Method for regenerating dehydrogenation catalyst

Abstract

The invention relates to the technical field of petrochemical industry, and discloses a dehydrogenation catalyst regeneration method, which comprises: (1) carrying out first charring on a spent catalyst in a first-stage charring zone, and carrying out second charring on the spent catalyst in a second-stage charring zone; (2) enabling the product after the second charring to pass through a drying zone, an oxychlorination zone and a cooling zone to obtain a regenerated catalyst; wherein gases discharged from the first-section charring area, the second-section charring area and the oxychlorination area are respectively and independently circulated. According to the method, the drying area is arranged below the scorching area, so that independent circulation of gases in the scorching area and the oxychlorination area is realized, the noble metal dispersity of the low-carbon alkane dehydrogenation catalyst can be improved, and the regeneration effect of the catalyst is improved.

Description

Technical Field

[0001] The invention relates to the technical field of petrochemical engineering, and in particular to a regeneration method for a dehydrogenation catalyst. Background Art

[0002] Propylene is an important organic chemical raw material used to produce polypropylene, acrylonitrile, butanol, octanol, propylene oxide, isopropanol and other products. Traditionally, 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.

[0003] 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 are required to be high. The moving bed process can realize the continuous regeneration and circulation of the catalyst, keep the catalyst in a high active state, and can significantly improve the activity of the catalyst and ensure the yield of propylene.

[0004] During the regeneration process, the moving bed low-carbon alkane catalyst generally undergoes processes such as charring, redispersion of metal Pt, and reduction of oxidized metal. The redispersion effect of metal Pt is crucial to the reaction performance of the regenerated catalyst. The redispersion reaction process of metal Pt is as follows:

[0005] Metal + Cl2 + O2 → Oxidized / redispersed metal

[0006] In the redispersion process of metal Pt, high chlorine content and oxygen-rich environment are conducive to the redispersion of metal on the catalyst. However, in the existing process, the catalyst will carry some water when it flows down from the burnt zone, and the water will react with Cl2 in the oxychlorination zone as follows, resulting in enhanced catalyst acidity, which in turn affects the catalyst performance.

[0007] 2Cl2+H2O→4HCl+O2

[0008] At the same time, the existing process injects chloride into the oxychlorination zone in a "one-pass" form, which leads to problems such as increased chlorine injection during the regeneration process, increased risk of chlorine corrosion, and high chlorine content in the regeneration gas exhaust.

[0009] CN104107704B discloses a regeneration method for a platinum-containing low-carbon alkane dehydrogenation catalyst, and its technical scheme includes: using a gas flow containing 0.1-10 mol% O2 to perform carbonization treatment in stages, using a halogen-containing component to contact with a gas flow of H2O or a decomposable oxygen-containing compound to deactivate the catalyst and increase the halogen content of the catalyst; using a gas flow containing 1-10 mol% O2 to treat the catalyst to promote the redispersion of the active metal component Pt; and reducing the active metal component at 450-650° C. in a reducing atmosphere. The regeneration of the O2 is relatively large, the regeneration time is relatively long, and different gases need to be introduced at different stages of the staged carbonization treatment, and the operation is relatively complicated.

[0010] 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.

[0011] 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 stream, and the method includes the mixed hydrogen and C3 / C4 alkane feed flows through a heat combined heat exchanger and a heating furnace, enters a first-stage reactor, flows through a second-stage and a last-stage reactor in series to form a reactant stream; the catalyst is regenerated by a regenerator, enters a last-stage reactor, flows through a second-stage and a first-stage reactor in series to form a catalyst stream, and each reactor outlet has a hydrogen permeable membrane separator. This method mainly changes the flow direction of the catalyst, and there is no special improvement in the regeneration of the catalyst.

[0012] Therefore, for the spent catalyst after dehydrogenation of light alkanes, a catalyst regeneration method that can effectively remove carbon deposits, improve the dispersion of precious metals, and be easy to operate is needed. Summary of the invention

[0013] The purpose of the present invention is to overcome the problems of poor precious metal dispersion, difficult carbon deposition removal and poor regeneration effect after regeneration of a low-carbon alkane dehydrogenation catalyst in the prior art, and to provide a regeneration method for a dehydrogenation catalyst. The method places a drying zone below a charring zone to achieve independent circulation of gases in the charring zone and an oxychlorination zone, thereby improving the precious metal dispersion of the low-carbon alkane dehydrogenation catalyst and improving the regeneration effect of the catalyst.

[0014] In order to achieve the above object, the present invention provides a method for regenerating a dehydrogenation catalyst, wherein the method comprises:

[0015] (1) The spent catalyst is subjected to a first coking process in the first coking zone and then subjected to a second coking process in the second coking zone;

[0016] (2) passing the second charred product through a drying zone, an oxychlorination zone, and a cooling zone to obtain a regenerated catalyst;

[0017] The gases exhausted from the first-stage charring zone, the second-stage charring zone and the oxychlorination zone are circulated independently.

[0018] Preferably, the oxygen content in the regeneration gas of the first coking zone is 0.2-1% by volume, preferably 0.5-1% by volume.

[0019] Preferably, the oxygen content in the regeneration gas in the second-stage coking zone is 1-10% by volume, preferably 2-6% by volume.

[0020] Preferably, a chlorinating agent is also introduced into the oxychlorination zone, and the chlorinating agent is chlorine gas and / or an organic chloride.

[0021] Preferably, the chlorinating agent is mixed with the third circulating gas discharged from the oxychlorination zone and then circulated back to the oxychlorination zone.

[0022] Through the above technical solution, the beneficial effects obtained are as follows:

[0023] (1) The regeneration method provided by the present invention realizes independent circulation of the gases in the charring zone and the oxychlorination zone by placing the drying zone below the charring zone, and the oxychlorination zone is self-circulating, which can improve the dispersion of the precious metals in the low-carbon alkane dehydrogenation catalyst and improve the regeneration effect of the catalyst;

[0024] (2) In the present invention, preferably, the chlorine loss is reduced by self-circulation of the oxychlorination zone without external chlorine discharge, and the chlorine content in the circulating gas of the oxychlorination zone is ensured by reasonably adjusting the chlorine injection amount, and the chlorine injection amount is reduced;

[0025] (3) In the present invention, preferably, the oxygen content in the first and second burning zones is controlled to be different, and the carbon deposits on the catalyst to be regenerated are removed in a targeted manner without damaging the catalyst, with the carbon deposits being easy to burn and having a low carbonization degree and being difficult to burn having a high carbonization degree. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the process flow of dehydrogenation catalyst regeneration.

[0027] Description of Reference Numerals

[0028] Figure 1

[0029] 101, 116, 117, 120, 102-catalyst separation hopper 103-pressure change and flow control 121, 123, 124, 127, control area 128, 130, 132, 133, 134, 136, 139, 141, 142-Pipeline

[0032] 104- buffer zone 105- a burnt zone 106, 108, 110, 112- catalytic

[0033] Chemical feed leg

[0034] 107-Second stage charring area 109-Drying area 111-Oxychlorination area

[0035] 113-Cooling area 114-Gas isolation area 115-Lifter 118, 125, 137, 140-119, 126-heat exchanger 122, 129, 131, 135-electric Press Heater

[0036] 138-Cooler 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] One aspect of the present invention provides a method for regenerating a dehydrogenation catalyst, wherein the method comprises:

[0039] (1) The catalyst to be used is subjected to a first coking process in the first coking zone and then subjected to a second coking process in the second coking zone;

[0040] (2) passing the second charred product through a drying zone, an oxychlorination zone, and a cooling zone to obtain a regenerated catalyst;

[0041] The gases exhausted from the first-stage charring zone, the second-stage charring zone and the oxychlorination zone are circulated independently.

[0042] In the present invention, the drying zone is placed below the charring zone to achieve independent circulation of the gases in the charring zone and the oxychlorination zone, and the oxygen content and charring conditions of the two charring zones are controlled separately, so as to effectively remove carbon deposits of different degrees of carbonization on the catalyst to be regenerated; the oxychlorination zone achieves self-circulation, and by maintaining appropriate oxygen content and chlorine content in the oxychlorination zone, the dispersion of precious metals in the low-carbon alkane dehydrogenation catalyst can be increased, thereby improving the regeneration effect of the catalyst.

[0043] In the present invention, unless otherwise stated, "the gases exhausted from the first charring zone and the second charring zone are circulated independently of each other" means that a portion of the gas exhausted from the first charring zone is circulated back to the first charring zone as the first circulating gas, without going to the second charring zone; a portion of the gas exhausted from the second charring zone is circulated back to the second charring zone as the second circulating gas, without going to the first charring zone, that is, the regenerated gases from the first charring zone and the second charring zone will not cross-circulate.

[0044] In the present invention, unless otherwise stated, the regeneration gas in the charring zone refers to the gas introduced into the charring zone, which is the gas drawn out from the charring zone and then mixed with the air and / or the gas exhausted from the drying zone and then circulated back into the charring zone. When the regeneration system is started for the first time, gas can be introduced from outside the system as the regeneration gas for the charring zone.

[0045] In the present invention, "the gas from the oxychlorination zone is circulated independently" means that the gas discharged from the oxychlorination zone is circulated back to the oxychlorination zone.

[0046] According to the present invention, preferably, the gas exhausted from the drying zone is divided into gas I and gas II.

[0047] According to the present invention, preferably, the gas I is mixed with the first circulating gas discharged from the first charring zone and circulated back to the first charring zone. In the present invention, the regeneration gas of the first charring zone is introduced from outside the system or is the gas I mixed with the first circulating gas and then circulated back to the first charring zone.

[0048] In the present invention, the first circulating gas is a part of the gas discharged from the first charring zone. The flow rate of the first circulating gas is determined by the regeneration scale of the device. Those skilled in the art can adjust the mixing of gas I so that the oxygen content in the regeneration gas of the first charring zone meets the conditions of the first charring. In the present invention, the regeneration scale of the device refers to the catalyst circulation quality.

[0049] According to the present invention, preferably, the gas II is mixed with the second circulating gas discharged from the second stage charring zone and circulated back to the second stage charring zone. In the present invention, the regeneration gas of the second stage charring zone is the gas that is mixed with the second circulating gas and circulated back to the second stage charring zone.

[0050] In the present invention, the second circulating gas is a part of the gas discharged from the second stage charring zone. The flow rate of the second circulating gas is determined by the regeneration scale of the device. Those skilled in the art can adjust the mixing of gas II so that the oxygen content in the regeneration gas of the second stage charring zone meets the second charring conditions.

[0051] In the present invention, preferably, the above cycle can flexibly control the conditions of the first charring and the second charring to improve the regeneration capacity of the regenerator.

[0052] In the present invention, the flow rates of gas I and gas II are determined by the regeneration scale of the device. According to the different flow rates of regeneration gas required for the first and second charring zones of the device, technicians in this field can make adaptive adjustments to meet the conditions of the first and second charring.

[0053] According to the present invention, preferably, the oxygen content in the regeneration gas in the first coking zone is 0.2-1% by volume, preferably 0.5-1% by volume.

[0054] According to the present invention, preferably, the first charring conditions include: the inlet temperature of the regeneration gas is 350-600°C, preferably 400-500°C; the pressure is 0.1-1MPa, preferably 0.3-0.8MPa; the gas-to-gas volume ratio is 2000-20000:1, preferably 5000-10000:1; the residence time is 10-600min, preferably 30-480min.

[0055] In the present invention, unless otherwise specified, the pressure is gauge pressure.

[0056] In the present invention, preferably, the oxygen content in the regeneration gas of the first coking zone is low, so that carbon deposits with a low degree of carbonization can be removed during the first coking process, thereby reducing the carbon content of the obtained regenerated catalyst.

[0057] According to the present invention, preferably, the oxygen content in the regeneration gas in the second-stage coking zone is 1-10% by volume, preferably 2-6% by volume.

[0058] According to the present invention, preferably, the conditions for the second charring include: the inlet temperature of the regeneration gas is 400-600°C, preferably 440-550°C; the pressure is 0.1-1MPa, preferably 0.4-0.8MPa; the gas-to-agent volume ratio is 2000-20000:1, preferably 5000-10000:1; the residence time is 10-600min, preferably 30-480min.

[0059] In the present invention, the oxygen content in the regeneration gas of the second-stage coking zone is higher than that in the first-stage coking zone. Increasing the oxygen content in the regeneration gas can burn away carbon deposits that are difficult to burn.

[0060] In the present invention, there are carbon deposits with low carbonization degree that are easy to burn and carbon deposits with high carbonization degree that are difficult to burn on the regenerated catalyst. Different burning conditions and oxygen content of regeneration gas are controlled in the two-step burning process to remove carbon deposits with different carbonization degrees in a targeted manner. In the burning process, it is avoided that the oxygen content is too low, resulting in incomplete burning of the regenerated catalyst and the presence of unburned cores in the catalyst core; and that the oxygen content is too high, resulting in runaway temperature damage to the catalyst and the internal components of the regenerator.

[0061] According to the present invention, preferably, the drying conditions of the drying zone include: the gas temperature at the inlet of the drying zone is 120-600°C, preferably 400-600°C; the oxygen content in the drying gas is 0.1-21% by volume, preferably 5-21% by volume; the gas-agent volume ratio is 100-500:1, preferably 200-400:1; the residence time is 20-100min, preferably 30-80min.

[0062] In the present invention, preferably, the dew point of the gas at the inlet of the drying zone is lower than -60°C, and the water content of the gas at the outlet of the drying zone is not particularly limited.

[0063] The two charring zones of the regeneration method of the present invention are completely isolated, and the gases therein circulate separately, and the oxygen content and regeneration pressure are controlled separately, which can improve the regeneration capacity and charring flexibility, and can flexibly adjust the conditions of the first charring zone and the second charring zone according to the catalyst regeneration situation. The drying zone is located below the second charring zone, and the moisture generated during the charring process is first removed, so that the dried catalyst to be regenerated enters the oxychlorination zone, reducing the side reaction between the chlorinating agent and water. The gas in the oxychlorination zone circulates separately, and the catalyst flows through the set material legs. The oxygen concentration in the oxychlorination zone is not limited by the charring zone, and a higher oxygen content and chlorine content can be maintained, and the loss of chlorine is reduced, and the injection amount of the chlorinating agent is reduced, so that the oxychlorination effect of the catalyst to be regenerated is better.

[0064] According to the present invention, preferably, the oxychlorination conditions in the oxychlorination zone include: the gas temperature at the inlet of the oxychlorination zone is 120-600°C, preferably 400-550°C; the oxygen content is 3-21% by volume, preferably 7-21% by volume; the gas volume ratio is 100-500:1, preferably 200-400:1; the residence time is 10-100min, preferably 30-50min.

[0065] According to the present invention, preferably, a chlorinating agent is also introduced into the oxychlorination zone, and the chlorinating agent is chlorine gas and / or an organic chloride. In the present invention, the injection amount of the chlorinating agent is not particularly limited, so that the chlorine content in the oxychlorination zone meets the oxychlorination conditions. The chlorine content in the oxychlorination zone is 0.02-1% by mass, preferably 0.1-0.5% by mass, based on the catalyst circulation mass.

[0066] In the present invention, the organic chloride is a conventional organic chloride used for catalyst regeneration in the art, and is preferably selected from at least one of tetrachloroethylene, dichloroethane and trichloroethane.

[0067] In the present invention, preferably, air and / or oxygen are optionally introduced into the oxychlorination zone together with the chlorinating agent.

[0068] In the present invention, preferably, the first circulating gas is supplemented with the gas containing the chlorinating agent, mixed with the gas I, and circulated back to the first stage charring zone; the second circulating gas is supplemented with the gas containing the chlorinating agent, mixed with the gas I, and circulated back to the second stage charring zone. Adding chlorine to the first and second stage charring zones can reduce the metal aggregation of the catalyst during the charring process.

[0069] In the present invention, the amount of the gas containing the chlorinating agent supplemented to the first circulating gas and the second circulating gas is not particularly limited. Preferably, based on the catalyst circulation mass, the mass of Cl element in the first charring zone is 0.01-0.5 mass %, and the mass of Cl element in the second charring zone is 0.01-0.5 mass %.

[0070] According to the present invention, preferably, the chlorine content in the oxychlorination zone is 0.02-1% by mass, preferably 0.1-0.5% by mass, based on the catalyst circulation mass. The role of chlorine is to provide acidity and disperse metals for the catalyst, and it is an indispensable component of the bifunctional catalyst. Too much or too little chlorine will affect the catalyst performance.

[0071] According to the present invention, preferably, the chlorinating agent is mixed with the third circulating gas discharged from the oxychlorination zone and then circulated back to the oxychlorination zone. According to conventional schemes, the chlorine in the oxychlorination zone is often discharged through tail gas or supplemented to the charring zone, and discharged after charring, which will inevitably cause waste of chlorine and increase processing and investment costs. The present invention reduces chlorine loss through self-circulation of the oxychlorination zone without external chlorine discharge, and ensures the chlorine content in the oxychlorination zone by reasonably adjusting the chlorine injection amount.

[0072] According to the present invention, preferably, the cooling conditions of the cooling zone include: the oxygen content in the cooling gas is 0.1-21% by volume, preferably 5-21% by volume; the gas temperature at the inlet of the cooling zone is 0-200°C, preferably 20-80°C; the gas-agent volume ratio is 100-500:1, preferably 200-400:1; the residence time is 20-100min, preferably 30-80min.

[0073] In the present invention, the catalyst is cooled to 100°C-400°C, preferably 100°C-200°C. In the present invention, the catalyst is lifted and then enters the reducer, and is reduced to obtain a regenerated catalyst. The regenerated catalyst enters the moving bed reaction zone to participate in the dehydrogenation reaction, and the catalyst to be regenerated obtained by the dehydrogenation reaction enters the catalyst regenerator after lifting, dust removal and metering to regenerate the catalyst to complete the cycle.

[0074] According to the present invention, preferably, the inlet pressure of the first-stage charring zone is 1-20 kPa higher than the inlet pressure of the second-stage charring zone, preferably 1-10 kPa higher.

[0075] According to the present invention, preferably, the inlet pressure of the second-stage charring zone is 1-20 kPa higher than the outlet pressure of the drying zone, preferably 2-10 kPa higher.

[0076] According to the present invention, preferably, the outlet pressure of the oxychlorination zone is 1-20 kPa higher than the pressure of the drying zone, preferably 2-10 kPa higher.

[0077] According to the present invention, preferably, the outlet pressure of the cooling zone is 0-20 kPa higher than the pressure of the oxychlorination zone, preferably 2-10 kPa higher.

[0078] In the present invention, the pressure difference between each zone is limited to ensure the safety of the regenerator and prevent the gas with high oxygen content from flowing into the area with low oxygen content, causing temperature runaway and affecting the normal circulation of the gas circuit.

[0079] In the present invention, the device used for regenerating the spent catalyst is not particularly limited, as long as it meets the conditions specified in the regeneration method of the present invention.

[0080] 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.

[0081] The spent catalyst of the present invention can be a spent catalyst in different catalytic fields, preferably a spent catalyst obtained by dehydrogenation of light alkanes. The source of the spent catalyst is not particularly limited, and can be purchased commercially or prepared by existing methods.

[0082] According to the present invention, preferably, the spent catalyst comprises a carrier and an active component.

[0083] In the present invention, preferably, the spent catalyst further comprises carbon, and the carbon content is 1-5% by mass, preferably 1-3% by mass, based on the total weight of the carrier and the active component.

[0084] According to the present invention, preferably, the support is an alumina support, preferably θ-alumina.

[0085] According to the present invention, preferably, the active component comprises platinum group metal elements, IVA group metal elements, alkali metal elements and chlorine elements.

[0086] In the present invention, preferably, the platinum group metal element is platinum and / or palladium, preferably platinum.

[0087] In the present invention, preferably, the IVA group metal is selected from at least one of silicon, germanium and tin, preferably tin.

[0088] In the present invention, preferably, the alkali metal is selected from at least one of potassium, sodium and rubidium, preferably potassium.

[0089] In the present invention, preferably, based on the total mass of the carrier, the content of the platinum group metal element is 0.1-1 mass %; the content of the IVA group metal element is 0.1-1 mass %; the content of the alkali metal element is 0.5-2 mass %; and the content of the chlorine element is 0.4-2 mass %.

[0090] In the present invention, preferably, the platinum group metal element is platinum, and the content of the platinum group metal element is 0.1-1% by mass based on the total amount of the carrier.

[0091] In the present invention, preferably, the IVA group metal element is tin, and the content of the IVA group metal element is 0.1-1% by mass based on the total amount of the carrier.

[0092] In the present invention, preferably, the alkali metal element is potassium, and the content of the alkali metal element is 0.5-2% by mass based on the total amount of the carrier.

[0093] In the present invention, preferably, the chlorine content is 0.5-1.5% by mass based on the total amount of the carrier.

[0094] In the present invention, preferably, the carbon content in the regenerated catalyst is less than 0.02 mass %, preferably less than 0.01 mass %.

[0095] 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.

[0096] The following combination Figure 1 Further illustrating the regeneration method of the present invention, the regeneration process flow of the catalyst to be regenerated is as follows Figure 1As shown, the regeneration cycle process of the catalyst to be regenerated is as follows: the catalyst to be regenerated flows out from the bottom of the moving bed reaction zone, passes through a lifter (not shown in the figure), and enters the catalyst separation hopper 102 via pipeline 101 to separate the dust in the catalyst. The catalyst to be regenerated after elutriation enters the pressure conversion and flow control zone 103. Under the action of gravity, the catalyst to be regenerated enters the first stage charring zone 105 via the buffer zone 104 for the first charring, enters the second stage charring zone 107 via the catalyst unloading leg 106 for the second charring, enters the drying zone 109 via the catalyst unloading leg 108 for drying, enters the oxychlorination zone 111 via the catalyst unloading leg 110 for oxychlorination, enters the cooling zone 113 via the catalyst unloading leg 112 for cooling, and then enters the gas isolation zone 114. In the gas isolation zone 114, the oxygen environment is converted into a hydrogen environment, and then lifted to a reduction tank (not marked in the figure) through the lifter 115 and the lifting pipeline. In the reduction tank, the oxidized catalyst is reduced to a reduced catalyst, and the reduced catalyst enters the moving bed reaction zone to participate in the reaction and complete the catalyst cycle.

[0097] According to a preferred embodiment of the present invention, Figure 1 As shown, the gas circulation process is as follows: the first stage charring area 105 is introduced into the regeneration gas for the first charring, and the generated gas is discharged through the pipeline 116, a small amount is discharged to the atmosphere through the pipeline 117, most of it is pressurized by the booster 118 as the first circulation gas, and the heat exchanger 119 is mixed with the drying area gas I introduced from the pipeline 120, and then it is heated by the electric heater 122 through the pipeline 121 and circulated back to the first stage charring area 105, so as to realize independent circulation. The regeneration gas of the second stage charring area 107 is subjected to the second charring, and the generated gas is discharged through the pipeline 123, a small amount is discharged to the atmosphere through the pipeline 124, and most of it is pressurized by the booster 125 as the second circulation gas, and the heat exchanger 126 is mixed with the drying area gas II introduced from the pipeline 127, and then it is heated by the electric heater 129 through the pipeline 128 and circulated back to the second stage charring area 107, so as to realize independent circulation.

[0098] Air is introduced through pipeline 130, part of which is heated by electric heater 131 and enters drying zone 109. The dry gas flows upward to remove moisture from the catalyst. The dried gas is discharged from pipeline 132, part of which is used as gas I of the first stage charring zone 105 and gas II of the second stage charring zone 107, and the excess is discharged through pipeline 133. The chlorinating agent is introduced through pipeline 134, mixed with the air from pipeline 130 and heated by electric heater 135 to enter oxychlorination zone 111. The gas in oxychlorination zone flows upward through the catalyst to be regenerated, and oxychlorination is performed in oxychlorination zone 111, so that the metal Pt accumulated on the catalyst to be regenerated is redispersed. The oxychlorinated gas is drawn out from pipeline 136, pressurized by booster 137, mixed with supplementary air introduced from pipeline 130 and chlorinating agent introduced from pipeline 134, and circulated back to oxychlorination zone 111 to achieve independent circulation.

[0099] Part of the air introduced from pipeline 130 is cooled by cooler 138 and then enters cooling zone 113 to cool the catalyst to be regenerated. The cooling air discharged from cooling zone 113 is led out from pipeline 139, pressurized by supercharger 140, mixed with the air introduced from pipeline 130, and circulated back to cooling zone 113 to complete the cycle. Chloride is introduced into the first and second charring zones 105 and 107 respectively through pipelines 141 and 142.

[0100] In the present invention, the regenerated catalyst is used for the dehydrogenation reaction of light alkanes, wherein the light alkanes are C2-C4 alkanes. The source of the light alkanes is not particularly limited, and is preferably at least one of refinery byproducts, shale gas and oilfield associated gas.

[0101] In the present invention, the dehydrogenation reaction conditions are not particularly limited and can be conventional low-carbon dehydrogenation reactions in the art. According to a preferred embodiment of the present invention, the dehydrogenation reaction conditions 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 molar ratio of 0.2-2:1, preferably 0.4-0.7:1; a feed volume space velocity of 0.1-10h -1 , preferably 0.3-8h -1 .

[0102] The present invention will be described in detail below through examples and comparative examples. In the following examples and comparative examples,

[0103] The metal Pt dispersion in the catalyst was measured by a Micromeritics AutoChem 2920 chemical adsorption instrument;

[0104] The carbon content in the catalyst was analyzed by the Q / SH 3360 317—2020 standard method;

[0105] During the regeneration process, the oxygen content was measured by an online oxygen analyzer, and the chloride content was measured by ion chromatography;

[0106] The dehydrogenation catalyst was industrial grade PST-100, purchased from Hunan Jianchang Petrochemical Co., Ltd.;

[0107] The chlorinating agent is chlorine gas.

[0108] Dehydrogenation of light alkanes to obtain spent catalysts

[0109] In the moving bed reaction zone of the microreactor, 2 ml of industrial grade PST-100 dehydrogenation catalyst was loaded, and a mixture of hydrogen and propane was used as the raw material. The reaction was carried out at 620°C, 0.11 MPa, and a propane feed volume space velocity of 2.8 h -1The reaction was carried out for 10 hours under the conditions of a hydrogen / propane molar ratio of 0.5:1 to obtain a spent catalyst. The carbon content of the spent catalyst was analyzed by Q / SH 3360 317-2020 standard method and was found to be 1.5% by mass.

[0110] Example 1

[0111] The spent catalyst obtained by dehydrogenation of light alkanes is Figure 1 The process shown carries out the circulation of the spent catalyst and the circulation of the regenerated gas.

[0112] The regenerated catalyst flows out from the bottom of the moving bed reaction zone, passes through a lifter (not shown), and enters a catalyst separation hopper 102 via pipeline 101 to separate dust from the catalyst. The regenerated catalyst after elutriation enters a pressure conversion and flow control zone 103. Under the action of gravity, the regenerated catalyst enters a first charring zone 105 via a buffer zone 104 for the first charring. The conditions for the first charring are: the inlet temperature of the regenerated gas is 460°C, the oxygen content in the regenerated gas is 0.9% by volume, the pressure is 0.4MPa, the residence time is 50min, and the gas-to-agent volume ratio is 8000:1.

[0113] The catalyst to be regenerated after the first charring enters the second charring zone 107 through the catalyst feed leg 106 for the second charring. The conditions for the second charring are: the inlet temperature of the regeneration gas is 480°C, the oxygen content in the regeneration gas is 2.5% by volume, the pressure is 0.4 MPa, the residence time is 50 minutes, and the gas-to-agent volume ratio is 8000:1.

[0114] The second charred catalyst enters the drying zone 109 through the catalyst feed leg 108 for drying. The drying conditions are: inlet temperature is 550°C, oxygen content in the drying gas is 21% by volume, gas-to-agent volume ratio is 200:1, and residence time is 40 minutes.

[0115] The catalyst to be regenerated enters the oxychlorination zone 111 through the catalyst feed leg 110 for oxychlorination. The conditions for oxychlorination are: the inlet temperature is 490°C, the oxygen content in the oxychlorination zone is 21% by volume. The gas-to-agent volume ratio is 200:1; the residence time is 40 min. Based on the mass of the catalyst to be regenerated, the chlorine content in the oxychlorination zone is 0.4% by mass, and the chlorinating agent injection amount is 2.7 g / h. The catalyst to be regenerated after oxychlorination enters the cooling zone 113 through the catalyst feed leg 112 for cooling. The cooling conditions are: the oxygen content in the cooling gas is 21% by volume, the inlet gas temperature is 50°C, the gas-to-agent volume ratio is 100-500:1, preferably 200-400:1; the residence time is 20-100 min, preferably 30-80 min. The catalyst temperature after cooling is 200°C.

[0116] Subsequently, the catalyst to be regenerated enters the gas isolation zone 114, where the oxygen environment is converted into a hydrogen environment, and then is lifted to a reduction tank (not marked in the figure) through the lift 115 and the lifting pipeline. In the reduction tank, the oxidized catalyst is reduced to a reduced catalyst to obtain a regenerated catalyst. The reduced catalyst enters the moving bed reaction zone to participate in the reaction, thereby completing the catalyst cycle.

[0117] The gas circulation process is as follows: the regenerated gas of the first stage charring area 105 undergoes the first charring, and the generated gas is discharged through pipeline 116, a small amount of which is discharged to the atmosphere through pipeline 117, and most of it is pressurized by the booster 118 as the first circulation gas, and then mixed with the drying area gas I introduced from pipeline 120 after heat exchange by the heat exchanger 119, and then circulated back to the first stage charring area 105 after heating by the electric heater 122 through pipeline 121, thus realizing independent circulation. The regenerated gas of the second stage charring area 107 undergoes the second charring, and the generated gas is discharged through pipeline 123, a small amount of which is discharged to the atmosphere through pipeline 124, and most of it is pressurized by the booster 125 as the second circulation gas, and then mixed with the drying area gas II introduced from pipeline 127 after heat exchange by the heat exchanger 126, and then circulated back to the second stage charring area 107 after heating by the electric heater 129 through pipeline 128, thus realizing independent circulation.

[0118] Air is introduced through pipeline 130, and part of the air is heated by electric heater 131 and enters drying zone 109. The dry gas flows upward to remove moisture from the catalyst. The dried gas is discharged from pipeline 132, part of which is used as supplementary gas for the first stage charring zone 105 and the second stage charring zone 107, and the excess is discharged through pipeline 133. The chlorinating agent is introduced through pipeline 134, mixed with the air from pipeline 130, and heated by electric heater 135 before entering oxychlorination zone 111. The gas in oxychlorination zone flows upward through the catalyst to be regenerated, and oxychlorination is performed in oxychlorination zone 111, so that the metal Pt accumulated on the catalyst to be regenerated is redispersed. The oxychlorinated gas is drawn out from pipeline 136, pressurized by booster 137, mixed with supplementary air introduced from pipeline 130 and chlorinating agent introduced from pipeline 134, and circulated back to oxychlorination zone 111 to achieve independent circulation.

[0119] Part of the air introduced from pipeline 130 is cooled by cooler 138 and then enters cooling zone 113 to cool the catalyst to be regenerated. The cooling air discharged from cooling zone 113 is led out from pipeline 139, pressurized by supercharger 140, mixed with the air introduced from pipeline 130, and circulated back to cooling zone 113 to complete the cycle. Chloride is introduced into the first and second charring zones 105 and 107 respectively through pipelines 141 and 142.

[0120] Example 2

[0121] The catalyst to be regenerated is regenerated according to the method of Example 1, except that the oxygen content in the regeneration gas of the first charring zone is 0.9% by volume, and the oxygen content in the regeneration gas of the second charring zone is 0.9% by volume. Other conditions are the same as in Example 1.

[0122] Example 3

[0123] The regeneration of the spent catalyst is carried out according to the method of Example 1, except that the chlorine content in the oxychlorination zone is 0.08% by mass based on the mass of the spent catalyst. Other conditions are the same as in Example 1.

[0124] Comparative Example 1

[0125] The regeneration of the spent catalyst is carried out according to the method of Example 1. The spent catalyst is the same as that of Example 1, which is a spent catalyst obtained by dehydrogenation of low-carbon alkanes. The difference is that

[0126] The first charring conditions are as follows: the inlet temperature of the regeneration gas is 460°C, the oxygen content in the regeneration gas is 0.9% by volume, the pressure is 0.4 MPa, the average residence time is 50 minutes, and the gas-to-agent volume ratio is 8000:1.

[0127] The conditions for the second coking are: the inlet temperature of the regeneration gas is 480°C, the oxygen content in the regeneration gas is 2.5% by volume, the pressure is 0.4 MPa, the average residence time is 50 minutes, and the gas-to-agent volume ratio is 8000:1.

[0128] No drying zone is set up, and cooling zone I is set up after the second stage charring zone. The cooling conditions of cooling zone I are: the cooling gas inlet temperature is 450°C, the oxygen content in the cooling gas is 2.5% by volume, the pressure is 0.4MPa, and the catalyst temperature after cooling is 430°C.

[0129] After cooling, the catalyst to be regenerated enters the oxychlorination zone for oxychlorination, and the conditions are the same as those in Example 1. After oxychlorination, the catalyst to be regenerated enters the cooling zone II for cooling. The exhaust gas in the oxychlorination zone is not circulated, and after being discharged, the chloride is removed by the dechlorination tank and then discharged into the atmosphere. The cooling conditions are: the oxygen content in the cooling gas is 21% by volume, the inlet gas temperature is 50°C, and the catalyst temperature after cooling is 200°C.

[0130] Test Case

[0131] The regeneration results of the spent catalysts of the examples of the present invention and the comparative examples are shown in Table 1. The color of the catalyst was obtained by direct observation.

[0132] The Pt dispersion of the catalyst refers to the ratio of the number of Pt atoms on the catalyst surface to the total number of Pt atoms on the catalyst.

[0133] Table 1

[0134]

[0135] Note: The gray agent ratio refers to the proportion of gray agent in the obtained regenerated catalyst to the total amount of catalyst.

[0136] It can be seen from the results in Table 1 that the method provided by the present invention can improve the dispersion of precious metals in the light alkane dehydrogenation catalyst and improve the regeneration effect of the catalyst.

[0137] 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 a dehydrogenation catalyst, characterized in that: The method includes: (1) The catalyst to be used is subjected to a first coking process in the first coking zone and then subjected to a second coking process in the second coking zone; (2) passing the second charred product through a drying zone, an oxychlorination zone, and a cooling zone to obtain a regenerated catalyst; The gases exhausted from the first-stage charring zone, the second-stage charring zone and the oxychlorination zone are circulated independently.

2. The method according to claim 1, wherein: The gas discharged from the drying zone is divided into gas I and gas II. Gas I is mixed with the first circulating gas discharged from the first charring zone and circulated back to the first charring zone. Gas II is mixed with the second circulating gas discharged from the second charring zone and circulated back to the second charring zone.

3. The method according to claim 1 or 2, wherein: The oxygen content of the regeneration gas in the first coking zone is 0.2-1% by volume, preferably 0.5-1% by volume; Preferably, the oxygen content in the regeneration gas in the second-stage coking zone is 1-10% by volume, preferably 2-6% by volume.

4. The method according to any one of claims 1 to 3, wherein: The first charring conditions include: the inlet temperature of the regeneration gas is 350-600°C, preferably 400-500°C; the pressure is 0.1-1MPa, preferably 0.3-0.8MPa; the gas-to-agent volume ratio is 2000-20000:1, preferably 500010000:1; the residence time is 10-600min, preferably 30-480min.

5. The method according to any one of claims 1 to 4, wherein: The second charring conditions include: the inlet temperature of the regeneration gas is 400-600°C, preferably 440-550°C; the pressure is 0.1-1MPa, preferably 0.4-0.8MPa; the gas-agent volume ratio is 2000-20000:1, preferably 5000-10000:1; the residence time is 10-600min, preferably 30-480min.

6. The method according to any one of claims 1 to 5, wherein: The drying conditions of the drying zone include: the gas temperature at the inlet of the drying zone is 120-600° C., preferably 400-600° C.; the oxygen content in the drying gas is 0.1-21% by volume, preferably 5-21% by volume.

7. The method according to any one of claims 1 to 6, wherein: The oxychlorination conditions of the oxychlorination zone include: the gas temperature at the inlet of the oxychlorination zone is 120-600°C, preferably 400-550°C; the oxygen content is 3-21% by volume, preferably 7-21% by volume; Preferably, a chlorinating agent is also introduced into the oxychlorination zone, and the chlorinating agent is chlorine gas and / or an organic chloride; Preferably, the chlorine content in the oxychlorination zone is 0.02-1% by mass, preferably 0.1-0.5% by mass, based on the mass of the catalyst circulation; Preferably, the chlorinating agent is mixed with the third circulating gas discharged from the oxychlorination zone and then circulated back to the oxychlorination zone.

8. The method according to any one of claims 1 to 7, wherein: The cooling conditions of the cooling zone include: the oxygen content in the cooling gas is 0.1-21% by volume, preferably 5-21% by volume; the gas temperature at the inlet of the cooling zone is 0-200°C, preferably 20-80°C.

9. The method according to any one of claims 1 to 8, wherein: The inlet pressure of the first stage charring zone is 1-20 kPa higher than the inlet pressure of the second stage charring zone, preferably 1-10 kPa higher; Preferably, the inlet pressure of the second-stage charring zone is 1-20 kPa higher than the outlet pressure of the drying zone, preferably 2-10 kPa higher; Preferably, the outlet pressure of the oxychlorination zone is 1-20 kPa higher than the inlet pressure of the drying zone, preferably 2-10 kPa higher; Preferably, the outlet pressure of the cooling zone is 0-20 kPa higher than the inlet pressure of the oxychlorination zone, preferably 2-10 kPa higher.

10. The method according to any one of claims 1 to 9, wherein: The catalyst to be produced comprises a carrier and an active component; Preferably, the support is an alumina support, preferably θ-alumina; Preferably, the active component comprises platinum group metal elements, IVA group metal elements, alkali metal elements and chlorine elements.

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