JPH0137436B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a process for the continuous conversion of hydrocarbons, and more particularly to a process for the reforming of hydrocarbons, i.e. aromatic carbonization, in the temperature range from 480 to 600°C and in the presence of catalysts. A method for producing hydrogen, in which an initial charge consisting of hydrocarbons and hydrogen is
The flow is conducted through at least two reaction zones arranged in series and each of the fluidized bed type, with the charge flowing through each reaction zone in turn and the catalyst flowing through each of them from above, also in the form of a fluidized bed. It relates to a method in which the catalyst flows continuously to the bottom and passes through each reaction zone in turn, and the catalyst is continuously removed from the bottom of the last reaction zone through which the charge has passed and is sent into the regeneration zone.

Prior art and its problems In the prior art, the regenerated catalyst is subjected to a reduction treatment, in other words, in order to reduce certain oxides, especially metal oxides, present in the catalyst before reaching the first reaction zone. If so, it will be treated with hydrogen.

In the prior art, when operating in the reaction zone of a catalyst bed, the reduction is carried out at the head of the reactor, inside the reactor, or near the head of the reactor. The heating of the reaction in the reduction zone is ensured by the reactor's own heating means, in particular by indirect contact with the hot charge to be treated. Once the reduction is complete, the catalyst reaches the proper reaction zone.

Also in the prior art, the regenerated and reduced catalyst is generally subjected to a sulfiding treatment before reaching the original reaction zone, during which all the metals of the catalyst are sulfided to a significant extent. The sulfidation reaction takes place at the top of the reactor, either in the same zone as the reduction takes place or in a zone just below the reduction zone. In the sulfidation zone, according to the prior art, operations are carried out at the temperatures required by the temperature at which the reduction takes place, ie between 480 and 600°C.

The sulfiding agent used is alternatively pure hydrogen sulfide or hydrogen sulfide diluted with hydrocarbon gas, or alternatively dimethyl difluoride diluted with hydrogen or other sulfur compounds such as alkyl sulfides or alkyl mercaptans, diluted with hydrogen. This is what I did. The pressure used will be that within the reforming reactor or aromatic hydrocarbon production reactor, and the duration of the sulfurization reaction will vary from a few minutes to several days depending on the operating conditions selected.

Conventional Example 1 FIG. 3 does not belong to the present invention, but illustrates one method in the prior art.

In FIG. 3, three reactors are used. The charge is led through conduit 1 , furnace 2 and flow path 3 to first reactor 29 . Effluent from first reactor 29 is removed by conduit 30 and sent through furnace 37 and conduit 38 to second reactor 42 . Second
Effluent from reactor 42 is removed by conduit 43 and sent through line 50 and conduit 51 to a third reactor 55. The effluent from the third reactor 55 is removed by conduit 56. Unused catalyst is introduced into the first reactor 29, for example via line 4, upon start-up of the unit. The regenerated catalyst is provided in a conduit or lift 19 as well as in a plurality of conduits 2.
7, 28 into the first reactor 29.
The catalyst passes through conduits 27 and 28 into contact zone 22. This process takes place in the form of a fluidized bed.

The catalyst is removed from the first reactor 29 by a plurality of conduits 31, 32 as well as a conduit 33 which takes the catalyst to a lift pot 34. This removal may be done periodically by any suitable gating system, or, even better, continuously without gating. The regulation of the flow rate of the catalyst is then ensured by classical means, at the level of the lift pot 34, by means of pure hydrogen injected by a conduit, not shown, or by the force of hydrogen generated within the unit. Ru.

The gas flow rate of the unit is adjusted to prevent a portion of the reaction effluent from being carried away with the catalyst particles. The catalyst is then transported from the lift pot 34 to the second reactor 42 by any known lifting device, herein referred to by the term "lift." The fluid in the lift 36 may be recycled hydrogen introduced through the conduit 35, i.e. hydrogen produced by the unit.

The catalyst transported into the lift 36 in this way,
Receptacle 39 is reached and from there a plurality of conduits 40, 4
1 to reach the second reactor 42. Here, the receiver 39 and the conduits 40, 41 may form part of a second reaction device 42 depending on the case. In other words, it may be provided within the second reaction device 42.

The catalyst passes through the second reactor 42 in the form of a fluidized bed and is removed from the second reactor 42 by a plurality of conduits 44 , 45 as for the first reactor 29 and by a lift-off conduit 46 . Reach pot 47. For example, a lift 49 receives a supply of recycled hydrogen or unit hydrogen coming through conduit 48.
The catalyst then reaches a receiver 52 and from there via a plurality of conduits 53, 54 to a third fluidized bed reactor 55. The catalyst is in the first and second reactors 2
9, 42, a plurality of conduits 57, 5
8 from the third reactor 55.

This spent catalyst reaches lift pot 60 by conduit 59. This spent catalyst is then conveyed to an "accumulator decanter" flask 7, for example by means of a lift 6 which is fed with recycled hydrogen which is fed by a conduit 61 into a lift pot 60. The spent catalyst reaches the regeneration zone 10 through the gate valve system 8 and conduits 5,9.

After catalyst regeneration is complete and the regenerated catalyst is purged to remove molecular oxygen (the various supply conduits required for regeneration and purging are conventional and are not shown in the diagram). ), this regenerated catalyst is sent to a receiving flask 15 through channels 11, 13 and a gate valve system 12. Among them,
Optionally, the regenerated catalyst is swept away by a stream of pure hydrogen directed through conduit 14 in order to maintain a mildly elevated pressure in receiving flask 15 relative to lift pot 17. The catalyst removed from flask 15 via conduit 16 is therefore:
The first reactor 29 is heated by pure hydrogen which reaches the lift pot 17 and is fed therefrom by the conduit 18.
Lift 1 towards the reduction zone 20 placed at the top of the
Carried to 9th.

The reduction zone 20 can optionally be used if the pure hydrogen in the lift 19 is not sufficient to undertake the reduction.
It receives the supply of hydrogen sent through the conduit 21.
The catalyst flows through the reduction zone 20 in the form of a fluidized bed. The catalyst is then removed from the reduction zone 20 by a plurality of conduits 27, 28, in which it also flows in the form of a fluidized bed of catalyst.

Gas containing sulfur compounds or in some cases
It is in the conduits or legs 27, 28 that the sulfidation of the catalyst takes place with pure hydrogen used as a carrier gas for the sulfur compounds. This sulfur-containing gas is transferred to conduit 2 through conduits 24, 25 and 26.
7,28. The gas turbulence in the conduits or legs 27, 28 is very strong, thus ensuring a smooth sulfurization reaction.

Since conduits 27 and 28 are generally filled with catalyst, sulfur-containing gas and an excess of hydrogen in conduits 18, 19, 21, it is necessary to remove the excess pure hydrogen by means of discharge conduit 23. The reduced and sulphurized regenerated catalyst then enters the actual contact zone 22 through conduits 27,28.

Problems with Conventional Example 1 In FIG. 3, reduction and sulfidation are performed at the head of the first reaction device 29, that is, at the upper part of the inside of this reaction device 29, so that the temperature of reduction and sulfidation is the temperature of the reaction device itself, that is, the temperature of the reaction device itself. Reforming temperature (480°C or higher) or aromatic hydrocarbon formation temperature (preferably 520°C or higher)
subject to restrictions. There is therefore no way in any case to cause the temperature in the upper part of the first reactor 29 to vary rapidly, since the reactor exhibits a very large thermal inertia.

Therefore, from this fact, it is impossible to accurately control the reduction temperature and the sulfidation temperature since they are practically equal to the temperature at which the reforming reaction or the aromatic hydrocarbon production reaction takes place. Therefore, in the method carried out according to FIG. 3, it is recognized that it is desirable to carry out the sulfurization reaction at a moderate temperature, for example in the range of 300 to 390°C, and there is room for improvement in this method. be.

Conventional Example 2 Recently, in Japanese Patent Laid-Open No. 53-90303, the arrangement shown in FIG. 4 was proposed, although it is not based on the present invention. According to this, the two reactions, reduction and sulfidation, are carried out separately on the one hand, and outside the reactor on the other hand.

In FIG. 4, three reactors are also used. The charge is led to the first reactor 29 via the conduit 1, the furnace 2 and the channels 3, 4. First reactor 2
Effluent from 9 is removed by conduit 30 and sent through furnace 37 and conduit 38 to second reactor 42 . The effluent from the second reactor 42 is transferred to the conduit 4
3 and sent through a furnace 50 and a conduit 51 to a third reactor 55. The final effluent is removed from the third reactor 55 by conduit 56.

Unused catalyst is introduced into the first reactor 29 during start-up of the unit by a conduit not shown in FIG. The regenerated catalyst enters the first reactor 29 via a conduit or lift 19 as well as a plurality of conduits 27,28. The catalyst is in the form of a fluidized bed in the conduits 27, 28 on the one hand and in the first
Proceed through the reactor 29.

The catalyst is placed in the fourth
Proceeding through the three reactors 29, 42, 55 shown. The catalyst is connected to conduits 31 and 32, conduit 33, lift and
It flows sequentially through pot 34 and lift 36. Fluid for lift 36 is admitted through conduit 35. The catalyst thus reaches and passes through the second reactor 42 through the plurality of conduits 40, 41;
It is taken out of this second reactor 42 by conduits 44, 45 and sent to the lift pot 4 through conduit 46.
Reach 7. By means of a lift 49 through which the carrier fluid is admitted through conduit 48, the catalyst reaches receiver 52 and passes through conduits 53, 54, third reactor 55 and conduits 57, 58 and then conduit 59. The spent catalyst thus removed from the third reactor 55 by conduit 59 reaches a lift pot 60 from where it is fed by the lift 6 with recycled hydrogen introduced through conduit 61. , sent to "Accumulator Decanter" flask 7.

The spent catalyst also reaches the regeneration zone 10 through the gate valve system 8 and conduit 9. After regenerating the catalyst and purging the regenerated catalyst to remove molecular oxygen, the regenerated catalyst is sent to reduction zone 20, just as in FIG. The various supply lines required for regeneration and purging are conventional and not shown.

The regenerated catalyst flows through channels 11, 13, gate valve system 12 and receiving flask 15;
Receiving flask 15 is optionally purged with a stream of pure hydrogen introduced through conduit 14.
The catalyst is removed from the receiving flask 15 by conduit 16 and reaches a lift pot 17 from where it is carried to lift 19 by pure hydrogen introduced by conduit 18. Thus the catalyst is in reduction zone 2
Reach 0.

The difference from FIG. 3 is that in FIG. 4, the reduction zone 20 is located above the first reactor 29, rather than at the top inside the first reactor 29. The reduction zone 20 may also be connected to the lift 19
If it is determined that there is not enough pure hydrogen to carry out this reduction, a supply of pure hydrogen is introduced via conduit 21. The reduction zone 20 is, for example,
It is heated by indirect contact with a portion of the charge via conduits 5,22. The split portion of the charge that serves to heat the reduction zone 20 is then generally routed directly to one of the two reactors 42,55.

The catalyst is then removed from the reduction zone 20 through a plurality of conduits 27,28. In these conduits or "legs" 27, 28, in other words outside the first reactor 29, the sulfurization of the catalyst takes place with the aid of sulfur compounds, which are optionally conveyed in pure hydrogen. This sulfur-containing gas is introduced into conduits 27, 28 through conduits 24, 25, 26. Excess hydrogen is removed via conduit 23. The catalyst then enters the first reactor 29.

Problems with Conventional Example 2 According to the method shown in FIG. 4, reduction can be carried out at a slightly more moderate temperature than in FIG. However, the ring temperature is still excessively high, generally above 530°C. because,
This is because the reforming reaction and the aromatic hydrocarbon production reaction generally require a temperature of at least 540° C., and the method shown in FIG. 4 is ultimately just a modification of the method shown in FIG. 3.

Due to the high temperature of the reduction reaction and the fact of the high temperature of the reaction zone, and because of the heat conductivity of the legs 27, 28, the scheme of Figure 4 makes it possible to obtain much more moderate temperatures than in Figure 3. I don't. In effect, therefore, the sulfiding temperature is as excessive as in FIG. 3 where it is forced to the temperature of the reactor.

Therefore, the system of FIG. 4 is not satisfactory because it has the same serious problems as the system of FIG. (a) First of all, each reaction zone exhibits extremely large thermal inertia, so that, for example, even if the upper part of the first reaction zone (numeral 20 in FIGS. 3 and 4) Even if located outside the first reactor 29, there is no way to rapidly vary the temperature of this section 20. In fact, in FIG. 4, since the reduction temperature and the sulfurization temperature are equal to the temperatures at which the reforming reaction and the aromatic hydrocarbon production reaction take place, it is impossible to properly adjust either the reduction temperature or the sulfurization temperature.

(b) Secondly, the fact of the thermal inertia of the upper part of the first reactor 29 or of the parts adjacent to this reactor results in that the sulfurization temperature is virtually always above the temperature at which reduction takes place, i.e. 480°C. .
However, in order for this sulfurization to be more effective, in other words, for sulfur to be more firmly fixed on the metal of the catalyst, it is desirable that the sulfurization temperature be 400° C. or lower. The ideal sulfiding temperature is 390℃
Or it would be below 380℃.

(c) Furthermore, the safety conditions for the systems shown in Figures 3 and 4 are still not sufficient. In fact, by purging the catalyst with nitrogen following regeneration of the catalyst, it is possible to remove all the oxygen gas acted upon during the course of the regeneration and thus avoid the risk of explosion in the reduction zone. However, if an explosion were to occur suddenly due to unspecified causes such as high pressure or accidental leakage, it would immediately propagate into the sulfidation zone and the reforming reaction zone or the aromatic hydrocarbon production reaction zone. This is because the reduction, sulfidation and reaction zones are very close to each other.

According to the present method according to the present invention, it is possible to prevent these problems. In this method, on the one hand, the reduction zone and the sulfidation zone are mutually distinguished;
On the other hand, both are located at a distinct distance from the first reactor.

SUMMARY OF THE INVENTION The present invention is a process for the reforming of hydrocarbons, i.e. for the production of aromatic hydrocarbons, in the temperature range from 480 to 600° C. and in the presence of a catalyst, comprising an initial charge consisting of hydrocarbons and hydrogen. Things,
The flow is conducted through at least two reaction zones arranged in series and each of the fluidized bed type, with the charge flowing through each reaction zone in turn and the catalyst flowing through each of them from above, also in the form of a fluidized bed. In a method in which the catalyst flows continuously to the bottom and sequentially passes through each reaction zone, and the catalyst is continuously taken out from the bottom of the last reaction zone through which the charge has passed and is sent into the regeneration zone, , in a hydrogen treatment zone separate from the reaction zone, in which the catalyst is treated with purified unit-derived hydrogen at a temperature range of 320 to 370°C; flowing in the form of a fluidized bed, the regenerated catalyst being treated with hydrogen before being fed afresh into the first reaction zone, passing continuously down through the first enclosure; The first enclosure is into which the sulfur compound is injected, and the regenerated hydrotreated catalyst is transferred from said first enclosure above the first reaction zone through which the charge has passed. and a catalyst is then continuously flowed from said second enclosure into a first reaction zone, said regenerated and hydrotreated catalyst. is caused by the force of the sulfur compound injected into said first enclosure during its continuous progress from the first enclosure to the first reaction zone.
A process is characterized in that the sulfidation is carried out at a temperature in the range 220-280°C and 70-130°C lower than the temperature at which the hydrotreatment of the regenerated catalyst is carried out.

In the present invention, (the treatment with hydrogen is
370°C, preferably around 350°C, sulfurization is performed at a temperature of 70 to 130°C lower than the hydrogen treatment temperature, and this temperature is 200 to 280°C.
between 220 and 280°C, more preferably close to about 250°C),
The following became possible. That is, for example,
Provided that the hydrogen originating from the unit has undergone a relatively simple purification of washing this hydrogen with the reformate effluent in the plate column, this hydrogen originating from the purification unit can be used for hydrogen treatment and for hydrogen production. If there is a lift in the apparatus (to convey the treated catalyst to the top of the reactor), it can be used as a carrier gas during the entire operating period of the unit. Hydrogen from the unit purified in this manner will be referred to as "purified unit-derived hydrogen" in this specification. As a result of the relatively low temperatures of the hydrogen treatment and sulfurization reactions, such hydrogen derived from units and purified to some extent by simple means has a high concentration of hydrogen in it, despite the impurities it still contains after this simple purification. It does not cause parasitic explosions caused by side reactions called hydrocracking of hydrocarbons. In fact, this side reaction cannot occur at the relatively low temperatures used in hydrotreating and sulfurization.

On the other hand, in the methods shown in FIGS. 3 and 4, the hydrogen treatment of the catalyst and its sulfidation are carried out at relatively high temperatures.
Since this is generally carried out at temperatures close to those used in the reactor itself, very expensive methods such as purification of pure hydrogen or, in some cases, passing the hydrogen over molecular sieves or by low temperature chemical methods, are required. There was an absolute need for recycled hydrogen, which required prior rigorous purification by such physicochemical methods.

In a preferred embodiment of the present invention, the following operations are performed.

(1) The hydrogen treatment is carried out by the power of purified unit-derived hydrogen, which flows counter-currently through the catalyst through the aforementioned hydrotreatment zone, so that the continuous hydrocarbon conversion process according to the present invention proceeds. .

(2) Spent catalyst removed from the bottom of the last reaction zone through which the charge passes, before or during the transition of the catalyst to the regeneration zone, absorbs at least a portion of the hydrogen derived from the purified unit. It is first purified by scavenging air.

(3) A first enclosure into which a sulfur compound is injected on the one hand and a hydrogen stream on the other hand, which hydrogen stream carries the regenerated and hydrotreated catalyst into a second enclosure. The hydrogen treatment is carried out by the power of purified unit-derived hydrogen, which flows against the progress of the catalyst through the hydrotreatment zone. It is something that progresses.

(4) The spent catalyst removed from the lower part of the last reaction zone through which the charge passes, before or during the transition of the catalyst to the regeneration zone, is driven by at least a portion of the hydrogen derived from the purified unit. It is first purified by scavenging.

The object of the present invention is a process in which the catalyst, after being regenerated, undergoes treatment with hydrogen and sulfidation in two distinct zones clearly separated from the reaction zone. Thus, according to the present method, hydrogen treatment and sulfurization can be carried out at moderately ideal temperatures, which are significantly lower than those used in the prior art. In the prior art, the hydrotreating and sulfiding zones are located in close proximity to the reaction zone, so that the hydrotreating and sulfiding temperatures are effectively limited to the reaction zone temperature.

The present invention relates to a method for reforming hydrocarbons. The present invention also describes naphthenic hydrocarbons starting from unsaturated or unsaturated gasolines (e.g. pyrolysis gasolines, especially steam cracking gasolines, or catalytically reformed gasolines) or which can be converted to aromatic hydrocarbons by dehydrogenation. Aromatic hydrocarbons starting from hydrocarbons, such as benzene,
It also relates to the production of toluene and ortho, meta or bulk xylenes.

In this method, at least two reactors or reaction zones, preferably three to four reactors or reaction zones, are used to carry out the reforming reaction, that is, the reaction for producing aromatic hydrocarbons. Each contains a fluidized bed of catalyst.

The charge can be axial or radial (i.e. from the center to the periphery or from the periphery to the center)
flows through each reactor or reaction zone in sequence according to the flow. The reaction zones may be arranged in series, e.g. side by side or stacked one on top of the other, such that the charge flows through each of these reaction zones in turn with intermediate heating between each zone. , has been placed.

The new catalyst is placed at the top of the first reaction zone which receives the new charge. The catalyst then flows continuously from the top to the bottom of this zone, from which it is continuously removed and conveyed by any suitable method (especially lift) to the top of the next reaction zone, It similarly flows therein from the top to the bottom, and so on until the last reaction zone, where it is continuously removed and then sent to the regeneration zone.

It is desirable to arrange the reaction zones side by side.

The flow of catalyst from the lower part of one reaction zone to the upper part of another reaction zone, and the flow of catalyst from the lower part of the last reaction zone to the regeneration zone, and in some cases, the flow of catalyst from the lower part of the regeneration zone to the first reaction zone. The upper distribution of the strip is effected by means of any known lifting and unloading device, designated herein by the word "lift". The lift fluid used to deliver the catalyst may be any suitable gas, such as nitrogen, pure or purified hydrogen, or hydrogen produced within the system.

The solids transferred from reaction zone to reaction zone and to regeneration zone may be, for example, particulate catalyst. The catalyst may, for example, be spherical with a diameter generally comprised between 1 and 3 mm, preferably between 1.5 and 2 mm. However, these numerical values are not limited. Generally the specific weight of the catalyst is between 0.4 and 1, preferably between 0.5 and 0.9, in particular between 0.55 and 0.8. However, these numerical values are not limited.

The reactions to which the method according to the invention is preferably applied are:
Although listed at the beginning of this specification, they can be clearly divided into the following two groups.
(1) One of them is the rehoming reaction. The general conditions for the catalytic reforming reaction are as follows. That is, the average temperature in each reaction zone is in the range of about 480 to 600 °C or 530 to 600 °C, the pressure is in the range of about 5 to 20 Kg/cm ² , and the speed is 0.5 to 1 volume of catalyst. The recirculation rate ranges from 1 to 10 moles of hydrogen per mole of charge.

Specific examples of rehoming reactions include the following.

Charge: Naphtha distilled in the range of about 60 to 220°C, especially direct distilled naphtha.

Catalyst: The catalyst comprises at least one metal of the platinum group, reduced to one of the noble metals such as platinum, palladium, iridium, ruthenium, osmium, supported on a support of alumina or equivalent compounds. (e.g., platinum-alumina-halogen or platinum-iridium-alumina-halogen), the content of noble metals relative to the catalyst
The content of halogen, preferably chlorine or fluorine, is 0.1 to 2% by weight, preferably 0.1 to 10%.
Alumina-halogen combination with other carriers,
For example, silica-alumina can be used instead. The catalyst may also include at least one metal cocatalyst selected from each group on the periodic table of elements.

(2) The other one is the production reaction of aromatic hydrocarbons from saturated or unsaturated gasoline.

If the feed is unsaturated and contains diolefins and monoolefins upon reduction, they must first be removed by selective or total hydrogenation. Next, when the charge contains olefins,
If necessary, the charge, which has been freed of all its olefins and to a considerable extent by hydrogenation, is mixed with an acidic support and at least one metal, such as one noble group metal (platinum group metal), in each reaction zone. ) and/or at least one metal promoter appropriately selected from the periodic table of elements and hydrogen at about 500 to 600°C or
At a temperature in the range of 520 to 620°C and a pressure in the range of 1 to 60 Kg/cm ² , the volumetric flow rate of the liquid charge per hour is approximately 0.1 to 10 times the volume of the catalyst.
The aromatic hydrocarbon production reaction is carried out at a hydrogen/hydrocarbon (molar ratio) of approximately 0.5 to 20.

Regeneration of the original catalyst can be carried out using all known methods. Preferably,
The catalyst is (a) combusted with the aid of a gas containing molecular oxygen.

(b) Oxychlorination using a gas containing molecular oxygen and simultaneously using a halogen or a halogen compound, such as hydrohalic acid or an alkyl halide.

(c) Final treatment with a gas containing molecular oxygen.

These three treatments may be carried out sequentially, either in a single fixed bed zone or within the confines of a fluidized bed, with the catalyst successively entering distinct zones in which these three steps of regeneration take place. .

Regeneration involves purging, for example with nitrogen, to remove any traces of residual oxygen gas from the catalyst.

Functions and Effects of the Invention Since the method for continuous conversion of hydrocarbons according to the present invention is configured as described above, the following effects are achieved.

First, the method of the present invention allows hydrogen treatment and sulfurization to be carried out at moderately ideal temperatures, which are significantly lower than those used in the prior art.

More specifically, in these two zones, hydrotreating and sulfiding, thermal inertia no longer exists and the temperature in the hydrotreating zone (e.g. by diversion of a portion of the charge) and the temperature in the sulfiding zone is controlled. It can be easily and independently adjusted to the desired value. In particular, the hydrogen treatment temperature can be adjusted to an optimum temperature, generally in the range of 320-370°C. Similarly, in the prior art the sulfiding zone was located between two high temperature zones, namely the reduction zone and the reactor, making it impossible to reduce the temperature of the sulfiding zone, whereas in the present invention In the method, the sulfurization and hydrogen treatment temperatures range from 70 to
It has become particularly easy to perform at temperatures below 220-280°C, which is 130°C lower.

According to the present invention, hydrogen derived from the unit and purified to some extent by simple means can be used as hydrogen for the hydrogen treatment of the catalyst. And, because of the relatively low temperatures of the hydrogen treatment and sulfurization reactions described above, this purified unit-derived hydrogen, despite the impurities it still contains even after the simple purification described above,
It does not cause parasitic explosions caused by the side reaction of hydrocracking of hydrocarbons in the hydrogen.

Additionally, the hydrogen treatment zone and sulfidation zone are located at a distance from the reaction zone, so even if an explosion were to occur in the hydrogen treatment zone, this would surely prevent the explosion from propagating to the reaction zone and causing a major accident. be able to.

More specifically, in the present process according to the invention, even if, despite the purging following the original regeneration of the catalyst, traces of oxygen are still present in the regenerated catalyst and it happens that the hydrogen treatment Even if an explosion were to occur in the zone, this explosion would not spread into the first reactor, which is now completely separate from the hydrotreatment zone.

EXAMPLE In the present method illustrated below with reference to FIGS. 1 and 2, purified unit-derived hydrogen can be used. The purified unit-derived hydrogen may contain up to 10% by volume, preferably up to 4%, of various lower hydrocarbons such as ethane and propane.

Methane is not considered an impurity up to an amount equal to the volume of hydrogen. It is noted that in extreme cases the hydrogen stream may contain 50% methane by volume.

Therefore, the unit-derived hydrogen is shown in Figures 1 and 2.
In the arrangement shown in the figure, the regenerated catalyst can be treated with hydrogen not only temporarily when other hydrogen sources are in short supply, but also as a hydrogen source throughout the duration of simple post-purification reforming reactions and aromatic hydrocarbon production reactions. Also, when the regeneration zone is placed to the side of the first reaction zone, the lift required to raise again the catalyst that has been regenerated above the first reactor and treated with hydrogen. It can also be used for propellant fluids.

In Figures 1 and 2, three reactors are used. In each of these two figures, the charge passes through conduit 1, furnace 2, flow path 3 to first reactor 2.
introduced in 9. The effluent from the first reactor 29 is taken off by conduit 30 and is taken from the furnace 37 and conduit 3
8 to the second reactor 42. Effluent from second reactor 42 is removed by conduit 43 and sent through furnace 50 and conduit 51 to third reactor 55. Effluent from the third reactor is removed by conduit 56.

Unused catalyst can be removed during start-up of the unit, for example by conduit 4 in FIG.
It is introduced into the first reactor 29 by a conduit, which is not shown in the figure. The catalyst coming from the regeneration zone 10 enters the first reactor 29 via conduits 27,28. The catalyst proceeds in the form of a fluidized bed.

The catalyst is removed from the first reactor 29 by a plurality of conduits 31, 32 as well as a conduit 33 which takes the catalyst to a lift pot 34. This extraction is done continuously (gate valve method is not essential). The catalyst flow rate can be adjusted using the lift pot 34.
, by classical means with pure hydrogen or unit-derived hydrogen injected by conduits not shown in FIGS. 1 and 2.

The gas flow rate of the unit is adjusted to prevent a portion of the reaction effluent from being carried away with the catalyst particles. The catalyst is then transported from the lift pot 34 to the second reactor 42 by any known lifting device, herein referred to by the term "lift." The fluid in the lift 36 may be recycled hydrogen introduced through the conduit 35, i.e. hydrogen produced by the unit.

The catalyst thus conveyed into the lift 36 reaches a receiver 39 from where it passes through a plurality of conduits 4
0.41 to reach the second reactor 42.
Here, the receiver 39 and the conduits 40, 41 may form part of a second reaction device 42, depending on the case. In other words, these are the second reactor 42
Sometimes it is installed inside.

The catalyst passes through the second reactor 42 in the form of a fluidized bed and is removed from the second reactor 42 by a plurality of conduits 44 , 45 as for the first reactor 29 and by a lift-off conduit 46 . Reach pot 47. For example, a lift 49 receives a supply of recycled hydrogen or unit hydrogen coming through conduit 48.
The catalyst then reaches a receiver 52 and from there via a plurality of conduits 53, 54 to a third fluidized bed reactor 55.

Catalyst is removed from the third reactor 55 by a plurality of conduits 57, 58, as well as for the first and second reactors 29, 42. This spent catalyst reaches lift pot 60 by conduit 59. This spent catalyst is then transferred to an "accumulator decanter" flask 7, for example by means of a lift 6 which is fed with recycled hydrogen which is fed by a conduit 61 into a lift pot 60. The spent catalyst reaches the regeneration zone 10 through the gate valve system 8 and the conduits 21,9.

After catalyst regeneration is complete and the regenerated catalyst is purged to remove molecular oxygen (the various supply conduits required for regeneration and purging are conventional and are not shown in the diagram). ), this regenerated catalyst is passed periodically or continuously to the upper part of the enclosure 15 through the channels 11, 13 and the gate valve system 12. Pure hydrogen is introduced into it through conduit 14.

The catalyst passes in the form of a fluidized bed into the lower part or lower zone 26 of the enclosure 15. In the lower band 26, the conduit 14
Hydrogen treatment of the regenerated catalyst is carried out using hydrogen admitted through. The catalyst travels through the lower zone 26 in the form of a fluidized bed.

In FIG. 1, the regenerated and hydrogen-treated catalyst is continuously removed from enclosure 15 by conduit 16 to lift pot 17 and from there through conduit 18 to lift 19. The purified unit-derived hydrogen introduced into the reactor is carried by the first reactor 29 towards the receiving flask 20 located above. The catalyst is then
A plurality of conduits or "legs" 2 from the receiving flask 20
7, 28, it flows continuously in the form of a fluidized bed towards a first reactor 29.

The sulfidation carried out after hydrogenation of the regenerated catalyst is
Partly in the lift pot 17 and possibly partly in the lift 19, the receiving flask 2
0 as well as legs 27 and 28. The sulfur compounds and optionally hydrogen (preferably purified unit derived hydrogen) used as a carrier gas for the sulfur compounds are admitted into the lift pot 17 through conduit 24.

The progress of the catalyst is carried out continuously in the enclosure 15, in the lift pot 17 and in the receiving flask 20, in the lift 9 and in the delivery tube of this catalyst, in order to maintain the correct hydrogen treatment and sulfidation temperatures. Ensure regulation and avoid subjecting the catalyst to sudden temperature fluctuations.

Excess hydrogen generated during the course of hydrogen treatment can be removed through discharge tube 22.

In FIG. 2, the regenerated and hydrotreated catalyst is shown in conduit 4 and possibly gate valve 1.
6 from the enclosure 15 (located above the first reactor 29) and continuously into the receiving flask 17 located above the first reactor 29. Go down. From this receiving flask 17 the sulfurization reaction can take off; optionally, the sulfur compounds carried by the hydrogen stream (hydrogen from purified units) are admitted via conduit 24. The catalyst is now in conduit 1
8, 5 as well as a continuous descent into the accumulator flask 20, optionally via a gate valve 19. The catalyst then flows continuously from the flask 20 into the first reactor 29 in the form of a fluidized bed through a plurality of conduits or "legs" 27,28.

The catalyst flows in a fluidized bed from the enclosure 15 to the first reactor 29 (if appropriate, the gate valve used is open or removed). This is to ensure that the temperature of the hydrogen treatment and sulfidation is properly controlled and that the catalyst is not subjected to sudden temperature fluctuations.

Excess hydrogen generated during the course of hydrogen treatment can be removed through discharge tube 22.

In FIG. 2, the sulfidation that takes place after the hydrotreatment of the regenerated catalyst takes place partly in the receiving flask 17, partly in the conduits 18, 5 and possibly partly in the flask 20. and legs 27, 28
It is also done inside.

1 and 2, the purified unit-derived hydrogen is heated by at least a portion of the charge or reaction effluent or by a separate furnace (in FIG. 1 through conduit 14). A furnace 5 for heating the hydrogen is shown).

In FIGS. 1 and 2, purified unit-derived hydrogen enters the enclosure 15 through conduit 14 located in the upper part of the enclosure 15, while excess hydrogen enters the lower part of the enclosure 51. It is taken out through the discharge tube 22 located at. The purified hydrogen derived from the unit is placed in the surrounding area 15.
Advantageously, excess hydrogen is taken off by means of a discharge pipe 25 at the top of the enclosure 15 (conduits 14, 22 are omitted in this case).

Operating in this way with a flow of hydrogen flowing back to the catalyst to be treated ensures a better contact between the hydrogen and the particles of the catalyst (particularly in the lower zone 26, which is narrower than the upper part of the enclosure 15); Operating in this manner uses less hydrogen than operating upstream. Moreover, the counterflow method allows the flow rate of the catalyst inside the enclosure 15 to be more easily adjusted by adjusting the flow rate of hydrogen.

Note in FIGS. 1 and 2 that the catalyst removed from the third reactor 55 via conduit 59 contains traces of hydrocarbons and traces of sulfur or sulfur compounds. These various traces are undesirable within the regeneration zone 10 (hydrocarbons increase burnup, sulfur destroys the catalyst). The spent catalyst stored in flask 7 is transferred to hydrogen (purified unit-derived hydrogen) in channel 14.
It has been found to be advantageous to purify by scavenging with at least some force. This scavenging can take place during the transfer of catalyst from flask 7 to regeneration zone 10 before the catalyst passes from flask 7 to regeneration zone 10 .

In FIGS. 1 and 2 according to the present invention,
The regenerated catalyst is subjected to reduction or treatment with hydrogen in area 15 of these figures or in the form of a fixed bed.

Preferably, the enclosure 15 is of the fluidized bed type in order to ensure better continuity of the catalyst progress.

In this case, in order not to crowd the drawing, it is necessary to replace periodic withdrawals from the regeneration zone 10 with a continuous feed into the reduction or hydrotreating zone, for example when regeneration is carried out in a fixed bed. Additional gate valves or vessels required for conversion are not shown.

Similarly, if the reduction or treatment with hydrogen of the regenerated catalyst is carried out in a fixed bed in enclosure 15 of the figure, the necessary ancillary equipment is required to allow the catalyst to proceed continuously from the outlet of enclosure 15 towards the sulphidation zone. is not shown either.

[Brief explanation of drawings]

1 and 2 are pipe system diagrams showing an embodiment of the present invention, and FIGS. 3 and 4 are pipe system diagrams showing the prior art.

Claims (1)

[Claims] 1. A process for reforming hydrocarbons, i.e. for the production of aromatic hydrocarbons, in the temperature range from 480 to 600°C and in the presence of a catalyst, comprising an initial charge consisting of hydrocarbons and hydrogen. are passed through at least two reaction zones arranged in series and each of the fluidized bed type, the charge flowing through each reaction zone in turn and the catalyst also flowing through each of them in the form of a fluidized bed. A method in which the catalyst flows continuously from the top to the bottom and passes through each reaction zone in turn, and the catalyst is continuously taken out from the bottom of the last reaction zone through which the charge has passed and is sent into the regeneration zone. The catalyst passes down through a hydrotreating zone separate from the reaction zone, in which it is treated with purified unit-derived hydrogen at a temperature range of 320 to 370°C; flowing in the form of a fluidized bed through the first reaction zone, where the regenerated catalyst is treated with hydrogen before being fed anew into the first reaction zone, and flowing continuously down through the first enclosure; , the first enclosure is into which sulfur compounds are injected, and the regenerated and hydrotreated catalyst is transferred from said first enclosure above the first reaction zone through which the charge has passed. flowing continuously into a second enclosure located at
Catalyst then flows continuously from the second enclosure into the first reaction zone, and the regenerated and hydrotreated catalyst continues to flow from the first enclosure to the first reaction zone. On the way, with the force of the sulfur compounds injected into the first enclosure, 220
A process characterized in that it undergoes sulfidation carried out at a temperature in the range from 280°C to 70° to 130°C below the temperature at which the hydrotreatment of the regenerated catalyst is carried out. 2. The method according to claim 1, wherein the hydrogen treatment is carried out by the power of purified unit-derived hydrogen, and the hydrogen proceeds in the hydrogen treatment zone countercurrent to the progress of the catalyst. 3. Before or during the transfer of the catalyst to the regeneration zone, the spent catalyst removed from the bottom of the last reaction zone through which the charge passes is subjected to force scavenging of at least a portion of the purified unit-derived hydrogen. A method according to claim 1, wherein the method is first purified by: 4 The first enclosure is into which sulfur compounds are injected on the one hand and a hydrogen stream is injected on the other hand, which hydrogen stream continues the regenerated and hydrotreated catalyst into the second enclosure. Furthermore, the hydrogen treatment is carried out using the power of purified unit-derived hydrogen.
The hydrogen proceeds in the hydrogen treatment zone countercurrently to the progress of the catalyst.
The method described in section. 5. Before or during the transfer of the catalyst to the regeneration zone, the spent catalyst removed from the lower part of the last reaction zone through which the charge passes is subjected to force scavenging of at least a portion of the purified unit-derived hydrogen. 5. A method according to claim 4, wherein the method is first purified by: