KR101958512B1 - Improved process for converting a heavy feedstock into middle distillates using a pretreatment upstream of the catalytic cracking unit - Google Patents

Abstract

The present invention describes an improved process for the conversion of heavy feeds which allows to improve selectivity to intermediate distillates. The present invention consists in carrying out a hydrotreating or hydrogen conversion process, referred to as pretreatment, of the heavy feedstock upstream of the assembly of the oligomerization apparatus after the catalyst cracking apparatus, which is characterized in that at the end of the catalyst cracking apparatus, C3, To thereby increase the net production of intermediate distillates after the oligomerization step and thus to increase the selectivity of intermediate distillates to petroleum.

Description

Technical Field [0001] The present invention relates to an improved process for converting a heavy feedstock into a middle distillate using a pretreatment upstream of a catalytic cracking unit. BACKGROUND OF THE INVENTION < RTI ID = 0.0 > [0001] < / RTI &

SUMMARY OF THE INVENTION The present invention is directed to an improved method of converting heavy hydrocarbon feedstocks to improve the yield of intermediate distillates. More precisely, the method of the present invention can be used for the following:

Improving the production of intermediate distillates for the feed;

Substantially improving the selectivity of the middle distillate to gasoline;

• obtain C3, C4 and light gasoline cuts with low levels of impurities, yielding substantial benefits in relation to the service life of the catalyst used in the oligomerization unit or the purification steps necessary prior to the oligomerization step.

This improvement is possible by means of a hydrogen treatment or hydrogen conversion device which is referred to as a pre-treatment device disposed upstream of a continuous catalyst cracking device and an oligomerization device.

Historically, catalyst cracking, commonly known as the abbreviation FCC (fluid catalytic cracking), has been used to meet the polymer related market resulting from the polymerization of light olefins or to meet the gasoline consumption requirements of the automotive industry; (LPG), light olefins and gasoline.

In this type of function, the manufacture of gas oil bases is limited. At present, there is a major growth in the use of diesel in the automotive industry, and the demand for gas oil type products is increasing significantly. Thus, it is increasingly necessary to direct the production from the tablet to the preparation of the intermediate distillate and to improve the selectivity of the middle distillate to gasoline.

FCC devices present in nearly half of the purifiers are essential to be able to convert the device to the preferred device for the production of intermediate distillate, since it is on the one hand a major source of gasoline and on the other hand a major source of light olefins.

In the context of the present invention, which includes pre-treatment through a hydrogenation or hydrogen conversion arrangement disposed upstream of the catalyst cracking unit, the final preparation of intermediate distillates obtained from the FCC unit + oligomerization unit ensembles is increased, A more diverse feedstock can be obtained which can be used to improve the middle distillate selectivity.

Another advantage of the present invention is to facilitate the purification of the feed for the oligomerization apparatus and thus to increase the duration of the catalytic cycle by providing a feed having a reduced impurity content, such as nitrogen or sulfur. The "pre-treatment" device upstream of the FCC and oligomerization ensembles can be used for all hydrogenation purification reactions such as hydrogenation denitration, hydrodesulfurization, and hydrogenation of aromatics at high hydrogen pressure and heavy feed hydrogen conversion, Processing device.

This process can be used to partially convert the heavy hydrocarbon feed having an initial boiling point, which is generally above 340 DEG C, under partial pressure of hydrogen to gasoline and a middle distillate and hydrotreate the resulting cut and untransformed heavy hydrocarbon feedstock , Which means that the amount of impurities, especially the nitrogen-containing and sulfur-containing compounds, can be reduced.

The FCC process can be used to convert heavy hydrocarbon feeds having an initial boiling point generally above 340 DEG C into a harder hydrocarbon fraction, particularly a gasoline cut, by cracking the molecules of the heavy feed in the presence of an acid catalyst. FCC also produces large quantities of LPG (liquefied petroleum gas) with high olefin content. In the present invention, the FCC feed consists of unconverted feed from a hydrogenation refinery.

The purpose of the oligomerization process is to produce a number of distinct cuts, such as C3 to C4 cuts, and C5-220 deg. C, preferably 160 deg. C, more preferably C5-120 deg. C gasoline cuts, Oligomers C3 to C12 olefins to obtain mixtures of hydrocarbons containing mono-olefins, predominantly containing at least 9 carbon atoms.

Starting with C4 olefins, oligomers are obtained that contain typically no more than 30, principally 8 to 20, carbon atoms.

The present invention employs certain continuous devices that can be used in the following:

a) to improve the overall intermediate distillate production;

b) to improve the selectivity of the middle distillate to gasoline; And

c) to facilitate the purification of the oligomerization apparatus and to provide a feed having a reduced amount of impurities such as nitrogen, sulfur or even diolefins to increase the duration of the catalytic cycle.

The present invention is essentially to provide a hydrotreating or hydrogenation unit upstream of a catalyst cracking apparatus that can be used to increase the overall production of the middle distillate.

The arrangement of such devices can also be used to significantly increase the selectivity of the middle distillate to gasoline.

Another significant effect of the present invention is that it can be used to produce gasoline cuts obtained from catalytic cracking with reduced amounts of impurities such as nitrogen and sulfur and diolefins.

The refined gasoline cut can thus be used to limit refining upstream of the oligomerization apparatus and increase the catalyst cycle time.

The present invention is compatible with all catalytic cracking reactor technologies, whether they are riser or dropper types.

The catalyst cracking apparatus used in the process of the present invention can be divided into several embodiments, using a single reactor or a plurality of reactors (each reactor may function in a riser or dropper manner).

In the case where a plurality of oligomerization apparatus is associated with a catalyst cracking apparatus, such apparatus may be arranged in series or in parallel.

Prior art experiment

The patent application FR 2 935 377 relates to a process for the conversion of known hydrocarbon feeds into heavy feeds in view of the co-production of propylene and gasoline in minimum yield. The process described in this patent comprises a second step for the oligomerization of C4 and C5 olefins obtained from two or more reaction steps, a first step for catalyst cracking and C3 and C4 olefins, or C4 olefins, or catalyst cracking. A third reaction step for selective hydrogenation of olefins may be necessary prior to oligomerization in certain cases.

The inventive method can be used to perform two types of manufacturing, corresponding to two separate market scenarios:

"Maximum Propylene" scenario, corresponding to maximum production of propylene, while maintaining the minimum gasoline yield or even slightly increasing the potential yield from catalyst cracking apparatus alone; or

● "Max gasoline" scenario, corresponds to the maximization of gasoline production without propylene production.

Patent WO 03/078547 describes a method of catalytic cracking of a second, relatively rigid feed with a main feed having a boiling point above 350 DEG C and a boiling point below 320 DEG C, said secondary feed comprising 4 or 5 Lt; RTI ID = 0.0 > 8 < / RTI > carbon atoms prepared by oligomerization of light olefins containing one or more carbon atoms.

Patent WO 03/078364 describes a process for preparing oligomers from C4 olefins, which are then cracked in a catalyst cracking apparatus, with a view to maximizing propylene production.

The patent application FR 11/01444 describes a catalyst cracking / oligomerization device sequence.

This application describes a method for the conversion of a heavy feed which can be used to improve the selectivity of the middle distillate. The process uses at least one apparatus for the oligomerization of olefins of 2 to 12 carbon atoms after the catalyst cracking apparatus, which means that additional intermediate distillation cuts can preferably be prepared. The hard fraction of the oligomer produced, which can not be incorporated into the middle distillate cut, is recycled in part to:

An oligomerization step for transformation into a middle distillate by reaction of the feed with light olefins, as described in patent FR 2 871 167; or

FCC for cracking with a light olefin returned to the oligomerization apparatus as a supplement to the olefin of the feed to form a heavy oligomeric material which can be incorporated into the middle distillate cut.

The present invention consists of three specific successive devices that can be used to significantly improve the production of intermediate distillates and the intermediate distillate selectivity to gasoline, which is presently the most desirable in terms of turning demand from gasoline into gas oil do.

The series described in this invention can also be used to produce refined gasoline cuts from FCC having reduced amounts of impurities such as sulfur, nitrogen and diolefins (this cut is then fed to an oligomerization apparatus to produce olefin having a high molecular weight corresponding to a middle distillate cut To improve the service life and performance of the catalyst used in the oligomerization apparatus.

The sequence of the process of the present invention may be carried out in the form of a hydrogenation purification apparatus such as a mild or intense hydrocracking unit (commercial name given to it by AXENS is HyC or HyK-HP) (Commercial name given to it by AXENS is Hyvahl / Hoil _DC / Hoil _RC ), followed by all or only some C3, C4 and all gasoline and FCC from the fixed bed or ebullated bed hydrotreating And is configured using one or more oligomerization apparatuses that process gasoline cuts.

The synergistic effect of the series of the present invention can be used to increase the total amount of intermediate distillate produced compared to a simple sequence consisting of a catalyst cracking apparatus and an oligomerization apparatus as described in the prior art.

The series of the present invention can be used to obtain a refined gasoline cut which substantially substantially improves the selectivity of the middle distillate for gasoline selectivity and is also sent to the oligomerization unit; This is a clear advantage in terms of catalyst performance and service life.

Brief Description of Drawings

Figure 1 shows the layout of the method of the invention in which the device is represented as follows:

(PRET) for pre-processing;

(FCC) for catalyst cracking;

(PUR) oligomerization purification apparatus upstream;

(OLG) for the oligomerization apparatus; And

For an apparatus for hydrotreating a middle distillate cut obtained from (HDT) oligomerization.

The present invention relates to a process for the conversion of a feed comprising a hydrocarbon feed, referred to as a heavy feed, i.e. a hydrocarbon having a boiling point of greater than about 340 ° C, in view of improving the production of intermediate distillates constituting the base for commercial gas oil will be.

The method of the present invention can be used to achieve the following three purposes:

1) Increases the production of intermediate distillates by:

• Feed production that can be converted to a large scale in the FCC, which has the advantage of yielding increased production of C3, C4 olefins and light gasoline that can be used to produce more intermediate distillates when converted from an oligomerization unit ;

● the intrinsic manufacture of intermediate distillates through pre-treatment equipment;

2) very significantly increase the selectivity of the middle distillate to gasoline;

3) Obtain a gasoline cut obtained from catalytic cracking, having an impurity content with reduced nitrogen and sulfur and diolefin content, to increase the catalytic cycle time and limit the refining upstream of the oligomerization apparatus.

The process of the present invention can be defined as a process for the production of a middle distillate from a vacuum gas oil or heavy feed (1) of an atmospheric residue type using the following four steps:

- a) carried out in a hydrocracking or hydrotreating device to reduce the amount of sulfur-containing and nitrogen-containing impurities in the feed, and the diolefin content thereof, and having a C5-160 ° C gasoline cut (3) (PRET) which yields a first intermediate distillate cut (4) having a distillation range in the range of from about 1 to about 10, and an unconverted fraction (5) having substantially the same distillation range as the incoming heavy feed;

b) cut 7, C3 cut 8, C4 cut 9, C5-160 deg. C gasoline cut 10, and second intermediate distillate 10, referred to as dry gas cuts, For the catalytic cracking (FCC) of the unconverted fraction (5) obtained from the pre-treatment step (PRET) producing the cut (11), said gasoline cut (10) being sent to the purification device (PUR);

c) a gasoline cut 10 'obtained from the cut C3 (8), the C4 cut (9) and the purifier (PUR) obtained from the catalyst cracking device is fed and the C3 / C4 cut (14) An oligomerization step (OLG) to produce a C5-160 deg. C gasoline cut 15 entering, and a third intermediate distillate cut 16 entering the hydrotreater (HDT);

d) a step (HDT) for the complete hydrogenation of the intermediate distillate cut 16 obtained from the oligomerization step, in order to meet market specifications relating to the gas oil.

In a preferred variant of the process according to the invention, the pre-treatment unit (PRET) is of the mild hydrocracking type and functions under the following conditions:

A temperature in the range of 350 ° C to 420 ° C;

A pressure in the range of 8 to 12 MPa;

HSV in the range of 0.3 to 1 h < ^{-1 &} gt ;;

H ₂ / HC in the range of 300 to 800 L / L;

● NiMo, NiCoMo, NiW based catalyst.

In a further preferred variant of the process according to the invention, the pre-treatment unit (PRET) is of the hydrotreating type and functions under the following conditions:

A temperature in the range of 350 ° C to 420 ° C;

A pressure in the range of 4 to 8 MPa;

HSV in the range of 0.5 to 2 h < ^{-1 &} gt ;;

H2 / HC in the range of 150 to 200 L / L;

● NiMo, CoMo, NiCoMo based catalyst.

In a preferred variant of the process of the invention, the catalyst cracking device (FCC) functions under the following conditions:

When the catalyst cracking is carried out in a single riser reactor, the reactor outlet temperature (ROT) is in the range of 450 ° C to 650 ° C, preferably in the range of 470 ° C to 620 ° C, the C / O ratio is in the range of 2 to 20, 4 to 15;

When the reactor is a dropper reactor, the reactor outlet temperature (ROT) is in the range of 480 ° C. to 650 ° C. and the C / O ratio is in the range of 10 to 50, preferably 10 to 30.

In a preferred variant of the process according to the invention, the purification device (PUR) of the ex FCC gasoline feed is characterized in that the nitrogen-containing compound is fractionated by a step of distillation to produce a reduced hard fraction and / Lt; / RTI >

A temperature in the range of 20 ° C to 50 ° C;

A pressure in the range of 5 to 30 bar;

HSV in the range of 0.5 to 4 h < ^{-1 &} gt ;;

● molecular sieve (eg NaX or NaY type).

In a preferred variant of the process according to the invention, the apparatus for the oligomerization of ex FCC gasoline (OLG) functions under the following conditions:

The working temperature is in the range of 100 ° C to 350 ° C, preferably in the range of 150 ° C to 270 ° C;

The working pressure is in the range of 1 to 10 MPa (1 MPa = 10 ⁶ Pascals), preferably in the range of 2 to 6 MPa, more preferably in the range of 4 to 5 MPa;

● Catalysts based on silica-alumina or amorphous silica-alumina or crystalline zeolites.

In another preferred variant of the process according to the invention, the apparatus for the oligomerization of ex FCC gasoline (OLG) functions under the following conditions:

The working temperature is in the range of 180 ° C to 350 ° C, preferably in the range of 200 ° C to 270 ° C;

The working pressure is in the range of 1 to 10 MPa (1 MPa = 10 ⁶ Pascals), preferably in the range of 2 to 6 MPa, more preferably in the range of 4 to 5 MPa;

• Catalyst is made with crystalline zeolite when upgrading the distillate to diesel.

In a preferred variant of the process according to the invention, the apparatus for the oligomerization of ex FCC gasoline (OLG) functions under the following conditions:

The working temperature is in the range of 60 ° C to 200 ° C, preferably in the range of 80 ° C to 180 ° C;

The working pressure is in the range of 1 to 10 MPa (1 MPa = 10 ⁶ Pascals), preferably in the range of 2 to 6 MPa, more preferably in the range of 2 to 4 MPa;

Organic acid resin type catalyst ●.

In a preferred variant of the process of the present invention, the gasoline fraction 15 produced by oligomerization (OLG) is recycled to at least some FCC unit to maximize the production of the middle distillate.

According to the present invention, the entire pre-treated feed contains more than 50% by weight of hydrocarbons having a boiling point of greater than 340 占 폚, and generally more than 80% by volume of boiling compounds at temperatures above 340 占 폚. Preferably, such a typical feed has a boiling point greater than 340 ° C., more preferably greater than 370 ° C., ie, 95% of the compounds present in the feed have boiling points greater than 340 ° C., more preferably greater than 370 ° C. .

The nitrogen content in the treated hydrocarbon feed is generally greater than 500 ppm by weight. Generally, the amount of sulfur ranges from 0.01 wt% to 5 wt%.

The feed for the catalyst cracking unit corresponds to the unconverted fraction of the feed for the pre-treatment unit. It generally contains more than 50% by weight of hydrocarbons having a boiling point of greater than 340 < 0 > C. These feeds contain fewer impurities such as nitrogen-containing or sulfur-containing compounds than the feed to be hydrotreated, which typically has a high hydrogen content in the range of 11% to 15%.

The gasoline cut corresponds to a hydrocarbon cut having a distillation range in the range of 50 ° C to 220 ° C, preferably in the range of 50 ° C to 160 ° C.

The middle distillate cut corresponds to a hydrocarbon cut having a distillation range in the range of 130 占 폚 to 380 占 폚, preferably in the range of 150 占 폚 to 370 占 폚.

The "slurry" cut corresponds to a hydrocarbon cut having an initial boiling point above 380 DEG C, preferably above 360 DEG C.

Specific conditions for the various steps of the method of the present invention are described in more detail below.

1) Pre-processing step (PRET)

According to the present invention, the pre-treatment step is a hydrotreating or hydrocracking catalyst for the hydrotreating of the heavy feed in the fixed bed or boiling layer, typically a solution of a metal from Groups VI and VIII And a device for mild or intense hydrocracking which functions with the aid of a catalyst of the type formed by the feed. Catalysts which also contain zeolite in the support can be conceived. When the pre-treatment reaction is carried out in the fixed bed in a drawer-driven manner, the generally selected working conditions are temperatures in the range 300 ° C. to 450 ° C., preferably 350 ° C. to 430 ° C., 30 to 300 bar, preferably 50 A total pressure in the range of from 180 to 180 bar, an application rate in the range of from 0.1 to 10 h ^-1 , preferably from 0.3 to 5 h ^-1 , and a pressure of from 200 Nm ³ / m ³ to 4000 Nm ³ / m ³ , 2000 Nm is a ratio of hydrogen to hydrocarbon of ³ / m ³ range.

Such an apparatus can be used for hydrodesulfurization, hydrodenitrogenation or hydrogenated decarboxylation of the feed and provides for the conversion of the heavy feed fraction to the product that can be upgraded. This conversion is higher in the case of the hydrogen conversion apparatus than in the case of the hydrotreating apparatus.

The pre-treatment is carried out by a fixed bed or boiling-point catalytic process using high hydrogen pressure, hydrotreating or hydrocracking catalyst.

The pre-treatment section preferably comprises at least one reaction zone containing at least one hydrogenation purification catalyst having a high activity for hydrodesulfurization, hydrodenitrogenation and aromatic hydrogenation.

Pre-treatment catalysts, also referred to as hydrogenation purification catalysts, can be selected from the catalysts commonly used in this field. The hydrogenation purification catalyst may preferably comprise a matrix and at least one hydrogenated dehydrogenating element selected from the group formed by elements from groups VIB and VIII of the element cycle classification.

The matrix may be a compound used alone or as a mixture such as alumina, halogenated alumina, silica, silica-alumina, clay (e.g. selected from natural clay such as kaolin or bentonite), magnesia, titanium oxide, boron oxide, zirconia, aluminum phosphate, Titanium phosphate, zirconium phosphate, coal and aluminate. It is preferred to use all types of alumina known to those skilled in the art, more preferably alumina, for example a matrix containing gamma alumina.

The hydrogenated dehydrogen element may be selected from the group formed by the element from the Group VIB and the non-rare element from Group VIII of the element cycle classification.

Preferably, the hydrogenated dehydrogen element is selected from the group formed by molybdenum, tungsten, nickel and cobalt.

More preferably, the hydrogenated dehydrogenation element comprises at least one element of group VIB and at least one non-rare element of group VIII. Such a hydrogenated dehydrogen element includes, for example, at least one element (Ni, Co) of Group VIII and at least one element (Mo, W) of Group VIB.

Preferably, the hydrogenation purification catalyst also comprises at least one doping element selected from the group formed by phosphorus, boron and silicon deposited on the catalyst. In particular, the hydrogenation purification catalyst may comprise boron and / or silicon, possibly also as phosphorus, as a doping element.

The amount of boron, silicon and phosphorus is generally in the range of 0.1 wt% to 20 wt%, preferably 0.1 wt% to 15 wt%, more preferably 0.1 wt% to 10 wt%.

The hydrogenation purification catalyst may advantageously comprise phosphorous.

These compounds provide, in particular, hydrogenation purification catalysts having two main advantages:

The first advantage is greater ease of manufacture of the catalyst, for example, from solutions based on nickel and molybdenum, especially during impregnation of hydrogenated dehydrogen elements.

A second advantage provided by these compounds is an increase in the hydrogenation activity of the catalyst.

In a preferred hydrogenation purification catalyst, the total concentration of metal oxides from groups VIB and VIII is 2 wt% (preferably 5 wt%) to 40 wt%, preferably 3 wt% (preferably 7 wt%) to 30 By weight and the weight ratio expressed as metallic oxide between the metal (s) from group VIB and the metal (s) from group VIII is in the range of 20 to 1.25, preferably in the range of 10 to 2.

The concentration of phosphorus oxide P ₂ O ₅ may be less than 15 wt%, preferably less than 10 wt%. The preferred support is alumina or silica containing 5-95% SiO ₂ as a mixture of the singly or zeolite-alumina.

In another hydrogenated refinery catalyst comprising boron and / or silicon, preferably boron and silicon, the catalyst generally comprises, by weight, based on the total weight of the catalyst:

From 1% to 99%, preferably from 10% to 98%, more preferably from 15% to 95% of one or more matrices;

3% to 60%, preferably 3% to 45%, more preferably 3% to 30% of one or more Group VIB metals;

Optionally at least one Group VIII metal of from 0 to 30%, preferably from 0 to 25%, more preferably from 0 to 20%;

● 0.1% to 20%, preferably 0.1% to 15%, more preferably

From 0.1% to 10% of boron and / or from 0.1% to 20%, preferably from 0.1% to 15%, more preferably from 0.1% to 10% silicon;

Optionally, 0 to 20%, preferably 0.1 to 15%, more preferably 0.1 to 10%; And

An element optionally selected from one or more VIIA family of 0 to 20%, preferably 0.1 to 15%, more preferably 0.1 to 10%, for example fluorine.

In another hydrogenation purification catalyst, the catalyst comprises:

At least one matrix, preferably alumina, ranging from 1 to 95% by weight (% oxide);

An element from one or more of the groups VIB and non-rare VIII ranging from 5 to 40 wt% (% oxide);

At least one promoter element selected from phosphorus, boron and silicon in the range of 0 to 20% by weight, preferably in the range of 0.1 to 20% by weight (% oxide);

At least one element of group VIIB in the range of from 0 to 20% by weight (% oxide), for example manganese;

At least one element (e.g., fluorine, chlorine) from the VIIA family ranging from 0 to 20 weight percent (% oxide); And

- Elements from one or more VB groups ranging from 0 to 60% by weight (% oxides), such as niobium.

In general, hydrogenation purification catalysts having the following atomic ratios are preferred:

A ratio of Group VIII metal / Group VIB metal atoms in the range of 0 to 1;

A B / Group VIB metal atomic ratio in the range of 0.01 to 3 when B is present;

A Si / VIB group metal atom ratio in the range of 0.01 to 1.5 when Si is present;

A P / VIB group atomic ratio in the range of 0.01 to 1 when P is present; And

The atomic ratio of Group VIIA Group / Group VIB metals in the range of 0.01 to 2, when at least one VIIA Group element is present.

Particularly preferred hydrogenation purification catalysts are NiMo and / or NiW catalysts on alumina or silica-alumina, NiMo on alumina or silica-alumina doped with at least one element contained in the group of atoms formed by phosphorus, boron, / Or NiW catalyst.

Applicants have also developed the catalyst. Examples which may be mentioned are those described in patents FR 2 904 243, FR 2 903 979 and EP 1 892 038.

If a high conversion is desired in the pre-treatment step, a hydrocracking catalyst is used. The hydrocracking catalyst should be a bifunctional catalyst having a hydrogenation phase to hydrogenate the aromatic and an equilibrium between the saturated compound and the corresponding olefin, and an acid phase that can be used to promote hydroisomerization and hydrocracking reactions.

Acid functional groups include supports with a large surface area (typically 100 to 800 m ² / g) with superficial acidity, such as halogenated alumina (especially chlorinated or fluorinated), boron and aluminum, amorphous silica- alumina and zeolites Lt; / RTI >

The hydrogenating functional groups may be protected by one or more metals from group VIII of the elementary cyclic classification, such as iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium or platinum, 0.0 > tungsten < / RTI > and at least one Group VIII metal.

Applicants have also developed a range of such catalysts. Examples of patents which may be mentioned are FR 2 819 430, FR 2 846 574, FR 2 875 417, FR 2 863 913, FR 2 795 341 and FR 2 795 342.

Catalysts that may be mentioned for use in the pre-treatment (PRET) devices of the present invention include series HR 500 (e.g. HR526, HR538, HR548, HR558, HR 562, HR568, and HRK558) (HDK766, HDK776, HDK786) or HYK700 (HYK732, HYK752, HYK762, HYK742).

The apparatus for separating the effluent from the pre-treatment apparatus generally comprises a primary separation of the gas and liquid effluent, a hydrogen recycle section, and a distillation step to separate the various liquid cuts.

At the end of the pre-treatment step (PRET), the resulting unconverted cut contains substantially less sulfur-containing and nitrogen-containing compounds, and a higher hydrogen content than if the feed was not applied to the pre-treatment step . This aspect means that the amount of impurities to be obtained in the effluent from the downstream FCC stage can be substantially reduced.

2) Catalytic cracking step (FCC):

The catalyst cracking apparatus includes a reactor which may be a riser or a dropper type.

When the catalyst cracking is carried out in a single dropper reactor, the reactor outlet temperature (ROT) is in the range of 450 ° C to 650 ° C, preferably 470 ° C to 620 ° C, and the C / O ratio is in the range of 2 to 20, Lt; / RTI >

When the reactor is a dropper type, the reactor outlet temperature (ROT) is in the range of 480 캜 to 650 캜, and the C / O ratio is in the range of 10 to 50.

The flow of the spent catalyst obtained from the FCC reactor is separated from the cracking effluent by any gas-solid separation system known in the art and regenerated in a dedicated regeneration zone.

The effluent from the catalyst cracking reactor is sent to the fractionation zone to produce several cuts defined according to the needs of the purifier.

According to the present invention, the catalyst cracking catalyst consists of a matrix of alumina, silica or silica-alumina with or without a super-stable Y-type zeolite dispersed in the same matrix.

It may also be expected to add ZSM-5 zeolite-based additives in amounts less than 30 wt% of the total amount of catalyst.

Catalysts for FCC reactors typically consist of particles having an average diameter generally in the range of 40 to 140 micrometers, generally in the range of 50 to 120 micrometers.

The catalyst cracking catalyst contains one or more suitable matrices such as alumina, silica or silica-alumina, with or without the presence of Y-type zeolite dispersed in the matrix.

The catalyst may also include one or more zeolites having shape selectivity with one of the following structural types: MEL (e.g. ZSM-11), MFI (e.g. ZSM-5), NES, EUO, FER, CHA (E.g. SAPO-34), MFS, MWW. It may also comprise one of the following zeolites: NU-85, NU-86, NU-88 or IM-5, which also has shape selectivity.

The advantage of this zeolite with shape selectivity is that it has better propylene / isobutene selectivity, i.e. a higher propylene / isobutene ratio in the effluent from cracking.

The proportion of zeolite with shape selectivity relative to the total amount of zeolite can vary depending on the structure of the desired product and the functional group of the feed used. Often, zeolites having a morphology formability of 0.1 wt% to 60 wt%, preferably 0.1 wt% to 40 wt%, especially 0.1 wt% to 30 wt%, are used.

The zeolite (s) can be dispersed in a matrix based on silica, alumina or silica-alumina and the ratio of zeolite (together all zeolites) to the weight of the catalyst is generally in the range of from 0.7 wt% to 80 wt% Preferably in the range of 1 wt% to 50 wt%, more preferably in the range of 5 wt% to 40 wt%.

Where multiple zeolites are used, they may be incorporated into a single matrix or into a plurality of different matrices. The amount of zeolite with shape selectivity in the total inventory is less than 30% by weight.

The catalyst used in the catalyst cracking reactor may consist of a superstable Y-type zeolite dispersed in a matrix of alumina, silica or silica-alumina, to which an additive based on ZSM-5 zeolite is added and a ZSM-5 crystal Is less than 30% by weight.

Devices for the separation of effluent from a catalyst cracking reactor (FCC) generally include a primary fractionation of the FCC effluent, a fraction for gas compression and fractionation, and a distillation for fractionation of various liquid cuts.

In some cases, the HCO cut produced during the FCC (indicated by stream 17 in FIG. 1) may be recycled to the pre-treatment apparatus.

The olefin-based cuts obtained from catalyst cracking consisting of gasoline and C3, C4 olefins having cut points less than 220 DEG C, preferably less than 160 DEG C, can be formed from a number of individual cuts, for example C3 cuts and gasoline cuts, And sent to one or more oligomerization units.

At the end of this step, the resulting gasoline cut retains an equivalent amount of olefin while containing less sulfur-containing and nitrogen-containing compounds than at the end of the FCC alone.

This aspect means that the purification step towards the upstream of the oligomerization step can be reduced or even avoided.

3) Purification step (PUR)

The gasoline feedstock to be treated is sent to a refinery using an adsorbent, such as molecular sieve (e.g. NaX or NaY type), made under the following operating conditions:

A temperature in the range of 20 ° C to 50 ° C;

A pressure of 5 to 30 bar;

HSV in the 0.5 to 4 h ^-1 range.

Examples of adsorbents which can be used in the refining apparatus which may be mentioned are metallic oxides such as alumina, crystalline silico-aluminates such as zeolites (commonly referred to as molecular sieves) or mixtures of such compounds.

Of these compounds, zeolite-based molecular sieves of the faujasite type are preferred. An example is the NaX zeolite marketed by Axens under the trade name SBE 13X.

In certain cases, simple fractionation can also be used to reduce the nitrogen-containing compound and produce an acceptable hard segment in the oligomerization portion.

4) Oligomerization step (OLG)

The goal of the oligomerization step is to oligomerize C3 to C12 olefins, possibly made up of several distinct cuts, such as C3 to C4 cuts and C5-150 DEG C cuts, alone or as a mixture, to form mono- To obtain a mixture of hydrocarbons containing olefins.

Typically, from the C4 olefin an oligomer is obtained that contains up to 30 carbon atoms; Many majority contain from 8 to 20 carbon atoms.

Oligomerization is distinguished from polymerization by the addition of a limited number of molecules. In the context of the present invention, the number of molecules added together ranges from 2 to 20, preferably from 2 to 5, more preferably from 2 to 4, inclusive of the limit value.

However, the oligomerates may contain trace amounts of oligomerized olefins containing more than 10 molecules. Generally, these trace amounts represent less than 5% by weight based on the oligomers formed.

The oligomerization may be carried out in one or more stages using one or more reactors arranged in series or in series and one or more catalysts.

The detailed description of the catalysts and working conditions below can be applied to any of the steps and to the reactor.

Solid oligomerization catalysts operating on a heterogeneous phase are selected from those known in the art. Specific conditions for the various steps of the method of the present invention are described in more detail below.

The oligomerization catalyst used is preferably an acid catalyst based on silica-alumina or amorphous silica-alumina, crystalline zeolite or resin.

The preferred resin is TA801 from AXENS.

The working temperature is in the range of 60 占 폚 to 200 占 폚, preferably 80 占 폚 to 180 占 폚.

The working pressure is in the range of 1 to 10 MPa (1 MPa = 10 ⁶ Pascals), preferably in the range of 2 to 6 MPa, more preferably in the range of 2 to 4 MPa.

Preferred zeolites are those described in patent FR 2 894 850. The working temperature is in the range of 100 캜 to 350 캜, preferably in the range of 150 캜 to 270 캜.

The working pressure is in the range of 1 to 10 MPa (1 MPa = 10 ⁶ Pascals), preferably in the range of 2 to 6 MPa, more preferably in the range of 4 to 5 MPa.

The C5-220 deg. C gasoline cut produced by the oligomerization apparatus, preferably a fraction of the hard C5-160 deg. C gasoline cut, may optionally be recycled to the oligomerization reactor to improve the yield of intermediate distillate.

5) Final Hydrogenation Step (HDT)

The final hydrogenation step (HDT) may be carried out using Ni or NiMo or CoMo supported on a refractory oxide type support (Al, Ti, Si) optionally with one or more promoters (F, P, Ca, Na) NiCoMo and NiW-based partial or complete sulfurization catalysts.

The invention is explained in more detail with the aid of FIG.

The feed 1 is introduced into the pre-treatment unit PRET together with the hydrogen composition 1b.

This treatment in the presence of hydrogen is intended to modify the olefin to the alkane; This can be done using any catalyst known in the art and associated with operating conditions. In particular, Ni and Mo based sulfiding catalysts such as HR 306, HR 406 or HR 506 from AXENS can be used. Such catalysts are operated in gaseous and high temperature, at 350-420 < 0 > C and high hydrogen content.

Catalysts based on Ni and S, such as the LD series of LD series, AXENS, 241, 341 and 541, which are working in liquid phase at low temperatures (150-180 DEG C) can also be used and are preferred.

Typically, in order of increasing molecular weight, the following is discharged from the pre-treatment apparatus PRET:

● Gasoline cut (3);

Cuts (4) referred to as "heavy distillates ";

Not switched ● (5).

Cut 5 is then sent to the catalyst cracking unit (FCC) where the phosphorus is discharged in the order of increasing molecular weight:

● a hydrogen (H _2), methane and possibly the dry gas cut consisting of ethane, ethylene (7);

Cut C3 (8) formed by a propylene-enriched, hydrocarbon molecule containing three carbon atoms;

A C4 cut (9) formed by a butene-rich hydrocarbon molecule containing four carbon atoms;

● Gasoline cut (10);

A cut 11 referred to as "intermediate distillate ";

A cut 12, referred to as a "slurry" cut, added to the fuel pool;

● In some cases, the HCO cut can be vented and recirculated to the pre-treatment (2).

The gasoline cut 10 is then optionally refined in a purifier (PUR).

The refined gasoline cut 10 'is then sent with the cuts 8 and 9 as feed to an oligomerization apparatus OLG.

Three cuts are ejected from this oligomerization apparatus (OLG): < RTI ID = 0.0 >

Cuts 14, referred to as raffinates, corresponding to unconverted olefins and paraffins from the C3 (8) and C4 (9) feeds;

A gasoline cut 15 corresponding to the fraction of oligomers formed from paraffins and cuts (8) and (9) contained in the cut (10 ');

● Cut a middle distillate corresponding to a heavy oligomer formed from cuts (8), (9) and (10 ').

The intermediate distillate cut is sent to the hydrogenation unit (HDT) to comply with commercial specifications.

Example

Applicants will now provide the following two embodiments to illustrate the improved performance of the method of the present invention in comparison to prior art methods.

Example 1 (Prior art): FCC + oligo reference case

This first embodiment constitutes a basic case and corresponds to an oligomerization device after monolizer FCC device.

The FCC unit has a capacity of 40000 BPSD, or 230 t / hr, (BPSD is abbreviation for barrel per day) and processes a straight run VGO, i.e., vacuum gas oil, obtained directly from a vacuum distiller .

The catalyst cracking apparatus was operated using a catalyst system composed of silica-alumina.

The operating conditions and feed characteristics for the FCC unit are shown in Tables 1 and 2 below, respectively.

Key characteristics of VGO feed Density at 15 ° C 0.9149 Base nitrogen mg / kg 417 nitrogen % 0.127 sulfur % 1.22 Hydrogen weight% 12.3

Working conditions for FCC in Example 1 Example 1 Capacity of FCC unit, VGD supply Barrel / d 40 000 Flow rate of VGO feed t / h 230 Riser outlet pressure bar g 1.4 Riser outlet temperature ℃ 550 Feed pre-treatment temperature ℃ 220 The ratio of the mass flow rate of the catalyst to the feed flow rate 6.2

Under these conditions, yields for the product remaining in the catalyst cracking apparatus for the feed are given in Table 3 below.

The yield of the product from the catalyst cracking of Example 1 weight% Ex FCC
Basic case Dry gas 3.9 C3 cut 8.9 C4 cut 12.5 Gasoline (IBP-160 ℃) 36.4 Heavy gasoline (160 - 220 ℃) 9.7 The middle distillate (220 ° C - 360 ° C) 15.7 "Slurry" (360 < 7.4 Cork 5.5 gun 100

IBP-160 deg. C Gasoline had an olefin content of 47.6 wt% and a nitrogen content of 50 wt ppm.

The sulfur content was 800 ppm by weight.

A C3 cut composed mainly of propylene and propane, and a C4 cut consisting mainly of butene and butane, and a gasoline cut (IBP-160 占 폚) were then sent to the oligomerization unit.

Because of the presence of sulfur and nitrogen, the purification section was placed upstream of the oligomerization apparatus. It consisted of a mass of NaX molecular sieve placed as a fixed bed and functioned at a temperature of 25 캜 using one layer of working mode and one layer of regeneration mode.

Table 4 shows the working conditions of the tablet and oligomerization apparatus.

Working Conditions for Tablet and Oligomerization Apparatus Example 1 The flow rate of the feed (C3-160 DEG C) (t / h) 133 refinery Amount of NaX molecular sieve t 22.1 Oligomerization device Temperature ℃ 160-250 * pressure bar g 50 Amount of catalyst t 250 IBP 811 catalyst (Axens) * Temperature gradually increased to maintain catalyst activity

Under these conditions, the yields of the products obtained in the catalyst cracking apparatus and the oligomerization apparatus compared to the feed entering the catalyst cracking apparatus are given in Table 5 below:

The yield of the product obtained from the catalyst cracking and oligomerization series of Example 1
weight% origin Example 1 Prior Art Dry gas FCC 3.89 Raffinate Oligomerization 4.27 Gasoline (IBP-220 ℃) Oligomerization and FCC 33.95 The middle distillate (220 ° C - 360 ° C) FCC and oligomerization 45.00 Slurry (360 < 0 > C + FCC 7.40 Cork FCC 5.49 gun 100

The intermediate distillate cut obtained from the oligomerization was then hydrogenated: at 160 ° C under 50 bar of hydrogen and at a flow rate of gaseous hydrogen for a flow rate of HSV of 1.5 h ^-1 and a liquid feed of 100 NL / L , And hydrogenation using a nickel sulphide catalyst (LD 541).

Thus, sending C3, C4 and gasoline cuts to the oligomerization step can increase the yield of the intermediate distillate to 29.3 wt%.

Example 2 (According to the Invention): Mild Hydrocracking Apparatus, followed by Continuation of FCC Apparatus with Device for Oligomerization of C3, C4 Olefin and Gasoline

In Example 2, the FCC unit functioned under the same conditions as described for Example 1, but this time the FCC unit was preceded by the same feed as in Example 1, i.e., the mild hydrocracking unit fed with DC VGO.

The operating conditions for the mild hydrocracker are shown in Table 6.

Working conditions for a mild hydrocracking apparatus - Example 2 Mild hydrocracking unit Example 2 Flow rate of VGO feed t / h 230 Temperature ℃ 365 HSV h ^-1 1.0 H2 / HC L / L 400 pressure bars g 70

Under these conditions, the yield of the product left in the mild hydrocracking step for the feed is given in Table 7 below.

The product yield from the mild hydrocracking apparatus of Example 2 weight% End point Gasoline (IBP-220 ℃) 2.0 product Middle distillate
(220 캜 - 360 캜) 10 product Hydrogen treated VGO 78 FCC gun 100

At the end of the catalyst cracking step, the yield of the organism for the hydrotreated VGO feed is changed as described in Table 8 below:

The yield of the product obtained at the end of the catalyst cracking step of Example 2 weight% Dry gas 2.37 C3 cut 9.92 C4 cut 14.23 Gasoline (IBP-160 ℃) 42.13 Heavy gasoline (160-220 ° C) 10.15 The middle distillate (220 ° C - 360 ° C) 12.14 Slurry (360 < 0 > C + 4.45 Cork 4.61 gun 100

IBP-160 캜 Gasoline had an olefin content of 44.0% and a nitrogen content of 20 ppm by weight. The sulfur content was 150 ppm.

A C3 cut composed mainly of propylene and propane, and a C4 cut composed mainly of butene and butane, and a gasoline cut (IBP-160 占 폚) were then sent to the oligomerization unit.

The purification and oligomerization conditions are given in Table 9 below:

Working Conditions for Tablet and Oligomerization Apparatus The flow rate of the feed (C3-160 DEG C) (t / h) 119 refinery Amount of NaX molecular sieve t 8.8 Oligomerization device Temperature ℃ 160-250 * pressure bar g 50 Amount of catalyst IBP 811 catalyst (Axens) t 240 * Temperature gradually increased to maintain catalyst activity.

The lower amount of impurities (nitrogen and sulfur) in the feed means that the amount of molecular sieve used in the purification apparatus disposed upstream of the oligomerization apparatus has been very substantially reduced from 22.1 to 8.8 tons.

Accordingly The size of the sieve refinement apparatus is greatly reduced.

For the feed entering the mild hydrocracking unit, the yields of products obtained from mild hydrocracking, catalyst cracking and oligomerization of C3 =, C4 =, gasoline cuts are given in Table 10 below:

The yield of the product obtained from the mild hydrocracking and catalyst cracking and oligomerization successes of Example 2 weight% origin Example 2 According to the invention Dry gas FCC 1.85 Raffinate Oligomerization 4.40 Gasoline (IBP-220 ℃) Mild hydrocracking and oligomerization and FCC 32.65 The middle distillate (220 ° C - 360 ° C) Mild hydrocracking and FCC and oligomerization 54.03 Slurry (360 < 0 > C + FCC 3.47 Cork FCC 3.60 gun 100

The intermediate distillate cut was then hydrogenated under the same conditions as in Example 1.

The succession of the mild hydrocracking (PRET) and (FCC) devices and the oligomerization device (OLG) significantly improved the amount of intermediate distillate produced. In the basic case, this intermediate distillate production represented 45.0 wt.%, In contrast to 54.03 wt.% (I.e., an increase of 9.03%) in the arrangement of the present invention.

The gasoline cut itself did not increase due to pre-treatment, and actually dropped from 33.95% by weight in the basic case to 32.65% by weight and decreased by 1.30%.

The selectivity (intermediate distillate / gasoline ratio) for the middle distillate to gasoline has thus been improved from 1.32 to 1.65 (i.e. a relative gain of 25% by weight), which can be considered in terms of changes in the fuel market Improvement.

Claims (9)

A method for producing a middle distillate from a heavy gas oil or heavy feed (1) of an atmospheric residue type using the following four steps:
- a) carried out in a hydrocracking or hydrotreating device to reduce the amount of sulfur-containing and nitrogen-containing impurities in the feed, and the diolefin content thereof, and having a C5-160 ° C gasoline cut (3) (PRET) which yields a first intermediate distillate cut (4) having a distillation range of not less than 5 DEG C and a fraction (5) which is referred to as the unconverted fraction having substantially the same distillation range as the incoming heavy feed, ;
b) cut 7, C3 cut 8, C4 cut 9, C5-160 deg. C gasoline cut 10, and second intermediate distillate 10, referred to as dry gas cuts, For the catalytic cracking (FCC) of the unconverted fraction (5) obtained from said pre-treatment step (PRET), producing a cut (11), said gasoline cut (10) being sent to a purifier ;
c) a gasoline cut 10 'obtained from the cut C3 (8), C4 cut (9) and purifier (PUR) obtained from the catalyst cracking device is fed and the C3 / C4 cut 14, An oligomerization step (OLG) to produce a C5-160 deg. C gasoline cut (15) entering the first intermediate distillate cut (16) and a third intermediate distillate cut (16) sent to the hydrotreater (HDT);
d) a step (HDT) for the complete hydrogenation of the intermediate distillate cut 16 obtained from the oligomerization step to satisfy market specifications relating to the gas oil. The method of claim 1, wherein the pre-treatment apparatus (PRET) is of the mild hydrocracking type and functions under the following conditions: a medium distillate from a vacuum gas oil or a heavy-
A temperature in the range of 350 ° C to 420 ° C;
A pressure in the range of 8 to 12 MPa;
HSV in the range of 0.3 to 1 h < ^{-1 &} gt ;;
H ₂ / HC in the range of 300 to 800 L / L;
● NiMo, NiCoMo, NiW based catalyst. The method according to claim 1, wherein the pre-treatment apparatus (PRET) is of a hydrotreating type and functions under the following conditions: a medium gas distillate from a vacuum gas oil or heavy-
A temperature in the range of 350 ° C to 420 ° C;
A pressure in the range of 4 to 8 MPa;
HSV in the range of 0.5 to 2 h < ^{-1 &} gt ;;
H ₂ / HC in the range of 150 to 200 L / L;
● NiMo, CoMo, NiCoMo based catalyst. The method of claim 1, wherein the catalytic cracking unit (FCC) functions under the following conditions: a medium gas distillate from a vacuum gas oil or a heavy feed of medium pressure residual type (1)
When the catalyst cracking is carried out in a single riser reactor, the reactor outlet temperature (ROT) is in the range of 450 ° C to 650 ° C and the C / O ratio is in the range of 2 to 20;
When the reactor is a dropper reactor, the reactor outlet temperature (ROT) is in the range of 480 ° C. to 650 ° C. and the C / O ratio is in the range of 10 to 50. The process according to claim 1, wherein the purifying device (PUR) is a vacuum gas oil or a gas phase oil, comprising a distillation step to produce a reduced hard fraction of the nitrogen-containing compound and / or fractionation by adsorption to the molecular sieve under the following conditions: A method for producing a middle distillate from a heavy feed of medium pressure residual type (1)
A temperature in the range of 20 ° C to 50 ° C;
A pressure in the range of 5 to 30 bar;
HSV in the range of 0.5 to 4 h < ^{-1 &} gt ;;
● molecular sieve. The method of claim 1, wherein the apparatus (OLG) for oligomerization functions under the following conditions: a medium gas distillate from a vacuum gas oil or a heavy feed of medium pressure residual type (1)
● the operating temperature is in the range of 100 ° C to 350 ° C;
The working pressure is in the range of 1 to 10 MPa (1 MPa = 10 ⁶ Pascals);
● Catalysts based on silica-alumina or amorphous silica-alumina or crystalline zeolites. The method of claim 1, wherein the apparatus (OLG) for oligomerization functions under the following conditions: a medium gas distillate from a vacuum gas oil or a heavy feed of medium pressure residual type (1)
● Working temperature is in the range of 180 ° C to 350 ° C;
The working pressure is in the range of 1 to 10 MPa (1 MPa = 10 ⁶ Pascals);
● Crystalline zeolite-based catalysts for upgrading distillates to diesel. The method of claim 1, wherein the apparatus (OLG) for oligomerization functions under the following conditions: a medium gas distillate from a vacuum gas oil or a heavy feed of medium pressure residual type (1)
● the operating temperature is in the range of 60 ° C to 200 ° C;
The working pressure is in the range of 1 to 10 MPa (1 MPa = 10 ⁶ Pascals);
Organic acid resin type catalyst ●. 9. A process according to any one of claims 6 to 8, wherein the gasoline fraction (15) produced by oligomerization (OLG) is recycled to at least some FCC unit to maximize the production of the middle distillate.

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