Moving bed propane dehydrogenation conversion process method and reaction system

Abstract

The invention relates to a process method and a reaction system for propane dehydrogenation conversion in a moving bed, which belong to the field of petrochemical industry, and the process method comprises the following steps: preheating a propane raw material gas, in the presence of hydrogen, enabling the preheated propane raw material gas to sequentially pass through reaction zones (2-6 zones) of a downstream moving bed partition reactor in a countercurrent manner, and enabling the preheated propane raw material gas to pass through downstream moving bed reactors which are connected in series in a parallel (smooth) manner; the method comprises the following steps: under the reaction conditions that the temperature is 500-700 DEG C, the pressure is 0.01-3 MPa and the volume space velocity is 0.3-5 h <-1 >, carrying out a contact reaction with a gamma-aluminum oxide / theta-aluminum oxide composite carrier pellet catalyst which is loaded with platinum, tin, potassium, chlorine and phosphorus and has the diameter of 1.5-2 mm, and separating converted gas into a subsequent device to obtain propylene, the carbon deposition deactivated catalyst enters a regenerator, nitrogen containing oxygen and chlorine is introduced, and charring, oxychlorination and reduction regeneration are carried out at 500-700 DEG C. According to the continuous reaction-regeneration process and the reaction system, the dehydrogenation conversion efficiency can be improved, devices and equipment are simplified, coking, energy consumption, investment and occupied area are reduced, and the operability and operation stability of the process are improved.

Description

Technical Field

[0001] This invention relates to a process and reaction system for propane dehydrogenation conversion using a moving bed reactor; more specifically, this invention relates to a process and reaction system employing a downflow moving bed partitioned reactor and a series downflow moving bed reactor to achieve propane dehydrogenation conversion; it belongs to the field of petrochemical technology. Background Technology

[0002] Propylene is the second most important basic raw material in the petrochemical industry after ethylene. It can be used to synthesize polypropylene, polyacrylonitrile, acrolein, acrylic acid, propylene oxide, isopropanol, cumene, propylene oligomers, etc., and is widely used in various industries such as materials, pharmaceuticals, and textiles.

[0003] Currently, common technologies for producing propylene include catalytic cracking, steam cracking, olefin breakdown, olefin disproportionation, methanol-to-olefins (MTO), and propane dehydrogenation. Propylene production via propane dehydrogenation offers advantages such as high product yield and good selectivity, and is therefore receiving increasing attention, with the number of industrial-scale plants steadily growing.

[0004] The main industrial methods for propane dehydrogenation include the Oleflex process from UOP (Universal Oil Products), the Catofin process from ABB Lummus, the STAR process from Uhde, the PDH process from Linde / BASF, and the FBD process from Snamprogetti / Yarsintez. These are described in standards such as USP3978150, USP4926005, CA113133048, DE3841800, and GB2177317A. Catalysts are classified as platinum-based and chromium-based, as described in USP4827066, GB1168342A, USP02956030, and CN113244907A.

[0005] The Oleflex process is a moving-bed continuous regeneration reaction process that achieved industrial production in 1990 and has been applied in most propane dehydrogenation to propylene projects both domestically and internationally. The advantages of this process include continuous operation, uniform load, high space velocity, and a propylene yield of up to 85% (USP 3584060, USP 3878131, USP 4438238, USP 4595673, USP 4716143, USP 4786265, USP 4827072). The Oleflex process uses a platinum catalyst, which can be recycled through isothermal regeneration (USP 4778942, USP 6756340, etc.).

[0006] CN112074499A discloses a dehydrogenation method and reaction system, wherein the moving bed reactor includes a heat exchanger containing a heating medium, the catalyst material and the heating medium are not in contact, and more than half of the enthalpy change in at least one reaction zone is provided by the heat exchanger; the hydrocarbon feed reacts with the catalyst in at least one reaction zone of the moving bed reactor to convert into products containing olefins, alkynes, cyclic hydrocarbons and / or aromatics.

[0007] CN110452085A discloses a moving bed C3 / C4 alkane dehydrogenation process, in which the catalyst flows in the opposite direction to the reactant stream between reactors. The method includes a mixed hydrogen and C3 / C4 alkane feed stream passing through a combined heat exchanger and a furnace, entering the first-stage reactor, and then sequentially flowing through the second and final-stage reactors to form the reactant stream. The catalyst is regenerated in a regenerator and enters the final-stage reactor, then sequentially flowing through the second and first-stage reactors to form the catalyst feed stream. Each reactor outlet is equipped with a hydrogen permeation membrane separator. Compared with existing industrialized processes, this method can improve single-pass conversion and selectivity, reduce reaction temperature to save energy, reduce carbon buildup and extend reactor life, and reduce investment.

[0008] CN116020356A also discloses a method and system for dehydrogenation of low-carbon alkanes in a countercurrent moving bed, comprising introducing low-carbon alkanes from the inlet of a dehydrogenation reaction zone to engage in countercurrent contact with a dehydrogenation catalyst; the dehydrogenation reaction zone containing at least two reactors connected in series so that a gaseous stream can pass through each reactor sequentially; obtaining a precursor catalyst from the upstream reactor; regenerating and reducing the precursor catalyst sequentially to obtain a regenerated catalyst; recycling the regenerated catalyst back to the downstream reactor; and introducing sulfur-containing coking inhibitors into each reactor to ensure stable operation of the apparatus.

[0009] CN116693360A discloses a method involving a dehydrogenation reaction of low-carbon alkanes with a catalyst in a reaction apparatus under hydrogen-bearing and anhydrous conditions. When the carbon content of the dehydrogenation catalyst at the outlet of the upstream moving bed reactor falls within the range of 1 wt% to 1.8 wt%, it enters a regeneration unit for regeneration. The catalyst is an alumina-supported active component consisting of platinum, tin, and rare earth elements, which improves conversion rate, selectivity, and product yield.

[0010] CN115612519A discloses a novel regeneration method and system for a moving bed low-carbon alkane dehydrogenation catalyst, comprising a catalytic dehydrogenation reaction unit, a dust removal unit, a carbonization and chlorination unit, a reduction unit, an activation unit, and a tail gas purification unit connected sequentially by pipelines; after dust removal, the deactivated catalyst flows to the carbonization and chlorination unit to remove carbon deposits, and is then sent to the reduction unit for reduction and activation to improve olefin selectivity.

[0011] CN111170821A also discloses a propane dehydrogenation process involving catalyst regeneration and dual online switching of reactors, including a catalytic dehydrogenation process and a catalyst regeneration process. The feedstock exchanges heat with the product gas flowing out of the last-stage reactor in a heat exchanger, and then enters the reactor after being heated in a heater. Each stage reactor is equipped with an intermediate heater. The process gas is heated to the reaction temperature in the heater and enters the next stage reactor. The last-stage reactor has two reactors, one operating and one standby, which can be freely switched. The product gas flowing out of the last-stage reactor exchanges heat with the feedstock, is then cooled, and subsequently enters a separation system to separate and obtain the final product, propylene. The catalyst to be regenerated after participating in the reaction in the last-stage reactor is collected by a catalyst collector and then subjected to panning and coking to obtain regenerated catalyst. The regenerated catalyst then enters each stage reactor sequentially to participate in the reaction, achieving recycling.

[0012] CN114570437A also discloses a method for removing sulfur from a catalyst during propane dehydrogenation in a moving bed. Propane is introduced into the reaction zone of the moving bed and contacts the propane dehydrogenation catalyst. The propane dehydrogenation reaction is carried out at 580–650 °C. The sulfur-containing spent catalyst flowing out of the reaction zone enters the regeneration zone, where it undergoes coking and oxychlorination to obtain a regenerated catalyst. The regenerated catalyst is then sent to the reduction zone, where hydrogen gas containing 0.02 vol%–0.8 vol% water vapor is introduced. The regenerated catalyst is reduced and desulfurized at 500–600 °C, thereby improving the catalyst's reaction performance.

[0013] Improving the performance of catalysts in moving bed dehydrogenation processes is a crucial issue in the development of propane dehydrogenation to propylene technology. Current technologies suffer from problems such as insufficient conversion efficiency, demanding reaction conditions, high operational complexity, uneven catalyst performance, severe coking, high energy consumption, and frequent shutdowns. Ensuring the full and balanced effective utilization of catalyst activity in processes with multiple moving bed reactors, as well as effectively suppressing coking and controlling side reactions, are important research areas. Reducing the use of precious metals and energy consumption, and simplifying reactors, equipment systems, processes, and operational complexity, are all significant for cost reduction, facilitating stable process operation, and improving operability and economics. Summary of the Invention

[0014] Propane dehydrogenation is a strongly endothermic, reversible reaction involving an increase in the number of molecules. High temperature and low pressure favor the dehydrogenation reaction. The main chemical reactions involved include the propane dehydrogenation main reaction, hydrocarbon cracking and coking reactions, and side reactions that produce other products. The typical reaction temperature is around 600℃. At such high temperatures, propane cracking and deep dehydrogenation are intensified, reducing propylene selectivity. Simultaneously, it exacerbates carbon deposition on the catalyst surface, leading to rapid catalyst deactivation. Continuous or intermittent regeneration is necessary to restore its activity.

[0015] In propane dehydrogenation, moving bed reactors allow for continuous reaction-regeneration without interruption. To maintain the required conversion rate, multiple moving bed reactors are often used in series. In this case, the catalysts in each reactor (zone) are at different activity levels. The propane dehydrogenation conversion process requires the catalyst and process to maintain stable and efficient conversion performance under harsh reaction conditions, while the reaction-regeneration process should be simple and easy to operate. Balancing and maintaining good catalyst activity matching in each reactor (zone), coordinating external preheating and internal heat supplementation, addressing insufficient heat, suppressing coking and side reactions, and maintaining good reaction selectivity are crucial for improving the conversion efficiency, operability, and stable operation of the dehydrogenation reaction process.

[0016] The purpose of this invention is to obtain a stable and efficient propane dehydrogenation conversion method, which further balances and promotes the activity of the catalyst in the moving bed propane dehydrogenation conversion process, maintains a high conversion rate, solves the problems of insufficient heat and heat supply imbalance, coordinates the external preheating and internal heat supplementation of multiple moving bed reactors, solves the problems of effective contact between reactants and catalysts, easy transportation and high-efficiency heat transfer, minimizes the harshness of the reaction conversion process, suppresses side reactions and coking rate, and improves the operability and operational stability of the process and equipment.

[0017] Specifically, in order to achieve the above-mentioned objectives of this invention, the technical solution and the invention content are as follows:

[0018] The present invention provides a moving bed propane dehydrogenation conversion process, characterized in that it includes:

[0019] (1) After the propane feed gas is heated to 300-600°C in a preheating furnace, it enters the reactor from the bottom of the downflow moving bed zone (2-6 reaction zones) reactor at a hydrogen / hydrocarbon volume ratio of (0.1-6):1, and comes into countercurrent contact with the catalyst that comes from the series downflow moving bed reactor after the reaction, which enters from the top port of the reactor.

[0020] (2) The reacted material coming out of the top of the partitioned reactor is heated to 300-500°C and then enters from the top of the series-connected downward moving bed reactor, and comes into parallel (co-)flow contact with the regenerated catalyst from the regenerator that enters from the top port.

[0021] (3) The dehydrogenation conversion reaction in the two reactors was carried out at a temperature of 500–680 °C, a pressure of 0.01–1 MPa, and a volume hourly space velocity of 0.1–2 h⁻¹. -1 Under certain conditions, the catalyst reacts with 1.5–2 mm diameter γ-alumina microspheres loaded with platinum, tin, potassium, chlorine, and phosphorus. The product gas after the reaction conversion enters the subsequent separation unit.

[0022] (4) The deactivated catalyst from the lower port of the partitioned reactor enters from the upper port of the moving bed regenerator, and nitrogen containing oxygen and chlorine is introduced. It is then subjected to coking and oxychlorination at 500-700°C, and reduced by contact with hydrogen at 500-600°C. The catalyst then exits from the lower port of the regenerator and enters the reaction-regeneration process of the next cycle.

[0023] The present invention provides a moving bed propane dehydrogenation conversion process, characterized in that the catalyst is a high-pore-volume macroporous γ-alumina and θ-alumina composite support microsphere with a pore size of 3-25 nm, the γ-alumina / θ-alumina mass ratio is 1:(0.1-10), and it is loaded with 0.3wt%-0.6wt% platinum, 0.3wt%-0.5wt% tin, 0.1-1.3wt% potassium, 0.3-1.5wt% chlorine and 0.1wt%-0.5wt% phosphorus based on the total amount of oven-dry catalyst. The catalyst has a specific surface area of ​​95-120 m² / g, a pore volume of 0.5-0.9 mL / g, a bulk density of 0.5-0.7 mL / g, a diameter of 1.6-1.8 mm, and a crushing strength of 45-65 N / particle.

[0024] The present invention provides a moving bed propane dehydrogenation conversion process, characterized in that the catalyst regeneration coking and oxychlorination process is carried out at 510-650°C with nitrogen gas containing 0.1%-8% oxygen and 0.05%-1.0% chlorine, reducing the carbon content of the catalyst from 1.2%-3% before regeneration to 0.01%-0.2% after regeneration.

[0025] The process method for propane dehydrogenation conversion in a moving bed provided by the present invention is characterized in that the oxygen-containing element comes from oxygen in the air added to nitrogen, and the chlorine-containing element comes from tetrachloroethylene and / or dichloroethane compounds added to nitrogen.

[0026] The present invention provides a process for the dehydrogenation conversion of propane in a moving bed, characterized in that the reduction process of the regenerated catalyst is to contact hydrogen containing 0.02v% to 0.8v% water at 510 to 570°C for 1 to 6 hours.

[0027] The present invention also provides a reaction system for implementing the moving bed propane dehydrogenation conversion process, characterized in that it includes propane (1) as reactant, platinum-tin composite alumina microsphere dehydrogenation catalyst, a downward moving bed partitioned reactor (4) in countercurrent contact with the catalyst, a downward moving bed series reactor (8) in parallel (co-current) contact with the catalyst, a moving bed regenerator (30), a feed preheating furnace (9) for the partitioned reactor, a feed heating furnace (10) for the series reactor, and a high-temperature heat medium for heating the partitioned reactor. Furnace (11), zoned reactor zone (5-7) and heat exchange coils and grate plates for supplementary heating (29), heat exchangers (3) for propane reaction feedstock (1) and conversion product gas (2), catalyst lifting hopper (12-14), transfer hopper (15-17), lock hopper (18-19), catalyst nitrogen sealing tank (20), material conveying pipeline (27), catalyst conveying pipeline (28), fan, pump, gas-solid separator, hydrogen separator, dust separator and collector.

[0028] In the reaction system of the moving bed propane dehydrogenation conversion process provided by the present invention, the upper part of the countercurrent downward moving bed partition reactor (4), the parallel downward moving bed series reactor (8), and the moving bed regenerator (30) each includes a catalyst buffer hopper (21-22), a separation hopper (23), and a sealed feed leg; the lower part of each includes a feed leg, a catalyst collection hopper (24-26), and a catalyst flow controller.

[0029] In the reaction system of the moving bed propane dehydrogenation conversion process provided by the present invention, the high-temperature heat medium in the heat exchange coil (29) of the internal component of the partitioned reactor (4) is selected from molten nitrates, chlorides and caustic alkalis, and the working temperature range is 550 to 900°C.

[0030] The present invention also provides the steps of the reaction material flow when implementing the moving bed propane dehydrogenation conversion process and reaction system, characterized in that: the reaction material flow (1) exchanges heat with the reaction product (2) through the heat exchanger (3), is heated by the preheating furnace (9), and enters the reactor from the bottom of the partitioned moving bed reactor (4), and sequentially ascends to the reaction zone (5-7) inside the reactor; the heating furnace (11) heats the high-temperature heat medium in the coil (29) separating the reaction zone, and supplements the heat required for the dehydrogenation reaction in the reaction zone (5-7) through heat exchange; after the reaction conversion product comes out from the top of the partitioned reactor (4), it is separated by hydrogen separator, and then heated again by the heating furnace (10), and descends from the top of the series moving bed reactor (8) into the reactor; after the reaction product comes out from the bottom of the reactor, it is separated by hydrogen separator, enters the heat exchanger (3) to exchange heat with the fresh reaction material flow (1), and then enters the subsequent separation device for separation.

[0031] The present invention also provides the steps of the catalyst feed flow when implementing the moving bed propane dehydrogenation conversion process and reaction system, characterized in that: the regenerated catalyst exiting the regenerator (30) is lifted by hydrogen from the regenerated catalyst lift hopper (12) to the catalyst transfer hopper (15) of the series moving bed reactor (8); it flows down through the catalyst buffer hopper (21) into the series moving bed reactor (8), and passes through the discharge leg and the catalyst collection hopper (24); it enters the catalyst transfer hopper (16) of the partitioned reactor through the catalyst lift hopper (14), and passes through the discharge leg and the buffer hopper of the partitioned reactor. (22) The catalyst flows down into the reaction zone (7, 6, 5) of the partitioned reactor (4) in sequence, and then down into the catalyst collection hopper (25) via the discharge leg; it passes through the lock hopper (18) and the catalyst lifting hopper (13), and then into the catalyst transfer hopper (17). It then passes through the regenerator separation hopper (23) and the discharge leg, and then down into the regenerator (30) and the regenerated catalyst collection hopper (26). Finally, it passes through the discharge leg, the catalyst cooling flow controller, the regenerated catalyst nitrogen sealing tank (20), and the lock hopper (19), and then into the regenerated catalyst lifting hopper (12), thus forming a complete cycle of catalyst material flow.

[0032] The materials, chemicals, and reagents involved in the propane dehydrogenation conversion process and reaction system provided by this invention, as well as the commercially available unit equipment and apparatus, can be easily obtained through commercial purchase. The conventional chemical operation processes involved in the propane dehydrogenation conversion process and reaction system of this invention are well known to those skilled in the art and are used in daily research and production processes.

[0033] The beneficial effects of the moving bed propane dehydrogenation conversion process and reaction system of the present invention are as follows:

[0034] This invention employs a countercurrent downflow moving bed zoned reactor and a series parallel (co-current) downflow moving bed reactor, combined with a platinum-tin composite alumina dehydrogenation catalyst modified with metal and non-metal elements and a moving bed regenerator. This results in a more rational distribution of the catalytic activity of the regenerated catalyst in each reactor (zone), a more balanced control of dehydrogenation conversion and coking rates, and more coordinated and sufficient preheating and internal heat replenishment of the reactor. This reduces preheating temperature and coking in the heater furnace, forming a high-efficiency, stable, continuous reaction-regeneration process and reaction system. This improves propane dehydrogenation conversion efficiency, simplifies the reactor, internal components, and equipment system, reduces downtime and cumbersome maintenance, reduces floor space and investment, and improves catalyst delivery, process operability, operational stability, and economy. Attached Figure Description

[0035] See attached document Figure 1Further description of the content, implementation methods, and effects of this invention will make other features, objectives, and advantages of this application clearer, but this does not limit the broad interpretation of this invention. Figure 1 This is a schematic flow diagram illustrating a moving bed propane dehydrogenation conversion process and reaction system according to the present invention.

[0036] Figure 1 In the diagram: 1-Propane (raw material); 2-Product gas; 3-Heat exchanger; 4-Countercurrent downflow moving bed reactor; 5-7-Reaction zones of the reactor (example of reaction zone 3); 8-Series parallel (co-current) downflow moving bed reactor; 9-Preheater for the reactor; 10-Feed heater for the series reactor; 11-High-temperature heat medium heater; 12-14-Catalyst lifting hopper; 15-17-Catalyst transfer hopper; 18-19-Closed hopper; 20-Catalyst nitrogen sealing tank; 21-22-Catalyst buffer hopper; 23-Regenerator separation hopper; 24-26-Catalyst collection hopper; 27-Material conveying pipeline; 28-Catalyst conveying pipeline; 29-High-temperature heat medium heat exchange coil; 30-Moving bed regenerator.

[0037] It should be noted that, for the purposes of brevity, clarity, and ease of description, the flowchart used to illustrate the present invention is provided. Figure 1 The present invention only shows the parts most relevant to the invention and does not list in detail the fans, pumps, catalyst cooling flow controllers, gas-solid separators, hydrogen separators, dust separators, collectors and subsequent separation processes that are also needed in the present invention, but this does not affect or limit the disclosure and interpretation of the present invention. Detailed Implementation

[0038] The following is in conjunction with the appendix Figure 1 The present invention will be further described in detail with reference to specific embodiments; it is understood that the specific embodiments and examples described herein are for illustrative purposes only and are not intended to limit the invention; features in the embodiments may be combined with each other unless otherwise specified.

[0039] The specific implementation of the moving bed propane dehydrogenation conversion process and reaction system of the present invention is as follows:

[0040] First, referring to the steps and contents disclosed in the Chinese patents applied for and granted by the inventor (see the examples listed), the spherical dehydrogenation catalyst of the present invention is prepared according to the content and calculations of the present invention.

[0041] propane dehydrogenation process :

[0042] After the propane reactant stream (1) exchanges heat with the reaction product (2) through the heat exchanger (3), it is heated by the preheating furnace (9) and enters the reactor from the bottom of the partitioned moving bed reactor (4). It then passes through the reaction zones 5, 6, and 7 inside the reactor in sequence. The catalyst that has been reacted and partially carbonized at the lower port of the series reactor enters the catalyst transfer hopper (16) of the partitioned reactor through the catalyst lifting hopper (14). After passing through the discharge leg and the buffer hopper (22) of the partitioned reactor, it descends into the reaction zones (7, 6, and 5) of the partitioned reactor (4) in sequence, and comes into countercurrent contact with the upward propane material to carry out the dehydrogenation conversion reaction. This also helps to loosen the partitioned catalyst bed and facilitates the downward movement of the small ball catalyst.

[0043] The heating furnace (11) heats the high-temperature heat medium in the coil (29) that separates the reaction zones, and replenishes the heat required for the dehydrogenation reaction in the reaction zones (5-7) through heat exchange. The grate plate and the coil (29) divide the partitioned reactor into 2-4 reaction zones. The reaction temperature of each reaction zone can be adjusted by the coil (29). Each reaction zone can use the same reaction temperature or different reaction temperatures.

[0044] After the dehydrogenation reaction product exits from the top of the partitioned reactor (4), hydrogen is separated by a hydrogen separator, and then reheated by a heater (10). It then descends from the top of the series moving bed reactor (8) and passes through the reactor interior. The regenerated catalyst exiting the regenerator (30) is lifted by hydrogen from the regenerated catalyst lift hopper (12) to the catalyst transfer hopper (15) of the series moving bed reactor (8). It then descends through the catalyst buffer hopper (21) into the series moving bed reactor (8), where it comes into contact with the conversion product gas exiting the partitioned reactor (4) in a parallel (co-current) flow to carry out the dehydrogenation reaction. After the parallel (co-current) contact reaction, the catalyst passes through the discharge leg and the catalyst collection hopper (24) and enters the lift hopper (14) and the partitioned reactor.

[0045] After the reaction product comes out from the bottom of the series reactor (8), hydrogen is separated by a hydrogen separator, and then it enters the heat exchanger (3) to exchange heat with the fresh reactant stream (1). After that, it enters the subsequent separation device for separation to obtain the product propylene.

[0046] Catalyst regeneration process :

[0047] The deactivated catalyst after the reaction in the partitioned reactor (4) is decomposed and enters the catalyst collection hopper (25) through the discharge leg; it enters the catalyst transfer hopper (17) through the lock hopper (18) and the catalyst lifting hopper (13); it enters the regenerator separation hopper (23) and the discharge leg through the regenerator (30) and the regenerated catalyst collection hopper (26); it enters the regenerated catalyst lifting hopper (12) through the discharge leg, the catalyst cooling flow controller, the regenerated catalyst nitrogen sealing tank (20), and the lock hopper (19) for cyclic reaction-regeneration.

[0048] The above description of specific embodiments of the present invention discloses the detailed steps and implementation of a moving bed propane dehydrogenation conversion process and reaction system.

[0049] In the following examples, the composition analysis of the feed gas and the converted gas was performed using an Agilent 6890N gas chromatograph; the analysis of the catalyst was performed according to the relevant analytical methods in "Analytical Methods for Petrochemical Products (RIPP Test Methods)" published by Science Press in 1990; other analytical tests can be found in "National Standards for Test Methods of Petroleum and Petroleum Products" published by China Standards Press in 1989.

[0050] Example

[0051] First, the desired platinum-tin composite alumina microsphere dehydrogenation catalyst was prepared according to the invention.

[0052] High-porosity macroporous γ-alumina was prepared according to the preparation steps and methods in the embodiments of the authorized Chinese patent CN113289673B and the published Chinese patent CN114988447A; θ-alumina was prepared according to the preparation steps and methods in the embodiments of the Chinese patent CN113751080A filed by the inventor; and the γ-alumina and θ-alumina composite carrier microspheres required by the present invention were prepared according to the alumina drop ball forming method in the authorized patent CN108273566B.

[0053] According to the preparation steps and methods in the authorized patent CN108435221B and the disclosed examples in CN111085199A, and in conjunction with the specific requirements for the catalyst in the claims and content of this invention, the platinum-tin composite alumina microsphere dehydrogenation catalyst required by this invention is prepared.

[0054] The calculated amounts of chloroplatinic acid, tin dichloride, and potassium chloride solution were impregnated onto the prepared γ-alumina microsphere support. After drying, the impregnated aluminum phosphate sol was sprayed onto the support and then calcined at 580°C for 6 hours to obtain a microsphere dehydrogenation conversion catalyst with platinum and tin as the dehydrogenation active components and modified by metal and non-metal elements.

[0055] The catalyst contains 0.3 wt% platinum, 0.4 wt% tin, 0.9 wt% potassium, 1.2 wt% chlorine, and 0.5 wt% phosphorus, based on the total amount of the dry catalyst. The catalyst has a specific surface area of ​​95 m² / g, a pore volume of 0.5 mL / g, a mesopore size range of 3.9–10 nm, a bulk density of 0.65 g / mL, and a strength of 55 N / particle.

[0056] A small-scale laboratory experimental setup was used to simulate the moving bed process of this invention for evaluation, illustrating the effectiveness of the process method and reaction system of this invention in propane dehydrogenation conversion. The platinum-tin composite alumina dehydrogenation catalyst prepared above was loaded into the dehydrogenation reactor, and industrial-grade propane was used as the reaction feedstock in the experiment, with a propane content of not less than 96 wt%. Propane feedstock and hydrogen were introduced to carry out the reaction conversion.

[0057] The reaction conditions were: a propane feedstock to hydrogen volume ratio of 1:0.6 and a volume hourly space velocity (VHSV) of 0.5 h⁻¹. -1 The pressure was 0.1 MPa and the temperature was 600℃. To simplify the experimental simulation process, propane feedstock and hydrogen were introduced into the lower section of reactors 1 to 3 in the pre-processing reactor for 20, 40, and 60 hours respectively to pre-deposit carbon, simulating the carbon deposition status of the catalyst in the three reaction zones of the partitioned reactor under actual industrial operation.

[0058] The No. 4 reactor, which is connected in series, uses a regenerated catalyst after carbon deposition and coking to simulate actual industrial operation. The regeneration conditions are as follows: nitrogen gas containing 5v% oxygen is introduced at 600°C for coking, followed by oxychlorination with a chlorinating agent until the carbon monoxide content in the tail gas is less than 0.1v%; then, it is reduced by contacting hydrogen gas containing 0.1v% water at 520°C for 2 hours. During the reaction, the raw material enters the reactor from the upper port of the No. 4 reactor.

[0059] Under the above reaction and regeneration test conditions, the total propylene yield was 85% after 100 hours of stable operation, and the propane single-pass conversion rate was 27%. Compared with existing mature industrial moving bed processes, under the premise of obtaining the same conversion results, carbon deposition was reduced by 25%–35%, energy consumption was reduced by 10%–15%, and the single-pass operation cycle was extended by 20%–25%. Furthermore, the number of reactors can be reduced from four to two, and the internal components of the reactors are greatly simplified, thereby simplifying operation, reducing equipment investment and floor space, and improving process efficiency.

[0060] Finally, the above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features.

[0061] Furthermore, it should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept; for example, technical solutions formed by replacing the above-mentioned features with technical features with similar functions disclosed in this application (but not limited to).

Claims

1. A process for the dehydrogenation conversion of propane in a moving bed, characterized in that, include: (1) After the propane feed gas is heated to 300-600°C in a preheating furnace, it enters the reactor from the bottom of the downflow moving bed partitioned (2-6 reaction zones) reactor at a hydrogen / hydrocarbon volume ratio of 0.1-6:1, and comes into countercurrent contact with the catalyst that comes from the series downflow moving bed reactor after the reaction, which enters from the top port of the reactor. (2) The reacted material coming out of the top of the partitioned reactor is heated to 300-500°C and then enters from the top of the series-connected downward moving bed reactor, and comes into parallel (co-current) contact with the regenerated catalyst from the regenerator that enters from the top port. (3) The dehydrogenation conversion reaction in the two reactors was carried out at a temperature of 500–680℃, a pressure of 0.01–1 MPa, and a volume hourly space velocity of 0.1–2 h⁻¹. -1 Under certain conditions, the catalyst is reacted with 1.5–2 mm diameter γ-alumina / θ-alumina composite supported microspheres loaded with platinum, tin, potassium, chlorine and phosphorus. The product gas after the reaction conversion enters the subsequent unit for separation to obtain propylene. (4) The deactivated catalyst from the lower port of the partitioned reactor enters from the upper port of the moving bed regenerator. Nitrogen gas containing oxygen and chlorine is introduced and coking and oxychlorination are carried out at 500-700°C. The catalyst is then reduced by contacting hydrogen at 500-600°C and exits from the lower port of the regenerator to enter the reaction-regeneration process of the next cycle.

2. The process method for moving bed propane dehydrogenation conversion according to claim 1, characterized in that, The catalyst is a high-pore-volume macroporous γ-alumina and θ-alumina composite support microsphere with a pore size of 3-25 nm, and a γ-alumina / θ-alumina mass ratio of 1:(0.1-10). It is loaded with 0.3wt%-0.6wt% platinum, 0.3wt%-0.5wt% tin, 0.1-1.3wt% potassium, 0.3-1.5wt% chlorine and 0.1wt%-0.5wt% phosphorus based on the total amount of oven-dry catalyst. The catalyst has a specific surface area of ​​95-120 m² / g, a pore volume of 0.5-0.9 mL / g, a bulk density of 0.5-0.7 mL / g, a diameter of 1.6-1.8 mm, and a crushing strength of 45-65 N / particle.

3. The process method for moving bed propane dehydrogenation conversion according to claim 1, characterized in that, The catalyst regeneration coking and oxychlorination process involves passing nitrogen gas with an oxygen content of 0.1%–8% and a chlorine content of 0.1%–1.0% at 510–650°C. This process reduces the carbon content of the catalyst from 1.2%–3% before regeneration to 0.01%–0.2% after regeneration.

4. The process method for moving bed propane dehydrogenation conversion according to claim 3, characterized in that, The oxygen-containing element comes from oxygen in the air added to nitrogen, and the chlorine-containing element comes from tetrachloroethylene and / or dichloroethane compounds added to nitrogen.

5. The process method for moving bed propane dehydrogenation conversion according to claim 1, characterized in that, The catalyst regeneration process involves contacting hydrogen containing 0.02v% to 0.8v% water at 510–570°C for 1–6 hours.

6. A reaction system for implementing the moving bed propane dehydrogenation conversion process according to any one of claims 1 to 5, characterized in that, The reactor includes propane (1) as reactant, platinum-tin composite alumina microsphere dehydrogenation catalyst, a downflow moving bed zone reactor (4) in countercurrent contact with the catalyst, a downflow moving bed series reactor (8) in parallel (co-current) contact with the catalyst, a moving bed regenerator (30), a feed preheating furnace (9) for the zone reactor, a feed heating furnace (10) for the series reactor, a high-temperature heat medium heating furnace (11) for the zone reactor, zone reactor zones (5-7) and high-temperature heat medium heat exchange coils and grate plates (29) for supplementary heating, a heat exchanger (3) for propane reaction feedstock (1) and conversion product gas (2), a catalyst lifting hopper (12-14), a transfer hopper (15-17), a lock hopper (18-19), a catalyst nitrogen sealing tank (20), a material conveying pipeline (27), a catalyst conveying pipeline (28), a fan, a pump, a gas-solid separator, a hydrogen separator, a dust separator, and a collector.

7. The reaction system of the moving bed propane dehydrogenation conversion process according to claim 6, characterized in that, The upper part of the countercurrent downflow moving bed partition reactor (4), the parallel flow downflow moving bed series reactor (8), and the moving bed regenerator (30) each includes a catalyst buffer hopper (21-22), a separation hopper (23), and a sealing hopper; the lower part each includes a discharge hopper, a catalyst collection hopper (24-26), and a catalyst flow controller.

8. The reaction system of the moving bed propane dehydrogenation conversion process according to claim 6, characterized in that, The high-temperature heat medium in the heat exchange coil (29) of the internal components of the partitioned reactor (4) is selected from molten nitrates, chlorides and caustic alkalis, and the working temperature range is 550 to 900°C.

9. A moving bed propane dehydrogenation conversion process and reaction system according to claims 1 and 6, characterized in that, The steps of the reaction material flow are as follows: the reaction material flow (1) exchanges heat with the reaction product (2) through the heat exchanger (3), is heated by the preheating furnace (9), and enters the reactor from the bottom of the partitioned moving bed reactor (4), and sequentially moves upward to the reaction zone (5-7) inside the reactor; the heating furnace (11) heats the high-temperature heat medium in the coil (29) that separates the reaction zone, and replenishes the heat required for the dehydrogenation reaction in the reaction zone (5-7) through heat exchange; after the reaction conversion product comes out from the top of the partitioned reactor (4), hydrogen is separated by the hydrogen separator, and then it is heated again by the heating furnace (10), and moves downward from the top of the series moving bed reactor (8) into the reactor; after the reaction product comes out from the bottom of the reactor, hydrogen is separated by the hydrogen separator, and then it enters the heat exchanger (3) to exchange heat with the fresh reaction material flow (1), and then enters the subsequent separation device for separation.

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