Chromium catalyst for propane dehydrogenation as well as preparation method and application of chromium catalyst

Abstract

The invention discloses a chromium catalyst for propane dehydrogenation and a preparation method and application thereof, the catalyst is composed of an active component Cr2O3, an auxiliary agent, a modifier and an Al2O3-ZrO2 complex, the modifier is Y or Nd, and the auxiliary agent is at least one of Mn2O7, In2O3, CoO, OsO4 and MoO3. The catalyst is high in catalytic activity, strong in anti-coking capability, good in stability, low in cost and high in economical efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of propane dehydrogenation to propylene, and particularly relates to a chromium-based catalyst for propane dehydrogenation and a preparation method and application thereof. BACKGROUND

[0002] Propylene is an important basic chemical raw material, which is widely used in the manufacture of "three synthetic materials" such as plastics, synthetic rubber and synthetic fibers, as well as in the fields of coatings, medicines, electrical appliances and automobiles.

[0003] Currently, the catalysts commonly used in the propane dehydrogenation industry mainly include platinum-based and chromium-based catalysts. Although the platinum-based catalyst has high activity, it is expensive and has high cost. The chromium-based catalyst is relatively low in price, but has the problems of toxicity and fast coking deactivation, and needs to be regenerated once in a short reaction period of ten minutes. In addition, the high-temperature conditions required for propane dehydrogenation not only aggravate the coking deactivation of the catalyst, but also put high requirements on the production equipment, greatly limiting the production capacity of the equipment. Therefore, it is an urgent problem to be solved in the field to develop a chromium-alumina propane dehydrogenation catalyst that can effectively inhibit coking and prolong the regeneration cycle without reducing the activity of the catalyst.

[0004] In the existing related technologies, although there are many improvement schemes, there are still many deficiencies. Some patents optimize the performance of the catalyst by changing the preparation process or adding additives, but there is still a large space for improvement in the stability, anti-coking ability and activity retention of the catalyst.

[0005] Chinese patent CN 111468101 A provides a chromium-based catalyst and a preparation method and application thereof, in which a low-content chromium-based catalyst is modified by alkali metals, alkaline earth metals, transition metals and elements of the fourth main group. Although the chromium-based catalyst provided by the invention avoids pollution to the environment by reducing the chromium content, the catalyst utilization rate is too low, the conversion rate of propane is only 25% at most, and the selectivity of propylene is also not high.

[0006] Chinese patent CN 109289831 A uses titanium oxide doped ordered mesoporous alumina as a carrier and uses elements such as sodium and strontium as additives to prepare a chromium-based catalyst, which improves the activity of the catalyst, but the stability of the catalyst is poor, it is easy to coking deactivation at high temperature, and a template is used to prepare ordered pores in the process, which is high in cost and increases the preparation cost, which is not conducive to industrialization. SUMMARY

[0007] In view of the defects of the prior art, the present application provides a chromium-based catalyst for propane dehydrogenation and a preparation method and application thereof, which improves the composition and preparation method of the catalyst, solves the problem of fast coking and frequent regeneration of the existing chromium-based catalyst, effectively inhibits coking, prolongs the regeneration cycle, and improves the efficiency and economy of propane dehydrogenation without reducing the activity of the catalyst.

[0008] A chromium-based catalyst for propane dehydrogenation, which is composed of an active component Cr2O3, an additive, a modifier, and an Al2O3-ZrO2 complex, wherein the modifier is Y or Nd, and the additive is at least one of Mn2O7, In2O3, CoO, OsO4, and MoO3; In terms of 100% of the total mass of the catalyst, the mass content of each component in the catalyst is as follows: the active component is 5-20%; the modifier is 1.2-8.5%; When the additive contains Mn2O7, the content of Mn2O7 is 0.05-1%; when the additive contains In2O3, the content of In2O3 is 0.1-1.5%; when the additive contains CoO, the content of CoO is 0.4-3.5%; when the additive contains OsO4, the content of OsO4 is 0.1-1.2%; and when the additive contains MoO3, the content of MoO3 is 0.3-8.2%; The balance is the Al2O3-ZrO2 complex.

[0009] The modifier modifies the Al2O3-ZrO2 complex to form the carrier of the catalyst.

[0010] Preferably, in terms of 100% of the total mass of the Al2O3-ZrO2 complex, the content of Al2O3 is 58-75%, and the content of ZrO2 is 25-42%.

[0011] The preparation method of the chromium-based catalyst for propane dehydrogenation comprises the following steps: (S1) Preparation of a carrier: (1) A precursor of the modifier is added to a polyvinyl alcohol aqueous solution, stirred and dissolved to obtain a solution A component; (2) Al and Zr precursors are weighed, and a new fluorocarbon surfactant, a peptizing agent, and a pore-expanding agent are added thereto and stirred uniformly to obtain a component B; (3) The component B is added to the component A, stirred, and mixed uniformly to obtain a material C; (4) The material C is extruded into strips on a double-screw extruder, dried, placed in a microwave plasma generator for treatment to obtain the carrier; (S2) The carrier is immersed in a chromium nitrate aqueous solution, and then dried, calcined, and reduced in a mixed atmosphere of hydrogen and nitrogen; (S3) preparing an assistant precursor solution, immersing the product of step (2) in the solution, drying and calcining to obtain the catalyst.

[0012] Preferably, the total mass of the Al and Zr precursors and the mass ratio of the new fluorocarbon surfactant, the peptizing agent, the pore-expanding agent are 1: (0.005-0.02): (0.12-0.25): (0.04-0.15), and the mass ratio of component B and component A is 1: (0.08-0.5).

[0013] Preferably, the new fluorocarbon surfactant is perfluoroalkyl ethoxy ether alcohol or perfluorobutyl sulfonyl fluoride; The peptizing agent is any one of nitric acid solution, hydrochloric acid solution, acetic acid solution with a concentration of 5-15 wt%; The pore-expanding agent is at least one of methyl cellulose, urea, hexamethylenetetramine, ammonium acetate, and ethylenediamine.

[0014] Preferably, the processing condition of the microwave plasma generator is processing at a power of 400-600 W for 5-15 min.

[0015] Preferably, the temperature of the twin-screw extruder is 30-50℃, the pressure is 1-3.5 MPa, the extrusion die of the twin-screw extruder has a hole with a pore size of 2.2-3.7 mm, and the length of the cut strip of the extrusion strip forming is 2.5-5 mm.

[0016] Preferably, the precursor of the modifier is any one of yttrium carbonate, yttrium nitrate, yttrium phosphate, yttrium triflate, or any one of neodymium nitrate, neodymium chloride, and neodymium acetylacetone; The precursor of Al is a mixture of pseudo-boehmite powder and β-alumina powder mixed in any ratio; the precursor of Zr is zirconyl nitrate or zirconium nitrate; The assistant precursor is the nitrate salt corresponding to the assistant metal.

[0017] Preferably, the drying condition is drying at 85-115℃ for 8-15h; The impregnation condition is impregnation at 25-40℃ for 2-6h; The calcination condition is calcination at a temperature rising rate of 1.5-3℃ / min to 700-850℃ for 4-6h; The reduction condition is reduction at a temperature rising rate of 0.2-2℃ / min to 400-550℃ for 4-6h.

[0018] A method for preparing propylene by dehydrogenation of propane: loading a catalyst into a fixed bed reactor, passing in hydrogen and propane, and reacting at 570-620 DEG C and 0.05-0.15 MPa; wherein the mass space velocity of propane is 3-6.5 h -1 , the molar ratio of hydrogen to propane is 0.05-0.18; and the catalyst is the catalyst according to the application.

[0019] Advantages of the application: (1) High activity of the catalyst: by optimizing the composition and preparation method of the catalyst, the active phase Cr2O3-Nd2O3 or Cr2O3-Y2O3 is highly dispersed on the Al2O3-ZrO2 composite, and a good synergistic effect is formed between the active phase and the additives, effectively improving the catalytic activity of the catalyst for the propane dehydrogenation reaction; (2) Strong anti-coking ability: by modifying the Al2O3-ZrO2 composite with a modifier and passing in an appropriate amount of hydrogen during the reaction, the deposition of coke on the surface of the catalyst is significantly inhibited, the service life of the catalyst is greatly prolonged, the regeneration cycle is extended from tens of minutes to 3-4 h, the number of catalyst regeneration is reduced, and the production cost is reduced; (3) Good stability: by etching modification with microwave plasma technology, the carrier can produce defect sites instantaneously, which can anchor the modifier, and the addition of additives enhances the stability of the catalyst structure, so that the catalyst can still maintain good catalytic performance under long-term high-temperature reaction conditions, the activity decay is slow, and the continuity and stability of the production process are ensured; (4) Low cost and high economic efficiency: without using expensive platinum-based catalysts, the catalyst performance is improved, the energy consumption and catalyst loss in the production process are reduced, the production efficiency and yield of propylene are improved, and good economic benefits and market competitiveness are achieved. DETAILED DESCRIPTION

[0020] Example 1 1. A chromium-based catalyst for propane dehydrogenation, the catalyst consisting of the following components in an amount of 100%: active component Cr2O3 15%, additive Mn2O7 0.5%, modifier Y 6%, and the balance of Al2O3-ZrO2 composite; wherein the mass ratio of Al2O3 to ZrO2 in the Al2O3-ZrO2 composite is 60:40.

[0021] 2. A preparation method of the chromium-based catalyst for propane dehydrogenation, comprising the following steps: (S1) Preparation of the carrier: (1) Add yttrium carbonate to a 5wt% polyvinyl alcohol aqueous solution, stir and dissolve to obtain solution A component; (2) The pseudo-boehmite powder and the beta-alumina powder are weighed according to a mass ratio of 40:25, and then mixed with zirconium oxynitrate to obtain component B, wherein the total mass of the pseudo-boehmite powder, the beta-alumina powder and the zirconium oxynitrate is 1, and the mass ratio of the perfluoroalkyl ethoxy ether alcohol, the 10wt% nitric acid solution and the methyl cellulose is 0.01:0.15:0.08; (3) Component B is added into component A according to a mass ratio of 1:0.2, and then stirred and mixed uniformly to obtain material C; (4) The material C is extruded into a strip with a length of 3.5mm by using a mold with a pore diameter of 2.5mm on a double screw extruder at 40℃ and 2MPa, and then dried at 100℃ for 10h, and then etched in a microwave plasma generator at a power of 500W for 10min to obtain the carrier; (S2) A chromium nitrate aqueous solution containing 10wt% of chromium calculated as Cr2O3 is prepared, and the carrier is immersed in the chromium nitrate aqueous solution according to a solid-liquid ratio of 1g:2g, and then soaked at 30℃ for 4h, dried at 100℃ for 10h, and then heated to 800℃ at a rate of 2℃ / min and calcined for 5h, and then heated to 450℃ at a rate of 1℃ / min in a mixed gas atmosphere of hydrogen and nitrogen with a hydrogen volume ratio of 10% and reduced for 4.8h; (S3) A manganese nitrate aqueous solution is prepared, and the product of step (2) is immersed in the manganese nitrate aqueous solution according to a solid-liquid ratio of 1g:2g, and then soaked at 30℃ for 4h, dried at 100℃ for 10h, and then heated to 800℃ at a rate of 2℃ / min and calcined for 5h to obtain the catalyst.

[0022] Example 2 1. A chromium-based catalyst for propane dehydrogenation, the total mass of the catalyst being 100%, which is composed of the following components: active component Cr2O312%, auxiliary component In2O30.75%, modifier Y 5.5%, and the balance Al2O3-ZrO2 complex; wherein the mass ratio of Al2O3 to ZrO2 in the Al2O3-ZrO2 complex is 70:30.

[0023] 2. A preparation method of the chromium-based catalyst for propane dehydrogenation, comprising the following steps: (S1) Preparation of a carrier: (1) Yttrium nitrate is added into a 5wt% polyvinyl alcohol aqueous solution, and then stirred and dissolved to obtain a solution A component; (2) The pseudo-boehmite powder and the beta-alumina powder are weighed according to a mass ratio of 42:27, and then mixed with zirconium nitrate to obtain component B, wherein the total mass of the pseudo-boehmite powder, the beta-alumina powder and the zirconium nitrate is in a mass ratio of 1:0.015:0.18 to the perfluorobutylsulfonyl fluoride, the 10wt% hydrochloric acid solution and the urea at 0.06; (3) The component B is added into the component A according to a mass ratio of 1:0.4, and then stirred and mixed uniformly to obtain material C; (4) The material C is extruded into a strip with a length of 4.0mm by using a mold with a pore size of 3.0mm on a double-screw extruder at 35℃ and 1.5MPa, and then dried at 105℃ for 12h, and then etched in a microwave plasma generator at a power of 450W for 12min to obtain the carrier; (S2) A chromium nitrate aqueous solution containing 10wt% of chromium calculated as Cr2O3 is prepared, and the carrier is immersed in the chromium nitrate aqueous solution according to a solid-liquid ratio of 1g:2g, and then soaked at 35℃ for 3.5h, dried at 105℃ for 12h, and then calcined at 780℃ with a temperature rising rate of 2.5℃ / min for 5h, and then reduced at 500℃ with a temperature rising rate of 1.5℃ / min for 4.5h in a mixed gas atmosphere of hydrogen and nitrogen with a hydrogen volume ratio of 8%; (S3) An indium nitrate aqueous solution is prepared, and the product of step (2) is immersed in the indium nitrate aqueous solution according to a solid-liquid ratio of 1g:2g, and then soaked at 35℃ for 3.5h, dried at 105℃ for 12h, and then calcined at 780℃ with a temperature rising rate of 2.5℃ / min for 5h to obtain the catalyst.

[0024] Example 3 1. A chromium-based catalyst for dehydrogenation of propane, the total mass of the catalyst being 100%, consisting of the following components: active component Cr2O3 8%, auxiliary CoO 0.75%, modifier Nd 7.2%, and the balance Al2O3-ZrO2 complex; wherein the mass ratio of Al2O3 to ZrO2 in the Al2O3-ZrO2 complex is 65:35.

[0025] 2. A preparation method of the chromium-based catalyst for dehydrogenation of propane, comprising the following steps: (S1) Preparation of a carrier: (1) Neodymium nitrate is added into a 5wt% polyvinyl alcohol aqueous solution, and then stirred and dissolved to obtain a solution A component; (2) The pseudo-boehmite powder and the beta-alumina powder are weighed according to a mass ratio of 36:28, and then mixed with zirconyl nitrate to obtain component B, wherein the total mass of the pseudo-boehmite powder, the beta-alumina powder and the zirconyl nitrate is 1, and the mass ratio of the perfluoroalkyl ethoxy ether alcohol, the 7wt% acetic acid solution and the hexamethylenetetramine is 0.012:0.13:0.07; (3) Component B is added into component A according to a mass ratio of 1:0.1, and then stirred and mixed uniformly to obtain material C; (4) The material C is extruded into a strip with a length of 2.8mm by using a mold with a pore size of 3.5mm on a twin-screw extruder at 45℃ and 3.0MPa, and then dried at 90℃ for 12h, and then etched in a microwave plasma generator at a power of 425W for 13min to obtain the carrier; (S2) A chromium nitrate aqueous solution containing 10wt% of chromium calculated as Cr2O3 is prepared, and the carrier is immersed in the chromium nitrate aqueous solution according to a solid-liquid ratio of 1g:2g, and then soaked at 38℃ for 4.5h, dried at 95℃ for 14h, and then heated to 820℃ at a rate of 2.2℃ / min, and then calcined for 4.8h, and then heated to 480℃ at a rate of 1.4℃ / min in a mixed gas atmosphere of hydrogen and nitrogen with a hydrogen volume ratio of 9%, and then reduced for 5h; (S3) A cobalt nitrate aqueous solution is prepared, and the product of step (2) is immersed in the cobalt nitrate aqueous solution according to a solid-liquid ratio of 1g:2g, and then soaked at 38℃ for 4.5h, dried at 100℃ for 12.5h, heated to 820℃ at a rate of 2.2℃ / min, and then calcined for 4.8h to obtain the catalyst.

[0026] Example 4 1. A chromium-based catalyst for dehydrogenation of propane, wherein the total mass of the catalyst is 100%, and the catalyst is composed of the following components: active component Cr2O318%, adjuvant OsO40.82%, modifier Nd 6.6%, and the balance of Al2O3-ZrO2 composite; wherein the mass ratio of Al2O3 to ZrO2 in the Al2O3-ZrO2 composite is 75:25.

[0027] 2. A preparation method of the chromium-based catalyst for dehydrogenation of propane, comprising the following steps: (S1) Preparation of a carrier: (1) Neodymium chloride is added into a 5wt% polyvinyl alcohol aqueous solution, and then stirred and dissolved to obtain a solution A component; (2) Weigh boehmite powder and β-alumina powder at a mass ratio of 50:25, mix them evenly with zirconium oxynitrate, add perfluorobutyl sulfonyl fluoride, 6wt% nitric acid solution and ammonium acetate, stir evenly to obtain component B; wherein, the mass ratio of the total mass of boehmite powder, β-alumina powder and zirconium oxynitrate to the mass ratio of perfluorobutyl sulfonyl fluoride, 6wt% nitric acid solution and ammonium acetate is 1:0.007:0.16:0.08; (3) According to the mass ratio of component B to component A of 1:0.08, add component B to component A, stir and mix evenly to obtain material C; (4) Material C is extruded into a strip with a length of 3.5 mm using a die with a diameter of 2.6 mm on a twin-screw extruder at 36°C and 2.7 MPa. After drying at 85°C for 15 h, it is placed in a microwave plasma generator and etched at 525 W power for 11 min to obtain the carrier. (S2) Prepare an aqueous solution of chromium nitrate with a chromium content of 10 wt% based on Cr2O3. Immerse the support in the aqueous solution of chromium nitrate at a solid-liquid ratio of 1 g: 2 g, immerse at 26 °C for 5.2 h, dry at 95 °C for 12.5 h, then calcine at 770 °C at a rate of 1.7 °C / min for 5.5 h, and reduce at 450 °C at a rate of 0.3 °C / min for 5.5 h in a mixed atmosphere of hydrogen and nitrogen with a hydrogen volume ratio of 8.5%. (S3) Prepare an osmium nitrate aqueous solution, and impregnate the product of step (2) in it with a solid-liquid ratio of 1g:2g. Impregnate at 26°C for 5.2h, dry at 95°C for 12.5h, and calcine at 770°C for 5h by increasing the temperature at 1.7°C / min to obtain the catalyst.

[0028] Example 5 1. A chromium-based catalyst for propane dehydrogenation, wherein the catalyst, by weight (100%), comprises the following components: 12% active component Cr2O3, 8.2% auxiliary agent MoO3, 1.2% modifier Nd, and the balance Al2O3-ZrO2 composite; wherein the mass ratio of Al2O3 to ZrO2 in the Al2O3-ZrO2 composite is 58:42.

[0029] 2. The method for preparing the chromium-based catalyst for propane dehydrogenation includes the following steps: (S1) Preparation of the carrier: (1) Add neodymium acetylacetone to a 5 wt% polyvinyl alcohol aqueous solution and stir to dissolve to obtain solution component A; (2) The pseudo-boehmite powder and the beta-alumina powder are weighed according to a mass ratio of 35:20, and then mixed with zirconyl nitrate to obtain component B, wherein the total mass of the pseudo-boehmite powder, the beta-alumina powder and the zirconyl nitrate is 1, and the mass ratio of the perfluoroalkyl ethoxy ether alcohol, the 5wt% acetic acid solution and the ethylenediamine is 0.012:0.21:0.11; (3) Component B is added into component A according to a mass ratio of 1:0.5, and then stirred and mixed to obtain material C; (4) The material C is extruded into a strip with a length of 2.6mm by using a mold with a pore size of 3.6mm on a double screw extruder at 46℃ and 1.5MPa, and then dried at 112℃ for 9h, and then etched in a microwave plasma generator at a power of 580W for 6min to obtain the carrier; (S2) A chromium nitrate aqueous solution containing 10wt% of chromium calculated as Cr2O3 is prepared, and the carrier is immersed in the chromium nitrate aqueous solution according to a solid-liquid ratio of 1g:2g, and then soaked at 40℃ for 2h, dried at 105℃ for 12h, and then calcined at 830℃ with a temperature rising rate of 1.8℃ / min for 5h, and then reduced at 520℃ with a temperature rising rate of 1.8℃ / min for 5h in a mixed gas atmosphere of hydrogen and nitrogen, wherein the volume ratio of hydrogen is 10.5%; (S3) A molybdenum nitrate aqueous solution is prepared, and the product of step (2) is immersed in the molybdenum nitrate aqueous solution according to a solid-liquid ratio of 1g:2g, and then soaked at 40℃ for 2h, dried at 105℃ for 12h, and then calcined at 830℃ with a temperature rising rate of 1.8℃ / min for 5h to obtain the catalyst.

[0030] Example 6 1. A chromium-based catalyst for propane dehydrogenation, wherein the total mass of the catalyst is 100%, and the catalyst is composed of the following components: an active component Cr2O3 12%, an auxiliary Mn2O7 0.06%, an auxiliary OsO4 0.58%, a modifier Nd 8.5%, and the balance Al2O3-ZrO2 complex; wherein the mass ratio of Al2O3 to ZrO2 in the Al2O3-ZrO2 complex is 60:40.

[0031] 2. A preparation method of the chromium-based catalyst for propane dehydrogenation, comprising the following steps: (S1) Preparation of a carrier: (1) Neodymium nitrate is added into a 5wt% polyvinyl alcohol aqueous solution, and then stirred and dissolved to obtain a solution A component; (2) The pseudo-boehmite powder and the beta-alumina powder are weighed according to a mass ratio of 40:20, and then mixed with zirconium oxynitrate to obtain component B, wherein the total mass of the pseudo-boehmite powder, the beta-alumina powder and the zirconium oxynitrate is 1, and the mass ratio of the perfluoroalkyl ethoxy ether alcohol, the 15wt% acetic acid solution and the ethylenediamine is 0.005:0.12:0.04; (3) Component B is added into component A according to a mass ratio of 1:0.25, and then stirred and mixed to obtain material C; (4) The material C is extruded into a strip with a length of 2.5mm by using a mold with a pore size of 2.2mm on a double screw extruder at 30℃ and 3.5MPa, and then dried at 85℃ for 15h, and then etched in a microwave plasma generator at a power of 400W for 15min to obtain the carrier; (S2) A chromium nitrate aqueous solution containing 10wt% of chromium calculated as Cr2O3 is prepared, and the carrier is immersed in the chromium nitrate aqueous solution according to a solid-liquid ratio of 1g:2g, and then soaked at 40℃ for 2h, dried at 85℃ for 15h, and then heated to 850℃ at a rate of 1.5℃ / min, and then calcined for 4h, and then heated to 550℃ at a rate of 0.2℃ / min in a mixed gas atmosphere of hydrogen and nitrogen with a hydrogen volume ratio of 5%, and then reduced for 4h; (S3) A mixed aqueous solution of manganese nitrate and osmium nitrate is prepared, and the product of step (2) is immersed in the mixed aqueous solution according to a solid-liquid ratio of 1g:2g, and then soaked at 40℃ for 2h, dried at 85℃ for 15h, and then heated to 850℃ at a rate of 1.5℃ / min, and then calcined for 4h to obtain the catalyst.

[0032] Example 7 1. A chromium-based catalyst for dehydrogenation of propane, wherein the total mass of the catalyst is 100%, and the catalyst is composed of the following components: active component Cr2O3 5%, adjuvant In2O3 0.1%, adjuvant OsO4 0.1%, adjuvant MoO3 0.3%, modifier Y4%, and the balance Al2O3-ZrO2 composite; wherein the mass ratio of Al2O3 to ZrO2 in the Al2O3-ZrO2 composite is 75:25.

[0033] 2. A preparation method of the chromium-based catalyst for dehydrogenation of propane, comprising the following steps: (S1) Preparation of a carrier: (1) Yttrium phosphate is added into a 5wt% polyvinyl alcohol aqueous solution, and then stirred and dissolved to obtain a solution A component; (2) The pseudo-boehmite powder and the beta-alumina powder are weighed according to a mass ratio of 55:20, and then mixed with zirconyl nitrate to obtain component B; the pseudo-boehmite powder, the beta-alumina powder and the zirconyl nitrate are weighed, and then perfluoroalkylethoxy ether alcohol, 12wt% acetic acid solution and hexamethylenetetramine are added thereto and stirred uniformly; wherein the mass ratio of the total mass of the pseudo-boehmite powder, the beta-alumina powder and the zirconyl nitrate to the mass of the perfluoroalkylethoxy ether alcohol, the 12wt% acetic acid solution and the hexamethylenetetramine is 1:0.02:0.25:0.15; (3) Component B is added to component A according to a mass ratio of 1:0.38, and then stirred and mixed uniformly to obtain material C; (4) The material C is extruded into a strip with a length of 5mm by using a mold with a pore size of 3.7mm on a twin-screw extruder at 50℃ and 1MPa, and then dried at 115℃ for 8h, and then etched in a microwave plasma generator at a power of 600W for 5min to obtain the carrier; (S2) A chromium nitrate aqueous solution containing 10wt% of chromium calculated as Cr2O3 is prepared, and the carrier is immersed in the chromium nitrate aqueous solution at a solid-liquid ratio of 1g:2g, and then soaked at 25℃ for 6h, dried at 115℃ for 8h, and then calcined at 700℃ with a temperature rising rate of 3℃ / min for 6h, and then reduced at 550℃ with a temperature rising rate of 0.2℃ / min for 4h in a mixed gas atmosphere of hydrogen and nitrogen with a hydrogen volume ratio of 5%; (S3) An aqueous solution of a mixture of indium nitrate, osmium nitrate and molybdenum nitrate is prepared, and the product of step (2) is immersed in the aqueous solution at a solid-liquid ratio of 1g:2g, and then soaked at 25℃ for 6h, dried at 115℃ for 8h, and then calcined at 700℃ with a temperature rising rate of 3℃ / min for 6h to obtain the catalyst.

[0034] Example 8 1. A chromium-based catalyst for dehydrogenation of propane, the total mass of the catalyst being 100%, consisting of the following components: active component Cr2O3 20%, auxiliary In2O3 1.5%, auxiliary CoO 3.5%, modifier Y 8%, and the balance being an Al2O3-ZrO2 composite; wherein the mass ratio of Al2O3 to ZrO2 in the Al2O3-ZrO2 composite is 60:40.

[0035] 2. A preparation method of the chromium-based catalyst for dehydrogenation of propane, comprising the following steps: (S1) Preparation of a carrier: (1) Yttrium triflate is added to a 5wt% polyvinyl alcohol aqueous solution and stirred to dissolve, to obtain solution A component; (2) Pseudoboehmite powder and beta-alumina powder are weighed according to a mass ratio of 35:20, mixed with zirconyl nitrate, and then full-fluoroalkyl ethoxy ether alcohol, 12wt% acetic acid solution, and pore-expanding agent, which is hexamethylenetetramine and ammonium acetate, are added thereto and stirred uniformly to obtain component B; wherein the total mass of the pseudoboehmite powder, beta-alumina powder, and zirconyl nitrate and the mass of the full-fluoroalkyl ethoxy ether alcohol, 12wt% acetic acid solution, and pore-expanding agent are in a ratio of 1:0.014:0.24:0.1; (3) Component B is added to component A according to a mass ratio of 1:0.45, stirred, and mixed uniformly to obtain material C. (4) Material C is extruded into a strip with a length of 5mm on a twin-screw extruder at 50℃ and 1MPa using a die with a pore diameter of 3.7mm, dried at 115℃ for 8h, and etched in a microwave plasma generator at a power of 600W for 5min to obtain the carrier. (S2) A chromium nitrate aqueous solution containing 10wt% of chromium calculated as Cr2O3 is prepared, the carrier is immersed in the chromium nitrate aqueous solution at a solid-liquid ratio of 1g:2g, and immersed at 25℃ for 6h, dried at 115℃ for 8h, and then heated to 700℃ at a rate of 3℃ / min and calcined for 6h, and then heated to 550℃ at a rate of 0.2℃ / min in a mixed gas atmosphere of hydrogen and nitrogen with a hydrogen volume ratio of 5% and reduced for 4h. (S3) An aqueous mixed solution of indium nitrate and cobalt nitrate is prepared, the product of step (2) is immersed therein at a solid-liquid ratio of 1g:2g, and immersed at 25℃ for 6h, dried at 115℃ for 8h, and then heated to 700℃ at a rate of 3℃ / min and calcined for 6h to obtain the catalyst.

[0036] Example 9 1. A chromium-based catalyst for dehydrogenation of propane, the total mass of the catalyst being 100%, consisting of the following components: active component Cr2O3 20%, auxiliary Mn2O7 1%, auxiliary CoO 0.4%, auxiliary OsO4 1.2%, modifier Y 8%, and the balance Al2O3-ZrO2 complex; wherein the mass ratio of Al2O3 to ZrO2 in the Al2O3-ZrO2 complex is 60:40.

[0037] 2. In the preparation method, in step (S3), an aqueous mixed solution containing manganese nitrate, cobalt nitrate, and osmium nitrate is prepared, and the other steps are the same as in Example 1.

[0038] Comparative Example 1 No modifier Y is added, in the preparation method, no yttrium carbonate is added in step (1), and the other steps are the same as in Example 1.

[0039] Comparative Example 2 Without adding the aid Mn2O7, in the preparation method, in step (S3), water is used instead of the Mn2O7 aid solution, and the rest is the same as in Example 1.

[0040] Comparative Example 3 Step (4) is not treated in a microwave plasma generator, and the rest is the same as in Example 1.

[0041] Catalytic performance detection A method for preparing propylene by dehydrogenation of propane: the catalyst is loaded into a fixed bed reactor, hydrogen and propane are introduced, and the reaction is carried out at 570℃, 0.1MPa; wherein the mass space velocity of propane is 3h -1 , the molar ratio of hydrogen to propane is 0.05, and the results are shown in Table 1.

[0042] Table 1 Reaction results .

Claims

1. A chromium-based catalyst for dehydrogenation of propane, characterized by: The catalyst is composed of active component Cr2O3, auxiliary agent, modifier Y or Nd, and Al2O3-ZrO2 complex, and the auxiliary agent is at least one of Mn2O7, In2O3, CoO, OsO4 and MoO3; The mass content of each component in the catalyst is as follows: active component 5-20%, modifier 1.2-8.5%, and Al2O3-ZrO2 complex 75-85%, based on the total mass of the catalyst. When the auxiliary agent contains Mn2O7, the content of Mn2O7 is 0.05-1%; when the auxiliary agent contains In2O3, the content of In2O3 is 0.1-1.5%; when the auxiliary agent contains CoO, the content of CoO is 0.4-3.5%; when the auxiliary agent contains OsO4, the content of OsO4 is 0.1-1.2%; and when the auxiliary agent contains MoO3, the content of MoO3 is 0.3-8.2%. The rest is Al2O3-ZrO2 complex.

2. The chromium-based catalyst for dehydrogenation of propane according to claim 1, characterized by: The content of Al2O3 in the Al2O3-ZrO2 complex is 58-75%, and the content of ZrO2 is 25-42%, based on the total mass of the Al2O3-ZrO2 complex.

3. The method for producing a chromium-based catalyst for dehydrogenation of propane according to claim 1 or 2, characterized by: The method comprises the following steps: (S1) preparing a carrier: (1) adding a precursor of the modifier into a polyvinyl alcohol aqueous solution, stirring and dissolving to obtain component A; (2) weighing precursors of Al and Zr, adding a new fluorocarbon surfactant, a peptizing agent and a pore-expanding agent into the precursors, and stirring to obtain component B; (3) adding component B into component A, stirring and mixing to obtain material C; (4) extruding material C into a strip shape on a double-screw extruder, drying, and processing in a microwave plasma generator to obtain the carrier; (S2) immersing the carrier in an aqueous solution of chromium nitrate, and then drying and calcining, and reducing in a mixed atmosphere of hydrogen and nitrogen; (S3) preparing a solution of a precursor of the auxiliary agent, immersing the product of step (2) in the solution, drying and calcining to obtain the catalyst.

4. The method for producing a chromium-based catalyst for dehydrogenation of propane according to claim 3, characterized by: The mass ratio of the total mass of the precursors of Al and Zr to the new fluorocarbon surfactant, the peptizing agent and the pore-expanding agent is 1:(0.005-0.02):(0.12-0.25):(0.04-0.15), and the mass ratio of component B to component A is 1:(0.08-0.5).

5. The method for producing a chromium-based catalyst for dehydrogenation of propane according to claim 4, characterized by: The new fluorocarbon surfactant is perfluoroalkylethoxy ether alcohol or perfluorobutylsulfonyl fluoride; The peptizing agent is any one of a nitric acid solution, a hydrochloric acid solution and an acetic acid solution with a concentration of 5-15 wt%; The pore-expanding agent is at least one of methyl cellulose, urea, hexamethylenetetramine, ammonium acetate and ethylenediamine.

6. The method for producing a chromium-based catalyst for dehydrogenation of propane according to claim 3, characterized by: The processing condition of the microwave plasma generator is processing at a power of 400-600 W for 5-15 min.

7. The method for preparing a chromium-based catalyst for dehydrogenation of propane according to claim 3, characterized by: The temperature of the double-screw extruder is 30-50°C, and the pressure is 1-3.5 MPa, the extrusion die of the double-screw extruder has a hole with a pore diameter of 2.2-3.7 mm, and the length of the extruded strip is 2.5-5 mm.

8. The method for producing a chromium-based catalyst for dehydrogenation of propane according to claim 4, characterized by: The precursor of the modifier is any one of yttrium carbonate, yttrium nitrate, yttrium phosphate and yttrium triflate, or any one of neodymium nitrate, neodymium chloride and neodymium acetylacetonate. The precursor of Al is a mixture of pseudo-boehmite powder and β-alumina powder mixed in any ratio; the precursor of Zr is zirconyl nitrate or zirconium nitrate; The auxiliary precursor is the nitrate corresponding to the auxiliary metal.

9. The method for producing a chromium-based catalyst for dehydrogenation of propane according to claim 3, characterized by: The drying condition is drying at 85-115 ℃ for 8-15 h; The impregnation condition is impregnation at 25-40 ℃ for 2-6 h; The calcination condition is calcination at a temperature rising rate of 1.5-3 ℃ / min to 700-850 ℃ for 4-6 h; The reduction condition is reduction at a temperature rising rate of 0.2-2 ℃ / min to 400-550 ℃ for 4-6 h.

10. A process for the dehydrogenation of propane to propylene, characterized in that: The catalyst is loaded into a fixed bed reactor, hydrogen and propane are introduced, and the reaction is carried out at 570-620 DEG C, 0.05-0.15 MPa; wherein the mass space velocity of propane is 3-6.5 h -1 -1, the molar ratio of hydrogen to propane is 0.05-0.18; and the catalyst is the catalyst of claim 1.