A thermal auxiliary material for promoting the dehydrogenation reaction efficiency of alkanes, its preparation method and application

Abstract

The present invention belongs to the technical field of petrochemical industry, and specifically relates to a thermal auxiliary material for promoting the dehydrogenation reaction efficiency of alkanes, its preparation method and application. The auxiliary material is composed of a heat-generating main body, a heat storage carrier, a stabilizing auxiliary agent, and a carrier auxiliary agent; among them: the heat-generating main body component is CuO; the heat storage carrier component is a CaO-Al2O3 composite oxide; the stabilizing auxiliary agent is one or more of Cr2O3, La2O3, CeO2, and ZrO2; the carrier auxiliary agent is one or more of MgO, BaO, NiO, and Fe2O3. The present invention synthesizes a thermal auxiliary material with high mechanical strength, high heat transfer performance, and high stability through steps such as coprecipitation reaction, high-temperature hydrothermal reaction, high-temperature calcination, vacuum impregnation, and ultrasonic oscillation; when this material is applied to an alkane dehydrogenation to olefin device, it is beneficial to improve the alkane conversion rate and olefin selectivity, extend the catalyst operation life, reduce the device energy consumption, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of petrochemical industry, and particularly relates to a thermal auxiliary material for promoting the reaction efficiency of alkane dehydrogenation (to produce olefins), a preparation method thereof, and an application thereof. Background Art

[0002] The technology of producing olefins by alkane dehydrogenation has been industrialized since the 1930s of the 20th century. However, the routes mainly rely on steam cracking and catalytic cracking by-products of naphtha, light fuel oil, etc. to produce olefins. This not only has high energy consumption but also low output, and can no longer meet the contemporary society's demand for low-carbon olefins. In recent years, low-carbon olefins mainly including ethylene, propylene, butene, etc. have become the cornerstone of the development of the modern chemical industry. At the same time, the technology of producing olefins by dehydrogenation of low-carbon alkanes, which has been booming, has increasingly become an important way for olefin production.

[0003] Among them, ethylene, as the organic chemical raw material with the highest global output, is known as the "mother of the petrochemical industry" and is an important organic material connecting the upstream and downstream industries of the petrochemical industry. In recent years, with the large-scale exploitation of shale gas resources in North America, the technology of producing ethylene by dehydrogenation of by-product light ethane has also attracted much attention. However, at present, most of these emerging processes or reaction processes are in the laboratory stage, and industrial production is relatively immature. Propylene, as one of the basic raw materials second only to ethylene in the chemical industry, is widely used in the production of polypropylene, acrylic acid, acrylonitrile, butanol, octanol, propylene oxide, isopropanol and other products. The direct dehydrogenation of propane to propylene has become an important way for propylene production at present because of its relatively mature technology and lower comprehensive cost. Butene, as a key raw material for chemical products such as synthetic rubber, plastics, solvents, pharmaceuticals, and high-octane gasoline, has a steadily growing market demand. The technology of directly dehydrogenating butane to butene is highly mature and has low production cost, and is widely used in the petrochemical industry. In recent years, the large-scale rise of mixed alkane dehydrogenation devices also represents the future development direction of alkane dehydrogenation technology.

[0004] At present, the main technologies for realizing the industrial application of low-carbon alkane dehydrogenation are the Catofin fixed-bed process of Lummus Technology Company and the Oleflex moving-bed process of UOP in the United States. Compared with the Oleflex process, the Catofin process has received increasing attention from domestic research scholars because it uses a cheap chromium-based catalyst and has higher operating economy and operation adaptability. However, this process has the inherent characteristic of strong endothermicity in the alkane dehydrogenation reaction under the intermittent operation mode of the fixed-bed reactor, which causes the bed temperature to drop rapidly and shows an extremely uneven temperature distribution. In recent years, the introduction of a new material HGM (Heat Generation Material) in the Catofin fixed-bed process has effectively improved the temperature distribution of the catalyst bed, and has a positive promoting effect on improving product yield, reducing energy consumption, increasing economic benefits, and reducing device investment.

[0005] This new type of heating material is a functional metal oxide material with oxidation and reduction properties. It has no catalytic activity for propane dehydrogenation reaction and will not cause other side reactions. This material can release a large amount of heat during the reduction reaction in the alkane dehydrogenation process and also release a large amount of heat during the air regeneration process. The principle is as follows:

[0006] Reduction reaction: MeO + H 2 (g) → Me + H 2 O(g) + Heat release

[0007] Oxidation reaction: Me + 0.5O 2 (g) → MeO + Heat release

[0008] where Me is the active metal

[0009] Generally, the heat source of the catalyst bed layer in the dehydrogenation reactor comes from the hot air at the top of the catalyst bed layer and the heat released by injection combustion. Due to the uneven distribution of the gas flow, the temperature distribution and heat storage of the bed layer are extremely uneven. Coking will occur when the local area is overheated, blocking the bed layer; while the catalytic efficiency will decrease significantly when the local area is overcooled. The heating material can be selectively added to any position in the bed layer that requires heat. In this way, during the air regeneration stage, the material releases a large amount of heat during oxidation, which can partially replace the heat from hot air or injection combustion, reducing the energy consumption of the device; during the catalyst reduction stage, it can further release heat to increase the bed layer temperature; overall, it realizes the temperature compensation of the catalyst bed layer in this part, thereby improving the conversion rate and selectivity of propane dehydrogenation.

[0010] Chinese Patent CN106029612A first disclosed an improved dehydrogenation process using a heating material. The heating material carrier includes: alumina, aluminum hydroxide, trihydroxyaluminum, boehmite, boehmite-like, gibbsite, α-alumina, aluminate, calcium aluminate, zeolite, chromium oxide, magnesium oxide, etc. The metal oxides of the heating components include: copper, chromium, molybdenum, vanadium, cerium, yttrium, etc. and their combinations. The oxide content accounts for 2.0 wt.% - 40 wt.% of the total weight of the heating material. In particular, taking copper oxide as the heating component, it accounts for 3.0 wt.% - 20.0 wt.% of the total weight of the heating material. In terms of heating performance, during the reduction treatment process, it can increase the temperature of the propane dehydrogenation to propylene catalyst by ≥5°C. The mixing volume ratio of the heating material as an inert component to the catalyst is in the range of 3:1 - 1:3.

[0011] Chinese Patent CN108176405B discloses an alkane dehydrogenation reaction enhancing additive, in which the CaO content is 15 wt% - 18 wt%, Al 2 O 3Oxides or mixtures thereof selected from Group VIII, Group VI, Group IA, Group IIA and rare earth elements with a content of 70 wt% to 80 wt%, a CuO content of 6 wt% to 15 wt% and 0.01 wt% to 3 wt%; the aluminum compound and the calcium compound are directly mixed and calcined at a high temperature of 800 to 1400 °C for 0.5 to 15 hours, and then impregnated with a Cu solution.

[0012] Chinese Patent CN108300430B discloses an exothermic promoter for the alkane dehydrogenation reaction process, its preparation method and its use method. Its composition is 10 - 35 wt% of CaO, 50 - 85 wt% of Al 2 O 3 , 5 - 30 wt% of CuO, and 0 - 3 wt% of metal oxides selected from Group VIII, Group IIB, Group IIIB, and Group VIIB. The aluminum compound, calcium compound, and solid copper compound are mixed and formed, and then placed in a high-temperature roasting at 800 - 1400 °C for 0.2 - 24 hours.

[0013] Chinese Patent CN113388376B discloses an alkane dehydrogenation exothermic promoter, its preparation method and its application, which are mainly prepared from CaO, CuO and Al 2 O 3 . In this alkane dehydrogenation exothermic promoter, the Cu element mainly exists in the forms of CaCu 2 O 3 and Ca 2 CuO 3 . There is no free alumina phase. It is reported that the reaction between CuO and alumina to produce copper aluminate spinel can be avoided; with calcium aluminate as the skeleton, the ratio of the number of Ca atoms to the number of Al atoms ≥ 6 / 7. It is reported that the adhesion phenomenon caused by the sintering of the carrier under certain conditions can be avoided.

[0014] Chinese Patent CN117427669A discloses a preparation method of a low-carbon alkane dehydrogenation reaction promoter. This promoter is composed of elements Ca, Cu, Ce, V, P, Si, and Al. Calculated by the mass percentage of oxides, CaO is 5 - 28%, CuO is 2 - 22%, CeO 2 is 0.8 - 3.3%, V 2 O 3 is 1 - 4.7%, P 2 O 5 is 0.5 - 2.7%, SiO 2 is 5 - 12%, and the rest is Al 2 O 3 ; Al 2 O 3 is α - Al 2 O 3, After roasting and sulfur loading treatment, the pipeline can be passivated and the initial activity of the dehydrogenating agent can be eliminated, improving the yield of the dehydrogenation reaction.

[0015] Chinese Patent CN112812752B discloses a heat storage material for propane catalytic dehydrogenation to propylene with a specific pore structure and its preparation method. The heat storage material is a Cu-based material supported on Al 2 O 3 By adding a pore-forming agent, the pore structure of the Al 2 O 3 carrier material is adjusted and formed, further improving the propane conversion rate and propylene selectivity, and releasing heat during the reduction stage and the air regeneration stage, making the bed temperature distribution more uniform.

[0016] Basically, the preparation of the heat-generating / heat-releasing / heat-storing materials / auxiliaries mentioned in the above patents is made with aluminum compounds, calcium compounds and copper compounds as the main components, and the preparation route is basically the method of physical mixing and then calcination. The differences lie in the different ways and types of adding auxiliaries. Some are to avoid the combination of heat-generating components and the carrier, some are to increase the pore structure of the carrier, and some are to eliminate the initial activity of the dehydrogenation catalyst, etc. However, none of them involve the method of promoting the overall structural stability of the heat-generating material, improving the mechanical strength, and enhancing the heat-releasing, heat-transferring and heat-absorbing capabilities. During the low-carbon alkane dehydrogenation reaction process, the heat-generating material not only needs to continuously absorb / release heat by itself, but also faces the cycle of high-temperature process conditions and the thermal shock of gas or steam. After long-term operation, sintering and pulverization are likely to occur, resulting in the inactivation of the dehydrogenation catalyst or the reduction of its service life. If the carrier structure is unstable, the deep combination of the heat-releasing component and the carrier is likely to occur; if the pore structure is too rich, the overall strength of the material will be reduced; if the active components are not evenly dispersed, it will also lead to the accumulation and sintering of the active components, and the overall heat-transferring and heat-releasing capabilities will decline. Therefore, it is necessary to propose a method for improving the stability of the carrier structure and the heat-generating components of the heat-generating material. Summary of the Invention

[0017] Aiming at the deficiencies of the prior art, one of the objectives of the present invention is to provide a high-strength thermal auxiliary material for improving the efficiency of alkane dehydrogenation reaction. Its heat-generating main component is CuO, and its heat storage main component is CaO-Al 2 O 3 composite oxide, and a stabilizing auxiliary and a carrier auxiliary are added. This auxiliary material has high mechanical strength, good wear resistance, high hydrothermal stability, stable heat-releasing, heat-storing and heat-transferring capabilities, has no obvious catalytic effect in the alkane dehydrogenation reaction, can effectively assist the alkane dehydrogenation catalyst, improve its conversion rate and selectivity, extend the service life of the catalyst, and reduce the energy consumption of the device.

[0018] Another objective of the present invention is to provide a preparation method of the above thermal auxiliary material.

[0019] To achieve the above invention objectives, the specific technical solution of the present invention is as follows:

[0020] A thermal auxiliary material for promoting the dehydrogenation reaction efficiency of alkanes, comprising a heat-generating main body, a heat storage carrier, a stabilizing auxiliary agent, and a carrier auxiliary agent; wherein: the component of the heat-generating main body is CuO; the component of the heat storage carrier is CaO-Al 2 O 3 composite oxide; calculated as oxides, the mass percentages of each component in the auxiliary material are: 4 wt.% to 15 wt.% of CuO, 10 wt.% to 20 wt.% of CaO, 65 wt.% to 80 wt.% of Al 2 O 3 , 0 wt.% to 3 wt.% of the stabilizing auxiliary agent and 0 wt.% to 3 wt.% of the carrier auxiliary agent, and the sum of the total mass percentages is 100%.

[0021] Further, the carrier auxiliary agent is one or more of MgO, BaO, NiO, Fe 2 O 3 .

[0022] Further, the stabilizing auxiliary agent is one or more of Cr 2 O 3 , La 2 O 3 , CeO 2 , ZrO 2 .

[0023] As a preferred embodiment of the present invention, the preparation method of the above-mentioned thermal auxiliary material includes the following steps:

[0024] Mix the aluminum compound, calcium compound, and carrier auxiliary agent salt for preparing the heat storage carrier through one-step or two-step coprecipitation reaction, and uniformly mix them in the form of carbonate or basic salt or basic carbonate partially or completely, then form a structurally stable carrier precursor through high-temperature hydrothermal reaction, and then form a structurally dense heat storage carrier through high-temperature calcination, and finally load the heat-generating component and the stabilizing auxiliary agent on the heat storage carrier.

[0025] More specifically, the above preparation method includes the following specific steps:

[0026] (1) First, mix the aluminum compound, calcium compound, carrier auxiliary agent salt with deionized water to prepare a mixed solution, then add an alkaline precipitant through one-step or two-step coprecipitation, control the pH value at 6.5 to 12.0 (specifically, it can be 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, etc.) to obtain a mixed precipitate; and perform aging;

[0027] (2) The aged material in step (1) is filtered, washed, pulped or wet-milled, and then poured into a high-pressure hydrothermal stirring reactor. Set the stirring rate at 80 - 300 revolutions per minute, heat up to 120 - 250 °C, and carry out hydrothermal reaction for 2 - 24 hours in a closed state. Filter the reaction material again, and dry it at 80 °C - 200 °C to obtain the precursor powder;

[0028] (3) Add 10 - 20% of water by weight of the dried precursor powder in step (2) for kneading, and add a binder for extrusion molding or rolling ball molding, or add a demolding agent for tableting;

[0029] (4) Dry and calcine the formed material in step (3);

[0030] (5) Immerse the calcined formed material in step (4) in a copper salt and stabilizing additive salt solution in a vacuum environment, and then oscillate it in an ultrasonic device;

[0031] (6) Dry the sample impregnated in step (5) at 100 - 200 °C for 2 - 12 hours, and then calcine it at 400 - 900 °C for 2 - 10 hours to obtain the finished product of the thermal auxiliary material.

[0032] Further, in step (1):

[0033] The aluminum compound is one or more of aluminum nitrate, aluminum sulfate, aluminum chloride, aluminum isopropoxide, basic aluminum carbonate, sodium metaaluminate, aluminum hydroxide, gibbsite, bayerite, nordstrandite, boehmite, pseudoboehmite, and various aluminum oxide hydrates, preferably one or more of aluminum nitrate, aluminum sulfate, aluminum chloride, and aluminum isopropoxide;

[0034] The calcium compound is one or more of calcium nitrate, calcium chloride, calcium bicarbonate, calcium gluconate, calcium hydrogen malate, calcium sulfate, calcium hydroxide, and calcium carbonate, preferably one or more of calcium nitrate, calcium chloride, and calcium bicarbonate;

[0035] The carrier additive salt is one or more of magnesium nitrate, barium nitrate, nickel nitrate, and iron nitrate, preferably magnesium nitrate;

[0036] The basic precipitating agent is one or more of sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium hydroxide, potassium carbonate, and ammonia water, preferably one or two of sodium carbonate and sodium hydroxide.

[0037] The aging temperature is 60 - 95 °C, and the time is 2 - 10 hours.

[0038] Further, in step (2):

[0039] The washing step usually uses hot water at room temperature - 80 °C for washing, and the number of washing times is 2 - 4 times;

[0040] In the beating or wet grinding step, a beater or a wet ball mill is generally used to further uniformly mix the washed materials, and the mixing time is 1 to 3 hours.

[0041] Further, in the step (3):

[0042] The binder is one or more of carboxymethyl cellulose, sesbania powder, polyvinyl alcohol, aluminum sol, and pseudo-boehmite;

[0043] The addition amount of the binder is 0 to 2% of the weight of the precursor powder, preferably 0 to 0.5%;

[0044] The release agent is one or more of graphite, magnesium stearate, aluminum stearate, and calcium stearate, and preferably calcium stearate;

[0045] The addition amount of the release agent is 0 to 1% of the weight of the precursor powder, preferably 0 to 0.5%.

[0046] Further, in the step (4):

[0047] The drying temperature is 60 to 200 °C, preferably 75 to 80 °C; the drying time is 4 to 24 hours, preferably 10 to 12 hours;

[0048] The calcination temperature is 1000 to 1600 °C, preferably 1200 to 1500 °C; the calcination time is 2 to 12 hours, preferably 4 to 6 hours.

[0049] Further, in the step (5):

[0050] The copper salt is one or more of copper nitrate, copper sulfate, and copper chloride, and preferably copper nitrate;

[0051] The concentration of the copper salt is 3 to 9 mol / L, preferably 4 to 6 mol / L;

[0052] The impregnation method is one of excessive impregnation, spray impregnation, and equal-volume impregnation under vacuum conditions, and preferably excessive impregnation; the impregnation temperature is preferably 50 to 80 °C;

[0053] The vacuum degree is -50 to -100 kPa, preferably -70 to -90 kPa;

[0054] The stabilizing assistant is one or more of chromium nitrate, lanthanum nitrate, cerium nitrate, zirconium nitrate, and bismuth nitrate.

[0055] The thermal auxiliary material prepared by the method according to any one of the above, the specific surface area of the material is 0.5 to 20 m 2 / g, the mercury intrusion pore volume is 0.1 - 0.35 ml / g, the apparent density is 1.5 - 2.5 g / ml, and the radial side pressure strength ≥ 400 N / cm.

[0056] The third object of the present invention is to provide an application of a thermal auxiliary material in the alkane dehydrogenation reaction.

[0057] Furthermore, the above-mentioned thermal auxiliary material is used in the reaction of dehydrogenating alkanes to olefins.

[0058] Even further, the above-mentioned thermal auxiliary material is used in the reaction of directly dehydrogenating C2 - C5 alkanes to light olefins and is physically mixed with an alkane dehydrogenation catalyst for use.

[0059] Even further, in the above-mentioned application, the alkane dehydrogenation temperature is 380 - 900 °C, the pressure is -0.07 - 2.0 Mpa(g), and the mass hourly space velocity of the alkane is 0.3 - 5 h -1 ; the mass mixing ratio of the catalyst and the thermal auxiliary material is 0.5 - 10:1.

[0060] Furthermore, the preferred application conditions for alkane dehydrogenation are as follows:

[0061] The alkane raw material is preferably propane. The propane dehydrogenation catalyst and the thermal auxiliary material are mixed in a mass ratio of (0.5 - 10):1. The reaction form is preferably a fixed-bed batch reaction. The operating temperature is preferably 450 - 650 °C, the pressure is preferably -0.06 - -0.04 Mpa(g), and the mass hourly space velocity of propane is preferably 0.5 - 2 h -1 , the operating cycle is 20 - 40 min, and it includes steps such as dehydrogenation reaction, steam purging, air regeneration, hydrogen reduction, and nitrogen replacement.

[0062] Compared with the prior art, the positive effects of the present invention are reflected in:

[0063] (1) Using the coprecipitation method to precipitate or partially precipitate the carrier components can effectively improve the mixing degree of Al compounds and Ca compounds at the molecular level, providing favorable conditions for the formation of the next carrier precursor;

[0064] (2) The carrier precipitate material undergoes a high-temperature hydrothermal reaction, which is conducive to the formation of a calcium-aluminum compound precursor with a stable crystal form and structure. After high-temperature calcination, a CaO - Al 2 O 3 composite oxide with a dense structure and excellent heat storage performance can be formed;

[0065] (3) By adding a carrier promoter, the sintering temperature of the carrier is effectively reduced, while the shrinkage rate of the carrier is increased, promoting the discharge of micro pores in the carrier, improving the density and strength of the material, and reducing production energy consumption;

[0066] (4) By impregnating and ultrasonic oscillation under vacuum conditions to load active copper metal, the impregnation depth and uniformity in the carrier can be effectively improved, and through the spatial confinement effect of the stabilizing agent, the anti-sintering ability of the copper component during high-temperature operation can be effectively improved.

[0067] (5) In the present invention, through steps such as coprecipitation reaction, hydrothermal reaction at high temperature, calcination at high temperature, vacuum impregnation and ultrasonic oscillation, a thermal auxiliary material with high mechanical strength, anti-sintering, high heat transfer and high stability is synthesized; when this material is applied to an alkane dehydrogenation device, it is beneficial to improve the alkane conversion rate and olefin selectivity, extend the catalyst operation life, reduce the device energy consumption, etc. Brief Description of the Drawings

[0068] Figure 1 It is a schematic diagram of a propane dehydrogenation evaluation device;

[0069] Figure 2 It is a propane dehydrogenation cycle operation diagram (excerpt) participated by Example 9;

[0070] Figure 3 It is a propane dehydrogenation cycle operation diagram (excerpt) participated by Comparative Example 3. Specific Embodiments

[0071] All the features disclosed in this specification, or all the steps in the disclosed methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

[0072] Any feature disclosed in this specification (including the claims, abstract), unless specifically described, can be replaced by other equivalent or similar-purpose alternative features. That is, unless specifically described, each feature is only an example in a series of equivalent or similar features.

[0073] The following combines examples to further describe in detail the features and properties in the solution of the present invention.

[0074] In this application, the % without marking all represent mass percentages.

[0075] In the present invention, some conventional operating equipment, devices and components are omitted or only briefly described.

[0076] Example 1:

[0077] In this example, the component mass percentages of the thermal auxiliary material are: Al 2 O 3 : 75%, CaO: 15%, CuO: 9.5%, carrier assistant: 0.5%, stabilizing agent: 0%.

[0078] The preparation method of the thermal auxiliary material is:

[0079] S1: Weigh 551.9g aluminum nitrate nonahydrate, 63.0g calcium nitrate tetrahydrate, 3.2g magnesium nitrate hexahydrate and mix them evenly with an appropriate amount of water to prepare a mixed salt solution, and then drip them into a constant temperature reactor in parallel with the prepared excess sodium carbonate alkali solution, control the pH to 8.0, maintain the temperature of the reactor at 75°C, and age for 3h; obtain a carrier precipitate;

[0080] S2: The aged precipitated material was filtered and washed with 50°C hot water for 3 times, poured into a pulper and mixed for 1 hour, and then poured into a high-pressure hydrothermal stirring reactor, the stirring rate was set to 150 rpm, and the hydrothermal reaction was carried out at 200°C for 2 hours. After completion, the material was filtered and dried at 110°C to obtain a precursor powder;

[0081] S3: The dried precursor powder is added with 15% water and 0.5% pseudo-boehmite by weight, kneaded thoroughly, and then extruded into a strip shape through a die with a pore size of 4.0 mm.

[0082] S4: After drying the molded material at 80°C for 12 hours, place it in a high-temperature muffle furnace and calcine it at 1300°C for 4 hours;

[0083] S5: Weigh 250g of copper nitrate trihydrate and appropriate amount of water to prepare an excess impregnation solution with a concentration of 5.5mol / L, and pour it into a separatory funnel; take another 50.0g of the calcined extruded strip sample and put it into a dry suction filtration bottle, and evacuate it to -90kpa in a constant temperature water bath at 50℃, then use a separatory funnel to slowly add the impregnation solution into the suction filtration bottle to submerge the surface of the carrier, and perform vacuum impregnation for 0.5h; then, ultrasonically impregnate it in an ultrasonic oscillator at normal pressure for 0.5h;

[0084] S6: The impregnated sample was dried at 100°C for 10 hours and then calcined at 650°C for 4 hours to obtain a finished thermal auxiliary material.

[0085] Example 2

[0086] The composition weight percentage of the thermal auxiliary material in this embodiment is: Al 2 O 3 :70%, CaO:20%, 9%CuO, carrier additive:1.0%, stabilizing additive:0%.

[0087] The preparation method of the thermal auxiliary material is:

[0088] S1: Weigh 153.7g of calcium gluconate, 1.7g of barium nitrate and an appropriate amount of water and mix them evenly to prepare a mixed solution. Weigh 141.8g of sodium aluminate and an appropriate amount of water to prepare a sodium aluminate solution. The two streams of materials are dripped into a constant temperature reactor in parallel, and the pH is adjusted with sodium carbonate lye to control the pH to 10. Keep the temperature of the reactor at 80°C and age for 3h;

[0089] S2: Filter and wash the aged precipitated material three times with hot water at 50 °C, then pour it into a ball mill for wet ball milling for 2 h. Then pour it into a high-pressure hydrothermal stirring reactor, set the stirring rate at 150 rpm, and carry out hydrothermal reaction at 250 °C for 4 h. After completion, filter the material and dry it at 110 °C to obtain the precursor powder;

[0090] S3: Slowly add 11% water and 0.8% carboxymethyl cellulose based on the weight of the dried precursor powder for kneading, and then extrude it into strips through a mold with a pore size of 4.0 mm.

[0091] S4: Dry the formed material at 60 °C for 12 h, and then calcine it at 1500 °C for 2 h;

[0092] S5: Weigh 250 g of copper nitrate trihydrate and an appropriate amount of water to prepare an excessive impregnation solution with a concentration of 5.8 mol / L. Then add 50.0 g of the calcined extruded sample. After pumping to a vacuum of -90 kPa, carry out vacuum impregnation in a constant temperature water bath at 50 °C for 0.5 h; then under normal pressure, impregnate it in an ultrasonic oscillator for 1 h;

[0093] S6: Dry the impregnated sample at 110 °C for 10 h, and then calcine it at 500 °C for 4 h to prepare the finished heat-assisted material.

[0094] Example 3

[0095] In this example, the mass percentages of the components of the heat-assisted material are: Al 2 O 3 : 72%, CaO: 20%, CuO: 7%, carrier assistant: 1.0%, stabilizer assistant: 0%.

[0096] The preparation method of the heat-assisted material is as follows:

[0097] First step: Weigh 144.2 g of aluminum isopropoxide, 38.7 g of calcium chloride, 3.9 g of nickel nitrate hexahydrate and an appropriate amount of water and mix them evenly to prepare a mixed salt solution. Drop it into the constant temperature reactor in parallel with the prepared excessive sodium hydroxide alkali solution, control the pH to 8.5, keep the temperature of the reactor at 75 °C, and age for 3 h;

[0098] Second step: Filter and wash the aged material three times with hot water at 50 °C, pour it into a pulper and mix for 1 h, then pour it into a high-pressure hydrothermal stirring reactor, set the stirring rate at 150 rpm, heat up to 180 °C, and carry out hydrothermal reaction for 8 h. After completion, filter the material and dry it at 110 °C to obtain the precursor powder;

[0099] Third step: Add 15% water and 0.5% carboxymethyl cellulose based on the weight of the dried precursor powder for kneading, and then extrude it into strips through a mold with a pore size of 4.0 mm.

[0100] Step 4: After drying the formed material at 90 °C for 12 h, calcine it at 1400 °C for 2 h;

[0101] Step 5: Weigh 250 g of copper nitrate trihydrate and an appropriate amount of water to prepare an excessive impregnation solution with a concentration of 5.0 mol / L. Then add 50.0 g of the calcined extruded sample. After pumping to a vacuum of -90 kPa, carry out vacuum impregnation in a constant temperature water bath at 50 °C for 0.5 h; then impregnate it in an ultrasonic oscillator under normal pressure for 1 h;

[0102] Step 6: After drying the impregnated sample at 110 °C for 10 h, calcine it at 700 °C for 6 h to obtain the finished product.

[0103] Example 4

[0104] In this example, the component mass percentages of the thermal auxiliary material are: Al 2 O 3 : 73%, CaO: 20%, CuO: 6.8%, carrier assistant: 0.2%, stabilizer assistant 0%.

[0105] The preparation method of the thermal auxiliary material is as follows:

[0106] Step 1: Weigh 544.4 g of aluminum nitrate nonahydrate, 63.2 g of calcium nitrate tetrahydrate, 1.0 g of iron(III) nitrate nonahydrate and an appropriate amount of water, and uniformly mix them to prepare a mixed salt solution. Then flow it into a constant temperature reaction kettle together with the prepared excessive sodium hydroxide lye, control the pH to 9.0, keep the temperature of the reaction kettle at 80 °C, and age for 3 h;

[0107] Step 2: Filter and wash the aged material twice with hot water at 50 °C, put it into a pulper and mix for 1 h, then pour it into a high-pressure hydrothermal stirring reaction kettle, set the stirring rate to 150 rpm, 200 °C, carry out hydrothermal reaction for 10 h. After completion, filter the material and dry it at 110 °C to obtain the precursor powder;

[0108] Step 3: Add water with a weight of 15% of the dried precursor powder and 0.5% of aluminum stearate for granulation, and then press it into tablets.

[0109] Step 4: After drying the formed material at 100 °C for 12 h, calcine it at 1400 °C for 2 h;

[0110] Step 5: Weigh 250 g of copper nitrate trihydrate and an appropriate amount of water to prepare an excessive impregnation solution with a concentration of 4.5 mol / L. Then add 50.0 g of the calcined extruded sample. After pumping to a vacuum of -90 kPa, carry out vacuum impregnation in a constant temperature water bath at 50 °C for 0.5 h; then impregnate it in an ultrasonic oscillator under normal pressure for 1 h;

[0111] Step 6: After the impregnated sample is dried at 100°C for 10 h, it is calcined at 600°C for 4 h to obtain the finished product.

[0112] Example 5

[0113] In this example, the component mass percentages of the thermal auxiliary material are: Al 2 O 3 : 72%, CaO: 20%, CuO: 6.5%, carrier assistant: 1.0%, stabilizing assistant: 0.5%.

[0114] The preparation method of the thermal auxiliary material is as follows:

[0115] Step 1: Weigh 529.4 g of aluminum nitrate nonahydrate, 70.0 g of calcium nitrate tetrahydrate, 6.4 g of magnesium nitrate hexahydrate and an appropriate amount of water, and uniformly mix them to prepare a mixed salt solution. Then, flow the prepared excessive potassium hydroxide alkali solution into a constant temperature reaction kettle, control the pH to 8.0, keep the temperature of the reaction kettle at 80°C, and age for 3 h;

[0116] Step 2: Filter and wash the aged material twice with hot water at 50°C, put it into a pulper and mix for 2 h, then pour it into a high-pressure hydrothermal stirring reaction kettle, set the stirring rate to 150 r / min, carry out hydrothermal reaction at 220°C for 4 h, filter the material after completion, and dry it at 110°C to obtain the precursor powder;

[0117] Step 3: Add 12% water and 0.5% pseudo-boehmite based on the weight of the dried precursor powder for kneading, and then extrude and form through a die with a pore diameter of 4.0 mm;

[0118] Step 4: After drying the formed material at 80°C for 12 h, calcine it at 1300°C for 4 h;

[0119] Step 5: Weigh 250 g of copper nitrate trihydrate and 33.6 g of chromium nitrate nonahydrate, add an appropriate amount of water to prepare an excessive impregnation mixed solution, then add 50.0 g of the calcined extruded sample, pump it to a vacuum of -90 kPa, and carry out vacuum impregnation in a constant temperature water bath at 50°C for 0.5 h; then impregnate it in an ultrasonic oscillator under normal pressure for 1 h;

[0120] Step 6: After the impregnated sample is dried at 110°C for 12 h, it is calcined at 500°C for 4 h to obtain the finished product.

[0121] Example 6

[0122] In this example, the component mass percentages of the thermal auxiliary material are: Al 2 O 3 : 75%, CaO: 15%, CuO: 8%, carrier assistant: 1.0%, stabilizing assistant: 1.0%.

[0123] The preparation method of the thermal auxiliary material is as follows:

[0124] Step 1: Weigh 551.9 g of aluminum nitrate nonahydrate, 63.2 g of calcium nitrate tetrahydrate, 6.4 g of magnesium nitrate hexahydrate and an appropriate amount of water, and uniformly mix them to prepare a mixed salt solution. Then, flow the mixed salt solution and the prepared excessive sodium carbonate alkaline solution into a constant-temperature reaction kettle in parallel, control the pH to 8.5, keep the temperature of the reaction kettle at 75 °C, and age for 3 h;

[0125] Step 2: Filter and wash the aged material 3 times with hot water at 50 °C, put it into a pulper and mix for 1 h, then pour it into a high-pressure hydrothermal stirring reaction kettle, set the stirring rate to 150 r / min, carry out hydrothermal reaction at 200 °C for 12 h, filter the material after completion, and dry it at 110 °C to obtain the precursor powder;

[0126] Step 3: Add 20% of water and 0.5% of sesbania powder by weight to the dried precursor powder, knead them, and then extrude and form them through a mold with a pore diameter of 4.0 mm.

[0127] Step 4: Dry the formed material at 110 °C for 12 h, and then calcine it at 1300 °C for 4 h;

[0128] Step 5: Weigh 250 g of copper nitrate trihydrate and 36.67 g of lanthanum nitrate hexahydrate, add an appropriate amount of water to prepare an excessive impregnation mixed solution, then add 50.0 g of the calcined extruded sample, pump it to a vacuum of -90 kPa, and carry out vacuum impregnation in a constant-temperature water bath at 50 °C for 0.5 h; then impregnate it in an ultrasonic oscillator under normal pressure for 0.5 h;

[0129] Step 6: Dry the impregnated sample at 120 °C for 10 h, and then calcine it at 450 °C for 6 h to obtain the finished product.

[0130] Example 7

[0131] In this example, the component mass percentages of the thermal auxiliary material are: Al 2 O 3 : 75%, CaO: 17%, CuO: 6%, carrier assistant: 1.0%, stabilizer assistant: 1.0%.

[0132] The preparation method of the thermal auxiliary material is as follows:

[0133] Step 1: Weigh 551.9 g of aluminum nitrate nonahydrate, 71.6 g of calcium nitrate tetrahydrate, 1.7 g of barium nitrate and an appropriate amount of water, and uniformly mix them to prepare a mixed salt solution. Then, flow the mixed salt solution and the prepared excessive sodium hydroxide alkaline solution into a constant-temperature reaction kettle in parallel, control the end point pH to 9.0, keep the temperature of the reaction kettle at 80 °C, and age for 3 h;

[0134] Step 2: Filter and wash the aged material three times with hot water at 50°C, then put it into a pulper and mix for 1 h. Next, pour it into a high-pressure hydrothermal stirring reactor, set the stirring rate at 150 rpm, and carry out hydrothermal reaction at 230°C for 5 h. After completion, filter the material and dry it at 110°C to obtain the precursor powder;

[0135] Step 3: Slowly add 15% water and 1% aluminum sol by weight of the dried precursor powder and knead them, then extrude and form through a mold with a pore size of 4.0 mm.

[0136] Step 4: Dry the formed material at 100°C for 12 h, and then calcine it at 1200°C for 8 h;

[0137] Step 5: Weigh 250.0 g of copper nitrate trihydrate and 34.8 g of cerium nitrate, and prepare an excessive impregnation mixed solution with appropriate water. Then add 50.0 g of the calcined extruded sample, pump it to a vacuum of -90 kPa, and carry out vacuum impregnation in a constant temperature water bath at 50°C for 0.5 h; then impregnate it in an ultrasonic oscillator under normal pressure for 0.5 h;

[0138] Step 6: Dry the impregnated sample at 100°C for 10 h, and then calcine it at 580°C for 4 h to obtain the finished product.

[0139] Example 8

[0140] In this example, the mass percentage of the components of the thermal auxiliary material is: Al 2 O 3 : 73%, CaO: 20%, CuO: 6%, carrier assistant: 0%, stabilizing assistant: 1.0%.

[0141] The preparation method of the thermal auxiliary material is as follows:

[0142] Step 1: Weigh 295.3 g of aluminum isopropoxide and 84.3 g of calcium nitrate tetrahydrate, and uniformly mix them with appropriate water to prepare a mixed salt solution. Then, add the prepared excessive sodium carbonate alkaline solution dropwise into the constant temperature reactor in a concurrent flow manner, control the pH to 8.5, keep the temperature of the reactor at 75°C, and age for 3 h;

[0143] Step 2: Filter and wash the aged material twice with hot water at 50°C, then put it into a pulper and mix for 1 h. Next, pour it into a high-pressure hydrothermal stirring reactor, set the stirring rate at 200 rpm, and carry out hydrothermal reaction at 230°C for 5 h. After completion, filter the material and dry it at 110°C to obtain the precursor powder;

[0144] Step 3: Slowly add 17% water and 0.5% of powdered sesbania by weight of the dried precursor powder and knead them, then extrude and form through a mold with a pore size of 4.0 mm.

[0145] Step 4: After drying the formed material at 100°C for 12 h, calcine it at 1450°C for 2 h;

[0146] Step 5: Weigh 250.0 g of copper nitrate trihydrate and 48.1 g of zirconium nitrate pentahydrate, and prepare an excessive impregnation mixed solution with appropriate water. Then add 50.0 g of the calcined extruded sample. After pumping to a vacuum of -90 kPa, carry out vacuum impregnation in a constant temperature water bath at 50°C for 0.5 h; then impregnate it in an ultrasonic oscillator under normal pressure for 0.5 h;

[0147] Step 6: After drying the impregnated sample at 100°C for 10 h, calcine it at 700°C for 6 h to obtain the finished product.

[0148] Example 9

[0149] In this example, the component mass percentages of the thermal auxiliary material are: Al 2 O 3 : 75%, CaO: 15%, CuO: 8.7%, carrier assistant: 1.0%, stabilizing assistant: 0.3%.

[0150] The preparation method of the thermal auxiliary material is as follows:

[0151] Step 1: Weigh 551.9 g of aluminum nitrate nonahydrate, 63.2 g of calcium nitrate tetrahydrate, and 6.4 g of magnesium nitrate hexahydrate, and uniformly mix them with appropriate water to prepare a mixed salt solution. Then flow and drip it into a constant temperature reaction kettle together with the prepared excessive sodium carbonate alkali solution, control the pH to 8.5, keep the temperature of the reaction kettle at 75°C, and age for 3 h;

[0152] Step 2: Filter and wash the aged material 3 times with hot water at 50°C, then put it into a pulper and mix for 1 h. Then pour it into a high-pressure hydrothermal stirring reaction kettle, set the stirring rate to 100 r / min, carry out hydrothermal reaction at 250°C for 4 h. After completion, filter the material and dry it at 110°C to obtain the precursor powder;

[0153] Step 3: Add 15% water and 0.2% sesbania powder by weight to the dried precursor for kneading, and then extrude and form it through a mold with a pore diameter of 4.0 mm.

[0154] Step 4: After drying the formed material at 80°C for 12 h, calcine it at 1340°C for 4 h;

[0155] Step 5: Weigh 250.0 g of copper nitrate trihydrate and 15.0 g of chromium nitrate nonahydrate, and add appropriate water to prepare an excessive impregnation mixed solution. Then add 50.0 g of the calcined extruded sample. After pumping to a vacuum of -90 kPa, carry out vacuum impregnation in a constant temperature water bath at 50°C for 0.5 h; then impregnate it in an ultrasonic oscillator under normal pressure for 1 h;

[0156] Step 6: After drying the impregnated sample at 110°C for 12 h, it is calcined at 680°C for 4 h to obtain the finished product.

[0157] Comparative Example 1

[0158] In this comparative example, the component mass percentages of the thermal auxiliary material are as follows: Al 2 O 3 : 77%, CaO: 15%, CuO: 8%; Different from the examples, the carrier is prepared by the common solid mixing method and no additives are added.

[0159] The specific preparation process is as follows:

[0160] Step 1: Physically mix 120 g of pseudo-boehmite and 20.0 g of calcium hydroxide in a ball mill for 5 h. After mixing, slowly add 30.0 mL of water and 1% aluminum sol for kneading, and finally extrude into strips.

[0161] Step 2: After drying the formed material from Step 1 at 100°C for 12 h, the dried material is calcined at 1400°C for 4 h.

[0162] Step 3: Weigh 250 g of copper nitrate trihydrate according to its water absorption rate, add an appropriate amount of water to prepare an excessive impregnation solution, and then add 50 g of the calcined extruded sample for normal-temperature impregnation.

[0163] Step 4: After drying the impregnated sample at 100°C for 10 h, it is calcined at 600°C for 4 h to obtain the finished product of the comparative example.

[0164] Comparative Example 2

[0165] In this comparative example, both the component mass percentage and the preparation method of the thermal auxiliary material are the same as those in Example 9. The only difference is that: the aged material obtained in the S1 process is directly dried at 110°C without performing the S2 step, and the finished product of the comparative example is obtained through the S3 - S6 preparation steps.

[0166] Comparative Example 3

[0167] Samples of commercial heating materials used in a domestic propane dehydrogenation to propylene industrial device.

[0168] Testing:

[0169] The finished products / samples obtained in the above examples and comparative examples are respectively characterized by their physical and chemical properties and evaluated on a propane dehydrogenation evaluation device.

[0170] (I) Physical and chemical property characterization

[0171] In this part, the finished heating material products obtained in the above examples and comparative examples are selected for physical and chemical property characterization, mainly analyzing the nitrogen adsorption specific surface area, mercury intrusion pore volume, bulk density, and radial side pressure strength of each sample.

[0172] Analytical instruments used: For the nitrogen adsorption analyzer, the Micromeritics ASAP 2460 nitrogen adsorption analyzer from the United States is adopted; for the mercury intrusion analyzer, the AutoPore IV 9500 2.03.01 mercury intrusion instrument from Micromeritics of the United States is used; the determination methods for apparent density and radial side pressure strength refer to the well-known industry standards in this industry. The specific determination results are summarized in Table 1.

[0173] Table 1 Summary of the physical and chemical properties of the finished products in the examples and comparative examples

[0174]

[0175] As can be seen from Table 1, for Examples 1-9 using the preparation method described in this invention patent, the specific surface area of the thermal auxiliary material is 1-6 m 2 / g, the mercury intrusion pore volume is 0.1-0.35 ml / g, the apparent density is 1.6-2.5 g / ml, and the radial side pressure strength ≥ 400 N / cm. Compared with Comparative Examples 1-2, it has higher mechanical strength. This may be because the coprecipitation method and hydrothermal synthesis greatly promote the mutual combination between calcium and aluminum, thereby forming a dense calcium aluminate spinel. However, with the differences in the type, content, hydrothermal temperature, and calcination temperature of the carrier additives, the apparent density of the formed material also changes. In particular, the thermal auxiliary materials prepared in Examples 5, 6, and 9 not only have better mechanical strength than the sample in Comparative Example 3, but also their specific surface area, pore volume, and apparent density are similar to those in Comparative Example 3.

[0176] (II) Evaluation and test of propane dehydrogenation performance

[0177] The promoting effects of Examples 1-9 and the comparative examples on the propane dehydrogenation to propylene reaction were evaluated on a fixed-bed batch reactor. The schematic diagram of the specific device is shown in the appendix Figure 1 as shown.

[0178] For each propane dehydrogenation test, 25 g of the thermal auxiliary material from each example and comparative example was uniformly mixed with 35 g of the same commercial chromium-based propane dehydrogenation catalyst and loaded into a high-temperature reaction tube with a ceramic inner lining of Φ40 mm; the operating temperature was set at 580 °C, the reaction pressure was -0.05 Mpa(g), the propane mass space velocity was 0.9 h -1 , the operating cycle was 30 min, which included a dehydrogenation reaction of 600 s, a nitrogen purge of 150 s, a steam purge of 100 s, an air regeneration of 640 s, a nitrogen replacement of 150 s, and a hydrogen reduction of 160 s. Each sample was continuously cycled 50 times, and a comprehensive sample of the outlet gas was taken each time and analyzed on an Agilent 8860 gas chromatograph. The analysis results corresponding to 5 times and 50 times of each sample are listed in Table 2.

[0179] Table 2 Propane dehydrogenation conversion rate and selectivity of the finished products of the thermal auxiliary materials in the examples and comparative examples

[0180]

[0181] Among them, the blank sample replaces the heat-assisted material with inert Al 2 O 3 The dehydrogenation reaction process of the particles; The partial cycle operation diagrams and single-run diagrams of Example 9 are shown in the appendix Figure 2 ; The partial cycle operation diagrams and single-run diagrams of Comparative Example 3 are shown in the appendix Figure 3 .

[0182] Table 3 Comparison of copper grain sizes before and after use in Examples and Comparative Examples

[0183]

[0184] As can be seen from Table 2, Examples 1-9 have higher propane conversion rates and propylene selectivities compared with Comparative Example 1 and the blank example; In particular, Example 9 has better conversion rate and selectivity, which benefits from its stable carrier structure and stable heat release efficiency. The blank sample without using any heat-assisted material deactivates due to carbon deposition quickly because the regeneration temperature is too low; In addition, compared with Comparative Example 2, Example 9 is mainly reflected in the dense structure of the carrier, which can ensure its stable promotion of propane dehydrogenation reaction during the cyclic reaction without large performance fluctuations. Secondly, the stable carrier is also beneficial to the impregnation of the heat-generating component without causing the carrier to crack and collapse after impregnation; Compared with Comparative Example 3, combining the appendix Figure 2 and the appendix Figure 3 , it can be seen that the operation diagrams of the heat-assisted material prepared by the present invention and the commercial heat-generating material are extremely similar, but due to better heat release performance, the promotion effect on the propane dehydrogenation catalyst is significantly better than that of the commercial heat-generating material, reflecting the beneficial and innovative nature of this invention patent.

[0185] The data in Table 3 further illustrate that the heat-assisted materials prepared in Examples 5, 6, 7, 8, and 9 using stable additives have better copper dispersion and smaller particle sizes. After 50 cycles of operation, the copper grains basically do not change or become smaller; while obvious increases in copper grain sizes occur in Examples 1, 2, 3, 4 without adding stable additives and Comparative Examples 1 and 2. Therefore, the addition of stable additives is beneficial to maintaining the stability of the active component during high-temperature operation.

[0186] The above-described embodiments only represent the specific implementation manners of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the protection scope of this application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the technical solution of this application, several deformations and improvements can still be made, and these all belong to the protection scope of this application.

[0187] This Background of the Invention section is provided to generally present the context of the present invention. Work of the presently named inventors, to the extent it is described in this Background of the Invention section, and aspects of the work that are not yet prior art as of the filing date of this application, are neither expressly nor impliedly admitted to be prior art to the present invention.

Claims

1. A thermal auxiliary material for promoting the efficiency of alkane dehydrogenation reaction, characterized in that: The auxiliary material comprises a heating body, a heat storage carrier, a stabilizing agent and a carrier agent; wherein: the heating body component is CuO; the heat storage carrier component is a CaO-Al2O3 composite oxide; the stabilizing agent is one or more of Cr2O3, La2O3, CeO2, and ZrO2; the carrier agent is one or more of MgO, BaO, NiO, and Fe2O3; calculated as oxides, the mass percentage of each component in the auxiliary material is: 4wt.% to 15wt.% CuO, 10wt.% to 20wt.% CaO, 65wt.% to 80wt.% Al2O3, 0.3wt.% to 3wt.% stabilizing agent and 1wt.% to 3wt.% carrier agent, and the sum of the total mass percentage is 100%; The method for preparing the thermal auxiliary material comprises the following specific steps: (1) First, an aluminum compound, a calcium compound, a salt of a carrier auxiliary agent and desalted water are mixed to form a mixed solution, and then an alkaline precipitant is added, and a one-step or two-step co-precipitation is performed to control the pH value to be 6.5-12.0 to obtain a mixed precipitate; and then aging is performed at a temperature of 60-95°C for a time of 2-10 hours; (2) After filtering, washing, beating or wet grinding the aged material in step (1), pour it into a high-pressure hydrothermal stirring reactor, set the stirring rate to 80-300 rpm, raise the temperature to 120-250°C, and perform hydrothermal reaction in a closed state for 2-24 hours, filter the reaction material again, and dry it at 80-200°C to obtain a precursor powder; (3) adding 10-20% by weight of water to the dried precursor powder in step (2) for kneading, and adding a binder for extrusion or ball forming, or adding a release agent for tableting; (4) drying and calcining the molded material in step (3); (5) impregnating the shaped material calcined in step (4) with a mixed solution containing a salt for forming copper oxide and a salt for forming a stabilizing aid in a vacuum environment, and then shaking it in an ultrasonic device; (6) The sample impregnated in step (5) is dried at 100-200° C. for 2-12 h, and then calcined at 400-900° C. for 2-10 h to obtain a finished thermal auxiliary material.

2. The thermal assist material according to claim 1, characterized in that: In step (1), The aluminum compound is one or more of aluminum nitrate, aluminum sulfate, aluminum chloride, aluminum isopropoxide, basic aluminum carbonate, sodium aluminate, aluminum hydroxide, gibbsite, bayerite, norlite, boehmite, and pseudo-boehmite; The calcium compound is one or more of calcium nitrate, calcium chloride, calcium bicarbonate, calcium gluconate, calcium hydrogen malate, calcium sulfate, calcium hydroxide, and calcium carbonate; The salt of the carrier auxiliary agent is one or more of magnesium nitrate, barium nitrate, nickel nitrate and iron nitrate; The alkaline precipitant is one or more of sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium hydroxide, potassium carbonate and ammonia water.

3. The thermal assist material according to claim 1, characterized in that: In step (2), The washing step uses hot water at room temperature to 80°C for 2 to 4 times; In the beating or wet grinding step, a beating machine or a wet ball mill is used to further evenly mix the washed materials, and the mixing time is 1 to 3 hours.

4. The thermal assist material according to claim 1, characterized in that: In step (3), The binder is one or more of carboxymethyl cellulose, field pine powder, polyvinyl alcohol, aluminum sol, and pseudo-boehmite; The amount of the binder added is 0-2% of the weight of the precursor powder; The release agent is one or more of graphite, magnesium stearate, aluminum stearate, and calcium stearate; The added amount of the release agent is 0-1% of the weight of the precursor powder.

5. The thermal assist material according to claim 1, characterized in that: In step (4), The drying temperature is 60-200°C and the drying time is 4-24h; The calcination temperature is 1000-1600°C, and the calcination time is 2-12h.

6. The thermal assist material according to claim 1, characterized in that: In step (5), The salt forming copper oxide is one or more of copper nitrate, copper sulfate and copper chloride; The solution concentration of the salt forming copper oxide is 3-9 mol / L; The impregnation method is one of excessive impregnation, spray impregnation, and equal volume impregnation under vacuum conditions; the impregnation temperature is 50-80° C., the impregnation time is 0.5-2 hours; and the impregnation is performed in an ultrasonic device for 0.5-2 hours; The vacuum degree is -50~-100kpa; The salt of the stabilizing aid is one or more of chromium nitrate, lanthanum nitrate, cerium nitrate and zirconium nitrate.

7. Use of the thermal auxiliary material according to any one of claims 1 to 6 in the dehydrogenation of alkanes to produce olefins.

8. The use according to claim 7, characterized in that It is used in the direct dehydrogenation of C2~C5 alkanes to produce low-carbon olefins, and is physically mixed with an alkane dehydrogenation catalyst; the alkane dehydrogenation temperature is 380~900℃, the pressure is -0.07~2.0Mpa(g), and the alkane mass space velocity is 0.3~5h -1 ; The mass mixing ratio of the catalyst and the thermal auxiliary material is 0.5~10:1.

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