CA2194547C - Jet fuel and method for producing same - Google Patents

Abstract

A jet fuel with the following characteristics is described: (i) a distillation point in the range of 140-300 DEG C; (ii) a cis decalin/trans decalin ratio of above 0.2; (iii) an aromatics content of less than 22 volume %; (iv) a sulphur content of less than 100 ppm; and (v) a net volume calorific value of more than 34.65 Mj/litre.

Description

2194 ~ 47 Jet fuel and method of preparing this jet fuel.
The present invention relates to jet fuels, or fuels for a jet engine, and their method of preparation.
Many processes have been proposed for the manufacture of fuels for jet engines, from a wide range of raw materials.
In general, the fuel for jet engine or jet fuel is produced from a fraction of kerosene directly from atmospheric distillation crude oil and whose distillation points are between 140 and 300 C and, more typically, between 150 and 2700C. This fraction is then either treated in a desulphurisation unit, be processed in a unit of transformation of mercaptans into disulfides.
Another way of production is that consisting of hydrocracking of a fraction of the distillate under vacuum. The fractionation of the effluents makes it possible to obtain jet fuel that does not require other treatments.
However, the jet fuel thus obtained has a power lubricant very weak and insufficient for its use in pure state in jet engines. As a result, he must be mixed with other jet fuels, particularly straight-run fuel fuels, which have a better lubricity and thus compensate for this insufficiency.
The jet fuels are intended to fuel the turbojet burners and aircraft thrusters. In this Indeed, jet fuels must have certain characteristics. In particular, jet fuel Jet A1, which is the most commonly used jet fuel in civil aviation, must imperatively have a content in sulfur content of less than 0.30% by weight, a content of less than 22% by volume, a flash point greater than 38 C, a smoke point greater than 25 mm, and a defrost point below - 47 C. Depending on the route

2 of the prior art, jet fuels have similar energy qualities and a calorific value lower volume, the value of which is less than 34.60 MJ / liter. Other characteristics of jet fuel Jet Al are given in Table 6 appearing in the following this description, after examples of of the invention, this Table 6 also gathering characteristics of the jet fuels produced in these examples.
The demand for jet fuel is growing and means of production of jet fuel are limited within a conventional refinery. The hydrocracking units are extremely expensive and the quantities of jet fuels from the atmospheric distillation of crude oil are limited and depend on the quality of the crude oils.
In addition, refineries whose conversion mode is formed by catalytic cracking, only have jet fuel from direct distillation.
Indeed, the catalytic cracking effluents contain very large quantities of aromatics, olefins, and sulfur products.
Since the dearomatization catalysts, which are platinum-based, are very sensitive to sulfur, is necessary to eliminate sulfur products by a prior hydrotreatment.
However, this hydrotreatment operation is rendered very difficult because of its exothermicity.
In trying to solve this problem encountered in art earlier, the Applicant discovered that it was possible to produce jet fuel from a cut from the catalytic cracking.
The Applicant has furthermore discovered that, so surprisingly, jet fuel produced by cracking catalytic (i.e. high temperature cracking, in the presence of a catalyst and without hydrogen) then hydrotreatment, was different from that obtained by cracking in the presence of hydrogen (hydrocracking) and

3 superior quality to the latter.
Thus, the Applicant has developed a jet fuel characterized in that it possesses:
(i) a distillation point within the range of 140 to 300 C;
ii) a cis decalin / trans decalin ratio greater than 0.2;
(iii) an aromatic content of less than 22% by volume;
(iv) a sulfur content of less than 100 ppm; and v) a lower calorific value by volume which is greater than 34.65 MJ / L, and characterized in that its volume ratio naphthenes is included between 1.2 and 2. paraffins Preferably, the jet fuel according to the invention has a lower calorific value between 34,65 and 35.30 MJ / liter.
The jet fuel according to the invention is therefore different from the jet fuels of the prior art, particular with regard to its calorific value more high, so that it allows a volume consumption lower than that of the jet fuels of the prior art.
The invention also aims to provide a new method for the manufacture of this jet fuel with properties improved. This process is new and original in that that it does not use the conventional ways of producing jet fuel. It allows additional production of jet fuel in a refinery, adding to the to that produced by the atmospheric distillation cup crude oil.
This process makes it possible to obtain a jet fuel from of a cut from the fractionation of the effluent of a catalytic cracked unit. Thus, valuation in jet fuel from a catalytic cracking point cut distillation between 140 and 300 C is possible.
Nevertheless, this cut resulting from a cracking unit catalytic generally requires a number of specific treatments before becoming a jet fuel having the characteristics required for its approval.
Different treatments of the cracker cut

4 catalytic can be considered to obtain the jet fuel. However, according to the invention, the catalytic cracking section is preferably treated in two stages: a hydrotreatment step and a step of dearomatization.
Usually, this catalytic cracking cut has an olefin content between 20 and 45% and a aromatic content of between 40 and 70% by compared to the total volume.
However, jet fuel specifications limit this aromatic content up to 22%, which requires a dearomatization. Moreover, since the catalyst deraromatisation is particularly sensitive to pollutants, it is necessary to operate a hydrotreatment prior to the dearomatization.
The purpose of the hydrotreatment step is to desulphurize, de-nitrogenize and hydrogenate the olefins from the cracked cut Catalytic. If the denaturing of the load caused during of the hydrotreatment step is weak or insufficient, a complementary step of denaturing will be incorporated into diagram of the process.
The cut resulting from catalytic cracking has properties very different from those that allow obtaining the jet fuels of the prior art.
Thus, it contains more olefins than the cut resulting from direct atmospheric distillation, and differs furthermore of the cut in charge of hydrocracking which is a vacuum distillate at higher boiling point.
This explains that the jet fuel of the invention presents characteristics that stand out from those of jet fuel obtained by the usual routes.
The jet fuel according to the invention thus has improved combustion properties in reaction. Indeed, it has a high concentration in polycyclic naphthenes versus concentration naphthenes from jet fuel, which translates into a substantial increase in volumetric energy and greater than

5 0.5%. Therefore, under identical conditions, the consumed volume of the jet fuel according to the invention will be lower than that of a jet fuel of the prior art.
The jet fuel according to the invention generally has a cis decalin / trans decalin ratio greater than 0.2, and preferably greater than 0.3.
This is because the cracking cut catalytic system from which the jet fuel is derived, is rich in olefins, and in particular dicycloolefins, which are precursors of cis decalin. =
The jet fuel according to the invention also has preferably a naphthalene / trans decalin ratio lower than 0.05. Indeed, the hydrogenation step according to the method according to the invention, transforms the vast majority of naphthalenes present in decalines.
The jet fuel according to the invention has naphthenes preferably a ratio between 1.2 and 2.
paraffins In addition, the jet fuel according to the invention has cold-holding properties of very good quality and above that required for Jet Al jet fuel.
As a result, the jet fuel according to the invention can be advantageously used under severe conditions of cold, particularly in the field of military aviation.
In addition, the jet fuel of the invention is to other jet fuel bases, allowing the where appropriate, to improve the properties of carburets, in particular their energy qualities, while respecting the standards required for Jet Al jet fuel.
The process for preparing the jet fuel according to the invention will now be explained.
The step of hydrotreating the cracking cut catalytic is carried out in the presence of a catalyst disposed in the form of one or more fixed beds in a reactor. The catalyst consists of at least one metal hydrogenating and / or hydrogenolysing deposited on a support

6 substantially neutral, for example catalysts based on nickel and molybdenum such as the catalyst TK 525 of the Haldor Topsoe company or the company's HR 348 catalyst Procatalyse.
Other types of catalysts can be used, especially catalysts based on cobalt and molybdenum HR 306 and HR 316 from Procatalyse, KF 752 from company Akzo, and TK 524 and TK 554 from Haldor Topsoe. The reaction temperature is generally understood between 250 and 350 C, under a minimum pressure of 30.105 Pascals (30 bars), with an hourly space velocity from about 1 to 5 h -1, the volume ratio hydrogen /
hydrocarbons at the reactor inlet being between 100 and 500 Nm3 / m3 and preferably between 200 to 300 Nm3 / m3, Advantageously, the temperature is about 280.degree.
a pressure of 35.105 pascals.
The hydrotreatment stage generates reactions strongly exothermic. In order to control this phenomenon, those skilled in the art will adjust various factors, including temperature at the reactor inlet, the ratio hydrogen /
hydrocarbons, and the amount of olefins in the feedstock. A
diluent such as a reactor recycle or, preferentially, kerosene obtained from distillation atmospheric crude oil can be optionally ~
mixed with the filler to reduce its concentration in olefins.
In the case of a reactor where the catalyst is disposed in several fixed beds, a quenching fluid can be injected between these beds, its nature, its flow and its temperature being selected to control the exothermicity of the reactions of this hydro-treatment. A recycle of the unit, hydrogen or, preferably, kerosene of atmospheric distillation, can constitute the quenching fluid.
Partial decaromatization reaction of the effluent from the desulphurisation unit is carried out in the presence a catalyst arranged for example in the form of one or 21g4547

7 several fixed beds in a reactor. The catalyst used is selected according to the operating conditions of the reactor.
The catalyst may be a thioresistant catalyst, constituted by at least one hydrogenating noble metal deposited on a substantially acidic support, this noble metal being in particular platinum or palladium. As examples, thio-resistant catalysts such as catalysts LD 402 from Procatalyse, AS-100 from Criterion and TK
908 from Haldor Topsoe can be used for this purpose.
The catalyst used can also be a catalyst nickel-based, which proves to be an interesting way, because it's cheaper than using catalysts containing platinum or palladium. As examples, catalysts such as catalysts HTC 400 and HTC 500 from Crosfield and C46-7-03 and L3427 from Süd-Chemie can be used. Preferably, the Crosfield HTC 400 catalyst is used.
In the case of a catalyst containing a noble metal, the reaction temperature is generally between 200 and 300 C, under a minimum pressure of 30.105 Pa, with a hourly volume velocity from 1 to 5 h-1, the volume ratio hydrogen / hydrocarbons at the reactor inlet being included between 500 and 900 Nm3 / m3, preferably 600 Nm3 / m3 (NM3 here means Normal m3. 1 Normal m3 corresponds to lm3 of gas under standard conditions of temperature and pressure, that is 0 C and 1 atmosphere - 1.01325.105 Pa).
Advantageously, the temperature is approximately 240 ° C., a pressure of substantially 50.105 Pa.
In the case of a nickel-based catalyst, the reaction temperature is usually between 100 and 200 C, under a minimum pressure of 30.105 Pa, with a hourly volume velocity from 1 to 5 h-1, the volume ratio hydrogen / hydrocarbons at the reactor inlet being included between 600 and 1000 Nm3 / m3, preferably equal to 800 Nm3 / m3.
Advantageously, the temperature is about 160.degree.
a pressure of substantially 50.105 Pa.

- ~ 1 ~ 4547

8 Preferably, the catalyst of the step of deraromatisation is arranged in several beds, between which is injected a quench fluid to control the exothermicity of the dearomatization reaction.
Depending on the types of catalysts used for both steps described above, a complementary step of denunciation may be effected before that of dearomatization. Indeed, some catalysts of decaromatization are sensitive to nitrogen, resulting in their deactivation. Therefore, if the catalyst selected hydrotreater did not sufficiently reduce the nitrogen content of the load, it must be treated in order to have a very low nitrogen content of the order of 10 ppm. This treatment can be done by different means such as a conventional nitrogen trap containing a mass déazotante.
Depending on the type of catalyst used in the decaromatization, a washing of the effluent from the stage hydrotreatment is necessary to remove ammonia and dissolved hydrogen sulphide which are factors limiting or poisoning for certain types of dearomatization catalysts.
The examples below illustrate different modes of preparation of jet fuels according to the prior art and according to the invention. They are not restrictive and are intended to illustrate the advantages of jet fuels according to the invention.
In these examples, reference is made to the single figure of appended drawing, which shows various curves of distillation of jet fuels described in the examples.
Example 1 A charge at distillation points between 150 and 250 C, coming directly from the splitting of a catalytic cracking unit, was treated in accordance with the process according to the invention.
At first, the load was treated in a hydrotreatment unit. A catalyst based 2194,547

9 of alumina having a specific surface area of 220 m 2 / g, a porous volume of 0.5 cm3 / g, containing, in% by weight, 4.2%
nickel oxide and 16.5% molybdenum. We operate at a average temperature of 325 C under about 35.105 Pa, with an hourly volume velocity of 3 h-1 and a ratio hydrogen / hydrocarbons of 200 Nm3 / m3.
For the decaromatisation step, the TK 908 catalyst from Haldor Topsoe. 0 n operates at a average temperature of 240 C under approximately 50.105 Pa, with a hourly volume velocity of 1 h-1 and one. report hydrogen / hydrocarbons of 600 Nm3 / m3.
The characteristics of the load, the effluent after hydrotreatment and the jet fuel obtained after decommissioning.
are summarized in Table 1 below:
Table 1 Jet Fuel Effluent Charge hydrotreating Density at 15 C 0.841 0.827 0.803 Sulfur (ppm) 3000 19 0 Nitrogen (ppm) 100 5 0 compounds aromatic (% by volume) 45.4 44 7.2 olefins (% by volume) 40.3 0 0 naphthenes paraffins - 0.54 1.54 cis decalin trans decalin - - 0,55 naphthalene trans decalin - - 0 2_ ~ 94547 The distillation curve is shown in the figure single annexed.
Example 2 A mass mixture composed of 50% of a fraction 5 kerosene distillation points between 140 and 270 C from the direct distillation of crude oil, and 50% of a distillation point charge of 160 and 240 C, directly from the splitting of a unit of catalytic cracking, has been treated in accordance with the

Process according to the invention.
At first, the load was treated in a hydrotreatment unit. An identical catalyst is used to that of Example 1. It operates at an average temperature 300 ° C., at about 35.105 Pa, with a volume velocity 4 h-1 and a hydrogen / hydrocarbons ratio of 200 Nm3 / m3.
For the decaromatisation step, the TK 908 catalyst from Haldor Topsoe. We operate at a average temperature of 270 C, under approximately 50.105 Pa, with an hourly volume velocity of 3 h-1 and a ratio hydrogen / hydrocarbons of 600 Nm3 / m3.
The characteristics of the load, the effluent after hydrotreatment and jet fuel obtained after deraromatisation are summarized in Table 2 below.
after:

11 Table 2 Jet Fuel Effluent Blend hydrotreating Density at 15 C 0.832 0.823 0.813 Sulfur (ppm) 4565 62 0.1 Nitrogen (ppm) 91 5 0 compounds aromatic (% by volume) 38 36.1 21 olefins (% by volume) 13.9 0 0 naphthenes paraffins - 0.35 0.68 cis decalin trans decalin - - 0.48 naphthalene trans decalin - - 0 The distillation curve is reproduced on the figure.
single annexed.
This example illustrates the use of a fraction kerosene from the direct distillation of crude oil as a thinner, which allows both to control the exothermicity of hydrotreatment reactions and to improve the basic qualities of the said fraction kerosene (in particular defrost point and power lower heat).
Example 3 A distillation point charge of between 150 and 270 C, coming directly from the splitting of a unit catalytic cracking, has been treated in accordance with the process according to the invention.
At first, the load was treated in a - ~ 19454 ~

12 hydrotreatment unit. A catalyst based of alumina having a surface area of 210 m 2 / g, a porous volume of 0.6 cm3 / g, and containing 2.8% of cobalt and 13.8% molybdenum oxide. We operate at a average temperature of 325 C, under about 35.105 Pa, with an hourly volume velocity of 3 h-1 and a ratio hydrogen / hydrocarbons of 300 Nm3 / m3.
For the decaromatisation step, the HTC 400 Crosfield catalyst. We operate at a temperature average of 160 C under about 50.105 Pa, with a speed hourly volume of 3 h-1 and a report hydrogen / hydrocarbons of 800 Nm3 / m3, The characteristics of the load, the effluent after hydrotreatment, and jet fuel obtained after deraromatisation are shown in Table 3 below:
Table 3 Jet Fuel Effluent Charge hydrotreating Density at 15 C 0.827 0.819 0.805 Sulfur (ppm) 3600 4.5s 10 Nitrogen (ppm) 91 0 0 compounds aromatic (% by volume) 49 44 21.3 olefins (% by volume) 30.7 0.5 0 naphthenes paraffins - 0,60 1,28 cis decalin trans decalin - - 0,55 naphthalene trans decalin - - 0

13 The distillation curve is shown in the figure single annexed.
Example 4 A distillation point charge of between 140 and 250 C, from the atmospheric distillation of a crude oil, is processed in a softening unit of mercaptans of the "REROX" type, the principle of which is described succinctly page 877 of the book "Refining and engineering P. Wuithier, IFP, Volume 1, 1972 edition.
It operates in a manner known per se, in the presence of catalyst based on cobalt phthalocyanine, at a pressure of 8.105 Pa and at a temperature of 50 C.
The characteristics of the load and the carburettor obtained are summarized in Table 4 below:
Table 4 Carburetor charge Density at 15 C 0.785 0.785 Sulfur (ppm) 450 404 Nitrogen (ppm): 55: 55 Aromatic compounds (% by volume) 17.5 17.5 Olefins (% by volume) 0 0 naphthenes 0.55 0.55 paraffins cis decalin decalin trans - 0.04 naphthalene trans decalin - 8.06 The distillation curve is reproduced in the figure single annexed.
Example 5 A distillation point charge of between 350 and 560 C, from vacuum distillation, is treated

14 in a double reactor hydrocracker of the Unicracking type, developed by UNOCAL and UOP. For reference, this device hydrocracking is briefly described on page 761 of the book "Refining and Chemical Engineering" by P. Wuithier, IFP, Volume 1, 1972 edition.
The vacuum distillate feedstock is pre-treated in a first reactor in the presence of a denitrogenation catalyst.
Then, the effluent obtained is treated in the reactor of cracking. The operating conditions are substantially similar to those shown on page 764 of the book "Refining and chemical engineering "of P. Wuithier, IFP, Volume 1, edition of 1972.
The characteristics of the load and the jet fuel obtained by fractionation are shown in Table 5 hereinafter Table 5 Carburetor charge Density at 15 C 0.928 0.806 Sulfur (ppm) 12100 10 Nitrogen (ppm) 866 0 Aromatic compounds (% by volume) 52.5 9 Olefins (% by volume) 0 0 naphthenes - 1.14 paraffins cis decalin trans decalin - 0.14 naphthalene trans decalin - 0.11 The distillation curve is shown in the single figure attached.
The set of characteristics of Al JET and Examples 1, 2, 3, 4 and 5 are described in US Pat.
* trademark Table 6 below.
The freezing points of Examples 1 and 3 are, in particular, well below the minimum required, ie lower than -47 C, and thus allow 5 potential of these jet fuels under extreme cold. Moreover, we note that the power lower calorific value of the jet fuel obtained according to the invention is particularly high compared to those of the prior art.

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Claims (11)

Claims 1. Jet fuel featuring the combination of following characteristics:

(i) a distillation point within the range of 140 to 300°C;

ii) a cis decalin/trans decalin volume ratio greater than 0.2;

iii) an aromatics content of less than 22% by volume;

iv) a sulfur content of less than 100 ppm; and (v) a lower calorific value by volume which is greater than 34.65 Mj/litre, and characterized in that its naphthenes volume ratio is between 1.2 and 2.
paraffins 2. Jet fuel according to claim 1, characterized in what its lower calorific value by volume is between 34.65 and 35.30 Mj/litre. 3. Jet fuel according to claim 1 or 2, characterized in that its volume ratio cis decalin/trans decalin is greater than 0.3. 4. Jet fuel according to any of the claims 1 to 3, characterized in that its ratio naphthalene/trans volume decline is less than 0.05. 5. Process for the preparation of a jet fuel according to one any one of claims 1 to 4, characterized in that subjecting a catalytic cracking cut distilling between 140 and 300°C in a hydrotreatment step, then at a dearomatization step. 6. Method according to claim 5, characterized in that the hydrotreating step is carried out on at least one bed fixed catalyst containing at least one hydrogenating metal and/or hydrogenolyzer, at an average temperature between between 250 and 350°C, under a minimum pressure of 30.10 5.Pa, with an hourly volume velocity of 1 to 5 h-1 and a ratio hydrogen/hydrocarbons between 100 and 500 Nm3/m3. 7. Method according to claim 6, characterized in that that the catalyst contains cobalt and molybdenum or nickel and molybdenum. 8. Method according to any one of claims 5 to 7, characterized in that the dearomatization step is carried out in the presence of a catalyst containing at least one metal noble including platinum and/or palladium, disposed on at least one fixed bed, at a temperature comprised between 200 and 300°C and at a minimum pressure of 30.10 5.Pa, with an hourly volume velocity of 1 to 5 h-1 and a hydrogen/hydrocarbon ratio between 500 and 900 Nm3/m3. 9. Method according to any one of claims 5 to 7, characterized in that the dearomatization step is carried out in the presence of a nickel-based catalyst disposed on at least one fixed bed, at a temperature between 100 and 200°C and at a minimum pressure of 30.10 5.Pa, with a hourly volume velocity from 1 to 5 h-1 and a ratio hydrogen/hydrocarbons between 600 and 1000 Nm3/m3. 10. Method according to any one of claims 5 to 9, characterized in that a diluent is used in at least one of the steps of said method for controlling exothermicity of the reaction. 11. Method according to claim 10, characterized in that that a diluent is mixed with the catalytic cracking cut before hydrotreating, this diluent being a fraction kerosene from the atmospheric distillation of petroleum raw.