CN108018075B

CN108018075B - Gasoline desulfurization method and gasoline desulfurization device

Info

Publication number: CN108018075B
Application number: CN201610930944.8A
Authority: CN
Inventors: 刘锋; 褚阳; 李明丰; 李会峰; 习远兵
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2016-10-31
Filing date: 2016-10-31
Publication date: 2020-04-28
Anticipated expiration: 2036-10-31
Also published as: CN108018075A

Abstract

The invention relates to the field of hydrogenation processA method and apparatus for desulfurizing gasoline is disclosed, the method comprising: (1) in the presence of hydrogen, gasoline fraction and selective hydrodesulfurization catalyst are subjected to a first contact reaction, and reaction products are separated to obtain a product containing H₂S、H₂The gas and hydrogenated fraction a of (a); (2) carrying out a second contact reaction on the hydrogenated fraction a obtained in the step (1) and a selective mercaptan removal catalyst to obtain a reaction product b; (3) the reaction product b was stripped. The method for desulfurizing the gasoline provided by the invention has simple process, and can realize effective removal of sulfur in the gasoline under the condition of lower olefin saturation even under the conditions of lower reaction temperature and reaction pressure and the presence of hydrogen sulfide.

Description

Gasoline desulfurization method and gasoline desulfurization device

Technical Field

The invention relates to the field of hydrogenation processes, in particular to a gasoline desulfurization method and a gasoline desulfurization device.

Background

At present, air pollution causes more and more serious environmental problems, and tail gas emitted by automobile engines becomes a main source of urban air pollution. SO is generated after sulfur in gasoline is combusted_xThe method has the advantages that severe pollution is caused to air, strict limits are provided for the sulfur content in gasoline in all countries of the world, the step of limiting the sulfur content in gasoline in China is gradually accelerated, the clean gasoline standard similar to the European III emission standard is implemented at the end of 2009, the clean gasoline standard similar to the European IV emission standard is implemented in 2014 nationwide, the clean gasoline emission standard similar to the European V emission standard is implemented in 2017 nationwide, and the sulfur content in the gasoline cannot be higher than 10 mug/g. Under the background, researchers develop clean gasoline production technologyTo meet the market demand.

In China, the proportion of the catalytic cracking gasoline in a gasoline pool is relatively high, and the sulfur content of the catalytic cracking gasoline is high, so that the removal of sulfur in the catalytic cracking gasoline is the most urgent problem. The most difficult sulfur in the catalytically cracked gasoline is thiophene sulfide, and the sulfur can be removed by improving the hydrogenation reaction conditions in the prior art, but the catalytically cracked gasoline contains a large amount of olefins which are high-octane components in the gasoline, and the severe hydrogenation reaction conditions easily cause olefin saturation and octane number loss, so that the olefin saturation is reduced to the maximum extent while the sulfide in the catalytically cracked gasoline is removed.

Researchers found that in the process of producing clean gasoline with sulfur content less than 10 mug/g, the remaining sulfides which are not completely removed are mainly thiol compounds, the thiol compounds are generated by addition reaction of hydrogen sulfide generated after thiophene hydrodesulfurization and olefins in gasoline, the reaction is a reversible reaction which is difficult to remove due to thermodynamic equilibrium, and if a conventional hydrodesulfurization catalyst is used to remove thiols, very harsh reaction conditions are required, which inevitably causes a great loss of octane number.

US6231754B1 discloses a process for mercaptan removal from naphtha by mercaptan decomposition with a partially deactivated catalyst (2-40% active as fresh catalyst) at high reaction temperature, which can exert the catalyst activity at high reaction temperature (305 ℃ and 455 ℃) without olefin hydrogenation saturation and has better selectivity for mercaptan removal. The disclosed method has the disadvantages of high reaction temperature, high investment and energy consumption of the device.

US6387249B1 discloses a process for removing mercaptans from naphtha by decomposing mercaptans from naphtha using a CoMo catalyst under conditions of high reaction temperature and low reaction pressure, the high reaction temperature being thermodynamically favorable for removal of mercaptans and suppression of the regeneration reaction of mercaptans, and the low reaction pressure being favorable for suppression of the regeneration reaction of mercaptans. The disclosed method has the disadvantages of high reaction temperature, high investment and energy consumption of the device.

Although the prior art can remove sulfur in gasoline to a certain extent, the prior art has the defects of high olefin saturation rate and harsh reaction conditions, and therefore, a method and a device which have low olefin saturation rate and can effectively remove sulfur in gasoline under mild reaction conditions are urgently needed to be developed.

Disclosure of Invention

The invention provides a novel gasoline desulfurization method and a gasoline desulfurization device aiming at the defects of harsh reaction conditions and high olefin saturation rate in the gasoline desulfurization process in the prior art.

The invention provides a method for desulfurizing gasoline, which comprises the following steps:

(1) in the presence of hydrogen, gasoline fraction and selective hydrodesulfurization catalyst are subjected to a first contact reaction, and reaction products are separated to obtain a product containing H₂S、H₂The gas and hydrogenated fraction a of (a);

(2) carrying out a second contact reaction on the hydrogenated fraction a obtained in the step (1) and a selective mercaptan removal catalyst to obtain a reaction product b;

(3) the reaction product b was stripped.

The invention also provides a gasoline desulfurization device, which comprises: the selective hydrodesulfurization reactor, the high-pressure separator, the selective mercaptan removal reactor and the stripping tower are sequentially connected through pipelines; the high-pressure separator is used for carrying out gas-liquid separation on the material at the outlet of the selective hydrodesulfurization reactor, and the liquid enters the selective sweetening reactor; stripping column for stripping H formed in selective mercaptan removal reactor₂S。

By adopting the method provided by the invention, the H generated in the step (1) is used before the step (2)₂S is removed, and H is prevented from being generated in the reaction process of the step (2)₂S and olefin are further reacted to generate thiol substances; in the step (2), the hydrogenated fraction a reacts with a selective mercaptan removal catalyst to generate H₂S, the reaction product b is stripped and steamed through the step (3) in the inventionBy providing H₂S and reduction of H with selective sweetening catalyst₂Probability of producing thiol species by reacting S with olefin.

The method provided by the invention can effectively reduce the sulfur content in the gasoline on the premise of low olefin saturation even under mild reaction conditions.

The inventor of the present invention found in the course of further research that, in a preferred case, when the atomic ratio of the active metal component a to the sum of the active metal component a and the active metal component B in the selective sweetening catalyst is 0.3 or more and the content of the class ii active phase a-B-S is 55% or more, the selective sweetening catalyst has more excellent selectivity, that is, the gasoline sweetening rate is further increased under the condition of lower olefin saturation rate.

In addition, the present invention provides that even small amounts of H are present in step (2) of the process₂S is present and can also achieve the aim of the invention, while the prior art provides a method for adding H by adopting a stripping medium₂And (4) stripping and removing S.

Compared with the prior art, the device for gasoline desulfurization provided by the invention has the advantages that the selective mercaptan removal reaction and the stripping operation are carried out in different units, and the defects that the reaction condition of the selective mercaptan removal reaction is not suitable for the stripping operation and the condition of the stripping operation is not suitable for the selective mercaptan removal reaction in the prior art can be overcome.

The method for desulfurizing the gasoline provided by the invention has simple process, and can realize effective removal of sulfur in the gasoline under the condition of lower olefin saturation even under the condition of lower reaction temperature and reaction pressure. The device for gasoline desulfurization provided by the invention can realize effective removal of sulfur in gasoline under a relatively mild condition and a relatively low olefin saturation condition.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a flow diagram of a gasoline desulfurization process as described in example 1.

Detailed Description

The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

(3) the reaction product b was stripped.

The gasoline fraction of the present invention may be any gasoline fraction conventional in the art, preferably the gasoline fraction is a gasoline fraction having a boiling range of 10 to 230 ℃, more preferably a gasoline fraction having a boiling range of 40 to 210 ℃, and may be selected from at least one of catalytically cracked gasoline, coker gasoline, pyrolysis gasoline, and thermally cracked gasoline, for example.

The selective hydrodesulfurization catalyst in step (1) is not particularly limited in the present invention, and may be various selective hydrodesulfurization catalysts commonly used in the art, such as a catalyst comprising a carrier and a group VIB metal component and a group VIII metal component supported on the carrier, where the carrier may be various carriers commonly used in the art, and is preferably alumina.

The conditions for the first contact reaction of the present invention are widely selected, and for example, the conditions for the first contact reaction may include: the reaction temperature is 200-400 ℃, the reaction pressure is 1-5MPa, and the volume space velocity of the gasoline fraction is 1-10h^-1The hydrogen-oil volume ratio is 100-: the reaction temperature is 300-360 ℃, the reaction pressure is 1.2-3.2MPa, and the volume space velocity of the gasoline fraction is 2-8h^-1The volume ratio of hydrogen to oil is 100-600.

According to the method of the present invention, preferably, the separation is gas-liquid separation, and specifically, the separation may be: after the reaction product is subjected to heat exchange and temperature reduction, the temperature is preferably reduced to 30-45 ℃, and the reaction product enters a high-pressure separator for gas-liquid separation to obtain H-containing product₂S、H₂Gas and hydrogenated fraction a. Further preferably, the hydrogenated fraction a is depressurized and then enters a low-pressure separator, and the hydrogen sulfide dissolved in the hydrogenated fraction a is further separated out by using a principle similar to flash evaporation. In the present invention, preferably, the pressure in the low-pressure separator is the same as the second contact reaction pressure.

From the viewpoint of effective utilization of the substance, it is preferable that the separated H-containing substance₂S、H₂Gas removal of H₂And (5) obtaining hydrogen-rich gas after S, and recycling the hydrogen-rich gas to the step (1) for effective utilization.

The invention is directed to said compound containing H₂S、H₂H in the gas of (2)₂The removal of S is not particularly limited, and for example, neutralization and absorption with an alkali substance or adsorption and separation with a metal oxide can be carried out. The basic substance may be an inorganic base and/or an organic base, and the metal oxide may be at least one selected from zinc oxide, nickel oxide, and magnesium oxide.

In the present invention, the conditions for the second contact reaction in step (2) are not particularly limited, and from the viewpoint of reducing energy consumption and protecting equipment, the conditions for the second contact reaction preferably include: the reaction temperature is 90-300 ℃, the reaction pressure is 0.1-4MPa, and the volume space velocity of the hydrogenation fraction a is 0.1-10h^-1(ii) a Further preferably, the conditions of the second contact reaction include: the reaction temperature is 120 ℃ and 280 ℃, the reaction pressure is 0.1-2MPa, and the volume space velocity of the hydrogenation fraction a is 1-8h^-1(ii) a Even more preferably, the conditions of the second contact reaction include: the reaction temperature is 150 ℃ and 260 ℃, the reaction pressure is 0.3-0.8MPa, and the volume space velocity of the hydrogenation fraction a is 2-8h^-1。

In the prior art, the actual reaction temperature is higher than 260 ℃, under the second contact reaction condition which is preferred by the invention, the method provided by the prior art can not consider lower olefin saturation rate and higher desulfurization rate, and the invention reduces the probability of hydrogenation reaction between hydrogen sulfide and olefin by removing most hydrogen sulfide before the second contact reaction.

It should be noted that the second contact reaction may be carried out in the presence of hydrogen or in the absence of hydrogen, and the participation of hydrogen may serve to dilute the concentration of hydrogen sulfide, but in the present invention, it is preferable that the second contact reaction pressure is low, and if the reaction is carried out in the presence of hydrogen, the hydrogen of the first contact reaction cannot be effectively utilized, and therefore, it is preferable that the second contact reaction is carried out in the absence of hydrogen from the viewpoint of energy saving.

According to a preferred embodiment of the present invention, the selective sweetening catalyst comprises a carrier and an active metal component A and an active metal component B loaded on the carrier, wherein the active metal component A is selected from at least one of the metal elements of the VIII group, the active metal component B is selected from at least one of the metal elements of the VIB group, the active metal component A and the active metal component B exist in a sulfide form, the atomic ratio of the active metal component A to the sum of the active metal component A and the active metal component B in the catalyst is more than 0.3 as measured by X-ray fluorescence spectroscopy, and the content of the active phases A-B-S of the II group in the catalyst is more than 55% as measured by X-ray electron spectroscopy, wherein the content of the active phases A-B-S of the II group refers to the presence of the active metal component A in the active phases A-B-S of the II group as measured by X-ray electron spectroscopy The ratio of the amount of (A) to the total amount of the active metal component (A).

The preferred catalyst has higher desulfurization selectivity, i.e. the desulfurization rate of gasoline is further improved under the condition of lower olefin saturation rate, and the preferred catalyst can technically allow the second contact reaction of the step (2) to be carried out in H₂S is present, whereas in the prior art H is formed as a result of the removal of sulfur from the hydrogenated fraction a₂S, and H₂S reacts with olefin in the hydrogenated fraction a to generate mercaptan substances, which are not beneficial to effectively removing sulfide, so that the method adopted in the prior art is to generate H₂S is completely removed, but the step has higher difficulty and higher energy consumption in actual production, and H is treated by adopting the catalyst provided by the invention₂The limitation of the S concentration is small.

Therefore, the second contact reaction in step (2) is preferably performed in H₂In the presence of S. The preferred embodiment has simple process steps and is suitable for industrial application.

According to the method of the present invention, it is understood that H in the present invention₂S and gasoline move along the same direction of the catalyst bed, while in the prior art, the stripping and mercaptan removal reactions are carried out in the same reactor, H₂S and gasoline move along the catalyst bed in the opposite direction, gasoline moves towards the bottom of the tower, H₂S moves to the top of the tower.

In the present invention, preferably, the active metal component a is a cobalt and/or nickel element, and the active metal component B is a molybdenum and/or tungsten element, and in order to further improve the desulfurization activity and selectivity of the catalyst, it is further preferable that the active metal component a is a cobalt element, and the active metal component B is a molybdenum element.

The carrier is not particularly limited in the present invention, and may be any of various carriers commonly used in the art, and may be commercially available or may be prepared by any of the methods known in the art, and in order to further improve the desulfurization activity and selectivity of the hydrogenation catalyst, it is preferable that the carrier is a heat-resistant inorganic oxide.

Preferably, the heat-resistant inorganic oxide is selected from one or more of alumina, silica, titania, magnesia, silica-alumina, silica-magnesia, alumina-zirconia, silica-thoria, silica-beryllia, silica-titania, silica-zirconia, titania-zirconia, silica-alumina-thoria, silica-alumina-titania, silica-alumina-magnesia, silica-alumina-zirconia, most preferably alumina.

In the context of the present invention, the class II active phase A-B-S is the active center of the hydrogenation catalyst, the concept being proposed by Haldor Topsoe in 1984. In the hydrogenated catalyst after being vulcanized, VIII group metal elements exist in different forms, for example, Co is taken as an example, in the vulcanized CoMo catalyst, Co is respectively Co²⁺Co-Mo-S and Co₉S₈The Co existing in different forms corresponds to peaks at different positions in the XPS spectrogram, and the Co is calculated by unfolding the peaks²⁺Co-Mo-S and Co₉S₈Corresponding peak area by Co-Mo-S corresponding peak area/(Co)²⁺Corresponding peak area + Co-Mo-S corresponding peak area + Co₉S₈Corresponding peak area) x 100%, the content of the II-type active phase Co-Mo-S is calculated, and the method is also suitable for NiW catalysts. The specific calculation method can be found in Qielimei article (X-ray photoelectron spectroscopy is used to study the chemical state of active elements in hydrodesulfurization catalyst [ J]And petroleum science and newspaper: petroleum processing, 2011, 27 (4): 638-642).

In the present invention, without particular reference, X-ray photoelectron spectroscopy (XPS) was carried out on an ESCALab 250 type X-ray photoelectron spectrometer (VG, UK) using a radiation source of Al K α, a resolution of 0.5eV, and an internal standard of C1s binding energy (Eb 285.0eV) of contaminated carbon.

In the present invention, the atomic ratio of the active metal component A to the sum of the active metal component A and the active metal component B is given by the result of X-ray fluorescence spectrum analysis.

In the present invention, X-ray fluorescence spectroscopy (XRF) analysis was carried out using a ZSX-100e type X-ray fluorescence spectrometer using an Rh target at a current of 50mA and a voltage of 50kV, unless otherwise specified.

According to a preferred embodiment of the present invention, the atomic ratio of the active metal component a to the sum of the active metal component a and the active metal component B is 0.3 to 0.7, more preferably 0.4 to 0.7, most preferably 0.4 to 0.6; the content of the active phase A-B-S of group II is 55 to 95%, more preferably 60 to 90%, most preferably 70 to 80%. With this preferred embodiment, the hydrodesulfurization activity and selectivity of the catalyst can be further improved.

The atom ratio of the active metal component A to the sum of the active metal component A and the active metal component B in the selective sweetening catalyst disclosed in the prior art is less than 0.3, and the content of the active phase A-B-S in the II class is below 50 percent, and is mostly between 40 and 50 percent.

According to the method provided by the invention, the content of the carrier is preferably 70-97 wt%, more preferably 79-93 wt% based on the total weight of the selective mercaptan removal catalyst; the content of the active metal component A is 1 to 10% by weight, more preferably 1 to 6% by weight, and the content of the active metal component B is 2 to 20% by weight, more preferably 6 to 15% by weight, in terms of oxide.

The present invention is not particularly limited to the method for preparing the above selective sweetening catalyst, and any method that can provide the selective sweetening catalyst with the above structural features may be used in the present invention, and preferably, the method for preparing the above selective sweetening catalyst comprises: (a) impregnating the carrier with a solution containing a precursor of the active metal component A and a precursor of the active metal component B; (b) vulcanizing the solid material obtained after impregnation in the step (a); wherein, the mol ratio of the precursor of the active metal component A to the precursor of the active metal component B is 0.6-2.3: 1; the precursor of the active metal component B is ammonium thiosulfate.

The selection of the active metal component A, the active metal component B and the carrier in the invention is as described above, and the details are not repeated here.

In the present invention, preferably, when the active metal component B is molybdenum element, the precursor of the active metal component B is ammonium thiomolybdate; when the active metal component B is tungsten element, the precursor of the active metal component B is ammonium thiotungstate.

According to the method provided by the invention, preferably, the active metal component B is molybdenum element, and the precursor of the active metal component B is ammonium thiomolybdate.

According to the present invention, the impregnation method in step (a) is not particularly limited, and a co-impregnation method or a step-by-step impregnation method may be employed, i.e., the precursor of the active metal component a and the precursor of the active metal component B may be prepared as a solution to impregnate the carrier together, or a solution containing the precursor of the active metal component a may be impregnated into the carrier first, then dried, and then impregnated with a solution containing the precursor of the active metal component B, and similarly, the active metal component B may be impregnated first and then the active metal component a may be impregnated. The invention preferably prepares a precursor solution containing an active metal component B to impregnate the carrier, dries the carrier, and then adopts the precursor solution containing the active metal component A to impregnate the carrier.

The impregnation conditions in step (a) of the present invention are not particularly limited, and may be, for example, impregnation at room temperature for 4 to 8 hours.

In order to further improve the desulfurization activity and selectivity of the catalyst, the concentration of the precursor of the active metal component B in the solution in step (a) is preferably 0.05 to 1.5mol/L, more preferably 0.12 to 1.12mol/L, and still more preferably 0.45 to 1.12 mol/L.

According to the invention, the molar ratio of the precursor of the active metal component a to the precursor of the active metal component B is preferably 0.6 to 1: 1, more preferably 0.6 to 0.8: 1. with this preferred embodiment, it is more beneficial to increase the atomic ratio of the active metal component a to the sum of the active metal component a and the active metal component B of the catalyst produced.

In order to further improve the desulfurization activity and selectivity of the catalyst, it is preferable that the solution in the step (a) further contains an organic complexing agent. The presence of the organic complexing agent can control the size of the metal active phase to a certain extent, and in the subsequent vulcanization process, the active metal component A is promoted to be vulcanized after the active metal component B, so that the active metal component A can more easily exert the auxiliary effect.

In the present invention, it is preferable that the molar ratio of the organic complexing agent to the precursor of the active metal component B in terms of the metal element is 0.5 to 1.5: 1, more preferably 0.6 to 1.2: 1.

the organic complexing agent can be prepared into a solution impregnation carrier together with a precursor of the active metal component A and a precursor of the active metal component B, can also be prepared into a solution impregnation carrier together with the precursor of the active metal component A or the precursor of the active metal component B, and can also be independently prepared into a solution impregnation carrier. The organic complexing agent is preferably introduced by formulating it into a solution with the precursor of the active metal component a.

The type of the organic complexing agent is not particularly limited in the present invention, and may be various organic complexing agents used in the preparation process of the hydrogenation catalyst, and for example, the organic complexing agent may be at least one selected from the group consisting of citric acid, ethylenediaminetetraacetic acid (EDTA), ethylene glycol, glycerol, and nitrilotriacetic acid.

In the present invention, the solid material of step (b) can be obtained by drying the mixed material obtained by the impregnation of step (a), the drying conditions are not particularly limited, and the drying can be performed in a conventional manner in the art, and preferably the drying is vacuum drying. For example, the temperature of the vacuum drying may be 60 to 150 ℃ and the time may be 2 to 10 hours.

In the present invention, the vulcanization mode in the step (b) is not particularly limited, and may be dry (gas phase) vulcanization or wet (liquid phase) vulcanization.

If dry vulcanization is adopted, the dry vulcanization can be specifically as follows: carrying out contact reaction on a sulfur-containing medium and the solid material obtained in the step (a).

According to a preferred embodiment of the present invention, the sulfur-containing medium is a mixed gas containing hydrogen and hydrogen sulfide, preferably, the mixed gas has a hydrogen sulfide content of 0.1 to 10 vol%, a hydrogen content of 90 to 99.9 vol%, further preferably, a hydrogen sulfide content of 1 to 5 vol%, a hydrogen content of 95 to 99 vol%, more preferably, a hydrogen sulfide content of 1 to 3 vol%, and a hydrogen content of 97 to 99 vol%.

In the present invention, the mixed gas may further contain an inert gas, and preferably, the mixed gas contains 0.1 to 10 vol% of hydrogen sulfide, 10 to 30 vol% of hydrogen, and 60 to 89.9 vol% of an inert gas, and further preferably, contains 1 to 3 vol% of hydrogen sulfide, 20 to 30 vol% of hydrogen, and 67 to 79 vol% of an inert gas.

In the present invention, the inert gas may be one or more selected from nitrogen, argon, helium, carbon dioxide and water vapor, preferably one or more selected from nitrogen, argon and helium, and more preferably nitrogen.

In the present invention, the conditions of the contact reaction in the dry vulcanization are not particularly limited, and preferably the conditions of the contact reaction include: the temperature is 20-400 ℃, the pressure is 0.1-20MPa, the time is 1-48h, and the volume ratio of the gas agent is 10-1000; further preferably, the temperature is 100-400 ℃, the pressure is 0.1-10MPa, the time is 5-24h, and the volume ratio of the gas agent is 20-500; more preferably, the temperature is 300-350 ℃, the pressure is 0.1-3.2MPa, the time is 5-10h, and the volume ratio of the gas agent is 50-400.

If wet vulcanization is employed, the wet vulcanization may specifically be: and (b) carrying out contact reaction on the vulcanized oil containing the vulcanizing agent and the solid material obtained in the step (b) in the presence of hydrogen.

In the present invention, the vulcanizing agent is selected from a wide range, and may be, for example, at least one of elemental sulfur, inorganic sulfur compounds, mercaptans, sulfides, disulfides and polysulfides, which are generally used in the art.

In the present invention, the content of the vulcanizing agent is not particularly limited as long as sufficient vulcanization of the catalyst is satisfied, and the content of the vulcanizing agent is preferably 2 to 10 parts by weight, and more preferably 2 to 5 parts by weight, relative to 100 parts by weight of the vulcanizing oil containing the vulcanizing agent.

In the present invention, the selection range of the vulcanized oil is wide, and for example, the vulcanized oil can be selected from at least one of gasoline distillate, aviation kerosene distillate and diesel oil distillate, preferably selected from at least one of straight-run gasoline distillate, straight-run aviation kerosene distillate and straight-run diesel oil distillate, and more preferably selected from straight-run gasoline distillate; the vulcanized oil can also be selected from at least one of organic hydrocarbon substances with carbon number of 5-18, preferably from at least one of organic hydrocarbon substances with carbon number of 6-12, and more preferably cyclohexane and/or n-heptane.

In the present invention, the conditions of the contact reaction in the wet vulcanization are not particularly limited, and preferably the conditions of the contact reaction include: the temperature is 20-400 ℃, the pressure is 0.1-20MPa, the time is 1-48h, and the space velocity of hydrogen volume is 5-10000h^-1The volume ratio of hydrogen to oil is 10-1000; further preferably, the temperature is 100-^-1The volume ratio of hydrogen to oil is 20-500; more preferably, the temperature is 300-350 ℃, the pressure is 1.6-3.2MPa, the time is 5-10h, and the hydrogen volume space velocity is 300-1600h^-1The volume ratio of hydrogen to oil is 50-400.

In the present invention, wet vulcanization is preferably employed. The preferred embodiment can effectively control the size of the metal active phase, thereby further improving the activity and selectivity of the selective mercaptan removal catalyst.

The stripping in step (3) of the gasoline desulfurization method of the present invention is not particularly limited, and can be performed according to the conventional technical means in the field, and preferably, the stripping of the reaction product b in step (3) comprises: introducing the reaction product b into a stripping tower, and stripping H from the top of the stripping tower₂S and H₂And distilling the gasoline product from the bottom of the tower.

It should be noted that the preferred step (2) of the present invention is carried out in the absence of hydrogen, in which case it is not excluded that a small amount of hydrogen is dissolved in the hydrogenated fraction a, so that a small amount of H is stripped off at the top of the column₂。

According to the invention, the reaction product b is preferably cooled to 90-150 ℃ by heat exchange and then enters a stripping tower.

The invention provides a device for desulfurizing gasoline,as shown in fig. 1, the apparatus includes: a selective hydrodesulfurization reactor 1, a high-pressure separator 4, a selective mercaptan removal reactor 2 and a stripping tower 3 which are connected in sequence through pipelines; the high-pressure separator 4 is used for carrying out gas-liquid separation on the material at the outlet of the selective hydrodesulfurization reactor 1, and the liquid enters the selective sweetening reactor 2; the stripping column 3 is used for stripping H formed in the selective mercaptan removal reactor 2₂S。

According to a preferred embodiment of the invention, the apparatus further comprises a low pressure separator 9, the inlet of said low pressure separator 9 being in communication with the liquid outlet of the high pressure separator 4, the outlet of the low pressure separator 9 being in communication with the inlet of the selective sweetening reactor 2, said low pressure separator 9 being adapted to separate hydrogen sulphide dissolved in the liquid.

According to a preferred embodiment of the invention, the apparatus further comprises a compressor 7, the inlet of said compressor 7 being in communication with the gas outlet of the high-pressure separator 4, the outlet of the compressor 7 being in communication with the inlet of the selective hydrodesulfurization reactor 1.

According to a preferred embodiment of the invention, the apparatus further comprises a de-H unit₂S reactor 10, removal of H₂The inlet of the S reactor 10 is communicated with the gas outlet of the high-pressure separator 4 for removing H₂The outlet of the S reactor 10 is communicated with the inlet of the compressor 7, and the H removal is carried out₂The S reactor 10 is used for removing H in the gas at the outlet of the high-pressure separator 4₂S。

According to a preferred embodiment of the present invention, the apparatus further comprises a first heat exchanger 5, a second heat exchanger 6 and a third heat exchanger 8, the first heat exchanger 5 is installed on the communicating pipe of the selective hydrodesulfurization reactor 1 and the high pressure separator 4, the second heat exchanger 6 is installed on the communicating pipe of the high pressure separator 4 and the selective sweetening reactor 2, and the third heat exchanger 8 is installed on the communicating pipe of the selective sweetening reactor 2 and the stripping column 3.

According to the invention, the method for desulfurizing the gasoline is preferably carried out on the device for desulfurizing the gasoline provided by the invention. The method and apparatus for desulfurizing gasoline will now be described in detail to make the specific process of the present invention more clear to those skilled in the art, but it should be noted that the following is not intended to limit the present invention.

Mixing gasoline fraction with hydrogen, performing heat exchange to reach a predetermined reaction temperature, introducing into a selective hydrodesulfurization reactor 1 filled with a selective hydrodesulfurization catalyst, performing selective hydrodesulfurization reaction, cooling the reaction product by a first heat exchanger 5, and introducing into a high-pressure separator 4 to realize gas-liquid separation to obtain a product containing H₂S、H₂Gas and hydrogenated fraction a. Containing H₂S、H₂Gas inlet of (2) to remove H₂S reactor 10, removal of H₂And S, obtaining hydrogen-rich gas, compressing the hydrogen-rich gas by a compressor 7, circulating the hydrogen-rich gas back to an inlet of the selective hydrodesulfurization reactor 1 for recycling, reducing the pressure of the hydrogenated fraction a by a pressure reduction device, entering a low-pressure separator 9, flashing to obtain hydrogen sulfide and hydrogen dissolved in the hydrogenated fraction a, heating by a second heat exchanger 6, and entering a selective sweetening reactor 2 filled with a selective sweetening catalyst for selective sweetening reaction to obtain a reaction product b. The reaction product b enters a stripping tower 3 after being cooled by a third heat exchanger 8, and H₂S (containing a small amount of H)₂) And (4) flowing out from the top of the tower, and collecting the generated oil at the bottom of the tower, wherein the generated oil is a qualified gasoline product after mercaptan removal.

It should be noted that, because the pressure ratio of the gas obtained by the flash evaporation of the low-pressure separator 9 is lower and the amount is less, the gas is not recycled, and the gas is directly subjected to the subsequent treatment process.

The method for desulfurizing the gasoline can effectively remove mercaptan in the gasoline under mild conditions, and has low olefin saturation rate, while the catalyst provided by the prior art has high olefin saturation rate, high reaction temperature of over 330 ℃, harsh reaction conditions and difficult process application in the mercaptan removal process.

The following detailed description is provided for the purpose of illustrating the embodiments and the advantageous effects thereof, and is intended to help the reader to clearly understand the spirit of the present invention, but not to limit the scope of the present invention.

In the following preparation examples, the metal content of the selective sweetening catalyst, the atomic ratio of the active metal component A to the sum of the active metal component A and the active metal component B, were measured by X-ray fluorescence spectroscopy (XRF) using a ZSX-100e type X-ray fluorescence spectrometer using an Rh target at a current of 50mA and a voltage of 50 kV.

The content of the II-type active phase A-B-S in the selective sweetening catalyst is obtained by processing XPS data, and the specific processing method can be seen in the chemical state [ J ] of active elements in the hydrodesulfurization catalyst researched by a literature X-ray photoelectron spectroscopy, which is reported in petro Production, 2011, 27 (4): 638-642, wherein the X-ray photoelectron spectroscopy (XPS) is carried out on an ESCA Lab 250 type X-ray photoelectron spectrometer (product of VG company, England) and is obtained under the conditions that a radiation source is Al K α, the resolution is 0.5eV and an internal standard is the binding energy (Eb ═ 285.0eV) of C1S of the polluted carbon.

In the following preparation examples, a clover type alumina strip carrier having a circumscribed circle diameter of 1.4 mm from Changling catalyst division was used as the carrier.

Preparation example 1

(1) Weighing 25.4g of ammonium thiomolybdate, adding deionized water to prepare 110mL of aqueous solution, soaking 100g of carrier by using the aqueous solution for 6h, and then drying at 120 ℃ for 4h in vacuum to obtain Mo/Al₂O₃；

(2) 22.1g of cobalt nitrate and 21.55g of EDTA are weighed, deionized water is added to prepare 80mL of solution, and Mo/Al is impregnated₂O₃6h, then dried in vacuum at 120 ℃ for 4h to obtain the oxidation state CoMo/Al₂O₃；

(3) Para oxidation state CoMo/Al₂O₃Carrying out wet vulcanization, wherein the specific conditions comprise: in the presence of hydrogen, the oxidation state CoMo/Al₂O₃Reacting with cyclohexane containing 5 weight percent of carbon disulfide for 6 hours at 300 ℃ and 2.4MPa, wherein the volume space velocity of hydrogen is 1600 hours^-1And when the volume ratio of hydrogen to oil is 400, cooling the reaction temperature to room temperature to obtain the selective mercaptan removal catalyst S-1.

The component contents of the selective sweetening catalyst S-1 and the results of XPS analysis are shown in Table 1.

Preparation example 2

(1) Weighing sulfur31.8g of ammonium molybdate, adding deionized water to prepare 110mL of aqueous solution, soaking 100g of carrier by the aqueous solution for 6h, and then drying in vacuum at 120 ℃ for 4h to obtain Mo/Al₂O₃；

(2) 22.1g of cobalt nitrate and 14.2g of citric acid are weighed, deionized water is added to prepare 80mL of solution, and Mo/Al is impregnated₂O₃6h, then dried in vacuum at 120 ℃ for 4h to obtain the oxidation state CoMo/Al₂O₃；

(3) Para oxidation state CoMo/Al₂O₃Carrying out wet vulcanization, wherein the specific conditions comprise: in the presence of hydrogen, the oxidation state CoMo/Al₂O₃The catalyst is contacted with straight-run gasoline distillate containing 3 weight percent of carbon disulfide for reaction for 10 hours at 320 ℃ and 3.2MPa, and the volume space velocity of hydrogen is 600 hours^-1And when the volume ratio of hydrogen to oil is 300, and the reaction temperature is reduced to room temperature, the selective mercaptan removal catalyst S-2 is obtained.

The component contents of the selective sweetening catalyst S-2 and the results of XPS analysis are shown in Table 1.

Preparation example 3

(1) Weighing 12.69g of ammonium thiomolybdate, adding deionized water to prepare 110mL of aqueous solution, soaking 100g of carrier by using the aqueous solution for 6h, and then drying at 120 ℃ for 4h in vacuum to obtain Mo/Al₂O₃；

(2) Weighing 15.8g of cobalt nitrate and 6.9g of nitrilotriacetic acid, adding deionized water to prepare 80mL of solution, and soaking Mo/Al₂O₃6h, then dried in vacuum at 120 ℃ for 4h to obtain the oxidation state CoMo/Al₂O₃；

(3) Para oxidation state CoMo/Al₂O₃Carrying out wet vulcanization, wherein the specific conditions comprise: in the presence of hydrogen, the oxidation state CoMo/Al₂O₃The catalyst is contacted with straight-run gasoline distillate containing 2 weight percent of dimethyl disulfide (DMDS) for reaction for 5 hours at the temperature of 350 ℃ and the pressure of 1.6MPa, and the volume space velocity of hydrogen is 300 hours^-1And when the volume ratio of hydrogen to oil is 200, and the reaction temperature is reduced to room temperature, the selective mercaptan removal catalyst S-3 is obtained.

The component contents of the selective sweetening catalyst S-3 and the results of XPS analysis are shown in Table 1.

Preparation example 4

The process described in preparation example 1 was followed except that ammonium thiomolybdate, cobalt nitrate and EDTA were co-formulated as a solution to impregnate the support, specifically:

(1) weighing 25.4g of ammonium thiomolybdate, 22.1g of cobalt nitrate and 21.55g of EDTA21, adding deionized water to prepare 110mL of aqueous solution, soaking 100g of carrier in the aqueous solution for 6 hours, and then drying the carrier in vacuum at 120 ℃ for 4 hours to obtain oxidation state CoMo/Al₂O₃；

(2) Para oxidation state CoMo/Al₂O₃Carrying out wet vulcanization, wherein the specific conditions comprise: in the presence of hydrogen, the oxidation state CoMo/Al₂O₃Reacting with cyclohexane containing 5 weight percent of carbon disulfide for 6 hours at 300 ℃ and 2.4MPa, wherein the volume space velocity of hydrogen is 1600 hours^-1And when the volume ratio of hydrogen to oil is 400, cooling the reaction temperature to room temperature to obtain the selective mercaptan removal catalyst S-4.

The component contents of the selective sweetening catalyst S-4 and the results of XPS analysis are shown in Table 1.

Preparation example 5

The process as described in preparation example 1 was followed except that the vacuum drying in step (1) and step (2) was replaced with drying in air at the same temperature for a certain time so that Mo/Al was dried₂O₃And CoMo/Al₂O₃Respectively dried in vacuum with the Mo/Al in preparation example 1₂O₃And CoMo/Al₂O₃The masses are equal.

The selective mercaptan removal catalyst S-5 is obtained by the method.

The component contents of the selective sweetening catalyst S-5 and the results of XPS analysis are shown in Table 1.

Preparation example 6

The process described in preparation 1 is followed, except that the vulcanization is carried out by dry vulcanization, in particular:

(2) 22.1g of cobalt nitrate and 21.55g of EDTA were weighed out and then separatedPreparing the sub-water into 80mL of solution, and soaking Mo/Al₂O₃6h, then dried in vacuum at 120 ℃ for 4h to obtain the oxidation state CoMo/Al₂O₃；

(3) Para oxidation state CoMo/Al₂O₃Carrying out dry vulcanization, wherein the specific conditions comprise:

by H₂S and H₂Mixed gas (H) of (2)₂S volume content of 1%) as sulfur-containing medium, and CoMo/Al in oxidation state₂O₃And (3) carrying out contact reaction for 6h at the temperature of 300 ℃ and the pressure of 2.4MPa, wherein the volume ratio of the gas agent is 400, and obtaining the selective mercaptan removal catalyst S-6 when the reaction temperature is reduced to room temperature.

The component contents of the selective sweetening catalyst S-6 and the results of XPS analysis are shown in Table 1.

Preparation example 7

According to the method of preparation example 1, except that no organic complexing agent EDTA was added, the selective sweetening catalyst S-7 was obtained, and the contents of the components of the selective sweetening catalyst S-7 and the results of XPS analysis are shown in Table 1.

Preparation example 8

According to the method of preparation example 1, except that ammonium thiomolybdate was replaced with ammonium thiotungstate of the same mass and cobalt nitrate was replaced with nickel nitrate of the same mass, the selective sweetening catalyst S-8 was obtained, and the contents of the components of the selective sweetening catalyst S-8 and the results of XPS analysis are shown in Table 1.

Preparation example 9

According to the method of preparation example 1, except that ammonium thiomolybdate was replaced with ammonium heptamolybdate of the same mass based on the molybdenum element, the selective sweetening catalyst S-9 was obtained, and the contents of the components of the selective sweetening catalyst S-9 and the results of XPS analysis are shown in Table 1.

Preparation example 10

According to the method of preparation example 1 except that the amount of ammonium thiomolybdate added was 25.4g, the amount of cobalt nitrate added was 13.2g, and the amount of EDTA added was 12.8g, the selective sweetening catalyst S-10 was obtained, and the contents of the components of the selective sweetening catalyst S-10 and the results of XPS analysis are shown in Table 1.

TABLE 1 content of Selective Dethiol catalyst Components and XPS analysis results

In the following examples, the selective hydrodesulfurization catalyst was RSDS-31 catalyst from a Long-green catalyst plant.

In the following examples, the gasoline fractions used were model compounds of gasoline, which were a solution of 1-hexene, octane, and 100. mu.g/g of 1-heptanethiol, wherein the volume ratio of 1-hexene to octane was 20: 80.

Example 1

(1) As shown in fig. 1, the gasoline fraction and hydrogen gas are mixed and then enter a selective hydrodesulfurization reactor 1 filled with a selective hydrodesulfurization catalyst to perform a selective hydrodesulfurization reaction under the following reaction conditions: the reaction temperature is 320 ℃, the reaction pressure is 1.6MPa, and the volume space velocity of the gasoline fraction is 5h^-1The volume ratio of hydrogen to oil is 300;

(2) cooling the reaction product obtained in the step (1) to 40 ℃ through a first heat exchanger 5, and then introducing the reaction product into a high-pressure separator 4 for gas-liquid separation to obtain a product containing H₂S、H₂The gas and hydrogenated fraction a of (a);

(3) will contain H₂S、H₂Gas inlet of (2) to remove H₂S reactor 10 for removing H₂S (selectively adsorbing hydrogen sulfide by using zinc oxide) to obtain hydrogen-rich gas, compressing the hydrogen-rich gas by using a compressor 7 and then recycling the hydrogen-rich gas to the step (1) for recycling, allowing the hydrogenation fraction a subjected to pressure reduction by a pressure reduction device to enter a low-pressure separator 9 (the pressure is slightly higher than that of the selective sweetening reactor 2 so that the hydrogenation fraction a smoothly flows into the reactor 2) to further separate out hydrogen sulfide dissolved in the hydrogenation fraction a, heating the hydrogenation fraction a by using a second heat exchanger 6, and then allowing the hydrogenation fraction a to enter the selective sweetening reactor 2 filled with the selective sweetening catalyst S-1 prepared in the preparation example 1 to perform selective sweetening reaction to obtain a reaction product b, wherein the reaction conditions comprise: the reaction temperature is 260 ℃, the reaction pressure is 0.5MPa, and the volume space velocity of the hydrogenation fraction a is 8h^-1；

(4) The temperature of the reaction product b is reduced by a third heat exchanger 8Enters a stripping tower 3 for stripping after the temperature reaches 90 ℃, and H₂S and H₂The product oil flows out of the top of the tower, and the product oil is collected at the bottom of the tower.

Examples 2 to 10

The procedure of example 1 was repeated, except that S-1 was replaced with the selective mercaptan-removing catalysts S-2 to S-10 obtained in preparation examples 2 to 10, respectively.

Examples 11 to 15

The procedure was followed as in example 1 except that the selective mercaptan removal reaction in step (3) was carried out under the conditions shown in Table 2, respectively.

TABLE 2 Selective sweetening reaction conditions

Comparative example 1

The steps (1) and (2) are the same as in example 1;

(3) introducing the hydrogenation fraction a into a stripping tower filled with the selective sweetening catalyst S-1 prepared in preparation example 1, and carrying out selective sweetening reaction under the condition of no hydrogen, wherein the operating pressure of the stripping tower is 0.5MPa, no additional stripping medium is added, the average temperature of a catalyst bed layer below the feeding is 150 ℃, and the volume space velocity of the hydrogenation fraction a is 8h^-1And collecting the produced oil at the bottom of the tower.

Comparative example 2

According to the method of comparative example 1, except that the average temperature of the catalyst bed was 260 ℃, it was found that the quality of the produced oil collected at the bottom of the column was significantly reduced, and most of the gasoline product distilled off from the top of the column with hydrogen sulfide, and the effect of stripping hydrogen sulfide from gasoline was not achieved.

Test examples

In the present test example, the desulfurization activity and selectivity by the method provided by the present invention were evaluated in the following manner and used to illustrate the advantageous effects of the method and apparatus for desulfurization of gasoline according to the present invention.

The oils collected at the bottoms of examples 1 to 15 and comparative examples 1 to 2 were analyzed by a color-by-MASS (GC-MASS) analysis method, and the results are shown in Table 3. Wherein, the olefin saturation rate HYD, the removal rate X of heptamercaptan (for explaining the desulfurization activity), the sulfur concentration Y of hexanethiol and the formation factor S of hexanethiol (for explaining the desulfurization selectivity, the lower the S, the better the desulfurization selectivity) of the reaction are calculated according to the following formula:

HYD ═ 100%

X ═ raw heptanethiol concentration-product heptanethiol concentration)/raw heptanethiol concentration X100%

Y-percent hexanethiol concentration in the product x 0.2712 x 10000

S＝Y/(100-HYD)

TABLE 3

Examples	HYD/％	X/％	Y/(μg/g)	S
					Example 1	33.5	100	12.7	0.19
Comparative example 1	3.42	75	28.1	0.24
					Comparative example 2	38.5	100	25.0	0.26
Example 2	38.7	100	13.5	0.22
					Example 3	19.7	99	14.6	0.18
Example 4	39.6	100	14.2	0.24
					Example 5	35.6	100	16.8	0.26
Example 6	35.2	100	14.1	0.22
					Example 7	31.5	100	18.3	0.27
Example 8	29.3	100	20.2	0.29
					Example 9	31	99	25.9	0.38
Example 10	32.3	98	26.3	0.39
					Example 11	25.5	100	16.9	0.23
Example 12	1.59	100	27.5	0.28
					Example 13	50.1	100	15.4	0.31
Example 14	65.3	100	16.8	0.48
					Example 15	75.8	100	11.4	0.47

The results in tables 1 and 3 show that the device and the method for gasoline desulfurization provided by the present invention can realize more efficient removal of mercaptan, lower olefin saturation rate and smaller mercaptan formation factor S even though the same selective mercaptan removal catalyst is used as the method provided by the prior art, which indicates that the method provided by the present invention has high desulfurization activity and good selectivity. The results of the embodiment 1 and the comparative examples 1 and 2 show that the method overcomes the defects of the prior art that the steam stripping and the selective mercaptan removal are carried out in the same reactor, and the method provided by the invention realizes the effective removal of sulfur in gasoline under the condition of lower olefin saturation under the milder condition. The results of examples 1-3 and examples 4-10 of the present invention show that the desulfurization activity and selectivity can be further improved by using the preferred selective sweetening catalyst of the present invention.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims

1. A method for desulfurizing gasoline, the method comprising:

(3) stripping the reaction product b;

the selective mercaptan removal catalyst comprises a carrier, and an active metal component A and an active metal component B which are loaded on the carrier, wherein the active metal component A is selected from at least one of VIII group metal elements, the active metal component B is selected from at least one of VIB group metal elements, the active metal component A and the active metal component B exist in a sulfide form, the atomic ratio of the active metal component A to the sum of the active metal component A and the active metal component B in the catalyst measured by an X-ray fluorescence spectrum is more than 0.4, the content of II active phases A-B-S in the catalyst measured by an X-ray electron energy spectrum is more than 55%, wherein the content of the II active phases A-B-S refers to the amount of the active metal component A existing in the II active phases A-B-S form and the total amount of the active metal component A measured by the X-ray electron energy spectrum The ratio of (A) to (B);

wherein the conditions of the second contact reaction comprise: the reaction temperature is 200 ℃ and 300 ℃, the reaction pressure is 0.3-0.8MPa, and the volume space velocity of the hydrogenation fraction a is 0.1-10h^-1。

2. The method of claim 1, wherein the conditions of the first contact reaction comprise: the reaction temperature is 200-400 ℃, the reaction pressure is 1-5MPa, and the volume space velocity of the gasoline fraction is 1-10h^-1The volume ratio of hydrogen to oil is 100-1000.

3. The method of claim 1, wherein the separation is a gas-liquid separation, and the separated H-containing gas₂S、H₂By removing H from the gas₂And S, obtaining hydrogen-rich gas, and recycling the hydrogen-rich gas to the step (1).

4. The method of claim 1, wherein the atomic ratio of active metal component a to the sum of active metal component a and active metal component B is from 0.4 to 0.7; the content of the II active phase A-B-S is 55-95%.

5. The method of claim 4, wherein the content of the class II active phase A-B-S is 60-90%.

6. The process according to any one of claims 1 and 4 to 5, wherein the support is present in an amount of from 70 to 97% by weight, based on the total amount of the selective sweetening catalyst; the content of the active metal component A is 1-10 wt% and the content of the active metal component B is 2-20 wt% calculated by oxide.

7. The process according to claim 6, wherein the support is present in an amount of from 79 to 93% by weight, based on the total amount of the selective sweetening catalyst; the content of the active metal component A is 1-6 wt% and the content of the active metal component B is 6-15 wt% calculated by oxide.

8. The method of any one of claims 1, 4-5, and 7, wherein the support is a refractory inorganic oxide; the active metal component A is cobalt and/or nickel element, and the active metal component B is molybdenum and/or tungsten element.

9. The method of claim 8, wherein the active metal component a is cobalt and the active metal component B is molybdenum.

10. The method of claim 6, wherein the support is a refractory inorganic oxide; the active metal component A is cobalt and/or nickel element, and the active metal component B is molybdenum and/or tungsten element.

11. The method of claim 10, wherein the active metal component a is cobalt and the active metal component B is molybdenum.

12. The method of any one of claims 1, 4-5, 7, and 9-11, wherein the second contacting reaction of step (2) is at H₂In the presence of S.

13. The method of claim 6, wherein the second contact reaction of step (2) is in H₂In the presence of S.

14. The method of claim 8, wherein the second contact reaction of step (2) is in H₂In the presence of S.

15. The process of any one of claims 1-5, 7, 9-11, and 13-14, wherein the stripping of reaction product b in step (3) comprises: introducing the reaction product b into a stripping tower, and stripping H from the top of the stripping tower₂S and H₂And distilling the gasoline product from the bottom of the tower.

16. The method of claim 6, wherein the pairing reaction of step (3)The way in which product b is stripped comprises: introducing the reaction product b into a stripping tower, and stripping H from the top of the stripping tower₂S and H₂And distilling the gasoline product from the bottom of the tower.

17. The process of claim 8, wherein the stripping of reaction product b in step (3) comprises: introducing the reaction product b into a stripping tower, and stripping H from the top of the stripping tower₂S and H₂And distilling the gasoline product from the bottom of the tower.

18. The process of claim 12, wherein the stripping of reaction product b in step (3) comprises: introducing the reaction product b into a stripping tower, and stripping H from the top of the stripping tower₂S and H₂And distilling the gasoline product from the bottom of the tower.

19. An apparatus for desulfurizing gasoline, the apparatus comprising:

the selective hydrodesulfurization reactor (1), the high-pressure separator (4), the selective mercaptan removal reactor (2) and the stripping tower (3) are sequentially connected through pipelines;

the high-pressure separator (4) is used for carrying out gas-liquid separation on the material at the outlet of the selective hydrodesulfurization reactor (1), and the liquid enters the selective sweetening reactor (2);

the stripping column (3) is used for stripping H generated in the selective mercaptan removal reactor (2)₂S。

20. An apparatus according to claim 19, wherein the apparatus further comprises a low pressure separator (9), an inlet of the low pressure separator (9) being in communication with the liquid outlet of the high pressure separator (4), an outlet of the low pressure separator (9) being in communication with the inlet of the selective sweetening reactor (2), the low pressure separator (9) being for separating hydrogen sulphide dissolved in the liquid.

21. The apparatus according to claim 19 or 20, wherein the apparatus further comprises a compressor (7), an inlet of the compressor (7) being in communication with the gas outlet of the high-pressure separator (4), an outlet of the compressor (7) being in communication with an inlet of the selective hydrodesulfurization reactor (1).