Methods to improve space utilization in alkane dehydrogenation reactors and methods for producing low-carbon olefins from alkane dehydrogenation.

Abstract

This invention proposes a method to improve the space utilization of alkane dehydrogenation reactors, primarily addressing the problem in existing propane dehydrogenation reactors where the mixing of catalyst with a large amount of heat storage particles results in a small catalyst volume in the bed and low reactor space utilization. The method involves incorporating a core-shell structured heat storage material into the reactor catalyst bed. This core-shell structured heat storage material consists of a high-temperature resistant outer shell and a metal alloy core, with a volume ratio of core-shell structured heat storage material to catalyst of (0.05–0.3):1. Using this invention, the space utilization of the alkane dehydrogenation reactor is increased by more than 25%, the catalyst bed volume is significantly increased, and the equipment size can be significantly reduced, thus increasing production capacity. Simultaneously, by better matching the catalyst bed temperature distribution with the endothermic reaction process, the conversion rate and selectivity of the reaction are significantly improved, demonstrating significant technical advantages and promising application prospects.

Description

Technical Field

[0001] This invention belongs to the field of petrochemical technology, specifically relating to a method for improving the space utilization of an alkane dehydrogenation reactor and a method for producing low-carbon olefins from alkane dehydrogenation. Background Technology

[0002] Low-carbon olefins are essential organic raw materials with high demand and wide applications in the petrochemical industry. For example, propylene is a crucial basic petrochemical raw material with high demand and wide applications, second only to ethylene in total production. It is widely used in the production of polypropylene, acrylonitrile, propylene oxide, cumene / phenol / acetone / bisphenol A, acrylic acid and esters, epichlorohydrin, and other chemical products. Butene is also a widely used low-carbon olefin, used in the production of high-octane gasoline components, maleic anhydride, sec-butanol, heptene, polybutene, acetic anhydride, and other chemical products.

[0003] With the increasing demand for low-carbon olefins, especially propylene, in recent years, the production of low-carbon olefins by traditional methods such as catalytic cracking and steam cracking byproducts can no longer meet the supply. Therefore, technologies that expand the sources of low-carbon olefins, such as dehydrogenation of low-carbon alkanes to produce olefins, have been widely used.

[0004] Taking propylene as an example, the mainstream propane dehydrogenation processes for propylene production currently include UOP's Oleflex process and ABB Lummus's Catofin process. Among them, the Catofin process has advantages such as high conversion rate, good selectivity, high online rate, and strong feedstock adaptability, thus attracting increasing attention and widespread application. In the Catofin process, the propane dehydrogenation reaction for propylene is largely endothermic, causing a decrease in catalyst bed temperature. Simultaneously, the coking generated by the reaction also leads to a rapid decline in catalyst activity. Therefore, to ensure that the catalyst activity is within the optimal range, it needs to be regenerated periodically, and the catalyst bed needs to be reheated to accumulate heat in preparation for subsequent reactions. Propane dehydrogenation reactions are typically operated under high temperature, negative pressure, or low pressure conditions, and temperature has a significant impact on the reaction. Excessively high reaction temperatures can lead to side reactions such as propane cracking, further generating coking that reduces catalyst activity and results in decreased selectivity. On the other hand, excessively low reaction temperatures can cause a rapid decrease in conversion rate. When the catalyst bed temperature distribution is uneven, local hot spots or cold spots can appear, causing a decrease in conversion rate or selectivity. Therefore, heat storage and temperature control of the catalyst bed are critical issues in propane dehydrogenation.

[0005] In the dehydrogenation reaction, almost all the heat absorbed by the dehydrogenation of low-carbon alkanes comes from the heat storage of the catalyst bed. Therefore, the heat storage capacity of the bed determines the duration of the dehydrogenation reaction. Due to the large-scale cracking of low-carbon alkanes at temperatures above 650℃, the maximum temperature of the catalyst bed is limited. To ensure that the catalyst bed has sufficient heat storage capacity to support the required dehydrogenation reaction time, it is often necessary to supplement a large amount of heat storage material.

[0006] The commonly used heat storage material is inert alumina (Al₂O₃). The ratio of inert alumina to catalyst varies depending on the feedstock for the dehydrogenation reaction. For propane dehydrogenation, inert alumina can occupy about 50% of the entire catalyst bed volume; while for isobutane dehydrogenation, it can occupy about 30%. Therefore, the actual catalyst used for the dehydrogenation reaction only accounts for about 50-70% of the total catalyst bed volume. A significant amount of reactor space is occupied by the heat storage inert alumina, resulting in low space utilization in the alkane dehydrogenation reactor, affecting the plant's production capacity, and necessitating an increase in equipment size.

[0007] Recent technical reports have disclosed methods for supplementing the heat required for the dehydrogenation reaction stage by increasing the heating of the catalyst bed in the reactor. For example, CN104072325A discloses a method to improve the performance of low-carbon alkane dehydrogenation reactions. This method uses a fixed-bed reactor with built-in electric heating tubes to provide heat to the catalyst bed during dehydrogenation, thereby reducing the temperature drop caused by endothermic reaction. Furthermore, by reducing the heat load of the electric heater before the reactor, the thermal cracking of low-carbon alkanes is reduced, ultimately improving the performance of the low-carbon alkane dehydrogenation reaction.

[0008] CN113149802A discloses an improved method and apparatus for dehydrogenation of low-carbon alkanes to produce olefins in a fixed bed. It employs alumina additives loaded with Group IB and IIA elements, and a bed-embedded heating pipe with gas, molten salt, and caustic alkali high-temperature heat medium to achieve heat balance and temperature uniformity in the reaction bed during the conversion process. This reduces the severity of the reaction process, temperature difference, thermal cracking, and coking side reactions, and improves the conversion activity, selectivity, single-pass reaction time, operational stability, and maintainability.

[0009] However, these methods have the following problems: on the one hand, it is usually difficult to ensure that the surface temperature of the electric heating tube or the built-in heating tube is uniform, which increases the possibility of local hot spots causing cracking reactions; on the other hand, the introduction of metal components will also exacerbate the cracking of low-carbon alkanes and affect the selectivity of the reaction.

[0010] Other technical reports have also disclosed the addition of exothermic materials to the catalyst bed. For example, CN106029612A discloses an improved alkane endothermic dehydrogenation process utilizing exothermic materials. In addition to using CATOFIN@300 catalyst and inert alumina, the process also uses HGM exothermic materials (copper, manganese, and other metal elements loaded on alumina). This includes reacting hydrocarbons with a multi-component catalyst bed and regenerating the catalyst bed using air. The air and hydrocarbons used in the regeneration step are at a low air / hydrocarbon ratio and near-atmospheric pressure, which improves process efficiency. The added exothermic material mainly provides heat to reduce air consumption during regeneration and does not increase the bed's heat storage capacity; a large amount of inert alumina still needs to be added to the catalyst bed.

[0011] CN107074683A discloses a method for catalytic dehydrogenation of alkanes to olefins using a Cr2O3 catalyst. CuO, a heat-releasing material, is added to the catalyst bed, and CO is introduced as a reducing gas to reduce the catalyst in parallel with the dehydrogenation process. Heat is released as CO reacts with CuO to form Cu and CO2. However, this method introduces both heat and components such as CO and CO2, causing a decrease in the partial pressure of the reactant gases and affecting the reaction conversion rate.

[0012] CN108300430B discloses an exothermic catalytic agent for alkane dehydrogenation, its preparation method, and its application method. This agent stores heat during the catalyst regeneration stage and releases heat during the catalytic reaction, thereby suppressing the decrease in reaction temperature. The heat sources in the agent are mainly: the exothermic reaction of CuO with H2 to generate water, the heat-generating material absorbing water and releasing heat, and the agent itself storing some heat as a heat medium. However, this method requires the consumption of additional hydrogen, and the generated water accelerates the formation of α-chromium-aluminum in the catalyst, leading to a significant decrease in reaction conversion rate.

[0013] Currently, the low space utilization rate of the reactor caused by the heat storage problem of the catalyst bed in the dehydrogenation reaction of low-carbon alkane has been widely recognized in the industry. Many scholars have also proposed solutions to the above problems by using various means or combinations thereof, such as built-in heating tubes, heat-generating materials, and exothermic agents. However, due to various reasons, these solutions will have certain adverse effects on the existing process and require further improvement. Summary of the Invention

[0014] To address the aforementioned problems in the prior art, this invention proposes a method for improving the space utilization of an alkane dehydrogenation reactor and a method for producing low-carbon olefins from alkane dehydrogenation.

[0015] In a first aspect, the present invention provides a method for improving the space utilization rate of an alkane dehydrogenation reactor, comprising adding a heat storage material to the catalyst bed of the reactor, the heat storage material comprising a core-shell structure heat storage material and Al2O3 ceramic balls; the core-shell structure heat storage material is composed of a high-temperature resistant outer shell and a metal alloy core; the volume ratio of the Al2O3 ceramic balls to the core-shell structure heat storage material is (0.1-1):1, preferably (0.2-0.5):1; the volume ratio of the core-shell structure heat storage material to the catalyst is (0.05-0.3):1, preferably (0.1-0.2):1.

[0016] As a specific embodiment of the present invention, the high-temperature resistant outer shell is an inert metal oxide, preferably selected from aluminum oxide, α-alumina, γ-alumina, silicon oxide, aluminum oxide and silicon oxide.

[0017] In a specific embodiment of the present invention, the metal alloy core is an aluminum alloy, preferably selected from aluminum-magnesium alloy or cast aluminum alloy; the melting point of the metal alloy core is 500-650°C, preferably 560-620°C.

[0018] As a specific embodiment of the present invention, the particle size of the core-shell structure heat storage material is 3-50 mm, preferably 10-20 mm; wherein, the particle size of the metal alloy core is 2-49 mm, and the thickness of the high-temperature resistant shell is 10-500 μm.

[0019] As a specific embodiment of the present invention, the preparation method of the core-shell structured thermal storage material includes the following steps:

[0020] S1: The alloy core material is processed into small spheres of the desired particle size by mechanical processing to obtain the metal alloy core;

[0021] S2: The surface of the metal alloy core obtained in step S1 is subjected to one or more thermal sprayings to obtain the high-temperature resistant shell and the core-shell structure heat storage material is obtained.

[0022] Optionally, S3: The core-shell structured heat storage material obtained in step S2 is immersed in SiO2 sol for 1 minute, and the immersed material is dried to obtain the core-shell structured heat storage material.

[0023] As a specific embodiment of the present invention, the heat storage material and the catalyst are distributed in segments in the catalyst bed;

[0024] Preferably, the catalyst bed is divided into three or more sections from top to bottom, wherein the volume ratio of the upper section to the lower section in any two adjacent sections is (0.1-10):1;

[0025] Each section consists of a mixture of catalyst and / or heat storage material. The ratio of heat storage material to catalyst varies in each section. The volume ratio of heat storage material to catalyst in each section is (0.01-3):1, preferably (0.05-0.5):1.

[0026] Specifically, arranging the heat storage material closer to the middle and upper part is a better choice, as it can improve both selectivity and conversion rate. Arranging it closer to the outlet can significantly improve the conversion rate, while the selectivity remains relatively unchanged.

[0027] The core-shell structured heat storage material provided by this invention utilizes the phase change heat of a metal alloy to achieve heat storage. Specifically, in the dehydrogenation process of low-carbon alkanes, the core-shell structured heat storage material and catalyst in the reactor bed are heated to 600-650℃ using regenerated air. During the regeneration process, the metal alloy core absorbs heat and melts into a liquid phase, thereby achieving a large amount of heat storage. In the dehydrogenation reaction stage, the reaction temperature is 560-620℃. The metal alloy, melted into a liquid phase, releases a large amount of heat and becomes a solid phase to maintain the temperature of the catalyst bed. The metal alloy core in the core-shell structured heat storage material provided by this invention is an aluminum alloy, whose phase change heat during melting is approximately 250-550 kJ / kg, while the heat capacity of inert alumina is approximately 0.7-0.9 kJ / kg℃. In the same dehydrogenation reaction process, the core-shell structured heat storage material provided by this invention can provide 6-10 times the heat of the same mass of inert alumina. Therefore, compared to the inert alumina heat storage materials used in existing technologies, the actual catalyst used for the dehydrogenation reaction in the catalyst bed only accounts for about 50-70% of the total catalyst bed volume. However, by using the core-shell structure heat storage material provided by this invention, the actual catalyst used for the dehydrogenation reaction in the catalyst bed can account for 71-95% of the total catalyst bed volume, and the space utilization rate of the alkane dehydrogenation reactor is improved by more than 25%.

[0028] Meanwhile, considering the different heat absorption rates of catalyst beds at different heights during the dehydrogenation reaction, the core-shell structure heat storage material and catalyst can be unevenly distributed in the catalyst bed. Preferably, the catalyst bed is divided into three or more parts from top to bottom, wherein the volume ratio of the upper part to the lower part in any two adjacent parts is (0.1-10):1. Each part may be composed of a catalyst or a mixture of catalyst and core-shell structure heat storage material, with different proportions of core-shell structure heat storage material and catalyst in each part, and the volume ratio of heat storage material to catalyst is (0.01-3):1, preferably (0.05-0.5):1. To more accurately match the different heat absorption rates of catalyst beds at different heights during the dehydrogenation reaction, Al2O3 ceramic balls are also added to the catalyst bed, and the volume ratio of the Al2O3 ceramic balls to the core-shell structure heat storage material is (0.1-1):1, preferably (0.2-0.5):1.

[0029] As a specific embodiment of the present invention, the catalyst is a catalyst containing at least one metal selected from Cr or Pt.

[0030] Secondly, the present invention provides a method for producing low-carbon olefins by dehydrogenation of alkanes. In the dehydrogenation reaction of one or more alkanes selected from propane, n-butane, and isobutane, the method for improving the space utilization rate of the alkane dehydrogenation reactor described in the first aspect is used to carry out the dehydrogenation reaction to produce low-carbon olefins.

[0031] In a specific embodiment of the present invention, the dehydrogenation reaction temperature is 550-650℃, the pressure is 20-100kPa, and the mass hourly space velocity of the reaction gas is 0.4-2hr. -1 .

[0032] As a specific embodiment of the present invention, the method includes producing low-carbon olefins by alternating processes of reaction, purging, regeneration, evacuation, and reduction using 3-10 parallel alkane dehydrogenation reactors.

[0033] In a specific embodiment of the present invention, the regeneration process uses air regeneration, and the regeneration air temperature is 600-700°C.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] 1. The core-shell structure heat storage material of the present invention adopts phase change heat storage, which has a higher heat storage capacity, which is 6 to 10 times that of the inert alumina used in the prior art.

[0036] 2. The method of the present invention for improving the space utilization rate of alkane dehydrogenation reactor has a low core-shell structure heat storage material loading ratio and a significantly increased catalyst bed volume, thereby improving the space utilization rate of alkane dehydrogenation reactor by more than 25%, which can significantly reduce the reactor equipment size and increase production capacity.

[0037] 3. The method of the present invention for improving the space utilization of the alkane dehydrogenation reactor does not introduce additional substances and is inert to the reaction process.

[0038] 4. The method of the present invention for improving the space utilization of alkane dehydrogenation reactor has a higher degree of matching between the temperature distribution of the catalyst bed and the endothermic degree of the dehydrogenation reaction process, and the reaction is controlled within the range of optimal catalyst activity, resulting in a significant improvement in reaction conversion rate and selectivity. Attached Figure Description

[0039] Figure 1 A schematic diagram of a catalyst bed for improving space utilization in an alkane dehydrogenation reactor, provided by the present invention.

[0040] Figure 2 A schematic diagram of the core-shell structured heat storage material provided by the present invention;

[0041] Figure 3 A schematic diagram of a catalyst bed provided for existing technology;

[0042] Figure 4 A schematic diagram of a preferred embodiment of the catalyst bed provided by the present invention;

[0043] Figure 5 A schematic diagram of another preferred form of catalyst bed provided by the present invention.

[0044] Among them, 1-catalyst bed, 1a-first part of catalyst bed, 1b-second part of catalyst bed, 1c-third part of catalyst bed; 2-catalyst; 3-core-shell structured heat storage material, 3a-high temperature resistant shell, 3b-metal alloy core; 4-alumina ceramic ball. Detailed Implementation

[0045] The present invention will be further described below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0046] The catalyst information used in the various embodiments of this invention is as follows:

[0047] Cr-containing metal catalyst: Cr metal catalyst supported on alumina support (Cr content 10wt%), with a particle size of 3mm;

[0048] Pt-containing catalyst: Pt metal supported on an alumina support (Pt content 0.3wt%), with a particle size of 10 mm.

[0049] The Al2O3 ceramic balls used in the various embodiments of the present invention contain more than 99% Al2O3.

[0050] Example 1

[0051] This embodiment provides a core-shell structured thermal storage material and its preparation method, with specific details as follows:

[0052] S1: The alloy core material is processed into small spheres of the desired particle size by mechanical processing to obtain the metal alloy core;

[0053] S2: The surface of the metal alloy core obtained in step S1 is subjected to one or more thermal sprayings to obtain the high-temperature resistant shell and the core-shell structure heat storage material is obtained.

[0054] S3: Optionally, the core-shell structured heat storage material obtained in step S2 is immersed in SiO2 sol for 1 minute, and the immersed material is dried to obtain the core-shell structured heat storage material.

[0055] The high-temperature resistant outer shell of the core-shell structure heat storage material obtained in Example 1 is made of alumina, and the alloy material of the core is aluminum-magnesium alloy. The melting point of the metal alloy core is 580℃ and the particle size is 10mm.

[0056] Examples 2-6

[0057] The core-shell structured thermal storage materials obtained according to the preparation method provided in Example 1 in Examples 2-6 are shown in Table 1:

[0058] Table 1. Core-shell structured thermal storage materials prepared in Examples 1-6

[0059]

[0060] Example 7

[0061] In a Cr-containing catalyst bed, a core-shell structured heat storage material prepared in Example 1 was added, with a volume ratio of core-shell structured heat storage material to catalyst of 0.1:1. The core-shell structured heat storage material and catalyst in the catalyst bed were uniformly mixed, such as... Figure 1 As shown, the catalyst occupies 91% of the catalyst bed volume.

[0062] The propane dehydrogenation to propylene reaction was carried out in a reactor packed with the aforementioned catalyst bed. The dehydrogenation reaction employed a reaction-regeneration cycle: reaction time 10 minutes, nitrogen purging for 1 minute, regeneration time 10 minutes, nitrogen purging for 1 minute, and evacuation for 1 minute. The reaction temperature was 600℃, the pressure was 50 kPa absolute, and the propane space velocity was 0.6 hr⁻¹. -1 The regenerated air temperature was 650℃. The reaction results showed a propane conversion rate of 47.2% and a propylene selectivity of 90.8%.

[0063] Example 8

[0064] In a Cr-containing catalyst bed, a core-shell structured heat storage material prepared in Example 1 was added, with a volume ratio of core-shell structured heat storage material to catalyst of 0.2:1. The core-shell structured heat storage material and catalyst were uniformly mixed in the catalyst bed. The catalyst occupied 83% of the bed volume.

[0065] The propane dehydrogenation to propylene reaction was carried out in a reactor packed with the aforementioned catalyst bed. The dehydrogenation reaction employed a reaction-regeneration cycle: reaction time 10 minutes, nitrogen purging for 1 minute, regeneration time 10 minutes, nitrogen purging for 1 minute, and evacuation for 1 minute. The reaction temperature was 600℃, the pressure was 50 kPa absolute, and the propane space velocity was 0.6 hr⁻¹. -1 The regenerated air temperature was 650℃. The reaction results showed a propane conversion rate of 50.2% and a propylene selectivity of 90.6%.

[0066] Example 9

[0067] In a Cr-containing catalyst bed, a core-shell structured heat storage material prepared in Example 1 was added, with a volume ratio of core-shell structured heat storage material to catalyst of 0.3:1. The core-shell structured heat storage material and catalyst were uniformly mixed in the catalyst bed. The catalyst accounted for 77% of the bed volume.

[0068] The propane dehydrogenation to propylene reaction was carried out in a reactor packed with the aforementioned catalyst bed. The dehydrogenation reaction employed a reaction-regeneration cycle: reaction time 10 minutes, nitrogen purging for 1 minute, regeneration time 10 minutes, nitrogen purging for 1 minute, and evacuation for 1 minute. The reaction temperature was 600℃, the pressure was 50 kPa absolute, and the propane space velocity was 0.6 hr⁻¹. -1 The regenerated air temperature was 650℃. The reaction results showed a propane conversion rate of 51.4% and a propylene selectivity of 88.5%.

[0069] Example 10

[0070] In a Cr-containing catalyst bed, a core-shell structured heat storage material prepared in Example 1 was added, with a volume ratio of core-shell structured heat storage material to catalyst of 0.05:1. The core-shell structured heat storage material and catalyst were uniformly mixed in the catalyst bed. The catalyst occupied 95% of the bed volume.

[0071] The propane dehydrogenation to propylene reaction was carried out in a reactor packed with the aforementioned catalyst bed. The dehydrogenation reaction employed a reaction-regeneration cycle: reaction time 10 minutes, nitrogen purging for 1 minute, regeneration time 10 minutes, nitrogen purging for 1 minute, and evacuation for 1 minute. The reaction temperature was 600℃, the pressure was absolute 80 kPa, and the propane space velocity was 0.4 hr⁻¹. -1 The regenerated air temperature was 600℃. The reaction results showed a propane conversion rate of 46.1% and a propylene selectivity of 92.0%.

[0072] Example 11

[0073] The core-shell structured heat storage material prepared in Example 1 was added to the catalyst bed containing Cr metal, with a volume ratio of core-shell structured heat storage material to catalyst of 0.1:1.

[0074] In the catalyst bed, the core-shell structured heat storage material and the catalyst are non-uniformly mixed. The catalyst bed is as follows: Figure 4As shown, the bed is divided into three parts from top to bottom: Part 1, Part 2, and Part 3. The volume ratio of Part 1 to Part 2 is 0.5, and the volume ratio of Part 2 to Part 3 is 0.8. Parts 1 and 2 consist of a catalyst and a core-shell structured heat storage material. In Part 1, the volume ratio of catalyst to core-shell structured heat storage material is 0.05:1, and in Part 2, the volume ratio is 0.25:1. Part 3 consists of the catalyst itself. In the catalyst bed, the catalyst occupies 91% of the bed volume.

[0075] The propane dehydrogenation to propylene reaction was carried out in a reactor packed with the aforementioned catalyst bed. The dehydrogenation reaction employed a reaction-regeneration cycle: reaction time 10 minutes, nitrogen purging for 1 minute, regeneration time 10 minutes, nitrogen purging for 1 minute, and evacuation for 1 minute. The reaction temperature was 600℃, the pressure was 50 kPa absolute, and the propane space velocity was 0.6 hr⁻¹. -1 The regenerated air temperature was 650℃. The reaction results showed a propane conversion rate of 48.5% and a propylene selectivity of 91.6%.

[0076] Example 12

[0077] The core-shell structured heat storage material prepared in Example 1 was added to a catalyst bed containing Cr metal, with a volume ratio of core-shell structured heat storage material to catalyst of 0.2:1.

[0078] The core-shell structured heat storage material and catalyst in the catalyst bed are non-uniformly mixed. The catalyst bed is divided into three parts from top to bottom: Part 1, Part 2, and Part 3. The volume ratio of Part 1 to Part 2 is 0.1, and the volume ratio of Part 2 to Part 3 is 2. Parts 1 and 2 consist of catalyst and core-shell structured heat storage material, with a volume ratio of catalyst to core-shell structured heat storage material of 0.2:1 in Part 1 and 0.3:1 in Part 2. Part 3 consists of catalyst. The catalyst accounts for 83% of the volume of the catalyst bed.

[0079] The propane dehydrogenation to propylene reaction was carried out in a reactor packed with the aforementioned catalyst bed. The dehydrogenation reaction employed a reaction-regeneration cycle: reaction time 10 minutes, nitrogen purging for 1 minute, regeneration time 10 minutes, nitrogen purging for 1 minute, and evacuation for 1 minute. The reaction temperature was 600℃, the pressure was 50 kPa absolute, and the propane space velocity was 0.6 hr⁻¹. -1 The regenerated air temperature was 650℃. The reaction results showed a propane conversion rate of 51.8% and a propylene selectivity of 91.1%.

[0080] Example 13

[0081] The core-shell structured heat storage material prepared in Example 1 was added to a catalyst bed containing Cr metal, with a volume ratio of core-shell structured heat storage material to catalyst of 0.3:1.

[0082] The core-shell structured heat storage material and catalyst in the catalyst bed are non-uniformly mixed. The catalyst bed is divided into three parts from top to bottom: Part 1, Part 2, and Part 3. The volume ratio of Part 1 to Part 2 is 0.01, and the volume ratio of Part 2 to Part 3 is 10. Part 1 consists of the catalyst. Parts 2 and 3 consist of the catalyst and the core-shell structured heat storage material. In Part 2, the volume ratio of catalyst to core-shell structured heat storage material is 0.3:1, and in Part 3, the volume ratio is 0.33:1. The catalyst accounts for 77% of the volume of the catalyst bed.

[0083] The propane dehydrogenation to propylene reaction was carried out in a reactor packed with the aforementioned catalyst bed. The dehydrogenation reaction employed a reaction-regeneration cycle: reaction time 10 minutes, nitrogen purging for 1 minute, regeneration time 10 minutes, nitrogen purging for 1 minute, and evacuation for 1 minute. The reaction temperature was 600℃, the pressure was 50 kPa absolute, and the propane space velocity was 0.6 hr⁻¹. -1 The regenerated air temperature was 650℃. The reaction results showed a propane conversion rate of 55.2% and a propylene selectivity of 87.5%.

[0084] Example 14

[0085] The core-shell structured heat storage material prepared in Example 2 was added to the catalyst bed containing Cr metal, with a volume ratio of core-shell structured heat storage material to catalyst of 0.05:1.

[0086] The core-shell structured heat storage material and catalyst in the catalyst bed are non-uniformly mixed. The catalyst bed is divided into three parts from top to bottom: Part 1, Part 2, and Part 3. The volume ratio of Part 1 to Part 2 is 0.5:1, and the volume ratio of Part 2 to Part 3 is 0.8:1. Parts 1 and 2 consist of catalyst and core-shell structured heat storage material, with the volume ratio of catalyst to core-shell structured heat storage material being 0.015:1 in Part 1 and 0.13:1 in Part 2. Part 3 consists of catalyst. The catalyst occupies 95% of the catalyst bed volume.

[0087] The dehydrogenation of n-butane to n-butene was carried out in a reactor packed with the aforementioned catalyst bed. The dehydrogenation reaction employed a reaction-regeneration cycle: reaction time 10 minutes, nitrogen purging for 1 minute, regeneration time 10 minutes, nitrogen purging for 1 minute, and evacuation for 1 minute. The reaction temperature was 600℃, the pressure was absolute 80 kPa, and the propane space velocity was 0.4 hr⁻¹. -1The regenerated air temperature was 600℃. The reaction results showed a butane conversion rate of 47.1% and a butene selectivity of 86.2%.

[0088] Example 15

[0089] The core-shell structured heat storage material prepared in Example 1 was added to a catalyst bed containing Cr metal, with a volume ratio of core-shell structured heat storage material to catalyst of 0.3:1.

[0090] The core-shell structured heat storage material and catalyst in the catalyst bed are non-uniformly mixed. The catalyst bed is divided into three parts from top to bottom: Part 1, Part 2, and Part 3. The volume ratio of Part 1 to Part 2 is 1:1, and the volume ratio of Part 2 to Part 3 is 0.125:1. Parts 1 and 3 consist of catalyst. Part 2 consists of catalyst and core-shell structured heat storage material, with a volume ratio of catalyst to core-shell structured heat storage material of 3:1. In the catalyst bed, the catalyst accounts for 77% of the bed volume.

[0091] The propane dehydrogenation to propylene reaction was carried out in a reactor packed with the aforementioned catalyst bed. The dehydrogenation reaction employed a reaction-regeneration cycle: 10 minutes of reaction followed by 1 minute of nitrogen purging, then 10 minutes of regeneration, 1 minute of nitrogen purging, and 1 minute of evacuation. The reaction temperature was 600℃, the pressure was 50 kPa absolute, and the propane space velocity was 0.7 hr⁻¹. -1 The regenerated air temperature was 650℃. The reaction results showed a propane conversion rate of 50.8% and a propylene selectivity of 90.4%.

[0092] Example 16

[0093] In a catalyst bed containing Cr metal, a core-shell structured heat storage material prepared in Example 3 was added, with a volume ratio of core-shell structured heat storage material to catalyst of 0.1:1.

[0094] catalyst bed such as Figure 5 As shown, a portion of Al2O3 ceramic balls are also added to the bed, with a volume ratio of Al2O3 ceramic balls to the core-shell structure heat storage material of 0.1. The core-shell structure heat storage material, Al2O3 ceramic balls, and catalyst are uniformly mixed. In the catalyst bed, the catalyst occupies 90% of the bed volume.

[0095] The dehydrogenation of isobutane to isobutene was carried out in a reactor packed with the aforementioned catalyst bed. The dehydrogenation reaction was conducted in a reaction-regeneration cycle: reaction time 10 minutes, nitrogen purging for 1 minute, regeneration time 10 minutes, nitrogen purging for 1 minute, and evacuation for 1 minute. The reaction temperature was 560℃, the pressure was 100 kPa absolute, and the propane space velocity was 0.8 hr⁻¹. -1 The regenerated air temperature was 600℃. The reaction results showed an isobutane conversion rate of 49.6% and an isobutene selectivity of 89.6%.

[0096] Example 17

[0097] In a catalyst bed containing Pt metal, a core-shell structured heat storage material prepared in Example 4 was added, with a volume ratio of core-shell structured heat storage material to catalyst of 0.2:1.

[0098] A portion of Al2O3 ceramic balls is also added to the catalyst bed, with a volume ratio of Al2O3 ceramic balls to the core-shell structure heat storage material of 0.2. The core-shell structure heat storage material, Al2O3 ceramic balls, and catalyst are uniformly mixed. In the catalyst bed, the catalyst occupies 81% of the bed volume.

[0099] Five reactors packed with the aforementioned catalyst beds were used for propane dehydrogenation to propylene. The reactors alternated between reaction, purging, regeneration, evacuation, and reduction processes, with each cycle consisting of 10 minutes of reaction, 1 minute of purging, 10 minutes of regeneration, 1 minute of evacuation, and 2 minutes of reduction. The reaction temperature was 620°C, the pressure was 40 kPa absolute, and the propane space velocity was 1.2 hr. -1 The regenerated air temperature was 660℃. The reaction results showed a propane conversion rate of 53.6% and a propylene selectivity of 91.4%.

[0100] Example 18

[0101] In a catalyst bed containing Pt metal, a core-shell structured heat storage material prepared in Example 5 was added, with a volume ratio of core-shell structured heat storage material to catalyst of 0.2:1.

[0102] A portion of Al2O3 ceramic balls is also added to the catalyst bed, with a volume ratio of Al2O3 ceramic balls to the core-shell structured heat storage material of 1. The core-shell structured heat storage material, Al2O3 ceramic balls, and catalyst are uniformly mixed. In the catalyst bed, the catalyst occupies 71% of the bed volume.

[0103] Ten reactors packed with the aforementioned catalyst beds were used for propane dehydrogenation to propylene. The reactors alternated between reaction, purging, regeneration, evacuation, and reduction processes, with each cycle consisting of 10 minutes of reaction, 1 minute of purging, 10 minutes of regeneration, 1 minute of evacuation, and 2 minutes of reduction. The reaction temperature was 650°C, the pressure was 50 kPa absolute, and the propane space velocity was 2.0 hr⁻¹. -1 The regenerated air temperature was 700℃. The reaction results showed a propane conversion rate of 57.5% and a propylene selectivity of 85.8%.

[0104] Example 19

[0105] In a catalyst bed containing Pt metal, a core-shell structured heat storage material prepared in Example 6 was added, with a volume ratio of core-shell structured heat storage material to catalyst of 0.2:1.

[0106] A portion of Al2O3 ceramic balls is also added to the catalyst bed, with a volume ratio of Al2O3 ceramic balls to the core-shell structure heat storage material of 0.6. The core-shell structure heat storage material, Al2O3 ceramic balls, and catalyst are uniformly mixed. In the catalyst bed, the catalyst occupies 76% of the bed volume.

[0107] Eight reactors packed with the aforementioned catalyst beds were used for propane dehydrogenation to propylene. The reactors alternated between reaction, purging, regeneration, evacuation, and reduction processes, with each cycle consisting of 10 minutes of reaction, 1 minute of purging, 10 minutes of regeneration, 1 minute of evacuation, and 2 minutes of reduction. The reaction temperature was 640℃, the pressure was 60 kPa absolute, and the propane space velocity was 1.5 hr⁻¹. -1 The regenerated air temperature was 700℃. The reaction results showed a propane conversion rate of 56.0% and a propylene selectivity of 87.6%.

[0108] Example 20

[0109] The core-shell structured heat storage material prepared in Example 1 was added to the catalyst bed containing Cr metal, with a volume ratio of core-shell structured heat storage material to catalyst of 0.1:1.

[0110] A portion of Al2O3 ceramic balls is also added to the catalyst bed, with a volume ratio of Al2O3 ceramic balls to the core-shell structure heat storage material of 0.5. The core-shell structure heat storage material, Al2O3 ceramic balls, and catalyst are uniformly mixed. In the catalyst bed, the catalyst occupies 87% of the bed volume.

[0111] Eight reactors packed with the aforementioned catalyst beds were used for propane dehydrogenation to propylene. The reactors alternated between reaction, purging, regeneration, evacuation, and reduction processes, with each cycle consisting of 10 minutes of reaction, 1 minute of purging, 10 minutes of regeneration, 1 minute of evacuation, and 2 minutes of reduction. The reaction temperature was 640℃, the pressure was 100 kPa absolute, and the propane space velocity was 1.2 hr⁻¹. -1 The regenerated air temperature was 660℃. The reaction results showed a propane conversion rate of 48.3% and a propylene selectivity of 90.5%.

[0112] Comparative Example 1

[0113] In a Cr-containing catalyst bed, Al2O3 ceramic balls are added, with a volume ratio of Al2O3 ceramic balls to catalyst of 1:1. The catalyst bed is as follows: Figure 3 As shown, the Al2O3 ceramic balls and catalyst are uniformly mixed. In the catalyst bed, the catalyst occupies 50% of the bed volume. This is significantly lower than the levels in the examples.

[0114] The propane dehydrogenation to propylene reaction was carried out in a reactor packed with the aforementioned catalyst bed. The dehydrogenation reaction employed a reaction-regeneration cycle: reaction time 10 minutes, nitrogen purging for 1 minute, regeneration time 10 minutes, nitrogen purging for 1 minute, and evacuation for 1 minute. The reaction temperature was 600℃, the pressure was 50 kPa absolute, and the propane space velocity was 0.6 hr⁻¹. -1 The regenerated air temperature was 650℃. The reaction results showed a propane conversion rate of 45.2% and a propylene selectivity of 88.6%.

[0115] Comparative Example 2

[0116] In a Cr-containing catalyst bed, a core-shell structured heat storage material prepared in Example 1 was added, with a volume ratio of core-shell structured heat storage material to catalyst of 0.02:1. The core-shell structured heat storage material and catalyst were uniformly mixed in the catalyst bed, and the catalyst accounted for 98% of the bed volume.

[0117] The propane dehydrogenation to propylene reaction was carried out in a reactor packed with the aforementioned catalyst bed. The dehydrogenation reaction employed a reaction-regeneration cycle: reaction time 10 minutes, nitrogen purging for 1 minute, regeneration time 10 minutes, nitrogen purging for 1 minute, and evacuation for 1 minute. The reaction temperature was 600℃, the pressure was absolute 50 kPa, the propane space velocity was 0.6 hr⁻¹, and the regeneration air temperature was 650℃. The results showed a propane conversion of 35.2% and a propylene selectivity of 92.5%.

[0118] Comparative Example 3

[0119] In a Cr-containing catalyst bed, a core-shell structured heat storage material prepared in Example 1 was added, with a volume ratio of core-shell structured heat storage material to catalyst of 0.4:1. The core-shell structured heat storage material and catalyst were uniformly mixed in the catalyst bed. The catalyst accounted for 71% of the bed volume.

[0120] The propane dehydrogenation to propylene reaction was carried out in a reactor packed with the aforementioned catalyst bed. The dehydrogenation reaction employed a reaction-regeneration cycle: reaction time 10 minutes, nitrogen purging for 1 minute, regeneration time 10 minutes, nitrogen purging for 1 minute, and evacuation for 1 minute. The reaction temperature was 600℃, the pressure was 50 kPa absolute, and the propane space velocity was 0.6 hr⁻¹. -1 The regenerated air temperature was 650℃. The reaction results showed a propane conversion rate of 53.6% and a propylene selectivity of 76.2%.

[0121] Comparative Example 4

[0122] The core-shell structured heat storage material prepared in Example 1 was added to a catalyst bed containing Cr metal, with a volume ratio of core-shell structured heat storage material to catalyst of 0.2:1.

[0123] In the catalyst bed, the core-shell structured heat storage material and the catalyst are non-uniformly mixed. The catalyst bed is as follows: Figure 4 As shown, the bed is divided into three parts from top to bottom: Part 1, Part 2, and Part 3. The volume ratio of Part 1 to Part 2 is 0.1:1, and the volume ratio of Part 2 to Part 3 is 1:1. Parts 1 and 2 consist of catalyst and core-shell structured heat storage material. In Part 1, the volume ratio of catalyst to core-shell structured heat storage material is 4:1, and in Part 2, it is 0.02:1. Part 3 consists of catalyst. In the catalyst bed, the catalyst occupies 83% of the bed volume.

[0124] The propane dehydrogenation to propylene reaction was carried out in a reactor packed with the aforementioned catalyst bed. The dehydrogenation reaction employed a reaction-regeneration cycle: reaction time 10 minutes, nitrogen purging for 1 minute, regeneration time 10 minutes, nitrogen purging for 1 minute, and evacuation for 1 minute. The reaction temperature was 600℃, the pressure was absolute 80 kPa, and the propane space velocity was 0.4 hr⁻¹. -1 The regenerated air temperature was 600℃. The reaction results showed a propane conversion rate of 37.2% and a propylene selectivity of 87.8%.

[0125] Comparative Example 5

[0126] The core-shell structured heat storage material prepared in Example 1 was added to a catalyst bed containing Cr metal, with a volume ratio of core-shell structured heat storage material to catalyst of 0.2:1.

[0127] catalyst bed such as Figure 5 As shown, a portion of Al2O3 ceramic balls is also added, with a volume ratio of Al2O3 ceramic balls to the core-shell structure heat storage material of 3:1. The core-shell structure heat storage material, Al2O3 ceramic balls, and catalyst are uniformly mixed. In the catalyst bed, the catalyst occupies 56% of the bed volume.

[0128] The propane dehydrogenation to propylene reaction was carried out in a reactor packed with the above-mentioned catalyst bed. The dehydrogenation reaction was conducted in a reaction-regeneration cycle: reaction time 10 minutes, nitrogen purging for 1 minute, regeneration time 10 minutes, nitrogen purging for 1 minute, and evacuation for 1 minute. The reaction temperature was 600℃, the pressure was 50 kPa absolute, and the propane space velocity was 0.6 hr. -1 The regenerated air temperature was 650℃. The reaction results showed a propane conversion rate of 47.1% and a propylene selectivity of 89.9%.

[0129] The reaction conditions of Examples 7-20 and Comparative Examples 1-5 are compared as shown in Tables 2-1 to 2-4:

[0130] Table 2-1 Summary of Main Conditions

[0131]

[0132] Table 2-2 Summary of Main Conditions

[0133]

[0134]

[0135] Table 2-3 Summary of Main Conditions

[0136]

[0137] Table 2-4 Summary of Main Conditions

[0138]

[0139]

[0140] *: Comparative Example 1 uses an inert particle / catalyst bed and no core-shell structure thermal storage material.

[0141] The reaction results of Examples 7-20 and Comparative Examples 1-5 are compared as shown in Tables 3-1 to 3-4:

[0142] Table 3-1 Summary of Reaction Results

[0143] reaction results Example 7 Example 8 Example 9 Example 10 Example 11 catalyst volume ratio in the bed % 91 83 77 95 91 Conversion rate % 47.2 50.2 51.4 46.1 48.5 Selectivity % 90.8 90.6 88.5 92.0 91.6

[0144] Table 3-2 Summary of Reaction Results

[0145] reaction results Example 12 Example 13 Example 14 Example 15 Example 16 catalyst volume ratio in the bed % 83 77 95 77 90 Conversion rate % 51.8 55.2 47.1 50.8 49.6 Selectivity % 91.1 87.5 86.2 90.4 89.6

[0146] Table 3-3 Summary of Reaction Results

[0147] reaction results Example 17 Example 18 Example 19 Example 20 catalyst volume ratio in the bed % 81 71 76 87 Conversion rate % 53.6 57.5 56.0 48.3 Selectivity % 91.4 85.8 87.6 90.5

[0148] Table 3-4 Summary of Reaction Results

[0149] reaction results Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 catalyst volume ratio in the bed % 50 98 71 83 56 Conversion rate % 45.2 35.2 53.6 37.2 47.1 Selectivity % 88.6 92.5 76.2 87.8 89.9

[0150] As shown in Tables 3-1 to 3-4, compared with the reaction results shown in Comparative Example 1, the method for improving the space utilization of the alkane dehydrogenation reactor provided by this invention results in a significantly higher catalyst-to-bed volume ratio. Compared with the reaction results shown in Comparative Examples 2 and 3, controlling the volume ratio of core-shell regenerative material / catalyst within the range provided by this invention yields better reaction conversion and selectivity. Compared with the reaction results shown in Comparative Example 4, controlling the non-uniform loading of the core-shell regenerative material / catalyst within the range provided by this invention results in better reaction conversion and selectivity. Compared with the reaction results shown in Comparative Example 5, controlling the volume ratio of Al2O3 ceramic balls / core-shell regenerative material within the range provided by this invention results in a significantly higher catalyst-to-bed volume ratio.

[0151] 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.

[0152] 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 of increasing the space utilization of an alkane dehydrogenation reactor, characterized by, The heat storage material is added in the reactor catalyst bed; The heat storage material comprises core-shell structure heat storage material and Al2O3 ceramic ball; the core-shell structure heat storage material comprises high-temperature-resistant shell and metal alloy inner core; the volume ratio of the total amount of Al2O3 ceramic ball to the total amount of core-shell structure heat storage material is (0.1-1):1; The high-temperature-resistant shell is inert metal oxide; The metal alloy inner core is aluminum alloy, and the melting point of the metal alloy inner core is 500-650 ℃; The particle size of the core-shell structure heat storage material is 3-50 mm; wherein the thickness of the high-temperature-resistant shell is 10-500 μm; The volume ratio of the core-shell structure heat storage material to the catalyst is (0.05-0.3):1; The heat storage material and the catalyst are distributed in the catalyst bed in a segmented manner; the catalyst bed is divided into three or more sections from top to bottom, wherein the volume ratio of the upper section to the lower section in the adjacent two sections is (0.1-10):1; each section is composed of a mixture of catalyst and / or heat storage material, and the volume ratio of the heat storage material to the catalyst in each section is (0.01-3):

1.

2. The method of claim 1, wherein, The high-temperature-resistant shell is selected from alumina, silicon oxide, alumina and silicon oxide; And / or, the volume ratio of the total amount of Al2O3 ceramic ball to the total amount of core-shell structure heat storage material is (0.2-0.5):1; And / or, the volume ratio of the core-shell structure heat storage material to the catalyst is (0.1-0.2):

1.

3. The method of claim 2, wherein, The alumina comprises α-alumina and γ-alumina.

4. The method according to any one of claims 1 to 3, characterized in that, The particle size of the core-shell structure heat storage material is 10-20 mm; And / or, the particle size of the metal alloy inner core is 2-49 mm; And / or, the metal alloy inner core is selected from aluminum-magnesium alloy and cast aluminum alloy; And / or, the melting point of the metal alloy inner core is 560-620 ℃.

5. The method according to any one of claims 1 to 3, characterized in that, The volume ratio of the heat storage material to the catalyst in each section is (0.05-0.5):

1.

6. The method according to any one of claims 1 to 3, characterized in that, The catalyst is a catalyst containing at least one of Cr or Pt.

7. A process for the dehydrogenation of an alkane to lower alkenes, characterized in that, The method comprises filling the reactor catalyst bed by using the method for improving the space utilization rate of the alkane dehydrogenation reactor according to any one of claims 1-6, introducing one or more alkane of propane, n-butane and isobutane for dehydrogenation reaction to produce low-carbon olefins.

8. The process for the dehydrogenation of an alkane to lower olefins according to claim 7, characterized in that, The dehydrogenation reaction temperature is 550-650℃, the pressure is 20-100kPa, the reaction gas mass space velocity is 0.4-2hr -1 .

9. The process for the dehydrogenation of an alkane to lower olefins according to claim 7 or 8, characterized in that, The method comprises: arranging 3-10 parallel alkane dehydrogenation reactors, and alternately producing low-carbon olefins according to reaction, purging, regeneration, evacuation and reduction.

10. The process for the dehydrogenation of an alkane to lower olefins according to claim 7 or 8, characterized in that, The regeneration adopts air regeneration, and the regeneration air temperature used is 600-700 ℃.

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