CN102851068A - Gasoline desulfurization method - Google Patents

Abstract

The invention provides a method for gasoline desulfurization, wherein, the method comprises cutting and fractionating gasoline to obtain a heavy fraction with a relatively high boiling range and a light fraction with a relatively low boiling range; under selective hydrodesulfurization conditions, the heavy fraction and The hydrogen is contacted with the hydrodesulfurization catalyst for selective hydrodesulfurization to obtain the desulfurized heavy fraction; the light fraction is contacted with the lye to desulfurize the light fraction to obtain the lye that has absorbed the sulfide and the desulfurized light fraction; the absorption The lye containing sulfide and the oxidant are contacted with the oxidation catalyst to regenerate the lye to obtain the regenerated lye; the regenerated lye is contacted with a part of the desulfurized heavy fraction to desulfurize the lye, and then phase separation is carried out to obtain The heavy disulfide-absorbed fraction and the desulfurized lye; returning at least a part of the disulfide-absorbed heavy fraction to the cut fractionated heavy fraction and performing the selective hydrodesulfurization. Adopting the method of the invention can obtain higher desulfurization rate and lower octane number loss.

Description

A method for gasoline desulfurization

technical field

The invention relates to a method for gasoline desulfurization.

Background technique

As we all know, the emission of toxic and harmful substances in automobile exhaust seriously affects the air quality. For this reason, countries all over the world have imposed stricter and stricter standards on the quality of oil used as engine fuel. On April 27, 2005, the State Environmental Protection Administration announced the emission standards of China's light-duty vehicles III and IV. Among them, No. Ⅲ emission standard for light vehicles came into effect on July 1, 2007, and No. Ⅳ emission standard came into effect on July 1, 2010. National No. Ⅲ and No. Ⅳ emission standards respectively stipulate that the sulfur content in motor gasoline shall not exceed 150 μg/g and 50 μg/g. It is expected that the national V emission standard will stipulate that the sulfur content in motor gasoline shall not exceed 10 μg/g.

As we all know, the sulfur in gasoline mainly comes from catalytic cracking (FCC) gasoline. As the raw material processed by FCC develops towards heavy quality, the sulfur content of FCC gasoline will further increase. Therefore, reducing the sulfur content of FCC gasoline is the key to reducing the sulfur content of finished gasoline.

Sulfur in gasoline includes mercaptans, sulfides, disulfides and thiophenes (including thiophene and thiophene derivatives). In the standard of gasoline as fuel, the mercaptan sulfur content and the total sulfur content are stipulated the maximum limit. When the mercaptan sulfur content exceeds the standard or the total sulfur content exceeds the standard, gasoline must be sweetened or desulfurized.

Gasoline desulfurization often adopts a combination of hydrogenation and non-hydrogenation treatment. For example, one method is to fractionate the whole fraction of gasoline into light and heavy parts. Hydrogen is used for desulfurization, and another method is to convert mercaptans into high-boiling sulfides, and concentrate most of the sulfides into heavy fractions by fractional distillation.

In terms of sweetening, lye extraction is a traditional method for refining hydrocarbon materials, which is widely used in the treatment of liquefied petroleum gas, gasoline, diesel oil, naphtha, alkanes, olefins and other hydrocarbon materials. When the hydrocarbon fluid comes into contact with the lye, the mercaptans in the hydrocarbon stream are removed from the oil by reacting with the lye to form mercaptides. And if the lye containing mercaptide is discharged directly, it is neither economical nor environmentally friendly. Oxidation is usually used to oxidize mercaptides to disulfides so that the lye containing mercaptides can be regenerated. By injecting air and an oxidation catalyst into the used lye, the mercaptide dissolved in the lye is oxidized into disulfide, thereby regenerating the lye, and the regenerated lye is separated by sedimentation or extracted with a hydrocarbon solvent Extract the disulfide in the regenerated lye and continue to use it, thereby greatly reducing the discharge of spent caustic soda.

The lye extraction generally includes the following continuous basic steps: (1) extraction, (2) oxidation, (3) phase separation. In the extraction system, the lye is contacted with the hydrocarbon stream to absorb the mercaptans from the hydrocarbon stream, and the mercaptan and the lye react to form mercaptides; in the oxidation system, the lye containing mercaptides from the extraction system is combined with The injected air and the oxidation catalyst are mixed, and the mercaptide in the lye is oxidized to disulfide; The sulfide phase is separated, or the mixture is mixed with an organic hydrocarbon solvent and then settled to separate the regenerated lye from the disulfide-containing solvent phase, usually the remaining air from the oxidation system is released here, and it is separated from the disulfide The regenerated lye from phase separation is returned to the extraction system for continued use.

In the prior art, it should be pointed out that in the oxidation system of alkaline extraction, in order to completely regenerate the alkaline solution containing thiolate, excess air is usually injected, and the excess air usually flows into the phase together with the alkaline solution. Separation systems, released in phase separation systems. This has two disadvantages: one is that the air flowing into the phase separation system is easy to form bubbles in the lye, which affects the sedimentation and separation of the regenerated lye and the disulfide phase or the solvent phase containing disulfide, so that the regenerated lye is still entrained. There are disulfides or solvents containing disulfides. When the regenerated lye is returned to the extraction system for recycling, the disulfides will be back-extracted into the gasoline raw material, and it is difficult to achieve the purpose of treating gasoline with lye for desulfurization; the second is It is difficult to completely remove the air contained in the regenerated lye or the fresh lye injected in the oxidation system. When the regenerated lye is returned to the extraction system for recycling, at least a part of the mercaptan in the hydrocarbon stream will be contained in the air in the lye and subsequently The disulfides generated under the action of the oxidation catalyst in the alkali liquor cycle remain in the hydrocarbon stream but are not absorbed into the alkali liquor, so the desulfurization effect is not obvious. When using the extraction process to treat light fractions, the disulfides produced during the alkali liquor regeneration process are usually extracted and removed with reformed naphtha, and the reformed naphtha extracted with disulfides needs to be sent out of the device to Reformer processing.

CN101275085A discloses a combined method for desulfurization of gasoline. The method comprises cutting gasoline into light and heavy fractions, and the heavy fraction is divided into large and small fluids. The light fraction is contacted with lye, and the mercaptan in the light fraction is It is extracted into the lye to generate mercaptide, and the mercaptide in the lye is oxidized to disulfide, so that the lye is regenerated to obtain a mixture of regenerated lye and disulfide, and the above-mentioned small part of the heavy fraction As a back-extraction solvent, absorb the disulfides generated during the lye extraction process of light fractions, and mix the small part of heavy fractions containing disulfides with most of the above-mentioned heavy fractions for selective hydrogenation treatment.

The disadvantage of this method is that the heavy fraction used as the back extraction solvent contains surface active substances and is easy to form colloidal heteroatom ring compounds such as phenol, thiophenol, aniline, etc., and the emulsification is serious when it is separated from the regenerated lye by sedimentation. In this way, the heavy fraction after back-extraction carries more lye, and the regenerated lye after back-extraction carries more heavy fraction. After the extraction, the demercaptan rate and desulfurization rate decrease. On the other hand, the coalescence efficiency decreases when the back-extracted heavy fraction flows into the subsequent coalescer for treatment, and the service life of the coalescer is shortened, which affects the selectivity. The hydrogen catalyst is less active due to more deposition of base. In particular, the desulfurization activity of the selective hydrogenation catalyst used in the method is not very high, and it is difficult to obtain a product with a sulfur content not greater than 50 μg/g.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned defects in the prior art and provide a new method for gasoline desulfurization. The method provided by the invention can effectively desulfurize gasoline raw materials. In addition, while effectively reducing the sulfur content in gasoline, It can effectively avoid the loss of octane number and obtain high-quality gasoline.

The invention provides a method for gasoline desulfurization, wherein the method comprises the following steps:

(1) gasoline is cut and fractionated at a cut point temperature of 30-120°C to obtain a heavy fraction with a relatively high boiling range and a light fraction with a relatively low boiling range;

(2) Under selective hydrodesulfurization conditions, the heavy fraction obtained in step (1) and hydrogen are contacted with a hydrodesulfurization catalyst to carry out selective hydrodesulfurization to obtain a desulfurized heavy fraction;

(3) The light fraction obtained in step (1) is contacted with lye to carry out desulfurization of the light fraction. The conditions of contact make the sulfide in the light fraction be extracted into the lye to generate sulfide salt, and then phase separation is carried out to obtain absorption Sulfide-free lye and desulfurized light distillate;

(4) under oxidation conditions, the lye that has absorbed the sulfide obtained in step (3) and the oxidizing agent are contacted with an oxidation catalyst to regenerate the lye, and the salt of the sulfide in the lye is oxidized into a disulfide, Obtain the regenerated lye and discharge the tail gas;

(5) The regenerated lye obtained in step (4) is contacted with a part of the desulfurized heavy fraction obtained in step (2) to carry out lye desulfurization, and the conditions of contact make the disulfide in the lye be desulfurized Extracting into the desulfurized heavy fraction, and then performing phase separation to obtain the heavy fraction that has absorbed the disulfide and the lye after desulfurization;

(6) At least a part of the heavy fraction that has absorbed disulfides obtained in step (5) is returned to step (2) to carry out the selective hydrodesulfurization or is reused in step (5) with the step ( 2) A part of the desulfurized heavy fraction obtained is mixed, and after repeated lye desulfurization, return to step (2);

(7) Mix the desulfurized heavy fraction obtained in step (2) with the desulfurized light fraction obtained in step (3) to obtain a product.

The method for gasoline desulfurization provided by the present invention is a combined process combining hydrogenation and non-hydrogenation treatment. The heavy fraction after hydrogenation used in the present invention is more easily separated from the lye than the non-hydrogenated heavy fraction (used as back extraction solvent Because the heavy fraction contains surface-active substances and is easy to form colloidal heteroatom ring compounds such as phenol, thiophenol, aniline, etc., the emulsification phenomenon is serious when the heavy fraction without hydrogenation treatment is separated from the regenerated lye by sedimentation) At the same time, a part of the desulfurized heavy fraction is used to extract and remove the disulfide in the regenerated lye and the residual oxygen-containing gas entrained by the lye after exhaust gas, so that the disulfide in the light fraction can be effectively avoided. The mercaptan is returned to the lye after desulfurization in the lye extraction step in the extraction system (the lye after desulfurization is preferably returned to the lye extraction step), and the oxidation of oxygen entrained remains in the form of disulfide However, the distillate was not absorbed into the lye in the form of sulfide salt, which ensured the effective desulfurization of the light fraction and maximized the extraction effect of the mercaptan in the light fraction by the lye; The heavy fraction of the regenerated lye is extracted to absorb the disulfide in the lye, and mixed with the heavy fraction from the fractionation system for selective hydrodesulfurization in the hydrogenation system. On the one hand, it does not need During the alkali liquor regeneration process, the reformed naphtha is used to extract and remove the disulfide produced, which needs to be sent out of the device, such as sent to the reforming device for treatment, but mixed with the heavy fraction from the fractionation system in the hydrogenation system Selective hydrodesulfurization treatment, on the other hand, because the surface active substances contained in the heavy fraction after desulfurization have basically been removed by hydrogenation, so it is easier to separate from the lye after absorbing the disulfide in the lye, The lye that may be carried is less, so when it is mixed with the heavy fraction from the fractionation system into the hydrogenation system for treatment, it can effectively avoid the deactivation of the selective hydrogenation catalyst in the present invention due to the large deposition of alkali.

Other features and advantages of the present invention will be described in detail in the following detailed description.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the description, together with the following specific embodiments, are used to explain the present invention, but do not constitute a limitation to the present invention. In the attached picture:

Fig. 1 is a process flow chart of the gasoline desulfurization method provided by the present invention.

Detailed ways

Specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

The method for gasoline desulfurization provided by the invention comprises the following steps:

(1) cutting and fractionating gasoline at a cut point temperature of 30-120° C., preferably 40-80° C., to obtain a heavy fraction with a relatively high boiling range and a light fraction with a relatively low boiling range;

(2) Under selective hydrodesulfurization conditions, the heavy fraction obtained in step (1) and hydrogen are contacted with a hydrodesulfurization catalyst to carry out selective hydrodesulfurization to obtain a desulfurized heavy fraction;

(3) The light fraction obtained in step (1) is contacted with lye to carry out desulfurization of the light fraction. The conditions of contact make the sulfide in the light fraction be extracted into the lye to generate sulfide salt, and then phase separation is carried out to obtain absorption Sulfide-free lye and desulfurized light distillate;

(4) under oxidation conditions, the lye that has absorbed the sulfide obtained in step (3) and the oxidizing agent are contacted with an oxidation catalyst to regenerate the lye, and the salt of the sulfide in the lye is oxidized into a disulfide, Obtain the regenerated lye and discharge the tail gas;

(5) The regenerated lye obtained in step (4) is contacted with a part of the desulfurized heavy fraction obtained in step (2) to carry out lye desulfurization, and the conditions of contact make the disulfide in the lye be desulfurized Extracting into the desulfurized heavy fraction, and then performing phase separation to obtain the heavy fraction that has absorbed the disulfide and the lye after desulfurization;

(6) At least a part of the heavy fraction that has absorbed disulfides obtained in step (5) is returned to step (2) to carry out the selective hydrodesulfurization or is reused in step (5) with the step ( 2) A part of the desulfurized heavy fraction obtained is mixed, and after repeated lye desulfurization, return to step (2);

(7) Mix the desulfurized heavy fraction obtained in step (2) with the desulfurized light fraction obtained in step (3) to obtain a product.

According to the present invention, in step (1), the method for cutting gasoline into light fractions and heavy fractions at a cut point temperature of 30-120° C., preferably 40-80° C., can be a conventionally used cutting technique in the art, for example , cut through a fractionation tower, in which the light fraction concentrates most of the mercaptans and olefins in gasoline, and the heavy fraction concentrates most of the other sulfur compounds in gasoline and contains a small amount of mercaptans.

Wherein, the gasoline raw material can be various gasoline raw materials that need to be desulfurized, for example, it can be selected from one of catalytic cracking (FCC) gasoline, catalytic cracking gasoline, straight-run gasoline, coker gasoline, pyrolysis gasoline and thermal cracking gasoline or more.

According to the present invention, the yields of the light fraction and the heavy fraction obtained by cutting at the cut point temperature are 10-60% by weight and 40-90% by weight of the gasoline feedstock, respectively.

According to the present invention, in step (2), under selective hydrodesulfurization conditions, the heavy fraction and hydrogen obtained in step (1) are contacted with hydrodesulfurization catalysts to carry out selective hydrodesulfurization conditions. Selective hydrodesulfurization conditions, and the required desulfurization conditions can be adjusted appropriately according to the degree of desulfurization. For example, the conditions for the selective hydrodesulfurization include hydrogen partial pressure of 0.1-4MPa, preferably 1-3.2MPa; reaction temperature of 100-450°C, preferably 200-350°C; liquid hourly space velocity of 1 -10h ^-1 , preferably 2-6h ^-1 , hydrogen oil volume ratio can be 200-1000Nm ³ /m ³ , preferably 200-600Nm ³ /m ³ .

According to the present invention, in step (2), the hydrodesulfurization catalyst can be various conventional hydrodesulfurization catalysts in the field that can be used to remove most of other sulfides and a small amount of mercaptan in the heavy fraction. For example, the hydrodesulfurization catalyst generally contains a support and a hydrodesulfurization active component loaded on the support, based on the total weight of the catalyst, the content of the support is 60-99%, calculated as oxides, The content of the hydrodesulfurization active component is 1-40%.

Wherein, the hydrodesulfurization active component can generally be selected from one or more of Group VIB metals and Group VIII non-noble metals, preferably, the hydrodesulfurization active component is molybdenum and/or tungsten and nickel and/or cobalt.

The carrier can be various conventionally used carriers, that is, various heat-resistant porous materials commonly used in the art, specifically, the heat-resistant porous material can be heat-resistant inorganic oxides and/or silicic acid Salt, preferably, the carrier is one or more of alumina, silica, titania, magnesia, zirconia, thoria, beryllium oxide, clay and molecular sieves. More preferably, the carrier is one or more of alumina, silica and large or medium pore zeolite molecular sieves.

Preferably, based on the total weight of the catalyst, the content of the carrier is 69-97.8% by weight, and the content of molybdenum and/or tungsten can be 2-25% by weight in terms of oxides, nickel and/or Or the content of cobalt may be 0.2-6% by weight.

In the present invention, the content of molybdenum and/or tungsten (nickel and/or cobalt) refers to the total content of molybdenum and tungsten (or nickel and cobalt), that is, when the hydrodesulfurization active component contains both molybdenum and tungsten (or nickel and cobalt), the content represents the total content of molybdenum and tungsten (or nickel and cobalt); when the hydrodesulfurization active component contains molybdenum but does not contain tungsten (or contains nickel but does not contain cobalt) , the content represents the content of molybdenum (or nickel); when the hydrodesulfurization active component contains tungsten but does not contain molybdenum (or contains cobalt but does not contain nickel), the content represents the content of tungsten (or cobalt).

The hydrodesulfurization catalyst described in the present invention can be prepared with reference to various methods in the prior art, for example, it can be prepared by a conventional impregnation method, such as a dry impregnation method (ie equal volume impregnation method), the dry impregnation method It can be carried out as follows: one or more metal salt solutions selected from Group VIB metals and Group VIII non-noble metals, preferably molybdenum salts and/or tungsten salts and nickel salts and/or cobalt salt solutions (such as removing Ionic aqueous solution) is in contact with the carrier, so that in the finally formed hydrodesulfurization catalyst, the content of one or more metals selected from Group VIB metals and Group VIII non-noble metals can be 1-40% by weight in terms of oxides , preferably, based on oxides, the content of molybdenum and/or tungsten can be 2-25% by weight, and the content of nickel and/or cobalt can be 0.2-6% by weight. Then dry and roast to obtain the hydrodesulfurization catalyst described in the present invention.

Wherein, one or more metal salt solutions selected from Group VIB metals and Group VIII non-noble metals, preferably molybdenum salts and/or tungsten salts and nickel salts and/or cobalt salt solutions (such as deionized aqueous solution) and The carrier contact method can be carried out in the following two ways: (1) one or more metal salts selected from Group VIB metals and Group VIII non-noble metals, preferably molybdenum salts and/or tungsten salts and nickel salts and/or cobalt salt to form a mixed aqueous solution and then the carrier is immersed therein; (2) one or more metals selected from Group VIB metals and Group VIII non-noble metals, preferably molybdenum salts and/or The tungsten salt, the nickel salt and/or the cobalt salt are each formulated into an aqueous solution, and then the carrier is sequentially contacted with the selected salt solution (the order of contact is selected arbitrarily).

According to the present invention, one or more metal salts selected from Group VIB metals and Group VIII non-noble metals are water-soluble salts thereof, wherein the molybdenum salts can be various water-soluble molybdenum salts, such as heptamolybdenum One or more of various water-soluble molybdenum salts commonly used such as ammonium tetramolybdate, ammonium dimolybdate, etc.; the tungsten salt can be various water-soluble tungsten salts, such as ammonium tungstate , ammonium metatungstate, ethyl ammonium metatungstate, thioammonium tungstate, nickel metatungstate and other commonly used water-soluble tungsten salts; the nickel salt is a variety of water-soluble nickel Salt, as can be one or more in the various water-soluble nickel salts commonly used such as nickel nitrate, nickel chloride, nickel sulfate, basic nickel carbonate; Described cobalt salt is various water-soluble cobalt salts, as can It is one or more of various water-soluble cobalt salts commonly used such as cobalt nitrate, cobalt chloride, and basic cobalt carbonate.

The present invention has no special requirements on the methods and conditions of the drying and roasting, which can be carried out with reference to conventional methods and conditions in the art. For example, the drying temperature may be 80-200° C., and the drying time may be 1-10 hours. The firing temperature can be 300-800°C, preferably 400-700°C; the firing time can be 1-8 hours, preferably 2-6 hours.

Preferably, the selective hydrodesulfurization reaction of the heavy fraction and hydrogen in contact with the hydrodesulfurization catalyst may include two reaction stages, the first reaction stage is low-temperature hydrogenation, which is used to remove diolefins in gasoline to prevent Polymerization coking caused by diolefins, the temperature of the first reaction stage is preferably 150-300°C, the hydrogen partial pressure is preferably 1-3.2MPa, the liquid hourly space velocity is preferably 2-6h ^-1 , and the hydrogen-to-oil volume ratio is preferably 200 -600Nm ³ /m ³ ; the second reaction stage is selective hydrodesulfurization, the temperature of the second reaction stage is preferably 250-350°C, the hydrogen partial pressure is preferably 1-3.2MPa, and the liquid hourly space velocity is preferably 2-6h ^{- 1.} The volume ratio of hydrogen to oil is preferably 200-600Nm ³ /m ³ .

In addition, the types of hydrodesulfurization catalysts in the first reaction stage and the second reaction stage can be the same or different. Preferably, in order to further achieve a better hydrodesulfurization effect, in the first reaction stage and the second reaction stage Hydrodesulfurization catalysts with different activities are used. For example, low-activity hydrogenation catalysts are used in the first reaction stage, and the active components of hydrodesulfurization are molybdenum and/or tungsten. High-activity hydrogenation catalysts are used in the second stage. is nickel and/or cobalt.

According to the present invention, in step (3), the light fraction obtained in step (1) is contacted with lye to carry out desulfurization of the light fraction, and the conditions of the contact only need to ensure that the sulfide in the light fraction is extracted into the lye to generate sulfide The salt of the substance can be used, and the required contact conditions can be adjusted appropriately according to the degree of extraction. For example, the conditions of the contact may include temperature and pressure of the contact, wherein the temperature and pressure of the contact can be selected in a wide range, for example, the temperature of the contact may be minus 10°C to 100°C, preferably 0°C. -50°C; the pressure can be 0.1-2MPa, preferably 0.1-1MPa.

In the present invention, as long as the concentration and dosage of the lye can ensure that the mercaptan in the light fraction can be fully extracted into the lye, preferably, the volume ratio of the light fraction to the lye can be 1 : 0.01-10, preferably 1: 0.05-1, more preferably 1: 0.1-0.5.

类化合物以及各种碱性氮化物等常规使用的助剂中的一种或多种，以碱液的总重量为基准，所述助剂的含量通常不超过1000μg/g，优选不超过500μg/g。Wherein, in step (3), the lye can be various conventional known alkaline reagents in the art that have the ability to extract sulfides from gasoline, mainly mercaptans, for example, the lye Can be selected from one or more of aqueous ammonia and alkali metal hydroxides, wherein the alkali metal hydroxides can be one or more of sodium hydroxide, potassium hydroxide and lithium hydroxide kind. Wherein, the concentration of ammonia water can be 1-30% by weight, preferably 5-25% by weight; the concentration of the aqueous solution of alkali metal hydroxide can be 1-50% by weight, preferably 5-25% by weight. In addition, the lye may also contain additives to promote the absorption of mercaptans in the light fraction by the lye to effectively improve the desulfurization of the light fraction; , ethanol and isopropanol, etc.), nitrogen, phosphorus, oxygen, sulfur, arsenic, antimony

One or more of conventionally used additives such as compounds and various basic nitrides, based on the total weight of the lye, the content of the additives is usually no more than 1000 μg/g, preferably no more than 500 μg/g g.

According to the present invention, in step (3), the method for performing phase separation to obtain the lye that has absorbed the sulfide and the light fraction after desulfurization can be a phase separation method known to those skilled in the art, for example, sedimentation separation and the like.

According to the present invention, preferably, the lye in step (3) contains the desulfurized lye from step (5). That is, in order to facilitate the circulation and continuous operation of the system, at least a part of the desulfurized lye obtained in step (5) can be returned to step (3) to carry out the desulfurization of the light fraction, so as to be recycled for extracting the light fraction sulfides in.

According to the present invention, in step (4), under oxidation conditions, the lye that has absorbed the sulfide obtained in step (3) and the oxidizing agent are contacted with an oxidation catalyst to regenerate the lye, so that the sulfide in the lye The contact conditions for oxidation of salts (mainly mercaptides) into disulfides can be conventional conditions in the art. For example, the contact conditions can include contact temperature and pressure, and the contact temperature can be 0- 100°C, preferably 0-80°C; pressure can be 0.1-2MPa, preferably 0.1-1MPa. Preferably, the pressure in step (4) is generally lower than that in step (3) where the light fraction is contacted with alkali liquor to desulfurize the light fraction.

According to the present invention, in step (4), the oxidation catalyst can be various conventional ones in the art that can be used to oxidize the salt of sulfide in the lye containing the salt of sulfide (mercaptide) into disulfide oxidation catalysts. Preferably, the active component of the oxidation catalyst is a metal phthalocyanine compound.

According to the present invention, in step (4), the content of the oxidation catalyst only needs to be able to catalyze the oxidant to oxidize the sulfide salt in the lye into disulfide.

Wherein, the oxidation catalyst can be used in any method known in the art, for example, by dissolving the metal phthalocyanine compound in lye or mixing the metal phthalocyanine compound with lye to obtain a stable emulsion The metal phthalocyanine compound can also be used in the form of a supported oxidation catalyst by supporting the metal phthalocyanine compound on a carrier.

For example, when the metal phthalocyanine compound is dissolved in lye or mixed with lye to obtain a stable emulsion, the content of the metal phthalocyanine compound in the lye can be 5-1000 μg/g, Preferably 10-400 μg/g.

For example, when the metal phthalocyanine compound is used in the form of a supported oxidation catalyst, the supported oxidation catalyst contains a carrier and an active component loaded on the carrier, and the carrier can be various conventional oxidation catalysts in the art The porous material, the active component is a metal phthalocyanine compound; based on the total weight of the catalyst, the content of the carrier can be 90-99.9% by weight, preferably 95-99.9% by weight; the metal phthalocyanine The content of the compound may be 0.1-10% by weight, preferably 0.1-5% by weight.

According to the present invention, in step (4), the oxygen-containing gas that oxidizes the salt of sulfide to disulfide can be various oxygen-containing gases, and the oxygen content of the oxygen-containing gas is at least 1% by volume, preferably 10% by volume or more, more preferably 10-50% by volume. The oxygen-containing gas may be air (including oxygen-depleted air and oxygen-enriched air) or oxygen. The amount of said oxygen-containing gas is at least equal to the stoichiometric amount required to oxidize the sulfide salt contained in the lye to disulfide, usually 2-4 times the required stoichiometric amount. After oxidation treatment, the sulfide salt in the lye is converted into disulfide, and the lye is thus regenerated.

In step (4), discharge the lye containing sulfide salt obtained in step (3) and the tail gas after contacting the oxygen-containing gas with the oxidation catalyst, which can effectively avoid the entrainment of air bubbles in the lye and affect the desulfurization of subsequent recycling The desulfurization effect of the final lye and the desulfurization effect of the light fraction.

According to the present invention, in order to facilitate the continuous circulation operation of the system, in the step (5), the heavy fraction after desulfurization for extracting the disulfide in the regenerated lye is described as a part of the obtained step (2). The heavy fraction after desulfurization, the specific amount of the heavy fraction after desulfurization used to extract the disulfide in the regenerated lye can be determined according to the actual amount of the regenerated lye and the content of the disulfide therein, as long as It can make the disulfide in the regenerated lye be extracted into the heavy fraction after desulfurization, preferably, in the step (5), it is used to extract the disulfide in the regenerated lye The weight ratio of the desulfurized heavy fraction obtained in the step (2) of the sulfide to all the desulfurized heavy fraction is 1:10-500, preferably 1:50-200.

According to the present invention, the conditions for contacting the regenerated lye obtained in step (4) with the heavy fraction after a part of desulfurization obtained in step (2) are as long as the disulfide in the regenerated lye is extracted It can be added to the heavy fraction after the partial desulfurization. Preferably, in step (5), the conditions of the contact include temperature and pressure, the adjustable range of the contact temperature and pressure is wide, the higher the temperature and the greater the pressure, the more conducive to the extraction of disulfides, However, the improvement of the extraction effect is not obvious when the temperature and pressure are too high. Therefore, preferably, the temperature can be 0-100°C, preferably 0-80°C; the pressure can be 0.1-2MPa, preferably 0.1 -1MPa.

According to the present invention, the mode of contacting the regenerated lye obtained in step (4) with the heavy fraction after a part of desulfurization obtained in step (2) can adopt various known methods, such as cocurrent contact mixing, countercurrent Contact mixing, etc., for example, the contact method can be a static mixing method without a medium, or an orifice plate, a particle filler (such as a ceramic ball, a nickel ring, etc.), a metal fiber or a non-metallic fiber (filament or bundle) The contact mode of being a medium, and the contact mode using a supported oxidation catalyst as a medium, wherein the supported oxidation catalyst can be a supported oxidation catalyst in which the metal phthalocyanine compound is used in the form of a supported oxidation catalyst as described above .

In the present invention, the ratio of the regenerated lye obtained in step (4) to the desulfurized heavy fraction obtained in step (2) is not particularly limited, and the amount of the desulfurized heavy fraction obtained in this part of step (2) It can be determined according to the amount of the disulfide in the regenerated lye, as long as it can be guaranteed that the disulfide in the regenerated lye can be fully extracted into the heavy fraction, preferably, step (4) The volume ratio of the obtained regenerated lye to the heavy fraction after desulfurization obtained in the partial step (2) is 1-500:1, more preferably 5-200:1, further preferably 10-50:1.

According to the present invention, in step (5), the method for said phase separation can be the method conventionally used in the art, as long as it can be guaranteed that the heavy fraction and desulfurized lye that have absorbed the disulfide can be obtained, for example, Separation by gravity settling.

In step (5), when the disulfide in the lye is extracted into the heavy fraction after desulfurization and phase separation is carried out, the liquid fluid is divided into upper and lower layers, and the upper layer is the heavy fraction containing disulfide The oil phase, the lower layer is the alkali liquid phase after desulfurization. That is, during the process of extraction and phase separation, the disulfides are precipitated from the lye and back-extracted into the desulfurized heavy fraction of the upper layer, and after phase separation, the desulfurized lye that does not contain oxygen is obtained. and heavy fractions that absorb disulfides.

When phase separation is carried out, it is usually carried out in a phase separation system, such as a sedimentation separation system, usually using fillers such as steel wire, sand, glass, coke, etc. as coalescents to promote the coalescence of disulfides into heavy fractions, the contact 1. Extraction to realize the residence time of phase separation as long as sufficient extraction can be ensured, preferably 0.5-2 hours, to further promote the sufficient progress of phase separation. In addition, when performing phase separation (sedimentation separation), the residual oxygen-containing gas carried in the lye can be further released.

According to the present invention, in order to recycle the heavy fraction that has absorbed disulfide obtained in step (5) and ensure the yield of gasoline after desulfurization, the method also includes at least a part of the absorbed disulfide obtained in step (5). The disulfide-removed heavy fraction is returned to step (2) for the selective hydrodesulfurization or is reused in step (5) for a part of the desulfurized heavy fraction obtained from step (2), and repeated After the lye is regenerated, that is, it is used to extract the disulfide in the lye again, and then returns to the step (2).

The amount of at least a part of the heavy fraction that has absorbed disulfides obtained in the step (5) is not particularly limited, and can be determined according to actual conditions, for example, according to the amount of disulfides in the regenerated lye or the step ( 5) The content of the disulfide in the heavy fraction that has absorbed the disulfide is determined according to its extraction capacity when it is extracted again.

According to the present invention, preferably, in order to be more conducive to the selective hydrodesulfurization treatment of heavy fractions, after step (5) and before step (6), the method also includes absorbing disulfide obtained in step (5) The heavy distillate is coalesced to remove trace lye and other mechanical impurities contained in it. The method for the coalescence treatment can be a coalescence treatment method known to those skilled in the art, for example, the heavy fraction that has absorbed the disulfide is mixed with a coalescence agent (usually using fillers such as steel wire, sand, glass, coke, etc. as a coalescent) to promote the adsorption of trace amounts of lye and other mechanical impurities on the coalescent, and the residence time of the contact can be 0.1-2 hours.

According to the present invention, preferably, the method also includes contacting the heavy fraction obtained in step (5) that has absorbed disulfide with the tail gas produced in step (4), so as to absorb the sulfur-containing light hydrocarbons in the tail gas, and The heavy fraction that has absorbed disulfides and sulfur-containing light hydrocarbons is returned to step (2) for the selective hydrodesulfurization. The tail gas obtained can be passed through a light hydrocarbon recovery device for recovering traces of light hydrocarbons that flow out with the air in the alkali liquor (for example, heavy hydrocarbon oil is used as a recovery tank for recovery agent, etc.).

Preferably, in order to recycle the heavy fraction that has absorbed disulfides and sulfur-containing light hydrocarbons, the heavy fraction that has absorbed disulfides and sulfur-containing light hydrocarbons is returned to step (2) to carry out the Selective hydrodesulfurization.

According to the present invention, after gasoline is desulfurized by the method of the present invention, the mercaptan sulfur content in the desulfurized heavy fraction obtained is relatively low, usually between 1-50 μg/g, preferably, according to actual production needs , in order to further obtain a product with a mercaptan sulfur content not greater than 10 μg/g, the method further includes mixing the desulfurized heavy fraction obtained in step (2) with the desulfurized light fraction obtained in step (3) to obtain Before the product, deodorize the mixture of the desulfurized heavy fraction obtained in step (2) and the desulfurized light fraction obtained in step (3); or deodorize the desulfurized light fraction obtained in step (2) The heavy fraction is deodorized and then mixed with the desulfurized light fraction obtained in step (3) to obtain a product, so that the mercaptan sulfur content of the obtained product is not greater than 10 μg/g. Wherein, the purpose of the deodorization is to use catalytic oxidation to remove the mercaptans that are too late to be hydrogenated and newly formed mercaptans in the heavy fraction during the hydrogenation process, so as to further ensure that the mercaptan sulfur content in the refined gasoline product is not greater than 10 μg/g.

According to the present invention, after adopting the method of the present invention to desulfurize gasoline, gasoline products with reduced total sulfur content can also be obtained. For example, the sulfur content of the obtained gasoline products can meet the national No. The content is not more than 150 μg/g and meets the requirements of the National No. IV Emission Standard for the sulfur content of motor gasoline not greater than 50 μg/g. Preferably, the sulfur content of the obtained gasoline products meets the expected future National No. V Emission Standard for vehicles. The requirement that the sulfur content in gasoline is not greater than 10μg/g.

According to the present invention, when producing gasoline products with a target sulfur content of no more than 10 μg/g, the weight of the total sulfur content of the light fraction after desulfurization is required to be at least no greater than 10 μg/g, and the weight of the total sulfur content of the heavy fraction after desulfurization is required At least not more than 10μg/g. For this reason, the weight of the sulfur content (including mercaptan sulfur) in the light fraction after desulfurization can be adjusted by flexibly adjusting the cut point temperature of the light fraction and the heavy fraction. After selective hydrotreating, the weight of sulfur content (including mercaptan sulfur) is not greater than 10 μg/g, and the light fraction after desulfurization and the heavy fraction after desulfurization are mixed in step (7) to obtain sulfur and mercaptan sulfur For products with a content of no more than 10 μg/g, according to the current regulations on the mercaptan sulfur index of gasoline products not exceeding 10 μg/g, the heavy fraction after selective hydrotreating and the light fraction after sweetening do not need to undergo catalytic oxidation after mixing Deodorized and refined directly into low-sulfur gasoline products with a sulfur content not greater than 10 μg/g.

In addition, the desulfurized heavy distillate obtained in step (2) is mixed with the desulfurized light distillate obtained in step (3) to obtain the product, which refers to direct mixing when the weight of the sulfur content of the two is not greater than 10 μg/g A motor gasoline product that meets the sulfur content requirements of the expected National V emission standard is obtained. If the sum of the sulfur content weights of the two is greater than 10μg/g (such as the production of gasoline products that meet the National III or National IV emission standards), and the weight of the sulfur content of the two mercaptans is not greater than 10μg/g, it is not necessary Deodorization treatment, directly mixed to obtain the product, otherwise deodorization treatment is required to ensure that the mercaptan sulfur content of the product is not greater than 10 μg/g.

The deodorization method can be carried out by methods known to those skilled in the art, for example, it can be carried out by liquid-liquid catalytic oxidation, or by fixed-bed catalytic oxidation.

If the way of liquid-liquid catalytic oxidation is adopted, the oxidation catalyst is a metal phthalocyanine compound dissolved in lye or forming a stable emulsion in lye, and the content of the metal phthalocyanine compound in lye can be 5- 1000 μg/g, preferably 10-500 μg/g. The oxidizing agent is an oxygen-containing gas, and the oxygen-containing gas is as defined in the foregoing description of the present invention, preferably purified air, the amount of which is at least equal to the oxidation of mercaptans and newly formed mercaptans in the heavy fraction after hydrogenation that are too late to undergo hydrogenation. The stoichiometric amount required for the sulfide is preferably 2-4 times the stoichiometric amount required for the oxidation of mercaptans into disulfides; the oxidizing agent can also be selected or matched with an oxidizing inorganic or organic oxygen-containing compound , such as hydrogen peroxide, etc.

If the method of fixed bed catalytic oxidation is adopted, the fixed bed deodorization catalyst is a metal phthalocyanine compound supported on a porous material. Preferably, the method of fixed bed catalytic oxidation is used. The fixed-bed deodorization system is a mixture of the desulfurized heavy fraction obtained in step (2) and the light fraction obtained in step (3) in the presence of an oxidant (the oxidant is preferably an oxygen-containing gas), and preferably in the presence of an alkaline agent , or the desulfurized heavy fraction obtained in step (2) is contacted with a catalytic amount of a metal phthalocyanine compound supported by a porous material to carry out a deodorization reaction.

Wherein, the pressure of the fixed bed deodorization system may be 0.1-2MPa, preferably 0.2-0.8MPa. The temperature of the fixed bed deodorization system can be minus 10°C to 100°C, preferably 0-80°C, and the liquid hourly space velocity after selective hydrotreatment can be 0.1-10h ^-1 , preferably 0.5-5h ^-1 .

In the fixed bed deodorization catalyst, the carrier can be a porous material of various conventional oxidation catalysts in the art, and the active component is a metal phthalocyanine compound; based on the total weight of the catalyst, the content of the carrier It may be 90-99.9% by weight, preferably 95-99.9% by weight; the content of the metal phthalocyanine compound may be 0.1-10% by weight, preferably 0.1-5% by weight.

The alkaline reagent can be selected from any commonly used alkaline reagent known in the art, for example, an aqueous solution of an inorganic lye and/or a basic organic compound, and the ideal inorganic lye is generally of an alkali metal and/or an alkaline earth metal Aqueous solution of hydroxide and/or ammoniacal liquor, for example, the hydroxide of described alkali metal and alkaline earth metal can be selected from a kind of in sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide and barium hydroxide or Several kinds. The basic organic compound in the aqueous solution of the basic organic compound may be one or more of organic amine compounds, alkaloid compounds and organic quaternary ammonium bases, preferably organic quaternary ammonium bases. The amount of the basic organic compound in the aqueous solution of the basic organic compound may be 0.1-1000 μg/g, preferably 0.5-100 μg/g.

类化合物，所述极性化合物可以选自水、甲醇、乙醇、异丙醇等低碳醇、烷基胺类碱性氮化合物和羟烷基胺类的碱性氮化合物中的一种或多种。所述

类化合物可以是季铵类化合物、

类化合物、

类化合物、锑

类化合物、氧

类化合物及锍

类化合物中的一种或多种，作为阳离子的原子分别是N、P、As、Sb、O和S等，优选为季铵盐和/或季铵碱。以待处理油品(例如，步骤(7)的重馏分与轻馏分的混合物，或者重馏分)的重量为基准，所述催化助剂的量可以为0.1-1000μg/g，优选为0.5-500μg/g。According to the present invention, when performing deodorization, whether it is liquid-liquid catalytic oxidation or fixed-bed catalytic oxidation, it is preferably carried out in the presence of a catalytic promoter (i.e. an activator), and the catalytic promoter can be a polar compound and/or or

The polar compound can be selected from one or more of low carbon alcohols such as water, methanol, ethanol, isopropanol, basic nitrogen compounds of alkylamines and basic nitrogen compounds of hydroxyalkylamines kind. said

Compounds can be quaternary ammonium compounds,

class of compounds,

compounds, antimony

compounds, oxygen

Compounds and sulfonium

One or more of these compounds, the atoms as cations are respectively N, P, As, Sb, O and S, etc., preferably quaternary ammonium salt and/or quaternary ammonium base. Based on the weight of the oil to be treated (for example, the mixture of the heavy fraction and the light fraction in step (7), or the heavy fraction), the amount of the catalytic promoter can be 0.1-1000 μg/g, preferably 0.5-500 μg /g.

The alkaline reagent and the catalyst promoter can be used after being mixed with the gasoline to be treated, or can be impregnated or adsorbed on a catalyst carrier beforehand and used together with the metal phthalocyanine. When the basic reagent is pre-impregnated or adsorbed on the catalyst carrier, its effective weight (mass of solute in the basic reagent) can account for 0.1-40 wt%, preferably 0.1-20 wt%, of the total catalyst weight.

类化合物等。In the present invention, the metal phthalocyanine compound, including the oxidation step of step (4) and the metal phthalocyanine used in the deodorization step of step (7), can be selected from magnesium phthalocyanine, magnesium phthalocyanine, Titanium phthalocyanine, hafnium phthalocyanine, vanadium phthalocyanine, tantalum phthalocyanine, molybdenum phthalocyanine, manganese phthalocyanine, iron phthalocyanine, cobalt phthalocyanine, platinum phthalocyanine, palladium phthalocyanine, copper phthalocyanine, silver phthalocyanine, zinc phthalocyanine One or more of cyanine and tin phthalocyanine, preferably cobalt phthalocyanine and/or vanadium phthalocyanine. The metal phthalocyanine compound may be selected from sulfonates, carboxylates, quaternary ammonium salts and other compounds of metal phthalocyanines.

compounds, etc.

类化合物，优选钴酞菁的季铵盐，其通式为CoPc[N(R₁R₂R₃)A]_a，其中Pc为通用的表示酞菁基本结构的符号，R₁、R₂、R₃为相同或不同的具有1-3个碳原子的烷基，A为卤素阴离子，最优选的为I^-，a为季铵化度，其值为1-4。In the present invention, the metal phthalocyanine used in the deodorization system is preferably a positive-negative ion pair metal phthalocyanine, which is composed of a metal phthalocyanine with a positive ion group and a metal phthalocyanine with an anion group. The metal phthalocyanines with positive ion groups are selected from sulfonates and carboxylates of metal phthalocyanines, preferably sulfonates of cobalt phthalocyanines, including monosulfonates of cobalt phthalocyanines (monosulfonated cobalt phthalocyanines) ), bissulfonate of cobalt phthalocyanine (disulfonated cobalt phthalocyanine), trisulfonate of cobalt phthalocyanine (cobalt trisulfonated phthalocyanine), tetrasulfonate of cobalt phthalocyanine (tetrasulfonated cobalt phthalocyanine Cobalt) or any mixture thereof. The metal phthalocyanine with anion group is selected from the quaternary ammonium salt of metal phthalocyanine,

Compounds, preferably quaternary ammonium salts of cobalt phthalocyanine, whose general formula is CoPc[N(R ₁ R ₂ R ₃ )A] _a , wherein Pc is a general symbol representing the basic structure of phthalocyanine, R ₁ , R ₂ , R ₃ is the same or different alkyl groups with 1-3 carbon atoms, A is a halide anion, most preferably I ⁻ , a is the degree of quaternization, and its value is 1-4.

The carrier of the fixed bed catalyst used in the oxidation step of step (2) and the deodorization step of step (7) can be selected from porous materials containing aluminum, silicon, alkaline earth metals, transition metals, rare earth metals and carbonaceous , such as alumina, silica, aluminosilicate, calcium oxide, magnesium oxide, titanium oxide, natural and artificial clay, natural and artificial zeolite, from mineral materials (such as coal and petroleum, etc.), plant materials (such as wood chips, fruit Shells, fruit cores, etc.) and carbonaceous materials such as synthetic resins, etc., are preferably activated carbon. The specific surface of the porous carrier may generally be 10-1500 m ² /g, preferably 100-1200 m ² /g.

According to a preferred embodiment of the present invention, as shown in Figure 1:

Said Fig. 1 only represents the preferred flow chart, and details such as the control equipment of the relevant container, heater, cooler, pump, compressor, mixer, valve, process are not given, that is to say, it only shows the people who are familiar with the technology. Persons in the art are aware of device conditions that are essential or non-obvious to the present invention.

The raw gasoline enters the fractionation system 2 through the pipeline 1, the gasoline light fraction flows out through the pipeline 4, and the gasoline heavy fraction flows out through the pipeline 3 and then enters the selective hydrodesulfurization system 24, and passes through the first hydrogenation reaction zone under the action of a low-activity hydrogenation catalyst The first selective hydrogenation reaction is carried out, and the second selective hydrogenation reaction is carried out under the action of a high-activity hydrogenation catalyst through the second hydrogenation reaction zone.

The gasoline light fraction from fractionation system 2 enters extraction system 5 via line 4 . Fresh lye or lye containing metal phthalocyanine catalyst (desulfurized lye from the sedimentation separation system 15 (derived from pipeline 16)) enters the extraction system 5 through the pipeline 8, and the light fraction and lye are in the extraction system 5 Countercurrent contact, the sulfides (mercaptans) in the light fraction are extracted into the lye to generate sulfide salts (mercaptides), and the desulfurized light fraction leaves the extraction system 5 through the pipeline 7 .

The lye that has absorbed the sulfide flows into the oxidation and back-extraction system 11 through the pipeline 7, and mixes with the oxidant (oxygen-containing gas) that enters the oxidation and back-extraction system 11 through the pipeline 9 to regenerate the lye. The sulfide salt is oxidized to disulfide to obtain regenerated lye. Usually, if necessary, fresh lye and catalyst can be input through pipeline 8 or 10, and excess oxidant (preferably oxygen-containing gas) is released from the top of oxidation and stripping system 11 through pipeline 12.

The mixture of the regenerated lye and residual oxidant (oxygen-containing gas) from the oxidation system 11 is mixed with a part of the hydrodesulfurized heavy fraction from the selective hydrodesulfurization system 24 (drawn out through the line 26) through the pipeline 13 and flows into the phase. The settling separation system 15 of the separation system makes the disulfide in the regenerated lye be extracted into the heavy fraction after desulfurization, and then phase separation is carried out to obtain the heavy fraction and the desulfurized heavy fraction that have absorbed the disulfide. lye; and further release residual oxygen-containing gas from the top of the settling separation system 15 through the pipeline 14.

After settling and separation, the desulfurized lye flows out from the pipeline 16 and returns to the extraction system 5 for recycling through the pipeline 8, and the heavy disulfide phase that is basically immiscible with the desulfurized lye phase passes through the pipeline 17 Flow out, can continue to mix with the lye after the regeneration of oxidation system 11 through pipeline 18 inflow line 27, flow into sedimentation separation system 15 sedimentation separations, be used continuously for the disulfide in back extraction lye, also can It flows directly into the coalescence removal system 20 through the pipeline 19.

The heavy distillate oil phase that has absorbed the disulfide flows out of the coalescing removal system 20 through the pipeline 22 (to remove the trace lye that may be carried and the impurities are discharged through the pipeline 21), and is combined with the gas from the fractionation system from the pipeline 3 2, and then flow into hydrogenation system 24 together with hydrogen from line 23 for selective hydrodesulfurization.

The heavy distillate is contacted with hydrogen under the action of a low-activity hydrogenation catalyst and a high-activity hydrogenation catalyst to carry out a selective hydrodesulfurization reaction, and then flows out of the hydrogenation system 24 after gas stripping to remove hydrogen sulfide.

The hydrogenated heavy fraction from the hydrogenation system 24 is divided into two parts through the pipeline 25, and a small part of the hydrogenated heavy fraction flows out through the pipeline 26-1, and passes through the pipeline 27 and comes from the oxidation system. The regenerated lye of 11 is mixed through the pipeline 13, and is used for back-extracting the disulfide in the regenerated lye, and most of the remaining heavy fraction after hydrogenation is removed through the pipeline 26-2 and the extraction from the pipeline 6 The light fractions of sulfides (mercaptans) are mixed and mixed with oxygen-containing gas from line 28 and activator (if possible, no activator) from line 29 and then enter the fixed bed deodorization system through line 30 31 for deodorization to remove the sulfides (such as mercaptans) newly formed in the hydrogenation process of the heavy fraction, and the final refined product flows out through the pipeline 32 or after settling.

The preferred embodiment of the present invention has been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the specific details of the above embodiment, within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, These simple modifications all belong to the protection scope of the present invention.

In addition, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way if there is no contradiction. The combination method will not be described separately.

In addition, various combinations of different embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the idea of the present invention, they should also be regarded as the disclosed content of the present invention.

The present invention will be further described in detail through specific examples below.

The two kinds of selective hydrodesulfurization catalysts used in the following examples are provided by Changling Catalyst Factory of China Petroleum & Chemical Corporation Catalyst Branch Company, and the trade marks are respectively RSDS-01 (low activity hydrogenation catalyst) and RSDS-02 (highly active hydrogenation catalyst).

In the following examples, the method for determining the sulfur content is the microcoulomb method known to those skilled in the art.

Example 1

This example is used to illustrate the gasoline desulfurization method provided by the present invention.

In this embodiment, the raw material catalytic cracking gasoline A in Table 1 is processed using the process shown in FIG. 1 .

(1) The cutting fractionation temperature of gasoline A is 75° C., and the heavy fraction with a relatively high boiling range and the light fraction with a relatively low boiling range are obtained. After cutting, the yields of the light fraction B and the heavy fraction C are respectively 38% by weight and 62% by weight. %.

(2) In the selective hydrogenation system, the heavy fraction is subjected to selective hydrogenation treatment. The conditions for the first selective hydrogenation reaction include: the reaction hydrogen partial pressure is 1.6MPa, the reaction temperature is 240°C, and the liquid hourly space velocity is 3.0h ^-1 , the volume ratio of hydrogen to oil is 300Nm ³ /m ³ . The conditions of the second selective hydrogenation reaction include: the reaction hydrogen partial pressure is 1.6MPa, the reaction temperature is 290°C, the liquid hourly space velocity is 3.0h ^-1 , and the volume ratio of hydrogen to oil is 300Nm ³ /m ³ . The hydrogenated heavy fraction is divided into two parts, the weight ratio of a small part of the desulfurized heavy fraction D to a large part of the desulfurized heavy fraction E is 1:75.

(3) In the extraction system, the volume ratio of lye to light fraction B is 0.5:1, the temperature is 20° C., and the pressure is 0.5 MPa.

(4) In the oxidation system, the content of sulfonated phthalocyanine cobalt (purchased from Guangzhou Dayou Fine Chemical Factory) in the lye is 100 μg/g, and the injection amount of the oxygen-containing gas as the oxidant and the lye volume ratio are 1: 4.5, the pressure of the oxidation system is 0.34MPa, and the temperature is 50°C. Wherein, the lye is an aqueous sodium hydroxide solution with a mass percentage concentration of 15%; the oxygen-containing gas is air (the volume content of oxygen is 21%).

(5) In the back-extraction system, the volume ratio of a fraction of the desulfurized heavy fraction D to the regenerated lye for absorbing the disulfide in the regenerated lye is 1:25, and the pressure of the back-extraction system is 0.34MPa, and the temperature is 50°C.

In the phase separation system, the temperature of the sedimentation separation system and the coalescence separation system (the filling medium is polypropylene fiber material) is both natural temperature 25°C, and the pressure is both natural pressure 0.1MPa. After phase separation, the disulfide is absorbed. A small part of heavy fraction D after hydrogenation and alkali liquor after desulfurization; and the small part of heavy fraction D after hydrogenation absorbed by disulfide is mixed with heavy fraction C and enters a selective hydrogenation system for hydrogenation treatment.

(6) After most of the desulfurization, the heavy fraction E is mixed with the light fraction B from the extraction system, and then flows into the fixed bed deodorization system for sweetening treatment. Wherein, the catalyst used in the fixed-bed sweetening system is 1% by weight of cobalt sulfonated phthalocyanine (purchased from Guangzhou Dayou Fine Chemical Factory) supported on activated carbon, the reaction temperature is 40°C, the pressure is 0.3MPa, liquid space-time The speed is 2.0h ^-1 .

The basic properties of raw material A are shown in Table 1, and the results of raw material A after the above-mentioned treatment are shown in Table 1 and Table 2 respectively.

Comparative example 1

This comparative example is used to illustrate the desulfurization method of gasoline in the prior art.

Using the same raw material oil A as in Example 1 and carrying out gasoline desulfurization according to the same combination desulfurization process and the same process parameters as in Example 1, the difference is that in Example 1, it is used in the lye after back extraction and regeneration A small part of disulfide heavy fraction D after desulfurization is replaced by the heavy fraction obtained after cutting and fractionating the raw gasoline in step (1). In addition, in the selective hydrodesulfurization system of step (2), only a single The RSDS-01 catalyst. And, the amount of the heavy fraction obtained after the cut fractionation of the raw gasoline used in step (1) for the disulfide in the lye after back extraction and regeneration is the same as that used in Example 1 for a small part of desulfurization The amount of the latter heavy fraction D is the same, and after stripping the disulfide in the regenerated lye, it is coalesced and mixed with most of the rest of the heavy fraction from the fractionation system, and flows into the hydrogenation system for hydrodesulfurization. After raw material A was treated as above, the results are shown in Table 1 and Table 2 respectively.

Table 1

As can be seen from the results in the above table 1, after being treated by the method provided by the present invention, the desulfurization rate of raw material A is as high as 95.3%, the sulfur content of the product is 40 μg/g, and the sulfur content of gasoline products meeting the National No. Ⅳ emission standard is not more than 50 μg /g requirements, olefin saturation rate is only 21.4%, RON loss is only 1.5 units, while the desulfurization rate of Comparative Example 1 is only 93.8%, product sulfur content is 55 μg/g, olefin saturation rate is 30.0%, RON loss reaches 2.7 units. It can be seen that, compared with Comparative Example 1, the method of Example 1 of the present invention has better desulfurization effect and lower octane number loss.

Table 2

Table 2 has provided the measurement data of sodium mercaptide content in the regenerated lye after desulfurization, and adopts 90-120 ℃ of sherwood oil (sulfur-free) and lye after desulfurization (the lye after desulfurization of embodiment 1 refers to from In the pipeline 18 of Fig. 1, flow out the lye after desulfurization that has been extracted by the heavy fraction after hydrogenation) equal volume mixes and the sulfur content in the lye after the desulfurization measured after separation (in the lye after desulfurization The sulfur content is equal to the measured sulfur content in petroleum ether). The more sodium mercaptide content in the lye after desulfurization, the more unfavorable the extraction and desulfurization of light fractions during reuse. Moreover, the higher the sulfur content in the lye after desulfurization, on the one hand, it means The content of sodium mercaptide may be more, on the other hand, it means that the heavy fraction carried by the lye after desulfurization may be more, which means that the separation effect of lye and heavy fraction in the phase separation system is poor.

As can be seen from the data in Table 1 and Table 2 above, a small portion of the desulfurized heavy fraction D can completely extract the disulfides in the regenerated lye, compared with Comparative Example 1 using a small portion of the non-desulfurized heavy fraction The effect is better.

Compared with the residual sulfur content in the desulfurized lye obtained after the heavy fraction obtained after the fractionation of raw gasoline used in Comparative Example 1 to remove the disulfide in the regenerated lye, the embodiment of the present invention In 1, the heavy fraction after desulfurization is used to extract and remove the disulfide in the regenerated lye, and the residual sulfur content of the desulfurized lye obtained after desulfurization is much smaller, and it is basically sodium mercaptide in the lye Transformed from, it shows that the heavy fraction after desulfurization and the lye after desulfurization are relatively completely separated in the phase separation system. On the contrary, a small amount of heavy fraction is mixed in the lye after desulfurization in Comparative Example 1, showing The increase of the residual sulfur content in the lye means that the separation effect of the heavy fraction and the desulfurized lye in the phase separation system is relatively poor, so this part of the heavy fraction that entrains a trace amount of lye may be unfavorable to the subsequent hydrogenation system Influence.

Example 2

This example is used to illustrate the gasoline desulfurization method provided by the present invention.

In this embodiment, the raw material catalytic cracking gasoline F in Table 3 is treated by the process shown in Fig. 1 .

(1) The cutting fractionation temperature of gasoline F is 60° C. to obtain a heavy fraction with a relatively high boiling range and a light fraction with a relatively low boiling range. After cutting, the yields of the light fraction G and the heavy fraction H are respectively 35% by weight and 65% by weight. %.

(2) In the selective hydrogenation system, the reaction temperature of the first selective hydrogenation reaction is 290°C, the reaction temperature of the second selective hydrogenation reaction is 310°C, and the reaction hydrogen oil volume ratio is 350Nm ³ /m ³ , other conditions are all identical with the step (2) of embodiment 1. The heavy fraction after hydrogenation is divided into two parts, and the weight ratio of a small part of heavy fraction M after hydrogenation to most of heavy fraction N after hydrogenation is about 1:150.

(3) In the extraction system, the volume ratio of lye to light fraction G is 0.1:1, the temperature is 35°C, and the pressure is 0.2MPa.

(4) In the oxidation system, the content of sulfonated phthalocyanine cobalt (purchased from Guangzhou Dayou Fine Chemical Factory) in the lye is 80 μg/g, the injection amount of oxygen-containing gas and the volume ratio of lye are 1: 4.5, and the oxidation The pressure of the system is 0.6MPa, and the temperature is 70°C. Wherein, the lye is an aqueous sodium hydroxide solution with a mass percentage concentration of 15%; the oxygen-containing gas is air (the volume content of oxygen is 21%).

(5) In the back-extraction system, the volume ratio of a small part of desulfurized heavy fraction M for absorbing the disulfide in the regenerated alkali liquor to the regenerated alkali liquor is 1:10. The pressure of the stripping system is 0.6MPa and the temperature is 70°C.

In the phase separation system, the temperature of the sedimentation separation system and the coalescence separation system (filling medium is polypropylene fiber material) is both natural temperature 25 ° C, and the pressure is both natural pressure 0.1 MPa. After phase separation, disulfide is absorbed A small part of the hydrogenated heavy fraction M and the desulfurized lye; and the small part of the hydrogenated heavy fraction M absorbed by the disulfide is mixed with the heavy fraction H and then enters the selective hydrogenation system for hydrogenation.

In addition, close the deodorization system (because the light fraction after sweetening is mixed with the heavy fraction after hydrogenation, the sulfur content is not greater than 10 μg/g, and the sulfur content of mercaptan is not greater than 10 μg/g). The basic properties of raw material F and the results of raw material F after the above treatment are shown in Table 3.

table 3

As can be seen from the results in Table 3, after being processed by the method of the present invention, the desulfurization rate of raw material F all reaches more than 98.2%, and the sulfur content of the product is only 7 μg/g, meeting the sulfur content in the gasoline product of No. V emission standard in the future. Not more than 10 μg/g, but the olefin saturation rate is only 9.8%, and the RON loss is only 0.4 units. It can be seen that the method of Example 2 of the present invention has better desulfurization effect and lower octane number loss.

Claims (17)

1. A method for gasoline desulfurization, characterized in that the method may further comprise the steps: (1) gasoline is cut and fractionated at a cut point temperature of 30-120°C to obtain a heavy fraction with a relatively high boiling range and a light fraction with a relatively low boiling range; (2) Under selective hydrodesulfurization conditions, contacting the fractionated heavy fraction obtained in step (1) and hydrogen with a hydrodesulfurization catalyst to carry out selective hydrodesulfurization to obtain a desulfurized heavy fraction; (3) The fractionated light fraction obtained in step (1) is contacted with lye to desulfurize the light fraction. The conditions of contact make the sulfide in the light fraction be extracted into the lye to generate sulfide salt, and then phase separation Obtain the lye that has absorbed the sulfide and the light distillate after desulfurization; (4) under oxidation conditions, the lye that has absorbed the sulfide obtained in step (3) and the oxidizing agent are contacted with an oxidation catalyst to regenerate the lye, and the salt of the sulfide in the lye is oxidized into a disulfide, Obtain the regenerated lye and discharge the tail gas; (5) The regenerated lye obtained in step (4) is contacted with a part of the desulfurized heavy fraction obtained in step (2) to carry out lye desulfurization, and the conditions of contact make the disulfide in the lye be desulfurized Extracting into the desulfurized heavy fraction, and then performing phase separation to obtain the heavy fraction that has absorbed the disulfide and the lye after desulfurization; (6) At least a part of the heavy fraction that has absorbed disulfides obtained in step (5) is returned to step (2) to carry out the selective hydrodesulfurization or is reused in step (5) with the step ( 2) A part of the desulfurized heavy fraction obtained is mixed, and after repeated lye desulfurization, return to step (2); (7) Mix the desulfurized heavy fraction obtained in step (2) with the desulfurized light fraction obtained in step (3) to obtain a product. 2. The method according to claim 1, wherein, in step (1), the cut fractionation temperature of gasoline is 40-80°C. 3. The method according to claim 1, wherein, in step (1), the yields of the light fraction and the heavy fraction are respectively 10-60% by weight and 40-90% by weight of gasoline. 4. method according to claim 1, wherein, in step (3), the condition of contacting comprises that the temperature of contacting is subzero 10 ℃ to 100 ℃, and pressure is 0.1-2MPa, and the volume of described light distillate and lye The ratio is 1:0.01-10. 5. The method according to claim 1, wherein the lye in the step (3) contains the lye from the desulfurization obtained in the step (5). 6. The method according to claim 1, wherein, in step (4), the active ingredient of the oxidation catalyst is a metal phthalocyanine compound. 7. The method according to claim 1, wherein, in step (4), the oxygen-containing gas is an oxygen-containing gas, and the amount of the oxygen-containing gas is at least equal to making the thiolate contained in the lye oxidized into disulfide The stoichiometric amount required for the substance; the oxygen content of the oxygen-containing gas is at least 1% by volume. 8. The method according to claim 1, wherein, in step (4), the condition that the lye containing the salt of sulfide obtained in the step (3) and the oxidizing agent contact with the oxidation catalyst include that the temperature is 0-100 ℃, the pressure is 0.1-2MPa. 9. The method according to claim 1, wherein, in step (5), the weight of a part of the desulfurized heavy fraction obtained in the step (2) and the weight of the whole desulfurized heavy fraction obtained in the step (2) The ratio is 1:10-500. 10. The method according to claim 9, wherein, in step (5), the weight of a part of the desulfurized heavy fraction obtained in the step (2) and the whole desulfurized heavy fraction obtained in the step (2) The ratio is 1:50-200. 11. method according to claim 9, wherein, in step (5), the condition of contacting comprises that temperature is 0-100 ℃, and pressure is 0.1-2MPa; Step (4) obtains the lye after regeneration and step ( 2) The obtained part of the desulfurized heavy fraction has a volume ratio of 1-500:1. 12. The method according to claim 11, wherein the volume ratio of the regenerated lye obtained in step (4) to a part of the desulfurized heavy fraction obtained in step (2) is 5-200:1. 13. The method according to claim 1, wherein, the method also comprises that a part of the heavy fraction that has absorbed disulfides obtained by step (5) is contacted with the tail gas produced by step (4), absorbing the tail gas containing Sulfur and light hydrocarbons, and the heavy fraction that has absorbed disulfides and sulfur-containing light hydrocarbons is returned to step (2) for the selective hydrodesulfurization. 14. The method according to claim 1, wherein, in step (7), the method further comprises combining the desulfurized heavy fraction obtained in step (2) with the desulfurized heavy fraction obtained in step (3) Before the light fraction is mixed to obtain the product, deodorize the mixture of the desulfurized heavy fraction obtained in step (2) and the desulfurized light fraction obtained in step (3); or deodorize the mixture of the desulfurized light fraction obtained in step (2); The desulfurized heavy fraction is deodorized and then mixed with the desulfurized light fraction obtained in step (3) to obtain a product, so that the mercaptan sulfur content of the obtained product is not greater than 10 μg/g. 15. The method according to claim 1, wherein, in step (7), the mercaptan sulfur content of the obtained product is not greater than 10 μg/g. 16. according to the described method of claim 1,14 or 15, wherein, this method also comprises the described step (2) that the product that step (7) obtains replaces step (5) with the lye that regenerates contacts and obtains A part of the desulfurized heavy fraction. 17. The method according to claim 1, wherein the gasoline is selected from one or more of catalytic cracking gasoline, catalytic cracking gasoline, straight run gasoline, coker gasoline, pyrolysis gasoline and thermal cracking gasoline.

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