A catalyst for the oxidative dehydrogenation of light alkanes to ethylene, its preparation method and application

Abstract

The present invention discloses a catalyst for the oxidative dehydrogenation of light alkanes to ethylene, its preparation method and application, belonging to the technical field of redox catalysts; the catalyst is composed of an active component, a co-active component and a carrier; wherein, the active component is a perovskite-like metal oxide SrCoO 3‑x , the co-active components are oxides of Ba, Mn and P, and the carrier is alumina or silica; the catalyst prepared by the present invention has high ethylene selectivity and activity stability, and the unique lattice oxygen type of SrCoO 3‑x guarantees the selectivity of ethylene; the introduced Ba and Mn oxides increase the ethane conversion rate and further improve the ethylene selectivity, and the introduced P oxide increases the activity stability of the catalyst.

Description

Technical Field

[0001] The present invention relates to the technical field of redox catalysts, and particularly to a catalyst for oxidative dehydrogenation of light alkanes to ethylene, a preparation method thereof, and an application thereof. Background Art

[0002] Dry gas is a gaseous by-product in the petrochemical production process, and its sources are extensive. Ethane is rich in dry gas from various sources, and the mass fraction of ethane in refinery catalytic cracking, delayed coking, hydrocracking, and PSA-analyzed dry gas is all above 15%. At present, after the refinery dry gas is concentrated in ethylene or directly utilized, the dry gas rich in ethane is mainly used as fuel, resulting in a great waste of resources. If these gases can be effectively utilized, it will bring new benefit growth points to petrochemical enterprises.

[0003] After the ethane in the dry gas is separated, it can produce ethylene through steam cracking technology. The principle is that the ethane molecule loses two hydrogen atoms to become an ethylene molecule and hydrogen: C2H6 → C2H4 + H2, ΔH 850℃ = 144 KJ / mol (the ΔH data is calculated by HSC chemistry software). This process is restricted by the thermodynamic equilibrium, with a high reaction temperature and a strong coking tendency. The cracking furnace needs to be frequently shut down to remove coke, seriously affecting the production efficiency. At present, many researchers remove the hydrogen generated in the process of oxidative dehydrogenation of dry gas to ethylene by burning it to form water in the reaction zone. This not only provides heat for the reaction itself but also promotes the reaction equilibrium. For the direct oxidative dehydrogenation method using O2 as the oxidant, there are disadvantages of over-oxidation, and in order to reduce the safety risk of the co-feed of ethane and oxygen, a large amount of inert gas is required for dilution, increasing the downstream separation load. Although the technology using the weak oxidant CO2 avoids the safety risk of oxygen co-feed, the conversion rate of CO2 itself is low and it is a strongly endothermic reaction, resulting in high downstream separation costs and operating energy consumption.

[0004] The chemical oxidative dehydrogenation method uses the lattice oxygen of the redox catalyst to react with the hydrogen generated by the dehydrogenation of ethane to form water, removing the hydrogen from the reaction zone, promoting the forward progress of the reaction equilibrium, and increasing the ethylene selectivity. Taking the oxide of metal Co as an example, the process formula for the production of ethylene by ethane CL-ODH is as follows:

[0005] Reaction: C2H6 + Co3O4 = C2H4 + H2O + 3CoO ΔH 750℃ = 101.4 KJ / mol

[0006] Regeneration: 3CoO + 1 / 2O2 = Co3O4 ΔH 750℃ = -205.3 KJ / mol

[0007] During this process, the in-situ combustion of hydrogen not only provides heat for the reaction itself, but also promotes the reaction equilibrium; compared with the direct oxidative dehydrogenation with gaseous oxygen, it avoids over-oxidation, reduces the yield of non-condensable gas, and reduces the separation cost and safety risk. It is a low-carbon, efficient and environmentally friendly technical route and has attracted the interest of many researchers.

[0008] The chemical looping oxidative dehydrogenation method involves the circulation of the catalyst in the oxidation reactor and the reduction regenerator. The circulating fluidized bed reactor is a suitable choice, but the redox catalyst with excellent selectivity and activity is still the key to this technology. Patent document CN110801828A discloses a catalyst for chemical looping oxidative dehydrogenation of ethane to olefins and its application in the oxidative dehydrogenation reaction of ethane, specifically relating to a lanthanum manganate perovskite-type catalyst for oxidative dehydrogenation of ethane to olefins, doped with base promoters (sodium, sodium phosphate, sodium tungstate) and non-base promoters (tungsten and phosphorus); patent document CN113289612A also discloses a perovskite-type catalyst, which is different in that it is doped with strontium salts and calcium salts; the purpose of using the perovskite-type lanthanum manganate catalyst in the above patents is that the presence of Mn +4 in lanthanum manganate can inhibit the reduction of electrophilic surface oxygen, inhibit the combustion of ethylene, and improve the ethylene yield. The doping of different salts is to improve the ethylene selectivity. Both have achieved certain technical effects, but there are still problems such as low catalyst activity, poor stability, especially low ethylene selectivity, and this catalyst is not suitable for fluidized bed reactors and regeneration systems.

[0009] Therefore, developing a redox catalyst with excellent selectivity, activity and fluidization performance, which can convert ethane in refinery dry gas into ethylene and improve the economic benefits of refineries, is of great significance. Summary of the Invention

[0010] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a catalyst for oxidative dehydrogenation of lower alkanes to ethylene, which has good reaction performance, the ethane conversion rate can reach 59.6%, and the ethylene selectivity is as high as 94.3%; at the same time, the catalyst has good wear resistance and activity stability, and is very suitable for the fluidized bed chemical looping oxidative dehydrogenation to ethylene system.

[0011] To achieve the above purpose, the present invention adopts the following technical solutions:

[0012] In the first aspect, the present invention provides a catalyst for oxidative dehydrogenation of lower alkanes to ethylene. Calculated by mass percentage, the catalyst is composed of the following substances: 40% - 80% active component, 5% - 50% co-active component and 15% - 45% carrier; wherein, the active component is a perovskite-like metal oxide SrCoO 3-x , and the co-active component is a mixed oxide of metal and non-metal.

[0013] As a further preference of the technical solution of the present invention, the perovskite-like metal oxide SrCoO 3-x where x is 0 to 0.5, and more preferably x is 0.48; the promoter components are oxides of Ba, Mn and P; the carrier is one or two of alumina and silica.

[0014] As a further preference of the technical solution of the present invention, by mass percentage, the catalyst is composed of the following substances: 40 to 80% of the perovskite-like metal oxide SrCoO 3-x , 2% to 15% of barium oxide, 2% to 15% of manganese oxide, 1% to 4% of phosphorus oxide and 15% to 45% of the carrier.

[0015] In the above technical solution, SrCoO 3-x is the main active component of the catalyst and has a stable oxygen defect structure. This oxygen defect structure endows it with a unique lattice oxygen type and a suitable transfer and release rate of lattice oxygen, specifically manifested as a relatively high ethylene selectivity; the introduced barium oxide (BaO) reacts with H2O generated by the in-situ combustion of hydrogen to form Ba(OH)2, further promoting the reaction equilibrium and increasing the ethane conversion rate; the introduced Mn oxide, due to having more valence state changes, can release oxygen through its own valence change to provide an oxygen reserve for the reaction process, that is, increasing the lattice oxygen storage and improving the ethane conversion rate; the role of introducing phosphorus oxide (P2O5) is to prevent the influence of water vapor on the specific surface area and pore volume of the catalyst carrier at high temperatures, increasing the activity stability of the catalyst. After multiple reaction regenerations, the reaction performance attenuation is not obvious. In addition, the appropriate addition of P will form AlPO4 on the surface of the carrier, weakening the interaction force between the carrier and the active components and ensuring the activity stability of the catalyst; the role of the carrier is to effectively disperse the active components, weaken the coalescence of the active components at high temperatures, ensure the effective diffusion of raw materials and products, increase the abrasion resistance of the catalyst, and reduce the loss during the use of the catalyst.

[0016] As a further preference of the technical solution of the present invention, the catalyst is microspherical, and its physical properties meet the following: the bulk density is 0.8 to 1.5 kg / m 3 , the specific surface area is 10 to 20 m 2 / g, and the attrition index is less than 3.0%.

[0017] As a further preference of the technical solution of the present invention, the catalyst is microspherical, and its particle size distribution meets the following: the proportion of particles less than 20 μm is not more than 7%, and the proportion of particles greater than 149 μm is not more than 8%.

[0018] As a further preference of the technical solution of the present invention, the active component precursor is a soluble salt containing Sr and Co; the co-active component precursor is a soluble salt or acid containing Ba, Mn and P; the carrier precursor is one or more of pseudoboehmite, aluminum sol and silica sol, and preferably aluminum sol.

[0019] As a further preference of the technical solution of the present invention, the active component precursor is one or more of cobalt nitrate, cobalt chloride, strontium nitrate and strontium chloride, and preferably cobalt nitrate and strontium nitrate; the co-active component precursor is one or more of barium nitrate, barium chloride, manganese nitrate, manganese chloride, phosphoric acid, ammonium phosphate and ammonium dihydrogen phosphate, and preferably barium nitrate, manganese nitrate and ammonium dihydrogen phosphate.

[0020] Second, the present invention provides a preparation method of the catalyst for oxidative dehydrogenation of the above-mentioned lower alkanes to ethylene, comprising the following steps:

[0021] (1) Dissolve the active component precursor fully in deionized water, then add a solid acid and an alcohol solvent, stir at a high speed in a water bath at 60-80 °C until the mixed system loses fluidity, then perform ultrasonic oscillation for 1-10 min, and then stand and age at room temperature until a wet gel is formed;

[0022] (2) Dry the wet gel obtained in step (1) at 90-120 °C for 20 min to 20 h, then first calcine at 180-340 °C for 2-5 h, and then calcine at 800-1000 °C for 4-12 h to obtain a powder; grind and screen the obtained powder to obtain the active component;

[0023] (3) Add the carrier precursor to deionized water, stir, then add the co-active component precursor and the active component obtained in step (2), stir and homogenize for 0.5-4 h to obtain a mixed slurry; spray-dry and form the obtained mixed slurry, and then dry and calcine the formed material to obtain the catalyst.

[0024] It can be understood that in the above technical solution, in order to obtain the perovskite-like metal oxide SrCoO 3-x , the molar ratio of the active component precursor based on the metal elements (Sr, Co) is 1:1; the carrier precursor is configured according to the mass content of the oxides (Al2O3, SiO2) in the catalyst being 15-45%, and the co-active component precursor is added according to the mass content of the Ba oxide in the catalyst being 2-15%, the mass content of the Mn oxide in the catalyst being 2-15%, and the mass content of the P oxide in the catalyst being 1-4%, respectively.

[0025] As a further preferred embodiment of the technical solution of the present invention, in step (1), the solid acid is one or more of oxalic acid and citric acid, preferably citric acid; the alcohol solvent is one or more of ethanol and ethylene glycol, preferably ethylene glycol; further preferably, the molar ratio of citric acid to cobalt / strontium metal ions is 1 to 4:1, and the molar ratio of ethylene glycol to citric acid is 1 to 4:1.

[0026] As a further preferred embodiment of the technical solution of the present invention, the rotation speed of the high-speed stirring agitator in step (1) is 700 to 2000 r / min; and the ultrasonic oscillation frequency is 30 to 55 kHz.

[0027] In the above technical solution, high-speed stirring can accelerate the volatilization of water and shorten the transformation process of sol to gel; appropriate ultrasonic oscillation is conducive to the dispersion of colloidal particles, control of appropriate grain size, and reduction of colloidal particle agglomeration.

[0028] As a further preferred embodiment of the technical solution of the present invention, the powder obtained in step (1) has a grain size of 15 to 40 nm; and the active component obtained consists of powder with a particle size of 2000 to 3000 mesh.

[0029] In the above technical scheme, the appropriate grain size (15-40nm) of the main active component is conducive to the transfer of lattice oxygen and increases the activity of the catalyst; the microsphere catalyst prepared by spray drying the main active component with a screening range of 2000-3000 mesh has a good particle size distribution and is particularly suitable for fluidized bed reaction and regeneration systems.

[0030] As a further preferred embodiment of the technical solution of the present invention, the drying conditions of step (2) are: first drying at 90°C, 100°C and 110°C in sequence for 20 minutes to 1 hour, and then drying at 120°C for 2 to 8 hours; the heating rate of the calcination process in step (2) is 1 to 5°C / min.

[0031] As a further preferred embodiment of the technical solution of the present invention, in step (3), the temperature of the spray drying furnace is 340-460°C, the temperature at the outlet of the drying tower is 140-240°C, and the pressure is 2.2-4.0 MPa; the drying conditions of the molding material are: drying at 110-130°C for 2-5 hours, and the roasting conditions are: heating to 800-1000°C at a rate of 1-5°C / min and maintaining for 4-6 hours.

[0032] In the third aspect, the present invention claims protection for the use of the above-mentioned catalyst in a fluidized bed oxidative dehydrogenation process for producing ethylene; it is understandable that the raw material of the present invention can be ethane-rich refinery dry gas, or ethane, propane or a mixture of the two, and the present invention has no specific limitation on the raw material.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The catalyst provided by the present invention has the characteristics of high alkane conversion rate and strong ethylene selectivity at the same time. It can convert ethane in refinery dry gas into ethylene, improving the economic benefits of refineries, which is of great significance. The catalyst also has good activity stability and anti-wear ability, and is particularly suitable for the circulating fluidized bed reaction regeneration system.

[0035] 2. Compared with the ABO3-type perovskite structure that satisfies the typical stoichiometric relationship, the main active component SrCoO of the catalyst of the present invention 3-x is oxygen-deficient. This lack of oxygen gives it a unique type of lattice oxygen, as well as a suitable transfer and release rate of lattice oxygen. Specifically, during the reaction process of the present invention, it shows a high ethylene selectivity. The introduction of co-active components such as barium and manganese can promote the reaction equilibrium, increase the lattice oxygen storage, and improve the alkane conversion rate. Adding phosphorus elements can prevent the influence of water vapor on the specific surface area and pore volume of the catalyst carrier at high temperatures. In addition, the appropriate addition of phosphorus will form AlPO4 on the surface of the carrier, weakening the interaction between the carrier and the active component, ensuring the activity stability of the catalyst. The role of the carrier is to effectively disperse the active component, weaken the coalescence of the active component at high temperatures, ensure the effective diffusion of raw materials and products, increase the anti-wear ability of the catalyst, and reduce the loss during the use of the catalyst. Under the synergistic effect of the active component, co-active component and carrier, the catalyst of the present invention obtains good reaction performance and physical properties, and can meet the requirements of the fluidized bed oxidative dehydrogenation to ethylene system.

[0036] 3. During the preparation process of the main active component, high-speed stirring can accelerate the volatilization of water and shorten the conversion process from sol to gel. Appropriate ultrasonic oscillation is beneficial to the dispersion of colloidal particles, control the appropriate grain size, and reduce the aggregation of colloidal particles. The appropriate grain size (15 - 40 nm) of the main active component is conducive to the transfer of lattice oxygen, increasing the activity of the catalyst. The microsphere catalyst prepared by spray drying and forming the main active component with a screening range of 2000 - 3000 mesh has a good particle size distribution and is particularly suitable for the reaction and regeneration system of the fluidized bed.

[0037] 4. The preparation process of the catalyst of the present invention is simple and easy to control, and the performance repeatability is relatively high after multiple preparations. Under the synergistic effect of the active component, co-active component and carrier, the prepared catalyst has good reaction performance. The ethane conversion rate can reach 59.6%, and the highest ethylene selectivity can reach 94.3%. The catalyst of the present invention has good wear resistance and stability. The catalyst attrition index is lower than 3.0%. It has good activity stability. After 100 regenerations, the conversion rate and selectivity decrease insignificantly (< 3%). BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is the XRD pattern of active component #1 and active component #2 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0039] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further elaborates on the present invention in conjunction with embodiments. Of course, the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] Although the steps in the present invention are arranged with reference numerals, they are not used to limit the order of the steps. Unless the order of the steps is clearly stated or the execution of a certain step requires other steps as a basis, the relative order of the steps can be adjusted. It can be understood that the term "and / or" used herein relates to and encompasses any and all possible combinations of one or more of the associated listed items.

[0041] It should be specifically noted that for those conditions not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer; for those reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0042] The present invention provides a catalyst for oxidative dehydrogenation of light alkanes to ethylene. By mass percentage, the catalyst is composed of the following substances: 40-80% active component, 5-50% co-active component, and 15-45% carrier; wherein, the active component is a perovskite-like metal oxide SrCoO 3-x , and the co-active component is a mixed oxide of metal and non-metal.

[0043] Specifically, the active component can account for 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% or any value within 40%-80%; the co-active component can account for 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% or any value within 5%-50%; the carrier can account for 15%, 20%, 25%, 30%, 35%, 40%, 45% or any value within 15%-45%.

[0044] Specifically, in the perovskite-like metal oxide SrCoO 3-x , x is 0-0.5, and can be 0, 0.1, 0.2, 0.3, 0.4, 0.5 or any value within 0-0.5; the co-active component is an oxide of Ba, Mn and P; the carrier is one or two of alumina and silica.

[0045] As a further preference of the technical solution of the present invention, by mass percentage, the catalyst is composed of the following substances: 40-80% perovskite-like metal oxide SrCoO 3-x , 2-15% barium oxide, 2-15% manganese oxide, 1-4% phosphorus oxide, and 15-45% carrier.

[0046] Specifically, SrCoO 3-x can account for 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% or any value within 40% - 80%; barium oxide can account for 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or any value within 2% - 15%; manganese oxide can account for 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or any value within 2% - 15%; phosphorus oxide can account for 1%, 2%, 3%, 4% or any value within 1% - 4%; the carrier can account for 15%, 20%, 25%, 30%, 35%, 40%, 45% or any value within 15% - 45%.

[0047] Specifically, the catalyst of the present invention is microspherical, and its physical properties meet: the bulk density is 0.8 - 1.5 kg / m 3 , the specific surface area is 10 - 20 m 2 / g, and the attrition index is less than 3.0%.

[0048] Specifically, the particle size distribution of the catalyst of the present invention meets: the proportion of particles < 20μm is not more than 7%, and the proportion of particles > 149μm is not more than 8%.

[0049] As a further preference of the technical solution of the present invention, the active component precursor is a soluble salt containing Sr and Co; the promoter active component precursor is a soluble salt or acid containing Ba, Mn, and P; the carrier precursor is one or more of pseudoboehmite, aluminum sol, and silica sol, preferably aluminum sol.

[0050] As a further preference of the technical solution of the present invention, the active component precursor is one or more of cobalt nitrate, cobalt chloride, strontium nitrate, and strontium chloride, preferably cobalt nitrate and strontium nitrate; the promoter active component precursor is one or more of barium nitrate, barium chloride, manganese nitrate, manganese chloride, phosphoric acid, ammonium phosphate, and ammonium dihydrogen phosphate, preferably barium nitrate, manganese nitrate, and ammonium dihydrogen phosphate.

[0051] The present invention also provides a preparation method of the above catalyst for oxidative dehydrogenation of lower alkanes to ethylene, comprising the following steps:

[0052] (1) Fully dissolve the active component precursor in deionized water, then add solid acid and alcohol solvent, and stir at high speed in a water bath at 60 - 80°C until the mixed system loses fluidity, then ultrasonically oscillate for 1 - 10 min, and then stand and age at room temperature until a wet gel is formed;

[0053] (2) Dry the wet gel obtained in step (1) at 90 - 120 °C for 20 min - 20 h, then first calcine it at 180 - 340 °C for 2 - 5 h, and then calcine it at 800 - 1000 °C for 4 - 12 h to obtain a powder; grind and screen the obtained powder to obtain the active component;

[0054] (3) Add the carrier precursor to deionized water, stir, then add the co - active component precursor and the active component obtained in step (2), and fully stir and homogenize for 0.5 - 4 h to obtain a mixed slurry; spray - dry and form the obtained mixed slurry, and then dry and calcine the formed material to obtain the catalyst.

[0055] Specifically, in step (1), the solid acid is one or more of oxalic acid and citric acid, preferably citric acid; the alcohol solvent is one or more of ethanol and ethylene glycol, preferably ethylene glycol; the molar ratio of citric acid to cobalt / strontium metal ions is 1 - 4:1, and the molar ratio of ethylene glycol to citric acid is 1 - 4:1.

[0056] Specifically, in step (1), the rotation speed of the high - speed stirring mixer is 700 - 2000 r / min, preferably 1000 r / min; the ultrasonic oscillation frequency is 30 - 55 kHz.

[0057] In the above technical solution, high - speed stirring can accelerate the volatilization of water and shorten the conversion process from sol to gel; appropriate ultrasonic oscillation is beneficial to the dispersion of colloidal particles, controlling the appropriate grain size, and reducing the agglomeration of colloidal particles.

[0058] Specifically, the grain size of the powder obtained in step (1) is 15 - 40 nm; the obtained active component is composed of powder with a particle size of 2000 - 3000 mesh.

[0059] In the above technical solution, an appropriate grain size (15 - 40 nm) of the main active component is beneficial to the transfer of lattice oxygen and increases the catalyst activity; the main active component with a screening range of 2000 - 3000 mesh has a good particle size distribution when made into a microsphere catalyst by spray - drying and forming, and is particularly suitable for the reaction and regeneration systems of fluidized beds.

[0060] Specifically, the drying conditions in step (2) are: first dry at 90 °C, 100 °C, and 110 °C in sequence for 20 min - 1 h, and then dry at 120 °C for 2 - 8 h; the heating rate during the calcination process in step (2) is 1 - 5 °C / min.

[0061] Specifically, in step (3), the furnace temperature for spray drying is 340 - 460°C, the outlet temperature of the drying tower is 140 - 240°C, and the pressure is 2.2 - 4.0 MPa; the drying conditions for the formed material are: drying at 110 - 130°C for 2 - 5 h, and the calcination conditions are: heating to 800 - 1000°C at a rate of 1 - 5°C / min and holding for 4 - 6 h.

[0062] Example 1

[0063] A preparation method of a catalyst for oxidative dehydrogenation of lower alkanes to ethylene, comprising the following steps:

[0064] (1) Dissolve 163.5 g of cobalt nitrate hexahydrate and 118.9 g of strontium nitrate in 550 mL of deionized water, and stir until fully mixed; then add 283 g of citric acid and 126 g of ethylene glycol, and stir thoroughly in a 70°C water bath at a rotation speed of 1000 r / min until the mixed system loses fluidity. Then, ultrasonically oscillate at 60°C and 35 kHz for 5 min, and then stand and age at room temperature until a wet gel is formed;

[0065] (2) Dry the wet gel obtained in step (1) at 90°C, 100°C, and 110°C for 40 min in sequence, and then dry at 120°C for 6 h to obtain a dry gel. Heat the dry gel in a muffle furnace at a rate of 2°C / min to 280°C and hold for 2 h, and then heat to 880°C at a rate of 2°C / min and hold for 6 h to obtain a powder; grind and screen the obtained powder, and take the powder with a screening range of 2000 - 3000 mesh as active component #1;

[0066] (3) Add 172 g of aluminum sol to 200 mL of deionized water, and while stirring, add 13.1 g of barium nitrate, 31.7 g of 50% manganese nitrate aqueous solution, 3.7 g of ammonium dihydrogen phosphate, and 100 g of active component #1 obtained in step (1). Stir and homogenize for 1.5 h to obtain a mixed slurry; spray dry and form the obtained mixed slurry (the furnace temperature for spray drying is 410°C, the outlet temperature of the drying tower is 180°C, and the pressure is 3.3 MPa), then dry the formed material at 120°C for 3 h, and then heat at a rate of 3°C / min to 880°C and hold for 4 h to obtain the catalyst C1 of the present invention.

[0067] Example 2

[0068] A preparation method of a catalyst for oxidative dehydrogenation of lower alkanes to ethylene, comprising the following steps:

[0069] (1) Obtain active component #1 according to the preparation method of Example 1;

[0070] (2) Add 109 g of aluminum sol to 180 mL of deionized water. While stirring, add 11.8 g of barium nitrate, 28.6 g of 50% manganese nitrate aqueous solution, 3.4 g of ammonium dihydrogen phosphate, and 100 g of the active component #1 obtained in step (1). Stir and homogenize thoroughly for 1.5 h to obtain a mixed slurry. Spray-dry the obtained mixed slurry (the furnace temperature of spray drying is 410 °C, the outlet temperature of the drying tower is 180 °C, and the pressure is 3.3 MPa). Then dry the formed material at 120 °C for 3 h, and then increase the temperature programatically at a rate of 3 °C / min to 880 °C and hold for 4 h to obtain the catalyst C2 of the present invention.

[0071] Example 3

[0072] A preparation method of a catalyst for oxidative dehydrogenation of lower alkanes to ethylene, comprising the following steps:

[0073] (1) Obtain the active component #1 according to the preparation method of Example 1;

[0074] (2) Add 89 g of aluminum sol to 180 mL of deionized water. While stirring, add 4.3 g of barium nitrate, 10.3 g of 50% manganese nitrate aqueous solution, 2.0 g of ammonium dihydrogen phosphate, and 100 g of the active component #1 obtained in step (1). Stir and homogenize thoroughly for 1.5 h to obtain a mixed slurry. Spray-dry the obtained mixed slurry (the furnace temperature of spray drying is 410 °C, the outlet temperature of the drying tower is 180 °C, and the pressure is 3.3 MPa). Then dry the formed material at 120 °C for 3 h, and then increase the temperature programatically at a rate of 3 °C / min to 880 °C and hold for 4 h to obtain the catalyst C3 of the present invention.

[0075] Example 4

[0076] A preparation method of a catalyst for oxidative dehydrogenation of lower alkanes to ethylene, comprising the following steps:

[0077] (1) Obtain the active component #1 according to the preparation method of Example 1;

[0078] (2) Add 225 g of aluminum sol to 140 mL of deionized water. While stirring, add 21.3 g of barium nitrate, 51.5 g of 50% manganese nitrate aqueous solution, 5.1 g of ammonium dihydrogen phosphate, and 50 g of the active component #1 obtained in step (1). Stir and homogenize thoroughly for 1.5 h to obtain a mixed slurry. Spray-dry the obtained mixed slurry (the furnace temperature of spray drying is 410 °C, the outlet temperature of the drying tower is 180 °C, and the pressure is 3.3 MPa). Then dry the formed material at 120 °C for 3 h, and then increase the temperature programatically at a rate of 3 °C / min to 880 °C and hold for 4 h to obtain the catalyst C4 of the present invention.

[0079] Example 5

[0080] A preparation method of a catalyst for oxidative dehydrogenation of light alkanes to ethylene, comprising the following steps:

[0081] (1) Obtain active component #1 according to the preparation method of Example 1;

[0082] (2) Add 140 g of aluminum sol to 180 mL of deionized water, and while stirring, add 28.6 g of 50% manganese nitrate aqueous solution, 3.4 g of ammonium dihydrogen phosphate, and 100 g of active component #1 obtained in step (1). Stir well and homogenize for 1.5 h to obtain a mixed slurry; Spray dry and form the obtained mixed slurry (the furnace temperature of spray drying is 410 °C, the outlet temperature of the drying tower is 180 °C, and the pressure is 3.3 MPa), then dry the formed material at 120 °C for 3 h, and then program the temperature to 880 °C at a rate of 3 °C / min and hold for 4 h to obtain catalyst C5 of the present invention.

[0083] Example 6

[0084] A preparation method of a catalyst for oxidative dehydrogenation of light alkanes to ethylene, comprising the following steps:

[0085] (1) Obtain active component #1 according to the preparation method of Example 1;

[0086] (2) Add 140 g of aluminum sol to 210 mL of deionized water, and while stirring, add 11.8 g of barium nitrate, 3.4 g of ammonium dihydrogen phosphate, and 100 g of active component #1 obtained in step (1). Stir well and homogenize for 1.5 h to obtain a mixed slurry; Spray dry and form the obtained mixed slurry (the furnace temperature of spray drying is 410 °C, the outlet temperature of the drying tower is 180 °C, and the pressure is 3.3 MPa), then dry the formed material at 120 °C for 3 h, and then program the temperature to 880 °C at a rate of 3 °C / min and hold for 4 h to obtain catalyst C6 of the present invention.

[0087] Example 7

[0088] A preparation method of a catalyst for oxidative dehydrogenation of light alkanes to ethylene, comprising the following steps:

[0089] (1) Obtain active component #1 according to the preparation method of Example 1;

[0090] (2) Add 120 g of aluminum sol to 180 mL of deionized water, and while stirring, add 11.8 g of barium nitrate, 28.6 g of 50% manganese nitrate aqueous solution, and 100 g of the active component #1 obtained in step (1). Stir well and homogenize for 1.5 h to obtain a mixed slurry; spray-dry and form the obtained mixed slurry (the furnace temperature of spray drying is 410 °C, the outlet temperature of the drying tower is 180 °C, and the pressure is 3.3 MPa). Then dry the formed material at 120 °C for 3 h, and then program the temperature to 880 °C at a rate of 3 °C / min and hold for 4 h to obtain the catalyst C7 of the present invention.

[0091] Example 8

[0092] A preparation method of a catalyst for oxidative dehydrogenation of lower alkanes to ethylene, comprising the following steps:

[0093] (1) The preparation conditions and the composition of the active component are the same as those of the active component #1 in Examples 1 to 7, except that the ultrasonic oscillation step is cancelled to obtain the active component #2;

[0094] (2) Add 109 g of aluminum sol to 180 mL of deionized water, and while stirring, add 11.8 g of barium nitrate, 28.6 g of 50% manganese nitrate aqueous solution, 3.4 g of ammonium dihydrogen phosphate, and 100 g of the active component #2 obtained in step (1). Stir well and homogenize for 1.5 h to obtain a mixed slurry; spray-dry and form the obtained mixed slurry (the furnace temperature of spray drying is 410 °C, the outlet temperature of the drying tower is 180 °C, and the pressure is 3.3 MPa). Then dry the formed material at 120 °C for 3 h, and then program the temperature to 880 °C at a rate of 3 °C / min and hold for 4 h to obtain the catalyst C8 of the present invention.

[0095] Example 9

[0096] A preparation method of a catalyst for oxidative dehydrogenation of lower alkanes to ethylene, comprising the following steps:

[0097] (1) The preparation conditions and the composition of the active component are the same as those of the active component #1 in Examples 1 to 7, except that the screening range of the powder is controlled between 1000 and 2000 meshes to obtain the active component #3;

[0098] (2) Add 109 g of aluminum sol to 180 mL of deionized water. While stirring, add 11.8 g of barium nitrate, 28.6 g of 50% manganese nitrate aqueous solution, 3.4 g of ammonium dihydrogen phosphate, and 100 g of the active component #3 obtained in step (1). Stir and homogenize for 1.5 h to obtain a mixed slurry. Spray-dry and form the obtained mixed slurry (the furnace temperature of spray drying is 410 °C, the outlet temperature of the drying tower is 180 °C, and the pressure is 3.3 MPa). Then dry the formed material at 120 °C for 3 h, and then increase the temperature to 880 °C at a rate of 3 °C / min and hold for 4 h to obtain the catalyst C9 of the present invention.

[0099] The XRD comparison of the active component #1 prepared in Examples 1-7 and the active component #2 prepared in Example 8 of the present invention is as follows Figure 1 shown; by analyzing the XRD spectra of Figure 1 using MDI JADE software, the average grain size of the active component #1 is 31 nm, and the average grain size of the active component #2 is 52 nm. Specifically, the main active component SrCoO of the present invention 3-x belongs to the hexagonal crystal system, and the unit cell parameters are a = 5.485, b = 5.485, The particle distribution is uniform and the surface is in a large-pore honeycomb shape.

[0100] The physical properties of the catalysts provided in Examples 1-9 of the present invention are shown in Table 1.

[0101] Table 1 Physical properties of the catalysts in Examples 1-9

[0102]

[0103]

[0104] After high-temperature calcination, metal oxides generally have a relatively low specific surface area (<5 m 2 / g); however, as can be seen from Table 1, the catalysts prepared by the method provided by the present invention have a relatively high specific surface area; at the same time, the catalysts of the present invention also have good abrasion resistance; the screening range of the catalysts of the present invention is better, and it is especially suitable for the reaction regeneration system of a circulating fluidized bed.

[0105] Evaluate the reaction performance of the catalysts C1-C9 in the reaction regeneration system for dehydrogenating ethane to ethylene in a fluidized bed. The reaction temperature is 650 °C, the temperature of the regenerator is 750 °C, the pressure of the reaction-regeneration system is 0.1 MPa, and the catalyst / dry gas = 15:1; the reaction performance results are shown in Table 2, and the reaction performance of the catalysts C1-C9 after 100 reaction-regeneration cycles is shown in Table 2.

[0106] Table 2 Reaction performance of the catalysts in Examples 1-9

[0107]

[0108] As can be seen from Table 2, the catalyst in the embodiment of the present invention has good reaction effect, the ethane conversion rate can reach 59.6%, and the ethylene selectivity can reach 94.3%; the introduction of Ba and Mn oxides significantly improves the ethane conversion rate and ethylene selectivity of the catalyst; by controlling the grain size and the screening range of the active components, the reaction performance of the catalyst can be improved; the introduction of P oxide significantly increases the activity stability of the catalyst; after the catalyst is regenerated 100 times, the reaction performance slightly decreases; under the synergistic effect of the active component, co-active component and carrier, the catalyst of the present invention has good reaction performance and physical properties, and can meet the requirements of the fluidized bed ethane chemical looping oxidative dehydrogenation to ethylene system.

[0109] Finally, it should be noted that the above embodiments do not limit the present invention in any form; for those skilled in the art, based on the present invention, some modifications and improvements can be made; therefore, all changes, modifications, substitutions, combinations, and simplifications made without departing from the essence and principle of the present invention shall be equivalent replacement methods and are all within the scope of protection required by the present invention.

Claims

1. A catalyst for the oxidative dehydrogenation of light alkanes to ethylene, characterized in that, The catalyst consists of the following substances by mass percentage: 40% - 80% active component, 5% - 50% co - active component, and 15% - 45% carrier; wherein, the active component is perovskite - like metal oxide SrCoO 3-x , and the co - active component is a mixed oxide of metal and non - metal; Among them, the perovskite-like metal oxide SrCoO 3-x where x is from 0 to 0.5 and x is not 0; the co-active components are oxides of Ba, Mn and P.

2. The catalyst for oxidative dehydrogenation of light alkanes to ethylene according to claim 1, wherein The carrier is one or two of alumina and silica.

3. The catalyst for oxidative dehydrogenation of light alkanes to ethylene according to claim 2, characterized in that, The catalyst consists of the following substances by mass percentage: 40% - 80% perovskite-like metal oxide SrCoO 3-x , 2% - 15% barium oxide, 2% - 15% manganese oxide, 1% - 4% phosphorus oxide, and 15% - 45% carrier.

4. The catalyst for oxidative dehydrogenation of light alkanes to ethylene according to claim 1, wherein The catalyst is microspherical, and its physical properties meet the following requirements: the bulk density is 0.8 - 1.5 kg / m 3 , the specific surface area is 10 - 20 m 2 / g, and the attrition index is less than 3.0%.

5. The catalyst for oxidative dehydrogenation of light alkanes to ethylene according to claim 4, characterized in that, The particle size distribution of the catalyst satisfies that the proportion of particles less than 20 μm is not more than 7%, and the proportion of particles greater than 149 μm is not more than 8%.

6. The catalyst for oxidative dehydrogenation of light alkanes to ethylene according to claim 3, characterized in that, The active component precursor is a soluble salt containing Sr and Co; the promoter active component precursor is a soluble salt or acid containing Ba, Mn, and P; the carrier precursor is one or more of pseudo-boehmite, aluminum sol, and silica sol.

7. A method for preparing a catalyst for oxidative dehydrogenation of light alkanes to ethylene according to any one of claims 1 to 6, characterized in that, It includes the following steps: (1) Fully dissolve the active component precursor in deionized water, then add solid acid and alcohol solvent, and stir at high speed in a water bath at 60-80 °C until the mixed system loses fluidity, then ultrasonically oscillate for 1-10 min, and then stand and age at room temperature until a wet gel is formed; (2) Dry the wet gel obtained in step (1) at 90-120 °C for 20 min-20 h, then first calcine at 180-340 °C for 2-5 h, and then calcine at 800-1000 °C for 4-12 h to obtain a powder; grind and screen the obtained powder to obtain the active component; (3) Add the carrier precursor to deionized water, stir, then add the promoter active component precursor and the active component obtained in step (2), and fully stir and homogenize for 0.5-4 h to obtain a mixed slurry; spray-dry the obtained mixed slurry into a shape, and then dry and calcine the shaped material to obtain the catalyst.

8. The preparation method of the catalyst for oxidative dehydrogenation of light alkanes to ethylene according to claim 7, characterized in that In step (1), the solid acid is one or two of oxalic acid and citric acid, and the alcohol solvent is one or two of ethanol and ethylene glycol; the rotation speed of the high-speed stirrer in step (1) is 700-2000 r / min; the ultrasonic oscillation frequency is 30-55 kHz.

9. The preparation method of the catalyst for oxidative dehydrogenation of light alkanes to ethylene according to claim 7 or 8, characterized in that, The grain size of the powder obtained in step (1) is 15-40 nm; the obtained active component is composed of powder with a particle size of 2000-3000 mesh.

10. The preparation method of the catalyst for oxidative dehydrogenation of light alkanes to ethylene according to claim 7, characterized in that, The drying conditions in step (2) are: first dry at 90 °C, 100 °C, and 110 °C for 20 min-1 h in sequence, and then dry at 120 °C for 2-8 h; the heating rate during the calcination process in step (2) is 1-5 °C / min.

11. The preparation method of the catalyst for oxidative dehydrogenation of lower alkanes to ethylene according to claim 7, characterized in that, The furnace temperature for spray drying in step (3) is 340-460 °C, the outlet temperature of the drying tower is 140-240 °C, and the pressure is 2.2-4.0 MPa; the drying conditions for the shaped material are: dry at 110-130 °C for 2-5 h, and the calcination conditions are: heat up to 800-1000 °C at a rate of 1-5 °C / min and hold for 4-6 h.

12. Application of a catalyst according to any one of claims 1-6 in the process of oxidative dehydrogenation to produce ethylene in a fluidized bed.

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