EP2707461A2

EP2707461A2 - Method for the production of diesel or kerosene cuts from an olefin feed mainly having between 4 and 6 carbon atoms

Info

Publication number: EP2707461A2
Application number: EP12713204.1A
Authority: EP
Inventors: Pierre Alain BREUIL; Nicolas Cadran; François Hugues; Vincent Coupard
Original assignee: IFP Energies Nouvelles IFPEN
Current assignee: IFP Energies Nouvelles IFPEN
Priority date: 2011-05-12
Filing date: 2012-03-13
Publication date: 2014-03-19
Also published as: WO2012153010A3; WO2012153011A2; HUE030396T2; EP2707462B1; FR2975104A1; FR2975104B1; WO2012153010A2; WO2012153011A3; FR2975103A1; EP2707462A2; FR2975103B1

Abstract

The invention relates to a method for the production of a diesel and middle distillate cut from an olefin feed having between 4 and 6 carbon atoms, said method including a first purification step performed on a resin, followed by an oligomerisation step performed on an acid catalyst.

Description

PROCESS FOR PRODUCING KEROSENE OR GASOLINE CUT FROM AN OLEFINIC CHARGE HAVING A MAJORITY OF 4 TO 6 CARBON ATOMS

FIELD OF THE INVENTION

The present invention is in the field of refining processes for converting an olefinic fraction having predominantly 4 to 6 carbon atoms in a so-called middle distillate cut having predominantly 10 to 20 carbon atoms.

This middle distillate cut may be a kerosene cut or a diesel cut.

The present invention uses a purification step for removing nitrogen compounds contained in the feed followed by an oligomerization step to produce the desired kerosene or diesel fuel cut. EXAMINATION OF THE PRIOR ART

The prior art in the field of kerosene cut production is quite extensive, but it is possible to retain the patent EP 1 396 532 which describes a process for upgrading a liquid hydrocarbon feedstock comprising the following steps:

a) separating from said hydrocarbon feedstock a fraction (01) essentially comprising compounds containing 5 carbon atoms, at least 2% by weight of pentenes,

b) bringing said fraction (01) into contact with a hydrocarbon cut (02) comprising at least partly hydrocarbons having a number of carbon atoms of between 6 and 10, of which at least 2% by weight of olefins, in the presence of at least one catalyst promoting the dimerization and alkylation reactions of the species present in the mixture resulting from said contacting,

c) a separation of the effluents from step b) into at least two slices of which:

- a gasoline cut (a) whose upper distillation point is less than 100 ° C and comprising the majority of reagents unreacted and,

a kerosene fraction (β) with a distillation range of between 100 ° C. and 300 ° C. comprising the majority of the products resulting from the alkylation and dimerization reactions.

This patent does not describe any pretreatment step, in particular purification of the feedstock (01).

Patent FR 2 887 555 describes a process for preparing a diesel cut from a C 2 -C 12 olefinic cut comprising the following steps:

1) oligomerization of a C2-C12, preferably C3-C7 and even more preferably C3-C5 olefinic hydrocarbon fraction, 2) a separation of the product mixture obtained in step 1), in three sections, including an intermediate section with a final boiling point of between 200 and 220 ° C.

3) an oligomerization of the intermediate section carried out in the presence of a C4 and / or C5 olefinic hydrocarbon fraction.

This process therefore uses a very broad olefinic fraction as filler and uses two distinct oligomerizations. It does not mention the possibility of a pretreatment of said charge, including purification against any nitrogen compounds contained in said charge.

The patents FR 2 871 167 and FR 2 871 168 describe processes for producing diesel fuel cut from gasoline cuts comprising a first step of separation of the normal and isoolefins, the oligomerization step relating only to the normal olefins.

The process according to the present invention does not require any prior separation of the normal and iso olefins.

Finally, the patent application filed under No. 10 / 03,559 describes a complex process using an olefinic C4 to C10 cut to which is added an LPG cut and a BTX cut (abbreviation of benzene, toluene and xylenes) allowing perform an alkylation reaction of the olefins on the BTX cut.

The process according to the present invention does not use any alkylation step and therefore does not require any BTX-type cutting.

SUMMARY DESCRIPTION OF THE FIGURES

FIG. 1 represents a diagram of the process according to the invention using a single oligomerization unit preceded by a step of purification of the charge on resins. SUMMARY DESCRIPTION OF THE INVENTION

The process according to the present invention uses a single oligomerization unit.

The process can be defined as a process for producing an average distillate cut having predominantly from 10 to 22 carbon atoms from an olefinic feed having predominantly between 3 and 8 carbon atoms, and preferably between 4 and 6 carbon atoms. carbon, comprising the following sequence of steps:

1) a step of purifying the charge on a resin intended to remove the nitrogenous compounds, and operating under the following operating conditions: - temperature between 20 ° C and 150 ° C, and preferably between 40 ° C and 100 ° C,

pressure between 10 and 30 bars (1 bar = 10 ⁵ pascal)

- VVH between 0.5 and 1 h-1.

2) an oligomerization step of the effluents resulting from the purification step carried out at a temperature of between 120 ° C. and 250 ° C. on an amorphous aluminoxidic type catalyst, or at a temperature of between 150 ° C. and 300 ° C. C on a zeolite catalyst,

3) a step of separating the effluents from the oligomerization stage into at least two sections, a gasoline section having up to 10 carbon atoms, a middle distillate section (kerosene or diesel section) having from 10 to 22 carbon atoms; carbon,

4) a step of total hydrogenation of the middle distillate cut leading to a kerosene or diesel cut to the market specifications. DETAILED DESCRIPTION OF THE INVENTION

The detailed description of the process according to the invention is based on FIG.

The feed consists of a section of olefinic hydrocarbons containing from 3 to 8 carbon atoms, preferably from 4 to 6 carbon atoms. It contains from 20% to 100%) of olefins, preferably from 20% to 80% of olefins, and more preferably from 40% to 60% of olefins.

It can come from a fluidised bed catalytic cracking unit or from a naphtha steam cracking unit, or from an alcohol dehydration unit or from a Fischer-Tropsch synthesis unit or from other available sources. from refining or petrochemical units.

The filler (1) is introduced into a purification unit (PUR) which contains an acidic resin for example of polystyrene-divinylbenzene functionalized with sulphonic groups, as described in the international patent application filed under the number WO 2011/135206. .

The density of the acidic sites is greater than 0.5 meq / gram, preferably greater than 1 meq / gram and more preferably between 1 and 5 meq / gram (meq is the abbreviation of milliequivalent). The Amberlyst products sold by Rohm and Haas are representatives of this family of compounds and may by way of non-limiting example, be used in the context of the present invention.

The operating conditions of the purification unit (PUR) are as follows:

- Temperature between 20 ° C and 150 ° C, and preferably between 40 ° C and 100 ° C,

- Pressure between 10 and 30 bar (1 bar = 10 ⁵ pascal)

- VVH between 0.5 and 1 h -1.

The VVH or space velocity is defined as the ratio of the volume flow rate of charge to be treated on the volume of resin contained in the purification unit.

This purification unit is mainly intended to eliminate the nitrogenous compounds contained in the feed and which constitute poisons with respect to the catalysts used in the downstream oligomerization unit.

The effluent (2) leaving the purifying unit (PUR) is optionally sent to a separation unit (DIST1) for extracting a gasoline cut (3 ') with a good octane number and which can thus join the gasoline pool (POOL). Part of this species (3 ') can also be directed to the oligomerization unit (OLG).

The effluent (2) from the purification unit (PUR), or the effluent (3) from the separation unit (DIST1) when it exists, is sent to the oligomerization unit (OLG ) which operates under the following operating conditions:

temperature between 120 ° C. and 250 ° C., if the catalyst used is a silica-alumina type catalyst, or

- Temperature between 150 ° C and 300 ° C, if the catalyst used is a zeolite catalyst. '

The effluent (4) of the oligomerization unit (OLG) is separated in a distillation column (DIST2) in at least 4 sections:

a head section (6) called raffinate, corresponding to an LPG type cut,

an intermediate section (7) which corresponds to a species with a carbon number of between 5 and 10,

- a bottom cut (8) called middle distillate of number of carbon atoms between 10 and 22 which is sent to the total hydrogenation unit (HT) to form the kerosene or gas oil to commercial specifications, - A cut said residue (9) of initial boiling point greater than 280 ° C which joins the fuel pool of the refinery.

The oligomerization catalyst, when it is of amorphous silico aluminate type, may be chosen from silica-aluminas or siliceous aluminas, and preferably sliculated aluminas. The weight ratio SiO 2 / Al 2 O 3 is between 0.1 and 10, and preferably between 0.2 and 1.

A preferred catalyst is that marketed by AXENS under the name IP 811 ™.

The oligomerization catalyst, when based on zeolite, preferably comprises at least one zeolite selected from the group consisting of aluminosilicate zeolites having an overall Si / Al atomic ratio greater than 10, and a pore structure 8, 10 or 12MR.

It is preferably constituted by a zeolite selected from the group consisting of aluminosilicate zeolites having an overall Si / Al atomic ratio greater than 10 and a pore structure of 8, 10 or 12MR.

Said zeolite is more preferably selected from the group consisting of zeolites: ferrierite, chabazite, zeolites Y and US-Y, ZSM-5, ZSM-12, NU-86, mordenite, ZSM-22, NU-10, ZBM -30, ZSM-11, ZSM-57, ZSM-35, IZM-2, ITQ-6 and IM-5, SAPO, taken alone or in admixture. Very preferably, said zeolite is selected from the group consisting of ferrierite zeolites, ZSM-5, Mordenite and ZSM-22, taken alone or as a mixture. Even more preferably, the zeolite used is ZSM-5.

EXAMPLES ACCORDING TO THE INVENTION

The following 4 examples illustrate the invention without limiting its scope.

All examples are obtained from laboratory experiments.

Example 1: Charge C5-C6 (LCN)

The filler is a light gasoline that comes from an FCC unit, under the name LCN (Light Cut Naphta).

It is composed in mass percentages of:

1.9% butanes and butenes (0.4 and 1.5% respectively); 25% iso-pentenes; 24% n-pentenes; 28% pentanes; 11% hexenes and 7.0% hexanes.

The charge has a density of 0.6548.

It also contains organic nitrogen compounds totaling a content of 11.6 ppm by weight expressed as elemental nitrogen and 15 ppm by weight of elemental sulfur.

Step a) Purification

28 grams of resin or Amberlyst ™ 36WET dried by washing with methanol and then under vacuum at 70 ° C. for 16 hours) are placed in a fixed bed reactor

The raw feed is injected into the reactor, from bottom to top, at a rate of 36 g / h corresponding to a VVH (hourly space velocity) of ¹ hr ^-1 .

The pressure is maintained at 30 effective bars (1 bar = 10 ⁵ pascal), and the temperature is gradually raised between 60 ° C. and 110 ° C., in order to keep the conversion of the isoolefins in C5 constant between 85% and 90%. .

An average increase of 10 ° C every 200 hours is necessary to achieve this goal. Under these conditions, the conversion of n-olefins to C5 is between 10 and 20%. The analysis of the elemental nitrogen at the outlet, on the total effluent, shows a value of less than 1 ppm by weight.

After distillation of a portion of the effluent from purification step a), the distribution, as well as the properties of the gasoline cut 15-150 ° C. (60% by weight), is as follows:

Density = 0.6625

Number of bromine = 83 g / 100g

MAV <0.5 mg / g

S <1 ppm weight

Research octane number (IOR) = 95.5

Step b) oligomerization on silico-aluminate catalyst

The remaining portion of the total effluent of purification step a) is collected and fed to the oligomerization reactor containing 60 grams of the IP 811 ™ oligomerization catalyst manufactured by AXENS.

The charge of the oligomerization reactor is composed of the hydrocarbon effluent obtained after conversion of the charge C5-C6 on Amberlyst ™ 36WET resin during the purification step a).

It contains 2% butane + butenes; 4% isopentenes, 21% n-pentenes, 28% pentanes, 12% hexenes + hexanes and 33% C7 + olefins The oligoménsation step is operated in the presence of cata IP 811 at a pressure of 5 MPa and a VVH of 0.5 h-1 between 160 ° C and 200 ° C. An average increase of ° C per 100 h is necessary to keep the conversion of n-pentenes constant around 70%.

Under these conditions, the conversion of iso-olefins is greater than 95%.

The effluent of oligoménsation stage b) is separated by distillation into four sections:

1) a C4- cut (5% weight)

2) a section 15-140 ° C, (45% by weight) constituting the light gasoline cut, whose research octane number is: 95

3) a cut 140-280 ° C, (40% weight) which is then hydrogenated. The hydrogenation is carried out with a nickel catalyst at 180 ° C. under 50 bar of hydrogen with a VVH of 0.5 and a hydrogen flow rate of 50 NL / h and a loading rate of 48 g / h.

The olefin content observed after hydrogenation is very low (bromine number <0.8 g / 100 g). ) to provide a kerosene cut, the characteristics of which are as follows:

Smoke point: 40 mm,

Flash point: 45 ° C,

Crystallization point: <-65 ° C,

Density: 0.770

4) 280+ residue (10% weight) Example 2 C5-C6 CLCN feedstock

The operating conditions of purification step a) are carried out with the same filler and the same resin as in Example 1: 60 ° C., at 30 bars, kept unchanged for 500 hours.

The initial conversion of the iso-olefins is 80%), progressively decreasing, and that of the normal olefins is less than 5%.

The analysis of the total nitrogen on the total effluent shows a value of less than 1 ppm by weight. The conditions of the oligomerization step b) are as follows:

Catalyst IP 811,

Hourly weight speed of 0.5 h -1,

Pressure 50 bar,

Increased temperature gradually between 160 ° C and 200 ° C to maintain constant conversion of normal olefins, around 70%. An average increase of 2 ° C / 100 h is necessary to achieve this goal. Under these conditions, the conversion of the iso-olefins is greater than 95%.

Example3: Charge C4 ex FCC + C5-C6 (LCTND

The charge is composed of an LCN cut mixture described in Example 1 and a C4 cut from an FCC unit.

It contains: 16.1% n-butenes; 5.7% i-butenes; 13.9% butanes; 16.7% i-pentenes, 15.6% n-pentenes; 17.7% pentanes; 7.2% hexenes and 4.6% hexanes. Its density is 0.6312.

It also contains organic nitrogen compounds totaling a content of 7.6 ppm by weight expressed as elemental nitrogen and 14 ppm by weight of elemental sulfur.

StepΣL): purification on sulfonic resin.

28 grams of Amberlyst ™ 36WET resin dried by washing with methanol and then under vacuum at 70 ° C. for 16 hours are placed in a fixed bed.

The feedstock is injected into the reactor from bottom to top at a rate of 32 g / h (corresponding to _a. WH lh ^"1).

The pressure is maintained at 30 bars effective and the temperature is gradually increased between 80 ° C and 140 ° C, in order to maintain constant conversion of the iso-olefins C5 between 85% and 90%. The conversion of isobutene is greater than 95%.

An average increase of 10 ° C every 200 hours is necessary to achieve this goal. Under these conditions, the conversion of n-olefins is between 20% and 30% for n-C4 and between 10% and 20% for n-C5.

The analysis of the elemental nitrogen at the outlet, on the total effluent, shows a value of less than 1 ppm by weight.

The distribution on a portion of the effluent of purification step a is the following after distillation in 2 sections:

a 15-150 ° C section (67% by weight) constituting the light petrol cut, the characteristics of which are as follows:

Density = 0.6845;

Bromine number = 82 g / 100g;

MAV <0.5 mg / g; S <1 ppm by weight;

Research octane number (IOR) = 96.

a 150+ cup (33% by weight) which is then hydrogenated to provide a kerosene cut. The hydrogenation is carried out with a nickel catalyst at 180 ° C. under 50 bar of hydrogen with a WH of 0.5 and a hydrogen flow rate of 50 NL / h and a feed rate of 48 g / h. The olefin content observed after hydrogenation is very low (bromine number <0.8 g / 100 g). The characteristics of the kerosene cut obtained are as follows:

Cloud point = -48 ° C;

Cetane number = 23;

Flash point = 47 ° C;

Smoke point = 38 mm;

Crystallization point <-65 ° C;

Pour point <-48 ° C.

Density: 0.775

Step b) oligomerization on silico-aluminate catalyst

The charge of the oligomerization reactor is composed of the hydrocarbon effluent obtained after transformation of a C4-C5-C6 load on Amberlyst ™ 36WET resin during the previous step. It contains 14% butanes, 12% butenes; 3% isopentenes, 13% n-pentenes, 17% pentanes, 4% hexenes; 5% hexanes and 32% C7 + olefins

The oligomerization step operates in the presence of the catalyst IP 811 and at a temperature of 170 ° C., under a pressure of 5 MPa, and at a weight hourly weight of 0.5 h -1, so as to obtain an average conversion of C4-C5-C6 olefins around 80%. After distillation, the following cuts are obtained:

a C4- cut (18% by weight)

a section 15-140 ° C, (44% by weight) constituting the light gasoline cut, whose research octane number is 96,

a section 140-280 ° C (28% by weight) which is then hydrogenated to provide a kerosene cut, the characteristics of which are as follows:

Smoke point: 38 mm;

Flash point: 48 ° C; Crystallization point: <-65 ° C

Density: 0.778

a residue 280+ (10% by weight) Example 4: Charge C4 ex FCC + C5-C6 (CN)

Step a): purification on sulfonic resin.

This step is carried out with the same load and the same operating conditions as in Example 3.

The total effluent is collected to be used in the oligomerization step b)

Step b): oligomerization on zeolitic catalyst

Preparation of the zeolite catalyst used in the present example:

Zeolite ZSM-5 is a commercial zeolite of Si / Al ratio equal to 40 in its NH4 + form.

The catalyst is prepared by mixing the ZSM-5 zeolite with a SB3-type alumina supplied by CONDEA.

The kneaded paste is then extruded through a die of diameter 1.4 mm. The extrudates thus obtained are dried at 120 ° C. for 5 hours and then calcined in dry air at 550 ° C. for 2 hours in air. The weight content of zeolite is 60% by weight.

The charge of the oligomerization reactor is composed of the hydrocarbon effluent from step a.

It contains 14% butanes, 12% butenes; 3% isopentenes, 13% n-pentenes, 17% pentanes, 4% hexenes; The oligomerization step b) operates in the presence of the zeolite catalyst C2 described above at a temperature of 235 ° C., at a pressure of 5 MPa and at an hourly weight speed. from 1h-1.

The conversion of C4 olefins is 93%, those of C5 olefins 91%.

The distribution of the products leaving the oligomerization reactor is then as follows:

a C4- cut (l 5% by weight) a section of 15-150 ° C (26% by weight) constituting the light gasoline cut, whose research octane number (IOR) is 97,

a section 150 ° C.- 350 ° C. (57% by weight) which is then hydrogenated (conditions identical to those described above) to provide a diesel cut, the characteristics of which are:

cetane number: 50; Flash point: 57 ° C; Crystallization point: <-65 ° C; density: 0.785

Claims

A process for producing an average distillate cut having predominantly 10 to 22 carbon atoms from an olefinic feed having predominantly 4 to 6 carbon atoms, and comprising the following steps:

1) a purification step (PUR) of the charge on an organic resin, intended to remove nitrogen compounds from the charge,

2) an oligomerization stage (OLG) effluents from the purification step carried out at a temperature between 120 ° C and 250 ° C on an amorphous catalyst silico aluminate type, or at a temperature between 150 ° C and 300 ° C on a zeolitic catalyst,

4) a step of total hydrogenation of the middle distillate cut to obtain a kerosene or gas oil to the market specifications.

Process for the production of a medium distillate cut with predominantly 10 to 22 carbon atoms from a predominantly C 4 -C 6 olefinic feedstock according to claim 1, wherein the purification step is carried out on an acidic organic resin, a temperature between 20 ° C and 150 ° C, and preferably between 40 ° C and 100 ° C, at a pressure between 10 and 30 bar, and with a VVH between 0.5 and 1 h-1.

Process for the production of a medium distillate cut having predominantly from 10 to 22 carbon atoms from a C 4 -C 6 olefinic feedstock according to Claim 1, in which a petrol cut having from 8 to 8 is extracted from the purification step. at 12 carbon atoms, maintaining a minimum of 10% of said gasoline cut in the effluents of said purification step to feed the oligomerization step. Process for the production of a medium distillate cut having predominantly from 10 to 22 carbon atoms from an olefinic feed having predominantly from 4 to 6 carbon atoms according to claim 1, wherein the oligomerization step (OLG) is carried out on a silico-aluminate catalyst in which the SiO 2 / Al 2 O 3 mass ratio is between 0.1 and 10, and preferably between 0.2 and 1.

Process for the production of an average distillate fraction having predominantly from 10 to 22 carbon atoms from an olefinic feed having predominantly 4 to 6 carbon atoms according to claim 1, wherein the oligomerization step (OLG) is carried out on a zeolite-based catalyst, the zeolite used being selected from the group consisting of: ferrierite, ZSM-5, ZSM-12, NU-86, mordenite, ZSM-22, NU-10, ZBM-30, ZSM-11, ZSM-57, ZSM-35, IZM-2, ITQ-6 and IM-5.

Process for the production of a medium distillate cut having predominantly from 10 to 22 carbon atoms from an olefinic feed having predominantly from 4 to 6 carbon atoms according to claim 1, wherein the oligomerization step (OLG) is carried out on a zeolite-based catalyst, the zeolite used being ZSM-5.