ES2418141T3 - Manufacturing process of hydrocarbon fluids rich in naphthenic hydrocarbons - Google Patents

Abstract

Method of preparing a hydrocarbon fluid containing at least 70% by weight of naphthenic hydrocarbons and having an aromatic hydrocarbon content of less than or equal to 500 ppm by weight, characterized in that it comprises: - (a) at least one extraction stage , of a fractionation column of the effluents of a conversion unit without hydrogen, of a fraction of hydrocarbons whose distillation range is in a range from 100 ° C to 400 ° C and containing at least 70% by volume of unsaturated cyclic hydrocarbons, - (b) at least one hydrodesulphurization stage of said fraction, so that a desulfurized fraction having a sulfur content of less than 50 ppm by weight is obtained, - (c) at least one controlled hydrogenation stage of said desulfurized fraction, in the presence of hydrogen and of a catalyst comprising between 10 and 70% by weight of nickel deposited on a solid support, to a temperature between 80 ° C and 250 ° C and a partial pressure of hydrogen between 50 and 160,105 Pa, the conditions of controlled hydrogenation being chosen such that a hydrocarbon fluid having an aromatic hydrocarbon content of less than or equal to 500 ppm by weight is obtained , - (d) at least one stage of recovery of the hydrocarbon fluid containing at least 70% by weight of naphthenic hydrocarbons and having an aromatic hydrocarbon content of less than or equal to 500 ppm by weight from stage (c).

Description

Manufacturing process of hydrocarbon fluids rich in naphthenic hydrocarbons

The invention relates to a process for preparing a hydrocarbon fluid rich in naphthenic hydrocarbons. More particularly, the invention relates to a process for preparing non-toxic, non-polluting and odorless hydrocarbon solvents.

In the description, the example and the following claims, all distillation ranges mentioned are measured according to ASTM D-86.

STATE OF THE TECHNIQUE

Many organic solvents with petroleum origin are currently known. They are commonly used in cleaning, extraction or dilution applications (for example, for paints or inks).

These types of solvents are obtained by direct distillation of petroleum fractions. Solvents must be able to dissolve organic products. Therefore, they must have a good solvent power with respect to these products.

The aniline point explains the solvent power of a product. It is usually measured, in ° C, by the ISO 2977 method. The lower the aniline point, the better the solvent power of the compound. Now, aromatic hydrocarbons have a low aniline point and are therefore very good solvents. For example, xylene has an aniline point of 12 ° C, toluene has an aniline point of 9 ° C. But aromatic hydrocarbons have the significant disadvantage of being very toxic.

Solvents obtained by distillation of crude oil generally contain a high content of aromatic hydrocarbons, which raises the problem of their high toxicity.

For example, petroleum fractions having a distillation range between 230 ° C and 300 ° C, used as solvents for printing ink, may have aromatic compounds contents of 20 to 30% by weight.

In addition, due to their high boiling point, these heavy aromatic compounds are difficult to dry. In particular, in printed ink, they tend to evaporate very slowly, so that they persist for a long time in the inks, which can give off toxic vapors and unpleasant odors during use.

Depending on the applications of these solvents, sometimes it has even been proposed, in order to further increase its solvent power, to add other aromatic compounds such as benzene, toluene or xylene: since these compounds are particularly dangerous for the body, its content in solvents must therefore be controlled.

The need to manufacture solvents less harmful to health implies reducing their content in aromatic compounds. Therefore, they must be replaced by other less toxic compounds.

In order to limit the content of benzene compounds in solvents, it has been proposed to incorporate non-toxic paraffins into the latter. But in this case, other problems arise, such as the decrease of the solvent power or the solidification of the products at low temperature (5-7 ° C).

The substitution of aromatic compounds in solvents means that they are replaced by other compounds, not only less toxic, but also retain a low aniline point, in order to maintain a good solvent power. Naphthenic hydrocarbons have appeared as a good alternative to aromatic compounds, due to their good solvent power and low toxicity.

In order to solve the toxicity and contamination problems induced by the manufacture of the solvents described above, and without significant loss of solvent power, US Patent No. 3 996 304 discloses a manufacturing process for hydrocarbon solvents Non-polluting and non-toxic Thus, it is a question of obtaining cycloparaffinic hydrocarbons by catalytic hydrogenation of aromatic hydrocarbons.

More particularly, this process consists in selecting oil fractions rich in certain aromatic compounds such as benzene, toluene, xylene or even naphthalene, in subjecting them to distillation to obtain concentrates of these different pure aromatic products, and finally in hydrogenating these aromatic concentrates to obtain the corresponding cycloparaffins.

For example, this patent describes a manufacturing process of cyclohexane comprising the steps of:

(to)

 distillation of a fraction of benzene-rich oil, to obtain a major fraction containing benzene,

(b)

 solvent extraction of the main fraction containing benzene, to separate benzene from the paraffinic and naphthenic compounds contained in said main fraction,

(C)

 solvent recovery enriched in benzene,

(d)

 separation of the solvent, on the one hand, and benzene, on the other hand, by distillation,

(and)

 benzene recovery with a purity of at least 99%,

(F)

 hydrogenation of benzene on a non-acid catalyst containing platinum and / or palladium, tin, rhodium and an alkali metal.

This procedure, which implements numerous stages, has the disadvantage of being complicated and expensive. It needs significant investments in refineries, in which specific equipment for manufacturing, extraction of intermediate aromatic concentrate and hydrogenation must be provided.

Therefore, it follows that the prior art only proposes unsatisfactory procedures with respect to the limitations that currently exist, both in terms of health and the environment and in economic terms for refineries. None of the existing procedures make it possible to produce non-toxic and non-polluting hydrocarbon solvents easily and economically.

It is known to valorise hydrocarbon charges by converting them into hydrocarbon products rich in naphthenic hydrocarbons and having a low content of aromatic compounds.

Thus, US Pat. No. 4,875,992 discloses in a general manner a method that allows a hydrocarbon-rich filler to be converted into polycyclic aromatic compounds with condensed cycles into high density fuel for jet aircraft. This process comprises a desulfurization / denitrogenation stage by hydrotreatment, which is followed by a hydrogenation stage that results in the partial saturation of the aromatic compounds of the initial charge.

Also, US Patent 6,210,561 generally describes a process in which a hydrocarbon filler having a boiling range greater than 100 ° C is converted into a product rich in naphthenic hydrocarbons with a low content of aromatic compounds, with a view to later use, produced during steam cracking. This procedure essentially comprises four stages of treatment, which are:

-

 a) a hydrotreatment stage to remove sulfur and nitrogen compounds,

-

 b) a stage of saturation of the double bonds by controlled hydrogenation,

-

 c) a steam cracking stage of the desulfurized, denitrogenated and hydrogenated product, after which a product consisting of hydrogen, C1-4 hydrocarbons, naphtha, steam cracking diesel and steam cracking tar is obtained, Y

-

 d) a stage of fractionation and recovery of the different products.

DESCRIPTION OF THE INVENTION

The present invention aims precisely to solve the drawbacks of prior art procedures. These drawbacks are, on the one hand, the toxicity and contaminating nature of organic solvents from oil refining and used so far and, on the other hand, the complexity and the need for significant investments required by the implementation of procedures for manufacture of non-polluting solvents.

Specifically, the invention aims to propose a process that allows, in a simple and economical way, to prepare non-polluting solvents based on naphthenic hydrocarbons. Naphthenic hydrocarbons (or naphthenes) means hydrocarbon molecules that comprise at least one saturated cycle, also called paraffin cycles.

For this purpose, the object of the invention is a preparation process according to claim 1.

The process according to the invention has a first advantage: to be simpler and more efficient than the known processes for the preparation of solvents rich in naphthenic hydrocarbons. Indeed, it does not need specific investments in refineries and does not require the intervention of additional solvents that can be expensive products. With respect to the prior art procedures, the process of the invention allows to reduce the manufacturing costs of naphthene-rich solvents.

The process according to the invention has a second very important advantage: that of allowing the valuation of refinery fractions increasingly difficult to valorise. These are the gasoline and diesel fractions from catalytic cracking, rich in aromatic hydrocarbons, and which are difficult to integrate into fuel combinations, due to the increasingly stringent specifications regarding the permitted contents of aromatic compounds.

This procedure therefore has a double advantage: on the one hand it uses a fraction that is difficult to value due to its content in aromatic compounds, and on the other hand it leads to a product with a high added value, non-toxic and environmentally friendly.

In a manner known in itself, the petroleum and petrochemical industries have resorted to heavy hydrocarbon conversion procedures, in which high molecular weight and high boiling hydrocarbon molecules are cleaved to give smaller molecules, which can Boil in lower temperature ranges, convenient for the intended use.

Among them, certain conversion procedures without hydrogen input are put into practice. Conversion procedures without hydrogen input are specifically understood, but not limited to, cracking procedures, whether thermal or catalytic, viscorrection procedures or even steam cracking.

In particular, the oil industry has procedures called cracking in a fluid state. In this type of process, the hydrocarbon charge, generally sprayed in the form of fine droplets, is brought into contact with high temperature heat transfer particles circulating in the reactor in the form of a fluidized bed, that is, in more or less dense suspension in the inside of a gaseous fluid that guarantees or helps its transport. Upon contact with the hot particles, evaporation of the charge occurs, followed by cracking of the hydrocarbon molecules. The cracking reaction is of the thermal type when the particles have only a heat transfer function. It is of the catalytic type when the particles also have a catalytic function, that is, they have active sites that favor the cracking reaction. This is the case in the catalytic cracking process in the fluid state (called the FCC procedure, of the English "Fluid Catalytic Cracking").

Steam cracking, used in petrochemicals, is a hydrocarbon conversion process that is implemented without hydrogen input and without a catalyst, but in the presence of water vapor and at a high temperature (approximately 800 ° C). In particular, it allows, from light hydrocarbons, called naphtha, to produce ethylene and propylene.

The first stage of the process according to the invention consists in extracting, from a fractionation column of the effluents of a conversion unit without hydrogen supply, a fraction of hydrocarbons, whose distillation range is in the range of 100 ° C to 400 ° C .

Preferably, the hydrocarbon fraction extracted during this first stage comes from a catalytic cracking unit, or even comes from a steam cracking unit.

Also preferably, the hydrocarbon fraction extracted during this first stage has a distillation range in the range of 135 ° C to 330 ° C.

More preferably, the hydrocarbon fraction extracted during this first stage has a distillation range in the range of 145 ° C to 260 ° C.

The hydrocarbon fraction from the catalytic cracking selected for the first stage of the process of the invention is rich in unsaturated cyclic compounds. It contains at least 70% by volume unsaturated cyclic compounds.

Specifically, the unsaturated cyclic compounds present in this fraction may be aromatic compounds, thiophene or benzothiophene compounds, unsaturated cyclic nitrogen compounds, unsaturated cyclic sulfur compounds, cyclo olefins.

Preferably, the unsaturated cyclic compounds are aromatic compounds or cyclo-olefins.

The second stage of the process according to the invention consists in subjecting the hydrocarbon fraction extracted from the catalytic cracking unit to hydrodesulfurization in the presence of a catalyst and in the presence of hydrogen.

This stage is intended to desulfurize at least in part the hydrocarbon fraction from the catalytic cracking, so that the compounds that could constitute poisons for the hydrogenation catalyst used during the third stage of the process are eliminated.

The hydrodesulfurization catalyst used is constituted by a solid support and by an active phase.

The active phase contains at least one metal of the periodic classification of the elements.

Preferably, the metal can be chosen from group VI metals, group VIII metals or mixtures thereof, on a support based on one or more refractory oxides, preferably alumina, silica and / or mixtures thereof.

These hydrodesulfurization catalysts well known to those skilled in the art can be used during this stage but after sulfurization. For example, cobalt-molybdenum (CoMo), nickel-molybdenum (NiMo) or even nickel-tungsten catalysts can be used, which are sulphided in situ or ex situ.

Another catalyst particularly effective for performing the hydrodesulphurization step according to the process of the invention is constituted, on the one hand, by a solid support comprising a silica-alumina dispersed in an alumina binder and, on the other hand, by an active phase which it comprises a combination of platinum and palladium containing at least 0.1% by weight of each of them and, preferably, from 0.25 to 1% by weight.

Preferably, the solid support contains between 15% and 30% by weight of alumina binder with respect to the total weight of the silica-alumina and alumina binder, and the silica-alumina contains between 15% and 30% by weight of alumina.

The hydrodesulfurization stage is carried out under conditions that allow obtaining a fraction of desulfurized hydrocarbons having a sulfur content of less than or equal to 50 ppm by weight.

Preferably, the hydrodesulfurization is carried out under conditions that allow obtaining a fraction of desulfurized hydrocarbons having a sulfur content of less than or equal to 10 ppm by weight and, even more preferably, less than or equal to 2 ppm by weight.

The third stage of the process of the invention consists in subjecting the desulfurized hydrocarbon fraction to controlled hydrogenation in the presence of a catalyst and hydrogen.

This stage aims to transform at least in part the unsaturated cyclic hydrocarbons present in large quantities in the desulfurized fraction into naphthenic compounds.

The hydrogenation catalyst used is constituted by a solid support and by an active phase.

The solid support can be any refractory mineral oxide and is advantageously chosen from the silicas, aluminas and silica-aluminas.

Preferably, the solid support is a deactivated alumina.

The hydrogenating metal is nickel. The content of the hydrogenation catalyst in nickel is between 10% and 70% by weight.

It is preferably between 20% and 30% by weight in the highly dispersed phase (catalyst obtained by impregnation) and between 40% and 65% by weight in the classical phase (catalyst obtained by extrusion). The controlled hydrogenation step takes place at a temperature between 80 ° C and 250 ° C, preferably between 100 ° C and 240 ° C.

The ratio H2 / HC (hydrogen with respect to hydrocarbons) is between 100 and 1000 included.

The partial pressure of hydrogen is between 50 and 160,105 Pa.

The hydrogenation conditions are controlled so that the unsaturated cyclic hydrocarbons are selectively hydrogenated to give naphthenes.

Preferably, the hydrogenation conditions are controlled so that the aromatic hydrocarbons are selectively hydrogenated to give naphthenes.

According to another characteristic of the process of the invention, the controlled hydrogenation stage is followed by a fractionation stage by distillation of the hydrogenated fraction, to obtain several fractions having narrower distillation intervals.

Thus, according to a preferred mode of the invention, hydrocarbon fractions from the controlled hydrogenation stage can be specifically selected such as a light fraction whose distillation range is in the range of 100-205 ° C, an intermediate fraction whose distillation range is in the range of 170-270 ° C and a heavy fraction whose distillation range is in the range of 200400 ° C.

Even more preferably, the fractionation step may consist of selecting fractions having distillation intervals whose amplitude is less than or equal to 55 ° C, preferably less than or equal to 30 ° C.

The choice of finer hydrocarbon fractions allows to obtain final products that have specific properties, which can find various applications and be valued in different fields.

Products from the light fraction, whose distillation range is in the range of 100205 ° C, can be specifically valued as solvents, for example for paints and varnishes. You can also find applications for degreasing metals.

Products from the intermediate fraction, whose distillation range is in the range of 170-270 ° C, can find applications specifically as paint and varnish solvents, as degreasing agents for metals or even as aluminum rolling agents.

Finally, products from the heavy fraction whose distillation range is in the range of 200-400 ° C can be used specifically as solvents for printing ink or as substituents of silicone oils in silicone putties.

The applications of the products obtained by the process of the invention are not limited to the uses mentioned above.

DETAILED DESCRIPTION OF THE INVENTION

The invention will be better understood with the aid of the attached figure 1, which schematically represents a naphthenic solvent manufacturing device according to the process of the invention.

In a first stage, the hydrocarbon filler containing at least 70% by volume of unsaturated cyclic compounds is extracted, through the conduit 5, of a column 1 of fractionation of the effluents of a catalytic cracking unit not shown in the figure.

The filler rich in unsaturated cyclic compounds is injected through conduit 5 into a hydrodesulphurisation unit 2, in which it undergoes a desulfurization in the presence of a desulphurization catalyst and hydrogen, to produce an at least partially desulphurized fraction, extracted through the conduit. 6.

The desulfurized fraction is injected through conduit 6 into a controlled hydrogenation unit 3, in which it undergoes controlled hydrogenation in the presence of a hydrogenation and hydrogen catalyst, to produce a hydrocarbon fraction containing at least 70% by weight. of naphthenes, removed through the duct

7.

This naphthene-rich hydrocarbon fraction can then be sent through the conduit 7 to a separation column 4 to be divided into several fractions having narrower distillation intervals. A light fraction can be extracted through the conduit 8, an intermediate fraction through the conduit 9 and a heavy fraction through the conduit 10, to be subsequently evaluated in different applications.

Example

The following example is intended only to illustrate the invention, and not limit the scope.

A hydrocarbon fraction from catalytic cracking is treated according to the process of the invention, the characteristics of which are shown in Tables 1 and 2 below.

TABLE 1: Distillation according to ASTM D86 of the fraction to be treated.

Hydrocarbon fraction from catalytic cracking

Distilled% (volume)

Temperature (ºC)

Starting point

142

5

154

10

158

fifty

177

70

185

90

203

95

219

Final point

2. 3. 4

TABLE 2: Characteristics of the fraction to be treated.

Hydrocarbon fraction from catalytic cracking

features

Values

Density at 15ºC

0.8417

Naphthene content (% by weight)

8.0

Content in aromatic compounds (% by weight)

75.3

Cyclo-olefins content (% by weight)

3.2

Bromine Index (mg of Br / 100 g)

3499

Sulfur compounds content (% by weight)

0.076

Aniline Point (ºC)

2. 3

The operating conditions of the different stages of the treatment are shown in table 3. TABLE 3: Operating conditions

HYDRODESULFURATION

Catalyst

How to alumina

H2 partial pressure (105 Pa)

58.6

Temperature (ºC)

315

CONTROLLED HYDROGENATION

Catalyst

Ni on alumina

H2 partial pressure (105 Pa)

51

Temperature (ºC)

130

Reason H2 / HC (N, liter / liter)

300

In the case of this example, the treated fraction has not been fractionated in a distillation column after the controlled hydrogenation step. The characteristics of the hydrocarbon fluid obtained are indicated in Table 4. TABLE 4: Characteristics of the hydrocarbon fluid obtained.

features

Values

Density at 15ºC

0.7856

Naphthene content (% by weight)

86.5

Content in aromatic compounds (ppm by weight)

100

Bromine Index (mg of Br / 100 g)

36

Sulfur compounds content (ppm by weight)

0.4

Aniline Point (ºC)

56.4

20 In Tables 2 and 4: -The aniline point is measured by the ISO 2977 method,

25 - The bromine index is measured by the ASTM D2710 method. This method determines the rate of bromine reactive compounds present in a hydrocarbon fraction. It allows therefore to determine the rate of unsaturated compounds present in the fraction.

The richer the hydrocarbon fraction in unsaturated compounds, the higher the bromine index. The results of table 4 above show that the process of the invention has allowed manufacturing, from a very aromatic fraction (75.3% by weight), a hydrocarbon product suitable for recovery as Non-toxic and non-polluting solvent.

5 In fact, the final product obtained already contains only 100 ppm by weight of aromatic compounds and less than 1 ppm by weight of sulfur compounds. It is devoid of the toxic compounds present in the initial fraction.

10 A large part of the unsaturated compounds present in the initial fraction have disappeared, in particular aromatic compounds, transformed into naphthenic compounds.

This high content of naphthenic compounds, however, allows it to have a good solvent power and therefore be valued as such. fifteen

Claims (14)

1. Method of preparing a hydrocarbon fluid containing at least 70% by weight of naphthenic hydrocarbons and having an aromatic hydrocarbon content of less than or equal to 500 ppm by weight, characterized in that it comprises:

-

 (a) at least one extraction stage, of a fractionation column of the effluents of a conversion unit without hydrogen input, of a fraction of hydrocarbons whose distillation range is in a range from 100 ° C to 400 ° C and that contains at least 70% by volume unsaturated cyclic hydrocarbons,

-

 (b) at least one hydrodesulphurization step of said fraction, so that a desulfurized fraction having a sulfur content of less than 50 ppm by weight is obtained,

-

 (c) at least one stage of controlled hydrogenation of said desulfurized fraction, in the presence of hydrogen and of a catalyst comprising between 10 and 70% by weight of nickel deposited on a solid support, at a temperature between 80 ° C and 250 ° C and a partial pressure of hydrogen between 50 and 160,105 Pa, the conditions of controlled hydrogenation being chosen such that a hydrocarbon fluid having an aromatic hydrocarbon content of less than or equal to 500 ppm by weight is obtained,

-

 (d) at least one stage of recovery of the hydrocarbon fluid containing at least 70% by weight of naphthenic hydrocarbons and having an aromatic hydrocarbon content of less than or equal to 500 ppm by weight from stage (c).

2.

Method according to claim 1, characterized in that the conversion unit without hydrogen input is a catalytic cracking unit.

3.

Method according to claim 1, characterized in that the conversion unit without hydrogen supply is a steam cracking installation.

Four.

Process according to any one of claims 1 to 3, characterized in that the hydrocarbon fraction extracted during step (a) has a distillation range in the range of 135 ° C to 330 ° C.

5.

Process according to any one of claims 1 to 3, characterized in that the hydrocarbon fraction extracted during step (a) has a distillation range in the range of 145 ° C to 260 ° C.

6.

Process according to any one of claims 1 to 5, characterized in that the unsaturated cyclic hydrocarbons present in the hydrocarbon fraction extracted during step (a) belong to the group consisting of aromatic compounds, thiophene compounds, benzothiophene compounds, sulfur compounds unsaturated cyclics, unsaturated cyclic nitrogen compounds, cyclo olefins, and mixtures thereof.

7.

Process according to any one of claims 1 to 6, characterized in that the unsaturated cyclic hydrocarbons present in the hydrocarbon fraction extracted in step (a) are aromatic compounds and / or cyclo-olefins.

8.

Process according to one of claims 1 to 7, characterized in that the hydrodesulphurization step to which the hydrocarbon fraction is subjected leads to a desulfurized fraction having a sulfur content of less than or equal to 10 ppm by weight.

9.

Process according to one of claims 1 to 7, characterized in that the hydrodesulphurization step to which the hydrocarbon fraction is subjected leads to a desulfurized fraction having a sulfur content of less than or equal to 2 ppm by weight.

10.

Process according to any one of claims 1 to 9, characterized in that the hydrodesulfurization catalyst comprises at least one metal selected from group VI metals, group VIII metals or mixtures thereof, on a support based on one or more refractory oxides , preferably alumina, silica and / or mixtures thereof.

eleven.

Process according to any one of claims 1 to 10, characterized in that the hydrodesulfurization catalyst comprises:

-

an active phase comprising a combination of platinum and palladium containing at least 0.1% by weight of each of them and, preferably, 0.25 to 1% by weight, and

-

a solid support comprising a silica-alumina, dispersed in an alumina binder, said support containing between 15% and 30% by weight of alumina binder with respect to the total weight of the silica-alumina and alumina binder, and said silica-alumina containing between 15% and 30% by weight of alumina.

12.

Process according to one of claims 1 to 11, characterized in that the controlled hydrogenation is followed by a fractionation step by distillation of the hydrogenated fraction so that at least a narrow fraction having a distillation range whose amplitude is less than or equal is obtained at 55 ° C.

13.

Method according to claim 12, characterized in that the fractionation step is performed so that at least a narrow fraction is obtained having a distillation range whose amplitude is less than or equal to 30 ° C.

14.

Method according to any one of claims 1 to 13, characterized in that the fractionation stage of the hydrocarbon fluid recovered in step (d) allows to select: - a light fraction whose distillation range is in the range of 100-205 ° C;

-

an intermediate fraction whose distillation range is in the range of 170-270; -a heavy fraction whose distillation range is in the range of 200-400 ° C.