Support for a rapidly decoking alkane dehydrogenation catalyst and its preparation method; the catalyst, its preparation method, and its applications.

Abstract

This invention proposes a method for preparing a support for a rapidly decoking alkane dehydrogenation catalyst, comprising the following steps: a) mixing an alumina precursor, support aid A, support aid B, binder, acid, and water in a mass ratio of 100:0.1-2:0.01-1:0.5-15:0.5-15:10-40 to obtain support precursor A; b) molding, drying, and calcining the support precursor A obtained in step a) to obtain the support; wherein support aid A is selected from one or more soluble salts of Na, K, Mg, Ga, and Zr, and support aid B is an aluminate. This invention also proposes the support obtained by the above preparation method, as well as a catalyst containing the support, its preparation method, and its applications. The support for the rapidly decoking alkane dehydrogenation catalyst provided by this invention incorporates aids, especially aluminates, during the preparation process, which reduces the carbonization temperature and time during the decoking process, significantly reducing decoking energy consumption and broadening the catalyst's application.

Description

Technical Field

[0001] This invention relates to a support for a rapidly decoking alkane dehydrogenation catalyst and its preparation method, a catalyst containing the support, its preparation method, and its application. Background Technology

[0002] Propane dehydrogenation catalysts are prone to carbon buildup and deactivation. Existing research has focused on the speciation and distribution of chromium, and the role of additives in preventing carbon buildup, in order to extend reaction time and improve production efficiency.

[0003] CN107486197B discloses a method for preparing a low-carbon alkane dehydrogenation microsphere catalyst, comprising the following steps: a high-valent chromium precursor is dissolved in a reducing agent solution, then impregnated into an alumina microsphere support; the reaction is carried out at a reaction temperature of 30–200℃ for a reaction time of 0.5–20 h; after washing, filtering, and drying, an additive is impregnated, followed by drying and calcination to obtain the catalyst; the alumina microsphere support comprises 30%–80% macroporous alumina by weight and 20%–70% inorganic oxide binder by weight. The advantages of this invention are that the Cr clusters in the microsphere catalyst are controllable, a catalyst with moderate Cr dispersion is obtained through in-situ reduction, the amount of Brønsted acid on the catalyst surface is reduced, the utilization efficiency of active Cr atoms is improved, and the dehydrogenation activity, selectivity, and anti-carbon deposition performance of the catalyst are enhanced.

[0004] CN107715862B discloses a catalyst for the dehydrogenation of propane to propylene against chromium-deposited carbon, its preparation method, and its application, belonging to the field of chemical catalysis technology. This invention uses rod-shaped alumina rich in unsaturated coordination from ZL201110196192.4 as a support. The surface of this Al2O3 contains a large number of hydroxyl-unsaturated coordinated Al atoms. 3+ This material helps anchor the active component Cr2O3, fostering a strong interaction between Cr2O3 and Al2O3. This prevents Cr2O3 aggregation during the reaction, suppresses side reactions, and inhibits further dehydrogenation and polymerization of propylene to form coke deposits. Consequently, it maintains high propylene selectivity while improving catalyst stability. Therefore, using this Al2O3 support helps improve catalyst selectivity and resistance to deactivation. Compared to other catalysts, this catalyst exhibits high propylene selectivity, slow coke deactivation rate, high stability, and significantly improved mechanical strength, demonstrating promising prospects for industrial applications.

[0005] CN112246236B discloses a chromium-based dehydrogenation catalyst for low-carbon alkane containing a spinel structure and its preparation method. This chromium-based dehydrogenation catalyst is used in a fixed-bed reactor at a reaction pressure of 0.01–1 MPa, a temperature of 530–660 °C, and a mass hourly space velocity of 0.3–8 h⁻¹. -1The low-carbon alkane chromium-based dehydrogenation catalyst comprises the following components by mass fraction based on the total dry weight of the low-carbon alkane chromium-based dehydrogenation catalyst: 0.1–30% chromium oxide, 0.1–10% first promoter, 0.1–10% second promoter, 0.1–10% third promoter, with the balance being a fixed-bed support; the third promoter is one or a mixture of rare earth elements; it possesses good acidity, resulting in higher selectivity for the target product and minimizing acid cracking; it has a stable spinel structure, significantly enhancing the catalyst's strength and stability, and providing a longer service life; its excellent selectivity and stability significantly enhance its resistance to carbon deposition during low-carbon alkane reactions.

[0006] As can be seen from the above, existing technologies focus more on the morphology and distribution of chromium, and the role of additives in resisting carbon deposition, while there is less research on the properties of carbon deposits produced by different catalysts (such as the temperature and time required for decoking). Summary of the Invention

[0007] Based on the above, the purpose of this invention is to provide a support for a rapidly decoking alkane dehydrogenation catalyst and its preparation method, a catalyst containing the support, its preparation method, and its application. The carbon deposits generated in the rapidly decoking alkane dehydrogenation catalyst provided by this invention are easier to burn off (lower temperature and shorter time required for decoking), which can greatly reduce decoking energy consumption and broaden the application of the catalyst.

[0008] Therefore, in a first aspect, the present invention proposes a method for preparing a support for a rapidly decoking alkane dehydrogenation catalyst, comprising the following steps:

[0009] a) Mix alumina precursor, carrier aid A, carrier aid B, binder, acid and water in a mass ratio of 100:0.1-2:0.01-1:0.5-15:0.5-15:10-40, preferably 100:0.5-1:0.1-0.5:1-10:1-10:15-30 to obtain carrier precursor A;

[0010] b) The carrier precursor A obtained in step a) is shaped, dried, and calcined to obtain the carrier;

[0011] The carrier additive A is selected from one or more soluble salts of Na, K, Mg, Ga, and Zr, preferably a soluble salt of sodium; the carrier additive B is an aluminate.

[0012] As a specific embodiment of the present invention, preferably, the alumina precursor is one or more of boehmite, boehmite and aluminum hydroxide, and more preferably boehmite.

[0013] As a specific embodiment of the present invention, preferably, the aluminate is selected from one or more of magnesium aluminate and zinc aluminate, and more preferably magnesium aluminate.

[0014] As a specific embodiment of the present invention, preferably, the adhesive is one or more of guar gum powder, methylcellulose, carbon black, and starch, and more preferably guar gum powder.

[0015] As a specific embodiment of the present invention, preferably, the acid is one or more of nitric acid, oxalic acid, citric acid, and acetic acid, and more preferably nitric acid.

[0016] As a specific embodiment of the present invention, preferably, the molding includes kneading and extrusion; and / or the drying conditions are: temperature 60-200℃, time 8-72h; and / or the calcination conditions are: temperature 400-650℃, time 4-24h.

[0017] As a specific embodiment of the present invention, preferably, the method for preparing the support of the rapidly decoking alkane dehydrogenation catalyst includes the following steps:

[0018] a) Mix alumina precursor, carrier aid A, carrier aid B, binder, acid and water in a mass ratio of 100:0.1-2:0.01-1:0.5-15:0.5-15:10-40, preferably 100:0.5-1:0.1-0.5:1-10:1-10:15-30 to obtain carrier precursor A;

[0019] b) Shape the carrier precursor A obtained in step a) into a shape that is not limited to cylinder, sphere, sheet, or clover shape, to obtain carrier precursor B;

[0020] c) Dry the carrier precursor B described in step b) at 60-200℃ for 8-72 hours to obtain carrier precursor C;

[0021] d) The catalyst precursor C described in c) is calcined at 400-650℃ for 4-24h to obtain the support.

[0022] Therefore, in a second aspect, the present invention provides a support for the catalyst capable of rapid coking prepared by the above-described method, preferably having a specific surface area of ​​110-180 m². 2 / g, preferably 120-160m 2 / g; and / or pore volume of 0.3-0.8cm 3 / g, preferably 0.4-0.7cm 3 / g; and / or loose bulk density of 500-1000 kg / m³ 3 The preferred value is 600-850 kg / m³. 3More preferably, the carrier is cylindrical, spherical, sheet-like, or clover-shaped.

[0023] Therefore, in a third aspect, the present invention proposes a method for preparing a rapidly decoking alkane dehydrogenation catalyst, comprising the following steps:

[0024] 1) The above-mentioned support is used as a catalyst support and is contacted with an aqueous solution of chromium source precursor to obtain catalyst precursor A; the mass ratio of chromium element in the aqueous solution of chromium source precursor to support is 6-15:100, preferably 8-13:100.

[0025] 2) Evaporate, dry and calcine the catalyst precursor A obtained in step 1) to obtain the catalyst.

[0026] As a specific embodiment of the present invention, preferably, the chromium source precursor is a soluble chromium compound; more preferably, the soluble chromium compound is selected from one or more of chromium anhydride, chromium nitrate, and chromium citrate; and even more preferably, chromium nitrate; and / or the evaporation temperature is 60-150°C; and / or the drying conditions are: temperature 100-200°C, time 7-72h; and / or the calcination conditions are: temperature 650-800°C, time 4-24h.

[0027] As a specific embodiment of the present invention, preferably, the preparation method of the rapidly decoking alkane dehydrogenation catalyst includes the following steps:

[0028] 1) Using the aforementioned support as a catalyst support, a chromium source precursor aqueous solution is contacted to obtain catalyst precursor A; the mass ratio of chromium element in the chromium source precursor aqueous solution to the support is 6-15:100, preferably 8-13:100.

[0029] 2) Evaporate the catalyst precursor A described in step 1) to dryness at 60-150℃ to obtain catalyst precursor B;

[0030] 3) Dry the catalyst precursor B described in step 2) at 100-200℃ for 7-72 ​​hours to obtain catalyst precursor C;

[0031] 4) The catalyst precursor C described in step 3) is calcined at 650-800℃ for 4-24h to obtain the catalyst.

[0032] Therefore, in a fourth aspect, the present invention provides a rapidly decoking alkane dehydrogenation catalyst, comprising the support prepared by the above method or the support described above, preferably, the catalyst having a specific surface area of ​​70-110 m². 2 / g, preferably 80-100m 2 / g; and / or pore volume of 0.1-0.5cm 3 / g, preferably 0.2-0.35cm3 / g; and / or loose bulk density of 700-1200 kg / m³ 3 The preferred value is 850-1000 kg / m³. 3 .

[0033] Therefore, in a fifth aspect, the present invention proposes the application of the above-mentioned rapidly decoking alkane dehydrogenation catalyst in the dehydrogenation reaction of low-carbon alkanes, preferably, the low-carbon alkanes are C1-C6 alkanes, and more preferably propane.

[0034] Therefore, in a sixth aspect, the present invention provides a method for dehydrogenating low-carbon alkanes, comprising the following steps: reacting low-carbon alkanes with the above-mentioned alkane dehydrogenation catalyst capable of rapid coking.

[0035] Preferably, the low-carbon alkane is a C1-C6 alkane, and more preferably propane;

[0036] Preferably, the dehydrogenation conditions for the low-carbon alkane include: a temperature of 500-650℃, a pressure of 0.05-0.15 MPa, and a mass hourly space velocity of 0.5-5 h⁻¹. -1 ;

[0037] Preferably, after the reaction has proceeded for 10-240 minutes, when the catalyst is thermally analyzed using a differential scanning calorimeter, and the carrier gas is air with a flow rate of 30 ml / min and a heating rate of 10 °C / min, the peak value of the exothermic peak for coking formation is between 350-500 °C. This indicates that the peak temperature of the exothermic peak for coking formation is relatively low, thus the coking process ends more quickly, achieving rapid coke removal.

[0038] The beneficial effects of this invention are as follows:

[0039] The alkane dehydrogenation catalyst for rapid coking provided by this invention has additives added to its support during the preparation process (conventional catalyst preparation methods involve loading active components and additives onto the support after preparation, such as by impregnation; this invention adds additives during support preparation), especially aluminates. This improves the dispersion and reduces the degree of polymerization of the generated coke, making it easier to oxidize and burn. As a result, the carbonization temperature and time required for the alkane dehydrogenation catalyst to remove coke are reduced, which can greatly reduce the energy consumption for coking and broaden the application of the catalyst. Attached Figure Description

[0040] Figure 1 This is a DSC curve of the alkane dehydrogenation catalyst A1 in Example 1 of the present invention;

[0041] Figure 2 The image shows the DSC curve of the alkane dehydrogenation catalyst D1 of Comparative Example 1 of this invention. Detailed Implementation

[0042] The present invention will be further described below with reference to specific embodiments, but these do not constitute any limitation on the invention. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0043]

[0044]

[0045] Example 1

[0046] Support for preparing alkane dehydrogenation catalyst A1 with rapid coke removal:

[0047] Boehmite, sodium nitrate, magnesium aluminate, guar gum powder, nitric acid, and water were selected and weighed according to a mass ratio of 100:1:0.5:10:10:30. The corresponding masses were then placed in a kneader and kneaded for 30 minutes. After that, the mixture was placed in an extruder and extruded into a cylinder. The cylinder was dried at 60℃ for 72 hours and then calcined at 650℃ for 4 hours to obtain the carrier.

[0048] Preparation of alkane dehydrogenation catalyst A1 with rapid coke removal:

[0049] Chromium nitrate and the prepared support were selected. Chromium nitrate was weighed at a mass ratio of chromium to support of 13:100, dissolved in water and mixed with the support. The mixture was evaporated to dryness at 60℃, dried at 100℃ for 72h, and calcined at 650℃ for 4h to obtain catalyst A1.

[0050] At a temperature of 600℃, a pressure of 0.1MPa, and a mass hourly space velocity of 1h... -1 Under the given conditions, the obtained catalyst A1 was reacted with propane for 4 hours to obtain conversion 1 and selectivity 1 data.

[0051] At a temperature of 600℃, a pressure of 0.1MPa, and a mass hourly space velocity of 1h... -1 Under the conditions of contacting the reacted catalyst A1 with air for 30 min, the reaction was carried out at a temperature of 600℃, a pressure of 0.1 MPa, and a mass hourly space velocity of 1 h⁻¹. -1 Under the given conditions, catalyst A1 was reacted with propane for 4 hours to obtain conversion 2 and selectivity 2 data.

[0052] The DSC experiment was performed on a TA Instruments DSC250 differential scanning calorimeter. 60 mg of sample was weighed, heated to 1000 °C at a rate of 10 °C / min, and air was used as the carrier gas.

[0053] The active component A and its ratio to the alumina precursor, the active component B and its ratio to the alumina precursor, the chromium content and its ratio to the support, conversion rate 1, selectivity 1, conversion rate 2, selectivity 2, and the peak value of the DSC exothermic peak of the catalyst A1 are shown in Table 1. The DSC curves are shown in Table 1. Figure 1 .

[0054] The specific surface area of ​​carrier A1 is 134 m². 2 / g, pore volume 0.56cm 3 / g, loose bulk density is 730kg / m³ 3 .

[0055] Catalyst A1 has a specific surface area of ​​94 m². 2 / g, pore volume is 0.33cm 3 / g, loose bulk density is 960kg / m³ 3 .

[0056] Example 2

[0057] Support for preparing alkane dehydrogenation catalyst A2 with rapid coke removal:

[0058] Boehmite, potassium nitrate, magnesium aluminate, methylcellulose, oxalic acid, and water were selected and weighed according to a mass ratio of 100:0.5:0.1:1:1:15. The corresponding masses were then placed in a kneader and kneaded for 30 minutes. After that, the mixture was placed in an extruder and extruded into a cylinder. The cylinder was dried at 200℃ for 8 hours and then calcined at 650℃ for 24 hours to obtain the carrier.

[0059] Preparation of alkane dehydrogenation catalyst A2 with rapid coke removal:

[0060] Chromium anhydride and the prepared support were selected. Chromium nitrate was weighed at a mass ratio of chromium to support of 8:100, dissolved in water and mixed with the support. The mixture was evaporated to dryness at 150℃, dried at 100℃ for 72h, and calcined at 650℃ for 4h to obtain catalyst A2.

[0061] At a temperature of 600℃, a pressure of 0.1MPa, and a mass hourly space velocity of 1h... -1 Under the given conditions, the obtained catalyst A2 was reacted with propane for 4 hours to obtain conversion 1 and selectivity 1 data.

[0062] At a temperature of 600℃, a pressure of 0.1MPa, and a mass hourly space velocity of 1h... -1 Under the conditions of contacting the reacted catalyst A2 with air for 30 min, the mixture was then subjected to further treatment at a temperature of 600 °C, a pressure of 0.1 MPa, and a mass hourly space velocity of 1 h⁻¹. -1 Under the given conditions, catalyst A2 was reacted with propane for 4 hours to obtain conversion 2 and selectivity 2 data.

[0063] The active component A of catalyst A2 and its ratio to the alumina precursor, active component B and its ratio to the alumina precursor, chromium content and its ratio to the support, conversion rate 1, selectivity 1, conversion rate 2, selectivity 2, and DSC exothermic peak value are shown in Table 1.

[0064] Example 3

[0065] Support for the preparation of alkane dehydrogenation catalyst A3 with rapid coke removal:

[0066] Phobosite, zirconium nitrate, zinc aluminate, carbon black, citric acid, and water were selected and weighed according to a mass ratio of 100:2:1:15:15:40. The mixture was then kneaded in a kneader for 30 minutes, extruded into cylinders using an extruder, dried at 200℃ for 72 hours, and calcined at 400℃ for 24 hours to obtain the carrier.

[0067] Preparation of alkane dehydrogenation catalyst A3 with rapid coke removal:

[0068] Chromium citrate and the prepared support were selected. Chromium nitrate was weighed at a mass ratio of chromium to support of 15:100, dissolved in water and mixed with the support. The mixture was evaporated to dryness at 150℃, dried at 100℃ for 72h, and calcined at 650℃ for 4h to obtain catalyst A3.

[0069] At a temperature of 600℃, a pressure of 0.1MPa, and a mass hourly space velocity of 1h... -1 Under the given conditions, the obtained catalyst A3 was reacted with propane for 4 hours to obtain conversion 1 and selectivity 1 data.

[0070] At a temperature of 600℃, a pressure of 0.1MPa, and a mass hourly space velocity of 1h... -1 Under the conditions of contacting the reacted catalyst A3 with air for 30 min, the reaction was carried out at a temperature of 600℃, a pressure of 0.1 MPa, and a mass hourly space velocity of 1 h⁻¹. -1 Under the given conditions, catalyst A3 was reacted with propane for 4 hours to obtain conversion 2 and selectivity 2 data.

[0071] The active component A of catalyst A3 and its ratio to alumina precursor, active component B and its ratio to alumina precursor, chromium content and its ratio to support, conversion rate 1, selectivity 1, conversion rate 2, selectivity 2, and DSC exothermic peak value are shown in Table 1.

[0072] Example 4

[0073] Support for preparing alkane dehydrogenation catalyst A4 with rapid coke removal:

[0074] Aluminum hydroxide, magnesium nitrate, zinc aluminate, starch, acetic acid, and water were selected and weighed according to a mass ratio of 100:0.1:0.01:0.5:0.5:10. The corresponding masses were then placed in a kneader and kneaded for 30 minutes. After that, the mixture was placed in an extruder and extruded into a cylinder. The cylinder was dried at 60°C for 8 hours and then calcined at 400°C for 4 hours to obtain the carrier.

[0075] Preparation of alkane dehydrogenation catalyst A4 with rapid coke removal:

[0076] Chromium anhydride and the prepared support were selected. Chromium nitrate was weighed at a mass ratio of chromium to support of 6:100, dissolved in water and mixed with the support. The mixture was evaporated to dryness at 150℃, dried at 100℃ for 72h, and calcined at 650℃ for 4h to obtain catalyst A4.

[0077] At a temperature of 600℃, a pressure of 0.1MPa, and a mass hourly space velocity of 1h... -1 Under the given conditions, the obtained catalyst A4 was reacted with propane for 4 hours to obtain conversion 1 and selectivity 1 data.

[0078] At a temperature of 600℃, a pressure of 0.1MPa, and a mass hourly space velocity of 1h... -1 Under the conditions of contacting the reacted catalyst A4 with air for 30 min, the reaction was carried out at a temperature of 600℃, a pressure of 0.1 MPa, and a mass hourly space velocity of 1 h⁻¹. -1 Under the given conditions, catalyst A4 was reacted with propane for 4 hours to obtain conversion 2 and selectivity 2 data.

[0079] The active component A of catalyst A4 and its ratio to the alumina precursor, active component B and its ratio to the alumina precursor, chromium content and its ratio to the support, conversion rate 1, selectivity 1, conversion rate 2, selectivity 2, and DSC exothermic peak value are shown in Table 1.

[0080] Comparative Example 1

[0081] Support for the preparation of alkane dehydrogenation catalyst D1 with rapid coke removal:

[0082] Select boehmite and water, weigh them according to a mass ratio of 100:30, put them into a kneader and knead for 30 minutes, then put them into an extruder and extrude them into cylinders. Dry them at 60℃ for 72 hours and then calcine them at 650℃ for 4 hours to obtain the carrier.

[0083] Preparation of alkane dehydrogenation catalyst D1 with rapid coke removal:

[0084] Chromium nitrate and the prepared support were selected. Chromium nitrate was weighed at a mass ratio of chromium to support of 13:100, dissolved in water and mixed with the support. The mixture was evaporated to dryness at 60℃, dried at 100℃ for 72h, and calcined at 650℃ for 4h to obtain catalyst D1.

[0085] At a temperature of 600℃, a pressure of 0.1MPa, and a mass hourly space velocity of 1h... -1 Under the given conditions, the obtained catalyst D1 was reacted with propane for 4 hours to obtain conversion 1 and selectivity 1 data.

[0086] At a temperature of 600℃, a pressure of 0.1MPa, and a mass hourly space velocity of 1h... -1 Under the conditions of contacting the reacted catalyst A1 with air for 30 min, the reaction was carried out at a temperature of 600℃, a pressure of 0.1 MPa, and a mass hourly space velocity of 1 h⁻¹. -1 Under the given conditions, catalyst D1 was reacted with propane for 4 hours to obtain conversion 2 and selectivity 2 data.

[0087] The DSC experiment was performed on a TA Instruments DSC250 differential scanning calorimeter. 60 mg of sample was weighed, heated to 1000 °C at a rate of 10 °C / min, and air was used as the carrier gas.

[0088] The active component A and its ratio to the alumina precursor, the active component B and its ratio to the alumina precursor, the chromium content and its ratio to the support, conversion rate 1, selectivity 1, conversion rate 2, selectivity 2, and the peak value of the DSC exothermic peak of catalyst D1 are shown in Table 1. The DSC curves are shown in Table 1. Figure 2 .

[0089] The specific surface area of ​​the carrier is 210 m². 2 / g, pore volume is 0.23cm 3 / g, loose bulk density is 430kg / m³ 3 .

[0090] The specific surface area of ​​catalyst D1 is 130 m². 2 / g, pore volume 0.07cm 3 / g, loose bulk density is 620kg / m³ 3 .

[0091] Comparative Example 2

[0092] The catalyst was prepared according to the method of Example 1, except that no auxiliary agent A was added, resulting in catalyst D2.

[0093] At a temperature of 600℃, a pressure of 0.1MPa, and a mass hourly space velocity of 1h... -1 Under the given conditions, the obtained catalyst D2 was reacted with propane for 4 hours to obtain conversion 1 and selectivity 1 data.

[0094] At a temperature of 600℃, a pressure of 0.1MPa, and a mass hourly space velocity of 1h... -1 Under these conditions, the reacted catalyst D2 was contacted with air for 30 min, and then subjected to further treatment at a temperature of 600℃, a pressure of 0.1 MPa, and a mass hourly space velocity of 1 h⁻¹.-1 Under the given conditions, catalyst D2 was reacted with propane for 4 hours to obtain conversion 2 and selectivity 2 data.

[0095] The DSC experiment was performed on a TA Instruments DSC250 differential scanning calorimeter. 60 mg of sample was weighed, heated to 1000 °C at a rate of 10 °C / min, and air was used as the carrier gas.

[0096] The active component A and its ratio to the alumina precursor, the active component B and its ratio to the alumina precursor, the chromium content and its ratio to the support, conversion rate 1, selectivity 1, conversion rate 2, selectivity 2, and the peak value of the DSC exothermic peak of the catalyst D2 are shown in Table 1.

[0097] Comparative Example 3

[0098] The catalyst was prepared according to the method in Example 1, except that the promoter B was not added, resulting in catalyst D3.

[0099] At a temperature of 600℃, a pressure of 0.1MPa, and a mass hourly space velocity of 1h... -1 Under the given conditions, the obtained catalyst D3 was reacted with propane for 4 hours to obtain conversion 1 and selectivity 1 data.

[0100] At a temperature of 600℃, a pressure of 0.1MPa, and a mass hourly space velocity of 1h... -1 Under the conditions of contacting the reacted catalyst D3 with air for 30 min, the mixture was then subjected to further treatment at a temperature of 600 °C, a pressure of 0.1 MPa, and a mass hourly space velocity of 1 h⁻¹. -1 Under the given conditions, catalyst D3 was reacted with propane for 4 hours to obtain conversion 2 and selectivity 2 data.

[0101] The DSC experiment was performed on a TA Instruments DSC250 differential scanning calorimeter. 60 mg of sample was weighed, heated to 1000 °C at a rate of 10 °C / min, and air was used as the carrier gas.

[0102] The active component A and its ratio to the alumina precursor, the active component B and its ratio to the alumina precursor, the chromium content and its ratio to the support, conversion rate 1, selectivity 1, conversion rate 2, selectivity 2, and the peak value of the DSC exothermic peak of the catalyst D3 are shown in Table 1.

[0103] Comparative Example 4

[0104] The catalyst was prepared according to the method of Example 1, except that additives A and B were not added during the preparation of the support, but were added during the impregnation of the support, resulting in catalyst D4.

[0105] At a temperature of 600℃, a pressure of 0.1MPa, and a mass hourly space velocity of 1h... -1Under the given conditions, the obtained catalyst D4 was reacted with propane for 4 hours to obtain conversion 1 and selectivity 1 data.

[0106] At a temperature of 600℃, a pressure of 0.1MPa, and a mass hourly space velocity of 1h... -1 Under these conditions, the reacted catalyst D4 was contacted with air for 30 min, and then subjected to a reaction at 600 °C, a pressure of 0.1 MPa, and a mass hourly space velocity of 1 h⁻¹. -1 Under the given conditions, catalyst D4 was reacted with propane for 4 hours to obtain conversion 2 and selectivity 2 data.

[0107] The DSC experiment was performed on a TA Instruments DSC250 differential scanning calorimeter. 60 mg of sample was weighed, heated to 1000 °C at a rate of 10 °C / min, and air was used as the carrier gas.

[0108] The active component A and its ratio to the alumina precursor, the active component B and its ratio to the alumina precursor, the chromium content and its ratio to the support, conversion rate 1, selectivity 1, conversion rate 2, selectivity 2, and the peak value of the DSC exothermic peak of the catalyst D4 are shown in Table 1.

[0109] Table 1

[0110]

[0111] As can be seen from the comparison between Example 1 and Comparative Examples 1-4, the conversion rates 1 and 2 of the alkane dehydrogenation catalyst provided in Example 1 are close, and the selectivity 1 and selectivity 2 are close. The conversion rate 2 and selectivity 2 are basically not reduced, indicating that the coke removal has been completed under the action of air for 30 minutes. In Comparative Examples 1-4, the conversion rate 2 and selectivity 2 decreased significantly, indicating that the coke removal was not completed under the action of air for 30 minutes and the activity could not be restored.

[0112] As shown in Table 1, the peak temperature of the DSC exothermic peak of the alkane dehydrogenation catalysts provided in Examples 1-4 is greatly reduced, indicating that the carbon deposits generated on the surface of the alkane dehydrogenation catalyst are easier to remove in the alkane dehydrogenation reaction, thus shortening the coking time and achieving the purpose of rapid coking removal, which can greatly reduce the energy consumption of coking removal.

[0113] In summary, the alkane dehydrogenation catalyst for rapid coking provided in the embodiments of the present invention has additives, especially aluminates, added in advance during the preparation process. This reduces the carbonization temperature and time when the alkane dehydrogenation catalyst removes carbon deposits, which can greatly reduce the energy consumption for coking removal and make the catalyst more widely applicable.

[0114] Any numerical value mentioned in this invention, if there is only a two-unit interval between any minimum and any maximum value, includes all values ​​that increase by one unit each time from the minimum to the maximum value. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, or time, is stated as 50-90, in this specification it means specifically listing values ​​such as 51-89, 52-88… and 69-71 and 70-71, etc. For non-integer values, it may be appropriately considered that a unit is 0.1, 0.01, 0.001, or 0.0001. These are merely some specifically specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0115] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for preparing a support for a rapidly decoking alkane dehydrogenation catalyst, characterized in that, Includes the following steps: a) Mix alumina precursor, carrier aid A, carrier aid B, binder, acid and water in a mass ratio of 100 : 0.1-2 : 0.01-1 : 0.5-15 : 0.5-15 : 10-40 to obtain carrier precursor A; b) The carrier precursor A obtained in step a) is shaped, dried, and calcined to obtain the carrier; Wherein, the carrier additive A is selected from one or more soluble salts of Na, K, Mg, Ga, and Zr; the carrier additive B is an aluminate, which is selected from one or more magnesium aluminate and zinc aluminate.

2. The preparation method according to claim 1, characterized in that, Mix the alumina precursor, carrier aid A, carrier aid B, binder, acid and water in a mass ratio of 100 : 0.5-1 : 0.1-0.5 : 1-10 : 1-10 : 15-30.

3. The preparation method according to claim 1, characterized in that, The carrier additive A is a sodium-soluble salt.

4. The preparation method according to claim 1, characterized in that, The alumina precursor is one or more of boehmite, boehmite and aluminum hydroxide.

5. The preparation method according to claim 4, characterized in that, The alumina precursor is boehmite.

6. The preparation method according to any one of claims 1-5, characterized in that, The aluminate is magnesium aluminate; And / or, the adhesive is one or more of guar gum powder, methylcellulose, carbon black, and starch; And / or, the acid is one or more of nitric acid, oxalic acid, citric acid, and acetic acid.

7. The preparation method according to claim 6, characterized in that, The adhesive is guar gum powder.

8. The preparation method according to claim 6, characterized in that, The acid is nitric acid.

9. The preparation method according to any one of claims 1-5, characterized in that, The forming process includes kneading and extrusion; and / or the drying conditions are: temperature 60-200℃, time 8-72h; and / or the calcination conditions are: temperature 400-650℃, time 4-24h.

10. A support for a catalyst capable of rapid coking prepared by the preparation method according to any one of claims 1-9.

11. The carrier according to claim 10, characterized in that, The specific surface area of ​​the carrier is 110-180 m². 2 / g; and / or pore volume of 0.3-0.8cm 3 / g; and / or loose bulk density of 500-1000 kg / m³ 3 .

12. The carrier according to claim 11, characterized in that, The specific surface area of ​​the carrier is 120-160 m². 2 / g; and / or pore volume of 0.4-0.7cm 3 / g; and / or loose bulk density of 600-850 kg / m³ 3 .

13. The carrier according to any one of claims 10-12, characterized in that, The carrier can be cylindrical, spherical, sheet-like, or clover-shaped.

14. A method for preparing a rapidly decoking alkane dehydrogenation catalyst, characterized in that, Includes the following steps: 1) The support according to any one of claims 10-13 is contacted with an aqueous solution of a chromium source precursor to obtain catalyst precursor A; the mass ratio of chromium element in the aqueous solution of the chromium source precursor to the support is 6-15:100; 2) Evaporate, dry and calcine the catalyst precursor A obtained in step 1) to obtain the catalyst.

15. The preparation method according to claim 14, characterized in that, The mass ratio of chromium to carrier in the aqueous solution of the chromium source precursor is 8-13:

100.

16. The preparation method according to claim 14, characterized in that, The chromium source precursor is a soluble chromium compound; and / or the evaporation temperature is 60-150℃; and / or the drying conditions are: temperature 100-200℃, time 7-72h; and / or the calcination conditions are: temperature 650-800℃, time 4-24h.

17. The preparation method according to claim 16, characterized in that, The soluble chromium compound is selected from one or more of chromium anhydride, chromium nitrate, and chromium citrate.

18. The preparation method according to claim 17, characterized in that, The soluble chromium compound is chromium nitrate.

19. An alkane dehydrogenation catalyst capable of rapid coking, characterized in that, The carrier comprises the carrier prepared by the method of any one of claims 1-9 or the carrier of any one of claims 10-13.

20. The alkane dehydrogenation catalyst according to claim 19, characterized in that, The catalyst has a specific surface area of ​​70-110 m². 2 / g; and / or pore volume of 0.1-0.5cm 3 / g; and / or loose bulk density of 700-1200 kg / m³ 3 .

21. The alkane dehydrogenation catalyst according to claim 20, characterized in that, The catalyst has a specific surface area of ​​80-100 m². 2 / g; and / or pore volume of 0.2-0.35cm³ 3 / g; and / or loose bulk density of 850-1000 kg / m³ 3 .

22. The application of the alkane dehydrogenation catalyst capable of rapid coking as described in any one of claims 19-21 in the dehydrogenation reaction of low-carbon alkanes.

23. The application according to claim 22, characterized in that, The low-carbon alkanes are C1-C6 alkanes.

24. The application according to claim 23, characterized in that, The low-carbon alkane is propane.

25. A method for dehydrogenating low-carbon alkanes, characterized in that, Includes the following steps: The low-carbon alkanes are reacted with the alkane dehydrogenation catalyst capable of rapid coking as described in any one of claims 19-21.

26. The method according to claim 25, characterized in that, The low-carbon alkanes are C1-C6 alkanes.

27. The method according to claim 26, characterized in that, The low-carbon alkane is propane.

28. The method according to claim 25, characterized in that, The dehydrogenation conditions for the low-carbon alkanes include: a temperature of 500-650℃, a pressure of 0.05-0.15 MPa, and a mass hourly space velocity (HSV) of 0.5-5 h⁻¹. -1 .

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