JP6590835B2 - Method for producing gasoline with low sulfur and thiol content - Google Patents

Description

  The present invention relates to a method for producing gasoline having a low content of sulfur and thiol.

  The production of gasolines that meet new environmental standards requires that their sulfur content be substantially reduced.

  Converted gasoline, and more particularly that obtained from catalytic cracking, can represent 30-50% of the gasoline pool, which is known to have a high monoolefin and sulfur content. Yes.

  For this reason, about 90% of the sulfur present in gasoline is referred to as gasoline obtained from catalytic cracking processes (hereinafter referred to as FCC (fluid catalytic cracking) gasoline). Can be). FCC gasoline therefore constitutes a preferred feedstock for the process of the present invention.

  A possible route to the production of fuels with low sulfur content that has been used extensively consists of specifically treating sulfur-rich gasoline bases using catalytic hydrodesulfurization processes carried out in the presence of hydrogen. Traditional methods nondeselectively desulfurize gasoline by hydrogenating the majority of monoolefins, which causes a large drop in octane number and large hydrogen consumption. State-of-the-art methods, such as the Prime G + process (R), limit cracking of monoolefins and, as a result, cracked gasoline rich in olefins while limiting the resulting octane drop and high hydrogen consumption. Can be used to desulfurize. This type of method is described in, for example, patent applications 1 and 2, which are patent applications.

Residual sulfur-containing compounds generally present in desulfurized gasoline can be separated into two different groups: the reactor by a secondary reaction known as a recombination reaction with unconverted sulfur-containing compounds present in one feedstock. Sulfur-containing compounds formed in. In this latter family of sulfur-containing compounds, the main compound is a thiol obtained by addition of H ₂ S formed in the reactor to the monoolefin present in the feed. Thiols having the chemical formula R-SH (where R is an alkyl group), also known as recombined thiols, generally represent 20-80% by weight of residual sulfur in desulfurized gasoline.

  To obtain a gasoline with a very low sulfur content, typically less than 10 ppm by weight of sulfur as required in Europe, therefore removing at least some of the recombined thiols. Is required. This reduction in the amount of recombined thiol can be done by catalytic hydrodesulfurization, which involves the hydrogenation of the majority of monoolefins present in the gasoline, which results in a great reduction in the octane number of the gasoline as well as This leads to excessive consumption of hydrogen.

  To limit these disadvantages, various solutions have been described in the literature, hydrodesulfurization processes and recombined thiol removal by carefully selected techniques to avoid hydrogenation of existing monoolefins and maintain octane number. The cracked gasoline is desulfurized by combining the above processes (see Patent Documents 3 to 6).

European Patent Application Publication No. 1077247 (JP 2001-55584 A) European Patent Application No. 1174485 (Japanese Patent Laid-Open No. 2002-47497) US Patent No. 7799210 (Japanese Patent Laid-Open No. 2007-537332) US Pat. No. 6,960,291 (Japanese translations of PCT publication No. 2004-532928 gazette, Japanese translations of PCT publication No. 2004-531622 gazette, JP-T 2004-538346 gazette) US Pat. No. 6,387,249 US Patent Application Publication No. 2007/114156 (Japanese translations of PCT publication No. 2009-517499)

However, such a combination using a final step for the removal of recombined thiols is particularly suitable when very low sulfur content is required, while these can be used when the amount of thiol to be removed is high. It seems likely that it can be very expensive; for example, expensive adsorbent or solvent consumption is inevitable. This situation can occur especially when the acceptable thiol content in the gasoline pool is significantly lower than the total sulfur specification, which is the case in many countries, especially in Asia. Sulfur present in the fuel in the form of thiols or hydrogen sulfide (H ₂ S), in addition to causing toxicity and odor problems, can be associated with metallic and non-metallic materials present in the distribution system. Many can cause attacks. Therefore, almost all countries' specifications for thiols in fuel are very low (typically less than 10 ppm RSH) (measurement of thiol content using potentiometry (ASTM D 3227 method)), and total sulfur specifications. Is relatively high (for example, 50 to 500 ppm by weight). Other countries have adopted the “Doctor Test” measurement (ASTM D4952-12 method) to quantify thiols using negative specifications that must be met.

  Therefore, the most restrictive specification appears to be the specification of thiols rather than the total sulfur specification, as it is the most difficult to achieve without compromising the octane number in certain cases.

  One object of the present invention is a process for the treatment of gasoline containing sulfur, some of which are in the form of thiols, which limit the loss of octane as much as possible in conjunction with the consumption of reagents such as hydrogen or extraction solvents. While proposing a method that can be used to reduce the thiol content of the hydrocarbon fraction.

(Summary of Invention)
The present invention is a method for treating gasoline containing a sulfur-containing compound and an olefin, and includes at least the following steps:
a) contacting the gasoline, hydrogen and hydrodesulfurization catalyst in at least one reactor to convert at least a part of the sulfur-containing compound into H ₂ S, wherein the temperature is 200-400 The pressure is in the range of 0.5 to 5 MPa, the hourly space velocity is in the range of 0.5 to 20 h ⁻¹ , and the hydrogen is expressed in standard m ³ per hour. A step wherein the ratio between the flow rate and the flow rate of the feed to be treated, expressed in m ³ per hour under standard conditions, is in the range of 50 to 1000 Nm ³ / m ³ ;
b) separating H ₂ S formed and present in the effluent obtained from step a);
c) containing the effluent depleted in H ₂ S obtained from step b), deposited in a reactor with at least one transition metal or at least one sulfide of lead on a porous support The step of producing gasoline in contact with the catalyst to be used, the temperature at which step c) is performed is in the range of 30-250 ° C., and the liquid hourly space velocity is 0.5-10 h ⁻¹ . The pressure is in the range of 0.4-5 MPa, the ratio of H ₂ / feedstock is in the range of 0-25 Nm ³ of hydrogen per volume of feedstock (m ³ ), Including
The gasoline obtained from step c) provides a method having a reduced thiol content compared to the thiol content of the effluent obtained from step b).

  In fact, surprisingly, by using a catalyst and specific operating conditions downstream of the gasoline hydrodesulfurization reactor, thioethers of recombined thiols (generally less reactive compounds) by reaction with olefins It has been shown that sufficient conversion to a type of compound can result. Therefore, the dethiolation step c) (which may also be referred to as a non-desulfurization sweetening step) is for producing gasoline with a low thiol content specification without the need for harsh and expensive hydrodesulfurization finishing steps. Can be used.

  A further advantage of the process according to the invention is that it is greatly reduced in the final desulfurized gasoline due to the operating conditions for the hydrodesulfurization step (step a)) which is much less severe (eg a greater reduction in operating temperature and / or pressure) Resulting from the fact that it can be used to obtain low thiol content (eg less than 10 ppm by weight), which limits the loss of octane number and increases the lifetime of the catalyst for hydrodesulfurization processes Furthermore, it has the effect of reducing energy consumption.

  Preferably, the transition metal of the catalyst of step c) is selected from metals from group VIB, metals from group VIII and copper, which are used alone or as a mixture.

According to a preferred embodiment, the catalyst of step c) is
A carrier; constituted by gamma or delta alumina with a specific surface area in the range of 70-350 m ² / g;
An oxide of a metal from group VIB; an amount in the range of 1 to 30% by weight relative to the total catalyst weight;
An oxide of a metal from group VIII; an amount in the range from 1 to 30% by weight relative to the total catalyst weight;
Including
The sulfur content (%) of the constituent metals of the catalyst is at least 60%;
The molar ratio between the metal from group VIII and the metal from group VIB is in the range of 0.6-3 mol / mol.

  Preferably, the metal from Group VIII is nickel and the metal from Group VIB is molybdenum.

According to one embodiment, the catalyst of step c) is
A carrier; constituted only by gamma alumina having a specific surface area in the range of 180-270 m ² / g;
Nickel oxide; an amount by weight in the range of 4 to 12% by weight relative to the total catalyst weight;
Molybdenum oxide; including an amount by weight in the range of 6 to 18% by weight relative to the total catalyst weight;
The nickel / molybdenum molar ratio is in the range of 1 to 2.5 mol / mol;
The sulfidation rate (%) of the constituent metal of the catalyst is more than 80%.

The method of the present invention can be used to convert the effluent obtained from step b) to an LPG (liquefied petroleum gas) fraction, crude oil distillation, thermal cracking device, coking device, hydrocracking device, or oligomerization. may include a step of mixing gasoline fraction obtained from the device, and olefin C ₄ cut hydrocarbon fraction selected from for, the mixture is treated in step c). In a preferred variation in which the effluent obtained from step b) is treated as a mixture with the olefin C ₄ fraction, the effluent obtained from step c) is separated to separate the unreacted olefin C ₄ fraction. is bounded, the unreacted olefin C ₄ fraction is recycled to the reactor for step c). In this preferred embodiment, the effluent obtained from step b) is mixed with the olefin C ₄ fraction, the reaction for the addition of the thiol olefin is promoted in sweetened reactor. Advantageously, the effluent obtained from the sweetening step c) is fractionated so as to separate a fraction containing unreacted C ₄ olefin, said olefin C ₄ fraction being fed into the sweetening reactor Recirculated to

  Alternatively, prior to step a), a step for distillation of gasoline is performed, and the gasoline is fractionated into light and heavy gasoline fractions which are at least two gasoline fractions, The gasoline fraction is processed in steps a), b) and c).

  According to another embodiment, the effluent obtained from step b) is mixed with the light gasoline fraction obtained from distillation to form a mixture, which is processed in step c).

  In connection with the present invention, before step a), a step for distillation of gasoline is performed, and the gasoline is fractionated into at least two gasoline fractions, a light gasoline fraction and a heavy gasoline fraction. The heavy gasoline fraction is treated in step a) and the light gasoline fraction is mixed with the effluent from step a) to form a mixture, said mixture being in step b ) And c).

  Preferably, in the context of the above embodiment, the mixture with the light gasoline fraction contains up to 50% by volume of the light gasoline fraction.

According to another embodiment of the method, prior to step a), a step for distillation of gasoline is performed, wherein the gasoline is at least 3 gasoline fractions, respectively, a light gasoline fraction, an intermediate The gasoline fraction and the heavy gasoline fraction are fractionated and then the intermediate gasoline fraction is processed in step a) and then in steps b) and c). In this embodiment, the heavy gasoline fraction obtained from the distillation is advantageously processed in a dedicated apparatus in a hydrodesulfurization step, and then subjected to a step for thiol sweetening after removal of H ₂ S. It passes. The process for sweetening of the desulfurized heavy gasoline fraction is the same sweetening reactor as the one that processes the dedicated reactor or the intermediate gasoline fraction (the middle and heavy fractions are mixed as a sweetening reactor) May be performed at any time).

  Prior to step a) and prior to any optional distillation step, it is also possible to contact gasoline with hydrogen and a selective hydrogenation catalyst to selectively hydrogenate diolefins contained in said gasoline to olefins. is there. This step for the selective hydrogenation of diolefins may be carried out in a catalytic distillation column with a section containing a selective hydrogenation catalyst.

  In the context of the present invention, or alternatively, steps a) and / or c) may be carried out in a reactor which is a catalytic tower comprising at least one catalyst bed, in which at least the catalytic reaction and at least of gasoline. Both separations into two fractions (or fractions) are performed. When step a) is carried out in the catalyst tower, the fractions obtained from the catalyst tower are sent separately or as a mixture to steps b) and c) and their thiol content is reduced. According to another embodiment in which step a) is carried out in the catalyst column, only the light fraction is withdrawn from the head of the catalyst column that concentrates the thiol and sent to steps b) and c).

  According to a preferred embodiment, the process further comprises step d), in which the effluent obtained from step c) is sent to a fractionation tower where a gasoline fraction having a low thiol content is present. The hydrocarbon fraction containing the thioether compound is separated from the bottom of the fractionation tower.

  Advantageously, steps c) and d) are carried out continuously in a catalytic distillation column comprising a bed of catalyst for step c).

Preferably, the catalyst for step a) comprises at least one metal from group VIB and / or at least one metal from group VIII on a support having a specific surface area of less than 250 m ² / g. The amount of metal from Group VIII, expressed as an oxide, based on the weight of the catalyst contained, is in the range of 0.5 to 15% by weight, expressed as an oxide from Group VIB. The amount of metal is in the range of 1.5-60% by weight.

According to a preferred embodiment, the catalyst for step a) comprises cobalt and molybdenum, and the density of molybdenum, expressed as the ratio between the weight content of MoO ₃ and the specific surface area of the catalyst, is 7 × More than 10 ⁻⁴ g / m ² , preferably more than 12 × 10 ⁻⁴ g / m ² .

  Advantageously, step c) is carried out without adding hydrogen.

(Detailed description of the invention)
(Description of feedstock)
The present invention relates to a process for the treatment of gasoline containing any type of chemical family, in particular diolefins, monoolefins and sulfur-containing compounds. In particular, the present invention is applied to the conversion of converted gasoline, in particular gasoline derived from catalytic cracking, fluid catalytic cracking (FCC), coking, visbreaking or pyrolysis processes. By way of example, gasoline obtained from a catalytic cracker (FCC) averages 0.5 to 5 wt% diolefin, 20 to 50 wt% monoolefin and 10 wtppm to 0.5 wt% sulfur. Containing.

  The boiling point of the gasoline to be treated is generally below 350 ° C., preferably below 300 ° C. and very preferably below 220 ° C. The boiling point of the feedstock to which the method of the invention is applicable is in the range of 0-280 ° C, preferably in the range of 30-250 ° C. The feedstock may contain hydrocarbons containing 3 or 4 carbon atoms.

(Description of catalytic hydrodesulfurization step (step a))
The hydrodesulfurization step is performed to reduce the sulfur content of the gasoline to be treated, by converting the sulfur-containing compound to H ₂ S. The resulting H ₂ S is removed in step b). It is particularly necessary to do so when the feed to be desulfurized contains more than 100 ppm by weight of sulfur, more typically more than 50 ppm by weight of sulfur.

  The hydrodesulfurization step consists of contacting the gasoline to be treated with hydrogen in one or more hydrodesulfurization reactors containing one or more catalysts suitable for performing hydrodesulfurization.

  In a preferred embodiment of the invention, step a) is carried out for the purpose of performing selective hydrodesulfurization, i.e. the level of monoolefin hydrogenation is less than 80%, preferably less than 70%, Preferably it is less than 60%.

  The pressure when this step is performed is generally in the range of 0.5 to 5 MPa, preferably in the range of 1 to 3 MPa. The temperature is generally in the range of 200 to 400 ° C, preferably in the range of 220 to 380 ° C. When hydrodesulfurization step a) is carried out in a plurality of reactors in series, the average temperature at which each reactor is operated is generally at least 5 ° C., preferably at least 10 ° C., highly preferred. Is higher than the operating temperature of the preceding reactor by a minimum of 30 ° C.

The amount of catalyst employed in each reactor is represented by hourly volume under standard conditions (m ^3), the ratio between the volumetric flow and the catalyst of a gasoline to be treated (m ³⁾ (per hour it is also known) as space velocity is generally in the range of 0.5～20H ^-1, and preferably to a range of 1~15h ^-1. Highly preferably, the hydrodesulfurization reactor is operated at an hourly space velocity in the range of 2-8 h ⁻¹ .

The flow rate of hydrogen is the feed rate to be treated, expressed as the flow rate of hydrogen expressed in standard volumes per hour (m ³ ) (Nm ³ / h) and the volume per hour under standard conditions (m ³ ). the ratio between the flow rate is generally in the range of 50-1000 nm ³ / ^{m 3} is preferably as in the range of 70~800Nm ³ / ^{m 3.}

  The desulfurization level depends on the sulfur content of the feed to be treated, which is generally greater than 50%, preferably greater than 70%, so that the product obtained from step a) The product contains less than 100 ppm by weight of sulfur, preferably less than 50 ppm by weight of sulfur.

  In any case of a linked catalyst, the process includes a continuous hydrodesulfurization step, and as taught in document EP 1 612 255, the activity of the catalyst in step n + 1 is the activity of the catalyst in step n. It is in the range of 1 to 90%.

Any catalyst known to those skilled in the art and capable of promoting the reaction for the conversion of organic sulfur to H ₂ S in the presence of hydrogen may be used in connection with the present invention. However, in certain embodiments of the invention, a catalyst is preferably used that has good selectivity for the hydrodesulfurization reaction compared to the olefin hydrogenation reaction.

  Preferably, the hydrodesulfurization catalyst of step a) generally contains on the support at least one metal from group VIB and / or at least one metal from group VIII (CAS classification). Groups VIB and VIII are the IUPAC classification Groups 6 and 8-10 in the CRC Handbook of Chemistry and Physics (Editor-in-Chief DR Lide, 81st Edition, 2000-2001) published by CRC Publishing, respectively. Corresponding to metal from). The metal from group VIB is preferably molybdenum or tungsten, and the metal from group VIII is preferably selected from nickel and cobalt. In a highly preferred embodiment, the catalyst of step a) comprises cobalt and molybdenum.

  The amount of metal from group VIII, expressed as an oxide, is generally in the range 0.5 to 15% by weight, preferably in the range 1 to 10% by weight, based on the total catalyst weight. . The amount of metal from Group VIB is generally in the range of 1.5-60% by weight, preferably in the range of 3-50% by weight, based on the total catalyst weight.

  The catalyst support is usually a porous solid, such as alumina, silica-alumina, magnesia, silica or titanium oxide, which are used alone or as a mixture. Highly preferably, the support consists essentially of transition alumina, that is, it is at least 51% by weight, preferably at least 60% by weight, very preferably at least 80% by weight, based on the total weight of the support, or even Contains a minimum of 90% by weight transition alumina. It may in some cases be composed solely of transition alumina.

The specific surface area of the hydrodesulfurization catalyst is preferably less than 250 m ² / g, more preferably less than 230 m ² / g, and most preferably less than 190 m ² / g.

Molybdenum containing molybdenum alone or as a mixture with nickel or cobalt and expressed as a ratio between the weight content of MoO ₃ and the specific surface area of the catalyst to minimize olefin hydrogenation It is advantageous to use a catalyst having a density of greater than 7 × 10 ⁻⁴ g / m ² , preferably greater than 12 × 10 ⁻⁴ g / m ² . Highly preferably, the density of molybdenum comprising cobalt and molybdenum, expressed as a ratio between the amount by weight of MoO ₃ and the specific surface area of the catalyst, is greater than 7 × 10 ⁻⁴ g / m ² , preferably 12 × A catalyst that is greater than 10 ⁻⁴ g / m ² is selected.

  Advantageously, prior to sulfiding, the average pore size of the hydrodesulfurization catalyst is greater than 20 nm, preferably greater than 25 nm, even greater than 30 nm, often in the range of 20-140 nm, preferably in the range of 20-100 nm. Most preferably, it is in the range of 25-80 nm. The pore size is measured by a mercury porosimetry according to ASTM D4284-92 with a wetting angle of 140 °.

  The metal is deposited on the support using any method known to those skilled in the art, for example, dry impregnation of a solution containing a precursor of the metal, or overimpregnation. The solution is selected so that the metal precursor can be dissolved at a desired concentration. For example, for the synthesis of a CoMo catalyst, the molybdenum precursor may be molybdenum oxide or ammonium heptamolybdate. Examples that may be mentioned for cobalt are cobalt nitrate, cobalt hydroxide and cobalt carbonate. The precursors are generally dissolved in a medium that can dissolve them at the desired concentration. It can therefore be an aqueous and / or organic medium depending on the case.

  After the introduction of one or more metals and optionally shaping the catalyst, the catalyst is activated in a first step. This activation may correspond to either firing (oxidation) and subsequent reduction, or direct reduction, or only firing. The firing step is generally performed in a stream of air at a temperature in the range of 100 to 600 ° C., preferably 200 to 450 ° C. The reduction step is performed under conditions that allow at least a portion of the base metal in oxide form to be converted to metal. In general, it consists of treating the catalyst in a hydrogen stream, preferably at a temperature which is at least 300 ° C.

The catalyst is preferably used at least partially in its sulfurized form. Sulfur may be introduced before or after any activation step, ie calcination or reduction. Preferably, no step for oxidation of the catalyst is performed when sulfur or a sulfur-containing compound is introduced onto the catalyst. Sulfur or sulfur-containing compounds are used ex situ, i.e. outside the reactor in which the process of the invention is carried out, or in situ, i.e. for the process of the invention. It may be introduced in the reactor. In this latter case, the catalyst is preferably at least one sulfur-containing compound that, once decomposed, is sulfided by passage of a feed containing it that leads to fixing of sulfur on the catalyst. . This feedstock may be a gas or a liquid, for example a hydrogen containing H ₂ S or a liquid containing at least one sulfur-containing compound.

  Preferably, the sulfur-containing compound is added to the catalyst off-site. As an example, after the calcination step, the sulfur-containing compound may be introduced onto the catalyst, optionally in the presence of another compound. The catalyst is then dried and then transferred to a reactor that serves to carry out the process of the invention. In this reactor, the catalyst is then treated in hydrogen to convert at least a portion of the main metal to sulfide. Particularly suitable procedures for sulfiding the catalyst are those described in the documents FR 2 708 596 and FR 2 708 597.

  In an alternative embodiment, step a) is carried out in a catalytic distillation column with a section comprising a hydrodesulfurization catalyst, in which at least two fractions (or fractions) of catalytic hydrodesulfurization reaction and gasoline. Both separations are performed. Preferably, the catalytic distillation column comprises two beds of hydrodesulfurization catalyst and the feed is sent between the two beds of column catalyst.

(Step for separating hydrogen and H ₂ S (step b)))
This step is performed in order to separate the excess hydrogen and H ₂ S formed during step a) from the effluent obtained from step a). Any method known to those skilled in the art may be envisaged.

According to a first preferred embodiment, after hydrodesulfurization step a), the effluent is cooled to a temperature generally below 80 ° C., preferably below 60 ° C., and the hydrocarbons are condensed. The gas phase and liquid phase are then separated in a separation drum. The liquid fraction containing desulfurized gasoline as well as some dissolved H ₂ S is sent to the stabilization tower, ie the debutane tower. This tower separates the top and bottom fractions. The top fraction is essentially composed of residual H ₂ S and a hydrocarbon compound having a boiling point that is below the boiling point of butane, the bottom fraction is free of H ₂ S and is referred to as stabilized gasoline, Contains compounds having a boiling point higher than that of butane.

In a second preferred embodiment, after the condensation step, the desulfurized gasoline and the liquid fraction containing some dissolved H ₂ S are sent to the stripping section, while the gas mainly composed of hydrogen and H ₂ S. The fraction is sent to the purification section. Stripping may be performed by heating the hydrocarbon fraction in a distillation column, alone or with hydrogen or steam injection, to extract the light compounds at the top of the column as well as residual dissolved H ₂ S. The light compounds at the top of the column are entrained by dissolving in the liquid fraction. The temperature of the stripped gasoline recovered from the bottom of the column is generally in the range of 120 to 250 ° C.

Step b) preferably has sulfur in the form of H ₂ S remaining in the desulfurized gasoline prior to step c) of dethiolation (sweetening) present in the hydrocarbon fraction to be treated. It is carried out to show less than 30%, preferably less than 20%, more preferably less than 10% of the total sulfur.

Step for catalytic sweetening of the desulfurized hydrocarbon fraction obtained from (step b) (step c))
This step consists of converting the sulfur-containing compound from the thiol group into a heavier thioether-type sulfur-containing compound. These thiols are essentially recombined thiols resulting from the reaction of H ₂ S formed in step a) with gasoline olefins.

The conversion reaction employed in this step c) consists of reacting the thiol with an olefin to form a heavier sulfur-containing compound of the thioether type. It should be noted that this process must be distinguished from a “conventional” hydrodesulfurization process aimed at converting sulfur-containing compounds to H ₂ S in the presence of hydrogen.

This step can also be used to convert residual H ₂ S to thioether that was not completely removed during step b) by reaction with olefins present in the feed.

  The dethiolation (or sweetening) reaction is performed with a catalyst containing at least one transition metal or at least one sulfide of lead deposited on a porous support. This reaction is preferably carried out with a catalyst comprising at least one sulfide of a metal selected from Group VIB, Group VIII, copper and lead.

  Most preferably, the catalyst comprises at least one element from Group VIII (Groups 8, 9 and 10 of the Periodic Classification of Elements of the Handbook of Chemistry and Physics, 76th Edition, 1995-1996), Group VIB ( At least one element and carrier from the group 6 of the Periodic Classification of Elements of the Handbook of Chemistry and Physics, 76th edition, 1995-1996). The element from group VIII is preferably selected from nickel and cobalt, but in particular nickel. The element from group VIB is preferably selected from molybdenum and tungsten, most preferably molybdenum.

The catalyst support for step c) is preferably selected from alumina, nickel aluminate, silica, silicon carbide, or a mixture of these oxides. Alumina is preferably used, and high purity alumina is more preferable. Preferably, a support is used whose total pore volume measured by mercury porosimetry is in the range of 0.4 to 1.4 cm ³ / g, preferably in the range of 0.5 to 1.3 cm ³ / g. The specific surface area of the support is preferably in the range of 70 to 350 m ² / g.

  In a preferred variation, the support is cubic gamma alumina or delta alumina.

The catalyst employed in step c) is preferably
A carrier; constituted by gamma or delta alumina with a specific surface area in the range of 70-350 m ² / g;
An oxide of a metal from group VIB; an amount in the range of 1 to 30% by weight relative to the total catalyst weight;
An oxide of a metal from group VIII; an amount in the range from 1 to 30% by weight relative to the total catalyst weight;
Including
The sulfur content (%) of the constituent metals of the catalyst is at least 60%;
The molar ratio between the metal from group VIII and the metal from group VIB is in the range of 0.6-3 mol / mol.

In particular, it has been discovered that performance is improved when the catalyst for step c) has the following characteristics:
The support is constituted by gamma alumina having a specific surface area in the range of 180 to 270 m ² / g;
The amount by weight of the oxide of the element from group VIB in the form of an oxide is in the range from 4 to 20% by weight, preferably in the range from 6 to 18% by weight, based on the total catalyst weight ;
The amount of metal oxide from group VIII, expressed in oxide form, is in the range from 3 to 15% by weight, preferably in the range from 4 to 12% by weight, based on the total catalyst weight;
The molar ratio between the non-noble metal from group VIII and the metal of group VIB is in the range of 0.6-3 mol / mol, preferably in the range of 1-2.5 mol / mol;
The sulfidation rate (%) of the constituent metal of the catalyst is at least 60%.

In a highly preferred embodiment of the invention, the catalyst employed in step c) is a nickel oxide (in the form of NiO) in an amount by weight in the range of 4-12%, based on the total catalyst weight, and the total catalyst. Containing molybdenum oxide (in the form of MoO ₃ ) in an amount by weight in the range of 6 to 18% by weight, the molar ratio of nickel / molybdenum being in the range of 1 to 2.5 The metal is deposited on a support composed only of gamma alumina having a specific surface area in the range of 180 to 270 m ² / g, and the sulfidity of the metal constituting the catalyst is more than 80%.

  The catalyst for step c) may be prepared using any technique known to those skilled in the art, in particular by impregnation of the metal on the selected support.

  After introducing the metal and possibly shaping the catalyst, it undergoes an activation process. This treatment is generally aimed at converting the molecular precursor of the element into an oxide phase. In this case, it is an oxidation treatment, but simple drying of the catalyst may be performed. In the case of an oxidation treatment, also known as calcination, this is generally carried out in air or diluted oxygen and the treatment temperature is generally in the range of 200 to 550 ° C., preferably 300 to 500 ° C. Is within the range.

After calcination, the metal deposited on the support is in the form of an oxide. In the case of nickel and molybdenum, the metal is mainly in the form of MoO ₃ and NiO. Prior to contact with the feed to be treated, the catalyst undergoes a sulfidation step. Sulfurization is preferably carried out in a sulpho-reducing medium, ie in the presence of H ₂ S and hydrogen, and the metal oxide is converted to sulfides, eg MoS ₂ and Ni ₃ S ₂ . Is done. Sulfurization is performed by injecting a stream containing H ₂ S and hydrogen over the catalyst or a sulfur-containing compound that can be broken down to H ₂ S in the presence of the catalyst and hydrogen. Polysulfides, such as dimethyldisulphide (DMDS), are precursors of H ₂ S that are routinely used to sulfidize catalysts. The temperature is adjusted so that H ₂ S reacts with the metal oxide to form a metal sulfide. This sulfidation may be performed in-situ or off-site (inside or outside of the reactor) of the dethiolation reactor, with the temperature in the range of 200-600 ° C, more preferably 300-500 ° C. Is within the range.

Step c) for sweetening against thiols consists of contacting gasoline that has been desulfurized and does not contain at least some H ₂ S with a catalyst in the form of sulfides. The dethiolation reaction of the present invention is carried out through a direct addition on a double bond between a thiol and an olefin to give a compound of formula R ₁ —S—R ₂ , wherein R ₁ and R ₂ are alkyl groups Which have a boiling point that is higher than the boiling point of the starting thiol.

This sweetening step may be performed in the absence of hydrogen (without adding or replenishing hydrogen) or in the presence of hydrogen fed to the reactor. Preferably it is done without adding hydrogen. If hydrogen is used, it is injected with the feed to maintain the hydrogenated surface quality on the catalyst and be suitable for high conversion in dethiolation. Typically, the H ₂ / feed in operating step c) is in the range of 0-25 Nm ³ hydrogen per volume of feed (m ³ ), preferably hydrogen per volume of feed (m ³ ). in the range of 0 to 10 nm ^3, highly preferably in the range of volume ^{(m 3)} of hydrogen per 0 to 5 nm ³ of feedstock, more preferably in the range of the volume of feed ^{(m 3)} of hydrogen per 0～2Nm ³ is there.

  The entire feedstock is generally injected into the reactor inlet. However, in some cases it may be advantageous to inject some or all of the feedstock between two successive catalyst beds disposed in the reactor.

The temperature at which the gasoline to be treated is brought into contact with the catalyst is in the range of 30 to 250 ° C., preferably in the range of 60 to 220 ° C., more preferably in the range of 90 to 200 ° C., and the liquid per hour The liquid hourly space velocity (LHSV) is in the range of 0.5 to 10 h ⁻¹ and the unit of liquid hourly space velocity is the volume of feedstock (liters) per hour and per volume of catalyst (liters). ) (L / L · h). The pressure is in the range of 0.2-5 MPa, preferably in the range of 0.5-2 MPa, and more preferably in the range of 0.6-1 MPa.

  During this step c), the thiol combined with the feed olefin to form the thioether compound typically contains 5 to 12 carbon atoms, more commonly branched. Yes. By way of example, thiols that may be included in the feed for step c) are 2-methylhexane-2-thiol, 4-methylheptane-4-thiol, 2-ethylhexane-3-thiol or 2,2 , 4-trimethylpentane-4-thiol.

  At the end of step c), the thiol content of the hydrocarbon fraction treated under the above conditions has therefore been reduced (these thiols have been converted into thioether compounds). Generally, the gasoline produced at the end of step c) contains less than 20 ppm by weight, preferably less than 10 ppm by weight, and even more preferably less than 5 ppm by weight. During this step c), no replenishment of hydrogen is required and the olefin is not hydrogenated or only slightly hydrogenated, which means that the effluent octane number at the outlet from step c) Means that it can be kept high. Generally, olefin hydrogenation is less than 2%.

As Engineering for the fractionation of sweetening already gasoline obtained from (step c) (step d by case)))
At the end of step c), the thiol content of gasoline processed under the above conditions is therefore reduced. In fact, these thiols have been converted to thioether type compounds whose molecular weight is greater than the molecular weight of the starting thiol.

  According to the present invention, in some cases, a step (step d)) is performed for fractionating gasoline with thiol sweetening into at least one light and heavy fraction of hydrocarbons. . This fractionation step involves the heavy hydrocarbon fraction containing the thioether type sulfur-containing compound formed in step c) and the heaviest and most resistant residual thiols that did not react during step c). Under conditions such that it is concentrated in. Preferably, the fractionation step is carried out so that the light fraction of hydrocarbons with a low sulfur content, in particular a low content of thiols and sulfide compounds, has a final boiling point in the range of 130-160 ° C. Obviously, for those skilled in the art, it is possible to select the cut point (ie, the final boiling point for the light hydrocarbon fraction) depending on the sulfur content of the target in the light hydrocarbon fraction. Typically, the thiol content of the light gas fraction is less than 10 ppm by weight, preferably less than 5 ppm by weight, even more preferably less than 1 ppm by weight, and the total sulfur content is less than 50 ppm by weight, preferably Is less than 20 ppm by weight, even more preferably less than 10 ppm by weight. Light hydrocarbon fractions with low sulfur and thiol content are advantageously sent to the refinery gasoline pool. The heavy hydrocarbon fraction is enriched with sulfur-containing thioether type compounds and thiols that are resistant to addition reactions with olefins, which are advantageously more severe hydroprocessing Treated in hydrodesulfurization equipment applying conditions (higher temperature, greater amount of hydrogen used) or sent to refinery gas oil pool.

  The step for thiol sweetening (step c)) and the step for fractionation (step d)) may be carried out simultaneously using a catalyst tower with a catalyst bed containing the sweetening catalyst. It should be noted. Preferably, the catalytic distillation column comprises two beds of sweetening catalyst and the feed is sent between the two beds of catalyst in the column.

(Layout that can be adopted in connection with the present invention)
Various layouts may be employed to produce desulfurized gasoline with reduced thiol content at low cost. The choice of optimized layout depends on the circumstances of the gasoline characteristics to be processed and manufactured, as well as the constraints at each refinery.

  The layout described below is given by way of illustration and not limitation.

  In a first variation, the catalyst sweetening step c) may be performed directly in series with the separation step b). In particular, if the separation step b) is performed at a temperature that matches the temperature at which the catalyst sweetening step c) is performed, the effluent obtained from step b) is sent directly to step c). It may be envisaged that the temperature between steps b) and c) may be adjusted using heat exchange equipment.

In a second variation, before the catalyst sweetening step c), the gasoline obtained from step b) is an LPG (liquefied petroleum gas) fraction or another gasoline fraction containing sulfur, for example a distillation of crude oil. Mixed with gasoline from any cracking method, such as gasoline obtained from a pyrolysis, coking or hydrocracking process, or gasoline obtained from an oligomerization unit, The mixture is processed in step c). In order to promote the catalytic addition reaction (recombination) of thiols and olefins in the sweetening step c), the gasoline obtained from step b) can also be mixed with the olefin C ₄ hydrocarbon fraction and processed. is there.

In a third variation, the process for distillation of the gasoline to be treated is carried out to separate two fractions (or fractions), namely a light fraction and a heavy fraction, Are processed by the method of the present invention. Therefore, in the first embodiment, the heavy fraction is treated by hydrodesulfurization (step a)) and then the formed H ₂ S present in the heavy hydrodesulfurization fraction is removed. (Step b)), then the light fraction (obtained from distillation) is mixed with the heavy fraction obtained from step b) and finally the mixture is processed in step c). Alternatively, in a second embodiment within the third variation, the light fraction is mixed with the heavy hydrodesulfurization fraction obtained from step a) and this resulting mixture is mixed with steps b) and processed in c). The advantage of this third variation is that it does not hydrotreat light fractions rich in olefins and generally depleted of sulfur, which means that the octane number due to olefin hydrogenation is not hydrotreated. It means that loss can be limited. Preferably, in this third variation, the feedstock treated in step c) is constituted by all heavy desulfurization fractions and some light fractions in the range of 0-50% by volume. In connection with this third variation, the boiling range of the light fraction is less than 100 ° C and the temperature range of the heavy fraction is above 65 ° C.

In a fourth variation, gasoline is distilled into two fractions: a first light fraction and a first heavy hydrocarbon fraction. The boiling point of the first light fraction is in the range between the initial boiling point of the gasoline to be treated and the final boiling point located between 140 ° C and 160 ° C. The first light hydrocarbon fraction is then treated by hydrodesulfurization (step a)), and the formed H ₂ S is then separated from the hydrodesulfurization effluent (step b)) and hydrogenated. The thiol in the desulfurization effluent is sweetened (step c)), the thiol sweetened effluent is fractionated (step d)), and a second light gasoline fraction (the initial of the gasoline to be treated). A boiling point in the range between the boiling point and the final boiling point of 140 ° C. or less) and a second heavy hydrocarbon fraction. The thiol and thioether content of the second light gasoline fraction is low, and the second heavy hydrocarbon fraction contains unconverted thioether and thiol. In some cases, the first and second heavy hydrocarbon fractions may be mixed and processed by hydrodesulfurization in a dedicated apparatus.

In a fifth variation, gasoline is distilled into light, intermediate and heavy fractions, three hydrocarbon fractions, using one or more distillation columns. The boiling point of the light hydrocarbon fraction is preferably in the range from the initial boiling point of the gasoline to be treated to the final boiling point between 50 ° C and 90 ° C. This type of light hydrocarbon fraction generally contains little sulfur and can therefore be upgraded directly to refinery gasoline pools. An intermediate hydrocarbon fraction having a boiling range generally in the range from 50 ° C. to 140 ° C. or 160 ° C. is treated by hydrodesulfurization (step a)), and then the formed H ₂ S is hydrogenated. Separated from the hydrodesulfurization effluent (step b)), the hydrodesulfurization effluent is subjected to thiol sweetening (step c)), and the thiol sweetened effluent is fractionated (step d)), A second intermediate gasoline fraction having a low thiol and thioether content and a second heavy hydrocarbon fraction containing unconverted thioether and thiol are produced. In some cases, the first and second heavy hydrocarbon fractions may be mixed and processed by hydrodesulfurization in a dedicated apparatus.

In a sixth variation, the gasoline to be treated first undergoes a preliminary process consisting of the selective hydrogenation of diolefins present in the feedstock, as described in patent application EP 1 077 247. The selectively hydrogenated gasoline is then distilled into at least two hydrocarbon fractions or three hydrocarbon fractions: a light fraction, a middle fraction and a heavy fraction. In the case of fractionation into two hydrocarbon fractions, the above steps for the third and fourth variations are applicable. In the case of fractionation into three hydrocarbon fractions, the middle fraction is separated separately from the hydrodesulfurization step (step a)), then the step for separating H ₂ S (step b)), then In the sweetening step (step c)). In some cases, the effluent obtained from step c) is subjected to fractionation step d) to a second intermediate gasoline fraction having a low thiol and thioether content and a second containing an unconverted thioether and thiol. Heavy hydrocarbon fraction. In some cases, the second heavy hydrocarbon fraction is mixed with the heavy fraction obtained from distillation upstream of the hydrodesulfurization process, and this mixture is processed by hydrodesulfurization in a dedicated apparatus.

  It should be noted that it is possible to carry out the diolefin hydrogenation and fractionation into two or three fractions simultaneously using a catalytic distillation column including a distillation column with a catalyst bed.

  In a seventh variation, step a) is performed in a catalytic distillation column. This catalytic distillation tower incorporates a hydrodesulfurization catalyst bed, both desulfurizing gasoline and separating two hydrocarbon fractions, light and heavy fractions. Can do. The resulting fractions are then sent to steps b) and c) separately or as a mixture. Alternatively, only the light gasoline fraction obtained from the catalytic distillation column for hydrodesulfurization is treated in step b) and then in step c). In this case, the effluent from step c) may be fractionated into two hydrocarbon fractions according to step d) above. Again, in this case, the heavy fraction obtained from the catalytic distillation column for hydrodesulfurization is obtained in the second hydrodesulfurization unit alone or light gasoline obtained from the catalytic distillation column for hydrodesulfurization. It may be treated as a mixture with the heavy fraction obtained from step d) for fractionation.

In order to improve the conversion (recombination) of thiols into thioethers during step c), if step c) is carried out on the light fraction, the mixture of olefin C ₄ fraction and light gasoline is advantageously is caused upstream of step c), step c) is advantageously not only light fraction is performed for mixtures containing light hydrocarbon fraction to olefin C ₄ fraction. At the end of step c), the thiol sweetened effluent is sent to a separation column, which separates the olefin C ₄ fraction and the thiol sweetened light fraction. Olefin C ₄ fraction withdrawn from the separation column are advantageously recycled to the reactor for step c).

  In order to improve the conversion (recombination) of thiols into thioethers during step c), if step c) is carried out on middle or heavy fractions, all or part of the light gasoline is advantageously Is added to the intermediate or heavy fraction upstream of step c) so that step c) is advantageously carried out on the mixture containing the olefins fed by the light hydrocarbon fraction.

  Of all the possible variations, the following two variations are preferred.

1. The gasoline is distilled into two fractions (or fractions), a light fraction (or fraction) and a heavy fraction (or fraction), with only the heavy fraction being hydrodesulfurized steps a) and H _2. Treated in step b) for separating S, desulfurized gasoline is stabilized. After optionally adjusting the temperature between steps b) and c) using a heat exchange device, the stabilized heavy fraction is then processed in the sweetening step c) in the absence of hydrogen. The advantage of this particular mode of operation is that it produces gasoline that does not require further processing before the thiol is sweetened and sent to the gas pool while limiting the required investment as much as possible.

2. The gasoline is distilled into two fractions, a light fraction (or fraction) and a heavy fraction (fraction), and only the heavy fraction is subjected to hydrodesulfurization step a) and H ₂ S. Treated in step b) for separation, the desulfurized gasoline is stabilized or simply free of H ₂ S by stripping. The feedstock treated in step c) with or without the addition of hydrogen contains all of the desulfurized heavy fraction and some light fraction within the range of 10-50% by volume. The effluent obtained from step c) is then stabilized in a step similar to step b). The advantage of this particular mode of operation lies in maximizing thiol conversion during step c) by using an olefin-rich light fraction to favor thiol over thioether conversion reactions.

Further features and advantages of the present invention will become apparent from the following description, given by way of non-limiting illustration only, reference being made to the accompanying drawings, in which:
FIG. 1 is a layout of a method according to a first embodiment according to the present invention;
FIG. 2 is a layout of a method according to a second embodiment according to the present invention;
FIG. 3 shows the layout of an alternative method according to the third embodiment;
FIG. 4 shows a fourth embodiment of the method of the present invention.

  In the drawings, similar elements are generally designated by the same reference numeral.

Referring to FIG. 1, in the first embodiment of the method of the present invention, the gasoline to be treated passes through the line (1) and the hydrogen passes through the line (3) to the hydrodesulfurization unit (2). Sent. The gasoline to be treated is generally cracked gasoline, preferably catalytic cracked gasoline. Gasoline is characterized by a boiling point that is typically in the range of 30-220 ° C. By way of example, the hydrodesulfurization unit (2) is a reactor containing a fixed bed or fluidized bed desulfurization catalyst (HDS); preferably a fixed bed reactor is used. The reactor is operated in the presence of an HDS catalyst under the operating conditions described above to decompose sulfur-containing compounds and form hydrogen sulfide (H ₂ S). Hence, the effluent (gasoline) containing H ₂ S is withdrawn from the hydrodesulfurization reactor (2) via line (4). Next, the effluent undergoes an H ₂ S removal step (step b)). This, in the embodiment of FIG. 1, consists in treating the effluents in stabilization column (5), C ₄ via the line (6) at the top of the column ^- the majority and non-hydrocarbons, H 2 _S The stream containing the reaction hydrogen is separated from the gasoline known as stabilized gasoline from the bottom of the column.

Stabilized gasoline is sent to sweetening reactor (8) via line (7) to reduce the amount of thiol in the stabilized gasoline (step c)). The thiols contained in this stabilized gasoline are mainly recombined thiols obtained from the reaction of H ₂ S on olefins. As discussed above, the sweetening reactor employs a catalyst that can cause the addition reaction of thiols on olefins via direct addition across double bonds to yield thioether type compounds. . This thioether type compound has the formula R ₁ —S—R ₂ , where R ₁ and R ₂ are alkyl groups, and has a molecular weight greater than the molecular weight of the starting thiol. The reaction for catalytic conversion of the thiol may optionally be carried out in the presence of hydrogen, which is fed via line (9).

  As indicated in FIG. 1, stabilized and thiol sweetened gasoline is withdrawn from the reactor (8) via line (10), which is advantageously separated from the separation column ( 11). This separation tower (11) is designed and operated to overhead-stabilize stabilized light gasoline via line (12). The boiling range of this stabilized light gasoline is preferably in the range of 30-160 ° C or in the range of 30-140 ° C, and the total content of thiol and sulfur is less than 10 ppm by weight and less than 50 ppm by weight, respectively. It is. At the bottom of the separation column (11), heavy gasoline is recovered via line (13), which contains the thioether type compound formed in the sweetening reactor (8). Light gasoline is sent to the gasoline pool, while heavy gasoline is either hydrodesulfurized in a dedicated hydrotreater or sent to a refinery diesel pool or distillate boule. is there.

FIG. 2 shows a second embodiment. The second embodiment is based on the embodiment of FIG. 1, but the olefinic hydrocarbon fraction in which the stabilized gasoline is fed in the thiol sweetening reactor (8) via line (14), preferably It differs in the fact that it is processed in the presence of the olefin C ₄ fraction. The purpose of adding this olefin fraction is to favor the addition reaction of thiols with olefins by supplying active olefins to the reaction medium. As indicated in FIG. 2, the effluent obtained from the sweetening reactor is sent to a separation tower (15) where a portion of the olefin fraction that has not reacted in the sweetening reactor (8). Collected. If the olefin fraction is a C ₄ fraction, the separation tower (15) employed corresponds to a debutane tower, which separates the C ₄ fraction from the head of the tower (15) It is recycled to the sweetening reactor (8) via (16). The fraction (17) recovered from the bottom of the column (15) is fractionated in the column (11) as described in connection with FIG. 1, and is low in sulfur and thiol via line (12). A quantity of light gasoline fraction and a heavy gasoline fraction containing the thioether compound formed in the sweetening reactor (8) are provided.

  FIG. 3 illustrates a third embodiment of the method of the present invention. The gasoline feed to be treated typically contains hydrocarbons boiling between 30 ° C. and 220 ° C., which are first sent to the distillation column (20). The distillation column (20) is configured to fractionate the gasoline feedstock into three fractions. An overhead fraction containing a compound lighter than butane and containing butane is withdrawn via line (21). A middle distillate containing hydrocarbons containing 6-7 or 6-8 carbon atoms is recovered via line (22). Finally, the bottom fraction constituted by hydrocarbons containing 7 or more than 8 carbon atoms is withdrawn via line (23).

  It should also be noted that before fractionation, the gasoline feed is advantageously pre-treated in a reactor (19) for selective hydrogenation of diolefins to olefins. This catalytic reaction is preferably operated under conditions and in the presence of a catalyst as described in the documents EP 1 445 299 or EP 1 800 750.

Referring to FIG. 3, the bottom fraction is treated as described above in the hydrodesulfurization reactor (24) in the presence of hydrogen (supplied via line (25)) and hydrodesulfurization catalyst. . The desulfurization effluent is withdrawn from the reactor (24) via line (26) and sent to an H ₂ S separator (27) such as a stripping tower from which H ₂ S and hydrogen are essentially removed. The gas fraction contained in is separated via line (28) and the bottom fraction having a low sulfur content is separated via line (29).

As indicated in FIG. 3, the intermediate gasoline fraction is processed using the method of the present invention. The intermediate gasoline fraction is therefore sent via line (22) to the hydrodesulfurization reactor (2) where it is desulfurized in the presence of hydrogen fed via line (3). The effluent obtained from the reactor (2) does not contain H ₂ S formed during the HDS process in the separator (5). Intermediate gasoline depleted in H ₂ S is sent to the thiol sweetening reactor (8) via line (7) and possibly with hydrogen supplied via line (9). In order to improve the conversion of thiol to thioether compound by addition on the olefin, the light olefin compound contained in the overhead fraction (21) is fed to the sweetening reactor (8) via line (34). It is possible to supply. The intermediate gasoline fraction subjected to thiol sweetening is sent to the fractionation tower (11) via the line (10), and this fractionation tower (11) is an intermediate with a low content of thiol and sulfur. It is operated to separate the gasoline fraction from the middle bottom fraction enriched in the thioether compound produced during the sweetening process. The middle gasoline fraction with low thiol and sulfur content is discharged to the refinery gasoline pool via line (12), while the middle bottom fraction discharged via line (13) It is either desulfurized in a hydrotreating device (eg, gas oil hydrodesulfurization device) or sent directly to a refinery gas oil pool. As shown also in FIG. 3, it is possible to stabilize the hydrocarbon effluent obtained from the sweetening reactor (8) in the stabilization tower (or debutane tower) (31) by treating it. From the stabilization column (31), a light hydrocarbon fraction containing up to 4 carbon atoms is separated from the top, and a stabilized intermediate gasoline fraction with thiol sweetening is separated from the bottom. , And sent to the fractionation tower (11) via the line (33). Advantageously, the middle bottom fraction (13) is mixed with the bottom fraction (23) obtained from the first fractionation step carried out in the column (20) in the hydrodesulfurization reactor (24). As may be desulfurized.

  FIG. 4 discloses a fourth embodiment of the process of the invention using a catalytic distillation column.

A gasoline feed, for example a hydrocarbon fraction boiling between 30 ° C. and 220 ° C., or between 30 ° C. and 160 ° C., and even between 30 ° C. and 140 ° C., is passed via line (1), It is sent to the first catalytic distillation column (40). This first catalytic distillation column (40) includes a reaction section (41) containing a selective diolefin hydrogenation catalyst. The hydrogen required to carry out the hydrogenation reaction is supplied via line (2). The mode of operation of the catalyst column (40) is not only capable of performing a selective catalytic hydrogenation reaction, but also to a light hydrocarbon fraction at the top of the column and a heavy hydrocarbon fraction at the bottom of the column (40). Means that fractionation can be performed. Therefore, the light hydrocarbon fraction mixed with unreacted hydrogen is withdrawn via line (42) and the heavy hydrocarbon fraction is withdrawn via line (43). Light fraction, for example, _{C 4} ^- a fraction, the heavy hydrocarbon fraction _is in the range of (C 5 -220 ℃) or _(C 5 -160 ℃) or _(C 5 -140 ℃) It is a boiling fraction.

The heavy hydrocarbon fraction is then treated according to the method of the present invention, which in this embodiment is hydrogen carried out in a catalytic distillation column (45) comprising two beds (46) of hydrodesulfurization catalyst. It consists of a hydrodesulfurization process. Preferably, the heavy hydrocarbon fraction is injected between the two beds (46) of the hydrodesulfurization catalyst along with hydrogen (via line (44)). Catalytic distillation tower (45) also a heavy hydrocarbon _fraction, (C 5 -140 ° C.) or _(C 5 -160 ° C.) the intermediate overhead fraction boiling in the range of, respectively 140 ° C. or greater than Allowing fractionation to a bottom fraction having a boiling point above 160 ° C. According to the present invention, in order to reduce the amount of thiols in the middle distillate, this middle distillate is discharged via line (47) and the removal of H ₂ S using the stabilization column (5). Through the process, the tower top stream containing the majority of H ₂ S from the tower via line (6) and the stabilized middle distillate from line bottom via line (7) are separated. The This stabilized middle distillate is processed in the sweetening reactor (8). The thiol sweetened middle distillate obtained from the reactor (8) is then fractionated in the column (11) via line (10) and has a sulfur, thiol and thioether content. Low gasoline is recovered overhead (via line (12)). The _gasoline boiling in the range of (C 5 -140 ℃) or _(C 5 -160 ℃). The bottom fraction contains sulfide, which typically contains at least 10 carbon atoms and results more from the addition reaction of thiols to olefins, and the bottom fraction is from the column (11). It is extracted from the bottom via a line (13). In some cases, as indicated in FIG. 4, the middle distillate is obtained in the sweetening reactor (8) from light hydrocarbons obtained from the head of the catalytic distillation column (40) via line (49). Treated as a mixture with fractions.

As shown in FIG. 4, the middle distillate obtained from the reactor (8) and sweetened with thiol may be subjected to a stabilization step performed in the stabilization tower (31) in some cases. From here, the C ₄ ^- fraction and the intermediate stabilized fraction with thiol sweetening are extracted from the head and bottom of the column (31), respectively. The stabilized middle distillate with thiol sweetening is then sent to the fractionation tower (11) via line (33).

  It should be noted that the thiol sweetening step and the fractionation step can be performed simultaneously using a catalyst tower with a catalyst bed containing a sweetening catalyst.

(Example 1: Comparison)
Hydrodesulfurization catalyst A has a specific surface area of 130 m ² / g and a pore volume of 0.9 mL / g, transition alumina in the form of beads, and ammonium heptamolybdate and cobalt nitrate, respectively. It was obtained by impregnating an aqueous solution containing molybdenum and cobalt with a “non-excess solution”. The catalyst was then dried and calcined at 500 ° C. in air. The contents of cobalt and molybdenum in each sample were 3% by weight of CoO and 10% by weight of MoO ₃ .

  50 mL of Catalyst A was placed in a tubular fixed bed hydrodesulfurization reactor. The catalyst was first sulfided by treatment for 4 hours in contact with a feedstock constituted by 2% by weight of sulfur in the form of dimethyldisulfide in n-heptane at a pressure of 3.4 MPa and 350 ° C.

  The feedstock C1 to be treated was catalytically cracked gasoline with an initial boiling point of 55 ° C., an end point of 242 ° C., a MON of 79.8 and a RON of 89.5. Its sulfur content was 359 ppm by weight.

This feedstock is treated with catalyst A at a pressure of 2 MPa, the volume ratio of feedstock to be treated with hydrogen (H ₂ / HC) is 360 L / L, and the hourly space velocity (HSV) is 4 h ^{− 1} After the treatment, the gasoline and hydrogen mixture is cooled, the H ₂ S rich hydrogen is separated from the liquid gasoline, and the gasoline undergoes a stripping process by injecting a stream of hydrogen, leaving residual traces in the gasoline. An amount of dissolved H ₂ S was removed.

  Table 1 shows the effect of temperature on the desulfurization rate (%) and octane number of catalyst A at a hydrodesulfurization temperature of 240 ° C. (A1) or 270 ° C. (A2).

  Hydrodesulfurization of feedstock C1 with catalyst A provided a reduction in total sulfur content, and thiol content was also reduced. It should be noted that it was necessary to treat the feedstock at a minimum temperature of 270 ° C. to obtain about 11 ppm by weight of thiol. This temperature increase in the hydrodesulfurization reaction also had the effect of favoring the olefin hydrogenation reaction, which resulted in a decrease in the total olefin content in the desulfurized gasoline.

(Example 2: consistent with the present invention)
Catalyst B was obtained by impregnating nickel aluminate having a specific surface area of 135 m ² / g and a pore volume of 0.45 mL / g using an aqueous solution containing molybdenum and nickel. The catalyst was then dried and calcined at 500 ° C. in air. The content of nickel and molybdenum in this sample was NiO 7.9 wt% and _MoO 3 13% by weight.

Gasoline A1 as obtained and described in Example 1 was treated with dethiolation catalyst B in the absence of hydrogen. The pressure at that time was 1 MPa, HSV was 3 h ⁻¹ , and the temperature was 100 ° C. After the treatment, the gasoline B1 obtained was cooled.

  Table 2 shows the main characteristics of the gasoline B1 obtained.

  Therefore, carrying out the dethiolation step (step c)) means that without hydrogenation of olefins without hydrogen, gasoline A1 thiols could be converted.

(Example 3: consistent with the present invention)
Catalyst D was obtained by impregnating alumina having a specific surface area of 239 m ² / g and a pore volume of 0.6 mL / g using an aqueous solution containing molybdenum and nickel. The catalyst was then dried and calcined at 500 ° C. in air. The content of nickel and molybdenum in this sample was NiO 9.5 wt% and _MoO 3 13% by weight.

  Gasoline A1 as obtained and described in Example 1 was mixed with feed C2 to obtain feed C3. Feed C2 is light cracked gasoline that has undergone selective hydrogenation of diolefins, has an initial boiling point of 22 ° C. and an endpoint of 71 ° C., MON is 82.5, and RON is 96. It was 9. Its sulfur content was 20 ppm by weight, its thiol content was less than 3 ppm by weight, and its olefin content was 56.7% by weight.

  Feed C3 was obtained by mixing 80% by weight of gasoline A1 with 20% by weight of feed C2. The resulting mixture was a gasoline with an initial boiling point of 22 ° C and an end point of 242 ° C. Its sulfur content was 73 ppm by weight, its thiol content was 19 ppm by weight, and its olefin content was 31% by weight.

Feed C3 was treated with dethiolation catalyst D in the presence of hydrogen. The pressure at that time was 1 MPa, the hourly space velocity was 3 h ⁻¹ , the volume ratio of hydrogen to the feed to be treated (H ₂ / HC) was ₂ L / L, and the temperature was 100 ° C. . After treatment, the gasoline mixture was cooled and a gas phase rich in hydrogen and H ₂ S and a liquid gasoline fraction were recovered. The liquid fraction was stripped by injecting a stream of hydrogen to remove any trace amounts of H ₂ S that might have been dissolved in the gasoline.

  Table 3 shows the main characteristics of gasoline D1 obtained after stripping.

  The method is free of olefin hydrogenation and can therefore be used to reduce the thiol content of gasoline A1 by selectively converting thiols to thioethers without losing octane number.

FIG. 1 is a layout of a method according to a first embodiment of the present invention. FIG. 2 is a layout of a method according to the second embodiment of the present invention. FIG. 3 shows an alternative method layout according to the third embodiment. FIG. 4 shows a fourth embodiment of the method of the present invention.

Claims (22)

A method for treating a gasoline containing a sulfur-containing compound and an olefin, comprising at least the following steps:
a) contacting the gasoline, hydrogen and hydrodesulfurization catalyst in at least one reactor to convert at least a part of the sulfur-containing compound into H ₂ S, wherein the temperature is 200 Hydrogen in the range of ˜400 ° C., pressure in the range of 0.5-5 MPa, hourly space velocity in the range of 0.5-20 h ⁻¹ , and expressed in standard m ³ per hour. And the ratio between the flow rate of the feed to be treated, expressed in terms of volume m ³ per hour under standard conditions, is in the range of 50 to 1000 Nm ³ / m ³ ;
b) a step for separating H ₂ S formed and present in the effluent obtained from step a);
c) The H ₂ S depleted effluent obtained from step b) is contained in a reactor deposited with at least one transition metal or at least one lead sulfide on a porous support. A step of producing gasoline by contacting with a catalyst, the temperature at which step c) is performed is in the range of 30 to 250 ° C., and the liquid hourly space velocity is 0.5 to 10 h ⁻¹ . in the range, the pressure is in the range of 0.2 to 5 MPa, the ratio of _{H 2} / feedstock, Ri range der volume of feed ^{(m 3)} of hydrogen per 0～25Nm ^3, gasoline The thiol and olefin in it react to produce a thioether , and the gasoline obtained from step c) has a reduced thiol content compared to the thiol content of the effluent obtained from step b) . Process;
A method comprising:
Prior to step a), a process for distillation of gasoline is performed, and the gasoline is fractionated into at least two gasoline fractions, a light gasoline fraction and a heavy gasoline fraction, and a heavy gasoline fraction. In steps a), b) and c) . A method for treating a gasoline containing a sulfur-containing compound and an olefin, comprising at least the following steps:
a) contacting the gasoline, hydrogen and hydrodesulfurization catalyst in at least one reactor to convert at least a part of the sulfur-containing compound into H ₂ S, wherein the temperature is 200 in the range of to 400 ° C., the pressure is in the range of 0.5 to 5 MPa, hourly space velocity is in the range of 0.5 ~ 20h ^-1, hydrogen represented by standard ^{m 3} per hour And the ratio between the flow rate of the feed to be treated, expressed in terms of volume m ³ per hour under standard conditions, is in the range of 50 to 1000 Nm ³ / m ³ ;
b) a step for separating H ₂ S formed and present in the effluent obtained from step a) ;
c) The H ₂ S depleted effluent obtained from step b) is contained in a reactor deposited with at least one transition metal or at least one lead sulfide on a porous support. A step of producing gasoline by contacting with a catalyst, the temperature at which step c) is performed is in the range of 30 to 250 ° C., and the liquid hourly space velocity is 0.5 to 10 h ⁻¹ . In the range, the pressure is in the range of 0.2-5 MPa, the ratio of H ₂ / feedstock is in the range of 0-25 Nm ³ hydrogen per volume of feedstock (m ³ ) , in gasoline The thiol and olefin of the reaction react to produce a thioether, and the gasoline obtained from step c) has a reduced thiol content compared to the thiol content of the effluent obtained from step b), ;
A method comprising:
Before step a), a step for distillation of gasoline is performed, and the gasoline is fractionated into at least two gasoline fractions, a light gasoline fraction and a heavy gasoline fraction, and a heavy gasoline A process in which the fraction is treated in step a), the light gasoline fraction is mixed with the effluent obtained from step a) to form a mixture, and the mixture is treated in steps b) and c) . A method for treating a gasoline containing a sulfur-containing compound and an olefin, comprising at least the following steps:
a) contacting the gasoline, hydrogen and hydrodesulfurization catalyst in at least one reactor to convert at least a portion of the sulfur-containing compound to H ₂ In this step, the temperature is 200 to 400 ° C., the pressure is 0.5 to 5 MPa, and the hourly space velocity is 0.5 to 20 h. ^-1 Within the range of the standard m per hour ³ The flow rate of hydrogen represented by ³ The ratio between the flow rate of the feedstock to be treated, expressed as 50-1000 Nm ³ / M ³ Within the scope of the process;
b) H formed and present in the effluent obtained from step a) ₂ A step for separating S;
c) H obtained from step b) ₂ Contacting the effluent depleted of S in a reactor with a catalyst containing at least one transition metal or at least one sulfide of lead deposited on a porous support to produce gasoline. The temperature at which step c) is performed is in the range of 30-250 ° C., and the liquid hourly space velocity is 0.5-10 h. ^-1 The pressure is in the range of 0.2 to 5 MPa, H ₂ / Feedstock ratio is the volume of feedstock (m ³ ) 0-25Nm per hydrogen ³ The thioether in the gasoline reacts with the olefin to produce a thioether, and the gasoline obtained from step c) is lower than the thiol content of the effluent obtained from step b). Having a reduced thiol content;
A method comprising:
  Prior to step a), a step for distillation of gasoline is performed, and the gasoline is fractionated into at least three gasoline fractions, a light gasoline fraction, an intermediate gasoline fraction and a heavy gasoline fraction, respectively. And then treating the intermediate gasoline fraction in step a) and then in steps b) and c). Catalytic transition metals for step c) is a metal from group VIB is selected from metals and copper from group VIII, which are used alone or as a mixture, one of claims 1 to 3 the method according to one. The catalyst for step c) is
A carrier; constituted by gamma or delta alumina with a specific surface area in the range of 70-350 m ² / g;
An oxide of a metal from group VIB; an amount by weight in the range of 1 to 30% by weight relative to the total catalyst weight;
An oxide of a metal from group VIII; an amount by weight in the range of 1 to 30% by weight relative to the total catalyst weight;
Including
The sulfur content (%) of the constituent metals of the catalyst is at least 60%;
The process according to claim 4 , wherein the molar ratio between the metal from group VIII and the metal from group VIB is in the range of 0.6 to 3 mol / mol. 6. A method according to claim 4 or 5 , wherein the metal from group VIII is nickel and the metal from group VIB is molybdenum. The catalyst for step c) is
A carrier; constituted only by gamma alumina having a specific surface area in the range of 180-270 m ² / g;
Nickel oxide; an amount by weight in the range of 4 to 12% by weight relative to the total catalyst weight;
Molybdenum oxide; an amount by weight in the range of 6 to 18% by weight relative to the total catalyst weight;
Including
The nickel / molybdenum molar ratio is in the range of 1 to 2.5 mol / mol;
The method according to claim 6 , wherein a sulfidation rate (%) of a constituent metal of the catalyst is more than 80%. The effluent obtained from step b) causing the mixture is mixed with the light gasoline fraction, treating the mixture in step c), Method according to claim 1. 9. A process according to claim 2 or 8 , wherein the mixture contains up to 50% by volume of light gasoline fraction. The gasoline is contacted with hydrogen and a selective hydrogenation catalyst prior to step a) and prior to any optional distillation step to selectively hydrogenate diolefins contained in the gasoline to olefins. the method according to any one of 1-9. The catalyst for step a) contains at least one metal from group VIB and / or at least one metal from group VIII on a support having a specific surface area of less than 250 m ² / g, The amount of metal from group VIII, expressed as oxide, is in the range of 0.5 to 15% by weight, based on the weight of the catalyst, and the amount of metal from group VIB, expressed as oxide, is The process according to any one of claims 1 to 10 , which is in the range of 1.5 to 60% by weight with respect to the weight of the catalyst. The catalyst for step a) comprises cobalt and molybdenum, and the density of molybdenum expressed as the ratio between the MoO ₃ weight content and the specific surface area of the catalyst is greater than 7 × 10 ⁻⁴ g / m ^2. The method of claim 11 , wherein Performing step c) without the addition of hydrogen A process according to any one of claims 1 to 12. A method for treating a gasoline containing a sulfur-containing compound and an olefin, comprising at least the following steps:
a) contacting the gasoline, hydrogen and hydrodesulfurization catalyst in at least one reactor to convert at least a part of the sulfur-containing compound into H ₂ S, wherein the temperature is 200 Hydrogen in the range of ˜400 ° C., pressure in the range of 0.5-5 MPa, hourly space velocity in the range of 0.5-20 h ⁻¹ , and expressed in standard m ³ per hour. And the ratio between the flow rate of the feed to be treated, expressed in terms of volume m ³ per hour under standard conditions, is in the range of 50 to 1000 Nm ³ / m ³ ;
b) a step for separating H ₂ S formed and present in the effluent obtained from step a) ;
c) The H ₂ S depleted effluent obtained from step b) is contained in a reactor deposited with at least one transition metal or at least one lead sulfide on a porous support. A step of producing gasoline by contacting with a catalyst, the temperature at which step c) is performed is in the range of 30 to 250 ° C., and the liquid hourly space velocity is 0.5 to 10 h ⁻¹ . In the range, the pressure is in the range of 0.2-5 MPa, the ratio of H ₂ / feedstock is in the range of 0-25 Nm ³ hydrogen per volume of feedstock (m ³ ) , in gasoline The thiol and olefin of the reaction react to produce a thioether, and the gasoline obtained from step c) has a reduced thiol content compared to the thiol content of the effluent obtained from step b), ;
A method comprising:
Step a) is performed in a catalyst tower that separates gasoline into at least two gasoline fractions, a light gasoline fraction and a heavy gasoline fraction, and the light gasoline fraction is treated in steps b) and c). that way. Further comprising step d), wherein in step d) the effluent obtained from step c) is sent to a fractionation column and a gasoline fraction having a low thiol content is separated from the head of the fractionation column; the hydrocarbon fractions containing the thioether compound is separated from the bottom of the fractionation column, the method according to any one of claims 1-14. The process according to claim 15 , wherein steps c) and d) are carried out continuously in a catalytic distillation column comprising a bed of catalyst for step c). The resulting effluent from step b), LPG fraction is selected crude distillation, thermal cracking unit, coking device, gasoline fraction obtained from a hydrocracker or oligomerization apparatus, and olefin C ₄ fraction mixed with the hydrocarbon fraction, the mixture is treated in step c), method according to any one of claims 1-16. When the effluent obtained from step b) is treated as a mixture with the olefin C ₄ fraction, the effluent obtained from step c) is fractionated to separate the unreacted olefin C ₄ fraction, the unreacted olefin C ₄ fraction is recycled to the reactor for step c), the method of claim 17. The process according to claim 14, wherein the transition metal of the catalyst for step c) is selected from metals from group VIB, metals from group VIII and copper, which are used alone or as a mixture. The catalyst for step c) is
・ Carrier; specific surface area of 70-350m ² Constituted by gamma or delta alumina in the range of / g;
An oxide of a metal from group VIB; an amount by weight in the range of 1 to 30% by weight relative to the total catalyst weight;
An oxide of a metal from group VIII; an amount by weight in the range of 1 to 30% by weight relative to the total catalyst weight;
Including
The sulfur content (%) of the constituent metals of the catalyst is at least 60%;
20. The method of claim 19, wherein the molar ratio between the metal from Group VIII and the metal from Group VIB is in the range of 0.6-3 mol / mol. 21. The method of claim 19 or 20, wherein the metal from Group VIII is nickel and the metal from Group VIB is molybdenum . The catalyst for step c) is
-Carrier; specific surface area of 180-270m ² Composed only of gamma alumina in the range of / g;
Nickel oxide; an amount by weight in the range of 4 to 12% by weight relative to the total catalyst weight;
Molybdenum oxide; an amount by weight in the range of 6 to 18% by weight relative to the total catalyst weight;
Including
The nickel / molybdenum molar ratio is in the range of 1 to 2.5 mol / mol;
The method according to claim 21, wherein a sulfidation rate (%) of a constituent metal of the catalyst is more than 80%.

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