High-mechanical-strength heat storage material for process for preparing propylene through propane dehydrogenation and preparation method of high-mechanical-strength heat storage material

Abstract

The invention discloses a high-mechanical-strength heat storage material for a process for preparing propylene through catalytic dehydrogenation of propane and a preparation method of the high-mechanical-strength heat storage material, the heat storage material is a supported composite metal oxide xCuO / carrier, the carrier is Al2O3 + yMaOb, M is one or more of Ba, Mg, Mn, Zr, Ca, Ce, Bi, Co, Mo, Fe, Ni, Na, Nb and Sb, a is equal to 1-3, b is equal to 1-4, x is CuO carrying capacity and is equal to 10-30 wt%, and y is the doping amount of MaOb in the carrier and is equal to 10-30 wt%. The synthesized heat storage material has excellent mechanical strength, can be mixed with a catalyst to be used in a reaction process for preparing propylene through catalytic dehydrogenation of propane, can improve selectivity under the condition that the conversion rate of the catalyst is not changed, and is expected to prolong the service life of the catalyst and reduce the energy consumption of a device in industrial application.

Description

Technical Field

[0001] The invention is aimed at a propane catalytic dehydrogenation process, relates to a high-performance heat storage material for improving the temperature distribution of a catalyst bed in a fixed bed reactor and increasing the product yield, and a preparation method thereof, and belongs to the field of chemical industry. Background Art

[0002] Propylene is an important petrochemical raw material second only to ethylene, and is widely used in the production of polypropylene, butylene glycol, acrylonitrile, propylene oxide, epichlorohydrin, acetone, acrylic acid, etc. At present, propylene is mainly derived from ethylene co-production and catalytic cracking. In recent years, the development speed of propylene in my country has gradually exceeded that of ethylene. In 2017, the annual average growth rate of propylene equivalent demand in my country reached 7.6%, exceeding the growth rate of propylene production capacity. From the perspective of equivalent demand, the contradiction between propylene supply and demand has become increasingly prominent, resulting in the broad prospects for the PDH propylene production process to expand the source of propylene in recent years.

[0003] In the Catofin propane dehydrogenation process, the reaction takes place at the active sites on the catalyst surface and is accompanied by a strong endothermic process. Due to the difference in bed pressure drop caused by inconsistent fixed bed catalyst loading or the material deviation caused by the inability to completely symmetrical process piping layout, the fixed bed temperature distribution and temperature drop are generally not very uniform, which seriously affects the service life of the catalyst and the yield of propylene products. In order to improve the temperature distribution of the catalyst bed in the fixed bed reactor and increase the product yield, a metal oxide heat storage material is developed and mixed into the catalyst according to the characteristics of the propane dehydrogenation reaction. It can improve the selectivity while ensuring that the conversion rate remains unchanged, and can make the bed temperature distribution more uniform, extend the service life of the catalyst, and reduce the regeneration air inlet temperature or regeneration air flow, reducing the energy consumption of the device. Summary of the invention

[0004] The invention provides a heat storage material for a propane catalytic dehydrogenation to propylene reaction process with high mechanical strength and a preparation method thereof. The heat storage material has excellent mechanical strength and is mixed with a catalyst and applied to a propane catalytic dehydrogenation to propylene reaction, so that the selectivity can be improved while ensuring that the conversion rate remains unchanged, and more heat is released in the reduction stage and the air regeneration stage of the reaction, thereby ensuring that the heat is evenly distributed according to actual needs in industrial applications. The high mechanical strength of the developed heat storage material is more suitable for industrial applications, ensuring that the air inlet temperature or the regeneration air flow rate is greatly reduced during the industrial application process, and greatly reducing the energy consumption of the device.

[0005] A heat storage material for a propane catalytic dehydrogenation process to produce propylene, the heat storage material being a supported composite metal oxide xCuO / carrier, x being the CuO loading, and its value being 10-30wt%; the carrier being Al2O3+yM a O b, wherein M = one or more of Ba, Mg, Mn, Zr, Ca, Ce, Bi, Co, Mo, Fe, Ni, Na, Nb, Sb, a = 1 to 3, b = 1 to 4, y is M in the carrier a O b The doping amount is 10~30wt%.

[0006] Based on the above technical solution, the precursor material of the active component CuO is a soluble Cu nitrate, chloride, oxalate, oxychloride, acetate, citrate or metal acid ammonium salt.

[0007] Based on the above technical solution, preferably, the shape of the load heat storage material is one of columnar, spherical or sheet-like.

[0008] Another object of the present invention is to provide a method for preparing the heat storage material for the above-mentioned propane catalytic dehydrogenation process to produce propylene, comprising the following steps:

[0009] (1) Preparation of Al2O3+yM by mechanical mixing method a O b Carrier material;

[0010] (2) Al2O3+yM prepared in step (1) a O b The carrier material is calcined at 800-1500° C. for 3-10 hours in an air atmosphere;

[0011] (3) The active component precursor is loaded on Al2O3+yM by impregnation method a O b On the support material, the active component precursor salt / Al2O3+yM a O b Material;

[0012] (4) The active component precursor salt prepared in step (3) / Al2O3+yM a O b The material is calcined at 500-1000℃ for 3-10 hours in air atmosphere to obtain xCuO / Al2O3+yM with high mechanical strength. a O b Heat storage materials

[0013] Another object of the present invention is to provide the use of the above-mentioned high mechanical strength heat storage material in the direct dehydrogenation of propane to propylene reaction, wherein the heat storage material is mixed with a catalyst and used in the propane dehydrogenation to propylene reaction, and the weight ratio of the catalyst to the heat storage material when mixed is 1 to 6:1; the reaction conditions are: reaction pressure 40 to 60 kPa, reaction temperature 560 to 620 ° C, propane reaction space velocity 300 to 400 ml·g -1 ·h-1 Preferably, the reaction pressure is 50 kPa, the reaction temperature is 580 ° C, and the propane reaction space velocity is 320 ml g -1 ·h -1 The specific reaction conditions are as follows: the reaction is an automatic sequentially controlled 4-process, the first process is a propane dehydrogenation reaction at 40-60 kPa for 5-10 minutes; the second process is a water vapor purge at 40-60 kPa for 2-5 minutes; the third process is an air regeneration reaction at normal pressure for 5-10 minutes; the fourth process is a H2 reduction treatment reaction at 10-30 kPa for 5-10 minutes; preferably: the first process is a propane dehydrogenation reaction at 50 kPa for 7 minutes; the second process is a water vapor purge at 50 kPa for 2 minutes; the third process is an air regeneration reaction at normal pressure for 6 minutes; the fourth process is a H2 reduction treatment reaction at 20 kPa for 6 minutes.

[0014] Beneficial effects:

[0015] The heat storage material provided by the present invention has excellent mechanical strength, and after being mixed with a catalyst, it is used for the direct dehydrogenation of propane to produce propylene, thereby avoiding the pulverization phenomenon in its industrial application. The heat storage material with excellent mechanical strength prepared by the present invention shows excellent performance in the direct dehydrogenation of alkanes to produce propylene: the selectivity is improved while ensuring that the conversion rate remains unchanged, and more heat is released in the reduction stage and air regeneration stage of the reaction, so that the dehydrogenation reaction is better distributed in the entire catalyst bed, and it is expected to reduce the regeneration air inlet temperature or regeneration air flow in industrial applications, and reduce the energy consumption of the device.

[0016] The method provided by the invention has wide applicability, simplicity, low cost and good repeatability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The performance of catalytic dehydrogenation of propane to propylene in Example 1 and Comparative Example 1 for 1700 hours (● is Example 1; ○ is Comparative Example 1).

[0018] Figure 2 Comparison of the heat release in the regeneration stage (solid) and reduction stage (hollow) of catalytic dehydrogenation of propane to propylene for 1700 hours with and without adding heat storage material in Example 1 and Comparative Example 1 (where ●○ is the heat storage material of Example 1; ■□ is the heat storage material of Comparative Example 1; ★☆ is no heat storage material added). DETAILED DESCRIPTION

[0019] The following examples will further illustrate the present invention, but are not intended to limit the invention.

[0020] The propane catalytic dehydrogenation to propylene catalyst in the following embodiments and comparative examples is a homemade propane catalytic dehydrogenation to propylene catalyst, which is prepared with reference to Chinese patent application No. 202010076239.2.

[0021] Example 1

[0022] The Al2O3+20wt%MgO carrier was prepared by mechanical mixing and then calcined at 900℃ for 3 hours. Then, the 20wt%CuO / Al2O3+20wt%MgO thermal storage material was prepared by impregnation. A certain amount of copper nitrate was weighed and dissolved in deionized water according to the chemical formula. After stirring for 25 minutes, it was added to the Al2O3+20wt%MgO carrier. The solution was evaporated at 80℃ under stirring, and the obtained material was dried in an oven at 100℃ overnight. The thermal storage material after drying was calcined at 600℃ in a muffle furnace for 3 hours. The mechanical strength is shown in Table 1.

[0023] Example 2

[0024] The Al2O3+20wt%CeO2 carrier was prepared by mechanical mixing and then calcined at 900℃ for 3 hours. Then, the 20wt%CuO / Al2O3+20wt%CeO2 heat storage material was prepared by impregnation method. A certain amount of copper nitrate was weighed and dissolved in deionized water according to the chemical formula. After stirring for 25 minutes, it was added to the Al2O3+20wt%CeO2 carrier. The solution was evaporated at 80℃ under stirring, and the obtained material was dried in an oven at 100℃ overnight. The dried heat storage material was calcined at 600℃ in a muffle furnace for 3 hours. The mechanical strength is shown in Table 1.

[0025] Example 3

[0026] The Al2O3+20wt%Co3O4 carrier was prepared by mechanical mixing and then calcined at 900℃ for 3 hours. Then, the 20wt%CuO / Al2O3+20wt%Co3O4 heat storage material was prepared by impregnation. A certain amount of copper nitrate was weighed and dissolved in deionized water according to the chemical formula. After stirring for 25 minutes, it was added to the Al2O3+20wt%Co3O4 carrier. The solution was evaporated at 80℃ under stirring, and the obtained material was dried in an oven at 100℃ overnight. The dried heat storage material was calcined at 600℃ in a muffle furnace for 3 hours. The mechanical strength is shown in Table 1.

[0027] Example 4

[0028] The Al2O3+20wt% ZrO2 carrier was prepared by mechanical mixing and then calcined at 900℃ for 3 hours. Then, the 20wt% CuO / Al2O3+20wt% ZrO2 heat storage material was prepared by impregnation. A certain amount of copper nitrate was weighed and dissolved in deionized water according to the chemical formula. After stirring for 25 minutes, it was added to the Al2O3+20wt% ZrO2 carrier. The solution was evaporated at 80℃ under stirring, and the obtained material was dried in an oven at 100℃ overnight. The dried heat storage material was calcined at 600℃ in a muffle furnace for 3 hours. The mechanical strength is shown in Table 1.

[0029] Example 5

[0030] The Al2O3+20wt%Na2O carrier was prepared by mechanical mixing and then calcined at 900℃ for 3 hours. Then, the 20wt%CuO / Al2O3+20wt%Na2O thermal storage material was prepared by impregnation. A certain amount of copper nitrate was weighed and dissolved in deionized water according to the chemical formula. After stirring for 25 minutes, it was added to the Al2O3+20wt%Na2O carrier. The solution was evaporated at 80℃ under stirring, and the obtained material was dried in an oven at 100℃ overnight. The thermal storage material after drying was calcined at 600℃ in a muffle furnace for 3 hours. The mechanical strength is shown in Table 1.

[0031] Example 6

[0032] The heat storage materials of different compositions prepared in Examples 1 to 5 were mixed with the homemade propane catalytic dehydrogenation to propylene catalyst for direct propane dehydrogenation to propylene reaction. 10g of the formed catalyst was weighed and mixed with 3.8g of the heat storage material. The reaction raw gas was pure propane, the reaction pressure was 50kPa, the reaction temperature was 565℃, and the reaction space velocity was 320ml·g -1 ·h -1 The reaction is a 4-step process of automatic sequential control. The first step is propane dehydrogenation reaction at 50 kPa for 7 minutes; the second step is water vapor purge at 50 kPa for 2 minutes; the third step is air regeneration reaction at normal pressure for 6 minutes; the fourth step is H2 reduction treatment reaction at 20 kPa for 6 minutes. The reaction results are listed in Table 2. As can be seen from Table 2, the addition of certain heat storage materials can improve the selectivity while ensuring that the conversion rate remains basically unchanged, and release more heat in the reduction stage and air regeneration stage of the reaction.

[0033] Example 7

[0034] The heat storage material prepared in Example 1 was mixed with a propane catalytic dehydrogenation catalyst to produce propylene and used in a 1000-hour performance test of propane dehydrogenation to produce propylene. The results are shown in Figure 2The test process is as follows: 10g of the molded catalyst is weighed and mixed with 5g of the heat storage material prepared in Example 1. The reaction raw gas is pure propane, the reaction pressure is 50kPa, the reaction temperature is 580℃, and the reaction space velocity is 320ml·g -1 ·h -1 The reaction is an automatic sequential control of 4 processes. The first process is propane dehydrogenation reaction at 50kPa for 7min; the second process is water vapor purge at 50kPa for 2min; the third process is air regeneration reaction at normal pressure for 6min; the fourth process is H2 reduction treatment reaction at 20kPa for 6min. Obviously, Figure 1 It can be seen that after adding the heat storage material, the stability of the catalyst is improved, and the heat release in the regeneration stage and the reduction stage is significantly increased. Figure 2 This indicates that the addition of heat storage materials improves catalyst stability while ensuring activity, and that high heat release can be stored in the catalyst bed, greatly reducing the regeneration air temperature and energy consumption. More importantly, after 1,000 hours of reaction, the heat storage material did not pulverize, further verifying the high mechanical strength of the heat storage material and ensuring long-term high-strength performance in industrial use.

[0035] Comparative Example 1

[0036] The 20wt% CuO / Al2O3 heat storage material was prepared by the impregnation method. A certain amount of copper nitrate was weighed and dissolved in deionized water according to the chemical formula. After stirring for 25 minutes, it was added to the Al2O3 carrier. The solution was evaporated to dryness at 80°C under stirring, and the obtained material was dried in an oven at 100°C overnight. The dried heat storage material was calcined at 600°C in a muffle furnace for 3 hours. The mechanical strength is shown in Table 1.

[0037] Comparative Example 2

[0038] The heat storage material prepared in Comparative Example 1 was mixed with a propane catalytic dehydrogenation catalyst to produce propylene and used in a 1700-hour performance test of propane dehydrogenation to produce propylene. The results are shown in Figure 2 The test process is as follows: 10g of the molded catalyst is weighed and mixed with 5g of the heat storage material prepared in Comparative Example 1. The reaction raw gas is pure propane, the reaction pressure is 50kPa, the reaction temperature is 580℃, and the reaction space velocity is 320ml·g -1 ·h -1 The reaction is a 4-step process of automatic sequential control. The first step is propane dehydrogenation reaction at 50 kPa for 7 minutes; the second step is steam purge at 50 kPa for 2 minutes; the third step is air regeneration reaction at normal pressure for 6 minutes; the fourth step is H2 reduction treatment reaction at 20 kPa for 6 minutes. Obviously, the heat release in the regeneration stage and the reduction stage is significantly increased, but it is far lower than the result of Example 1. Figure 2In particular, after 1000 hours of reaction, the heat storage material was partially pulverized.

[0039] Table 1 Mechanical strength of heat storage materials in different embodiments (N) (each sample was tested 10 times)

[0040]

[0041] Table 2 Effect of the addition of heat storage materials on the heat release of propane dehydrogenation reaction in Examples 1 to 5

[0042]

Claims

1. A heat storage material for a process of producing propylene by catalytic dehydrogenation of propane, characterized in that: The heat storage material is xCuO / carrier, x is the CuO loading, and its value is 10-30wt%; the carrier is Al2O3+yM a O b , wherein M = one or more of Ba, Mg, Mn, Zr, Ca, Ce, Bi, Co, Mo, Fe, Ni, Na, Nb, Sb, a = 1 to 3, b = 1 to 4, y is M in the carrier a O b The doping amount is 10 to 30 wt%.

2. The heat storage material for the process of producing propylene by catalytic dehydrogenation of propane according to claim 1, characterized in that: The precursor material of the active component CuO is soluble Cu nitrate, chloride, oxalate, oxychloride, acetate, citrate or metal acid ammonium salt.

3. The heat storage material for the process of preparing propylene by catalytic dehydrogenation of propane according to claim 1, characterized in that: The heat storage material is in the shape of a column, a sphere or a sheet.

4. A method for preparing a heat storage material for a process of producing propylene by catalytic dehydrogenation of propane according to any one of claims 1 to 3, characterized in that: The steps include: (1) Preparation of Al2O3+yM by mechanical mixing method a O b Carrier material; (2) Al2O3+yM prepared in step (1) a O b The carrier material is calcined at 800-1500° C. for 3-10 hours in an air atmosphere; (3) The active component precursor is loaded on Al2O3+yM by impregnation method a O b On the support material, the active component precursor salt / Al2O3+yM a O b Material; (4) The active component precursor salt prepared in step (3) / Al2O3+yM a O b The material is calcined at 500-1000℃ for 3-10 hours in air atmosphere to obtain xCuO / Al2O3+yM with high mechanical strength. a O b Heat storage materials.

5. Use of the heat storage material according to any one of claims 1 to 3 in the direct dehydrogenation of propane to produce propylene.

6. The use according to claim 5, characterized in that: The heat storage material is mixed with a propane catalytic dehydrogenation catalyst for preparing propylene, and the weight ratio of the catalyst to the heat storage material is 1 to 6:

1.

7. The use according to claim 6, characterized in that: The reaction conditions are: reaction pressure 40-60 kPa, reaction temperature 560-620 °C, propane reaction space velocity 300-400 ml·g -1 ·h -1 .

8. The use according to claim 7, characterized in that: The specific reaction consists of four processes: the first process is propane dehydrogenation reaction at 40-60 kPa for 5-10 minutes; the second process is water vapor purge at 40-60 kPa for 2-5 minutes; the third process is air regeneration reaction at normal pressure for 5-10 minutes; the fourth process is H2 reduction treatment reaction at 10-30 kPa for 5-10 minutes.

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