A desiccant taking into account desulfurization performance, its preparation method and application

Abstract

The present disclosure relates to a desiccant that takes into account desulfurization performance, its preparation method and application. The desiccant includes a carrier and an active metal component supported on the carrier; the carrier contains 13X molecular sieve, and the active metal component includes zinc oxide. The desiccant provided by the present disclosure can combine the two processes of desulfurization and drying into one, and has good regeneration performance.

Description

Technical Field

[0001] The present disclosure relates to the field of desiccants, and in particular, to a desiccant that takes into account desulfurization performance, a preparation method thereof, and an application thereof. Background Art

[0002] With the increasingly strict environmental protection requirements, the emission standards for vehicle gasoline products have been rapidly upgraded. The vehicle gasoline standard has more stringent restrictions on the contents of aromatics, olefins, and benzene. At the same time, the control index of the gasoline distillation range T50 has been reduced. The restrictions on these high-octane components such as aromatics and olefins will lead to a decrease in the octane number of the gasoline used. The compensatory measure is usually to increase the isoparaffins in the gasoline components, which means that more high-octane high-quality light gasoline blending components such as C5 / C6 isomerized gasoline and alkylated oil can be added to the vehicle gasoline.

[0003] Alkane isomerization is one of the important processes for developing clean fuels. The catalysts used therein are mainly divided into three types: molecular sieve catalysts, solid superacid catalysts, and chlorine-containing alumina catalysts. The above catalysts can all be loaded with noble metal components. The isomerization process using a molecular sieve catalyst has a simple process and relatively wide requirements for the impurity content of the feedstock oil. At present, it has been widely used in industry. However, such catalysts have a high reaction temperature (above 250°C) and low isomerization activity. The octane number RON of the isomerization product in a single pass is about 80. Since the solid superacid catalyst has a certain acidity and high isomerization activity, the isomerization reaction can be carried out at a lower temperature (above 140°C) to obtain a higher isomerization rate. However, in the reaction process of such catalysts, SO4 2- is easily lost and cannot be directly replenished, and it requires shutdown for regeneration and sulfur supplementation.

[0004] The chlorine-containing alumina catalyst is the catalyst with the highest isomerization activity in alkane isomerization. Since the alkane isomerization reaction is a slightly exothermic reaction thermodynamically, about 6-8 kJ / mol, low temperature is more favorable for the isomerization reaction. Compared with the medium-temperature molecular sieve-type isomerization catalyst, under the same single-pass operating conditions, the product octane number of the low-temperature catalyst is about 4-5 units higher. In addition, due to the low reaction temperature of the chlorinated alumina catalyst, cracking is extremely rare, the liquid yield is high, and the operating cost and operating energy consumption are low. It is the development direction of C5 / C6 isomerization catalysts and technologies.

[0005] Although the C5 / C6 low-temperature isomerization technology has relatively high low-temperature isomerization performance, the low-temperature isomerization catalyst has strict limiting conditions for the control of impurities in the feedstock. Wu Zhenhua mentioned in the article "Summary of Production and Operation of C5 / C6 Low-temperature Isomerization Unit" in "Petroleum Refining and Chemical Industry", Vol. 50, No. 1 that impurities such as water, nitrogen, and oxygen in the feedstock will cause the isomerization catalyst to be permanently deactivated. Therefore, it is necessary to refine the impurities in the isomerization feedstock to ensure that the contents of impurities such as water, oxygen, nitrogen, and sulfur in the feedstock are all lower than 0.1 μg / g. To meet the above requirements, the isomerization feedstock oil needs to undergo multiple refining processes such as normal-temperature desulfurization, denitrification, high-temperature desulfurization, and dehydration, and the make-up hydrogen used in the isomerization reaction needs to undergo multiple processes such as desulfurization, dechlorination, methanation, and dehydration. In the actual application process, the service life of various refining agents in the refining unit is only about 1 year, and the replacement is frequent. Therefore, for the C5 / C6 low-temperature isomerization technology, simplifying the refining technology of the feedstock has practical significance.

[0006] Chinese patent document CN102513059A discloses a method for preparing binderless 13X molecular sieve. The 13X molecular sieve raw powder is mixed with kaolin-like and attapulgite-like clays, granulated, screened, calcined, and then immersed in sodium silicate to obtain a novel binderless 13X molecular sieve product. The binderless 13X molecular sieve of this invention has better effective adsorption capacity, adsorption rate, desorption rate, and mechanical strength than ordinary 13X molecular sieve, and is used in pressure swing adsorption for hydrogen production, oxygen production, adsorption separation, etc. Chinese patent document CN103041771A discloses a gasoline deep desulfurization adsorbent and its preparation method. Using 13X molecular sieve as the carrier, silver ions are loaded onto the carrier by ion exchange method, and the molecular sieve desulfurization adsorbent loaded with silver ions is obtained after calcination and activation. This adsorbent has a long service life and can be regenerated. This adsorbent has a high adsorption capacity and adsorption selectivity for thiophene and its derivatives and benzothiophene in gasoline. However, the prior arts have not combined the two processes of drying and desulfurization. Summary of the Invention

[0007] The purpose of the present disclosure is to provide a method for desulfurization and dehydration of C5 / C6 isomerization feedstock oil.

[0008] To achieve the above purpose, the first aspect of the present disclosure provides a desiccant that takes into account desulfurization performance. The desiccant includes a carrier and an active metal component loaded on the carrier; the carrier contains 13X molecular sieve, and the active metal component includes zinc oxide.

[0009] Optionally, based on the total weight of the desiccant, the content of 13X molecular sieve in the desiccant is 99.8 - 80.0% by weight, preferably 99.5 - 95% by weight; the content of zinc oxide is 0.2 - 20% by weight, preferably 0.5 - 5% by weight.

[0010] Optionally, the preparation method of the desiccant taking into account desulfurization performance includes:

[0011] Immerse spherical 13X molecular sieve in Zn(NO3)2 solution to obtain the impregnated material; perform the first drying treatment and the first calcination treatment on the impregnated material; or,

[0012] Mix powdered 13X molecular sieve with ZnO, add a binder and form into balls or extrude into strips to obtain the formed material, and perform the second drying treatment and the second calcination treatment on the formed material; or,

[0013] Mix sodium hydroxide and water evenly, then add sodium silicate and sodium aluminate in sequence and stir to obtain the first mixed material; perform aging treatment on the first mixed material, and then perform crystallization treatment with Zn(NO3)2 to obtain the second material; filter and wash the second material and then perform the third drying treatment.

[0014] Optionally, the conditions of the impregnation treatment include: temperature is 50 - 70 °C, time is 3 - 6 h; the conditions of the first drying treatment include: temperature is 110 - 130 °C, time is 3 - 6 h; the conditions of the first calcination treatment include: temperature is 530 - 560 °C, time is 3 - 6 h.

[0015] Optionally, the conditions of the second drying treatment include: temperature is 110 - 130 °C, time is 3 - 6 h; the conditions of the second calcination treatment include: temperature is 530 - 550 °C, time is 3 - 6 h.

[0016] Optionally, the molar ratio of SiO2:Na2O:Al2O3:H2O in the first mixed material after mixing is 2.5 - 3.4:2.8 - 3.5:1:100 - 300; the mass ratio of the first material after aging treatment to Zn(NO3)2 after mixing is 90 - 94:6 - 10; the conditions of the aging treatment include stirring treatment, and the time of the stirring treatment is 20 - 30 h; the conditions of the crystallization treatment include: temperature is 90 - 100 °C, time is 12 - 24 h; the conditions of the third drying treatment include: temperature is 110 - 120 °C, time is 10 - 12 h.

[0017] The second aspect of the present disclosure provides a method for desulfurization and dehydration of C5 / C6 isomerization feedstock, the method includes: contacting the C5 / C6 isomerization feedstock with a desiccant in a reactor to obtain the desulfurized and dehydrated C5 / C6 isomerization feedstock and the spent desiccant.

[0018] Optionally, the hydrogen sulfide content in the C5 / C6 isomerization feedstock oil is not higher than 0.5 μg / g, the water content is not higher than 10 μg / g, the nitrogen content is not higher than 0.1 μg / g, the chlorine content is not higher than 0.5 μg / g, and the content of benzene and components above C7 is not higher than 3%; the C5 / C6 isomerization feedstock oil is selected from at least one of the top naphtha of the distillation tower, the top light naphtha of the reforming unit pre-fractionation tower and the aromatic raffinate oil.

[0019] Optionally, the method further comprises: sequentially performing desulfurization regeneration and dehydration regeneration on the desiccant to be regenerated to obtain a regenerated desiccant, and returning the regenerated desiccant to the reactor.

[0020] Optionally, the desulfurization regeneration is carried out under a regeneration atmosphere; the conditions for the desulfurization regeneration include: a temperature of 410-430°C, a pressure of 2.0-3.0MPa, and a treatment time of 4-6h; optionally, the regeneration atmosphere is air; the medium for the dehydration regeneration is a C5 / C6 isomerization product; the conditions for the dehydration regeneration include: a temperature of 310-330°C, a pressure of 2.0-3.0MPa, and a treatment time of 4-6h; optionally, the regeneration atmosphere is air.

[0021] Through the above technical scheme, the desiccant provided by the present invention can combine the two processes of desulfurization and drying into one. The material containing hydrogen sulfide and water can be desulfurized to less than 0.1 μg / g by passing through the 13X molecular sieve desiccant of the present invention that takes into account the desulfurization performance, so as to meet the control index of the low-temperature C5 / C6 isomerization catalyst for the hydrogen sulfide and water content in the raw material to be less than 0.1 μg / g, thereby ensuring that the low-temperature isomerization catalyst exerts the best isomerization performance. The 13X molecular sieve desiccant that takes into account the desulfurization performance of the present invention also has good regeneration performance, and the number of regenerations can be guaranteed to be more than 300 times. The desiccant of the present invention is mainly used in the refining process of low-temperature C5 / C6 isomerization raw materials.

[0022] Other features and advantages of the present disclosure will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0023] The specific embodiments of the present disclosure are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure, and are not used to limit the present disclosure.

[0024] A first aspect of the present disclosure provides a desiccant having both desulfurization performance and comprising a carrier and an active metal component loaded on the carrier; the carrier contains a 13X molecular sieve, and the active metal component comprises zinc oxide.

[0025] The desiccant provided by the present disclosure can combine the two processes of desulfurization and drying into one. The material containing hydrogen sulfide and water passes through the 13X molecular sieve desiccant with both desulfurization performance of the present invention, and both hydrogen sulfide and water in the material can be removed to less than 0.1 μg / g, meeting the control index that the content of hydrogen sulfide and water in the raw material is less than 0.1 μg / g for the low-temperature C5 / C6 isomerization catalyst, so as to ensure that the low-temperature isomerization catalyst exhibits the best isomerization performance.

[0026] According to the present disclosure, based on the total weight of the desiccant, the content of 13X molecular sieve in the desiccant can be 99.8 - 80% by weight, preferably 99.5 - 95% by weight; the content of zinc oxide can be 0.2 - 20% by weight, preferably 0.5 - 5% by weight.

[0027] According to the present disclosure, the preparation method of the desiccant with both desulfurization performance includes:

[0028] Immersing spherical 13X molecular sieve in Zn(NO3)2 solution to obtain the impregnated material; performing the first drying treatment and the first calcination treatment on the impregnated material; or,

[0029] Mixing powdered 13X molecular sieve with ZnO, adding a binder and rolling into balls or extruding into strips to obtain the formed material, and performing the second drying treatment and the second calcination treatment on the formed material; or,

[0030] Mixing sodium hydroxide and water evenly, then adding sodium silicate and sodium aluminate in sequence and stirring to obtain the first mixed material; subjecting the first mixed material to aging treatment, then mixing with Zn(NO3)2 and performing crystallization treatment to obtain the second material; filtering and washing the second material and then performing the third drying treatment.

[0031] According to the present disclosure, the conditions of the impregnation treatment can include: temperature is 50 - 70 °C, time is 3 - 6 h; the conditions of the first drying treatment can include: temperature is 110 - 130 °C, time is 3 - 6 h; the conditions of the first calcination treatment can include: temperature is 530 - 560 °C, time is 3 - 6 h.

[0032] According to the present disclosure, the conditions of the second drying treatment can include: temperature is 110 - 130 °C, time is 3 - 6 h; the conditions of the second calcination treatment can include: temperature is 530 - 550 °C, time is 3 - 6 h.

[0033] According to the present disclosure, the molar ratio of SiO2:Na2O:Al2O3:H2O in the first mixed material may be 2.5-3.4:2.8-3.5:1:100-300; the mass ratio of the first material after aging treatment to Zn(NO3)2 may be 90-94:6-10; the conditions for the aging treatment may include agitation treatment, and the time for the agitation treatment may be 20-30; the conditions for the crystallization treatment may include: a temperature of 90-100 °C and a time of 12-24 h; the conditions for the third drying treatment may include: a temperature of 110-120 °C and a time of 10-12 h.

[0034] The second aspect of the present disclosure provides a method for desulfurization and dehydration of a C5 / C6 isomerization feedstock, the method comprising: contacting the C5 / C6 isomerization feedstock with a desiccant in a reactor to obtain a desulfurized and dehydrated C5 / C6 isomerization feedstock and a spent desiccant.

[0035] According to the present disclosure, the content of hydrogen sulfide in the C5 / C6 isomerization feedstock may be not higher than 0.5 μg / g, the water content may be not higher than 10 μg / g, the nitrogen content may be not higher than 0.1 μg / g, the chlorine content may be not higher than 0.5 μg / g, and the content of benzene and components above C7 may be not higher than 3%; the C5 / C6 isomerization feedstock may be selected from at least one of the overhead naphtha from the debutanizer, the light naphtha from the top of the pre-fractionation column of the reforming unit, and the aromatics raffinate.

[0036] According to the present disclosure, the method may further comprise: subjecting the spent desiccant to desulfurization regeneration and dehydration regeneration in sequence to obtain a regenerated desiccant, and returning the regenerated desiccant to the reactor.

[0037] The 13X molecular sieve desiccant of the present disclosure that takes into account desulfurization performance also has good renewable performance, and the number of regeneration times can be guaranteed to be more than 300 times.

[0038] According to the present disclosure, the desulfurization regeneration may be carried out in a regeneration atmosphere; the conditions for the desulfurization regeneration may include: a temperature of 410-430 °C, a pressure of 2.0-3.0 MPa, and a treatment time of 4-6 h; optionally, the regeneration atmosphere may be air; the medium for the dehydration regeneration may be the C5 / C6 isomerization product; the conditions for the dehydration regeneration may include: a temperature of 310-330 °C, a pressure of 2.0-3.0 MPa, and a treatment time of 4-6 h; optionally, the regeneration atmosphere may be air.

[0039] The desiccant of the present disclosure is mainly applied to the refining process of low-temperature C5 / C6 isomerization raw materials. The catalyst used in the low-temperature C5 / C6 isomerization technology is a chlorinated alumina catalyst, and the reaction conditions are 120-210 °C, 1.6-3.5 MPa, liquid hourly space velocity of 1-5 h -1 , and a hydrogen / hydrocarbon molar ratio of 0.02-6. The C5 / C6 isomerization catalyst described above can be well-known to those skilled in the art. For example, it can be a catalyst with bifunctional hydrogenation and isomerization, and this catalyst is composed of 0.01 mass% to 2.0 mass% of Group VIII metals and chlorinated alumina. Optionally, the hydrogenation component of the isomerization catalyst is platinum or palladium or nickel of Group VIII metals, and preferably platinum of Group VIII metals.

[0040] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereby.

[0041] Example 1

[0042] The raw material of this example is commercially available spherical 13X molecular sieve, and its adsorption performance is: under the conditions of 25 °C and a relative humidity of 50%, the H2O adsorption amount of 100 g of 13X molecular sieve is greater than 28 mass%. The 13X molecular sieve is dried at 120 °C for 4 h, cooled in a dryer, 100 g of the above-mentioned 13X molecular sieve and 500 mL of 3 mass% Zn(NO3)2 solution are statically impregnated at 60 °C for 6 h, filtered, dried at 120 °C for h, and calcined at 500 °C for 4 h to obtain the 13X molecular sieve desiccant containing 8 mass% ZnO in this example. The desiccant prepared in this example is marked as ZnO-13X-A.

[0043] Example 2

[0044] The raw material of this example is commercially available powdered 13X molecular sieve, and its adsorption performance is: under the conditions of 25 °C and a relative humidity of 50%, the H2O adsorption amount of 100 g of 13X molecular sieve is greater than 29 mass%. It is dried at 120 °C for 4 h, 200 g of the above-mentioned 13X molecular sieve and 16 g of ZnO are mixed evenly, and an appropriate amount of binder is added to form spheres or extruded bars, dried at 120 °C for 4 h, and calcined at 500 °C for 4 h to obtain the 13X molecular sieve desiccant containing 8 mass% ZnO in this example. The shape of the desiccant prepared in the example is a sphere with a diameter of 2 mm or an extruded bar with a diameter of 2 mm, and it is marked as ZnO-13X-B.

[0045] Example 3

[0046] Prepare the materials according to the molar ratio of SiO2:Na2O:Al2O3:H2O in the mixed first material of 2.8:3.4:1:200. First, mix 133.4 g of 30% NaOH solution and 4955.0 g of deionized water. Then add 1016.0 g of sodium silicate and 1188.5 g of sodium aluminate in sequence and stir well to obtain the mixed first material. After aging the first material at room temperature for 24 hours, mix it with Zn(NO3)2 and perform crystallization treatment. The mass ratio of the first material after aging and Zn(NO3)2 is 92:8. The conditions of the crystallization treatment are: crystallize at 90-100°C in a static state for 12-24 hours, and then filter and wash to a pH value of about 10. The synthesized sample was placed in a drying oven and dried at 110°C for about 12 hours. After molding, a 13X molecular sieve desiccant with desulfurization performance was obtained, which was marked as ZnO-13X-C.

[0047] Example 4

[0048] Weigh 10 g of ZnO-13X-A prepared in the present disclosure and place it in a stainless steel reactor with a diameter of 20 mm. After nitrogen replacement, the reactor is heated to room temperature with a mass space velocity of 5 h -1 At 3.0 MPa, a C5 / C6 isomerized feedstock oil containing 0.5 μg / g hydrogen sulfide and 10 μg / g water was injected into the reactor by a high-pressure pump. The sulfur and water content in the reaction product was analyzed every 20 hours. The total reaction time was 150 hours. The test results are shown in Table 1.

[0049] Example 5

[0050] Weigh 10 g of ZnO-13X-B prepared in the present disclosure and place it in a stainless steel reactor with a diameter of 20 mm. After nitrogen replacement, the reactor is heated to room temperature with a mass space velocity of 5 h -1 At 3.0 MPa, a C5 / C6 isomerized feedstock oil containing 0.5 μg / g hydrogen sulfide and 10 μg / g water was injected into the reactor by a high-pressure pump. The sulfur and water content in the reaction product was analyzed every 20 hours. The total reaction time was 150 hours. The test results are shown in Table 1.

[0051] Example 6

[0052] Weigh 10 g of ZnO-13X-C prepared in the present disclosure and place it in a stainless steel reactor with a diameter of 20 mm. After nitrogen replacement, the reactor is heated to room temperature with a mass space velocity of 5 h -1 At 3.0 MPa, a C5 / C6 isomerized feedstock oil containing 0.5 μg / g hydrogen sulfide and 10 μg / g water was injected into the reactor by a high-pressure pump. The sulfur and water content in the reaction product was analyzed every 20 hours. The total reaction time was 150 hours. The test results are shown in Table 1.

[0053] Table 1

[0054]

[0055] As can be seen from the data in Table 1, the ZnO-13X molecular sieve desiccants prepared by the present disclosure all have good desulfurization and dehydration effects.

[0056] Example 7

[0057] Perform desulfurization regeneration treatment on ZnO-13X molecular sieve. The desulfurization regeneration treatment conditions are as follows: medium: air; volume space velocity: 100:1; temperature: 420 °C; pressure: 3.0 MPa; treatment time: 4 - 6 h. Monitor the sulfur dioxide content in the outlet gas in real time. When there is no sulfur dioxide content in the outlet of the detection tube, the desulfurization regeneration ends. Subsequently, perform dehydration regeneration treatment on ZnO-13X molecular sieve. The dehydration regeneration conditions are as follows: medium: C5 / C6 isomerization raw material with water content lower than 1 μg / g; volume space velocity: 100:1, inlet temperature controlled at: 330 °C; pressure: 3.0 MPa; treatment time: 4 - 6 h. When the reactor outlet temperature reaches 320 °C, the dehydration treatment ends. After cooling, the regenerated desiccant is obtained, and the regenerated one can be used continuously in the desulfurization and dehydration processes.

[0058] The preferred embodiments of the present disclosure have been described in detail above. However, the present disclosure is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0059] In addition, it should be noted that, in the case of no contradiction, the various specific technical features described in the above specific embodiments can be combined in any appropriate manner. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combination methods.

[0060] In addition, any combination can be made between various different embodiments of the present disclosure, as long as it does not violate the idea of the present disclosure, it should also be regarded as the content disclosed by the present disclosure.

Claims

1. A method for desulfurization and dehydration of C5 / C6 isomerization feedstock, characterized in that, The method includes: contacting a C5 / C6 isomerization feedstock with a desiccant in a reactor to obtain a C5 / C6 isomerization feedstock after desulfurization and dehydration and a spent desiccant; The desiccant includes a carrier and an active metal component supported on the carrier; the carrier contains 13X molecular sieve, and the active metal component includes zinc oxide; the content of 13X molecular sieve in the desiccant is 92.0 - 95 wt%, and the content of zinc oxide is 5 - 8.0 wt%; The content of hydrogen sulfide in the C5 / C6 isomerization feedstock is not higher than 0.5 μg / g, the water content is not higher than 10 μg / g, the nitrogen content is not higher than 0.1 μg / g, the chlorine content is not higher than 0.5 μg / g, and the content of benzene and components above C7 is not higher than 3%; the method further includes: subjecting the spent desiccant to desulfurization regeneration and dehydration regeneration in sequence to obtain a regenerated desiccant, and returning the regenerated desiccant to the reactor; the desulfurization regeneration is carried out in a regeneration gas atmosphere; the conditions for the desulfurization regeneration include: temperature of 410 - 430 °C, pressure of 2.0 - 3.0 MPa, and treatment time of 4 - 6 h; the regeneration gas atmosphere is air; The preparation method of the desiccant includes: Immersing spherical 13X molecular sieve in a Zn(NO3)2 solution to obtain an impregnated material; subjecting the impregnated material to a first drying treatment and a first calcination treatment; the conditions for the impregnation treatment include: temperature of 50 - 70 °C and time of 3 - 6 h; the conditions for the first drying treatment include: temperature of 110 - 130 °C and time of 3 - 6 h; the conditions for the first calcination treatment include: temperature of 530 - 560 °C and time of 3 - 6 h; or, Mixing powdered 13X molecular sieve with ZnO, adding a binder, and forming by rolling into balls or extruding into strips to obtain a formed material, and subjecting the formed material to a second drying treatment and a second calcination treatment; or, Mixing sodium hydroxide and water uniformly, then adding sodium silicate and sodium aluminate in sequence and stirring to obtain a first mixed material; subjecting the first mixed material to an aging treatment, then mixing with Zn(NO3)2 and performing a crystallization treatment to obtain a second material; filtering and washing the second material and then performing a third drying treatment.

2. The method according to claim 1, wherein The conditions for the second drying treatment include: temperature of 110 - 130 °C and time of 3 - 6 h; the conditions for the second calcination treatment include: temperature of 530 - 550 °C and time of 3 - 6 h.

3. The method according to claim 1, wherein The molar ratio of SiO2:Na2O:Al2O3:H2O in the first mixed material after mixing is 2.5 - 3.4:2.8 - 3.5:1:100 - 300; the mass ratio of the first material after aging treatment to Zn(NO3)2 in the mixing is 90 - 94:6 - 10; The conditions for the aging treatment include a stirring treatment, and the time of the stirring treatment is 20 - 30 h; The conditions for the crystallization treatment include: temperature of 90 - 100 °C and time of 12 - 24 h; the conditions for the third drying treatment include: temperature of 110 - 120 °C and time of 10 - 12 h.

4. The method according to claim 1, wherein The C5 / C6 isomerization feedstock is selected from at least one of the overhead naphtha from the debutanizer, the light naphtha from the top of the pre-fractionating column of the reforming unit, and the aromatics raffinate.

5. The method according to claim 1, wherein The medium for dehydration regeneration is the C5 / C6 isomerization product; The conditions for dehydration regeneration include: a temperature of 310 - 330 °C, a pressure of 2.0 - 3.0 MPa, and a treatment time of 4 - 6 h.

6. The method according to claim 1, wherein, The atmosphere for dehydration regeneration is air.

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