CN106147839A - A kind of method reducing content of sulfur in gasoline - Google Patents

Abstract

A method for reducing the sulfur content of gasoline. The gasoline raw material is fractionated into light distillate gasoline and heavy distillate gasoline. The light distillate gasoline enters the alkali extraction unit to obtain refined light distillate gasoline. After the heavy distillate gasoline is mixed with hydrogen, it enters the first hydrogenation step by step. The reactor, the second hydrogenation reactor, and the third hydrogenation reactor are respectively contacted with the selective hydrodediene catalyst, the selective hydrodesulfurization catalyst I and the selective hydrodesulfurization catalyst II to react, and the selective hydrogenation Both the hydrodesulfurization catalyst I and the selective hydrodesulfurization catalyst II are subjected to selective regulation and control treatment, and the reaction effluent of the third hydrogenation reactor is separated to obtain hydrogenated heavy distillate gasoline. Mix refined light distillate gasoline and hydrogenated heavy distillate gasoline to obtain ultra-low sulfur gasoline products. The invention can process the catalytic cracking gasoline with high sulfur and high olefins, the sulfur content of the product is less than 10 μg/g, the octane number loss is small, and the gasoline yield is over 99%.

Description

A method for reducing gasoline sulfur content

technical field

The invention relates to a method for refining hydrocarbon oil, in particular to a method for reducing the sulfur content of gasoline and producing ultra-low sulfur gasoline.

Background technique

With the rapid increase of the number of automobiles in our country, the problem of air pollution caused by automobile exhaust emissions is becoming more and more serious. The pollutants emitted by automobile exhaust mainly include SOx and NOx. Such pollutants will not only cause acid rain, but also destroy the ozone layer, and NOx can also cause cancer in the human body, causing great harm to humans and the environment. Sulfur in gasoline can poison automobile exhaust gas purification catalysts, seriously affecting its ability to treat exhaust pollutants. Therefore, countries all over the world have formulated more and more stringent gasoline quality standards to limit the sulfur content in gasoline. The U.S. Environmental Protection Agency requires that the sulfur content of motor gasoline be less than 30 μg/g in 2006. The European Union implemented Euro V vehicle exhaust emission standards in 2009, requiring the sulfur content of gasoline to be less than 10 μg/g. In December 2006, my country promulgated the National II and National III standards for motor gasoline, stipulating that the National-III standard for motor gasoline (S<150μg/g) will be implemented nationwide from the end of 2009, and it will be the first to be implemented in Beijing and other regions in line with European standards. V is equivalent to the Beijing V quality standard (S<10μg/g). The continuous improvement of gasoline quality requirements, especially in terms of sulfur content requirements, is a great challenge to my country's oil refining industry. Commercial gasoline is blended from basic raw materials such as straight-run naphtha, reformed oil, catalytic cracking gasoline, and alkylated gasoline. At present, among the blending components of domestic commercial gasoline, catalytic cracking gasoline is the main source, accounting for about 70-80% of the total gasoline pool (about 30-40% in foreign countries), and the sulfur content of catalytic cracking gasoline is relatively high, accounting for 90% of gasoline products The above sulfur comes from FCC gasoline. It can be seen that reducing the sulfur content of FCC gasoline is the key to producing clean gasoline. Moreover, judging from the existing processing flow of my country's oil refining industry, for a long period of time in the future, the blending components of my country's motor gasoline will still be dominated by catalytic cracked gasoline, and low-sulfur content and high-octane components (reformed gasoline and alkylated gasoline) is difficult to fundamentally change the status quo. Therefore, reducing the sulfur content of FCC gasoline is the key to reducing the sulfur content of finished gasoline.

To reduce the sulfur content of catalytic cracking gasoline, usually, hydroprocessing of catalytic cracking raw materials (pre-hydrogenation), hydrodesulfurization of catalytic cracking gasoline (post-hydrogenation) or a combination of the two methods can be adopted. Among them, the pretreatment of catalytic cracking raw materials can greatly reduce the sulfur content of catalytic cracking gasoline, but it needs to be operated under very harsh conditions of temperature and pressure. At the same time, because of the large processing capacity of the device, the hydrogen consumption is also relatively large, all of which will increase the capacity of the device. investment or operating costs. However, due to the heavy crude oil in the world, more and more catalytic cracking units have begun to process inferior raw materials containing atmospheric and vacuum residues, so the number of hydrogenation units for catalytic cracking raw materials is also increasing year by year. At the same time, with the innovation of catalytic cracking technology and the gradual application of catalytic cracking desulfurization additives, the sulfur content of catalytic cracking gasoline of some enterprises in my country can reach below 500 μg/g, or even below 150 μg/g. But if you want to further reduce the sulfur content of FCC gasoline, make it less than 50μg/g (meet the limit of gasoline sulfur content in Euro IV emission standard), or even less than 10μg/g (meet the limit of sulfur content in gasoline in Euro V emission standard) , then the operating severity of the catalytic cracking raw material hydrogenation unit must be greatly increased, which is very economically uneconomical. An effective way to solve the above problems is to hydrodesulfurize FCC gasoline while minimizing the saturation of olefins in order to minimize the loss of octane number.

FCC gasoline hydrogenation obviously has its unique advantages, which are lower than FCC raw material hydrogenation pretreatment in terms of equipment investment, production cost and hydrogen consumption, and its different desulfurization depths can meet the requirements of different specifications of sulfur content. However, if the traditional hydrodesulfurization method is used, the olefin components with high octane number in catalytic cracking gasoline will be saturated in large quantities, resulting in a large loss of octane number. Therefore, it is necessary to develop a selective hydrodesulfurization technology for FCC gasoline with low investment and low octane loss. The second-generation technology of catalytic cracking gasoline selective hydrodesulfurization (RSDS-II) developed by the Research Institute of Petrochemical Sciences can reduce the sulfur content in catalytic cracking gasoline to below 50 μg/g, and the octane number loss is small. In order to reduce the sulfur content in FCC gasoline to a lower level, such as less than 10μg/g, the reaction severity must be further increased. How to reduce the olefin saturation rate under harsh reaction conditions and reduce the octane loss of the product is a selectivity The key to hydrodesulfurization technology.

CN101381624A discloses that olefin-containing naphtha is passed through two reaction stages, wherein the first stage is filled with a special catalyst to remove most of the sulfur under mild conditions, and the olefin saturation rate is not higher than 30%. Further desulfurization reaction is carried out under the conditions to minimize the formation of mercaptans, and the olefin saturation rate is not higher than 20%, so that the sulfur content of the product is lower than 10 μg/g.

WO 2007/061701 discloses a method for producing low-sulfur gasoline using a two-stage reaction. In this method, a large amount of sulfur-containing compounds are removed in the first reactor, and the effluent of the first reaction is stripped, ammonia washed, etc. The method is to remove H ₂ S, and the product after removing H ₂ S enters the second reactor for further desulfurization reaction, so as to reduce the sulfur content to the lowest level.

WO0179391 describes a method for producing low sulfur catalytically cracked gasoline. In the first step, selective hydrodesulfurization of catalytically cracked gasoline is carried out to obtain intermediate products; in the second step, the intermediate products are subjected to sweetening treatment. The patent mainly involves the removal methods of mercaptan sulfur, mainly including extraction, adsorption fractionation, fixed bed oxidation, alkali extraction, catalytic decomposition, etc.

US5906730 discloses a staged desulfurization process for FCC gasoline. The first stage maintains a desulfurization rate of 60-90%. Process conditions: temperature 200-350°C, pressure 5-30kg/cm ² , liquid hourly space velocity 2-10h ^-1 , hydrogen-oil ratio 89-534v/v, H ₂ S concentration Control <1000ppm. The second stage controls the desulfurization rate to 60-90%. The process conditions are: temperature 200-300°C, pressure 5-15kg/cm ² , liquid hourly space velocity 2-10h ^-1 , hydrogen-oil ratio 178-534v/v, H ₂ S concentration Control <500ppm. If the second-stage desulfurization still fails to achieve the expected purpose, the outlet effluent of the second-stage desulfurization will continue to be desulfurized, and the process conditions are the same as those of the second-stage desulfurization process. However, from the perspective of its implementation effect, when the total desulfurization rate reaches 95%, the olefin saturation rate is 25%. If this technology is used to produce sulfur-free gasoline, the octane number loss of the product will be relatively large.

Under high desulfurization rate, higher reaction temperature is more conducive to olefin hydrogenation saturation reaction, if only by increasing the reaction temperature to further increase the desulfurization rate will lead to a large amount of olefin saturation, and too high reaction temperature will reduce the catalyst operating cycle . If a lower reaction temperature is used, it is beneficial to improve the selectivity of the desulfurization reaction. However, at a lower reaction temperature, the H ₂ S generated by the desulfurization reaction and the olefins in the raw material are more likely to react to form mercaptans. Especially when producing national V gasoline with a sulfur content less than 10 μg/g, the reaction of H ₂ S and olefins to form mercaptans is even close to equilibrium under the conditions of selective hydrogenation process. In some cases, this reaction even leads to the inability to produce National V gasoline with a sulfur content of less than 10 μg/g. There are several theoretical analysis methods to break this reaction balance and move it to the direction of desulfurization: First, a large amount of olefins in the raw material is hydrogenated and saturated, and the concentration of olefins is reduced, and the reaction will move to the direction of desulfurization, but a large amount of olefins is saturated The large octane number loss is exactly what we want to avoid; 2. Remove the H ₂ S generated by the desulfurization reaction. Since H ₂ S is continuously generated during the reaction process, it is difficult to remove the H 2 S under the reaction operating conditions in a fixed bed reactor. To remove H ₂ S directly, a two-stage method must be adopted. The first stage removes a large amount of sulfur, and then a high-pressure gas tower is installed in the middle, and the temperature is lowered for gas-liquid separation to remove H ₂ S, and then enter the second stage for deep desulfurization . However, this method will inevitably cause a lot of energy consumption.

Contents of the invention

The technical problem to be solved by the present invention is how to further reduce the loss of octane number of the product while deeply hydrodesulfurizing the gasoline raw material. gasoline method.

The method provided by the invention comprises the following steps:

(1) Fractional distillation of gasoline raw materials into light distillate gasoline and heavy distillate gasoline, wherein the cut point of light distillate gasoline and heavy distillate gasoline is 45°C to 75°C,

(2) The light distillate gasoline enters the alkali extraction unit, and the mercaptan sulfur therein is removed through alkali washing and refining to obtain the refined light distillate gasoline;

(3) Heavy distillate gasoline and hydrogen enter the first hydrogenation reaction zone together, and react with the selective dedienization catalyst, and the reaction effluent of the first hydrogenation reaction zone directly enters the second hydrogenation reaction zone without separation contact with the selective hydrodesulfurization catalyst I that has undergone catalyst selective regulation and control treatment, and carry out selective hydrodesulfurization reaction, and the reaction effluent in the second hydrogenation reaction zone will all enter the third hydrogenation reaction zone without gas-liquid separation, Contact with the selective hydrodesulfurization catalyst II that has undergone the selective control and control of the catalyst for reaction, the reaction effluent in the third hydrogenation reaction zone is cooled and separated, and the separated liquid phase stream enters the stripping tower, and the bottom of the stripping tower The effluent is hydrogenated heavy distillate gasoline. In the third reaction zone, the reaction is carried out at the final operating temperature of the selective hydrodesulfurization catalyst II. At the same time, the reaction temperature of the second reaction zone is adjusted to compensate for the selective desulfurization loss of activity of hydrodesulfurization catalyst II,

(4) The refined light distillate gasoline obtained in step (2) is mixed with the hydrogenated heavy distillate gasoline obtained in step (3) to obtain a gasoline product.

The distillation range of the gasoline raw material is 30-205°C, the volume fraction of olefins is 5%-60%, and the sulfur content is 50-5000μg/g. The gasoline raw material is selected from any one of catalytic cracking gasoline, catalytic cracking gasoline, coker gasoline, thermal cracking gasoline, and straight-run gasoline or a mixture of several of them, preferably catalytic cracking gasoline.

The reaction conditions of the first hydrogenation reaction zone are: hydrogen partial pressure 1.0-4.0MPa, preferably 1.0-3.0MPa, reaction temperature 80-300°C, preferably 120-270°C, volume space velocity 2-10h ^-1 , Preferably 6-10h ^-1 , hydrogen-oil volume ratio 200-1000Nm ³ /m ³ , preferably 300-800Nm ³ /m ³ .

The reaction conditions of the second hydrogenation reaction zone are: hydrogen partial pressure 1.0-3.0MPa, preferably 1.0-2.0MPa, reaction temperature 200-350°C, preferably 220-300°C, volume space velocity 2.0-8.0h ^-1 , preferably 3.0-6.0h ^-1 , hydrogen-oil volume ratio 200-1000Nm ³ /m ³ ; the reaction conditions in the third hydrogenation reaction zone are: hydrogen partial pressure 1.0-3.0MPa, reaction temperature 340-420°C, Preferably 350-390°C, volume space velocity 10.0-40.0h ^-1 , preferably 12.0-30.0h ^-1 , hydrogen-oil volume ratio 200-1000Nm ³ /m ³ .

In the present invention, the reactant flow is carried out in the second hydrogenation reactor at a lower temperature and a lower space velocity to carry out selective hydrodesulfurization reaction, remove most of the sulfur in the raw material, and reduce the olefin saturation rate as much as possible . The desulfurization rate of the outlet stream of the second reactor is controlled to 60-99%, preferably 80-98%, and the RON loss is not greater than 0.2-2.0, preferably 0.2-1.0).

The material at the outlet of the second hydrogenation reactor does not undergo gas-liquid separation, and all enters the third hydrogenation reactor after heating up. Since most of the sulfur in the raw material is removed in the second hydrogenation reactor, the outlet of the second hydrogenation reactor The sulfur content in the liquid phase of the material is already very low, but the H ₂ S concentration in the gas phase is relatively high. In order to avoid mercaptans from reacting with olefins in the third hydrogenation reactor, the present invention maintains the operating conditions of the third reactor reaction at the final operating temperature of the catalyst. The catalyst terminal operating temperature refers to the highest service temperature at which the catalyst has catalytic activity. At the same time, the third hydrogenation reactor adopts the selective hydrodesulfurization catalyst II with better selectivity but relatively low activity, and then through the selective control treatment step, the reactant flows in the third hydrogenation reactor , can carry out further desulfurization reaction at high temperature, and effectively avoid the formation of mercaptans, so that heavy distillate gasoline with a sulfur content of less than 10 μg/g can be obtained. The present invention compensates for the activity loss of the selective hydrodesulfurization catalyst II by adjusting the reaction temperature of the second hydrogenation reactor.

Preferably, the reaction temperature in the second hydrogenation reaction zone is 60-150° C. lower than the reaction temperature in the third hydrogenation reaction zone.

Preferably, the volume space velocity of the second hydrogenation reaction zone is 2-38h ^-1 higher than the volume space velocity of the third hydrogenation reaction zone.

The selective hydrodedienization catalyst is a Group VIB metal and/or a Group VIII metal catalyst supported on an alumina carrier and/or a silica-alumina carrier, wherein the Group VIB metal is selected from molybdenum and/or tungsten , the Group VIII metal is selected from cobalt and/or nickel.

The selective hydrodesulfurization catalyst I is a catalyst containing Group VIII non-noble metal components and Group VIB metal components and one or more organic substances selected from alcohols, organic acids and organic amines supported on an alumina carrier, wherein the group VIII non-noble metal is selected from cobalt and/or nickel, and the group VIB metal is selected from molybdenum and/or tungsten.

Preferably, the selective hydrodesulfurization catalyst I is calculated as an oxide and based on the catalyst, the mass fraction of the metal component of Group VIII is 0.1-6%, and the mass fraction of the metal component of Group VIB is 1-6%. 25%, the molar ratio of the organic matter to the Group VIII metal component is 0.5-2.5, the carrier is a kind of bimodal porous alumina, characterized by mercury porosimetry, and the pore volume of the carrier is 0.9-1.2 ml /g, the specific surface area is 50-300 ^m2 /g, the pore volume of pores with a diameter of 10-30nm accounts for 55-80% of the total pore volume, and the pore volume of pores with a diameter of 300-500nm accounts for 10-35% of the total pore volume %.

The selective hydrodesulfurization catalyst II is supported on a silica carrier and contains Group VIII non-noble metal components and Group VIB metal components and one or more organic substances selected from alcohols, organic acids and organic amines The catalyst wherein the Group VIII non-noble metal is selected from cobalt and/or nickel, and the Group VIB metal is selected from molybdenum and/or tungsten.

Preferably, the selective hydrodesulfurization catalyst II is calculated as an oxide and based on the catalyst, the mass fraction of the Group VIII metal component is 0.1-3%, and the mass fraction of the Group VIB metal component is 1% ~15%, the molar ratio of the organic matter to the Group VIII metal component is 0.5~2.5, the carrier is a kind of silicon oxide, the pore volume is 0.5~1.0 ml/g, and the specific surface area is 20~200 ^m2 / gram.

The preferred preparation methods of selective hydrodesulfurization catalyst I and selective hydrodesulfurization catalyst II are as follows.

In the present invention, the introduction of at least one metal component selected from non-noble metals of Group VIII and at least one metal component selected from Group VIB on the carrier and one or more selected from alcohols, organic acids and organic amines Several methods of organic matter are preferably impregnation methods, and the impregnation methods are conventional methods, such as pore saturation impregnation, excess liquid impregnation, and spray impregnation. Wherein, the group VIII, group VIB and one or more organic substances selected from alcohols, organic acids and organic amines can be introduced individually, or two or three can be introduced simultaneously. When introducing by impregnation, it includes preparing the impregnation solution, for example, from the compound containing at least one metal component selected from Group VIB, the compound containing at least one metal component from Group VIII or selected from alcohols One or more organic substances in organic acids and organic amines are respectively prepared impregnating solutions, and these impregnating solutions are used to impregnate the supports respectively; The compound of the metal component of Group VIII and two or three kinds of organic substances selected from one or more of alcohols, organic acids and organic amines prepare mixed impregnating solutions, and use these impregnating solutions to impregnate the carrier separately. When the impregnation is a stepwise impregnation, there is no limitation on the order in which the impregnation solution impregnates the support. Although not required, a drying step is preferably included after each impregnation. The drying conditions include: a drying temperature of 100-210° C., preferably 120-190° C., and a drying time of 1-6 hours, preferably 2-4 hours.

The activity of the catalyst is measured by the reaction temperature at which the same desulfurization rate is achieved. The activity of the selective hydrodesulfurization catalyst I is 5°C-60°C higher than that of the selective hydrodesulfurization catalyst II.

The selectivity of the catalyst is measured by the selectivity factor. The selectivity factor adopts the following definition: S ₌ log(Sp/ _Sf )/log( _Op / _Of ). In the formula: S—selectivity factor; S _p —sulfur content of product; S _f —sulfur content of raw material; O _p —mass content of olefin in product; O _f —mass content of olefin in raw material. The selectivity of the selective hydrodesulfurization catalyst II is 2-10 units higher than that of the selective hydrodesulfurization catalyst I.

Both the selective hydrodesulfurization catalyst I and the selective hydrodesulfurization catalyst II are subjected to catalyst selectivity control treatment after the sulfidation is completed, so as to meet the corresponding activity and selectivity requirements. After the selective hydrodesulfurization catalyst is sulfided, there are two kinds of active centers, the desulfurization active center and the olefin hydrogenation active center. The invention adds a catalyst selectivity control process between the sulfidation process and the normal production process, which can obviously shield one of the active centers, thereby improving the selectivity of the selective hydrogenation desulfurization catalyst. The catalyst selectivity control process is to contact the activating raw material with the selective hydrogenation desulfurization catalyst in the atmosphere of activating gas and under the condition of catalyzing reaction. This process can effectively make the coke cover on the catalyst olefin hydrogenation saturation active center, so that the selective hydrodesulfurization catalyst olefin hydrogenation saturation activity is greatly reduced, while the desulfurization active center is effectively protected, so that the desulfurization activity of the selective hydrodesulfurization catalyst Little or no loss.

The catalyst selectivity control treatment of the selective hydrodesulfurization catalyst I and the selective hydrodesulfurization catalyst II includes the following steps:

(a) After the vulcanization process is over, adjust the gas in the reaction system to be the catalyst gas;

(b) introducing the catalyst raw material into the reaction system, and contacting the catalyst with the catalyst for 24 to 96 hours under the conditions of the catalyst reaction;

(c) After the catalyzing reaction is finished, adjust the process conditions to normal reaction conditions, and switch the reaction feed to full distillate gasoline or heavy distillate gasoline;

(d) Adjusting the gas in the reaction system to be a hydrogen-rich gas for normal reaction.

The catalytic gas includes hydrogen, hydrogen sulfide and carbon monoxide, based on the whole catalytic gas, wherein the volume fraction of hydrogen is not less than 70%, and the sum of the volume fractions of hydrogen sulfide and carbon monoxide is 0.05% to 5%; preferably, hydrogen The volume fraction of hydrogen sulfide and carbon monoxide is not less than 80%, and the sum of the volume fractions of hydrogen sulfide and carbon monoxide is 0.3% to 2%.

The catalytic activation reaction conditions are: hydrogen partial pressure 0.6-2.0MPa, reaction temperature 200-350°C, volume space velocity 1-10h ^-1 , hydrogen-oil volume ratio 50-400Nm ³ /m ³ . Preferably, the catalyst raw material is contacted with the catalyst for 48-80 hours under the conditions of the catalyst reaction.

In a preferred embodiment, the reaction temperature of the catalytic activation reaction is 30-100° C. higher than that of the normal reaction.

In a preferred embodiment, the volume space velocity of the catalytic activation reaction is 2-4 h ^-1 lower than that of the normal reaction.

The distillation range of the catalyst raw material is 30-350°C, wherein the volume fraction of olefins is 5%-60%.

Preferably, the catalyst raw material also contains aromatic hydrocarbons, and the volume fraction of aromatic hydrocarbons is 5%-60%.

In the step (d) hydrogen-rich gas, based on the whole hydrogen-rich gas, the volume fraction of hydrogen is at least 70%, and the sum of the volume fractions of hydrogen sulfide and carbon monoxide is less than 0.05%. Preferably the volume fraction of hydrogen is at least 80%, and the sum of the volume fractions of hydrogen sulfide and carbon monoxide is less than 0.02%.

In a preferred embodiment of the present invention, in step (b), first reduce the concentration of hydrogen sulfide gas in the reactor gas, then increase the concentration of carbon monoxide gas in the reactor gas, and finally adjust the gas in the reactor to catalyze gas.

In a preferred embodiment of the present invention, in step (d), first reduce the concentration of carbon monoxide gas in the reactor gas, then reduce the concentration of hydrogen sulfide gas in the reactor gas, and finally adjust the gas in the reactor to be hydrogen-rich gas.

By adopting the method provided by the invention, the catalytic cracking gasoline with high sulfur and high olefins can be processed, the sulfur content of the product is less than 10 μg/g, the loss of octane number is small, and the gasoline yield is over 99%. Compared with the prior art, while further reducing the sulfur content, the octane number loss of the product is kept small. At the same time, the activity loss of the catalyst in the third reactor is compensated by the second reactor, which maintains the service life of the catalyst, maximizes the selectivity of the reaction and prolongs the operating period of the device.

Description of drawings

The accompanying drawing is a schematic flow chart of the method for reducing the sulfur content of gasoline provided by the present invention.

detailed description

The method provided by the present invention will be further described below in conjunction with the accompanying drawings, but the present invention is not limited thereby.

As shown in the accompanying drawings, the method for reducing the sulfur content of gasoline provided by the present invention is described in detail as follows: the whole-fraction gasoline raw material from pipeline 1 enters fractionation tower 2, and the light-fraction gasoline obtained after splitting enters alkali extraction sweetening through pipeline 3 Unit 4 performs sweetening treatment, and the light fraction gasoline after sweetening is mixed with the stream from pipeline 34 through pipeline 5 to obtain full distillate products. The heavy distillate gasoline obtained from the fractionating tower 2 flows out from the pipeline 6, is boosted by the raw material pump 7, mixes with the hydrogen from the pipeline 31, enters the heat exchanger 8, exchanges heat with the material from the pipeline 22, and enters the first gas through the pipeline 9. The hydrogenation reactor 10 is for selective dealdiene reaction. The effluent from the first hydrogenation reactor enters the heating furnace 12 through the pipeline 11 to be heated, and then enters the second hydrogenation reactor 14 through the pipeline 13 for selective hydrodesulfurization reaction. The effluent of the second hydrogenation reactor passes through the pipeline 15 and the material from the pipeline 21 is exchanged through the heat exchanger 16, and then enters the heating furnace 18 through the pipeline 17 to be heated, and then enters the third hydrogenation reactor 20 through the pipeline 19, and the third The reactor effluent enters the heat exchanger 16 through the pipeline 21 to exchange heat with the material from the pipeline 15, then enters the heat exchanger 8 through the pipeline 22, and enters the heat exchanger 8 through the pipeline 7 after heat exchange with the material from the pipeline 7, and enters through the air cooling 24 and water cooling 25 through the pipeline 23 After cooling, it enters the high-pressure separator 26. After the gas-liquid separation in the high-pressure separator 26, the hydrogen-rich gas at the top enters the desulfurization tower 28 through the pipeline 27 to remove H2S in the _hydrogen gas, and then enters the circulating _hydrogen compressor 30 through the pipeline 29 to boost the pressure. Mix with the material at the outlet of the raw material pump 7 through the pipeline 31. The stream obtained from the bottom of the high-pressure separator 26 enters the stabilizing tower 33 through the pipeline 32, and the light hydrocarbon gas at the top of the tower is extracted from the pipeline 35, and the bottom product is mixed with the stream from the pipeline 5 through the pipeline 34 to obtain a full fraction gasoline product.

The following examples will further illustrate the method provided by the present invention, but do not limit the present invention thereby.

The trade names of the hydrotreating catalysts C, D, and E used in the comparative example are RGO-3, RSDS-21, and RSDS-22, respectively, produced by Sinopec Catalyst Changling Branch.

The trade name of the selective hydrodedienization catalyst used in the examples is RGO-3, produced by Sinopec Catalyst Changling Branch.

The selective hydrodesulfurization catalyst I used in the examples is catalyst A, and the selective hydrodesulfurization catalyst II is catalyst B. The carrier of catalyst A is alumina, and the active metal composition is: 13.5% by weight of molybdenum oxide and 4.0% by weight of cobalt oxide. The carrier of catalyst B is silicon oxide, and the active metal composition is: 8.5% by weight of molybdenum oxide and 3.0% by weight of cobalt oxide.

The catalyst activity is measured by the reaction temperature at which the same desulfurization rate is achieved. The activity of catalyst A is 5-60°C higher than that of catalyst B.

The selectivity of the catalyst is measured by the selectivity factor, and the selectivity of catalyst A is 2-10 units higher than that of catalyst B.

The selectivity factor adopts the following definition: S ₌ log(Sp/ _Sf )/log( _Op / _Of ). In the formula: S—selectivity factor; S _p —sulfur content of product; S _f —sulfur content of raw material; O _p —mass content of olefin in product; O _f —mass content of olefin in raw material.

In order to give full play to the hydrodesulfurization performance of the catalyst, the above-mentioned catalysts need to be pre-sulfurized before contacting the formal raw materials. In the comparative examples and examples listed below, the presulfurization method of each catalyst is the same.

In the embodiment, both catalyst A and catalyst B have been subjected to selective regulation and control treatment. The process is as follows: after the sulfidation is completed, the gas in the reaction system is adjusted to be a catalytic gas. In the catalytic gas, the volume fraction of hydrogen is 90%. The sum of the volume fractions of hydrogen sulfide and carbon monoxide is 1.8%. The catalytic raw materials are introduced into the reaction system, and the catalytic conditions are hydrogen partial pressure 1.6MPa, hydrogen-oil ratio 100Nm ³ /m ³ , volumetric space velocity 4.0h ^-1 , Under the condition of a reaction temperature of 350° C., the catalytic raw material was contacted with the catalyst for 72 hours, and the catalyst was selectively controlled. The distillation range of the catalytic raw material is 30-350°C, wherein the volume fraction of olefins is 28%, and the volume fraction of aromatics is 20%. After the selective regulation and control treatment of the catalyst is completed, adjust to normal reaction conditions, switch the reaction feed to the heavy fraction of raw oil, and switch the gas in the reactor to hydrogen-rich gas. Based on the overall hydrogen-rich gas, the volume fraction of hydrogen is 90%, the sum of the volume fractions of hydrogen sulfide and carbon monoxide is 0.005%.

Comparative example 1

A catalytic cracking gasoline feedstock F (see Table 1 for the feedstock properties) is first cut into light distillate gasoline (distillation range C ₅ ~ 65°C) and heavy distillate gasoline (distillation range 65°C ~ 190°C) in a fractionating tower . Wherein the mass proportion of light distillate gasoline is 25%, and the mass proportion of heavy distillate gasoline is 75%. Light distillate gasoline is sweetened by alkali extraction; heavy distillate gasoline is hydrodesulfurized by a selective hydrodesulfurization method with two reactors, the first reactor is filled with catalyst C, and the second reactor is filled with catalyst D and E, the filling volume ratio of the two is D:E=85:15. The light distillate gasoline after alkali extraction is mixed with the heavy distillate gasoline after hydrodesulfurization to obtain the whole distillate gasoline product. The product properties and reaction process conditions are shown in Table 2. It can be seen from Table 2 that the sulfur content of the product is 8 μg/g, the olefin volume saturation rate is 43.8%, the RON loss is 3.2, and the product mass yield is 99.8%.

Comparative example 2

A catalytically cracked gasoline feedstock F is first cut into light distillate gasoline (distillation range C ₅ ~65°C) and heavy distillate gasoline (distillation range 65°C~190°C) in a fractionating tower. Wherein the mass proportion of light distillate gasoline is 25%, and the mass proportion of heavy distillate gasoline is 75%. Alkaline extraction sweetening of light distillate gasoline; heavy distillate gasoline adopts three reactors for zoned reaction. The first reactor was filled with catalyst C, and both the second and third reactors were filled with catalyst E. The specific reaction conditions and the properties of the whole distillate gasoline product are shown in Table 2. As can be seen from Table 2, the sulfur content of the product is 8 μg/g, the olefin saturation rate is 31.5%, the RON loss is 1.6, and the product yield is 99.7 wt. %.

However, due to the low activity of catalyst E, the second reactor adopted a higher reaction temperature to maintain the desulfurization activity. After 3000 hours of operation, the activity of catalyst E dropped significantly, and continued to increase the reaction temperature to maintain the activity of catalyst E. The operating temperature of the second hydrogenation reactor is raised from 310 to 320. Due to the limited space for raising the temperature, it will soon reach the final operating temperature of the catalyst, so the operation period of the whole device is short.

Example 1

A catalytically cracked gasoline is used as feedstock F, and its feedstock properties are shown in Table 1. The raw material oil F is first cut into light distillate gasoline (distillation range C ₅ ~65°C) and heavy distillate gasoline (distillation range 65°C~190°C) in the fractionating tower. Wherein the mass proportion of light distillate gasoline is 25%, and the mass proportion of heavy distillate gasoline is 75%. The light distillate gasoline is sweetened by alkali extraction; the heavy distillate gasoline is subjected to hydrodesulfurization treatment using the technological process in the accompanying drawings of the present invention. The light distillate gasoline after alkali extraction is mixed with the heavy distillate gasoline after hydrodesulfurization to obtain the whole distillate gasoline product.

The specific reaction conditions of the first reactor, the second reactor and the third reactor and the properties of the whole fraction gasoline product are shown in Table 3. It can be seen from Table 3 that the sulfur content of the product is 9 μg/g, and the olefin content is 30.6 volume %, RON only lost 1.5, and the product yield was 99.8% by weight.

In the present invention, the operating condition of the reaction in the third reactor is maintained at the operating temperature of the catalyst at the end stage, and the activity loss of the selective hydrodesulfurization catalyst II is compensated by adjusting the reaction temperature of the second hydrogenation reactor. Due to the higher catalyst A of the second reactor loading activity, the same, after running for 3000 hours, the operating temperature of the second hydrogenation reactor of the present invention needs to be raised to 270 temperature by 260 temperature, but, because the second hydrogenation reaction of the present invention The temperature raising space of the device is large, so the operation period of the whole device is long.

Example 2

A catalytically cracked gasoline is used as feedstock G, and its feedstock properties are shown in Table 1. The raw material oil G is first cut into light distillate gasoline (distillation range C ₅ ~58°C) and heavy distillate gasoline (distillation range 58°C~205°C) in the fractionating tower. Among them, the proportion of light distillate gasoline is 25% by weight, and the proportion of heavy distillate gasoline is 75% by weight. The light distillate gasoline is sweetened by alkali extraction; the heavy distillate gasoline is subjected to hydrodesulfurization treatment using the technological process in the accompanying drawings of the present invention. The light distillate gasoline after alkali extraction is mixed with the heavy distillate gasoline after hydrodesulfurization in the product tank to obtain the whole distillate gasoline product.

The specific reaction conditions of the first reactor, the second reactor and the third reactor and the properties of the whole fraction gasoline product are shown in Table 3. It can be seen from Table 3 that the sulfur content of the product is 8 μg/g, and the olefin content is 24.1 volume %, RON only lost 1.1, and the product yield was 99.7% by weight.

Example 3

A catalytically cracked gasoline is used as feedstock I, and its feedstock properties are shown in Table 1. Raw oil I is first cut into light distillate gasoline (distillation range C ₅ ~60°C) and heavy distillate gasoline (distillation range 60°C~205°C) in the fractionating tower. Among them, the proportion of light distillate gasoline is 24% by weight, and the proportion of heavy distillate gasoline is 76% by weight. The light distillate gasoline is sweetened by alkali extraction; the heavy distillate gasoline is subjected to hydrodesulfurization treatment using the technological process in the accompanying drawings of the present invention. The light distillate gasoline after alkali extraction is mixed with the heavy distillate gasoline after hydrodesulfurization in the product tank to obtain the whole distillate gasoline product.

The specific reaction conditions of the first reactor, the second reactor and the third reactor and the properties of the whole fraction gasoline product are shown in Table 3. It can be seen from Table 3 that the sulfur content of the product is 8 μg/g, and the olefin content is 22.6 volume %, RON only lost 1.0, and the product yield was 99.6% by weight.

Table 1

raw material name f G I Density (20℃), g/ ^cm3 0.7234 0.7321 0.7311 Sulfur, μg/g 1096 631 600 Olefin content, volume % 39.7 28.8 26.9 Distillation range (ASTM D-86), ℃ initial boiling point 26 37 31 10% 40 52 44 50% 85 96 82 end point 190 200 200 RON 94.4 90.8 94.2 MON 81.6 80.7 82.2 Antiknock index 88.0 85.8 88.2

Table 2

Comparative example 1 Comparative example 2 Raw oil f f Reaction conditions first reactor catalyst C C Reaction temperature, °C 180 180 Hydrogen partial pressure, MPa 1.6 1.6 Hydrogen oil volume ratio, Nm ³ /m ³ 400 400 Volumetric space velocity, h ^-1 8.0 8.0 second reactor catalyst D+E E. Reaction temperature, °C 310 310 Hydrogen partial pressure, MPa 1.6 1.6 Hydrogen oil volume ratio, Nm ³ /m ³ 400 400 Volumetric space velocity, h ^-1 4.0 4.0

third reactor none catalyst - E. Reaction temperature, °C - 360 Hydrogen partial pressure, MPa - 1.6 Hydrogen oil volume ratio, Nm ³ /m ³ - 400 Volumetric space velocity, h ^-1 - 12 product nature Density (20℃), g/ ^cm3 0.721 0.720 S, μg/g 8 8 Olefin content, volume % 22.3 27.2 RON 91.2 92.8 MON 80.8 81.0 Volume Olefin Saturation, % 43.8 31.5 Mass desulfurization rate, % 99.3 99.3 RON loss 3.2 1.6 Riot Index Loss 2.0 1.1

table 3

Example 1 Example 2 Example 3 Raw oil f G I Reaction conditions First Hydrotreating Reactor catalyst C C C Reaction temperature, °C 180 180 180 Hydrogen partial pressure, MPa 1.6 1.6 1.6 Hydrogen oil volume ratio, Nm ³ /m ³ 400 400 500 Volumetric space velocity, h ^-1 4.0 4.0 4.0 Second Hydrotreating Reactor catalyst A A A Reaction temperature, °C 260 260 270 Hydrogen partial pressure, MPa 1.6 1.6 1.6 Hydrogen oil volume ratio, Nm ³ /m ³ 400 400 400

Volumetric space velocity, h ^-1 4.0 4.0 4.0 The third hydrotreating reactor catalyst B B B Reaction temperature, °C 360 380 390 Hydrogen partial pressure, MPa 1.6 1.6 1.6 Hydrogen oil volume ratio, Nm ³ /m ³ 400 400 400 Volumetric space velocity, h ^-1 12 20 30 product nature Density (20℃), g/ ^cm3 0.7210 0.7250 0.7230 S, μg/g 8 8 8 Olefin content, volume % 32.6 24.5 23.5 RON 92.9 89.8 93.4 MON 81.3 80.5 82.0 Desulfurization rate, wt% 99.3 98.7 98.7 Olefin saturation rate, volume % 17.8 14.9 12.6 RON loss 1.5 1.0 0.8 Loss of antiknock index 0.9 0.6 0.5 Product quality yield, % 99.8 99.7 99.6

Claims (21)

1. the method reducing content of sulfur in gasoline, comprises the steps:

(1) gasoline stocks is fractionated into light fraction gasoline and heavy distillat gasoline, wherein light fraction gasoline and weight The cut point of distillation gasoline is 45 DEG C～75 DEG C；

(2) light fraction gasoline enters alkali density unit, through alkali cleaning refined removing mercaptan sulfur therein, To refined light fraction gasoline；

(3) heavy distillat gasoline is together with hydrogen, enters the first hydroconversion reaction zone, takes off diene with selectivity Catalyst contact is reacted, and the reaction effluent of the first hydroconversion reaction zone is directly entered the without isolation Two hydroconversion reaction zones and the catalyst for selectively hydrodesulfurizing I that have passed through catalyst choice regulation and control process Contact, carries out selective hydrodesulfurization reaction, and the reaction effluent of the second hydroconversion reaction zone is without gas-liquid Separation fully enters the 3rd hydroconversion reaction zone, with the selectivity that have passed through catalyst choice regulation and control process Hydrobon catalyst II contact is reacted, the reaction effluent of the 3rd hydroconversion reaction zone carries out cooling down, Separating, isolated liquid phase stream enters stripper, and stripping tower bottom effluent is hydrogenation heavy distillat gasoline, In described 3rd reaction zone, carry out anti-at a temperature of operating the latter stage of catalyst for selectively hydrodesulfurizing II Should, meanwhile, by adjusting the reaction temperature of second reaction zone, compensate selective hydrodesulfurization catalysis The loss of activity of agent II,

(4) the refined light fraction gasoline of step (2) gained and the hydrogenation heavy distillat of step (3) gained Gasoline mixes, and obtains gasoline products.

Method the most in accordance with claim, it is characterised in that the boiling range of described gasoline stocks is 30-205 DEG C, the volume fraction of alkene is 5%-60%, and sulfur content is 50-5000 μ g/g.

The most in accordance with the method for claim 1, it is characterised in that the first described hydroconversion reaction zone Reaction condition be: hydrogen dividing potential drop 1.0～4.0MPa, reaction temperature 80～300 DEG C, volume space velocity 2～ 10h^-1, hydrogen to oil volume ratio 200～1000Nm³/m³。

The most in accordance with the method for claim 1, it is characterised in that the second described hydroconversion reaction zone Reaction condition be: hydrogen dividing potential drop 1.0～3.0MPa, reaction temperature 200～350 DEG C, volume space velocity 2.0～ 8.0h^-1, hydrogen to oil volume ratio 200～1000Nm³/m³；The reaction article of the 3rd described hydroconversion reaction zone Part is: hydrogen dividing potential drop 1.0～3.0MPa, reaction temperature 340～420 DEG C, volume space velocity 10.0～40.0h^-1、 Hydrogen to oil volume ratio 200～1000Nm³/m³。

5. according to the method described in claim 1 or 4, it is characterised in that the second described hydrogenation is anti- Answer district's reaction temperature lower than the 3rd hydroconversion reaction zone reaction temperature 60～150 DEG C.

6. according to the method described in claim 1 or 4, it is characterised in that the second described hydrogenation is anti- Answer district's volume space velocity than the 3rd hydroconversion reaction zone volume space velocity low 2～38h^-1。

The most in accordance with the method for claim 1, it is characterised in that described selective hydrodesulfurization is urged The selective regulation of agent I and catalyst for selectively hydrodesulfurizing II processes and comprises the steps:

A () sulfidation terminates after, in adjustment response system, gas is for urging lively atmosphere body；

B () will urge raw material alive to introduce response system, and contact with catalyst under urging reaction condition alive 24～96 hours；

C () urges reaction alive to terminate after, adjusting process condition is normal reaction conditions, switches reaction feed For full distillation gasoline or heavy distillat gasoline；

D () adjusts gas in response system is hydrogen-rich gas, carries out normal reaction.

The most in accordance with the method for claim 7, it is characterised in that described in urge lively atmosphere body include hydrogen, Hydrogen sulfide and carbon monoxide, to urge lively atmosphere body generally benchmark, wherein the volume fraction of hydrogen is not less than 70%, the volume fraction sum of hydrogen sulfide and carbon monoxide is 0.05%～5%.

The most in accordance with the method for claim 8, it is characterised in that described in urge in lively atmosphere body, to urge work Gas generally benchmark, wherein the volume fraction of hydrogen is not less than 80%, hydrogen sulfide and carbon monoxide Volume fraction sum is 0.3%～2%.

The most in accordance with the method for claim 7, it is characterised in that urge the reaction condition alive to be: hydrogen divides Pressure 0.6～2.0MPa, reaction temperature 200～350 DEG C, volume space velocity 1～10h^-1, hydrogen to oil volume ratio 50～400Nm³/m³。

11. in accordance with the method for claim 7, it is characterised in that urges raw material alive urging reaction bar of living Contact with catalyst 48～80 hours under part.

12. in accordance with the method for claim 7, it is characterised in that the described boiling range urging raw material alive Being 30～350 DEG C, wherein, the volume fraction of alkene is 5%～60%.

13. in accordance with the method for claim 12, it is characterised in that described urging in raw material alive also contains Having aromatic hydrocarbons, the volume fraction of aromatic hydrocarbons is 5%～60%.

14. in accordance with the method for claim 7, it is characterised in that the hydrogen rich gas of described step (d) Body, with hydrogen-rich gas generally benchmark, the volume fraction of hydrogen is at least 70%, hydrogen sulfide and an oxygen Change the volume fraction sum of carbon less than 0.05%.

15. in accordance with the method for claim 1, it is characterised in that described selective hydrogenation takes off Diene catalyst be supported on the vib metals in alumina support and/or silica-alumina supports and/or Group VIII metallic catalyst, wherein vib metals is selected from molybdenum and/or tungsten, group VIII gold Belong to selected from cobalt and/or nickel.

16. in accordance with the method for claim 1, it is characterised in that described selective hydrodesulfurization Catalyst I be load on the alumina support containing group VIII non-noble metal components and vib Metal component and in alcohol, organic acid and organic amine one or more organic catalyst, its Middle group VIII base metal is selected from cobalt and/or nickel, and vib metals is selected from molybdenum and/or tungsten.

17. in accordance with the method for claim 16, it is characterised in that described selective hydrodesulfurization is urged Agent I, counts and on the basis of catalyst by oxide, and the quality of described group VIII metal component is divided Number is 0.1～6%, and the mass fraction of vib metals component is 1～25%, described Organic substance with The mol ratio of group VIII metal component is 0.5～2.5, and described carrier is a kind of bimodal porous aluminum oxide, Characterizing with mercury injection method, the pore volume of described carrier is 0.9～1.2 ml/g, and specific surface area is 50～300 Rice²/ gram, a diameter of 10～the pore volume in 30nm hole account for total pore volume 55～80%, a diameter of 300～ The pore volume in 500nm hole accounts for the 10～35% of total pore volume.

18. in accordance with the method for claim 1, it is characterised in that described selective hydrodesulfurization Catalyst II be supported on silica support containing group VIII non-noble metal components and VIB Race's metal component and in alcohol, organic acid and organic amine one or more organic catalyst, Wherein group VIII base metal is selected from cobalt and/or nickel, and vib metals is selected from molybdenum and/or tungsten.

19. in accordance with the method for claim 18, it is characterised in that described selective hydrodesulfurization is urged Agent II, counts and on the basis of catalyst by oxide, and the quality of described group VIII metal component is divided Number is 0.1～3%, and the mass fraction of vib metals component is 1～15%, described Organic substance with The mol ratio of group VIII metal component is 0.5～2.5, and described carrier is a kind of silicon oxide, and pore volume is 0.5～1.0 ml/g, specific surface area is 20～200 meters²/ gram.

20. according to described method arbitrary in claim 1,16,17,18,19, and its feature exists In, to reach the reaction temperature of identical desulfurization degree to weigh the activity of catalyst, selective hydrodesulfurization The activity of the specific activity catalyst for selectively hydrodesulfurizing II of catalyst I is high 5 DEG C～60 DEG C.

21. according to described method arbitrary in claim 1,16,17,18,19, and its feature exists In, weigh selectivity of catalyst, the selection of catalyst for selectively hydrodesulfurizing II with selectivity factor The property high 2～10 units of selectivity than catalyst for selectively hydrodesulfurizing I.