WO1998039095A1

WO1998039095A1 - Method for regenerating paraffin reforming or isomerization or dehydrogenation catalysts in a vibrating helical spire

Info

Publication number: WO1998039095A1
Application number: PCT/FR1998/000372
Authority: WO
Inventors: Olivier Clause
Original assignee: Institut Français Du Petrole
Priority date: 1997-03-04
Filing date: 1998-02-25
Publication date: 1998-09-11
Also published as: BR9808164A; JP2002511791A; FR2760386A1; CN1249700A; EP0969923A1; FR2760386B1; KR20000075923A

Abstract

The invention concerns the application of a method for regenerating catalysts or adsorbents, consisting in causing the catalyst particles to rise in a vibrating helical elevator (12), said particles being subjected to a temperature profile and being contacted with one or several fluids over part of their travel in said spire, regenerating paraffin reforming, isomerization or dehydrogenation catalysts. The helical elevator can be maintained at the appropriate temperature by circulating gas at the required temperature outside and in contact with the helical elevator, The regenerator comprises at least a combustion zone (14) and at least an oxychlorination (15) or more generally a chlorination zone, which can be merged. A pre-heating zone (13), a hydrocarbon stripping zone, a calcining zone (16) and a cooling zone for the catalyst can also be included in the device.

Description

REGENERATION OF CATALYSTS FOR REFORMING OR DTSOMERIZATION OR DEHYDROGENATION OF PARAFFINS IN A VIBRANT HELICOID SPIRE

The present invention relates to the application to processes of catalytic reforming, isomerization of paraffins or dehydrogenation of paraffins with preferably continuous regeneration of the catalyst, of a process described in the prior art, consisting in raising the particles of catalysts in at least one vibrating helical turn, subjecting them over at least part of their path and preferably over most of their path to a temperature profile and putting them in contact with at least one fluid on at least one part of their journey.

One possible application is catalytic reforming which is a process consisting in increasing the octane number of gasolines by promoting the reactions of dehydrogenation of naphthenes, isomerization of alkylnaphthenes and paraffins, and dehydrocyclization of paraffins. The paraffin dehydrogenation process makes it possible to obtain olefins having the same number of carbon atoms as the starting paraffins. These olefins can be used later for the production of bases for super fuels (ethers, alkylates) or biodegradable detergents. The paraffin reforming and dehydrogenation processes use solid catalysts based on precious metals such as platinum or rhenium or oxides such as molybdenum oxide or chromium oxide, supported on a refractory oxide such as alumina.

Over time, these catalysts deactivate due to the progressive deposition of polyaromatic hydrocarbons of complex structure bearing the usual name of coke. The deposition of coke requires regeneration of the catalyst after an operating cycle ranging from a few days to more than a year. In units with continuous catalyst regeneration, it is not necessary to stop the units in order to regenerate the catalyst. The catalyst is transported from one reactor to another by an adequate means, of a mechanical or pneumatic nature, then it is transported to a regeneration column operating the rejuvenation of the catalyst, finally the regenerated catalyst is transported to one or more reactors, preferably the regenerated catalyst is transported to the head of the first reactor. The regenerator according to the invention can also be used off-site, for example the catalyst can be transported to a company specialized in the treatment of catalysts where it will be regenerated.

The regeneration of reforming catalysts, isomerization of paraffins or dehydrogenation of paraffins can comprise several stages, for example in the case of the reforming of a stage of combustion of coke intended to remove the hydrocarbon deposit by combustion managed in an oxidizing medium, a chlorination step (and in particular oxychlorination) intended to improve the dispersion of the metallic active phase (in the case of platinum-based catalysts) and optionally a calcination step intended to improve the fixation of the active phase, dry the catalyst and set its chlorine content to the value required for optimal catalytic performance. A step of cooling the catalyst in air or under nitrogen as well as a step of stripping the hydrocarbons trapped in the porosity of the catalyst under a stream of inert or neutral gas, for example under nitrogen, can also follow the calcination step.

All these steps are implemented successively in existing processes for the continuous regeneration of reforming catalysts.

In these processes, for example the Octafining process of the Institut Français du

Oil or the CCR Platforming process from UOP, the catalyst flows by gravity from top to bottom of a column called regenerator, for example RegenC from IFP or CycleMax from UOP, successively passing through areas where the combustion stages, oxychlorination. calcination and cooling described above. This makes it necessary to transport the catalyst from the bottom of the last reforming reactor crossed by the charge to the top of the regenerator, then to transport the catalyst from the bottom of the regenerator to the top of the first reforming reactor crossed by the charge or the reducing agent (zone of reduction of the catalyst at the inlet of the V reforming reactor). These transportations of catalysts operated, for example by gaseous lifts, are liable to progressively deteriorate the catalyst, for example by generating fines and dust or by breaking up catalyst particles.

The implementation of the method according to ^the invention derived from a known method of the prior art, avoids the implementation of a method of transport of catalyst to the top of the regenerator and from the bottom of the regenerator. The apparatus for implementing the process is in fact a regenerator supplied by the catalyst in its lower part, the regenerated catalyst leaving at the top of the regenerator. So at the same time as the catalyst is regenerated, it is simultaneously carried up to the top of the \ ^κ reaction reforming zone. These reaction zones are generally placed side by side or superimposed, the charge and the catalyst generally circulating successively from top to bottom through each reaction zone. This same type of arrangement can also be used for the dehydrogenation or isomerization of paraffins. This device is a vibrating spiral elevator ^that is to say a vibrating elevator comprising at least one turn and a helical ramp substantially tubular. The device can be used in a catalytic reforming process in a circulating bed, or during the off-site regeneration of reforming catalyst. The catalyst particles rising within the coil are subjected to a temperature profile over part of their path, as described in the French patent application filed under the number FR 94/3865. This temperature profile can be obtained by indirect contact with a heat transfer fluid bathing the steps of the coil, as described in French patent application FR 2 634 187. In this patent application, the turns of the helical ramp are connected to each other by two helical bands, fixed to the ramp on two opposite sides thereof to form a helical channel, between the turns of the helical ramp, in which a heat transfer fluid can circulate. More generally, as described in French patent application FR 94/3865, the entire tube-coil device may be placed in an enclosure, where the products transported will be subjected to a heat treatment, for example a insulated enclosure in which circulates a heat transfer fluid bathing the steps of the coil. It follows from the same patent application that the heat transfer fluid can pass through the coil itself. This gas can circulate cocurrently or countercurrently. Heating of the turn can also be obtained by the Joule effect, by directly heating the metallic mass of the tube as described in European patent application EP-A-0,612,561.

The present invention relates to a method of treating a catalyst selected from the group consisting of reforming catalysts, ^{isomerization} of paraffins and dehydrogenation of paraffins or a powdery adsorbent. Said method consists in mounting the particles of catalyst or adsorbent in a vibrating helical elevator comprising at least one vibrating helical coil and in which are arranged at least one combustion zone and at least one chlorination zone. According to said method, the particles are also subjected to a temperature profile over at least part of their path, path during which they are brought into contact with at least one fluid. The method according to the invention therefore relates to a treatment included in the group formed by regenerations, activations, reactivations of catalysts, and comprises at least one combustion step carried out in at least one combustion zone and at least one chlorination step. performed in at least one chlorination zone.

By rising in the helical elevator, the catalyst successively passes through a coke combustion zone, where a flow of air or oxygen is introduced in a stepwise fashion at the level of several successive turns, so as to limit the concentration of oxygen and not to risk degrading the catalyst by local overheating, a chlorination zone where a chlorinating agent such as perchlorethylene is introduced with air and, possibly a calcination zone where the catalyst is swept by a stream of nitrogen or dry air containing less than 50 ppm water.

It is possible to combine the combustion and chlorination zones in a single zone, by introducing the chlorinating agent at the bottom of the combustion zone.

Advantageously, the combustion zone is preceded by a zone in which the catalyst is preheated so that its temperature reaches a level where the subsequent combustion of the coke takes place under optimal conditions.

It is also possible to modulate the injections of air or oxygen into the coke combustion zone, by introducing, for example, increasing amounts of air from the bottom to the top of the helical elevator. The temperatures of the gases entering the combustion zone can be between 300 and 750 ° C. preferably between 450 and 550 ° C. It is also possible to extract part of the combustion gases by means of purges placed in one or more places of the elevator as it is, for example described in example 2.

The turn or turns if there are several, has at least 2 steps and is wound around a hollow shaft in which is arranged a system intended to produce vibrations, for example an unbalance motor as described in the request. French patent FR 94/3865. The turns can be contiguous or non-contiguous. The gases or fluids intended for the regeneration of reforming catalysts, of isomerization of paraffins or of dehydrogenation of paraffins can be introduced by one or more conduits so that said gases or fluids circulate in co-or counter-current in one or more not from the turn. The pressure within the coil can be between 0, 1 and 20 bars, preferably between 1 and 7 bars. The gases or fluids can be introduced into the coil laterally, from above or from below the coil by passing through a fine-mesh grid or any suitable device intended to prevent the ingress of particles of catalyst in the inlet pipes. gases. The same applies to the gas withdrawal line (s).

The figures and examples described below illustrate the invention without limiting its scope.

Figure 1 illustrates Example 1 described below. The helical elevator (12) is arranged on a vibrating table (1) and two unbalance motors (2) generate the vibrations necessary for the rise of the catalyst.

The entry of solid particles takes place via line (3) and the exit of particles through line (4). The helical drum-lift assembly is contained in a thermally insulated enclosure secured to the vibrating table (5). A gas is introduced at the top of the device through the pipe (6). Said gas bathes the first turns of the helical elevator: this gas is introduced at (7) laterally at the bottom of the helical elevator, and passes through this helical elevator co-current with the catalyst. Air is introduced through six lines

(8) in the combustion zone (14). The first air inlet pipe is positioned laterally at the level of the second turn of the helical elevator. The catalyst then enters the chlorination zone (zone 15). gas is also introduced into this zone through line (9). The pipes (8), (9) and (1 1) are supplied by pipes and a device located inside the central barrel. The gas from the combustion and chlorination zones leaves the helical elevator through the line (10). The catalyst then enters the calcination zone (zone 16), in this zone, the catalyst is swept against the current by dry air introduced through the conduit (1 1). The calcination gas leaves the helical elevator through the pipe (10) together with the combustion and chlorination gases.

FIG. 2 shows an embodiment of the method according to the invention in which the combustion zone comprises a series of pipes for discharging the combustion gas.

Figure 2 illustrates Example 2. The helical elevator (10) is arranged on a vibrating table (1) and two unbalanced motors (2) generate the vibrations necessary for the rise of the catalyst. The entry of solid particles takes place via line (3) and the exit of particles through line (4). An air-containing gas is introduced cocurrently from the catalyst flow through line (3). An air-containing gas is also introduced through 7 pipes (5) into the combustion zone. The combustion gas is drawn off by means of 7 pipes (6). Passing through the combustion zone (12), the catalyst is therefore supplied with a combustion gas alternately co-current and counter-current. The vibrating elevator is heated by the Joules effect as described in European patent application EP-A-0,612,561. The catalyst is preheated in the coil of the zone (1 1) which is insulated.

The catalyst then enters the chlorination zone (zone 13) a gas circulating against the current with respect to the direction of circulation of the catalyst, is also introduced into this zone via the pipe (8). The gases from the combustion and chlorination zones exit the helical elevator via the lines (6) and (7).

The catalyst then enters the calcination zone (zone 14). in this zone, the catalyst is swept against the current by dry air introduced through the conduit (9). The supply of lines (5), (8) and (9) is provided by pipes and a device located inside the central barrel The calcining gas leaves the helical elevator by the pipe (7) together with the combustion and chlorination gases

FIG. 3 shows an embodiment of the method according to the invention in which the combustion and chlorination zones are combined

According to this embodiment, the helical vibrating elevator (9) is arranged on a vibrating table (1) and two unbalanced motors (2) generate the vibrations necessary for the rise of the catalyst. Solid particles enter via line (3) and particles exit via line (4)

The zone (10) is a zone in which the catalyst is preheated by means of a stream of nitrogen introduced at the bottom of the vibrating elevator. The pipe (5) makes it possible to introduce the nitrogen into the pipe (3).

The catalyst passes through the zone (1 1) of the regenerator, which is both a combustion zone and a chlorination zone and in which a burning and a redispersion of the bimetallic phase of the catalyst are carried out simultaneously. A gas containing hydrogen chloride is introduced into each of the turns making up the zone (1 1) by six pipes (6), the gas is then withdrawn from this zone by means of six pipes (7). The catalyst then enters the calcination zone (12) in which it is swept by a stream of dry air introduced into this zone by the pipe (8) The calcination gas leaves the zone (12) by the pipes (7 ).

Example 1:

The catalyst of Example 1 is regenerated in a regenerator in accordance with FIG. 1.

The catalyst is in the form of spherical beads with a diameter of 1.8 mm, it comprises a metallic phase of platinum dispersed on alumina, the platinum content being 0.30% by weight The metal surface exposed before regeneration is 81%. The specific surface of the catalyst is 200 m2 / g The catalyst enters the regenerator at a temperature of 350 ° C at a flow rate of 500 kg / h. Its carbon content (coke) is 6.0% by weight.

The first steps of the helical elevator are bathed in a flow of nitrogen used for preheating (zone 13) of the catalyst. This nitrogen flow is introduced in (7) at a flow rate of 500 Nm 3 / h, at a pressure of 5 bars, this gas is preheated to 480 ° C. by means of an oven external to the device.

The catalyst passes through the coke burning zone (14). Each of the pipes (8) deliver a flow of 40 Nm3 / h of air preheated to 480 ° C.

The residence time of the catalyst in the combustion zone (zone 14) is 30 minutes, ie a tube length of 60 m. The catalyst then enters the chlorination zone which is here an oxychlorination zone (zone 15), the line (9) allowing the introduction of an air flow containing perchlorethylene at a flow rate of 500 Nm3 / h. The residence time of the catalyst in the oxychlorination zone is 30 minutes, ie a tube length of 60 m. The catalyst then enters the calcination zone (zone 16). The residence time of the catalyst in the calcination zone is 15 minutes, ie a tube length of 30 m. The catalyst is swept against the current by a stream of dry air at 500 Nm3 / h introduced at the top of the regenerator through line (1 1).

The characteristics of the catalyst at the outlet of the regenerator are as follows: specific surface, 195 m2 / g; dispersion of the metallic phase, 95%; 0.1% carbon content. The mechanical characteristics of the catalyst balls (resistance to attrition, crushing grain to grain) are unchanged. The chlorine content is 1.2% by weight. The device described in Example 1 therefore allows complete regeneration of the reforming catalyst.

Example 2

The catalyst of Example 2 is regenerated in a regenerator in accordance with FIG. 2. The catalyst is in the form of spherical beads with a diameter of 1.6 mm, it comprises a metallic phase of platinum dispersed on alumina, the platinum content being 0.28% by weight. The metal surface exposed before regeneration is 81%. The specific surface of the catalyst is 220 m2 / g.

The catalyst enters the regenerator at a temperature of 350 ° C at a flow rate of 500 kg / h. Its carbon content (coke) is 6.0% by weight.

The catalyst passes through the coke burn zone. An air flow of 50 NmVh is introduced through line (3), into the combustion zone, it circulates co-current with the catalyst flow. This gas is introduced at room temperature. Air at room temperature is also introduced by means of the 7 pipes (5), the air flow rate of each of these pipes being 50 Nm3 / h. This gas then exits by means of the pipes (6) each drawing a flow rate of 50 Nm3 / h.

The average temperature in the catalytic bed in the coke combustion zone is adjusted in the window 480-550 ° C. The coils in the combustion zone are not insulated. The catalyst enters the elevator at a temperature of 150 ° C at a flow rate of 500 kg / h. Its carbon content (coke) is 6.0% by weight.

The residence time of the catalyst in the combustion zone (zone 12) is 30 minutes, ie a tube length of 60 m. The catalyst then enters the oxychlorination zone (zone 13), the pipe (8) introducing a flow rate of 500 Nm3 / h of air containing a mixture of dichloroethane and water. The residence time of the catalyst in the oxychlorination zone is 30 minutes, ie a tube length of 60 m. The catalyst then enters the calcination zone (zone 14), the stream of dry air introduced into this zone against the current of the catalyst has a flow rate of 500 Nm 3 / h. The residence time of the catalyst in the calcination zone is 15 minutes, ie a tube length of 30 m.

The characteristics of the catalyst at the outlet of the regenerator are as follows: specific surface, 220 m 2 / g: dispersion of the metallic phase. 95%; carbon content 0.05%. The mechanical characteristics of the catalyst balls

(attrition resistance. grain-to-grain crushing) are unchanged. Content chlorine is 1.0% by weight. The device described in Example 2 therefore allows complete regeneration of the reforming catalyst.

Example 3:

The catalyst of Example 3 is regenerated in a regenerator according to FIG. 3 in which the combustion and the chlorination are carried out in the same zone.

The catalyst is in the form of extrudates with a diameter of 1.4 mm and a length of between 1 and 8 mm. It comprises a metallic phase of platinum and rhenium dispersed on alumina, the platinum content is 0.25% by weight and the rhenium content is 0.30% by weight. The metal surface exposed before regeneration is 75%. The specific surface of the catalyst is 230 m2 / g. The catalyst enters the regenerator at a temperature of 140 ° C. at a flow rate of 300 kg / h. Its carbon content (coke) is 12.0% by weight.

The catalyst is preheated to the temperature of 515 ° C. in the first turns constituting the zone (10) by means of a flow of nitrogen having a flow rate of 20 Nm 3 / h, at a pressure of 6 bars. The catalyst then passes through the zone (1 1) of the regenerator. In this zone, an air flow containing hydrogen chloride is introduced into each of the turns making up the combustion zone through six pipes (6) at a flow rate of 80 Nm3 / h. Each of the air additions is introduced at a temperature of 400 ° C. and at a pressure of 5.9 bars. The combustion air is heated and compressed by an oven and a compressor external to the device. Hydrogen chloride is obtained by temperature decomposition of dichloropropane between the oven and the regenerator. The residence time of the catalyst in this zone (1 1) is 40 minutes. This zone (1 1) is, in addition, heated to the temperature of 550 ° C. by the Joules effect as described in patent EP-A-0,612,561.

The catalyst then enters the calcination zone (12), in this zone, it is swept against the current by a stream of dry air introduced at the top of the regenerator by the line (8) at a flow rate of 50 Nm3 / h and at a temperature of 525 ° C. The residence time of the catalyst in this zone is 15 minutes. The characteristics of the catalyst leaving the regenerator are as follows: specific surface, 210 m2 / g; 95% bimetallic phase dispersion: carbon content less than 0.05. The amount of small catalyst particles - called "fine" by those skilled in the art - produced during regeneration is less than 0.1% by weight. The regeneration of the reforming catalyst is therefore complete.

Claims

1 A method of treating ^a catalyst selected from the group LORME by léformage catalysts. isomerization of affine or dehydrogenation of affine or a pulverulent adsorbent. consisting in raising the particles of catalyst or adsorbent in a vibrating helical elevator comprising at least one vibrating helical coil and in which are arranged at least two zones, process in which said particles are further subjected to a temperature profile on at least part of their path, path during which they are brought into contact with at least one fluid, method characterized in that in that said alternating ti is included in the group formed by regenerations, activations, reactivations of catalysts. said treatment comprising at least one combustion step carried out in at least one combustion zone and at least one chlorination step carried out in at least one chlorination zone.

2. Method according to claim 1 characterized in that the regeneration or activation or reactivation of catalysts is carried out continuously

3 Method according to claim 1 or 2 characterized in that at least one combustion zone and at least one chlorination zone are distinct and superimposed in the vibrating helical coil.

4 Method according to one of the preceding claims characterized in that at least one combustion zone and at least one chlorination zone are combined.

5 Method according to one of the preceding claims cai acténsé in that it further comprises at least one calcination step lahahée in at least one calcination zone

6 Method according to claim 5 characterized in that the catalyst successively undergoes at least one combustion step in the presence of a combustion gas, then at least one chlorination step in the presence of a chlorination gas then at least one calcination step in the presence of a calcining gas

7. Method according to one of the preceding claims characterized in that it further comprises at least one step of stripping the hydrocarbons carried out before the combustion step.

8. Catalytic process chosen from the group formed by reforming, isomerization of paraffins and dehydrogenation of paraffins carried out in several reaction zones in series, superimposed or side by side, the charge and the catalyst flowing successively through each reaction zone from above below, the catalyst withdrawn at the bottom of the last reaction zone traversed by the charge then being treated according to the method of claim 1, then being withdrawn from the top of said turn and sent to the first reaction crossed by said charge.

9. Installation comprising: • at least one vibrating helical elevator, comprising at least one turn, a helical ramp of substantially circular shape, at least one catalyst introduction pipe and at least one catalyst outlet pipe, this helical elevator being disposed on a vibrating table, • at least one combustion zone in which is arranged at least one turn of the vibrating helical elevator comprising at least one gas introduction pipe and at least one gas outlet pipe,

• at least one chlorination zone in which is disposed at least one turn of the vibrating helical elevator comprising at least one gas introduction pipe and at least one gas outlet pipe.

10. Installation according to claim 9 comprising at least one calcination zone located above the combustion and chlorination zones in which is disposed at least one turn of the vibrating helical elevator comprising at least one gas introduction pipe and at least one gas outlet pipe.

1 1. Installation according to claim 9 or 10 wherein the combustion and chlorination zones are combined.