JP2006144020A - Method for desulfurizing hydrocarbon fraction in simulated moving bed - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for desulfurizing a distillate type hydrocarbon fraction by adsorption in a simulated moving bed without causing the substantial excessive consumption of hydrogen and/or the increase of an operation pressure. <P>SOLUTION: The present invention describes a method for desulfurizing a gas oil type hydrocarbon fraction by adsorption to obtain the desulfurized distillate having a sulfur content of <10 wt. ppm in a yield of >95 wt.%. The method includes a process for adsorbing sulfur-containing compounds in an oil of raw material in a simulated moving bed, an extraction residual oil distillation process, and an extraction distillation process. A solid adsorbent used in an adsorption device is preferably activated carbon having a specific surface area of >1,200 m<SP>2</SP>/g and a total fine pore volume of 0.5 cm<SP>3</SP>/g. It is preferably that the fine pore volume of the micropores of the adsorbent is >0.2 cm<SP>3</SP>/g. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for desulfurization of a distillate-type hydrocarbon fraction by adsorption on a simulated moving bed. The term “distillate-type fraction” means a fraction having a distillation range of 150-450 ° C. from a conversion unit such as distilled crude oil or catalytic cracking.

  In the description below, this fraction is referred to as the “light oil” fraction, but this designation does not have any limiting character. Any hydrocarbon fraction containing sulfur and having a distillation range similar to that of the light oil fraction may be used in the process of the present invention.

Thus, the process of the present invention starts with a feedstock to be treated with a sulfur content from several tens of ppm to 2% or 3% by weight, with sulfur (S) not exceeding 10 ppm by weight, and even 5%. It can be used to produce a desulfurization fraction that is not more than ppm by weight, and even not more than 1 ppm by weight. The notation “ppm by weight” means parts per million by weight and is equal to 10 ⁻⁶ kg / kg.

  Moreover, the diesel oil yield of the above process is substantially higher than the diesel oil yield of the fixed bed process.

  Future standards for automotive fuels stipulate a significant reduction in the sulfur content of fuels, particularly light oil. This reduction is intended to limit the sulfur oxide and nitrogen content in automobile exhaust. European law stipulates that diesel oil should be reduced to 350 ppm by weight in 2000, sulfur content to 50 ppm by weight in 2005, and sulfur to 10 ppm by weight in 2009. The fuel standard is clarified.

  In this way, changes in specifications for sulfur content in fuels can improve existing catalytic hydroprocessing methods that result in substantial overconsumption of hydrogen and / or increased operating pressure, or new for diesel There is a need to either develop a sophisticated desulfurization process or to combine the two.

  The light oil desulfurization method includes a method of purifying a sulfur-containing compound by adsorption on a selective adsorbent, and provides an advantage over the conventional hydrodesulfurization method.

  For example, U.S. Patent No. 6,057,049 describes a simulated moving bed of a naphtha fraction (a term used by those skilled in the art to indicate a gasoline fraction with an initial boiling point of about 70 ° C and an end boiling point of about 220 ° C). In order to separate polar compounds (sulfur-containing compounds, nitrogen-containing compounds, oxygen-containing compounds) by SMB) separation, it is recommended to use KX type zeolite and 1-octanol type desorbent.

  The sulfur-containing compounds present in the naphtha fraction are of the thiophene type and are most difficult to remove in the case of distillates, ie those encountered in the context of the present invention, benzo or It is not of dibenzothiophene type.

Patent Document 2 describes a light oil desulfurization method, which is difficult to remove from a conventional hydrotreatment for removing a sulfur-containing compound known as an “easy sulfur” method. And a method for adsorbing a sulfur-containing compound on activated carbon having a specific surface area of 800 to 1200 m ² / g and a specific pore structure. The sulfur-containing compounds that are difficult to remove, referred to as “hard sulfur”, are aromatics of the beta-substituted dibenzothiophene type.

  The adsorption method described in the above patent is not designed to completely process the starting gas oil feedstock and requires a pre-hydrogenation treatment.

Patent Document 3 proposes a method for desulfurizing a hydrocarbon feedstock based on a complex solid based on a π electron acceptor. Prior to this process, the separation may be performed by a column capable of producing a light effluent to specification and a heavy effluent that requires desulfurization. In the case of fixed bed operation, the loss of product to be desulfurized by physically filling the pore volume of the adsorbent is not negligible. The above-mentioned patent document proposes a correction method that can reduce the loss of hydrocarbons for this purpose by using different cleaning fluids having variable adsorption power, but the loss of hydrocarbons can be completely avoided. Do not mean.
U.S. Pat. No. 4,337,156 (UOP 1982) US Pat. No. 5,454,933 French Patent Application Publication No. 02/03314

  It is an object of the present invention to provide a method for desulfurization of distillate-type hydrocarbon fractions by adsorption on a simulated moving bed that does not result in substantial overconsumption of hydrogen and / or increase in operating pressure. To do.

The present invention is an advanced desulfurization method of a gas oil type hydrocarbon feedstock having a distillation range of 150 to 450 ° C. and may contain up to 3% sulfur,
-Carried out in at least one first adsorption column comprising a plurality of beds which function as simulated moving beds and are composed of adsorbed solids having different selectivity for sulfur-containing hydrocarbons and non-sulfur-containing hydrocarbons; The column has a first zone between a point for introducing the desorbent and a point for extracting the extract, a second zone between the point for extracting the extract and the point for introducing the feedstock. A third zone between the point for introducing the feedstock oil and the point for extracting the extraction liquid, the point for extracting the raffinate and the point for introducing the desorbent; Adsorbing sulfur-containing compounds from the feedstock to be treated comprising four functional zones of the fourth zone between
-Distilling the extraction liquid, carried out in at least one distillation column, wherein a desorbent stream is withdrawn from which the gas oil effluent and at least a part are recycled to the first adsorption column;
An extract which is carried out in at least one distillation column and from which the effluent containing sulfur-containing impurities is withdrawn together with a substantially pure desorbent stream which is at least partially recycled to the first adsorption column. And a step of continuously including the step of distillation.

  The sulfur content of the light oil obtained is generally less than 10 ppm by weight, preferably less than 5 ppm by weight, more preferably less than 1 ppm by weight, and the yield for the injected feedstock is generally greater than 97%. , Preferably more than 99%.

  In a variation of this method, the feedstock to be treated is first sent to a distillation column located upstream of the simulated moving bed adsorber, from which the top stream is drawn and withdrawn. At least a portion is used as a desorbent and a bottom stream is withdrawn, which may be introduced into the simulated moving bed adsorber as a feedstock.

  The desulfurization method of the present invention is an advanced desulfurization method of hydrocarbon feedstock having a distillation range of 150 to 450 ° C. and containing up to 3% sulfur, which functions as a simulated moving bed, and contains sulfur-containing hydrocarbons and Performed in at least one first adsorption column (2) comprising a plurality of beds of adsorbent having different selectivity with non-sulfur containing hydrocarbons, the column comprising at least 4 functional zones, The second zone is between the point for introducing the desorbent (9b) and the point for extracting the extract (4), and the second zone for extracting the extract (4) and the feed oil (1 ) Between the point for introducing the feedstock oil (1) and the point for extracting the residual extraction liquid (3), and the third zone In order to introduce the point for extracting the extraction residual liquid (3) and the desorbing agent (9b) Adsorbing sulfur-containing compounds from feedstock (1), wherein the volume ratio of desorbent to feedstock is between 0.5 and 2.5, and at least one distillation column (5) The extraction residue (3) is withdrawn from the stream of gas oil effluent (8) desulfurized from the column and the desorbent (9) at least partially recirculated to the first adsorption column (2). ) And a desorbent in which at least a portion of the effluent (10) containing sulfur-containing impurities is recycled to the first adsorption column in the at least one distillation column (6). Distilling the extract (4) withdrawn with the substantially pure stream (11).

  In the desulfurization method of the present invention, the sulfur content of the desulfurized gas oil (8) is less than 10 ppm by weight, preferably less than 5 ppm by weight, more preferably less than 1 ppm by weight. The yield relative to the inlet feedstock is generally greater than 97% by weight, preferably greater than 99% by weight.

In the desulfurization method of the present invention, the solid adsorbent used in the adsorption apparatus is preferably activated carbon having a specific surface area of more than 1200 m ² / g and a total pore volume of 0.5 cm ³ / g.

In the desulfurization method of the present invention, it is preferable that the pore volume portion of the micropores of the adsorbent is more than 0.2 cm ³ / g.

  In the desulfurization method of the present invention, the operation temperature of the adsorbent apparatus is 50 to 350 ° C, preferably 50 to 250 ° C.

  In the desulfurization method of the present invention, the simulated moving bed adsorber preferably includes at most 24 beds, preferably at most 15 beds.

  In the desulfurization method of the present invention, the volume ratio of the desorbent of the simulated moving bed adsorber to the raw material oil is preferably 0.7 to 2.0.

  In the desulfurization method of the present invention, the feed oil to be treated is first sent to a distillation column located upstream of the simulated moving bed adsorber, and the top stream (1a) is extracted from the distillation column. , At least a part of which is used as a desorbent and the bottom stream (1b) is withdrawn, which is preferably introduced into the simulated moving bed adsorber (2) as feedstock.

  In the desulfurization method of the present invention, the sulfur-containing compound stream (10) is preferably sent to the fuel oil fraction (fuel) as a mixture.

  In the desulfurization method of the present invention, the sulfur-containing compound stream (10) is preferably recycled to the hydrodesulfurization unit.

  The present invention describes a method of desulfurizing a via-type hydrocarbon fraction by adsorption to obtain a desulfurized effluent containing less than 10 ppm by weight in a yield of more than 95% by weight. The method includes a simulated moving bed adsorption step, a extracted residue distillation step, and an extractive distillation step of a sulfur-containing compound in a raw material oil.

  The present invention is carried out in at least one first adsorption column (2) that functions as a simulated moving bed and that includes a plurality of beds of adsorbent that have different selectivity for sulfur-containing hydrocarbons and non-sulfur-containing hydrocarbons. The column comprises at least 4 functional zones, the first zone being between the point for introducing the desorbent (9b) and the point for withdrawing the extract (4); The zone is between the point for extracting the extract (4) and the point for introducing the feed oil (1), and the third zone is the point for extracting the feed oil (1). The fourth zone is between the point for extracting the residual liquid (3) and the point for introducing the desorbent (9b). The sulfur-containing compound from the feed oil (1), wherein the volume ratio of the desorbent to the feed oil is 0.5 to 2.5 An adsorbing step and a desorbent (9) which is carried out in at least one distillation column (5) and desulfurized from the column, and at least part of which is recycled to the first adsorption column (2). ) In which at least one distillation column (6) and at least a portion of the effluent (10) containing sulfur-containing impurities are distilled. Distilling the extract (4) withdrawn with a substantially pure stream (11) of desorbent that is recycled to the first adsorption column, so that there is a substantial excess consumption of hydrogen and It is possible to provide a method for desulfurization of a distillate-type hydrocarbon fraction by adsorption in a simulated moving bed without causing an increase in operating pressure.

  The invention will be better understood from the method flow sheet shown in FIG.

  The feed oil (1) enters the adsorptive desulfurization device (2) that is driven as a simulated moving bed. This adsorptive desulfurization unit is constituted by at least one adsorption column, which has a selectivity that favors sulfur-containing compounds over the chemical series of raw oils to be refined (alkanes and aromatics). Includes a plurality of interconnected adsorption beds.

  The adsorption column includes at least four zones, and the four zones include the inlet of the mixture (1) constituting the adsorption and desorption raw material oil (9b), and the extracted liquid containing desulfurized gas oil mixed with the desorbent. The range is determined by the outlet of the extract (4) mainly containing the sulfur-containing compound removed as a mixture with (3) and the desorbent.

  Zone 1 for desorption of the sulfur-containing compound is contained between the inlet for the desorbent (9b) and the outlet for the extract (4).

  Zone 2 for the desorption of alkanes and aromatics is between the extract (4) outlet and the adsorbed feedstock (1) inlet.

  Zone 3 for adsorption of sulfur-containing compounds is between the feedstock (1) inlet and the extracted residual oil (3) outlet.

  The zone 4 is located between the extraction port of the extraction residual liquid (3) and the injection port of the desorbent (9b), and can adsorb alkane and aromatic.

  The step of separating the streams (3) and (4) is carried out by two distillation columns (5) and (6) supplied with the extraction liquid (3) and the extract (4), respectively. The distillation columns (5) and (6) can remove substantially all of the desorbent, for example at the bottom of the column.

  A desulfurized gas oil stream (8) containing less than 10 ppm by weight, preferably less than 5 ppm by weight, more preferably less than 1 ppm by weight, is withdrawn from the top of the column (5) to produce sulfur-containing compounds and nitrogen. A mixture (10) of containing compounds is withdrawn from the top of the column (6).

  The mixture itself may advantageously be mixed with a refinery stream, for example fuel oil, having a suitable sulfur specification and whose boiling point is similar to that of the produced mixture.

  This mixture may also be recycled to conventional hydroprocessing equipment that can remove the recycled sulfur-containing compounds by increasing the sulfur content of the feedstock. This is because the catalytic activity of the hydrodesulfurization process is directly related to the inlet concentration of sulfur to be treated.

  Desorbents (9) and (11) are recovered from the bottoms of columns (5) and (6) and are appropriate make-up desorbents corresponding to any loss of desorbent received in distillation columns (5) and (6) The flow (9a) returned to the simulated moving bed (SMB) desulfurization device (2) is formed together with (12).

  The various streams (9), (11) and (12) form an additional desorbent (9b) which is introduced into the simulated moving bed column (2).

  Stream (7) constitutes the recirculation flow that is essential for operation of the simulated moving bed column. It is made up of recycled solvent and light oil with a time varying ratio.

  FIG. 2 describes a variant in the invention, in which the distillation step corresponding to the device (1e) is arranged upstream of the flow sheet described in FIG.

  This distillation step consists of a step of sending the raw oil (1) to a distillation column (1e) for producing a heavy sulfur-containing hydrocarbon fraction (1b), which is shown in FIG. The heavy sulfur-containing hydrocarbon fraction (1b) sent to the SMB adsorber (2) and the light hydrocarbon fraction (1a) having a sulfur content below the required standard are produced.

  The desulfurized sulfur (1a) may also be used as a desorbent in the SMB adsorber (2), in which case once reaching a quasi-stable state, part (1d) of the stream (1a) is Used as make-up desorbent and mixed with stream (9a) to form desorbent stream (9b) in adsorption column (2). The remaining part of the desulfurized light hydrocarbon (1c) meets already required standards and can therefore serve as a base in commercial light oil.

  In a variant of the process, it is possible to treat light oil that would have been desulfurized in conventional catalytic hydrodesulfurization equipment well known to those skilled in the art.

  The sulfur content of light oil produced by the above equipment will vary depending on the hydroprocessing operating conditions. The sulfur content of the light oil produced can be from 10 to 1000 ppm by weight, which can be treated using any of the method variants of the invention corresponding to FIGS.

  Adsorbents used in SMB equipment are typically activated carbon, zeolite, silica, alumina, silica-alumina, spent catalyst, resin, clay, crosslinked clay, reduced metal or metal oxide and various adsorbent series. Selected from conventional adsorbent series of any possible mixture in between.

According to one characteristic of the method, the adsorbent used in the SMB adsorber is selected from the activated carbon series. This is because these solids have sufficient selectivity between sulfur-containing molecules and other light oil substrates. Preferred activated carbon types are those with a specific surface area greater than 1200 m ² / g and a total pore volume greater than 0.5 cm ³ / g, and the precursor can be of any type and has a porosity. The type of activation used to form can be either physical or chemical or a combination of both.

Whatever the adsorbed solid used in the present method, the total pore volume is preferably 0.5 cm / g or more, and the portion of the pore volume contained in the micropores of the solid adsorbent is preferably Is 0.2 cm ³ / g or more.

Microporosity is defined as the category of pores having a diameter of less than 20 angstroms (2 nm, ie 2 × 10 ⁻⁹ m).

  The number of adsorbent beds constituting the simulated moving bed adsorber is generally less than 24, preferably less than 15.

  The desorbent may be selected from a chemical series of nitrogen-containing compounds, alcohols, ethers, aromatics, desulfurized light fractions, or any other stream or mixture thereof. For example, aromatics may be preferably selected.

  The volume ratio of the desorbent to the feed oil in the simulated moving bed separator is generally 0.5 to 2.5, preferably 0.7 to 2.0.

  The operating temperature may be between room temperature and the end point of the hydrocarbon fraction to be treated, with the understanding that liquid phase operation is required. Generally, a temperature of 50 to 350 ° C is used, and preferably 50 to 250 ° C.

  Operating pressure is understood that the results of this method are almost independent of this parameter, the bubble point of the lightest compound to ensure the presence of the liquid phase through the SMB adsorber and 15 absolute bar (1 .5 MPa). However, it can be affected with respect to equipment costs.

A specific surface area of 1440 m ² / g, a total pore volume of 1.7 cm ^{3 /} g, a pore volume portion of the microporosity of 0.35 cm ³ / g, and various effluent series Consider the following elution order activated carbon:
・ Alkane;
Aromatic: mono-, di- and tri-;
Easy sulfur (sulfur-containing compounds that are easy to remove);
・ Refractory sulfur (sulfur-containing compounds that are difficult to remove);
-Nitrogen-containing compounds.

(Example of processing low sulfur gas oil (sulfur 50 ppm))
15 oils of 609.6 cm ^{3 each} divided into 4 zones (zone 1 = 3 beds, zone 2 = 4 beds, zone 3 = 5 beds and zone 4 = 2 beds) containing 50 wt ppm sulfur. Purified in a simulated moving bed on a pilot device containing the floor.

The operating conditions are as follows:
Temperature: 210 ° C .;
Pressure: so that there is a liquid phase at all points in the circuit, ie 3 absolute bar (0.3 MPa);
Inlet, outlet and recirculation flow rate and operating conditions:
Feedstock: 200.0 cm ³ / min;
Solvent (toluene): 147.0 cm ³ / min;
Extract: 57.0 cm ³ / min;
Extraction residual liquid: 290.0 cm ³ / min;
Recirculation flow rate (zone 1): 193 cm ³ / min.

  The valve permutation time (or duration) was 152.0 seconds.

After distillation of toluene, the resulting extraction residue had a sulfur content of 1.5 wt. And released 99.5% pure gas oil. Productivity of the device is expressed as the volume of the produced diesel fuel per volume and per unit of adsorbent time was ^{1.31m 3 / (m 3 · h} ).

(Example of processing light oil with high sulfur content (1.5% sulfur))
609.6 cm ³ of 15 light oils containing 1.5% by weight of sulfur, each divided into 4 zones (zone 1 = 3 beds, zone 2 = 5 beds, zone 3 = 5 beds and zone 4 = 2 beds) Purified in a simulated moving bed on a pilot device containing the floor.

The operating conditions are as follows:
Temperature: 210 ° C .;
Pressure: so that liquid is present at all points in the circuit;
Infusion, withdrawal and recirculation flow rates and operating conditions:
Feedstock: 105 cm ³ / min;
Solvent (toluene): 147.0 cm ³ / min;
Extract: 82.0 cm ³ / min;
Extraction residual liquid: 170.0 cm ³ / min;
Recirculation flow rate (zone 1): 193 cm ³ / min;
The valve replacement time (or period) was 152.0 seconds.

After distilling toluene, the resulting extraction residue had a sulfur content of 3.5 ppm by weight and released 99.5% pure gas oil. Productivity of the device is expressed as the volume of the produced diesel fuel per volume and per unit of adsorbent time was ^{0.67m 3 / (m 3 · h} ).

2 shows a flow sheet of the method of the invention in the most general scope. 6 shows a variation of the flow sheet of the method according to the invention.

Claims (10)

An advanced desulfurization method for hydrocarbon feedstock having a distillation range of 150 to 450 ° C. and containing up to 3% sulfur,
Carried out in at least one first adsorption column (2) which functions as a simulated moving bed and comprises a plurality of beds of adsorbent which have different selectivity for sulfur-containing hydrocarbons and non-sulfur-containing hydrocarbons, , Including at least 4 functional zones, the first zone is between the point for introducing the desorbent (9b) and the point for extracting the extract (4), the second zone is for extraction Between the point for extracting the liquid (4) and the point for introducing the raw material oil (1), the third zone is the point for introducing the raw material oil (1) and the residual liquid (3 ) Between the point for extracting the extraction residual liquid (3) and the point for introducing the desorbent (9b), and the fourth zone is The desorbent has a volume ratio of 0.5 to 2.5, and adsorbs sulfur-containing compounds from the raw oil (1). And the extent,
A stream of gas oil effluent (8) desulfurized from the column and desorbent (9), at least part of which is recycled to the first adsorption column (2), is carried out in at least one distillation column (5). A step of distilling the extracted residual liquid (3),
A substantially pure stream of desorbent (10) carried out in at least one distillation column (6), from which the effluent (10) containing sulfur-containing impurities is recycled at least partly to the first adsorption column ( And 11) distilling the extract (4) withdrawn.   The sulfur content of the desulfurized gas oil (8) is less than 10 ppm by weight, preferably less than 5 ppm by weight, more preferably less than 1 ppm by weight. The yield of the desulfurized gas oil (8) with respect to the inlet feedstock is The advanced desulfurization process according to claim 1, which is generally more than 97% by weight, preferably more than 99% by weight. ^3. The advanced desulfurization according to claim 1 or 2, wherein the solid adsorbent used in the adsorber is activated carbon having a specific surface area of more than 1200 m ² / g and a total pore volume of 0.5 cm ³ / g. Method. The advanced desulfurization method according to claim 1, wherein a portion of the pore volume of the micropore of the adsorbent is more than 0.2 cm ³ / g.   The advanced desulfurization method according to any one of claims 1 to 4, wherein an operating temperature of the adsorbent apparatus is 50 to 350 ° C, preferably 50 to 250 ° C.   6. The advanced desulfurization method according to any one of claims 1 to 5, wherein the simulated moving bed adsorber comprises at most 24 beds, preferably at most 15 beds.   The advanced desulfurization method according to any one of claims 1 to 6, wherein the volume ratio of the desorbent of the simulated moving bed adsorber to the raw material oil is 0.7 to 2.0.   The feedstock to be treated is first sent to a distillation column located upstream of the simulated moving bed adsorber, from which a top stream (1a) is withdrawn, at least part of which is a desorbent. The advanced desulfurization method according to any one of claims 1 to 7, wherein the bottom stream (1b) is withdrawn and introduced into the simulated moving bed adsorber (2) as feedstock .   9. The advanced desulfurization process according to any one of claims 1 to 8, wherein the sulfur-containing compound stream (10) is sent as a mixture to a fuel oil fraction (fuel).   10. The advanced desulfurization method according to any one of claims 1 to 9, wherein the sulfur-containing compound stream (10) is recycled to the hydrodesulfurization unit.

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