gradually, and the selectivity of propylene gradually increased, which was mainly caused by the deactivation of the catalyst, and the reduction of the active site led to the weakening of the bond breaking ability, so that the selectivity of propylene has increased. When the reaction lasted for 4 hours, the catalyst still showed a relatively high propane conversion rate (42.8%) and propylene selectivity (90.4%), thereby having a relatively good propylene yield (38.7%), reflecting the platinum-copper dual-component The catalyst has better reaction stability.

Example 2:

The method in Example 1 was used for the reaction, the only difference being that the immersion temperatures of step (1) and step (3) were both 40°C.

Example 3:

The method of Example 1 was used for the reaction, the only difference being that the immersion temperatures of step (1) and step (3) were both 80°C.

Example 4:

The method in Example 1 was used for the reaction, the only difference being that the mass ratio of the carrier to the copper nitrate solution and the mass ratio of the carrier to the volume of the chloroplatinic acid solution in step (1) and step (3) were all 1:10 (g/ml) , the concentration of copper nitrate solution is 3.15*10 ^-2 M, and the concentration of chloroplatinic acid solution is 5.13*10 ^-3 M.

Example 5:

The method in Example 1 is used for the reaction, and the only difference is that the mass ratio of the carrier to the copper nitrate solution and the mass ratio of the carrier to the volume of the chloroplatinic acid solution in step (1) and step (3) are both 1:40 (g/ml) , the concentration of the copper nitrate solution is 9.84*10 ^-4 , and the concentration of the chloroplatinic acid solution is 3.84*10 ^-4 .

Embodiment 6:

The method in Example 1 was used for the reaction, the only difference being that the mass ratio of the carrier to the copper nitrate solution and the mass ratio of the carrier to the volume of the chloroplatinic acid solution in step (1) and step (3) were all 1:10 (g/ml) , the concentration of copper nitrate solution is 7.87*10 ^-3 M, and the concentration of chloroplatinic acid solution is 2.56*10 ^-3 M.

Embodiment 7:

The method in Example 1 is used for the reaction, and the only difference is that the mass ratio of the carrier to the copper nitrate solution and the mass ratio of the carrier to the volume of the chloroplatinic acid solution in step (1) and step (3) are both 1:40 (g/ml) , the concentration of copper nitrate solution is 1.97*10 ^-3 , and the concentration of chloroplatinic acid solution is 6.41*10 ^-4 M.

Embodiment 8:

The method in Example 1 was used for the reaction, the only difference being that the immersion time of step (1) and step (3) was 4 hours.

Embodiment 9:

The method in Example 1 was used for the reaction, the only difference being that the immersion time of step (1) and step (3) was 8 hours.

Example 10:

The reaction was carried out using the method of Example 1, the only difference being that the drying temperature of step (2) and step (4) was 100°C.

Example 11:

The reaction was carried out using the method of Example 1, the only difference being that the drying temperature of step (2) and step (4) was 140°C.

Example 12:

The method of Example 1 was used for the reaction, the only difference being that the drying time of step (2) and step (4) was 8 hours.

Example 13:

The method in Example 1 was used for the reaction, the only difference being that the drying time of step (2) and step (4) was 10 h.

Example 14:

The reaction was carried out using the method of Example 1, the only difference being that the calcination temperature of step (2) and step (4) was 400°C.

Example 15:

The reaction was carried out using the method of Example 1, the only difference being that the calcination temperature of step (2) and step (4) was 600°C.

Example 16:

The reaction was carried out using the method of Example 1, the only difference being that the calcination time of step (2) and step (4) was 2h.

Example 17:

The method in Example 1 was used for the reaction, the only difference being that the calcination time of step (2) and step (4) was 6h.

Example 18:

The reaction was carried out using the method of Example 1, the only difference being that the reduction temperature in step (6) was 500°C.

Example 19:

The reaction was carried out using the method of Example 1, the only difference being that the reduction temperature in step (6) was 600°C.

Example 20:

The method in Example 1 was used for the reaction, the only difference being that the reduction time of step (6) was 1 h.

Example 21:

The method in Example 1 was used for the reaction, the difference being that the reduction time of step (6) was 3 hours.

Example 22:

The reaction was carried out using the method in Example 1, the only difference being that the reaction temperature in step (7) was 500°C.

Example 23:

The reaction was carried out using the method of Example 1, the only difference being that the reaction temperature in step (7) was 700°C.

Example 24:

The reaction was carried out using the method of Example 1, the only difference being that the reaction space velocity in step (7) was 5h ^-1 .

Example 25:

The reaction was carried out using the method of Example 1, the only difference being that the reaction space velocity in step (7) was 10h ^-1 .

About above-mentioned embodiment 2-25 result and data discussion:

In the following discussion, the activity data of 4h after the reaction are used for comparison to investigate the influence of different condition parameters on the reaction performance of the catalyst.

(1) The effect of solution concentration, carrier mass and solution volume ratio on the reactivity of platinum-copper two-component propane dehydrogenation catalyst, see Table 2. Reaction condition is the same as embodiment 1,4,5,6,7.

Table 2. Effects of solution concentration, carrier mass and solution volume ratio on the reactivity of platinum-copper two-component catalysts

From the comparison of the above results, it can be seen that the ratio of the mass of the carrier to the volume of the solution will affect the activity of the prepared catalyst. When the ratio of the mass of the carrier to the volume of the solution is 1:30 (g/ml), the conversion of propane is 42.8%, and the selectivity of propylene It was 90.4%, and the propylene yield was 38.7%, reflecting the best propylene yield. In addition, the different catalyst activities obtained by different metal loadings are also listed in the table, and the catalyst with a mass fraction of Pt and Cu of 0.5% respectively reflects the optimal propylene yield.

(2) The effect of impregnation temperature on the reactivity of platinum-copper two-component propane dehydrogenation catalyst, see Table 3. Reaction condition is the same as embodiment 1,2,3.

Table 3. Effect of impregnation temperature on the reactivity of platinum-copper two-component catalysts

Immersion temperature (°C) Propane conversion rate (%) Propylene selectivity (%) Propylene yield (%) Example 40 40.1 91.2 36.6 2 60 42.8 90.4 38.7 1 80 44.7 85.1 38.0 3

From the above results, it can be seen that as the impregnation temperature increases, the conversion of propane increases, but the selectivity of propylene decreases, and the yield of propylene also shows a trend of first increasing and then decreasing. From the above three examples, at the impregnation temperature of 60°C, the propane conversion rate is 42.8%, the propylene selectivity is 90.4%, and the propylene yield rate is 38.7%, reflecting the best propylene yield.

(3) The effect of immersion time on the reactivity of platinum-copper two-component propane dehydrogenation catalyst, see Table 4. Reaction condition is the same as embodiment 1,8,9.

Table 4. Effect of immersion time on the reactivity of platinum-copper two-component catalysts

Immersion time (h) Propane conversion rate (%) Propylene selectivity (%) Propylene yield (%) Example 4 40.5 91.0 36.9 8 6 42.8 90.4 38.7 1 8 42.5 90.8 38.6 9

From the above results, it can be seen that with the increase of immersion time, the propane conversion rate will first increase and then remain stable. The propylene yield also showed a trend of rising first and then stabilizing.

(4) The effect of drying temperature on the reactivity of platinum-copper two-component propane dehydrogenation catalyst, see Table 5. Reaction condition is the same as embodiment 1,10,11.

Table 5. Effect of drying temperature on the reactivity of platinum-copper two-component catalysts

Drying temperature (°C) Propane conversion rate (%) Propylene selectivity (%) Propylene yield (%) Example 100 35.1 93.0 32.6 10 120 42.8 90.4 38.7 1 140 32.8 92.4 30.3 11

From the above results, it can be seen that with the increase of drying temperature, the conversion of propane will increase, but the selectivity will decrease, and the yield of propylene will increase with the increase of temperature.

(5) The effect of drying time on the reactivity of platinum-copper two-component propane dehydrogenation catalyst, see Table 6. Reaction condition is the same as embodiment 1,12,13.

Table 6. Effect of drying time on the reactivity of platinum-copper two-component catalysts

Drying time (h) Propane conversion rate (%) Propylene selectivity (%) Propylene yield (%) Example 8 40.1 91.2 36.6 12 10 39.8 90.7 36.1 13 12 42.8 90.4 38.7 1

From the above results, it can be seen that with the increase of drying time, the conversion of propane will increase, but the selectivity will decrease slightly. Under the condition of drying for 12h, the best yield of propane was obtained.

(6) The influence of calcination temperature on the reactivity of platinum-copper two-component propane dehydrogenation catalyst, see Table 7. Reaction condition is the same as embodiment 1,14,15.

Table 7. Effect of calcination temperature on the reactivity of platinum-copper two-component catalysts

Calcination temperature (°C) Propane conversion rate (%) Propylene selectivity (%) Propylene yield (%) Example 400 34.1 92.3 31.5 14 550 42.8 90.4 38.7 1 600 42.5 89.8 38.2 15

From the above results, it can be seen that with the increase of calcination temperature, the propane conversion rate and propylene production first increase and then basically remain stable. When the calcination temperature is 400℃, the conversion rate of propane is low. This is due to a slightly weaker interaction between the carrier and the active ingredient. at 550°C. The propane conversion rate of the catalyst has been greatly improved, the selectivity of propylene is slightly lower due to the good catalytic activity, and the propylene yield has been improved compared with 400 °C.

(7) The effect of calcination time on the reactivity of the platinum-copper two-component propane dehydrogenation catalyst is shown in Table 8. Reaction condition is the same as embodiment 1,16,17.

Table 8. Effect of calcination time on the reactivity of platinum-copper two-component catalysts

Roasting time (h) Propane conversion rate (%) Propylene selectivity (%) Propylene yield (%) Example 2 36.4 85.9 31.3 16 4 42.8 90.4 38.7 1 6 43.9 87.1 38.2 17

From the above results, it can be seen that with the increase of calcination time, the conversion rate of propane increases continuously, the selectivity of propylene increases and then decreases, and the propylene production first increases and then basically remains stable.

In the above examples, the preparation parameter conditions investigated in the preparation process of the platinum-copper two-component catalyst were compared. By comparing the activity data of the examples, the influence of each parameter condition on the performance of the catalyst can be obtained.

In the following examples, the focus is on comparing the difference in catalyst activity caused by different conditions in the application process of propane dehydrogenation to propylene.

(8) The effect of reduction temperature on the reactivity of platinum-copper two-component propane dehydrogenation catalyst, see Table 9. Reaction condition is the same as embodiment 1,18,19.

Table 9. Effect of reduction temperature on the reactivity of platinum-copper two-component catalysts

Reduction temperature (°C) Propane conversion rate (%) Propylene selectivity (%) Propylene yield (%) Example 500 33.8 92.0 31.1 18 550 42.8 90.4 38.7 1 600 43.1 90.0 38.8 19

From the above results, it can be seen that with the increase of the reduction temperature, the propane conversion rate and propylene production first increased and then basically remained stable, while the propylene selectivity decreased and then remained stable.

(9) The effect of reduction time on the reactivity of the platinum-copper two-component propane dehydrogenation catalyst is shown in Table 10. Reaction condition is the same as embodiment 1,20,21.

Table 10. Effect of reduction time on the reactivity of platinum-copper two-component catalysts

Recovery time (h) Propane conversion rate (%) Propylene selectivity (%) Propylene yield (%) Example 1 30.6 92.3 28.2 20 2 42.8 90.4 38.7 1 3 41.9 90.9 38.1 twenty one

It can be seen from the above results that when the reduction time is 2 hours, the best propane conversion rate and propylene yield are obtained, and the selectivity of propylene is above 90%.

(10) The influence of reaction temperature on the reactivity of platinum-copper two-component propane dehydrogenation catalyst, see Table 11. Reaction condition is the same as embodiment 1,22,23.

Table 11. Effect of reaction temperature on the reactivity of platinum-copper two-component catalysts

Reaction temperature (°C) Propane conversion rate (%) Propylene selectivity (%) Propylene yield (%) Example 500 15.7 95.3 15.0 twenty two 600 42.8 90.4 38.7 1 700 71.3 51.9 37.0 twenty three

It can be seen from the above results that as the reaction temperature increases, the conversion of propane increases continuously, the selectivity of propylene decreases, and the yield of propylene increases. Since the propane dehydrogenation reaction is a reversible reaction, it is limited by thermodynamic equilibrium. At 500°C, the propane conversion is very low, and as the temperature rises to 600°C, the propane conversion increases greatly. At 700°C, the conversion of propane reached 71.3%, but the selectivity of propylene decreased significantly. A reaction temperature of 600°C represents the highest propylene yield.

(11) The effect of propane mass space velocity on the reactivity of platinum-copper two-component propane dehydrogenation catalyst, see Table 12. Reaction condition is the same as embodiment 1,24,25.

Table 12. Effect of propane mass space velocity on the reactivity of platinum-copper two-component catalyst

Propane Mass Space Velocity (h ^-1 ) Propane conversion rate (%) Propylene selectivity (%) Propylene yield (%) Example 3 42.8 90.4 38.7 twenty four 5 35.1 93.7 32.9 1 10 27.5 94.3 25.9 25

From the above results, it can be seen that with the increase of the mass space velocity of propane, the conversion of propane decreases, the selectivity of propylene increases, and the yield of propylene decreases.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned specific implementations. The above-mentioned specific implementations are only illustrative and not restrictive. Under the enlightenment of the invention, without departing from the gist of the present invention and the scope of protection of the claims, many forms of specific changes can be made, and these all belong to the scope of protection of the present invention.

Claims (6)

1. a platinum-copper two-component catalyst, the catalyst is based on gamma-Al ₂ O ₃ as carrier, it is characterized in that, take platinum metal as active component, take copper metal as auxiliary agent; take catalyst gross mass as benchmark, wherein The mass percentage of platinum metal is 0.3-1.0%, and the mass percentage of copper metal is 0.25-2.0%; and, the catalyst is prepared by the following method: (1) Immerse the carrier γ-Al ₂ O ₃ powder in 9.84*10 ^-4 M-3.15*10 ^-2 M Cu(NO ₃ ) ₂ aqueous solution at 40-80°C for 4-8 hours, in which The ratio of the mass of the carrier to the volume of the Cu(NO ₃ ) ₂ aqueous solution is 1g:(10-40)ml; (2) Remove the solvent, dry at 100-140°C for 8-12h, and roast at 400-600°C for 2-6h to obtain a copper-supported catalyst; (3) Immerse the obtained copper-supported catalyst in 3.84*10 ^-4 M-5.13*10 ^-3 M H ₂ PtCl ₆ aqueous solution at 40-80°C for 4-8 hours, wherein the mass of the support is the same as that of the The volume ratio of H ₂ PtCl ₆ aqueous solution is 1g:(10-40)ml; (4) Remove the solvent, dry at 100-140°C for 8-12 hours, and roast at 400-600°C for 2-6 hours to obtain a platinum-copper dual-component catalyst. 2. a kind of platinum-copper two-component catalyst according to claim 1, is characterized in that, the mass percentage composition of described platinum metal is 0.5%, and the mass percentage composition of described copper metal is 0.5%; And the catalyst Prepared as follows: (1) Immerse the support γ-Al ₂ O ₃ powder in 2.62*10 ^-3 M Cu(NO ₃ ) ₂ aqueous solution at 60°C for 6 hours, wherein the mass of the support is the same as that of the Cu(NO ₃ ) ₂ The volume ratio of the aqueous solution is 1g:30ml; (2) Remove the solvent, dry at 120°C for 12h, and calcine at 550°C for 4h to obtain a copper-supported catalyst; (3) Immerse the obtained copper-supported catalyst in 8.54*10 ^-4 M H ₂ PtCl ₆ aqueous solution at 60°C for 6 hours, wherein the ratio of the mass of the support to the volume of the H ₂ PtCl ₆ aqueous solution is 1 g :30ml; (4) Remove the solvent, dry at 120°C for 12h, and calcinate at 550°C for 4h to obtain a platinum-copper dual-component catalyst. 3. a preparation method of platinum-copper two-component catalyst, is characterized in that, the method is carried out according to the following steps: (1) Immerse the carrier γ-Al ₂ O ₃ powder in 9.84*10 ^-4 M-3.15*10 ^-2 M Cu(NO ₃ ) ₂ aqueous solution at 40-80°C for 4-8 hours, in which The ratio of the mass of the carrier to the volume of the Cu(NO ₃ ) ₂ aqueous solution is 1g:(10-40)ml; (2) Remove the solvent, dry at 100-140°C for 8-12h, and roast at 400-600°C for 2-6h to obtain a copper-supported catalyst; (3) Immerse the obtained copper-supported catalyst in 3.84*10 ^-4 M-5.13*10 ^-3 M H ₂ PtCl ₆ aqueous solution at 40-80°C for 4-8 hours, wherein the mass of the support is the same as that of the The volume ratio of H ₂ PtCl ₆ aqueous solution is 1g:(10-40)ml; (4) Remove the solvent, dry at 100-140°C for 8-12 hours, and roast at 400-600°C for 2-6 hours to obtain a platinum-copper dual-component catalyst. 4. the preparation method of a kind of platinum-copper two-component catalyst according to claim 3 is characterized in that, the method is carried out according to the following steps: (1) Immerse the support γ-Al ₂ O ₃ powder in 2.62*10 ^-3 M Cu(NO ₃ ) ₂ aqueous solution at 60°C for 6 hours, wherein the mass of the support is the same as that of the Cu(NO ₃ ) ₂ The volume ratio of the aqueous solution is 1g:30ml; (2) Remove the solvent, dry at 120°C for 12h, and calcine at 550°C for 4h to obtain a copper-supported catalyst; (3) Immerse the obtained copper-supported catalyst in 8.54*10 ^-4 M H ₂ PtCl ₆ aqueous solution at 60°C for 6 hours, wherein the ratio of the mass of the support to the volume of the H ₂ PtCl ₆ aqueous solution is 1 g :30ml; (4) Remove the solvent, dry at 120°C for 12h, and calcinate at 550°C for 4h to obtain a platinum-copper dual-component catalyst. 5. a method for the production of propylene from propane dehydrogenation with platinum-copper dual-component catalyst as claimed in claim 1, is characterized in that, the method is carried out according to the following steps: (1) Press the powdery platinum-copper two-component catalyst into 20-40 mesh granular platinum-copper two-component catalyst; (2) Put the platinum-copper two-component catalyst after tableting into a fixed-bed reactor, pass in hydrogen-nitrogen mixed gas, and pre-reduce the platinum-copper two-component catalyst at 500-600°C by 1- 3h; the volume content of hydrogen in the hydrogen-nitrogen mixture is 10%; (3) After the reduction is completed, control the temperature of the fixed-bed reactor to 500-700°C, and feed the reaction gas into the fixed-bed reactor at a propane mass space velocity of 3-10h ^-1 for reaction. The reaction gas is composed of propane, hydrogen and nitrogen. , where the flow ratio of propane and hydrogen is 1:1, and nitrogen is the balance gas. 6. the method that the platinum-copper two-component catalyst according to claim 5 is used for propane dehydrogenation to produce propylene, it is characterized in that, the method is carried out according to the following steps: (1) Press the powdery platinum-copper two-component catalyst into 20-40 mesh granular platinum-copper two-component catalyst; (2) Put the platinum-copper two-component catalyst after tableting into a fixed-bed reactor, pass in a hydrogen-nitrogen mixture, and pre-reduce the platinum-copper two-component catalyst at 550°C for 2 hours; The volume content of hydrogen in the hydrogen-nitrogen mixture is 10%; (3) After the reduction is completed, control the temperature of the fixed-bed reactor to 600°C, and feed the reaction gas into the fixed-bed reactor at a propane mass space velocity of 3h ^-1 for reaction. The reaction gas is composed of propane, hydrogen and nitrogen, of which propane and The flow ratio of hydrogen is 1:1, and nitrogen is the balance gas.