Method for improving space utilization rate of alkane dehydrogenation reactor and method for preparing low-carbon olefin through alkane dehydrogenation

Abstract

The invention provides a method for improving the space utilization rate of an alkane dehydrogenation reactor, and mainly solves the problems of small occupied volume of a catalyst in a bed layer and low space utilization rate of the reactor due to mixing of the catalyst and a large amount of heat storage particles in the existing propane dehydrogenation reactor. Comprising the steps that a core-shell structure heat storage material with a core-shell structure is mixed in a reactor catalyst bed layer, the core-shell structure heat storage material is composed of a high-temperature-resistant shell and a metal alloy core, and the volume ratio of the core-shell structure heat storage material to a catalyst is (0.05-0.3): 1. By adopting the technical scheme, the space utilization rate of the alkane dehydrogenation reactor is increased by more than 25%, the volume of the catalyst in the bed layer is greatly increased, the equipment size can be obviously reduced, and the production capacity is improved. Meanwhile, by better matching the temperature distribution of the catalyst bed and the endothermic degree of the dehydrogenation reaction process, the conversion rate and selectivity of the reaction are obviously improved, and the method has obvious technical advantages and good application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of petrochemical industry, and specifically relates to a method for improving the space utilization rate of an alkane dehydrogenation reactor and a method for preparing low-carbon olefins by dehydrogenating alkane. Background Art

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

[0003] With the growth in demand for light olefins, especially propylene, in recent years, the light olefins produced by traditional methods such as catalytic cracking and steam cracking by-products can no longer meet the supply. Therefore, technologies for expanding the source of light olefins, represented by the dehydrogenation of light alkanes to produce olefins, have been widely used.

[0004] Taking propylene as an example, the current mainstream propane dehydrogenation to propylene processes mainly include UOP's Oleflex process and ABB Lummus's Catofin process. Among them, the Catofin process has the advantages of high conversion rate, good selectivity, high online rate, and strong raw material adaptability. Therefore, it has received more and more attention and has been promoted and applied. In the Catofin process, the propane dehydrogenation to propylene reaction absorbs a lot of heat, causing the catalyst bed temperature to decrease. At the same time, the carbon deposits generated by the reaction will also cause the catalyst activity to decrease rapidly. Therefore, in order to ensure that the catalyst activity is within the optimal range, it is necessary to regenerate once every period of time and heat the catalyst bed again to accumulate a certain amount of heat to prepare for the next reaction. The propane dehydrogenation reaction is usually operated under high temperature, negative pressure or low pressure conditions, and the effect of temperature on the reaction is very significant. Excessive reaction temperature will lead to the occurrence of side reactions such as propane cracking, and further produce carbon deposits to reduce the activity of the catalyst, resulting in a decrease in selectivity. On the other hand, too low a reaction temperature will cause a rapid decrease in conversion. When the catalyst bed temperature is unevenly distributed, it will lead to the appearance of local hot spots or local cold spots, resulting in a decrease in conversion rate or selectivity. Therefore, heat storage and temperature control of the catalyst bed are very critical issues in propane dehydrogenation reaction.

[0005] During the dehydrogenation reaction, almost all the heat absorbed by the dehydrogenation of low-carbon alkanes comes from the heat storage of the catalyst bed, so the heat storage capacity of the bed determines how long the dehydrogenation reaction can last. Due to the large amount of cracking of low-carbon alkanes at high temperatures above 650°C, the maximum temperature of the catalyst bed is limited. In order 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 materials.

[0006] The commonly used heat storage material is inert alumina (component is Al2O3). Depending on the raw materials of the dehydrogenation reaction, the ratio of inert alumina to catalyst is not exactly the same. For the propane dehydrogenation process, the volume of inert alumina can account for about 50% of the volume of the entire catalyst bed; and for the isobutane dehydrogenation process, the volume of inert alumina can account for about 30% of the volume of the entire catalyst bed. Therefore, the catalyst actually used for the dehydrogenation reaction in the catalyst bed only accounts for about 50-70% of the volume of the entire catalyst bed. A large amount of reactor space is occupied by inert alumina used for heat storage, and the space utilization rate of the alkane dehydrogenation reactor is low, which affects the production capacity of the device and has to increase the size of the equipment.

[0007] In some of the latest technical reports, a method of supplementing the heat required for the dehydrogenation reaction stage by increasing the heat supply in the catalyst bed of the reactor is disclosed. For example, CN104072325A discloses a method for improving the performance of the dehydrogenation reaction of light alkanes, which uses a fixed bed reactor with a built-in electric heating tube to provide heat for the catalyst bed during the dehydrogenation process to reduce the temperature drop caused by the endothermic reaction, and reduces the thermal cracking of light alkanes by reducing the heat load of the electric heater in front of the reactor, thereby ultimately improving the performance of the dehydrogenation reaction of light alkanes.

[0008] CN113149802A discloses an improved method and device for producing olefins by dehydrogenating low-carbon alkanes in a fixed bed, which adopts an alumina additive loaded with elements of Group IB and IIA, and a built-in heating pipe for the bed of gas, molten salt, and caustic high-temperature heat medium to achieve heat balance in the conversion process and temperature balance in the reaction bed, thereby reducing the severity of the reaction process, temperature difference, thermal cracking and coking side reactions, and improving the conversion activity, selectivity, single-pass reaction time, operation stability and maintainability.

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

[0010] In other technical reports, reports of adding heat-generating materials in the catalyst reaction bed are also disclosed. For example, CN106029612A discloses an improved alkane endothermic dehydrogenation process using heat-generating materials. In the process, in addition to using CATOFIN@300 catalyst and inert alumina, HGM heat-generating materials (metal elements such as copper and manganese are loaded on alumina) are also used, including reacting hydrocarbons with a multi-component catalyst bed and regenerating the catalyst bed using air, wherein the air and hydrocarbons used in the regeneration step are at a low air / hydrocarbon ratio and a pressure close to atmospheric pressure, which improves the efficiency of the process. The added heat-generating materials are mainly used to provide heat to reduce the air consumption during the regeneration process, and cannot increase the heat storage capacity of the bed, and a large amount of inert alumina still needs to be added to the catalyst bed.

[0011] CN107074683A discloses a method for catalytically dehydrogenating alkanes to olefins using a Cr2O3 catalyst, wherein a CuO 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. CO reacts with CuO to form Cu and CO2, releasing heat. However, this method introduces components such as CO and CO2 while introducing heat, causing a decrease in the partial pressure of the reaction gas, affecting the reaction conversion rate.

[0012] CN108300430B discloses an alkane dehydrogenation exothermic additive and its preparation method and use method, which stores heat in the catalyst regeneration stage and releases heat during the catalytic reaction, thereby inhibiting the temperature reduction of the reaction process. The heat sources in the additive are mainly: CuO reacts with H2 to release heat and generate water, the heat-generating material absorbs water and releases heat, and the additive itself stores part of the heat as a heat medium. However, this method requires the consumption of additional hydrogen, and the generated water will accelerate the formation of α-chromium-aluminum in the catalyst, resulting in a significant decrease in the reaction conversion rate.

[0013] At present, in the process of dehydrogenation of low-carbon alkanes, the problem of low space utilization of the reactor caused by the heat storage problem of the catalyst bed has been widely recognized in the industry. Many scholars have also proposed solutions to the above problems by using various means or combinations of built-in heating tubes, heating materials, exothermic additives, etc. However, due to various reasons, they will have certain adverse effects on the existing process and need further improvement and enhancement. Summary of the invention

[0014] In order to solve the above problems in the prior art, the present invention provides a method for improving the space utilization rate of an alkane dehydrogenation reactor and a method for producing light olefins by dehydrogenating alkane.

[0015] In the 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 into a catalyst bed of the reactor, wherein the heat storage material comprises a core-shell structure heat storage material and an Al2O3 porcelain ball; the core-shell structure heat storage material consists of a high temperature resistant outer shell and a metal alloy inner core; the volume ratio of the Al2O3 porcelain ball 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 shell is an inert metal oxide, preferably, selected from alumina, α-alumina, γ-alumina, silica, alumina and silica.

[0017] As a specific embodiment of the present invention, the metal alloy core is an aluminum alloy, preferably selected from aluminum-magnesium alloy and 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 thermal 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 method for preparing the core-shell structure thermal storage material comprises the following steps:

[0020] S1: preparing the alloy core material into small balls with a desired particle size by mechanical processing to obtain the metal alloy core;

[0021] S2: thermal spraying the surface of the metal alloy core obtained in step S1 once or multiple times to obtain the high temperature resistant shell to obtain the core-shell structure thermal storage material;

[0022] Optionally, S3: the core-shell structure thermal storage material prepared in step S2 is immersed in SiO2 sol for 1 min, and the immersed material is dried to obtain the core-shell structure thermal storage material.

[0023] As a specific embodiment of the present invention, the heat storage material and the catalyst are distributed in sections 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 two adjacent sections is (0.1-10):1;

[0025] Each section is composed of a mixture of catalyst and / or heat storage material. The ratio of heat storage material to catalyst in each section is different. 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 near the middle and upper part is a better choice, both the selectivity and conversion rate can be improved. Arranging it close to the outlet can greatly improve the conversion rate and the selectivity change is not obvious.

[0027] The core-shell structure heat storage material provided by the present invention realizes heat storage by using the phase change heat of metal alloy. Specifically, in the dehydrogenation process of low-carbon alkanes, the core-shell structure heat storage material and the catalyst in the reactor bed are heated to 600-650°C by regeneration air. During the regeneration process, the metal alloy core absorbs heat and melts into a liquid phase, thereby realizing a large amount of heat storage. In the dehydrogenation reaction stage, the reaction temperature is 560-620°C, and 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 structure heat storage material provided by the present invention is an aluminum alloy, and its phase change heat in the melting process is about 250-550 kJ / kg, while the heat capacity of inert alumina is about 0.7-0.9 kJ / kg°C. In the same dehydrogenation reaction process, the heat that can be provided by the core-shell structure heat storage material provided by the present invention is 6-10 times that of the same mass of inert alumina. Therefore, compared with the inert alumina thermal storage material used in the prior art, the catalyst actually used for the dehydrogenation reaction in the catalyst bed only accounts for about 50-70% of the volume of the entire catalyst bed. However, by using the core-shell thermal storage material provided by the present invention, the catalyst actually used for the dehydrogenation reaction in the catalyst bed can account for 71-95% of the volume of the entire catalyst bed, and the space utilization rate of the alkane dehydrogenation reactor is increased by more than 25%.

[0028] At the same time, considering that the heat absorption of catalyst beds at different heights during the dehydrogenation reaction is different, the core-shell structure heat storage material and the 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 of two adjacent parts is (0.1-10):1; each part can be optionally composed of a catalyst or a mixture of a catalyst and a core-shell structure heat storage material, and the ratio of the core-shell structure heat storage material to the catalyst in each part is different, and the volume ratio of the heat storage material to the catalyst is (0.01-3):1, preferably (0.05-0.5):1. In order to more accurately match the different degrees of heat absorption 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 of Cr or Pt.

[0030] In a second aspect, the present invention provides a method for dehydrogenating alkanes to produce light olefins. During the dehydrogenation reaction of one or more alkanes among propane, n-butane, and isobutane, the method for improving the space utilization of the alkane dehydrogenation reactor described in the first aspect is used to carry out dehydrogenation reaction to produce light olefins.

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

[0032] As a specific embodiment of the present invention, the method comprises producing light olefins by alternating the processes of reaction, purging, regeneration, evacuation and reduction by 3 to 10 parallel alkane dehydrogenation reactors.

[0033] As a specific implementation of the present invention, the regeneration process adopts air regeneration, and the regeneration air temperature is 600-700°C.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The core-shell structure heat storage material of the present invention adopts phase change heat storage, and 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 improving the space utilization rate of the alkane dehydrogenation reactor of the present invention has a low filling ratio of the core-shell structure heat storage material, and the catalyst occupies a greatly increased bed volume. The space utilization rate of the alkane dehydrogenation reactor is increased by more than 25%, which can significantly reduce the size of the reactor equipment and improve the production capacity.

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

[0038] 4. The method of improving the space utilization of the alkane dehydrogenation reactor of the present invention has a higher matching degree between the temperature distribution of the catalyst bed and the degree of heat absorption during the dehydrogenation reaction, and the reaction is controlled within the range of the optimal catalyst activity, and the reaction conversion rate and selectivity are significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0041] Figure 3 A schematic diagram of a catalyst bed provided by the prior art;

[0042] Figure 4 A schematic diagram of a catalyst bed in a preferred form 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-the first part of the catalyst bed, 1b-the second part of the catalyst bed, 1c-the third part of the catalyst bed; 2-catalyst; 3-core-shell structure heat storage material, 3a-high temperature resistant shell, 3b-metal alloy core; 4-alumina ceramic ball. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with specific embodiments, but they do not constitute any limitation to the present invention.

[0046] The catalyst information used in each embodiment of the present invention is as follows:

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

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

[0049] The Al2O3 content in the Al2O3 porcelain balls used in the embodiments of the present invention is above 99%.

[0050] Example 1

[0051] This embodiment provides a core-shell structure thermal storage material and a preparation method thereof, the specific details of which are as follows:

[0052] S1: preparing the alloy core material into small balls with a desired particle size by mechanical processing to obtain the metal alloy core;

[0053] S2: thermal spraying the surface of the metal alloy core obtained in step S1 once or multiple times to obtain the high temperature resistant shell to obtain the core-shell structure thermal storage material;

[0054] S3: Optionally, the core-shell structure heat storage material prepared in step S2 is immersed in SiO2 sol for 1 min, and the immersed material is dried to obtain the core-shell structure 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, the alloy material of the inner core is aluminum-magnesium alloy, the melting point of the metal alloy inner core is 580° C., and the particle size is 10 mm.

[0056] Embodiments 2 to 6

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

[0058] Table 1 Core-shell structure thermal storage materials prepared in Examples 1 to 6

[0059]

[0060] Example 7

[0061] The core-shell structure heat storage material prepared in Example 1 was added to the catalyst bed containing Cr metal, and the volume ratio of the core-shell structure heat storage material to the catalyst was 0.1:1. The core-shell structure heat storage material and the catalyst in the catalyst bed were uniformly mixed, such as Figure 1 In the catalyst bed, the catalyst accounts for 91% of the volume of the bed.

[0062] The propane dehydrogenation to propylene reaction was carried out in a reactor filled with the above catalyst bed. The dehydrogenation reaction was carried out in a reaction-regeneration cycle mode, with a reaction time of 10 minutes, a nitrogen purge of 1 minute, a regeneration of 10 minutes, a nitrogen purge of 1 minute, and an evacuation of 1 minute. The reaction temperature was 600°C, the pressure was 50 kPa absolute, and the propane space velocity was 0.6 hr -1 , regeneration air temperature 650° C. The reaction results were propane conversion 47.2% and propylene selectivity 90.8%.

[0063] Example 8

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

[0065] The propane dehydrogenation to propylene reaction was carried out in a reactor filled with the above catalyst bed. The dehydrogenation reaction was carried out in a reaction-regeneration cycle mode, with a reaction time of 10 minutes, a nitrogen purge of 1 minute, a regeneration of 10 minutes, a nitrogen purge of 1 minute, and an evacuation of 1 minute. The reaction temperature was 600°C, the pressure was 50 kPa absolute, and the propane space velocity was 0.6 hr -1 , regeneration air temperature 650° C. The reaction results were propane conversion 50.2% and propylene selectivity 90.6%.

[0066] Example 9

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

[0068] The propane dehydrogenation to propylene reaction was carried out in a reactor filled with the above catalyst bed. The dehydrogenation reaction was carried out in a reaction-regeneration cycle mode, with a reaction time of 10 minutes, a nitrogen purge of 1 minute, a regeneration of 10 minutes, a nitrogen purge of 1 minute, and an evacuation of 1 minute. The reaction temperature was 600°C, the pressure was 50 kPa absolute, and the propane space velocity was 0.6 hr -1 , regeneration air temperature 650° C. The reaction results were propane conversion 51.4% and propylene selectivity 88.5%.

[0069] Example 10

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

[0071] The reaction of propane dehydrogenation to propylene was carried out in a reactor filled with the above catalyst bed. The dehydrogenation reaction was carried out in a reaction-regeneration cycle mode, with a reaction time of 10 minutes, a nitrogen purge of 1 minute, a regeneration of 10 minutes, a nitrogen purge of 1 minute, and an evacuation of 1 minute. The reaction temperature was 600°C, the pressure was 80 kPa absolute pressure, and the propane space velocity was 0.4 hr -1 , the regeneration air temperature is 600° C. The reaction results are propane conversion of 46.1% and propylene selectivity of 92.0%.

[0072] Embodiment 11

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

[0074] The core-shell structure heat storage material and the catalyst in the catalyst bed are mixed non-uniformly. Figure 4As shown, it is divided into three parts from top to bottom, namely the first part, the second part and the third part, the volume ratio of the first part to the second part is 0.5, and the volume ratio of the second part to the third part is 0.8. The first part and the second part are composed of catalyst and core-shell structure thermal storage material, wherein the volume ratio of catalyst to core-shell structure thermal storage material in the first part is 0.05:1, and the volume ratio of catalyst to core-shell structure thermal storage material in the second part is 0.25:1. The third part is composed of catalyst. In the catalyst bed, the proportion of catalyst to the bed volume is 91%.

[0075] The propane dehydrogenation to propylene reaction was carried out in a reactor filled with the above catalyst bed. The dehydrogenation reaction was carried out in a reaction-regeneration cycle mode, with a reaction time of 10 minutes, a nitrogen purge of 1 minute, a regeneration of 10 minutes, a nitrogen purge of 1 minute, and an evacuation of 1 minute. The reaction temperature was 600°C, the pressure was 50 kPa absolute, and the propane space velocity was 0.6 hr -1 , regeneration air temperature 650° C. The reaction results were propane conversion 48.5% and propylene selectivity 91.6%.

[0076] Example 12

[0077] The core-shell structure thermal storage material prepared in Example 1 was added to the catalyst bed containing Cr metal, and the volume ratio of the core-shell structure thermal storage material to the catalyst was 0.2:1.

[0078] The core-shell structure heat storage material and the catalyst in the catalyst bed are mixed non-uniformly. The catalyst bed is divided into three parts from top to bottom, namely the first part, the second part and the third part. The volume ratio of the first part to the second part is 0.1, and the volume ratio of the second part to the third part is 2. The first part and the second part are composed of catalyst and core-shell structure heat storage material, wherein the volume ratio of the catalyst to the core-shell structure heat storage material in the first part is 0.2:1, and the volume ratio of the catalyst to the core-shell structure heat storage material in the second part is 0.3:1. The third part is composed of catalyst. In the catalyst bed, the proportion of catalyst to the bed volume is 83%.

[0079] The propane dehydrogenation to propylene reaction was carried out in a reactor filled with the above catalyst bed. The dehydrogenation reaction was carried out in a reaction-regeneration cycle mode, with a reaction time of 10 minutes, a nitrogen purge of 1 minute, a regeneration of 10 minutes, a nitrogen purge of 1 minute, and an evacuation of 1 minute. The reaction temperature was 600°C, the pressure was 50 kPa absolute, and the propane space velocity was 0.6 hr -1 , regeneration air temperature 650° C. The reaction results were propane conversion 51.8% and propylene selectivity 91.1%.

[0080] Embodiment 13

[0081] The core-shell structure thermal storage material prepared in Example 1 was added to the catalyst bed containing Cr metal, and the volume ratio of the core-shell structure thermal storage material to the catalyst was 0.3:1.

[0082] The core-shell structure heat storage material and the catalyst in the catalyst bed are mixed non-uniformly. The catalyst bed is divided into three parts from top to bottom, namely the first part, the second part and the third part, the volume ratio of the first part to the second part is 0.01, and the volume ratio of the second part to the third part is 10. The first part is composed of catalyst. The second and third parts are composed of catalyst and core-shell structure heat storage material, wherein the volume ratio of catalyst to core-shell structure heat storage material in the second part is 0.3:1, and the volume ratio of catalyst to core-shell structure heat storage material in the third part is 0.33:1. In the catalyst bed, the proportion of catalyst to the bed volume is 77%.

[0083] The propane dehydrogenation to propylene reaction was carried out in a reactor filled with the above catalyst bed. The dehydrogenation reaction was carried out in a reaction-regeneration cycle mode, with a reaction time of 10 minutes, a nitrogen purge of 1 minute, a regeneration of 10 minutes, a nitrogen purge of 1 minute, and an evacuation of 1 minute. The reaction temperature was 600°C, the pressure was 50 kPa absolute, and the propane space velocity was 0.6 hr -1 , regeneration air temperature 650° C. The reaction results were propane conversion 55.2% and propylene selectivity 87.5%.

[0084] Embodiment 14

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

[0086] The core-shell structure heat storage material and the catalyst in the catalyst bed are mixed non-uniformly. The catalyst bed is divided into three parts from top to bottom, namely the first part, the second part and the third part. The volume ratio of the first part to the second part is 0.5:1, and the volume ratio of the second part to the third part is 0.8:1. The first part and the second part are composed of catalyst and core-shell structure heat storage material, wherein the volume ratio of the catalyst to the core-shell structure heat storage material in the first part is 0.015:1, and the volume ratio of the catalyst to the core-shell structure heat storage material in the second part is 0.13:1. The third part is composed of catalyst. In the catalyst bed, the proportion of catalyst in the bed volume is 95%.

[0087] The reaction of n-butane dehydrogenation to n-butene was carried out in a reactor filled with the above catalyst bed. The dehydrogenation reaction was carried out in a reaction-regeneration cycle mode, with a reaction time of 10 minutes, a nitrogen purge of 1 minute, a regeneration of 10 minutes, a nitrogen purge of 1 minute, and an evacuation of 1 minute. The reaction temperature was 600°C, the pressure was 80 kPa absolute, and the propane space velocity was 0.4 hr -1, regeneration air temperature 600° C. The reaction results were n-butane conversion 47.1% and n-butene selectivity 86.2%.

[0088] Embodiment 15

[0089] The core-shell structure thermal storage material prepared in Example 1 was added to the catalyst bed containing Cr metal, and the volume ratio of the core-shell structure thermal storage material to the catalyst was 0.3:1.

[0090] The core-shell structure heat storage material and the catalyst in the catalyst bed are mixed non-uniformly. The catalyst bed is divided into three parts from top to bottom, namely the first part, the second part and the third part, the volume ratio of the first part to the second part is 1:1, and the volume ratio of the second part to the third part is 0.125:1. The first part and the third part are composed of catalysts. The second part is composed of catalysts and core-shell structure heat storage materials, wherein the volume ratio of catalysts to core-shell structure heat storage materials is 3:1. In the catalyst bed, the catalyst accounts for 77% of the volume of the bed.

[0091] The propane dehydrogenation to propylene reaction was carried out in a reactor filled with the above catalyst bed. The dehydrogenation reaction was carried out in a reaction-regeneration cycle mode, with a reaction time of 10 minutes, a nitrogen purge of 1 minute, a regeneration of 10 minutes, a nitrogen purge of 1 minute, and an evacuation of 1 minute. The reaction temperature was 600°C, the pressure was 50 kPa absolute pressure, and the propane space velocity was 0.7 hr -1 , regeneration air temperature 650° C. The reaction results were propane conversion 50.8% and propylene selectivity 90.4%.

[0092] Example 16

[0093] The core-shell structure heat storage material prepared in Example 3 was added to the catalyst bed containing Cr metal, and the volume ratio of the core-shell structure heat storage material to the catalyst was 0.1:1.

[0094] Catalyst bed Figure 5 As shown, a portion of Al2O3 ceramic balls are added to the bed layer, and the volume ratio of Al2O3 ceramic balls to core-shell structure thermal storage material is 0.1. The core-shell structure thermal storage material, Al2O3 ceramic balls and catalyst are uniformly mixed. In the catalyst bed layer, the catalyst accounts for 90% of the bed volume.

[0095] The isobutane dehydrogenation to isobutene reaction was carried out in a reactor filled with the above catalyst bed. The dehydrogenation reaction was carried out in a reaction-regeneration cycle mode, with a reaction time of 10 minutes, a nitrogen purge of 1 minute, a regeneration of 10 minutes, a nitrogen purge of 1 minute, and an evacuation of 1 minute. The reaction temperature was 560°C, the pressure was 100 kPa absolute pressure, and the propane space velocity was 0.8 hr -1 , the regeneration air temperature is 600° C. The reaction results are an isobutane conversion rate of 49.6% and an isobutene selectivity of 89.6%.

[0096] Embodiment 17

[0097] The core-shell structure thermal storage material prepared in Example 4 was added to the catalyst bed containing Pt metal, and the volume ratio of the core-shell structure thermal storage material to the catalyst was 0.2:1.

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

[0099] Five reactors loaded with the above catalyst beds were used to dehydrogenate propane to produce propylene. The reactors were alternately operated according to the process of reaction, purging, regeneration, evacuation, and reduction, wherein the reaction time was 10 minutes, purging time was 1 minute, regeneration time was 10 minutes, evacuation time was 1 minute, and reduction time was 2 minutes. The reaction temperature was 620°C, the pressure was 40 kPa absolute pressure, and the propane space velocity was 1.2 hr -1 , regeneration air temperature 660° C. The reaction results were propane conversion 53.6% and propylene selectivity 91.4%.

[0100] Embodiment 18

[0101] The core-shell structure thermal storage material prepared in Example 5 was added to the catalyst bed containing Pt metal, and the volume ratio of the core-shell structure thermal storage material to the catalyst was 0.2:1.

[0102] A portion of Al2O3 ceramic balls are also added to the catalyst bed, and the volume ratio of the Al2O3 ceramic balls to the core-shell structure thermal storage material is 1. The core-shell structure thermal storage material, the Al2O3 ceramic balls and the catalyst are uniformly mixed. In the catalyst bed, the catalyst accounts for 71% of the volume of the bed.

[0103] Ten reactors loaded with the above catalyst beds were used to dehydrogenate propane to produce propylene. The reactors were alternately operated according to the process of reaction, purging, regeneration, evacuation, and reduction, wherein the reaction time was 10 minutes, purging time was 1 minute, regeneration time was 10 minutes, evacuation time was 1 minute, and reduction time was 2 minutes. The reaction temperature was 650°C, the pressure was 50 kPa absolute pressure, and the propane space velocity was 2.0 hr -1 , the regeneration air temperature was 700° C. The reaction results were a propane conversion of 57.5% and a propylene selectivity of 85.8%.

[0104] Embodiment 19

[0105] The core-shell structure thermal storage material prepared in Example 6 was added to the catalyst bed containing Pt metal, and the volume ratio of the core-shell structure thermal storage material to the catalyst was 0.2:1.

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

[0107] Eight reactors loaded with the above catalyst beds were used to dehydrogenate propane to produce propylene. The reactors were alternately operated according to the process of reaction, purging, regeneration, evacuation, and reduction, wherein the reaction time was 10 minutes, purging time was 1 minute, regeneration time was 10 minutes, evacuation time was 1 minute, and reduction time was 2 minutes. The reaction temperature was 640°C, the pressure was 60 kPa absolute pressure, and the propane space velocity was 1.5 hr -1 , the regeneration air temperature was 700° C. The reaction results were a propane conversion of 56.0% and a propylene selectivity of 87.6%.

[0108] Embodiment 20

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

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

[0111] Eight reactors loaded with the above catalyst beds were used to dehydrogenate propane to produce propylene. The reactors were alternately operated according to the process of reaction, purging, regeneration, evacuation, and reduction, wherein the reaction time was 10 minutes, purging time was 1 minute, regeneration time was 10 minutes, evacuation time was 1 minute, and reduction time was 2 minutes. The reaction temperature was 640°C, the pressure was 100 kPa absolute pressure, and the propane space velocity was 1.2 hr -1 , regeneration air temperature 660° C. The reaction results were propane conversion 48.3% and propylene selectivity 90.5%.

[0112] Comparative Example 1

[0113] In the catalyst bed containing Cr metal, Al2O3 ceramic balls are added, and the volume ratio of Al2O3 ceramic balls to catalyst is 1:1. Figure 3 As shown, the Al2O3 ceramic balls and the catalyst are uniformly mixed. In the catalyst bed, the catalyst accounts for 50% of the bed volume, which is far lower than the level of the embodiment.

[0114] The propane dehydrogenation to propylene reaction was carried out in a reactor filled with the above catalyst bed. The dehydrogenation reaction was carried out in a reaction-regeneration cycle mode, with a reaction time of 10 minutes, a nitrogen purge of 1 minute, a regeneration of 10 minutes, a nitrogen purge of 1 minute, and an evacuation of 1 minute. The reaction temperature was 600°C, the pressure was 50 kPa absolute, and the propane space velocity was 0.6 hr -1 , regeneration air temperature 650° C. The reaction results were propane conversion 45.2% and propylene selectivity 88.6%.

[0115] Comparative Example 2

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

[0117] The reaction of propane dehydrogenation to propylene was carried out in a reactor filled with the above catalyst bed. The dehydrogenation reaction was carried out in a reaction-regeneration cycle mode, with a reaction time of 10 minutes, a nitrogen purge of 1 minute, a regeneration time of 10 minutes, a nitrogen purge of 1 minute, and an evacuation time of 1 minute. The reaction temperature was 600°C, the pressure was 50 kPa absolute pressure, the propane space velocity was 0.6 hr-1, and the regeneration air temperature was 650°C. The reaction results were a propane conversion rate of 35.2% and a propylene selectivity of 92.5%.

[0118] Comparative Example 3

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

[0120] The propane dehydrogenation to propylene reaction was carried out in a reactor filled with the above catalyst bed. The dehydrogenation reaction was carried out in a reaction-regeneration cycle mode, with a reaction time of 10 minutes, a nitrogen purge of 1 minute, a regeneration of 10 minutes, a nitrogen purge of 1 minute, and an evacuation of 1 minute. The reaction temperature was 600°C, the pressure was 50 kPa absolute, and the propane space velocity was 0.6 hr -1 , regeneration air temperature 650° C. The reaction results were propane conversion 53.6% and propylene selectivity 76.2%.

[0121] Comparative Example 4

[0122] The core-shell structure thermal storage material prepared in Example 1 was added to the catalyst bed containing Cr metal, and the volume ratio of the core-shell structure thermal storage material to the catalyst was 0.2:1.

[0123] The core-shell structure heat storage material and the catalyst in the catalyst bed are mixed non-uniformly. Figure 4 As shown, it is divided into three parts from top to bottom, namely the first part, the second part and the third part, the volume ratio of the first part to the second part is 0.1:1, and the volume ratio of the second part to the third part is 1:1. The first part and the second part are composed of catalysts and core-shell structure thermal storage materials, wherein the volume ratio of the catalyst to the core-shell structure thermal storage material in the first part is 4:1, and the volume ratio of the catalyst to the core-shell structure thermal storage material in the second part is 0.02:1. The third part is composed of catalysts. In the catalyst bed, the proportion of the catalyst to the bed volume is 83%.

[0124] The reaction of propane dehydrogenation to propylene was carried out in a reactor filled with the above catalyst bed. The dehydrogenation reaction was carried out in a reaction-regeneration cycle mode, with a reaction time of 10 minutes, a nitrogen purge of 1 minute, a regeneration of 10 minutes, a nitrogen purge of 1 minute, and an evacuation of 1 minute. The reaction temperature was 600°C, the pressure was 80 kPa absolute pressure, and the propane space velocity was 0.4 hr -1 , regeneration air temperature 600° C. The reaction results were propane conversion 37.2% and propylene selectivity 87.8%.

[0125] Comparative Example 5

[0126] The core-shell structure thermal storage material prepared in Example 1 was added to the catalyst bed containing Cr metal, and the volume ratio of the core-shell structure thermal storage material to the catalyst was 0.2:1.

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

[0128] The propane dehydrogenation to propylene reaction was carried out in a reactor filled with the above catalyst bed. The dehydrogenation reaction was carried out in a reaction-regeneration cycle mode, with a reaction time of 10 minutes, a nitrogen purge of 1 minute, a regeneration of 10 minutes, a nitrogen purge of 1 minute, and an evacuation of 1 minute. The reaction temperature was 600°C, the pressure was 50 kPa absolute, and the propane space velocity was 0.6 hr -1 , regeneration air temperature 650° C. The reaction results were propane conversion 47.1% and propylene selectivity 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 without a 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 Embodiment 11 Catalyst volume ratio in 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 Embodiment 13 Embodiment 14 Embodiment 15 Example 16 Catalyst volume ratio in 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 Embodiment 17 Embodiment 18 Embodiment 19 Embodiment 20 Catalyst volume ratio in 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 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] It can be seen from the data in Tables 3-1 to 3-4 that, compared with the reaction results shown in Comparative Example 1, the method for improving the space utilization of an alkane dehydrogenation reactor provided by the present invention has a significantly higher ratio of catalyst to bed volume. Compared with the reaction results shown in Comparative Examples 2 and 3, by controlling the volume ratio of the core-shell structure heat storage material / catalyst within the range provided by the present invention, the reaction conversion rate and selectivity results are better. Compared with the reaction results shown in Comparative Example 4, by controlling the core-shell structure heat storage material / catalyst to be non-uniformly loaded within the range provided by the present invention, the reaction conversion rate and selectivity results are better. Compared with the reaction results shown in Comparative Example 5, by controlling the volume ratio of Al2O3 porcelain balls / core-shell structure heat storage material within the range provided by the present invention, the catalyst has a significantly higher ratio of bed volume.

[0151] Any numerical value mentioned in the present invention, if there is only an interval of two units between any minimum value and any maximum value, includes all values ​​from the minimum value to the maximum value each time increasing by one unit. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, time, etc. is declared to be 50-90, in this specification it means that 51-89, 52-88... and 69-71 and 70-71 are specifically listed. For non-integer values, 0.1, 0.01, 0.001 or 0.0001 can be appropriately considered as a unit. These are just some specially 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 used to explain the present invention and do not constitute any limitation to 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 words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A method for improving the space utilization of an alkane dehydrogenation reactor, characterized in that: It includes adding thermal storage material to the reactor catalyst bed; The heat storage material comprises a core-shell structure heat storage material and Al2O3 porcelain balls; the core-shell structure heat storage material comprises a high temperature resistant shell and a metal alloy core; the volume ratio of the total amount of the Al2O3 porcelain balls to the total amount of 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.

2. The method according to claim 1, characterized in that The high temperature resistant shell is an inert metal oxide, preferably, selected from alumina, α-alumina, γ-alumina, silica, alumina and silica.

3. The method according to claim 1 or 2, characterized in that: The metal alloy core is an aluminum alloy, preferably selected from aluminum-magnesium alloy and cast aluminum alloy; the melting point of the metal alloy core is 500-650°C, preferably 560-620°C.

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 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.

5. The method according to any one of claims 1 to 4, characterized in that: The heat storage material and the catalyst are distributed in sections in the catalyst bed; 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 two adjacent 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, preferably (0.05-0.5):

1.

6. The method according to any one of claims 1 to 5, characterized in that: The catalyst is a catalyst containing at least one metal of Cr or Pt.

7. A method for dehydrogenating alkanes to produce light olefins, characterized in that: The method comprises filling the reactor catalyst bed with the method for improving the space utilization of the alkane dehydrogenation reactor according to any one of claims 1 to 6, and introducing one or more alkanes selected from propane, normal butane and isobutane for dehydrogenation reaction to produce light olefins.

8. The method for preparing light olefins by dehydrogenating alkanes according to claim 7, characterized in that: The dehydrogenation reaction temperature is 550-650°C, the pressure is 20-100 kPa, and the reaction gas mass space velocity is 0.4-2 hr -1 .

9. The method for dehydrogenating alkanes to prepare light olefins according to claim 7 or 8, characterized in that: The method comprises: setting 3 to 10 parallel alkane dehydrogenation reactors, and producing light olefins by alternately reacting, purging, regenerating, evacuating and reducing.

10. The method for preparing light olefins by dehydrogenating alkanes according to any one of claims 7 to 9, characterized in that: The regeneration is carried out by air regeneration, and the temperature of the regeneration air used is 600-700°C.

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