Improved method for selective reduction of benzene and light unsaturated compounds content in different hydrocarbon fractions

FIELD: oil and gas industry.

SUBSTANCE: first raw stock comprises mainly hydrocarbons containing at least 4 hydrocarbon atoms and includes at least one unsaturated compound, including benzene, with the property that the above first raw stock is treated in a distillation zone, a zone of impoverishment and a zone of rectification united with a zone of hydrogenation reaction, at least partial, in regard to the zone of distillation, containing at least one catalytic layer. Hydrogenation of at least a part of unsaturated compounds comprising the first raw stock is carried out in the presence of a hydrogenation catalyst and a gas flow containing hydrogen. The first raw stock is extracted from the reaction area, at least at a level of extraction in the distillation zone. The reaction zone effluent, at least partially, is again introduced to the distillation zone, at least at the level of repeated introduction in order to ensure continuity of distillation and to receive the effluent impoverished by the unsaturated compounds in the upper part of the distillation zone, a lateral branch to the distillation zone and in the lower part of the distillation zone. The method includes treatment of at least one second raw stock comprising at least one unsaturated compound, including benzene, at least partially injected to the zone of hydrogenation reaction being external in regard to the distillation zone. At that in the second raw stock benzene content varies from 2 vol.% up to 10 vol. %.

EFFECT: reducing the content of light unsaturated compounds, especially benzene, in all fractions.

23 cl, 3 dwg, 1 tbl

The present invention relates to a method of reducing the content of unsaturated compounds in hydrocarbon fractions, more selective way of reducing the content of unsaturated compounds, particularly benzene, in at least one hydrocarbon fraction.

Taking into account the acknowledged hazards of benzene and, to a lesser extent, olefins, unsaturated compounds and aromatic compounds that are heavier than benzene, the General trend is to reduce the content of these components in gasoline.

Benzene is carcinogenic and, therefore, requires the maximum extent possible to limit any possibility of contamination of the ambient air, in particular, will nearly eliminate it from automobile fuels. In the United States newly created fuel should not contain more than 0,62% benzene; in Europe, even if the requirements are not as stringent argue for a gradual tendency to this value.

Olefins were recognized as among the most reactive hydrocarbons as in the cycle of photochemical reactions with oxides of nitrogen, which is carried out in the atmosphere and which leads to the formation of ozone. The increase in the concentration of ozone in the air can be a source of respiratory disorders. The reduction in the content of olefins in gasoline, in particular the most light Olaf the new, which have the greatest tendency to evaporate during the manipulation of the fuel is, therefore, desirable.

Aromatic compounds that are heavier than benzene, also possess, but to a lesser extent, carcinogenic, and their content in gasoline pools are seen gradually decreasing.

The content of benzene in gasoline is highly dependent on the content of different fractions of its components. These different fractions are, in particular:

- reforming product resulting from the catalytic purification of oil intended for the preparation of aromatic hydrocarbons containing mainly from 4 to 12 carbon atoms in their molecule, a very high octane number which gives the gasoline antiknock properties; these fractions obtained by catalytic reforming, were only cleared up to the present time in order to reach the requirements for benzene in gasoline pools 1% of the volume. In order to comply with the requirement, for example, to 0.62% of the volume, it is necessary that the other factions would be purified, in particular faction, described in detail below.

- fraction C₅/C₆such as:

light oil direct distillation (Light Straight Run),

the oil obtained by hydrocracking unit

- other fractions enriched in benzene and the more serious the integer aromatic compounds by distillation and hydrobromide and leaving the catalytic cracking unit or fluid catalytic cracking FCC (Fluid Catalytic Cracking according to English terminology), and light gasoline from the unit coking unit (coker according to English terminology), delayed coking unit, installation, fluid catalytic cracking, or installation of coking type Flexicoker, or install a light cracking (visbreaking according to English terminology),

- fractions enriched in benzene and heavier aromatic compounds, obtained after separation and hydrobromide gasoline resulting from the cracking of olefins (cracking of olefins With₄-C₁₀to ethylene and propylene in the acidic catalyst)

- fractions enriched in benzene and heavier aromatic compounds from plant production of olefins, the type of cracking in the vapor phase (Pyrolysis gasoline according to English terminology), or coke ovens (Coke Oven Light Oil according to English terminology) after distillation and hydrobromide.

For reasons of harm described above, it is necessary, therefore, to reduce the content of benzene and heavier aromatics in these different fractions. Can be addressed several ways.

The first way is to restrict oil, which is the feedstock for catalytic reforming unit, the content of the precursors of benzene, such as cyclohexane and Methylcyclopentane. This decision effectively sensitive mind is nishit benzene content in effluent of reformer, but still can't cope with this one, when it is necessary to descend to such low concentrations as to 0.62%.

The second way is to remove the distilled light fraction from the product of the reforming containing benzene. This solution leads to a loss of 15-20% of hydrocarbons, which could be assessed in gasoline.

The third way is to extract benzene present in effluent of the reforming unit. In principle, applicable to several well-known methods: solvent extraction, extractive distillation, adsorption. These technologies are expensive and require the ability to apply the extracted benzene fraction.

The fourth way is the chemical conversion of benzene to convert it into a component, which is not aimed legitimate restrictions. Alkylation with ethylene, for example, turns benzene, mainly in ethylbenzene. However, this operation is expensive because of the intervention of adverse reactions that make the inevitable separation processes with large energy consumption.

The benzene product of reforming, similarly, can be gidrirovanny in cyclohexane. Given that it is impossible to selectively gidrirovanii benzene from a mixture of hydrocarbons containing the toluene and the xylenes, it is necessary, therefore, if you want to convert only benzene, tentative is but to fractionate the mixture thus in order to isolate the fraction containing only benzene, which then can be gidrirovannah.

One solution to selectively reduce the benzene content in the hydrocarbon fraction, described in the patent EP 0781830. This patent relates to a method of purifying raw material, formed mostly of hydrocarbons containing at least 5 carbon atoms in the molecule, and containing at least one unsaturated compound containing at most six carbon atoms in the molecule, including benzene, in which the specified raw materials are treated in a distillation zone comprising depleted zone and a rectification zone, attached to the reaction zone hydrogenation, at least partially external to the distillation zone containing at least one catalytic layer. Raw materials from the reaction zone are selected on the height of the level of selection, while the effluent of the reaction zone, at least partially, re-introduced into the distillation zone at the height of at least level re-introduction thus, in order to ensure continuity of distillation, and thus to obtain in the end at the top of the distillation zone effluent, very depleted in unsaturated compounds containing at most six carbon atoms in the molecule, and at the bottom of the distillation zone effluent depleted in unsaturated with what disiniame, containing at most six carbon atoms in the molecule.

The disadvantage of this technology is that it provides clean only product of reforming, the resulting catalytic processing of oil, or it is also necessary to reduce the amount of light unsaturated compounds, particularly benzene, in the aggregate fractions that can be included in the gasoline pool without increasing costs associated with the stage of distillation.

Thus, an object of the present invention is the elimination of one or more of the disadvantages of the prior art by offering a way to produce with lower costs, on the basis of various hydrocarbon fractions, the product is depleted in unsaturated compounds, particularly benzene, or, if necessary, completely free of unsaturated compounds, particularly benzene, without significant loss of yield and with very little loss of octane number.

For this purpose, the present invention provides a method of processing raw material, formed mostly of hydrocarbons containing at least 4 carbon atoms in the molecule, and containing at least one unsaturated compound, including benzene, such that the raw materials are treated in a distillation zone, the depletion zone and the zone of rectification, combined with the reaction zone of the Hydra is the formation, at least partially external to the distillation zone containing at least one catalytic layer, in which the hydrogenation of at least part of the unsaturated compounds contained in the feedstock, in the presence of a hydrogenation catalyst and a gas stream containing hydrogen, the raw materials were taken from the reaction zone at a height of at least level selection in the distillation zone, the effluent of the reaction zone, at least partially, re-introduced into the distillation zone at the height of at least the level of re-introduction, to ensure continuity of distillation and get at the top of the distillation zone in a side drainage, located above the return line from the reaction zone to the distillation zone, and at the bottom of the distillation zone effluent depleted in unsaturated compounds, and this method differs in that it includes processing at least one of the second raw material containing at least one unsaturated compound, including benzene, at least partially, directly injected into the reaction zone hydrogenation, external to the distillation zone.

According to one variant of the method, the side selection is performed above the return line of the reaction zone.

According to another variant of the method, the side selection made is tlaut below the return line of the reaction zone.

According to another variant of the method, the second raw material Inuktitut with addition, injected into the internal area of the hydrogenation of distillation columns.

According to one variant of the method, the second raw material is formed by at least one hydrocarbon containing at least 4 carbon atoms in the molecule.

According to one variant of the method, the second raw material is formed by a faction With₅/S₆type of light oil direct distillation (straight run) and/or type of oil obtained in the hydrocracking and/or fractions enriched in benzene and/or toluene and depleted in sulphur and nitrogen, the resulting catalytic cracking, and/or gasoline fractions, representing the fraction enriched with benzene and/or toluene and depleted in sulphur and nitrogen, produced coking or installing a light cracking, and/or fractions enriched in benzene and/or toluene and depleted in sulfur and nitrogen, obtained after cracking of olefins or oligotrichida, and/or fractions enriched in benzene and/or toluene and depleted in sulphur and nitrogen, generated at the plant for the production of olefins by cracking in the vapor phase.

According to another variant of the method, the second material is at least one fraction selected among:

-hydrocarbons, containing at least 4 carbon atoms in the molecule,

- faction With₅/S₆type of light oil direct distillation (straight run),

- faction With₅/S₆type of oil obtained by hydrocracking unit

average gasoline fractions of a catalytic cracking oil, enriched with benzene in relation to the catalytic cracking gasoline,

- fraction of light gasoline installation coking enriched with benzene to all gasoline installation coking,

- fractions enriched in benzene, obtained after separation and hydrobromide gasoline obtained by cracking of olefins or oligotrichida,

- fractions enriched in benzene, leaving the plant for producing olefins by cracking in the vapor phase.

According to one variant of the method, the distillation is carried out at a pressure in the range from 0.2 to 2 MPa, with a reflux ratio in the range from 0.5 to 10, with temperatures in the upper part of the distillation zone is in the range from 40 to 180°C., and the temperature at the bottom of the distillation zone is in the range from 120 to 280°C.

According to one variant of the method, the reaction zone hydrogenation is entirely external to the distillation zone.

According to one variant of the method, part effluent the reactor, the hydrogenation return to the reactor inlet.

According to one variant of the method, the reaction zone hydrogenation is also partly included in the area distillation area distillation and partially external to the distillation zone.

According to one variant of the method, the hydrogenation reaction carried out in part of the hydrogenation zone, internal zone of the distillation is carried out at a temperature in the range from 100 to 200°C., a pressure in the range from 0.2 to 2 MPa, space velocity in the medium of the inner zone hydrogenation reactions, calculated with respect to the catalyst being in the range from 1 to 50 h^-1and the consumption of hydrogen, the supply zone hydrogenation reactions, which is in the range from 0.5 times to 10 times the flow rate corresponding to the stoichiometry flowing hydrogenation reactions.

According to another variant of the method, the hydrogenation reaction carried out in the outer part of the zone of the distillation is carried out at a pressure in the range from 0.1 to 6 MPa, the temperature being in the range from 100 to 400°C., space velocity in the medium zone hydrogenation reactions, calculated with respect to the catalyst, which is usually in the range from 1 to 50 h^-1and the consumption of hydrogen in the range from 0.5 times to 10 times the flow rate is, the corresponding stoichiometry flowing hydrogenation reactions.

According to one variant of the method, carry out stage isomerization feedstock to the reaction zone, taken at a height of at least level selection in the zone of distillation.

According to one variant of the method, the stage of isomerization is carried out in a hydrogenation reactor at the same time that the hydrogenation reaction.

According to one variant of the method, the stage isomerization carry out the hydrogenation reactor and after the stage of hydrogenation.

According to one variant of the method, the hydrogenation catalyst is in contact with a descending liquid phase and an ascending vapor phase for the entire catalytic layer inner part of the zone hydrogenation reactions.

According to one variant of the method, the gas stream containing the hydrogen necessary for the reaction zone hydrogenation, combined with the vapor phase is sensitive to the input of at least one catalytic layer zone hydrogenation reactions.

According to one variant of the method, the leakage of liquid subject to hydrogenation, and a gaseous stream containing hydrogen occurs in the matching threads for the entire catalytic layer inner part of the zone hydrogenation reactions.

According to one variant is sushestvennee way the leakage of liquid subject to hydrogenation, and a gaseous stream containing hydrogen, is in matching the threads is such that the steam distillation never comes into contact with the catalyst for the entire catalytic layer inner part of the zone hydrogenation reactions.

According to one variant of the method, any catalyst used in the reaction zone hydrogenation comprises at least one metal selected in the group formed by Nickel, zirconium, and platinum.

According to one variant of the method, the metal is on the media of chlorinated alumina or zeolite, aluminum oxide.

The invention applies equally, the application of the method to produce raw materials for isomerization of paraffins best quality.

Other characteristics and advantages of the invention will be better understood and will appear more clearly when reading the following description made with reference to the accompanying drawings and data as example:

- Fig.1 is a schematic illustration of the method according to the invention reduce the amount of light of unsaturated compounds in hydrocarbon fractions,

- Fig.2 is a schematic illustration of one variant of the method according to the invention reduce the amount of light unsaturated with what dinani in hydrocarbon fractions,

- Fig.3 is a schematic illustration of another embodiment of the method according to the invention reduce the amount of light of unsaturated compounds in hydrocarbon fractions.

The method according to the invention, illustrated in Fig.1-3, is to reduce the amount of light unsaturated compounds containing from 6 to 12 carbon atoms, including benzene, in various hydrocarbon fractions. Thus, the method allows to produce a fuel, in particular gasoline, benzene content which is reduced in such a way as to comply with the current norms, still retaining a good octane number.

A method of reducing the amount of light unsaturated compounds according to the invention includes the operation of distillation, the operation of the hydrogenation and, in some cases, the operation of the isomerization, organized and carried out in such a way as to minimize the investment costs of a way to maximize conversion of unsaturated products, minimizing the consumption of hydrogen and maximizing the yield of distillate and residue coming out of the column, with an adequate content of benzene in the lungs unsaturated compounds, including benzene.

The method according to the invention is a method of processing at least one raw material, formed mostly of hydrocarbons, which terashima, at least 4, preferably from 5 to 12 carbon atoms in the molecule, and containing at least one light unsaturated compound, in particular benzene. The purified fractions are, for example:

- reforming product resulting from the catalytic purification of oil intended for the preparation of aromatic hydrocarbons containing mainly from 4 to 12 carbon atoms in their molecule, a very high octane number which gives the gasoline antiknock properties

- faction With₅/S₆such as:

CH light oil direct distillation (Light Straight Run),

GL oil obtained by hydrocracking unit.

The average benzene content in these fractions are, in order of magnitude, from 2 to 10 vol.% accordingly, the cleaned crude oil and the temperature of the fraction.

These fractions do not contain or contain little olefins, and their joint processing in the unit of hydrogenation of benzene does not lead to a significant increase in loss of octane number or consumption of hydrogen, in addition to those associated with the hydrogenation of benzene,

- the other factions emerging from the catalytic cracking unit or fluid catalytic cracking FCC (Fluid Catalytic Cracking according to English terminology) and light gasoline from the unit coking unit (coker according to English terminology), set the Cai delayed coking unit, install the fluid catalytic cracking unit, or installation of coking type Flexicoker, or install a light cracking (visbreaking according to English terminology),

These fractions are always olefin and often rich in heteroatoms (sulfur, nitrogen, chlorine) that are harmful to catalysts for the hydrogenation of benzene. They often require pre-treatment prior to introduction into the installation hydrogenation of benzene. In addition, the contents depend on the temperature of the fraction and properties of the raw material primary unit conversion (FCC or coker or visbreaker). These contents are typically approximately 2 to 10 vol.%, even more, if you consider a narrow faction

- fractions enriched in benzene or other light unsaturated compounds, obtained after separation and hydrobromide gasoline resulting from the cracking of olefins (cracking of olefins With₄-C₁₀to ethylene and propylene in the acidic catalyst)

- fractions enriched in benzene, from plant production of olefins, the type of cracking in the vapor phase (Pyrolysis gasoline according to English terminology), or coke ovens (Coke Oven Light Oil according to English terminology).

The first implementation of the method shown in Fig.1. Raw materials, formed crude product of reforming, usually containing small amounts of hydrocarbons With_4-send the distillation column (2) line (1). The distillation column (2) contains depleted zone and the zone of rectification connected with area hydrogenation reactions. Thus, the distillation zone comprises, generally, at least one column, provided with at least one internal device for distillation, selected in the group formed by the plates, random packings and structured packings (shown partially in dashed lines on Fig.1), and, as is well known to specialists in this area, such that the total overall efficiency is at least equal to five theoretical stages.

In this embodiment, the reaction zone hydrogenation is completely external to the distillation zone.

Raw material that feeds the distillation zone, introducing into the specified area of the distillation, usually at least at the level of the specified zone, preferably mainly on a single level of the specified area.

At the bottom of column (2) of the least volatile part of the raw material, formed mainly of hydrocarbons with 7 or more carbon atoms (fraction₇₊), delete line (5), re-boil in the heat exchanger (or furnace) 6 and is removed by line 7. The secondary product boiling again injected into the column through line (8). In the upper part of the column, light distillate, containing, mainly, from 4 to 7 carbon atoms the molecule (fraction _7-), preferably, in the main, from 4 to 6 carbon atoms in the molecule (fraction_6-), direct line (9) into the condenser (10), then the vessel of the separator (11), in which there is a separation of the liquid phase and the vapor phase formed mainly by hydrogen, possibly in excess. Vapour phase away from the vessel through line (14). The liquid phase from the vessel (11) again directed, in part, through line (12) in the upper part of the column, to ensure the return of the distillate in the form of phlegmy, while the other part forms a liquid distillate, which is removed through line (13).

Light distillate can also be assembled in side fluid extraction (not shown) from the column without further transmission through the vessel of the separator in order to remove the majority of lung connection_4-and to provide sufficient vapor pressure.

Using either a plate selection, located in the zone of rectification, or, if desired, the plate sections of the exhaustion of the column line (15A) divert fluid, which is sent to the hydrogenation reactor 3A through the top according to Fig.1, or through the bottom, after the addition of hydrogen along the lines of (4) then (4A), or directly into the reactor. Effluent hydrogenation reactions return to the column line (16A), which is located either above the line selection 15A, as shown in Fig.1, or below the line selection (15A).

In the embodiment, is provided in Fig.1A, the device comprises a second external hydrogenation reactor. Line (15b) divert fluid, which is sent to the hydrogenation reactor (3b), after addition of the hydrogen lines (4) and (4b), or directly into the reactor, and return it to the column line (16b), which is located either above the line selection (16A), as shown in Fig.1, or below the line selection (16A).

In this case, the stage hydrogenation is carried out in the two outer zones hydrogenation reactions.

For each reactor may be a selection effluent (not illustrated), for example, to nourish another reaction section, such as section isomerization of paraffins.

According to another variant implementation, not shown, the method comprises a stage of hydrogenation is carried out in one of the outer zone of the hydrogenation reactions.

The gas flow discharged from the vaporous distillate distillation column, containing, perhaps, an excess of hydrogen, after re-compression can be re-directed back to the reactor to minimize the consumption of the hydrogen system (not shown).

According to another variant of the method shown in Fig.2, raw materials, formed crude product of reforming, (C₄₊), usually containing small amounts of hydrocarbons With_4-direct on line (1) to a distillation column (2), sabien the Yu internal devices for distillation, which represents, for example in the case of Fig.2, a plate distillation column, and the catalyst layer (3) containing a hydrogenation catalyst and fed with hydrogen through line (4).

In this embodiment, the reaction zone hydrogenation is at least partially external to the distillation zone. As in the previous embodiment, the distillation zone can be divided into two columns. In practice, when the reaction zone hydrogenation is at least partially internal to the distillation zone, a rectification zone or zone of exhaustion and, preferably, the area of exhaustion might be at least in the same column different from the column containing the inner part of the reaction zone hydrogenation.

Area hydrogenation reactions, similarly, may be partially included in the area distillation area distillation and partially external to the distillation zone.

Affluent upper and lower parts of the column are treated as described above for the first variant implementation of the method. With plates selection, located in the zone of the rectification column, line (15C) are selected liquid, which, after addition of the hydrogen lines (4C), is introduced into the hydrogenation reactor 3C. Effluent of the hydrogenation reactor returned to the distillation column by Lin and (16C), which is located either above the line selection 15C, as shown in Fig.2, or below the line selection (15C). It is in this area hydrogenation reactions (3C) hydrogenation is carried out at least part of the unsaturated compounds containing at most six carbon atoms in the molecule, i.e. containing up to six (including) of carbon atoms in the molecule, and are contained in raw materials.

In General, the method contains from 1 to 6, preferably from 1 to 4 levels of selection, which(e) powers(comply) with the outer portion of the hydrogenation zone. Part of the external part of the hydrogenation zone contains, typically, at least one reactor. If the outer part contains at least two catalytic layer, placed in at least two reactors, these reactors arranged in series or in parallel, and each of these reactors, preferably, is fed from the level of selection that is different from the level of selection from which is fed by the other(s) to the reactor(s).

Area hydrogenation reactions contains, typically, at least one catalytic layer hydrogenation, preferably, from 2 to 4 catalytic layers. In the reaction zone of the hydrogenation is carried out at least partially, the hydrogenation of benzene present in the faction, usually, so that the content of benzene in effluent the upper part would be in the highest degree is equal to the specific content of aniu, and in this zone the hydrogenation reaction is carried out at least partially, preferably, in the most part, the hydrogenation of any unsaturated compounds containing at most six carbon atoms in the molecule and different from benzene may also present in the fraction.

When the zone hydrogenation reactions simultaneously partially included in the zone of distillation, that is internal to the distillation zone and partially external to the distillation zone, the reaction zone hydrogenation contains at least two, preferably at least three catalytic layer, with at least one catalytic layer is internal to the distillation zone and at least one catalytic layer is external to the distillation zone. When the outer portion of the hydrogenation zone contains at least two catalytic layers, each catalytic layer is fed from one level of selection, preferably associated with one level of re-introduction, and the specified level of selection is different from the level selection, which nourishes the other(s) of catalyst(s) layer(s). Typically, the fluid is subject to hydrogenation, either partially or fully, is circulated first in the outer part of the hydrogenation zone, then in the inner part of the specified zone Hydra the simulation. For part of the zone hydrogenation reactions, internal to the distillation zone, the fluid extraction is a natural expiration of part of the reaction zone, internal to the distillation zone, and re-introduction of liquid into the distillation zone is also a natural outflow of liquids from the reaction zone hydrogenation, internal to the distillation zone. In addition, the process preferably is such that after gidriruemyi fluid is carried out in a matching thread, or in countercurrent, preferably in a matching thread with a gaseous stream containing hydrogen, for all catalytic layer inner part of the hydrogenation zone, more preferably such that the flow gidriruemyi fluid is coincident stream with a gas stream containing hydrogen, so that the steam is separated from the specified fluid for the entire catalytic layer inner part of the hydrogenation zone.

The invention consists in that the reaction zone hydrogenation feed two different factions, subject to hydrogenation.

The first fraction, subject to hydrogenation, as already described in the patent EP 0781830, formed by the fraction taken from the distillation column (2). This first fraction, subject to hydrogenation of selected lines (15A, b or C) at the height of the level of selection is from the Oh, at least partially, preferably, for the most part, the liquid flowing in the distillation zone, preferably, the current in the rectification zone, more preferably, the current at the intermediate level of the rectification zone. Preferably, the current level at least 2 plates, very preferably at least 10 plates from the top and bottom of the column.

The second faction, subject to hydrogenation, Inuktitut directly in the outer part of the distillation zone above the reaction zone hydrogenation on line (17c), or in the inner part of the line (17d), or directly into the reaction zone hydrogenation, when she is completely external to the distillation column, lines (17A, b), in particular in the hydrogenation reactor.

This second fraction can be injection, at least partially, or fully, into the reaction zone hydrogenation, external to the distillation column.

When it Inuktitut at least partially, the injection box can be done with addition, injected into the inner zone hydrogenation reactions.

The second fraction may be injection lines (17A, b, C or d) after pre-mixing with the first fraction, selected lines (15A, b or C), and adding hydrogen lines (4A, b, C), as shown in Fig.1 and 2.

Another options is the ant of the invention, the second fraction may be injection one, after adding hydrogen, i.e. without pre-mixing with the first fraction (not shown).

This second group can be characterized by the absence or low content of heavy unsaturated compounds, which wish to save. It can be formed by any of the following fractions enriched in benzene and/or aromatic compounds that are heavier than benzene, compared with the untreated gasoline fractions originating from the considered methods, and depleted in sulfur, nitrogen and chlorine through hydrobromide:

- easy reforming product resulting from the catalytic purification of oil intended for the preparation of aromatic hydrocarbons containing, mainly, from 4 to 7 carbon atoms in their molecule (fraction_7-With_6-very high octane number which gives the gasoline antiknock properties

- faction With₅/S₆such as:

CH light oil direct distillation (Light Straight Run),

GL oil obtained by hydrocracking unit.

The average benzene content in these fractions are, in order of magnitude, from 2 to 10 vol.% accordingly, the nature of the crude oil from which they originated, temperatures fractions

- other fractions enriched in benzene, distillerie is and hydrobromide and leaving the catalytic cracking unit or fluid catalytic cracking FCC (Fluid Catalytic Cracking according to English terminology) and light gasoline from the unit coking unit (coker according to English terminology), delayed coking unit, installation, fluid catalytic cracking, or installation of coking type Flexicoker, or install a light cracking (visbreaking according to English terminology),

- fractions enriched in benzene, obtained after separation and hydrobromide gasoline resulting from the cracking of olefins (cracking of olefins With₄-C₁₀to ethylene and propylene in the acidic catalyst)

- fractions enriched in benzene, from plant production of olefins, the type of cracking in the vapor phase (Pyrolysis gasoline according to English terminology), or coke ovens (Coke Oven Light Oil according to English terminology) after distillation and hydrobromide.

The advantage of this alternative implementation is that the method allows thus to clear the largest number of fractions of different origin without special material costs and the obvious additional costs. In fact, the second fraction or the second fraction, subject to hydrogenation, directly injected into the hydrogenation reactor without prior passage through the distillation column, or introduced into the distillation zone in place, preferable from the point of view of their boiling points. Therefore, not required, or you need a small additional energy consumption that occurs when the colon is s, evaporator and condenser.

Another advantage arises because, given that the hydrogenation of benzene leads to the loss of octane number, it is often advantageous to direct the hydrogenated distillate in the isomerization of paraffins. Conventional distillation cannot be removed in the distillate, the basic amount of benzene, not to be swept into the distillate with a few % With₇(typically, 3% and more). Connection₇as cyclohexane, resulting from the hydrogenation of benzene, are inhibitors of the isomerization catalyst, increase the consumption of hydrogen and reduce the volume yield of isomerization in the reactions of hydrocracking. In the method according to the invention, the hydrogenation of benzene in the side or internal reactor relative to the column, allows you to break the azeotrope between compounds With₇and benzene and removing a portion of the cyclohexane from the bottom of the column, which allows to obtain the fraction of the best quality for the isomerization unit.

According to another variant embodiment of the invention depicted in Fig.3, the method comprises a stage isomerization fraction of the reaction zone, taken at a height of at least level selection in the distillation zone. According to a variant implementation, shown in Fig.3, this phase of the isomerization is carried out after the stage hydrogenation. It p is avodat in the reactor, well-known specialists in this field. In this case, line (15C) are selected liquid, which, after addition of the hydrogen lines (4C), is introduced into the hydrogenation reactor (3C). The second faction, subject to hydrogenation, Inuktitut directly in the outer part of the distillation zone above the reaction zone hydrogenation on line (17c). Effluent of the hydrogenation reactor is sent then to the isomerization reactor (3i), then returned to the distillation column through line (16i), which is located either above the line selection (15C), as shown in Fig.3, or below the line selection (15C). Light distillate taken from the side line (13). This selection can be made either below the return from the polymerization reactor by line 16i (as shown in Fig.3) or above (not shown in Fig.3) return from the polymerization reactor by line 16i. Line 121 is used to control the pressure of steam by extracting fluid. This fluid could be subsequently evaluated.

According to another variant not illustrated, the isomerization reaction can proceed in the same reactor, the hydrogenation reaction. When the isomerization reaction proceeds in the hydrogenation reactor, the reaction is carried out either at the same time, or after hydrogenation, for example using two consecutive layers, which are sequentially arranged catalyst g is tiravanija and the isomerization catalyst.

As described before, the area hydrogenation reactions may be completely external to the distillation zone, or partially external. In this case, the isomerization reaction, when it flows in the same reactor, the hydrogenation reaction occurs in the part of the hydrogenation zone, external to the distillation zone.

When the method uses two reactor hydrogenation, isomerization reaction can be carried out in each of the two hydrogenation reactors, or may be carried out in two reactors isomerization, each of which is followed by a hydrogenation reactor (not shown). Thus, the method may include two-stage isomerization, when there are two stage hydrogenation.

This stage isomerization can improve the octane number of the fractions obtained.

The method is concerned, therefore, reactions that produce one or more products having a boiling point below and/or almost identical to the boiling temperature of the reactants, in particular, the case of the hydrogenation of olefins having at most six carbon atoms in their molecule, and benzene in the light fraction product of the reformer (see table 1 below). In this fraction, olefins usually have an extensive character, and the corresponding alkanes are lighter than these olefins. Benzene, another agent in this form, the shares very little difference in boiling point from the main reaction product of its hydrogenation and cyclohexane (the difference between the evaporating temperature of 0.6°C). Consequently, when the conditions necessary to ensure that the heavier products remained in the lower part of the column, cyclohexane usually distributed between affluently upper and lower parts of the column. The other products formed in the reaction of hydrogenation of benzene is Methylcyclopentane. This product is especially favoured by the hydrogenation catalysts having high acidity. When the isomerization is carried out in a hydrogenation reactor, one of the particularly preferred catalysts according to the invention is platinum on chlorinated and/or fluorinated alumina. This type of catalyst has a relatively high acidity and, therefore, promotes hydrogenation reactions with isomerization of benzene in Methylcyclopentane, which is characterized by a boiling point much lower boiling point of benzene.

Another type of catalyst that can be used in the framework of the invention for the isomerization reactions, contains at least one metal selected from among Nickel, zirconium, and platinum, and the metal supported on a carrier of chlorinated alumina or zeolite hydroxy is and aluminium. This type of catalyst may be used as a catalyst for the hydrogenation and isomerization, when stage isomerization takes place in the same reactor, the reactor stage hydrogenation, or may be used in addition to the hydrogenation catalyst, if both reactions take place not in the same reactor.

The method according to the invention allows thus to gidrirovanii most of the connection(s), subject to(their) hydrogenation, outside the zone of distillation, it is possible, under conditions of pressure and/or temperature, are different from the conditions used in the column.

The hydrogenation reaction is exothermic reaction. In some cases, the amount of hydrogenation reactors is important. To limit evaporation effluent this reaction, can be advantageous to carry out the hydrogenation reaction zone, located outside of the column at a higher pressure than the pressure within the distillation zone. This increase in pressure also increases the dissolution of a gas stream containing hydrogen, in the liquid phase containing the compound (or compounds), subject(s) hydrogenation.

According to another variant of the invention, part effluent reactor may be returned directly to the inlet of the hydrogenation reactor without passing through the column and after the possible removal of the gas fraction (not shown).

The method is such that leakage of liquid subject to hydrogenation occurs in a matching thread to the expiration of the gaseous stream containing hydrogen, for all catalytic layer outer part of the hydrogenation zone

For the implementation of the hydrogenation, theoretical molar ratio of hydrogen required for the desired conversion of benzene, is equal to 3. The amount of hydrogen, distributed through, or in the hydrogenation zone is probably in excess relative to the stoichiometry, the more that we should gidrirovanii, in addition to benzene that is present in the faction, at least partially, any unsaturated compound containing at most nine carbon atoms in the molecule, preferably at most 7 carbon atoms, more preferably at most 6 carbon atoms, and is present in the specified faction. The excess hydrogen, if it exists, can be advantageously removed, for example, according to one of the methods described below. According to the first method, the excess of hydrogen, which comes from the reaction zone hydrogenation, isolated after separation of the liquid fraction coming from the reactor, then compress and re-use in said reaction zone.

According to the second method, the excess of hydrogen, which comes from the reaction zone, allocate, then Inuktitut higher stages of compression associated with the installation of catalytic reforming, in a mixture with hydrogen originating from this setup, and this facility operates, preferably at low pressure, that is, typically, at a pressure of less than 8 bar (1 bar = 10 PA).

According to the third method, the excess of hydrogen in the reaction section is extracted in a pair of distillate, then re-compress to re-inject above the reactor or directly into the reactor.

The hydrogen contained in the gas stream used in the method according to the invention for hydrogenation of unsaturated compounds, it can come from any source, producing hydrogen with a purity of at least 50 vol.%, preferably with a purity of at least 80 vol.%, more preferably, a purity of at least 90 vol.% For example, you can call the hydrogen originating from a catalytic reforming process, mahanirvana, P. S. A (adsorption alternating pressure), electrochemical generation of cracking in the vapor phase.

One of the preferred embodiments of the method, independent or not from the previous embodiments, such that effluent bottom of the distillation zone mix, at least partially, with effluent the upper part of this zone. The mixture, thus obtained, may, after stabilization, to be used as fuel, either directly or by introducing into fuel fractions.

When the hydrogenation zone is at least partially included in the zone of distillation, catalytic hydrogenation can be placed in the parts included with the according to different technologies, proposed for catalytic distillation. They are essentially of two types.

According to the first type of technology, reaction and distillation occur simultaneously in the same physical space, as recommended, for example, patent application WO-A-90/02.603, for example, patents US-A-4471154 or US-A-4475005. In this case, the catalyst generally is in contact with the flowing liquid phase generated by the phlegm introduced into the top of the distillation zone, and with the ascending vapor phase generated steam evaporator is introduced into the lower part of the zone. According to this type of technology, the gas stream containing the hydrogen required in the reaction zone for implementing the method according to the invention, could be connected with a steam phase is almost at the entrance to the at least one catalytic layer of the reaction zone.

The second type of technology, the catalyst is placed in such a way that the reaction and distillation occur, usually, independent and consistent manner, as recommended, for example, patents US-A-4847430, US-A-5130102 and US-A-5368691, while shepherd pairs practically does not intersect any of the catalytic layer of the reaction zone. Thus, if you use this type of technology, the process is usually such that the expiration gidriruemyi fluid occurs in the overlapping stream after the gas stream, with the containing a series of hydrogen, so that even surpass couples never comes into contact with a catalyst (which is usually expressed in practice in the fact that the steam is separated from the specified gidriruemyi liquid) for any catalytic layer inner part of the hydrogenation zone. Such systems typically contains at least one device for distributing fluid, which may be, for example, liquid distributor, in any catalytic layer of the reaction zone. However, the extent to which these technologies were designed for catalytic reactions between reactive liquids, they may not be suitable without modification for catalytic hydrogenation reactions, for which one of the reactants, hydrogen is gaseous. Consequently, any catalytic layer of the inner part of the hydrogenation zone is usually necessary to provide a device for distribution of a gas stream containing hydrogen, for example, according to one of the three methods described below.

Thus, the inner part of the hydrogenation zone contains at least one device for distributing fluid and at least one device for distribution of a gas stream containing hydrogen, in any catalytic layer of the hydrogenation zone, internal to the distillation zone. According to the first method is ke, device for distribution of a gas stream containing hydrogen, is in front of the device for distributing the liquid, and, therefore, before the catalyst layer. According to the second method, a device for distribution of a gas stream containing hydrogen, is located at the device level for the distribution of liquid so that the gas stream containing hydrogen, is introduced into the liquid before the catalytic layer. According to the third method, a device for distribution of a gas stream containing hydrogen, are placed after the fixtures for the distribution of liquid and, consequently, in the environment of the catalytic layer, preferably, not far from the specified device for the distribution of liquid in the specified catalytic layer. The terms "before" and "after" used before that, understood in relation to the direction of fluid circulation, which will pass through the catalytic layer.

One implementation of the method is that the catalyst inner part of the hydrogenation zone is placed in the reaction zone according to the basic device described in patent US-A-5368691 which is arranged in such a way that any catalytic layer of the inner part of the hydrogenation zone is fed with a gas stream containing hydrogen, evenly distributed on its core the of, for example, according to one of the three techniques described above.

When the hydrogenation zone is at least partially internal to the distillation zone, the operating conditions of hydrogenation, internal to the distillation zone, associated with the working conditions of distillation. For example, the distillation can be carried out in such a way that its lower product contains most of cyclohexane and isoparaffins to 7 carbon atoms from the faction, as well as cyclohexane, resulting from the hydrogenation of benzene. It is carried out at a pressure which is typically in the range of from 0.2 to 2 MPa, preferably from 0.4 to 1 MPa, with a reflux ratio in the range from 1 to 10, preferably in the range from 3 to 6. The temperature of the upper part of the zone is usually in the range from 40 to 180°C., and the temperature of the lower part of the zone is usually in the range of from 120 to 280°C. the hydrogenation Reaction is carried out in conditions which in the most General case is intermediate between the conditions imposed at the top and bottom of the distillation zone, at a temperature in the range from 100 to 250°C., preferably in the range from 120 to 220°C. and a pressure in the range from 0.2 to 2 MPa, preferably from 0.4 to 1 MPa. The spatial velocity inside this area guy who compete, calculated in relation to the catalyst, is generally in the range from 1 to 50 h^-1in particular, from 1 to 30 h^-1(the amount of raw materials to the volume of catalyst per hour). The consumption of hydrogen is in the range from 0.5 times to 10 times the flow rate corresponding to the stoichiometry flowing hydrogenation reactions, preferably from 1-fold to 6-fold flow corresponding to the specified stoichiometry, more preferably, from 1-fold to 3 times the flow rate corresponding to the specified stoichiometry. The liquid is subjected to hydrogenation, feed gas stream containing hydrogen, the flow rate of which depends on the concentration of benzene in the specified fluid and, in General, unsaturated compounds containing at most six carbon atoms in the molecule, at a fraction of the distillation zone. Usually, it is at least equal to the flow rate corresponding to the stoichiometry flowing hydrogenation reactions (hydrogenation of benzene and other unsaturated compounds containing at most six carbon atoms in the molecule contained in gidriruemyi faction) and, at most, equal to the flow rate corresponding to 10 times the stoichiometric, preferably in the range from 1-fold to 6-fold stoichiometric, more preferably in the range from 1-fold to 3-fold stoichiometric.

In the outer part of the zone hydrogenation catalyst is any catalyst layer according to any technology, well-known experts in this field, in the working conditions (temperature, pressure...), independent or not, preferably independent from the operating conditions of the distillation zone.

In part of the hydrogenation zone, external to the distillation zone, the operating conditions are usually the following. The pressure required for this stage hydrogenation is usually in the range from 0.1 to 6 MPa, preferably from 0.2 to 5 MPa, more preferably from 0.5 to 3.5 MPa.

The working temperature of the hydrogenation zone is usually in the range from 100 to 400°C., preferably from 110 to 350°C., more preferably from 120 to 320°C. the Spatial velocity within the specified hydrogenation zone, calculated with respect to the catalyst, is generally in the range from 1 to 50, in particular from 1 to 30 h^-1(the amount of raw materials to the volume of catalyst per hour). The consumption of hydrogen is in the range from 0.5 times to 10 times the flow rate corresponding to the stoichiometry of the reactions occurring preferably from 0.4 to 1 MPa, from 0.2 to 2.50 MPa fitted in the upper and lower parts of the hydrogenation, preferably from 1-fold to 6-fold flow corresponding to the specified stoichiometry, more preferably, from 1-fold to 3 times the flow rate corresponding to the specified stoichiometry. But the conditions of temperature and pressure may also, in the framework of the method according to the but the present invention to be in the range between conditions that are installed in the top and bottom of the distillation zone.

In General, whatever the position of the hydrogenation zone to the distillation zone, the catalyst used in the hydrogenation zone by the method according to the present invention includes, generally, at least one metal selected in the group formed by Nickel and platinum are used as is, or, preferably, supported on a carrier. The metal should, typically, be in restored form, at least 50 wt.% from his total. But any other hydrogenation catalyst known to specialists in this field can be selected in the same manner.

When using the platinum catalyst may contain, preferably, at least one halogen in the mass content in relation to the catalyst being in the range from 0.2 to 2%. Preferably, use a chlorine or fluorine, or a combination of both in content relative to the total weight of the catalyst being in the range from 0.2 to 1.5%. In the case of using a catalyst containing platinum, typically use such a catalyst, the average size of the crystallites of platinum is less than 60·10^-10m, preferably less than 20·10^-10m, more preferably less than 10·10^-10M. in Addition, the total content is their platinum relative to the total weight of the catalyst is, usually, in the range from 0.1 to 1%, preferably, 0.1 to 0.6%.

In the case of Nickel, the Nickel content relative to the total weight of the catalyst is in the range from 5 to 70%, in particular from 10 to 70%, preferably from 15 to 65%. In addition, typically use such a catalyst, the average crystallite size of Nickel is less than 100·10^-10m, preferably less than 80·10^-10m, more preferably less than 60·10^-10m

The carrier is usually chosen in the group formed by alumina, aluminosilicates, silica, zeolites, activated carbon, clays, alumina cement, rare earth oxides and oxides of the alkaline earth elements, individually or in mixture. Preferably, use a carrier based on alumina or silica with a specific surface area in the range from 30 to 300 m²/g, preferably from 90 to 260 m²/year

1. The method of processing two fractions of raw materials, in which the first raw material is formed predominantly of hydrocarbons containing at least 4 carbon atoms in the molecule, and contains at least one unsaturated compound, including benzene, such that the first raw material is treated in a distillation zone, the depletion zone and the zone of rectification, combined with the reaction zone hydrogenation, at least partially, outside the it to the distillation zone, containing at least one catalytic layer, in which the hydrogenation of at least part of the unsaturated compounds contained in the first raw material, in the presence of a hydrogenation catalyst and a gas stream containing hydrogen, with the first raw material is withdrawn from the reaction zone by at least the height of the level selection in the distillation zone, while the effluent of the reaction zone, at least partially, re-introduced into the distillation zone at least at the height of the level of re-introduction, to ensure continuity of distillation and get at the top of the distillation zone, the side outlet in the distillation zone, and at the bottom of the distillation zone effluent depleted in unsaturated compounds, and this method differs in that it includes processing at least one of the second raw material containing at least one unsaturated compound, including benzene, at least partially, directly injected into the reaction zone hydrogenation, external to the distillation zone, while in the second raw average levels of benzene ranges from 2% to 10 volume%.

2. The method according to p. 1, in which the side selection is performed above the return line of the reaction zone.

3. The method according to p. 1, in which the side selection is performed below the return line of the reaction zone.

4. Pic is b in one of the paragraphs.1-3, in which the second raw material Inuktitut with addition, injected into the internal area of the hydrogenation of distillation columns.

5. The method according to one of paragraphs.1-3, in which the second raw material is formed by at least one hydrocarbon containing at least 4 carbon atoms in the molecule.

6. The method according to one of paragraphs.1-3, in which the second raw material is formed by fraction C₅/S₆type of light oil direct distillation (straight run) and/or type of oil obtained in the hydrocracking and/or fractions enriched in benzene and/or toluene and depleted in sulphur and nitrogen, the resulting catalytic cracking, and/or gasoline fractions, representing the fraction enriched with benzene and/or toluene and depleted in sulphur and nitrogen, produced coking or installing a light cracking, and/or fractions enriched in benzene and/or toluene and depleted in sulfur and nitrogen, obtained after cracking of olefins or oligotrichida, and/or fractions enriched in benzene and/or toluene and depleted in sulphur and nitrogen, generated at the plant for the production of olefins by cracking in the vapor phase.

7. The method according to one of paragraphs.1-3, in which the second material is at least one fraction selected among:
- hydrocarbons containing at least 4 carbon atoms in the molecule,
- fraction C 5/S₆type of light oil direct distillation (straight run),
- fraction C₅/S₆type of oil obtained by hydrocracking unit
average gasoline fractions of a catalytic cracking enriched in benzene relative to the catalytic cracking gasoline,
- fraction of light gasoline installation coking enriched with benzene to all gasoline installation coking,
- fractions enriched in benzene, obtained after separation and hydrobromide gasoline obtained by cracking of olefins or oligotrichida,
- fractions enriched in benzene, leaving the plant for producing olefins by cracking in the vapor phase.

8. The method according to one of paragraphs.1-3, in which the distillation is carried out at a pressure in the range from 0.2 to 2 MPa, with a reflux ratio in the range from 0.5 to 10, with temperatures in the upper part of the distillation zone is in the range from 40 to 180°C., and the temperature at the bottom of the distillation zone is in the range from 120 to 280°C.

9. The method according to one of paragraphs.1-3, in which the reaction zone hydrogenation is entirely external to the distillation zone.

10. The method according to one of paragraphs.1-3, in which part effluent reactor hydrogenation return to the reactor inlet.

11. The method according to p. 1, in which the reaction zone hydrogenation is simultaneously cha is partially included in the area distillation area distillation and partially external to the distillation zone.

12. The method according to p. 11, in which the hydrogenation reaction carried out in part of the hydrogenation zone, internal zone of the distillation is carried out at a temperature in the range from 100 to 200°C., at a pressure in the range from 0.2 to 2 MPa, space velocity in the medium of the inner zone hydrogenation reactions, calculated with respect to the catalyst being in the range from 1 to 50 h^-1and the consumption of hydrogen, the supply zone hydrogenation reactions, which is in the range from 0.5 times to 10 times the flow rate corresponding to the stoichiometry flowing hydrogenation reactions.

13. The method according to p. 1 in which the hydrogenation reaction carried out in the outer part of the zone of the distillation is carried out at a pressure in the range from 0.1 to 6 MPa, the temperature being in the range from 100 to 400°C., space velocity in the medium zone hydrogenation reactions, calculated with respect to the catalyst, which is usually in the range from 1 to 50 h^-1and the consumption of hydrogen in the range from 0.5 times to 10 times the flow rate corresponding to the stoichiometry flowing hydrogenation reactions.

14. The method according to one of paragraphs.1-3, in which stage isomerization feedstock to the reaction zone, taken at a height of at least level selection in the zone of distillation.

15. The method according to p. 14, in which oterom stage isomerization is carried out in a hydrogenation reactor at the same time, the hydrogenation reaction.

16. The method according to p. 14, in which stage isomerization carry out the hydrogenation reactor and after the stage of hydrogenation.

17. The method according to one of the p. 12 or 13, in which the hydrogenation catalyst is in contact with a descending liquid phase and an ascending vapor phase for the entire catalytic layer inner part of the zone hydrogenation reactions.

18. The method according to p. 17, such that the gas stream containing the hydrogen necessary for the reaction zone hydrogenation, combined with the vapor phase is sensitive to the input of at least one catalytic layer zone hydrogenation reactions.

19. The method according to one of the p. 11 or 12, in which the leakage of liquid subject to hydrogenation, and a gaseous stream containing hydrogen occurs in the matching threads for the entire catalytic layer inner part of the zone hydrogenation reactions.

20. The method according to one of the p. 11 or 12, in which the leakage of liquid subject to hydrogenation, and a gaseous stream containing hydrogen, is in matching the threads is such that the steam distillation never comes into contact with the catalyst for the entire catalytic layer inner part of the zone hydrogenation reactions.

21. The method according to p. 1, in which the catalyst used in the reaction zone hydrogenation comprises at least one metal selected from groups who, including Nickel, zirconium, and platinum.

22. The method according to p. 21, in which the metal is on the media of chlorinated alumina or zeolite, aluminum oxide.

23. Application of the method according to one of paragraphs.1-22 to improve the quality of raw materials for isomerization of paraffins.