JPS6039111B2 - Catalytic conversion method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a multi-stage reaction system in which {i- a reactant stream flows continuously through a plurality of reaction zones and 'ii} catalyst particles are movable within each reaction zone as a gravity flow. The present invention relates to an improved method for catalytic conversion of hydrocarbon-containing reactant streams in a plant.

In particular, the method according to the invention is a gas phase reaction in which the conversion reaction is primarily endothermic and in which the hydrocarbon-containing reactant stream flows essentially radially in cocurrent relation to the direction of downward movement of the catalyst particles. Suitable for use in systems. A wide variety of multi-stage reaction systems are utilized throughout the petroleum and petrochemical industries to carry out many types of reactions, particularly hydrocarbon conversion reactions.

Multistage reaction systems generally take one of two configurations: {1) parallel type with intermediate heating between the reaction zones, where the reactant streams or mixtures are transferred from one zone to another; There are two types: one in which the catalyst flows continuously into the chamber, and the other in which the catalyst is of a stacked type, in which a single or more reaction chambers have a plurality of catalyst contact stages.

As applied to petroleum refining, such reactor systems include reactions that are effective for catalytic refining, alkylation, dehydrogenation of ethylbenzene for styrene production, and other dehydrogenation methods. It is employed to perform many hydrocarbon conversion reactions. The present invention is characterized in that the conversion reaction is carried out in the gas phase, the catalyst particles are movable as a gravity flow, and the reaction systems are present in a parallel arrangement or two.
A reaction system in which the above catalyst contacting zones are stacked or one or more other reaction zones are arranged in parallel to the stacked reaction zones. It is specifically intended for use in Since catalyst particles moving through a reaction system due to gravity flow naturally move in a downward direction, the method of the present invention takes catalyst particles from the bottom of one reaction zone and transfers them to the top of the next reaction zone. Including introducing new or regenerated catalyst particles.

Furthermore, the method of the present invention is characterized in that the catalyst is arranged as an annular bed;
It is also intended to be applied to reaction systems in which the reactant flow (continuous from one reaction zone to another) flows perpendicularly to the movement of the catalyst particles, ie radially. In summary, a radial flow reaction system consists of a reaction chamber containing a coaxially disposed catalyst retaining screen and a perforated central tube, the screen having an apparent internal cross section smaller than the reaction chamber. The central tube has an apparent internal cross-sectional area that is smaller than the catalyst retaining screen. The reactant stream is introduced in the gas phase into an annular space formed between the inner wall of the reaction chamber and the outer surface of the catalyst retaining screen. The catalyst retaining screen together with the perforated central tube forms an annular catalyst retaining band. The gas phase reactant stream flows laterally and radially through the screen and catalyst retention band into the central tube and exits the reaction chamber. The annular configuration of the various reaction zone elements may be of any suitable shape, for example triangular, square, rectangular or diamond-shaped, and from many design, construction and technical standpoints elements of substantially circular cross-section are preferred. It is profitable to use An example of a multi-stacked reaction zone system to which the present invention is particularly applicable is U.S. Pat.
Seen in No. 36.

The transfer of catalyst particles by gravity flow from one reaction zone to another, as well as the introduction of fresh catalyst and removal of spent catalyst, is accomplished by utilizing a plurality of catalyst transfer tubes.

Experience with such systems as well as systems with parallel reaction zones has shown that high velocity gas phase flow through the annular catalyst retention zone causes catalyst particles to accumulate in the vicinity of the perforated central tube. There is. Therefore, stagnation in the catalytic region is observed,
Gravity flow causes the catalyst to lose its morphology. A primary object of the present invention is to prevent or reduce stagnant catalyst zones in hydrocarbon conversion systems in which catalyst particles are movable by gravity flow.

It is also a natural object of the present invention to provide a multi-stage stack in which the catalyst particles in each reaction zone are movable by gravity flow, the catalyst particles flowing by gravity flow from one zone to the next successive reaction zone. An object of the present invention is to provide an improved process for use in type reactor systems. Another object obtained by utilizing the process of the present invention is the improvement of substantially endothermic hydrocarbon conversion systems carried out in the gas phase in which the catalyst particles are movable downward by gravity flow.

The invention thus provides, in one embodiment thereof, that a heated hydrocarbon feedstock and hydrogen flow sequentially through a plurality of catalytic reaction zones, and that the reaction product effluent flows between each successive reaction zone. In a multi-stage catalytic conversion process in which catalyst particles are heated and catalyst particles are movable by gravity flow within each reaction zone;
The first portion was then maintained at hydrocarbon conversion conditions. introducing this second portion into a second reaction zone maintained under hydrocarbon conversion conditions by restricting the flow of said heated feedstock and said second portion of hydrogen; 'c} restricting the flow of the effluent from said first reaction zone and mixing this flow with the effluent from said second reaction zone; {d} the obtained heating the mixture and introducing it into a third reaction zone maintained at hydrocarbon conversion conditions;'e} separating the effluent from the last reaction zone in the system to form a normally liquid product; (ii) a hydrogen-enriched gas phase and recycling at least a portion of said gas phase to said first reaction zone;
f} at least periodically removing catalyst particles from the last reaction zone in the system; and) introducing fresh or regenerated catalyst particles at least periodically into the first reaction zone in the system. A process for the catalytic conversion of said hydrocarbon feedstock, consisting of successive stages.

This embodiment may be further characterized in that the flow of effluent from the third reaction zone is restricted prior to being introduced into the fourth reaction zone.

More particularly, the present invention provides the steps of: [a] heating a mixture of a hydrocarbon feedstock and hydrogen; and then transferring a first portion of the heated mixture to a first catalytic reaction zone in which catalyst particles are movable by gravity flow. Introduction stage; {b}
restricting the flow of a second portion of the heated mixture and introducing this second portion into a second catalytic reaction zone in which catalyst particles are movable by gravity flow; {c- from said first catalytic reaction zone; restricting the flow of the effluent of and mixing this flow with the effluent from said second reaction zone:'d} heating the resulting effluent mixture so that the catalyst particles Step of introducing into the third catalytic reaction zone movable by the flow;'e}
restricting and heating the flow of the effluent from said third catalytic reaction zone and introducing said effluent into a fourth catalytic reaction zone in which catalyst particles are movable by gravity flow; The effluent is separated to provide (i) a normally liquid product stream and (ii) a hydrogen-enriched gas phase, with at least a portion of the gas phase being recycled to the hydrocarbon feedstock. (g) removing catalyst particles from said fourth catalytic reaction zone at least periodically; and a) introducing fresh or regenerated catalyst particles into said first catalytic reaction zone at least periodically. step.

The present invention relates to a multi-stage hydrocarbon catalytic reforming process consisting of successive stages.

This embodiment is such that the four reaction zones are arranged in a vertical stack with a common vertical axis and the catalyst particles are
It may be further characterized by being movable by gravity flow from one reaction zone to the next successive reaction zone.

These objectives and embodiments, as well as others, will become apparent from the following more detailed description of the hydrocarbon conversion process of the present invention.

In another such embodiment, by restricting the flow of each effluent, about 1. Yusi or about 10. A pressure drop in the blood si range is further applied to the reactor system. Many types of hydrocarbon conversion processes utilize multistage reactor systems, either parallel or vertically stacked, or stacked and one or more separate reaction zones in parallel. It is one of those that are roughly put together in a lined up form.

The invention is applicable to many conversion reactions and processes;
In these reactor systems, catalyst particles may be moved by gravity flow, but the present invention will be described below in connection with the well-known endothermic catalytic reforming process. Historically, catalytic reforming processes were carried out in a non-regenerative, fixed bed format consisting of multiple reaction zones arranged side by side.

When the catalyst complex becomes deactivated to the extent that continuous operation is no longer economically acceptable, the entire system is shut down and the catalyst is regenerated in situ. In recent years, "swinging bed" versions have been used that use extra reactors to replace reactors that are shut down for regeneration. . More recently, multistage reactor systems have been provided, in which catalyst particles flow under the influence of gravity through each reaction zone. In the "stacked" version, the catalyst particles flow downward from one catalyst retention zone to another and finally are transferred to the appropriate regeneration zone.
This regeneration zone is also preferably operated in the form of a moving bed below the catalyst particles. In practice, the flow of catalyst particles may be carried out continuously, or at frequent intervals, or even at long intervals, and the displacement is the amount of catalyst removed from the last of a series of reaction zones. The transfer from one area to another takes place in a manner coordinated by the. US Pat. No. 3,470,099 discloses a multi-stage parallel reaction system with intermediate heating of the reactant streams flowing successively through each reaction zone. Catalyst particles taken out from each reaction zone are appropriately transported to a regenerator. This type of system can be modified to a certain extent, such that the catalyst particles removed from a given reaction zone are sent to the next successive reaction zone, and the catalyst particles removed from the last reaction zone are transferred to the next successive reaction zone. It may also be sent to a playback device as appropriate. A stacked reaction zone configuration is disclosed in U.S. Pat. No. 3,647,688, which is a two-stage system with an integrated reactor that receives the catalyst removed from the bottom or last reaction zone. It is equipped with a playback device. U.S. Pat. No. 3,725,248 discloses a multi-stage system arranged in parallel, in which flowing catalyst particles under the action of gravity are transferred from the bottom of one reaction zone to the top of the next successive reaction zone. The catalyst particles taken out from the last reaction zone are appropriately sent to a regenerator.

The general details of the three reaction zone stacked system are detailed in U.S. Pat. No. 3,706,536, which discloses one form of a multi-stage system to which the present invention is applicable. There is.

As commonly practiced in catalytic reformers,
Each successive reaction zone accommodates a large volume of catalyst due to the large cross-sectional area of the annular catalyst holding region. We believe that the above description fairly accurately describes the state of the art for multistage conversion systems in which catalyst particles are movable through each reaction zone by gravity flow.

Of particular note, there is no recognition of the presence of stagnant catalyst when catalyst particles are unevenly distributed towards the perforated central tube due to the gas phase flowing laterally/radially across the annular catalyst bed. That's true. Similarly, the knowledge about restricting the reaction zone effluent flow or dividing the reactant flow to the first two reaction zones and restricting the reactant flow to the second reaction zone is I can't see it. US Pat. No. 3,864,240 discloses the integration of a reaction system with gravity flow catalyst particles and a fixed bed system.

As disclosed in that patent, one benefit lies in the modification of the conventional three reaction zone fixed bed system into an integrated system. It has been suggested to provide a second compressor to provide a split stream of hydrogen-rich recycle gas. The purpose of this additional compressor is to provide the necessary hydrogen recirculation to the moving bed section of the system, whereas the original compressor provides hydrogen recirculation to the multiple fixed bed reaction zones. This is what the cycle does. Therefore, such a moving bed reaction zone must contain all gas phase materials within the system, including recycled hydrogen from its own compressor and all effluent from the final fixed bed reaction zone. Must be. Also, this patent does not teach anything about the problems caused by regions of catalyst stagnation found in reaction zones with catalyst particles that are movable by gravity flow. The method according to the invention is suitable for use in hydrocarbon conversion systems which are multi-stage processing systems in which the catalyst particles can be moved through each reaction zone by gravity flow.

The present invention is primarily intended for use in reactor systems where the primary reaction is endothermic and the reaction takes place in the gas phase. It should be noted that, although the following explanation is particularly about the catalytic reforming method for naphtha boiling point range crab fraction, the present invention is not intended to be limited thereto. Catalytic reforming, like many other processes, has gone through several stages of development, currently consisting of systems in which the catalyst bed forms a descending column in one or more reaction vessels. It has become. Typically, the apparent diameter is between 0.8 and 4. The substantially spherical morphology of the catalyst is utilized to avoid bridging or interfering with the descent of one or more of the descending catalyst columns found throughout the system. In such a multistage system, as an example, the reaction chamber is vertically cumulus and a plurality of relatively small diameter conduits, typically about 6 to 1 needle, are used to separate one reaction zone. From there, the catalyst particles are transferred to the next lower reaction zone (by gravity flow), and finally the catalyst particles are taken out from the last reaction zone.

These catalyst particles are then sent to the top of the catalyst regenerator, which acts as a descending column of catalyst particles; the regenerated catalyst particles are then sent to the top of the upper reaction zone of the stacked reaction zone. In order to promote and enhance gravity flow within each reaction vessel and even from one zone to another, it is of particular importance that the catalyst particles have a relatively small apparent diameter.
Preferably, it has an apparent diameter of about 4.0 or less. In a conversion system in which gravity flow is observed in each reaction zone arranged in parallel, catalyst particles may be transferred from the bottom of one zone to the top of the next, or even in the last reaction zone. For transferring catalyst particles from the castle to the top of the regenerator, a catalyst transfer vessel of the form shown, for example, in US Pat. No. 3,839,197 is used. Catalytic reforming of naphtha boiling point range hydrocarbons carried out in the gas phase ranges from 371°C to
Conversion conditions are carried out including catalyst bed temperatures in the range of 5490C.

Other conditions include a pressure of 4.4 to 6 atm, a liquid hourly space velocity (defined as the volume of new feedstock per hour per unit volume of total catalyst particles) of 0.2 to 10.0; The hydrogenated hydrocarbon molar ratio is generally 0.5:1.0 to 10
．． It is in the range of 0:1.0. There are many benefits to continuous regeneration reforming systems when compared to traditional fixed bed systems. for example,
Relatively low pressure of 4.4-14.6 atm 510-5
Efficient operation is possible even at inlet catalyst bed temperatures as high as 43 oo. Catalytic reforming methods include dehydrogenation of naphtha to aromatics, dehydrocyclization of paraffins to aromatics, hydrogenolysis of long chain paraffins to normally liquid substances with low boiling points, and paraffins. There is isomerization, etc.

These reactions are endothermic in their overall result (i.e. overall result) and involve a porous material such as alumina and one or more side group noble metals bonded to a halogen (e.g. chlorine and/or fluorine). (eg, platinum, iridium, rhodium, palladium). Relatively recent research has shown that more beneficial results can be obtained with the combined use of catalytic modifiers.
The catalyst modifier is selected from the group consisting of cobalt, nickel, potassium, germanium, tin, rhenium, vanadium and mixtures thereof. Regardless of the catalyst composition used, the advantages over conventional fixed bed systems are due to the ability to provide a downward flow of catalyst particles through the system. The catalytic reforming method generally employs a multi-stage treatment method, and each treatment step usually reduces the volume %
Different amounts of catalyst are included.

A reactant stream consisting of hydrogen and hydrocarbon feed flows sequentially through multiple reaction zones to increase catalyst volume while providing intermediate heating. In a system consisting of three reaction zones, a typical catalyst loading is 10.5% in the first zone.
0%~30.0%; 20.0%~40.0 in the second belt castle
%; and 40.0 to 60.0% in the third band.

In a system consisting of four reaction zones, suitable catalyst loadings are: 5.0% to 15.0% in the first zone: 15.0% to 25.0% in the second zone; 25.0%~ for Sannobi Castle
35.0%; and 35.0% to 50.0 to the fourth belt castle
%.

Such non-uniform catalyst distribution increasing in the direction of continuous flow of the reactant stream improves and enhances the distribution of the reaction as well as the overall heat of reaction. The lodging of catalyst particles toward the active center tube is primarily due to the large vapor velocity across the annular catalyst retention band, and this adverse effect is influenced by the cross-sectional area and length of the catalyst bed. increases as the value decreases.

Therefore, in a multistage catalytic reforming system, the effect is most noticeable in the first and second reaction zones with small annular cross-sectional areas, and is somewhat less effective in the third reaction zone. The fourth reaction zone has relatively little influence due to its length and larger cross-sectional area of the catalytic zone. Splitting the reactant streams (fresh hydrocarbon feedstock and recycled hydrogen) acts to reduce the material flow to each of the first two reaction zones. The relative amounts are, on a weight basis, 30.0-50.0% for the first reaction zone and 50.0-70.0% for the second reaction zone. A pressure drop from the first reaction zone to the second reaction zone is ensured by restricting the flow of the effluent from the first reaction zone and at the same time restricting the flow of the reactant stream introduced into the second reaction zone. Ru. In a four reaction zone conversion system, the effluent from the third reaction zone is restricted prior to introduction into the fourth reaction zone.

Restrictions on the flow of the multiple reaction zone effluents may be implemented in any suitable manner in which each restriction provides or results in an increase in pressure drop of about 0.07 to 0.7 atm over the entire reactor path. It may be done by method.

Similarly, restricting the flow of fresh feedstock and hydrogen to the second reaction zone results in an increased pressure drop of about 0.07 to 0.7 atmospheres. Flow restriction may be achieved using venturi tubes, control valves, orifice plates, etc., and the use of orifice plates is particularly preferred for gas phase processing. In many cases, the maldistribution of catalyst to the perforated central tube is a function of two interdependent variables: '1} Steam mass flow rate; and '2} The density of the vapor that enters the pore center tube and flows through it. In order to reduce the amount of unevenly distributed catalyst for a given set flow of fresh feed, the amount of hydrogen-rich gas recirculated into the system must be reduced. However, this reduces the total mass flow into a given reaction zone, which in turn reduces the reactor pressure drop. Of course, the effective pressure in the first reaction zone, where catalyst maldistribution is most prevalent and problematic, is reduced; as a result, there is a corresponding decrease in gas phase density. By using a restricting orifice plate (or other suitable means) as described above, the pressure drop in the reactor path is increased; thus promoting an increase in the pressure in the first reaction zone, and thus an increase in gas phase density. . If the vapor density increases, the problem of uneven distribution of the catalyst will be solved. The use of restricted orifice plates also allows for more recycle gas flow, thereby reducing the deposition of carbonaceous material on the charge to be regenerated provided to the regenerator. moreover,
The last reaction zone operates at lower pressures and therefore has the benefit of increased liquid yield. Preferably, the restriction orifice is located upstream of the intermediate heater in the reaction zone to reduce the operating pressure of the heater and increase the velocity of the reactor effluent within the heating tube. In other words, the mass flow to the first and second reaction zones is reduced, the gas phase density is increased, the pressure drop within the reactor system is increased, and the catalyst is unevenly distributed. Related problems and difficulties are resolved. Further description of the invention and its method of operation will now be described with reference to the accompanying drawings.

It should be understood that the drawings are for illustrative purposes only and are not intended to control the scope or spirit of the invention as defined in the claims. Accordingly, many accessories not necessary for a thorough understanding of the invention have been omitted or reduced in number. Such matters are a matter of course for those who have the necessary skills in the appropriate fields. The illustrated embodiment comprises an upper first reaction zone 1, two middle reaction zones R and M, and a lowermost fourth reaction zone W.
It is shown as a schematic flow chart showing a superimposed contact flow system 1 consisting of two reaction zones. The accompanying drawing shows a particularly preferred embodiment, in which a stacked reactor system 1 is composed of four individually separated reaction zones 1, 2, 2, 2 and 3.

Their size, that is, their length and the cross-sectional area of the annular catalyst region are 10.0% (Obijo 1), 15.0% (Obijo 0
), 25.0% (Obijo m) and 50.0% (Obijo W)
The distribution of the total catalyst volume is as follows. During normal, virtually problem-free operation, fresh or regenerated catalyst particles are introduced into the uppermost reaction zone 1 through conduit 2 and inlet 3, flow down the reaction zone 1 under the action of gravity, and then flow through the reaction zone 1. It flows from reaction zone 0 to reaction zone m and from reaction zone m to reaction zone N and is finally removed from this reactor system 1 via a plurality of outlets 4 and conduits 5 . The thus transferred catalyst particles may be transferred to a continuous regeneration zone (not shown) or may be stored until sufficient quantity is available for batchwise regeneration. The velocity of the catalyst flowing through the stacked reactor system 1, i.e. the time required for catalyst particles to be introduced into the system, pass through the four reaction zones and be removed for regeneration, depends on the rate at which regeneration takes place. It is determined. By monitoring various operating parameters while the system is continuously processed, the rate of catalyst removal and thus the amount charged to the regeneration belt can be controlled. A feedstock in the naphtha boiling range is introduced into the process system through line 6;
Mix with the hydrogen-rich gas phase from line 7.

After appropriate heat exchange with one or more hot process streams, the mixture is sent to heater 8 to further raise the temperature to the desired temperature at the catalyst bed inlet of reaction zone 1 and 2.

Of the heated reactant flow in line 9), 60% is separated into line 10' equipped with orifice plate 11 and introduced into the reaction zone, while the remaining 40% is passed directly from line 9 to reaction zone 1. send. The effluent from reaction zone 1 is in line 12 with orifice plate 13 and is mixed with the effluent from reaction zone 0 in line 14. In the illustrated example, the orifice plate 11 is adjusted to approximately 0.54 atmospheres, while the orifice plate 13 is adjusted to approximately 0.27 atmospheres. Therefore, a pressure drop from the reaction zone 1 to the reaction zone 0 is ensured, preventing steam back-up and ensuring proper catalyst flow. The reactor effluent mixture passes through conduit 12 to intermediate heater 1 of the reaction zone.
5 and is heated in the heater to the desired level at the catalyst bed inlet of the reaction zone m.

A conduit 17 with a restrictive orifice plate 18 set at 0.41 atmospheres carries the effluent from reaction zone m to a heater 19;
The heated mixture is introduced into the lowermost reaction zone W via conduit 20.

The reaction product stream from this reaction zone W at the bottom is taken off in line 21 and is utilized as a heating medium for the subheating of the fresh feed and recycled hydrogen in line 6. The product stream is sent to condenser 22 where approximately 1
Cooling and condensation takes place at a temperature of 60° C. to about 60° C. and the resulting mixture is sent via line 23 to separator 24 . Hydrogen-enriched vapor is removed through conduit 7 and at least a portion thereof is recycled via lines 7 and 6 to the uppermost reaction zone 1 and the middle reaction zone m. Excess hydrogen is taken out of the system through line 26, and its proportion is appropriately determined by pressure control. A normally liquid product stream is removed from line 25 and optionally sent to a fractionator (not shown). Although shown as a single separator 24 and condenser 22 in the illustrated example, line 23
Separation of the product effluent in may be carried out by first using a low pressure separator and then using a high pressure separator.

After compression, the vapor from the low pressure separator is mixed with the liquid material recovered from the low pressure separator and introduced into the high pressure cooler. This mixture is then introduced into a high pressure separator to recover the hydrogen-rich recycle gas phase and the normally liquid product effluent.

[Brief explanation of the drawing]

The accompanying drawings are process flow diagrams of the method of the present invention. 1, D, m, W: reaction zone, 1: reactor system, 11, 13
, 18: Orifice plate, 8, 15, 19: Heater, 22
: Condenser, 24: Separator.

Claims (1)

Claims: 1. A heated hydrocarbon feedstock and hydrogen flow sequentially through a plurality of catalytic reaction zones, between each successive reaction zone the reaction product effluent is heated, and within each reaction zone In a multi-stage catalytic conversion process in which catalyst particles are movable by gravity flow; (a) a first reaction zone in which the feedstock and hydrogen are heated and then a first portion thereof is maintained at hydrocarbon conversion conditions; (b) introducing a second portion of the heated feedstock and hydrogen into a second reaction zone maintained under hydrocarbon conversion conditions by restricting the flow of the second portion; (c) restricting the flow of the effluent from the first reaction zone and mixing this flow with the effluent from the second reaction zone; (d) heating the resulting mixture to introducing the mixture into a third reaction zone maintained at hydrocarbon conversion conditions; (e) separating the effluent from the last reaction zone in the system to form (i) a normally liquid product stream; ii) providing a hydrogen-enriched gas phase and recycling at least a portion of said gas phase to said first reaction zone;
f) at least periodically removing catalyst particles from the last reaction zone in the system; and (g) following the step of at least periodically introducing fresh or regenerated catalyst particles into the first reaction zone in the system. A method for the catalytic conversion of a hydrocarbon feedstock, comprising stages. 2. According to claim 1, wherein a plurality of said reaction zones in the conversion reaction system are arranged one after the other, and the catalyst particles are transferred from the bottom of one reaction zone to the top of the next successive reaction zone. Method described. 3. A patent in which a plurality of said reaction zones in a conversion reaction system are stacked and share the same vertical axis so that catalyst particles flow from one reaction zone to the next lower reaction zone under the action of gravity. A method according to claim 1. 4. The method according to any one of claims 1 to 3, wherein the conversion reaction system has three catalytic reaction zones. 5. The method according to any one of claims 1 to 3, wherein the conversion reaction system has four catalytic reaction zones. 6. The method of claim 5, wherein the flow of effluent from the third reaction zone is restricted prior to introduction into the fourth reaction zone. 7. The method of claim 6, wherein restricting the flow of effluent from the third reaction zone further provides a pressure drop within the reaction system of about 1.0 to about 10.0 psi. . 8 further by restricting the flow of said feedstock and said second portion of hydrogen from about 1.0 to about 10
．． 8. A method according to any of claims 1 to 7, wherein a pressure drop of 0 psi is provided within the reaction system. 9 by restricting the flow of effluent from said first reaction zone, further from about 1.0 to about 10.0 psi.
9. A method according to any one of claims 1 to 8, characterized in that a pressure drop of g g is brought into the reaction system. 10. The method according to any one of claims 1 to 9, wherein the multistage catalytic conversion system comprises a multistage hydrocarbon catalytic reforming process.