Regeneration method of catalyst for preparing olefin through alkane dehydrogenation

Abstract

The invention relates to the field of catalyst regeneration, and discloses a regeneration method of a catalyst for preparing olefin through alkane dehydrogenation, and the method comprises the following steps: (1) carrying out first charring on a spent catalyst in a charring zone of a first regenerator; (2) performing second charring on the product obtained in the step (1) in a charring area of a second regenerator to obtain a regenerated catalyst; wherein the pressure of the charring area of the second regenerator is 0.01-0.3 MPa higher than that of the charring area of the first regenerator. According to the method, the regeneration efficiency of the catalyst is improved, the problem of activity reduction caused by difficult removal of deposited carbon of the catalyst is solved, and the operation cycle of the device is prolonged.

Description

Technical Field

[0001] The invention relates to the field of catalyst regeneration, and in particular to a method for regenerating an alkane dehydrogenation catalyst to produce olefins. Background Art

[0002] Propylene is an important organic chemical raw material used to produce polypropylene, acrylonitrile, butanol, octanol, propylene oxide, isopropanol and other products. Traditional propylene mainly comes from the by-product of steam cracking to produce ethylene, and isobutylene almost all comes from refinery gas and cracking C4 fractions. With the increasing demand for propylene and isobutylene in the petrochemical industry, the traditional sources of propylene and isobutylene cannot meet the market demand. With the maturity of shale gas mining technology, a large amount of high-quality and cheap propane and butane are provided to the market. The process of direct catalytic dehydrogenation of alkanes to produce propylene and isobutylene is increasingly recognized by the market because of its economic and environmentally friendly technology. The process of dehydrogenating low-carbon alkanes to produce low-carbon olefins is mainly divided into moving bed process and fixed bed process. The fixed bed process reaction system design is relatively simple, but because the catalyst needs to be regenerated frequently, the switching operation is very frequent, and the control system, valves and equipment have high requirements. The moving bed process can realize the continuous regeneration and circulation of the catalyst, so that the catalyst remains in a high activity state, which can significantly improve the activity of the catalyst and ensure the yield of propylene.

[0003] In existing moving bed low-carbon alkane dehydrogenation industrial devices, the "core coke" phenomenon is very easy to occur, that is, the carbon deposits deep in the catalyst pores cannot be completely removed during the coking process. On the one hand, this is because the carbon deposits on the dehydrogenation catalyst are deep dehydrogenation products with low H / C, which are more difficult to remove; on the other hand, during the regeneration process of the catalyst, it is difficult for oxygen molecules to enter the deep pores, making it difficult to remove the carbon deposits deep in the pores. Studies have shown that increasing the regeneration oxygen partial pressure can effectively increase the diffusion rate of oxygen molecules, which is conducive to the entry of oxygen molecules into the deep pores, thereby accelerating the catalyst decarbonization rate. However, too high an oxygen content can easily cause regeneration overheating, which is not conducive to the operation of the device. Therefore, the most effective method is to increase the regeneration pressure.

[0004] However, during the combustion process, carbon deposits on the catalyst will produce a certain amount of water. Under high-pressure regeneration conditions, the water partial pressure will also increase accordingly. If the catalyst is in a high-temperature and high-water environment for a long time, it will seriously damage the catalyst pore structure and affect the catalyst performance. Therefore, the water in the regeneration circulating flue gas must be removed. However, the chlorine in the circulating flue gas will also be removed during the water removal process, making it difficult to suppress the metal aggregation on the catalyst surface in a high-temperature and low-chlorine environment, and will also affect the subsequent catalyst chlorine replenishment and metal redispersion effects.

[0005] CN112569872A discloses a moving bed system for preparing light olefins by dehydrogenation of light alkanes. Its technical solution includes: a raw material pretreatment unit, a fuel separation unit, a moving bed reaction unit, a hydrogen separation unit, a product purification unit, a product separation and purification unit and a catalyst regeneration unit connected in sequence through pipelines; the moving bed reaction unit includes a plurality of reaction pipelines arranged in parallel, and a heating furnace and a reactor are installed on the reaction pipelines.

[0006] CN1100852C discloses a method and equipment for regenerating a hydrocarbon conversion catalyst. The catalyst to be regenerated passes through the charring zone, oxychlorination zone, pre-drying zone and roasting zone of the regenerator from top to bottom in sequence. The additional pre-drying zone can use the regenerated circulating gas that has been dechlorinated and dried for pre-drying the catalyst after oxychlorination, thereby reducing the amount of dry gas used in the roasting zone, so that the amount of oxygen-containing gas entering the roasting zone is determined by the oxygen consumption required for charring. The gas entering the roasting zone can all enter the oxychlorination zone and then enter the regeneration gas circulation loop to supply oxygen for charring, so that there is no excess oxygen-containing gas to be vented in the calcining zone of the regenerator, thereby eliminating the purification measures for the vented gas in the calcining zone.

[0007] CN110452085A discloses a countercurrent moving bed C3 / C4 alkane dehydrogenation process, in which the flow direction of the catalyst between the reactors is opposite to the flow direction of the reactant flow. The method includes the mixed hydrogen and C3 / C4 alkane feed flowing through a heat combined heat exchanger and a heating furnace, entering the first-stage reactor, and flowing through the second-stage and the last-stage reactors in series to form a reactant flow; the catalyst is regenerated by a regenerator, entering the last-stage reactor, and flowing through the second-stage and the first-stage reactors in series to form a catalyst flow, and each reactor outlet has a hydrogen permeable membrane separator. Compared with the existing industrialized propane dehydrogenation process, it can improve the single-pass conversion rate of C3 / C4 alkanes, reduce the reaction temperature, improve selectivity, save energy, reduce carbon deposition on the catalyst, extend the life of the catalyst, and reduce the investment in the device.

[0008] US9302261B2 discloses a method for providing cooling air to a CCR cooling zone and preventing condensation in the cooler, wherein the method uses regenerated circulating air to heat a portion of the airflow from the cooler blower through a heat exchanger, and then mixes the heated airflow with the airflow entering the cooler, so that the temperature of the cooling airflow entering the cooler is not less than 4°C, and then cools the cooling air. The cooling air entering the cooling zone uses heated dry gas, which is a mixture of air and nitrogen.

[0009] CN105498858B discloses a method for regenerating a continuous reforming catalyst, wherein the catalyst to be regenerated after the reaction is passed into a regenerator, and sequentially passes through a charring zone, an oxychlorination zone and a calcination zone, and part of the regenerated gas discharged from the charring zone is directly injected into the oxychlorination zone, and a chlorine-containing compound is injected into the inlet gas flow of the charring zone, and the amount of chlorine injected is 0.01-0.2% by mass of the catalyst circulation amount in terms of chlorine element. This method can improve the catalyst regeneration effect and reduce the amount of chlorine injected during the regeneration process.

[0010] Although the above technologies have made some progress in optimizing low-carbon alkane dehydrogenation catalysts and processes, how to effectively solve the decline in catalyst activity caused by "core coke" is a technical problem that needs to be solved urgently. Summary of the invention

[0011] The purpose of the present invention is to overcome the problems existing in the prior art in the high-pressure regeneration process, such as the difficulty in replenishing chlorine to the catalyst and the poor subsequent metal redispersion effect caused by the water-chlorine imbalance in the circulating flue gas, and the problem of "core coke" caused by the difficulty of oxygen molecules entering deep into the catalyst pores in the low-pressure regeneration process. A regeneration method for an alkane dehydrogenation to olefin catalyst is provided, which improves the catalyst regeneration efficiency, solves the problem of activity reduction caused by the difficulty in removing catalyst carbon deposition, and prolongs the operation cycle of the device.

[0012] In order to achieve the above object, the present invention provides a method for regenerating an alkane dehydrogenation to olefin catalyst, the method comprising the following steps:

[0013] (1) performing a first charring of the catalyst to be regenerated in a charring zone of a first regenerator;

[0014] (2) subjecting the product obtained in step (1) to a second charring in a charring zone of a second regenerator to obtain a regenerated catalyst;

[0015] Among them, the pressure of the burning zone of the second regenerator is 0.01-0.3MPa higher than the pressure of the burning zone of the first regenerator.

[0016] Preferably, the dew point of the regeneration gas in the charring zone of the second regenerator is ≤-50°C, preferably ≤-60°C.

[0017] Preferably, the Cl2 content in the first burnt regeneration gas is 1-500vppm, preferably 100-300vppm.

[0018] Preferably, the HCl content in the second charred regeneration gas is ≤0.5 vppm.

[0019] Through the above technical solution, the following beneficial effects are obtained:

[0020] (1) The regeneration method provided by the present invention optimizes the regeneration system, overcomes the problems existing in high-pressure and low-pressure regeneration systems, improves the conversion rate of low-carbon alkanes and the catalyst regeneration efficiency, and realizes continuous circulation of the catalyst;

[0021] (2) In the present invention, preferably, chloride or chlorine is introduced into the burning zone of the first regenerator with a lower pressure, which can effectively alleviate the chlorine loss and metal aggregation of the catalyst during the burning process, and is beneficial to the subsequent metal redispersion process; in the burning zone of the second regenerator with a higher pressure, the oxygen partial pressure is effectively increased, the catalyst burning rate is accelerated, and the "core coke" problem caused by the difficulty of oxygen molecules to enter the deep pores of the catalyst is effectively solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the light alkane dehydrogenation process of the method of the present invention;

[0023] Figure 2 The present invention is a schematic diagram of the regeneration process of the spent catalyst in the method.

[0024] Description of Reference Numerals

[0025] Figure 1

[0026] Ⅰ-first reactor Ⅱ-second reactor Ⅲ-third reactor

[0027] IV-Fourth reactor 101 / 102 / 103 / 104 / 105-Pipeline 110-Heating furnace

[0028] 121-first reactor I upper reduction tank 122 / 125 / 128 / 132 / 144-lifter 123 / 126 / 129 / 133 / 145-lifting pipeline 124-second reactor II upper hopper 127-third reactor III upper hopper 130-fourth reactor IV upper hopper

[0029] 131-No.1 lock hopper 141-catalyst separation hopper 142-flow control area

[0030] 143-gas isolation zone 200-lock hopper No. 2 300-first regenerator 301-second regenerator

[0031] Figure 2

[0032] 201-Supplementary gas in high pressure area 202-Exhaust gas outside high pressure area 203-Regulating gas in balance area 204-Exhaust gas outside low pressure area 205-Exhaust gas outside No. 2 lock hopper

[0033] 302-Scorched zone of the first regenerator 303-Scorched zone of the second regenerator 304-Cooling transition zone

[0034] 305-Oxychlorination zone 306-Drying zone 311 / 314 / 315 / 320-Electric heater

[0035] 312 / 317- fan 313- first coke regeneration air 316- dryer and dechlorinator cooling

[0036] 318- Second coke regeneration gas air cooling 319- Cooler 321 / 322 / 323 / 324 / 326 / 327 / 328 / 329 / 330 / 331 / 332 / 334 / 337 / 340- Pipeline 341 / 342 / 343- Oxygen-containing gas 325 / 336- Chlorination agent-containing gas 333- Cooling transition zone gas 335 / 339- Mixed gas 350- Partition DETAILED DESCRIPTION

[0037] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0038] In one aspect, the present invention provides a method for regenerating an alkane dehydrogenation to olefin catalyst, the method comprising the following steps:

[0039] (1) performing a first charring of the catalyst to be regenerated in a charring zone of a first regenerator;

[0040] (2) subjecting the product obtained in step (1) to a second charring in a charring zone of a second regenerator to obtain a regenerated catalyst;

[0041] Among them, the pressure of the burning zone of the second regenerator is 0.01-0.3MPa higher than the pressure of the burning zone of the first regenerator.

[0042] In the present invention, by optimizing the regeneration system, a first regenerator and a second regenerator are provided, and the pressure of the burning zone of the second regenerator is adjusted to be higher than that of the burning zone of the first regenerator. The burning zone of the first regenerator is a low-pressure, low-oxygen, humid and hot environment, which can remove most of the carbon deposits while inhibiting the loss of chlorine and metal aggregation of the catalyst, thereby avoiding the difficulty of catalyst chlorine replenishment and poor subsequent metal redispersion effect caused by the imbalance of water and chlorine in the circulating flue gas in the high-pressure regeneration process.

[0043] In the present invention, preferably, the dew point of the regeneration gas in the charring zone of the first regenerator is greater than 0°C.

[0044] In the present invention, the catalyst to be regenerated after the first charring enters the second regenerator through pressure conversion, and the method of the pressure conversion is not particularly limited. Those skilled in the art can control the pressure of the charring zone of the second regenerator to be 0.01-0.3MPa higher than the pressure of the charring zone of the first regenerator. According to a preferred embodiment of the present invention, the pressure conversion is performed in a lock hopper.

[0045] In the present invention, compared with the existing low-pressure regeneration process and the high-pressure regeneration process used for continuous reforming, the regeneration method provided improves the conversion rate of low-carbon alkanes and the catalyst regeneration efficiency, realizes continuous circulation of the catalyst, solves the problem of activity decline caused by the difficulty in removing catalyst carbon deposition, and extends the operation cycle of the device.

[0046] According to the present invention, preferably, the pressure of the burning zone of the second regenerator is 0.15-0.3MPa higher than that of the burning zone of the first regenerator. In the present invention, the burning zone of the second regenerator is a high-pressure, high-oxygen, dry and cold environment, which can accelerate the removal of carbon deposits in the catalyst pores and effectively solve the "core coke" problem. In the present invention, the core coke refers to the phenomenon that in the low-pressure regeneration process, the burning is not thorough because oxygen molecules find it difficult to enter the deep catalyst pores.

[0047] The catalyst to be regenerated in the present invention has a common definition in the art, and the present invention has no particular limitation thereto. As long as the reaction performance is lower than that of a fresh catalyst, it can be used as the catalyst to be regenerated in the present invention, for example, a catalyst whose reaction activity or selectivity cannot meet the requirements and needs to be regenerated.

[0048] The spent catalyst of the present invention may be a spent catalyst from different catalytic fields, and is preferably a spent catalyst obtained by dehydrogenation of light alkanes.

[0049] According to the present invention, preferably, the spent catalyst comprises a carrier, an active component and carbon.

[0050] According to the present invention, preferably, the carbon content of the spent catalyst is 1-5% by mass, preferably 1-3% by mass, based on the total amount of the carrier and the active component.

[0051] According to the present invention, preferably, the carrier is selected from at least one of alumina, silica and zirconia, preferably alumina, and more preferably θ-alumina.

[0052] According to the present invention, preferably, the active component comprises a platinum group metal, an IVA group metal, an alkali metal and chlorine.

[0053] According to the present invention, preferably, the platinum group metal is platinum and / or palladium, preferably platinum.

[0054] According to the present invention, preferably, the Group IVA metal is selected from at least one of silicon, germanium and tin, preferably tin.

[0055] According to the present invention, preferably, the alkali metal is selected from at least one of potassium, sodium and rubidium, preferably potassium.

[0056] According to the present invention, preferably, based on the total amount of the carrier, the content of the platinum group metal is 0.1-1 mass %; the content of the IVA group metal is 0.1-1 mass %; the content of the alkali metal is 0.5-2 mass %; and the content of chlorine is 0.4-2 mass %.

[0057] In the present invention, preferably, the platinum group metal is platinum, and the content of the platinum group metal is 0.1-1% by mass based on the total amount of the carrier.

[0058] In the present invention, preferably, the IVA group metal is tin, and the content of the IVA group metal is 0.1-1% by mass based on the total amount of the carrier.

[0059] In the present invention, preferably, the alkali metal is potassium, and the content of the alkali metal is 0.5-2% by mass based on the total amount of the carrier.

[0060] In the present invention, preferably, the chlorine content is 0.5-1.5% by mass based on the total amount of the carrier.

[0061] The method provided by the present invention is particularly suitable for the regeneration of the above-mentioned catalyst. By regenerating the above-mentioned catalyst using the method provided by the present invention, the regenerated catalyst has the characteristics of high conversion rate and high selectivity. By using the method of the present invention, the conversion rate of low-carbon alkanes and the catalyst regeneration efficiency are improved, and the problem of decreased catalyst activity caused by incomplete burning is effectively solved.

[0062] According to the present invention, preferably, the dew point of the regeneration gas in the charring zone of the second regenerator is ≤-50° C., preferably ≤-60° C. Controlling the dew point of the regeneration gas to meet the above conditions can reduce the influence of water molecules on the regeneration of the catalyst to be regenerated, and reduce the aggregation of catalyst metal grains and rapid loss of specific surface area caused by excessive water content.

[0063] In the present invention, preferably, the pressure of the second char is higher than that of the first char, the inlet temperature of the regeneration gas of the second char is higher than that of the first char, and the oxygen content in the regeneration gas of the second char is higher than that in the regeneration gas of the first char.

[0064] According to the present invention, preferably, the first coking conditions include: the regeneration gas inlet temperature is 450-550°C, preferably 460-500°C; the pressure is 0.001-0.1MPa, preferably 0.01-0.1MPa; the oxygen content in the regeneration gas is 0.1-1.2v%, preferably 0.8-1.2v%; the gas-agent volume ratio is 1000-10000, preferably 2000-5000; the residence time is 1-5 hours, preferably 2-4 hours.

[0065] In the present invention, the first charring is carried out under the above conditions, so that most of the carbon deposits on the outer surface and external pores of the catalyst can be removed.

[0066] In the present invention, the charring zone of the first regenerator produces circulating gas, and the circulating gas can be discharged from the system or circulated to the charring zone of the first regenerator for use. According to the present invention, preferably, the method further comprises: discharging part of the circulating gas produced in the charring zone of the first regenerator from the system, and returning part of the circulating gas to the charring zone of the first regenerator after heat exchange and supplementing the chlorine-containing gas and the oxygen-containing gas. In this preferred embodiment, the circulating gas produced in the charring zone of the first regenerator supplements the chlorine-containing gas and the oxygen-containing gas to provide at least part of the first regeneration gas.

[0067] In the present invention, the chlorinating agent-containing gas is introduced into the coking zone of the first regenerator with a lower pressure, which can effectively alleviate the chlorine loss and metal aggregation of the catalyst during the coking process, and is beneficial to the subsequent metal redispersion process.

[0068] According to the present invention, preferably, the chlorinating agent is Cl2 and / or an organic chloride.

[0069] In the present invention, the mass of Cl element supplemented in the charred zone of the first regenerator is not particularly limited, as long as the Cl2 content in the first charred regenerator is 1-500vppm. Preferably, the mass of Cl element supplemented in the charred zone of the first regenerator is 0.01-0.2% of the flow rate of the catalyst to be regenerated. The mass of Cl element supplemented in the charred zone of the first regenerator is the mass of Cl element additionally supplemented by the chlorinating agent-containing gas.

[0070] In the present invention, the flow rate of the catalyst to be generated can be adaptively adjusted by those skilled in the art according to the reaction conditions.

[0071] According to the present invention, preferably, the Cl2 content in the first charred regeneration gas is 1-500 vppm, preferably 100-300 vppm. The Cl2 content in the first charred regeneration gas refers to the Cl2 content in the charring zone of the first regenerator when the first charring is performed. The first charring is performed using the first charred regeneration gas, which can effectively remove carbon deposits on the outer surface and external pores of the catalyst, and alleviate the phenomenon of metal aggregation during the catalyst regeneration process.

[0072] According to the present invention, preferably, the second coking conditions include: the regeneration gas inlet temperature is 500-600°C, preferably 520-560°C; the pressure is 0.06-0.3MPa, preferably 0.1-0.3MPa; the oxygen content in the regeneration gas is 1.2-5v%, preferably 2-4v%; the gas-agent volume ratio is 1000-10000, preferably 3000-6000; the residence time is 1-5 hours, preferably 2-4 hours.

[0073] In the present invention, the second charring is carried out under the above conditions, which can effectively remove the carbon deposits deep in the catalyst pores.

[0074] According to the present invention, preferably, the HCl content in the second charred regeneration gas is ≤0.5 vppm. Controlling the HCl content in the second charred regeneration gas to ≤0.5 vppm can effectively control the chlorine content of the catalyst, thereby avoiding the increase of catalyst acidity and side reactions due to high chlorine content of the catalyst.

[0075] According to the present invention, preferably, the method further comprises: partially discharging the circulating gas generated in the charring zone of the second regenerator from the system, and partially returning the circulating gas to the charring zone of the second regenerator after heat exchange, dechlorination, drying, and supplementation with oxygen-containing gas.

[0076] In the present invention, the second regenerator includes a charring zone, a cooling transition zone, an oxychlorination zone and a drying zone of the second regenerator. The operating conditions of each zone are not particularly limited, and those skilled in the art can make adaptive adjustments according to the catalyst regeneration conditions in the second regenerator. Preferably, the temperature of the cooling transition zone is 200-480°C, the temperature of the oxychlorination zone is 120-600°C, and the temperature of the drying zone is 120-600°C.

[0077] In the present invention, preferably, part of the circulating gas generated in the charring zone of the second regenerator is heat exchanged in a cooler, cooled to 350-460° C., and enters a cooling transition zone.

[0078] In the present invention, preferably, oxygen-containing gas is supplemented in the coking zone of the second regenerator. The coking zone of the second regenerator has a high pressure, and supplementing oxygen-containing gas can effectively increase the oxygen partial pressure, accelerate the catalyst coking rate, and remove the carbon deposits that are difficult to burn in the pores of the catalyst to be regenerated, thereby effectively solving the "core coke" problem caused by the difficulty of oxygen molecules entering the deep pores of the catalyst.

[0079] According to a preferred embodiment of the present invention, the spent catalyst after the second charring is cooled, oxychlorinated and dried.

[0080] According to a preferred embodiment of the present invention, the cooling is carried out in the cooling transition zone, and after cooling, the catalyst enters the oxychlorination zone, and the catalyst is oxychlorinated with a chlorinating agent gas, and the platinum group metal redispersion performance of the catalyst is adjusted with a high-temperature mixed gas, the mixed gas includes an oxygen-containing gas and a protective gas, preferably air and nitrogen. The temperature of the mixed gas is 400-600°C.

[0081] In the present invention, preferably, the spent catalyst is dried in a drying zone, and the moisture generated by the second charring is removed in the drying zone to ensure good performance of the spent catalyst.

[0082] In the present invention, the regenerated catalyst obtained by the regeneration method provided by the present invention has better performance.

[0083] According to the present invention, preferably, the method further comprises: the regenerated catalyst is contacted with a low-carbon alkane to carry out a dehydrogenation reaction.

[0084] The present invention has no particular limitation on the type of reactor for carrying out the dehydrogenation reaction, and any reactor conventionally used in the art may be used.

[0085] In the present invention, preferably, the regenerated catalyst is reduced from an oxidized catalyst to a reduced catalyst before undergoing a dehydrogenation reaction.

[0086] According to a preferred embodiment of the present invention, the dehydrogenation reaction is carried out in a moving bed reaction zone, preferably the moving bed reaction zone comprises at least 2 radial moving bed reactors connected in series, more preferably 4-5 radial moving bed reactors connected in series, and a heating furnace is arranged in front of each reactor. Preferably, the regenerated catalyst first enters a gas isolation zone, the gas isolation zone converts the oxygen environment into a hydrogen environment, and is lifted to the upper reduction tank of the first reactor I through a lifter, the oxidized catalyst is reduced to a reduced catalyst in the upper reduction tank of the first reactor I, and enters the first reactor I to participate in the dehydrogenation reaction, completing the circulation, regeneration and reduction of the catalyst.

[0087] According to the present invention, preferably, the product of the dehydrogenation reaction includes at least one of hydrogen, alkanes and olefins.

[0088] According to the present invention, preferably, the low carbon alkane is a C2-C4 alkane. Preferably, the content of C3 alkane in the low carbon alkane is greater than 95% by volume. The low carbon alkane comes from at least one of refinery by-products, shale gas and oil field associated gas.

[0089] In the present invention, the conditions of the dehydrogenation reaction can be adaptively adjusted by those skilled in the art according to the needs of the dehydrogenation reaction. According to a preferred embodiment of the present invention, the conditions of the dehydrogenation reaction include: a temperature of 550-700°C, preferably 600-650°C; a pressure of 0.01-0.5MPa, preferably 0.01-0.2MPa; a hydrogen-to-hydrocarbon volume ratio of 0.2-2, preferably 0.4-0.7; a mass space velocity of 0.1-10h -1 , preferably 0.3-4h -1 .

[0090] According to a preferred embodiment of the present invention, the catalyst to be regenerated generated by the dehydrogenation reaction flows out from the bottom of the fourth reactor, and the dust in the catalyst is separated through the catalyst separation hopper. At the top of the catalyst separation hopper, the elutriation gas from the dust removal fan blows a small amount of dust in the catalyst to be regenerated out from the top of the catalyst separation hopper, and the dust and the elutriation gas are separated in the dust collector. The separated elutriation gas is pressurized and recycled. The catalyst to be regenerated after elutriation enters the pressure conversion and flow control area under the action of gravity, completing the pressure conversion of the catalyst to be regenerated from the low-pressure reactor to the high-pressure regenerator, and then enters the first regenerator from the top.

[0091] According to a preferred embodiment of the present invention, the light alkane dehydrogenation process is as follows: Figure 1 As shown, the regeneration process of the spent catalyst is as follows Figure 2 As shown. After heat exchange, the low-carbon alkane enters the heating furnace 110 through pipeline 101 for heating, and then enters the first reactor I for dehydrogenation reaction. The effluent of the first reactor I enters the heating furnace 110 through pipeline 102 for heating and then enters the second reactor II. The effluent of the second reactor II enters the heating furnace 110 through pipeline 103 for heating and then enters the third reactor III. The effluent of the third reactor III enters the heating furnace 110 through pipeline 104 for heating and then enters the fourth reactor IV. The product of the fourth reactor IV enters the product fractionation system through pipeline 105 for separation. Part of the hydrogen distilled out is used as a product discharge device, and part is circulated to the reaction zone as circulating hydrogen; olefins are used as product discharge devices; unconverted alkanes are returned to the reaction zone for refining.

[0092] According to a preferred embodiment of the present invention, the regenerated catalyst is reduced to a reduced catalyst in the reduction tank 121 at the top of the first reactor I, enters the first reactor I to participate in the dehydrogenation reaction, is lifted to the top hopper 124 of the second reactor II through the lifter 122 and the lifting pipeline 123, enters the second reactor II, and passes through the lifter 125, the lifting pipeline 126, the top hopper 127 of the third reactor III, the third reactor III, the lifter 128, the lifting pipeline 129, the top hopper 130 of the fourth reactor IV, and the fourth reactor IV in sequence. The catalyst to be regenerated flows out from the bottom of the fourth reactor IV, passes through the catalyst collector (not shown), passes through the No. 1 lock hopper 131, the lifter 132, and the lifting pipeline 133, enters the catalyst separation hopper 141, and enters the first regenerator 300 after passing through the flow control area 142.

[0093] According to a preferred embodiment of the present invention, Figure 2 As shown, the catalyst to be regenerated undergoes a first charring treatment in the charring zone 302 of the first regenerator, and the circulating gas of the charring zone 302 of the first regenerator is discharged from the pipeline 321, a small part of which is discharged from the system through the pipeline 322, and the rest enters the fan 312. After heat exchange by the first charred regeneration gas air cooling 313, it is fully mixed with the supplementary oxygen-containing gas 343 and the chlorination agent-containing gas 325 through the pipeline 324, and is sent to the electric heater 311. The outlet temperature of the electric heater 311 is controlled to be 400-600°C, and is returned to the entrance of the charring zone 302 of the first regenerator through the pipeline 326.

[0094] The catalyst to be regenerated after the first charring treatment enters the No. 2 lock hopper 200 for pressure increase, and the low-pressure gas discharged is discharged to the outside exhaust 204, part of which is discharged as the No. 2 lock hopper outside exhaust 205, and part of which is returned to the No. 2 lock hopper 200 as the balance zone adjustment gas 203, and the high-pressure zone supplementary gas 201 is introduced for further pressurization, and the high-pressure zone outside exhaust 202 is discharged. After the pressure increase is completed, it enters the second regenerator 301, and the catalyst to be regenerated passes through the partition 350, the charring zone 303 of the second regenerator, the cooling transition zone 304, the oxychlorination zone 305 and the drying zone 306 from top to bottom. The second charring is carried out in the charring zone 303 of the second regenerator, and the circulating gas of the charring zone 303 of the second regenerator is discharged from the pipeline 327, a small part of which is discharged from the system through the pipeline 328, and part of it enters the fan 317, and the oxygen-containing gas 341 is divided into oxygen-containing gas 342 and oxygen-containing gas 343. The circulating gas entering the fan 317 enters the second charring regeneration gas air cooling 318 through the pipeline 329, and then enters the pipeline 330 to be fully mixed with the oxygen-containing gas 342, and then is sent to the dryer and dechlorinator 316. After the water and chlorine in the circulating gas are removed, part of it is used as the cooling transition zone gas 333 through the pipeline 331, and the rest enters the electric heater 314 to be heated to 400-600℃, and returns to the charring zone 303 of the second regenerator through the pipeline 332.

[0095] The second charred catalyst flows to the cooling transition zone 304, and the gas 333 in the cooling transition zone is cooled to 350-450°C by the cooler 319, and then enters the cooling transition zone 304 through the pipeline 334. The mixed gas 335 contains a certain amount of nitrogen and air, which is heated to 400-600°C by the electric heater 320, fully mixed with the chlorinating agent gas 336, and enters the oxychlorination zone 305 through the pipeline 337.

[0096] The mixed gas 339 is heated to 400-600°C by the electric heater 315 and sent to the drying zone 306 through the pipeline 340. The dried regenerated catalyst flows out from the bottom of the second regenerator 301, enters the gas isolation zone 143, and is lifted to the upper reduction tank 121 of the first reactor I by the lifter 144, completing the circulation of the catalyst to be regenerated.

[0097] According to a particularly preferred embodiment of the present invention, a method for regenerating an alkane dehydrogenation to olefin catalyst comprises the following steps:

[0098] (1) performing a first charring of the catalyst to be regenerated in a charring zone of a first regenerator;

[0099] (2) subjecting the product obtained in step (1) to a second charring in a charring zone of a second regenerator to obtain a regenerated catalyst;

[0100] Among them, the pressure of the burnt zone of the second regenerator is 0.15-0.3MPa higher than that of the burnt zone of the first regenerator;

[0101] The dew point of the regeneration gas in the charring zone of the second regenerator is ≤-60°C;

[0102] The Cl2 content in the first charred regeneration gas is 100-300vppm;

[0103] The HCl content in the second charred regeneration gas is ≤0.5vppm.

[0104] The present invention will be described in detail below through examples and comparative examples. In the following examples and comparative examples, unless otherwise specified, the reagents and materials used can be obtained commercially;

[0105] The carbon content in the catalyst is tested by a high-frequency infrared carbon-sulfur analyzer;

[0106] The Cl2 content in the first charred regeneration gas was measured by ion chromatography;

[0107] The HCl content in the second charred regeneration gas is measured by the detection tube method.

[0108] Catalyst A Preparation Example

[0109] (1) Preparation of composite carrier

[0110] Take 54g of aluminum flakes, add 610g of hydrochloric acid solution with a concentration of 18% by mass, dissolve the aluminum flakes, and obtain a solution with an aluminum chloride content of 4% by mass. The aluminum chloride solution is transferred to a neutralization tank, 850g of ammonia water with a concentration of 6% by mass is added, mixed evenly at 60°C, and the pH value is 7.5-8.5. The generated aluminum hydroxide is filtered and washed, and 9mL of nitric acid with a volume ratio of 1:1 is added to the filter cake to acidify to obtain a sol. Under stirring, 40mL of a solution containing 30g of urea and a hydrochloric acid solution containing 0.32g of tin are added to the sol, so that the Sn content in the solution is 0.32% by mass of dry aluminum oxide, and stirred for 1 hour for acidification. Then, 30g of kerosene and 3g of fatty alcohol polyoxyethylene ether are added dropwise to the acidified sol under stirring. The sol is dripped into an oil-ammonia column with an upper layer of oil phase and a lower layer of ammonia phase to form a ball. The oil phase is kerosene, and the concentration of ammonia in the ammonia phase is 8% by mass. The wet bulb was solidified in an ammonia aqueous phase for 1 hour, taken out and rinsed with deionized water, dried at 60°C for 6 hours, dried at 120°C for 10 hours, calcined in an air flow at 650°C for 4 hours, then treated at 650°C in air with a water vapor content of 5% by volume for 10 hours, and then heated to 1000°C for a second calcination for 4 hours to obtain a tin-containing θ-A12O3 carrier a.

[0111] (2) Preparation of Catalyst A

[0112] Take the above-mentioned tin-containing θ-A12O3 carrier a, and impregnate it with an impregnation solution containing chloroplatinic acid and hydrochloric acid at 25°C for 4 hours. The impregnation solution contains 0.30% by mass of platinum and 2.0% by mass of chlorine (both relative to dry alumina), and the liquid / solid ratio is 1.8mL / g. The solid obtained after impregnation is dried at 120°C for 12 hours and calcined at 500°C for 4 hours. The calcined solid is then impregnated with a potassium nitrate solution at 25°C for 4 hours. The potassium nitrate solution contains 1% by mass of potassium (relative to dry alumina), and the liquid / solid ratio is 1.4mL / g. The solid obtained after impregnation is dried at 120°C for 12 hours and calcined at 600°C for 4 hours. The calcined catalyst is reduced with hydrogen at 550°C for 2 hours to obtain catalyst A.

[0113] Example 1

[0114] according to Figure 1 The schematic diagram of the alkane dehydrogenation process is shown in Figure 2. Figure 2 The schematic diagram of the regeneration process of the spent catalyst shown in the figure is to carry out a dehydrogenation reaction of the light alkane raw materials shown in Table 1 in the presence of catalyst A.

[0115] Table 1 Composition of low carbon alkanes

[0116]

[0117]

[0118] After heat exchange, the low-carbon alkane feedstock enters the heating furnace 110 through pipeline 101 for heating, and then enters the first reactor I for dehydrogenation reaction. The effluent of the first reactor I enters the heating furnace 110 through pipeline 102 for heating and then enters the second reactor II. The effluent of the second reactor II enters the heating furnace 110 through pipeline 103 for heating and then enters the third reactor III. The effluent of the third reactor III enters the heating furnace 110 through pipeline 104 for heating and then enters the fourth reactor IV. The product of the fourth reactor IV enters the product fractionation system through pipeline 105 for separation. The inlet temperatures of the first to fourth reactors are controlled to be 615°C, 636°C, 637°C, and 633°C, respectively, the hydrogen-to-hydrocarbon volume ratio is 0.53, the inlet pressures of the first to fourth reactors are 0.186MPa, 0.135MPa, 0.086MPa, and 0.039MPa, respectively, and the total mass space velocity is 3h -1 The carbon content in the spent catalyst was 1.5% by mass.

[0119] Catalyst A enters the first reactor I to participate in the dehydrogenation reaction, is lifted to the upper hopper 124 of the second reactor II through the lifter 122 and the lift pipeline 123, enters the second reactor II, and sequentially passes through the lifter 125, the lift pipeline 126, the upper hopper 127 of the third reactor III, the third reactor III, the lifter 128, the lift pipeline 129, the upper hopper 130 of the fourth reactor IV, and the fourth reactor IV, and is converted into a catalyst to be produced.

[0120] The catalyst to be regenerated flows out from the bottom of the fourth reactor IV, passes through the catalyst collector (not shown), through the No. 1 lock hopper 131, the lift 132, and the lifting pipeline 133, enters the catalyst separation hopper 141, and enters the first regenerator 300 after passing through the flow control area 142.

[0121] The first charring is carried out in the charring zone 302 of the first regenerator. The conditions of the first charring include: the regeneration gas inlet temperature is 480°C, the pressure is 0.01MPa, the oxygen content in the regeneration gas is 0.9v%, the gas-agent volume ratio is 3500:1, and the residence time is 3.5 hours. The circulating gas of the charring zone 302 of the first regenerator is discharged from the pipeline 321, a small part is discharged from the system through the pipeline 322, and the rest enters the fan 312. After the first charring regeneration gas air cooling 313 heat exchange, it is fully mixed with the supplementary oxygen-containing gas 343 through the pipeline 324 and the chlorination agent-containing gas 325. The flow rate of the catalyst to be regenerated is 300kg / h, the mass of the supplementary Cl element is 0.54kg / h, and the Cl2 content in the first charring regeneration gas is 160vppm. The circulating gas is sent to the electric heater 311, and the outlet temperature of the electric heater 311 is controlled to be 480°C, and it returns to the entrance of the charring zone 302 of the first regenerator through the pipeline 326.

[0122] The catalyst to be regenerated after the first charring treatment enters the No. 2 lock hopper 200, is pressurized, and the low-pressure gas is discharged as the No. 2 lock hopper external exhaust 204, part of which is discharged as the No. 2 lock hopper external exhaust 205, and part of which is returned to the No. 2 lock hopper 200 as the balance zone adjustment gas 203, and the high-pressure zone supplementary gas 201 is introduced for further pressurization, and the high-pressure zone external exhaust 202 is discharged. After the pressure is increased, it enters the second regenerator 301, and the catalyst to be regenerated passes through the partition 350, the charring zone 303 of the second regenerator, the cooling transition zone 304, the oxychlorination zone 305 and the drying zone 306 from top to bottom. The second charring is carried out in the charring zone 303 of the second regenerator. The conditions of the second charring include: the regeneration gas inlet temperature is 530°C, the pressure is 0.3MPa, the oxygen content in the regeneration gas is 2.5v%, the gas-agent volume ratio is 5000:1, and the residence time is 3 hours.

[0123] The circulating gas of the charring zone 303 of the second regenerator is discharged from pipeline 327, a small part of which is discharged from the system through pipeline 328, and part of which enters the fan 317. The oxygen-containing gas 341 is divided into oxygen-containing gas 342 and oxygen-containing gas 343. The circulating gas entering the fan 317 enters the second charring regeneration gas air cooling 318 through pipeline 329, and then enters pipeline 330 to be fully mixed with oxygen-containing gas 342, and then sent to the dryer and dechlorinator 316. After the water and chlorine in the circulating gas are removed, part of it is used as cooling transition zone gas 333 through pipeline 331, and the rest enters the electric heater 314 to be heated to 530°C, and returns to the charring zone 303 of the second regenerator through pipeline 332. The dew point of the charring zone of the second regenerator is -60°C.

[0124] The second charred catalyst flows to the cooling transition zone 304. The gas 333 in the cooling transition zone is cooled to 460°C by the cooler 319 and then enters the cooling transition zone 304 through the pipeline 334. The mixed gas 335 contains a certain amount of nitrogen and air, which is heated to 540°C by the electric heater 320, fully mixed with the chlorinating agent gas 336, and enters the oxychlorination zone 305 through the pipeline 337. The chlorine injection amount in the oxychlorination zone is 2.7 kg / h on average. The mixed gas 339 is heated to 560°C by the electric heater 315 and sent to the drying zone 306 through the pipeline 340. The dried regenerated catalyst flows out from the bottom of the second regenerator 301, enters the gas isolation zone 143, is lifted to the upper reduction tank 121 of the first reactor I by the lifter 144, enters the first reactor I to participate in the dehydrogenation reaction, and completes the circulation of the catalyst to be regenerated. The reaction time is 24 hours from the time when the reactor is filled with oil.

[0125] Example 2

[0126] According to the method of Example 1, dehydrogenation of light alkanes and regeneration of the spent catalyst are carried out, except that the pressure of the burning zone of the second regenerator is changed to be 0.09 MPa higher than that of the burning zone of the first regenerator. The rest is the same as Example 1.

[0127] Example 3

[0128] According to the method of Example 1, the dehydrogenation of light alkanes and the regeneration of the spent catalyst are carried out, except that the dew point of the regeneration gas in the charring zone of the second regenerator is -40°C. The rest is the same as Example 1.

[0129] Example 4

[0130] According to the method of Example 1, the dehydrogenation of light alkanes and the regeneration of the spent catalyst are carried out, except that the Cl2 content in the first burnt regeneration gas is 70vppm, and the rest is the same as Example 1.

[0131] Example 5

[0132] According to the method of Example 1, the dehydrogenation of light alkanes and the regeneration of the spent catalyst are carried out, except that the Cl2 content in the first burnt regeneration gas is 340 vppm, and the rest is the same as Example 1.

[0133] Example 6

[0134] According to the method of Example 1, dehydrogenation of light alkanes and regeneration of spent catalyst are carried out, except that the HCl content in the second charred regeneration gas is 2 vppm, and the rest is the same as Example 1.

[0135] Comparative Example 1

[0136] Dehydrogenation of light alkanes and regeneration of the catalyst to be regenerated are carried out according to the method of Example 1, except that the second regenerator is not set up, and a first burning zone and a second burning zone are set up in the first regenerator. The pressure of the first burning zone and the second burning zone is 0.01 MPa, and the rest is the same as Example 1.

[0137] Comparative Example 2

[0138] Dehydrogenation of light alkanes and regeneration of the catalyst to be regenerated are carried out according to the method of Example 1, except that the second regenerator is not set up, and a first burning zone and a second burning zone are set up in the first regenerator. The pressure of the first burning zone and the second burning zone is 0.3 MPa, and the rest is the same as Example 1.

[0139] The regeneration results of the spent catalysts of the examples of the present invention and the comparative examples are shown in Table 2.

[0140] The metal dispersion is measured by hydrogen chemisorption method.

[0141] Table 2 Regeneration results of spent catalyst

[0142]

[0143] Note: (1)Randomly select 100 regenerated catalysts, cut them open and observe the "core coke" condition. If black spots appear inside the regenerated catalysts, it means "core coke" condition has occurred. Record the results.

[0144] It can be seen from the results in Table 2 that the regeneration method of the present invention has a low carbon content in the regenerated catalyst, no "core coke" phenomenon, and high metal dispersion. The regenerated catalyst obtained by the regeneration method of Comparative Example 1 has a "core coke" ratio of up to 16% and a high carbon content. The regenerated catalyst obtained by the regeneration method of Comparative Example 2 has a low carbon content but a low metal dispersion.

[0145] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for regenerating an alkane dehydrogenation to olefin catalyst, characterized in that: The method comprises the following steps: (1) performing a first charring of the catalyst to be regenerated in a charring zone of a first regenerator; (2) subjecting the product obtained in step (1) to a second charring in a charring zone of a second regenerator to obtain a regenerated catalyst; Among them, the pressure of the burning zone of the second regenerator is 0.01-0.3MPa higher than the pressure of the burning zone of the first regenerator.

2. The method according to claim 1, wherein: The pressure in the burnt zone of the second regenerator is 0.15-0.3MPa higher than that in the first regenerator.

3. The method according to claim 1 or 2, wherein: The catalyst to be produced comprises a carrier, an active component and carbon; Preferably, the carbon content of the spent catalyst is 1-5% by mass, preferably 0.1-3% by mass, based on the total amount of the carrier and the active component; Preferably, the carrier is selected from at least one of alumina, silicon oxide and zirconium oxide, preferably alumina; Preferably, the active component comprises a platinum group metal, a Group IVA metal, an alkali metal and chlorine; Preferably, based on the total amount of the carrier, the content of the platinum group metal is 0.1-1 mass %; the content of the IVA group metal is 0.1-1 mass %; the content of the alkali metal is 0.5-2 mass %; and the content of chlorine is 0.4-2 mass %.

4. The method according to any one of claims 1 to 3, wherein: The dew point of the regeneration gas in the coking zone of the second regenerator is ≤-50°C, preferably ≤-60°C.

5. The method according to any one of claims 1 to 4, wherein: The first coking conditions include: the regeneration gas inlet temperature is 450-550°C, preferably 460-500°C; the pressure is 0.001-0.1MPa, preferably 0.01-0.1MPa; the oxygen content in the regeneration gas is 0.1-1.2v%, preferably 0.8-1.2v%; the gas-to-agent volume ratio is 1000-10000, preferably 2000-5000; the residence time is 1-5 hours, preferably 2-4 hours.

6. The method according to any one of claims 1 to 5, wherein: The method further comprises discharging part of the circulating gas generated in the charring zone of the first regenerator out of the system, and returning part of the circulating gas to the charring zone of the first regenerator after heat exchange and supplementation with chlorinating agent gas and oxygen-containing gas; Preferably, the chlorinating agent is Cl2 and / or an organic chloride.

7. The method according to any one of claims 1 to 6, wherein: The second coking conditions include: the regeneration gas inlet temperature is 500-600°C, preferably 520-560°C; the pressure is 0.06-0.3MPa, preferably 0.1-0.3MPa; the oxygen content in the regeneration gas is 1.2-5v%, preferably 2-4v%; the gas-to-agent volume ratio is 1000-10000, preferably 3000-6000; the residence time is 1-5 hours, preferably 2-4 hours.

8. The method according to any one of claims 1 to 7, wherein: The Cl2 content in the first charred regeneration gas is 1-500vppm, preferably 100-300vppm; And / or, the HCl content in the second charred regeneration gas is ≤0.5vppm.

9. The method according to any one of claims 1 to 8, wherein: The method further comprises: partially discharging the circulating gas generated in the charring zone of the second regenerator from the system, and partially returning the circulating gas to the charring zone of the second regenerator after heat exchange, dechlorination, drying, and supplementation with oxygen-containing gas.

10. The method according to any one of claims 1 to 9, wherein: The method further comprises: contacting the regenerated catalyst with light alkanes to carry out a dehydrogenation reaction; Preferably, the low carbon alkane is a C2-C4 alkane; Preferably, the conditions for the dehydrogenation reaction include: a temperature of 550-700°C, preferably 600-650°C; The pressure is 0.01-0.5MPa, preferably 0.01-0.2MPa; the volume ratio of hydrogen to hydrocarbon is 0.2-2, preferably 0.4-0.7; Mass space velocity is 0.1-10h -1 , preferably 0.3-4h -1 .

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