A preparation method of in-situ heat-generating particles, in-situ heat-generating particles and applications thereof

Abstract

The present invention belongs to the field of deep processing of low-carbon alkanes, and discloses a preparation method of in-situ heat-generating particles, in-situ heat-generating particles and applications thereof. The preparation method of in-situ heat-generating particles comprises the following steps: S1. Evenly mix a metal salt, a carrier and a flux to obtain a mixture; subject the mixture to a high-temperature melting treatment and cooling; S2. Grind the product obtained in step S1 into powder; S3. Add the product obtained in step S2 to a metal salt aqueous solution for impregnation; S4. Dry and shape the product obtained in step S3 and then roast it. The in-situ heat-generating particles are mixed with a dehydrogenation catalyst in the dehydrogenation of low-carbon alkanes in a fluidized bed, which can solve the problem of heat supply in the existing fluidized bed technology, reduce or eliminate the fuel replenishment during the catalyst coking regeneration process; and can avoid the side reactions such as thermal cracking and coking caused by the direct contact between the high-temperature regenerated catalyst and the raw hydrocarbon when adding fuel, thereby improving the reaction selectivity and the yield of the target product.

Description

Technical Field

[0001] The present invention belongs to the field of deep processing of low-carbon alkanes, relates to the dehydrogenation of low-carbon alkanes, and specifically relates to a preparation method of in-situ heating particles, in-situ heating particles and applications thereof. Background Art

[0002] The dehydrogenation of low-carbon alkanes is a special process for producing olefins with the same carbon number, such as ethane dehydrogenation to ethylene, propane dehydrogenation to propylene, isobutane dehydrogenation to isobutylene, n-butane dehydrogenation to butene, isopentane dehydrogenation to isopentene, etc. In industry, the dehydrogenation process of low-carbon alkanes usually adopts fixed bed technology and moving bed technology. However, due to the strong endothermic effect of the dehydrogenation reaction of low-carbon alkanes and the easy coking and deactivation of catalysts, the dehydrogenation process usually requires timely heat supply and frequent coke regeneration. Therefore, in fixed bed dehydrogenation technology (such as Catofin), highly frequent valve switching and complex intermittent cycle control such as reaction-purge-regeneration-reduction are required; in moving bed dehydrogenation technology (such as Oleflex), the inter-stage reactor logistics need to be reheated, which consumes a lot of energy. In view of this, the development of circulating fluidized bed dehydrogenation technology with efficient heat-mass transfer and continuous reaction-regeneration operation has become an ideal choice. Therefore, most of the new technologies successfully developed in recent years belong to this category, such as the ADHO technology developed by China University of Petroleum (East China), the FCDh technology developed by Dow, and the K-PRO developed by KBR, all of which use fluidized bed reactors.

[0003] In the dehydrogenation process of low-carbon alkanes, it is usually necessary to control the amount of coke on the catalyst surface within a certain range, so that its active sites are fully covered or its fluidization and reaction performance are seriously affected. Therefore, the amount of carbon deposits on the catalyst is usually small. If the heat released by the catalyst coke regeneration process is relied upon alone, the heat required for the dehydrogenation reaction process cannot be met at all. For this reason, in the fluidized bed, especially the circulating fluidized bed dehydrogenation process, it is usually necessary to add additional fuel to the catalyst regenerator to generate more heat and accumulate it in the regenerated catalyst. However, when the high-temperature regenerated catalyst circulates to the dehydrogenation reactor and contacts with gaseous hydrocarbon substances, it is easy to cause side reactions such as thermal cracking and coke formation, resulting in a sharp decline in the selectivity of the target product olefins. Therefore, it is urgent to solve the problem of heat supply in the existing fluidized bed technology. Summary of the invention

[0004] In view of the shortcomings of the above-mentioned prior art, the present invention provides a method for preparing in-situ heat-generating particles, in-situ heat-generating particles and their application. The in-situ heat-generating particles prepared by the present invention are physically mixed with dehydrogenation catalyst particles and applied to the fluidized bed dehydrogenation of low-carbon alkanes, which can solve the heat supply problem in the existing fluidized bed technology.

[0005] The specific technical solutions are as follows:

[0006] One of the purposes of the present invention is to provide a method for preparing in-situ heat-generating particles, comprising the following steps:

[0007] S1. The metal salt, the carrier and the flux are mixed to obtain a mixture; the mixture is subjected to a high temperature melting treatment and cooled;

[0008] S2. The product obtained in step S1 is ground into powder;

[0009] S3. The product obtained in step S2 is added to an aqueous solution of a metal salt for impregnation;

[0010] S4. The product obtained in step S3 is dried, formed and then calcined.

[0011] The present invention obtains an in-situ heating particle through the above-mentioned preparation method, wherein a part of the metal is doped into the carrier, and the other part is loaded on the carrier by impregnation. The particle size range of the in-situ heating particles obtained by the above-mentioned preparation method is preferably 20~250 μm, and the average particle size is 60~80 μm. The above-mentioned in-situ heating particles are mixed with a dehydrogenation catalyst and applied to the dehydrogenation of low-carbon alkanes in a fluidized bed. It can provide part or all of the heat required for the dehydrogenation reaction in situ in the alkane dehydrogenation fluidized bed reactor, while reducing or eliminating the fuel replenishment during the catalyst coking regeneration process, thereby avoiding the occurrence of side reactions such as thermal cracking and coking caused by direct contact between the high-temperature regenerated catalyst and the raw hydrocarbon, thereby improving the selectivity of the reaction and the yield of the target product.

[0012] Furthermore, in step S1 and step S3: the metal salt is at least one of antimony salt, iron salt, magnesium salt, manganese salt and cadmium salt.

[0013] Furthermore, in step S1 and step S3: the metal salt is a metal halide and / or a nitrate.

[0014] Further, in step S1: the carrier is at least one of alumina, diatomaceous earth, silica gel, anatase, and molecular sieve.

[0015] Further, in step S1: the flux is sodium chloride and / or potassium chloride.

[0016] Furthermore, in step S1: the mass ratio of the metal salt to the carrier is 1:(1-10).

[0017] Furthermore, in step S1: the mass ratio of the metal salt to the co-solvent is 1:(1-10).

[0018] Furthermore, in step S1: the metal salt, the carrier and the flux are mixed and then preferably ground in a ball mill for 2 to 5 hours, and the grinding speed is preferably 100 to 120 rpm.

[0019] Furthermore, in step S1, the conditions for high temperature melting treatment are preferably: melting temperature 750-1100°C, heating rate 2-10°C / min, and holding time 5-10 h.

[0020] Furthermore, in step S2: before grinding, the product obtained in step S1 is washed and dried in advance.

[0021] Specifically, in step S2: washing with deionized water, preferably washing until the conductivity of the filtrate is less than 80 μS / cm.

[0022] Specifically, in step S2: the drying is preferably oven drying; the drying temperature is 70-140° C., and the drying time is 6-12 h.

[0023] Furthermore, in step S4: the drying is spray drying; the spray drying temperature is preferably 200-300° C. The product obtained in step S3 is spray dried into microspheres, and then calcined to obtain microsphere particle products.

[0024] Furthermore, in step S3: the pulping is uniformly performed during the impregnation process to form a thin paste for spray drying. The pulping time (i.e., the impregnation time) is preferably 2 to 5 hours.

[0025] Furthermore, in step S4, the calcination conditions are preferably: calcination temperature 500-800°C, heating rate 2-10°C / min, and holding time 5-10 h. The calcination is preferably carried out in an air atmosphere.

[0026] The second object of the present invention is to provide in-situ heat-generating particles obtained by the above preparation method. The in-situ heat-generating particles obtained by the above preparation method have a particle size range of 20-250 μm, an average particle size of 60-80 μm, and a density of 1750-1850 kg / m 3 , which can be applied to the dehydrogenation of light alkanes in a fluidized bed.

[0027] The third object of the present invention is to provide the application of the above-mentioned in-situ heat-generating particles in the dehydrogenation of low-carbon alkanes in a fluidized bed.

[0028] Furthermore, the in-situ heat-generating particles are mixed with the dehydrogenation catalyst in the fluidized bed for use in the dehydrogenation of low-carbon alkanes. The in-situ heat-generating particles of the present invention are inert to the side reactions such as thermal cracking and coking in the process of alkane dehydrogenation, and can release heat in both the oxidation (regenerator) and reduction (reactor) atmospheres, or at least release in-situ in the reduction atmosphere not less than the heat required for the dehydrogenation reaction; when mixed with the dehydrogenation catalyst particles, the heat supply problem in the existing fluidized bed technology can be solved.

[0029] Wherein, the fluidized bed is a fixed fluidized bed or a circulating fluidized bed.

[0030] Wherein, the low carbon alkane is preferably at least one of ethane, propane, isobutane, n-butane and isopentane.

[0031] Specifically, the dehydrogenation catalyst is preferably a microspherical granular catalyst based on chromium or tungsten; the particle size range of the dehydrogenation catalyst is preferably 20~200 μm, and the average particle size is 60~80 μm. The particle density of the in-situ heating particles is preferably equivalent to the particle density of the dehydrogenation catalyst. The in-situ heating particles preferably have a particle size range of 20~250 μm, and there is a certain amount (10%~20%) of heating particles that are larger than the maximum particle size of the dehydrogenation catalyst. The dehydrogenation catalyst can specifically be selected from the dehydrogenation catalyst disclosed in the invention patent "A high-strength low-carbon alkane dehydrogenation catalyst and its preparation method" developed by the applicant team of the present invention and application number CN201410265574.1.

[0032] When two particles of the same density are co-fluidized, whether the result is stratification or uniform mixing depends on the particle size of the two particles; the commonly used dehydrogenation catalyst for fluidized bed is 20~200 μm, and within this particle size range, the fluidization performance of the particles is good; the particle size of the heat-generating particles of the present invention is controlled to be 20~250 μm, in order to ensure that a certain amount of heat-generating particles are distributed in the lower part of the fluidized bed under the premise of ensuring good fluidization performance of similar dehydrogenation catalysts, for preheating the alkane feedstock entering from the bottom of the fluidized bed; at the same time, it is also necessary to ensure that a certain amount of heat-generating particles is not much different from the particle size of the dehydrogenation catalyst, in order to achieve uniform mixing with the dehydrogenation catalyst in the upper part of the fluidized bed to provide the heat absorption required for the reaction. Specifically, in the operation of the circulating fluidized bed: 90%~100% of the particles within the range of 0~30 cm above the gas distribution plate in the fluidized bed reactor are heat-generating particles; outside this range, the heat-generating particles are uniformly mixed with the dehydrogenation catalyst particles, that is, there is "lower grading and upper mixing" in the alkane dehydrogenation fluidized bed reactor.

[0033] Specifically, the mixing mass ratio of the in-situ heat-generating particles to the dehydrogenation catalyst is preferably 1:(1-10).

[0034] Specifically, in the circulating fluidized bed dehydrogenation of light alkanes, the mass ratio of the dehydrogenation of light alkanes to the total circulation amount of particles (the total circulation amount of in-situ heat-generating particles and dehydrogenation catalyst particles) is preferably 1:(1~10).

[0035] The beneficial effects of the present invention are as follows:

[0036] The in-situ heat-generating particles proposed in the present invention are mixed with the dehydrogenation catalyst to solve the heat supply problem in the existing fluidized bed technology, that is, to provide part or all of the heat required for the dehydrogenation reaction in situ in the alkane dehydrogenation fluidized bed reactor, reduce or eliminate the fuel supply during the catalyst burning regeneration process, and reduce carbon emissions; and can avoid the occurrence of side reactions such as thermal cracking and coking caused by direct contact between the high-temperature regenerated catalyst and the raw hydrocarbon when adding fuel, thereby improving the reaction selectivity and the yield of the target product; it has very important application value in the field of petroleum hydrocarbon processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the circulating fluidized bed reaction regeneration device and process flow used in Application Example 2;

[0038] Figure 2 This is a SEM scanning electron microscope image of the in-situ heating particles obtained in Example 1;

[0039] Figure 1 In: 1. First heating furnace; 2. Fluidized bed reactor; 3. First ceramic filter; 4. Online gas chromatograph; 5. Regenerated agent conveying pipe; 6. Fluidized bed regenerator; 7. Second heating furnace; 8. Regenerated agent lifting pipe; 9. Second ceramic filter. DETAILED DESCRIPTION

[0040] The principles and features of the present invention are described below in conjunction with examples. The examples are only used to explain the present invention and are not used to limit the scope of the present invention.

[0041] In a specific embodiment, the dehydrogenation catalyst used is the dehydrogenation catalyst disclosed in Example 2 of the invention patent "A high-strength low-carbon alkane dehydrogenation catalyst and its preparation method" with application number CN201410265574.1, and its particle size range is 20-200 μm, the average particle size is 70 μm, and the density is 1800 kg / m 3 . Example 1

[0042] The in-situ heat-generating particles are prepared in the following steps:

[0043] S1. Weigh 15 g SbCl 3 ·H 2 O, 30 g γ-Al 2 O 3 and 50 g of flux NaCl, mixed evenly and added into a ball mill, grinding at a speed of 100 rpm for 5 h; then the materials were added into a corundum crucible, placed into a muffle furnace for high-temperature melting, heated to 900 °C at a rate of 2 °C / min, kept at this temperature for 6 h, and then naturally cooled to room temperature;

[0044] S2. The product obtained in step S1 is placed in a beaker, 200 g of deionized water is added, stirred, washed, and filtered, and this operation is repeated until the conductivity of the filtrate is less than 80 μS / cm; the filtered cake is placed in a 130°C oven and dried for 12 h; the dried material is manually ground to obtain a powder;

[0045] S3. Add 15 g SbCl to 100 mL deionized water. 3 ·H 2 O, after stirring evenly, add the powder obtained in step S2, and then beat for 5 h to form a thin paste;

[0046] S4. The product obtained in step S3 is spray dried at 200°C by a spray dryer to form microspheres, and then calcined at 600°C for 10 h in an air atmosphere to obtain a granular product. The granular product is sieved, and the particle size distribution is between 20 and 250 μm, with an average particle size of 80 μm; the in-situ heating particles are obtained, and the density is 1805 kg / m 3 . Example 2

[0047] The in-situ heat-generating particles are prepared in the following steps:

[0048] S1. Weigh 10 g FeCl 3 ·H 2 O, 20 g of anatase and 30 g of flux NaCl were mixed evenly and added into a ball mill at a grinding speed of 100 rpm for 4 h; then the materials were added into a corundum crucible and placed into a muffle furnace for high-temperature melting, the temperature was raised to 900 °C at a rate of 2 °C / min, kept at this temperature for 6 h, and then naturally cooled to room temperature;

[0049] S2. The product obtained in step S1 is placed in a beaker, 200 g of deionized water is added, stirred, washed, and filtered, and this operation is repeated until the conductivity of the filtrate is less than 80 μS / cm; the filtered cake is placed in a 130°C oven and dried for 12 h; the dried material is manually ground to obtain a powder;

[0050] S3. Add 20 g FeCl2 into 100 mL deionized water. 3 ·H 2 O, after stirring evenly, add the powder obtained in step S2, and then beat for 4 h to form a thin paste;

[0051] S4. The product obtained in step S3 is spray dried at 200°C by a spray dryer to form microspheres, and then calcined at 600°C for 10 h in an air atmosphere to obtain a granular product. The granular product is sieved, and the particle size distribution is between 20 and 250 μm, with an average particle size of 78 μm; the in-situ heating particles are obtained, and the density is 1802 kg / m 3 . Example 3

[0052] The in-situ heat-generating particles are prepared in the following steps:

[0053] S1. Weigh 15 g MnCl 2 ·H 2 O, 30 g diatomite and 50 g flux KCl, mix well and add into ball mill, grind at 100 rpm for 3 h; then add the materials into corundum crucible, put into muffle furnace for high temperature melting, heat to 1000℃ at a rate of 5℃ / min, keep warm for 8 h, and then cool naturally to room temperature;

[0054] S2. The product obtained in step S1 is placed in a beaker, 200 g of deionized water is added, stirred, washed, and filtered, and this operation is repeated until the conductivity of the filtrate is less than 80 μS / cm; the filtered cake is placed in a 130°C oven and dried for 12 h; the dried material is manually ground to obtain a powder;

[0055] S3. Add 20 g MnCl into 100 mL deionized water. 2 ·H 2 O, after stirring evenly, add the powder obtained in step S2, and then beat for 5 h to form a thin paste;

[0056] S4. The product obtained in step S3 is spray dried at 300°C by a spray dryer to form microspheres, and then calcined at 600°C for 10 h in an air atmosphere to obtain a granular product. The granular product is sieved, and the particle size distribution is between 20 and 250 μm, with an average particle size of 80 μm; the in-situ heating particles are obtained, and the density is 1798 kg / m 3 . Example 4

[0057] The in-situ heat-generating particles are prepared in the following steps:

[0058] S1. Weigh 10 g MgCl 2 6H 2 O, 20 g γ-Al 2 O 3and 40 g of flux KCl, mixed evenly and added into a ball mill, grinding at 120 rpm for 5 h; then the material was added into a corundum crucible, placed into a muffle furnace for high temperature melting, heated to 1000°C at a rate of 2°C / min, kept at this temperature for 6 h, and then naturally cooled to room temperature;

[0059] S2. The product obtained in step S1 is placed in a beaker, 200 g of deionized water is added, stirred, washed, and filtered, and this operation is repeated until the conductivity of the filtrate is less than 80 μS / cm; the filtered cake is placed in a 130°C oven and dried for 12 h; the dried material is manually ground to obtain a powder;

[0060] S3. Add 20 g CdCl in 100 mL deionized water. 2 ·H 2 O, after stirring evenly, heating the powder obtained in step S2 therein, and then beating for 5 h to form a thin paste;

[0061] S4. The product obtained in step S3 is spray dried at 200°C by a spray dryer to form microspheres, and then calcined at 600°C for 10 h in an air atmosphere to obtain a granular product. The granular product is sieved, and the particle size distribution is between 20 and 250 μm, with an average particle size of 78 μm; the in-situ heating particles are obtained, and the density is 1797 kg / m 3 . Comparative Example 1

[0062] The in-situ heat-generating particles are prepared in the following steps:

[0063] S1. Weigh 15 g SbCl 3 ·H 2 O, 30 g γ-Al 2 O 3 and 50 g of flux NaCl, mixed evenly and added into a ball mill, grinding at a speed of 100 rpm for 5 h; then the materials were added into a corundum crucible, placed into a muffle furnace for high-temperature melting, heated to 900 °C at a rate of 2 °C / min, kept at this temperature for 6 h, and then naturally cooled to room temperature;

[0064] S2. Place the product obtained in step S1 in a beaker, add 200 g of deionized water, stir and wash, and then filter. Repeat this operation until the conductivity of the filtrate is less than 80 μS / cm; place the filtered filter cake in a 130°C oven and dry it for 12 h; press the dried material into tablets, crush it, and sieve it to obtain particles with a particle size distribution between 20 and 250 μm. Comparative Example 2

[0065] S1. Add 15 g SbCl to 100 mL deionized water.3 ·H 2 O, stir evenly, add 30g γ-Al 2 O 3 , then beat for 5 hours to make a thin paste;

[0066] S2. The product obtained in step S3 is spray dried at 200° C. by a spray dryer to form microspheres, and then calcined at 600° C. for 10 h in an air atmosphere to obtain a granular product. The granular product is sieved, and the particle size distribution thereof is between 20 and 250 μm.

[0067] Application Example 1: Application of in-situ heat-generating particles in fixed fluidized bed propane dehydrogenation

[0068] The particle samples prepared in the above embodiments or comparative examples were physically mixed with a dehydrogenation catalyst at a mass ratio of 1:10, and loaded into a fixed fluidized bed reactor with a height of 1000 mm and an inner diameter of 32 mm to evaluate its heat generation performance and reaction performance improvement effect.

[0069] Under normal pressure, the particle samples prepared in each embodiment or comparative example were heated to 600°C under the action of nitrogen fluidization gas. After stable fluidization for 2 h, the nitrogen was switched to propane gas and fed at a rate of 0.15 kg / h. The bed temperature was tested by a device thermocouple, the reactor outlet composition was tested by gas chromatography, and the propane conversion rate and propylene selectivity were calculated. The results are shown in Table 1.

[0070] Table 1 Fixed fluidized bed dehydrogenation reaction results

[0071] Serial number Bed temperature / ℃ Propane conversion rate / % Propylene yield / % Example 1 598 48.6 41.5 Example 2 597 47.3 40.7 Example 3 596 45.7 39.0 Example 4 601 49.9 42.1 Comparative Example 1 587 39.5 33.1 Comparative Example 2 583 36.4 31.0

[0072] It can be seen from the data in Table 1 that using the heat-generating particles prepared by the present invention, the bed temperature in the fluidized bed reactor is higher and the propane conversion rate is higher, and the propylene yield is increased. That is, the heat-generating particles proposed in the present invention can provide heat in situ, maintain a constant bed temperature, and improve the dehydrogenation reaction effect of low-carbon alkanes.

[0073] Application Example 2: Application of in-situ heat-generating particles in circulating fluidized bed propane dehydrogenation

[0074] The in-situ heat-generating particles (Sb 2 O 3 / γ-Al 2 O 3 ) is mixed with a dehydrogenation catalyst in a fluidized bed propane dehydrogenation.

[0075] Reference Figure 1As shown: the heating particles and the dehydrogenation catalyst are mixed and loaded into the fluidized bed regenerator 6, and the device is turned on for fluidization; after the particles are circulated and fluidized in the entire device and stabilized, the raw alkane is introduced. After the raw alkane is preheated by the first heating furnace 1, it enters the device through the gas distributor at the bottom of the fluidized bed reactor 2, countercurrently contacts and reacts with the solid catalyst particles flowing from top to bottom, and the gas after the reaction is discharged after gas-solid separation through the first ceramic filter 3 at the top of the reactor, and enters the online gas chromatograph 4 for analysis; the carbon deposited catalyst participating in the reaction is discharged from the center port at the bottom of the fluidized bed reactor 2, and is lifted to the fluidized bed regenerator 6 through the regenerated agent conveying pipe 5, and then countercurrently contacts with the air preheated by the second heating furnace 7 and undergoes a charring reaction to restore activity, and then is discharged from the center outlet at the bottom of the fluidized bed regenerator 6, and is conveyed to the upper part of the fluidized bed reactor 2 by the regeneration agent lifting pipe 8. The regenerated flue gas is separated from the device after gas-solid separation through the second ceramic filter 9 at the top of the fluidized bed regenerator 6. This cycle is repeated to perform the continuous reaction and regeneration operation of low-carbon alkane dehydrogenation.

[0076] Specifically, the mass ratio of in-situ heat-generating particles to dehydrogenation catalyst particles is 1:2, and the mass ratio of propane feed amount to total particle circulation amount is 1:3; the raw material propane feed amount is 2 kg / h, and the raw material preheating temperature is 500°C; the air feed amount during the regeneration process is 3 kg / h, and the air preheating temperature is 600°C, and no other fuel is added during regeneration.

[0077] Application Example 3: Application of in-situ heat-generating particles in circulating fluidized bed propane dehydrogenation

[0078] The in-situ heat-generating particles (Sb 2 O 3 / γ-Al 2 O 3 ) is mixed with a dehydrogenation catalyst in a fluidized bed propane dehydrogenation.

[0079] Referring to Application Example 2, the difference from Application Example 2 is that the mass ratio of propane feed amount to total particle circulation amount is 1:6. Other technical features are the same as those of Application Example 2.

[0080] Application Example 4: Application of in-situ heat-generating particles in circulating fluidized bed isobutane dehydrogenation

[0081] The in-situ heat-generating particles (Sb 2 O 3 / γ-Al 2 O 3 ) is mixed with a dehydrogenation catalyst in a fluidized bed isobutane dehydrogenation.

[0082] Referring to Application Example 2, the difference from Application Example 2 is that the mass ratio of the in-situ heat generating particles to the dehydrogenation catalyst particles is 1:3; the corresponding description of propane in Application Example 2 is replaced by isobutane. Other technical features are the same as those of Application Example 2.

[0083] Application Example 5: Application of in-situ heat-generating particles in circulating fluidized bed isobutane dehydrogenation

[0084] The in-situ heat-generating particles (Sb 2 O 3 / γ-Al 2 O 3 ) is mixed with a dehydrogenation catalyst in a fluidized bed isobutane dehydrogenation.

[0085] Referring to Application Example 4, the difference from Application Example 4 is that the mass ratio of the in-situ heat generating particles to the dehydrogenation catalyst particles is 1:4. Other technical features are the same as those of Application Example 2.

[0086] Application Comparative Example 1

[0087] Inert alumina particles with a particle size range of 20-250 μm are mixed with a dehydrogenation catalyst in a fluidized bed propane dehydrogenation.

[0088] Referring to Application Example 2, the difference from Application Example 2 is that the in-situ heat generating particles are replaced with inert alumina particles in equal amounts, and the supplementary fuel during regeneration is natural gas. Other technical features are the same as those of Application Example 2.

[0089] Application Comparative Example 2

[0090] Inert alumina particles with a particle size range of 20 to 250 μm are mixed with a dehydrogenation catalyst in a fluidized bed isobutane dehydrogenation.

[0091] Referring to Application Example 4, the difference from Application Example 4 is that the in-situ heat generating particles are replaced with inert alumina particles in equal amounts, and the supplementary fuel during regeneration is natural gas. Other technical features are the same as those of Application Example 4.

[0092] The product distribution and product conversion rate of Application Example 2, Application Example 3 and Application Comparative Example 1 on the circulating fluidized bed continuous reaction regeneration device are shown in Table 2, and the product distribution and product conversion rate of Application Example 4, Application Example 5 and Application Comparative Example 2 on the circulating fluidized bed continuous reaction regeneration device are shown in Table 3.

[0093] Table 2 Results of Application Example 2, Application Example 3 and Application Comparative Example 1

[0094] Serial number Application Example 2 Application Example 3 Application Comparative Example 1 Bed temperature / ℃ 598 603 601 Hydrogen yield / % 1.02 1.11 1.65 Methane yield / % 1.59 1.64 1.97 Ethane yield / % 2.25 2.31 2.11 Ethylene yield / % 1.02 1.16 1.01 Propylene yield / % 40.90 41.21 31.10 Coke yield / % 0.73 0.78 0.95 Propane conversion rate / % 47.89 48.88 43.21

[0095] Table 3 Results of Application Example 4, Application Example 5 and Application Comparative Example 2

[0096] Serial number Application Example 4 Application Example 5 Application Comparative Example 2 Bed temperature / ℃ 578 573 575 Hydrogen yield / % 1.02 0.87 1.65 Methane yield / % 1.32 1.08 2.19 Ethane yield / % 0.09 0.08 0.21 Ethylene yield / % 0.05 0.04 0.12 Propane yield / % 0.76 0.71 1.33 Propylene yield / % 1.01 0.88 1.38 Isobutylene yield / % 44.19 39.78 34.21 Coke yield / % 0.72 0.68 0.91 Isobutane conversion rate / % 49.62 44.30 42.18

[0097] It can be seen from the data in Tables 2 and 3 that when the heat-generating particles are used, the bed temperature is higher and the propane conversion rate is higher, and the propylene yield is increased. That is, the heat required for the dehydrogenation process can be provided in situ by mixing the heat-generating particles proposed in the present invention, thereby maintaining a constant bed temperature and improving the dehydrogenation reaction effect of light alkanes.

[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing in-situ heat-generating particles, characterized in that: The steps include: S1. The metal salt, the carrier and the flux are mixed to obtain a mixture; the mixture is subjected to a high temperature melting treatment and cooled; The metal salt is at least one of antimony salt, iron salt, magnesium salt, manganese salt and cadmium salt; The carrier is at least one of alumina, diatomaceous earth and anatase; The flux is sodium chloride and / or potassium chloride; The mass ratio of metal salt to carrier is 1:(1~10); The mass ratio of metal salt to co-solvent is 1:(1~10); S2. The product obtained in step S1 is ground into powder; Before grinding, the product obtained in step S1 is washed and dried in advance; it is washed with deionized water until the conductivity of the filtrate is less than 80 μS / cm; S3. The product obtained in step S2 is added to an aqueous solution of a metal salt for impregnation; The metal salt is at least one of antimony salt, iron salt, magnesium salt, manganese salt and cadmium salt; S4. The product obtained in step S3 is dried and formed and then calcined; The calcination conditions are: calcination temperature 500~800℃, heating rate 2~10℃ / min, holding time 5~10 h; calcination in air atmosphere.

2. The preparation method according to claim 1, characterized in that: In step S1 and step S3: the metal salt is a metal halide and / or a nitrate.

3. The preparation method according to claim 1, characterized in that: In step S4: the drying and forming is spray drying and forming.

4. The preparation method according to claim 3, characterized in that: In step S3: the pulp is evenly beaten during the dipping process.

5. An in-situ heat-generating particle obtained by the preparation method according to any one of claims 1 to 4.

6. Use of the in-situ heat-generating particles as claimed in claim 5 in the dehydrogenation of light alkanes in a fluidized bed.

7. The use according to claim 6, characterized in that: The in-situ heat-generating particles and the dehydrogenation catalyst are mixed and used in the dehydrogenation of low-carbon alkanes in a fluidized bed; the fluidized bed is a fixed fluidized bed or a circulating fluidized bed.

8. The use according to claim 7, characterized in that: The dehydrogenation catalyst is a microspherical particle catalyst based on chromium or tungsten.

Images