EP4204135A1

EP4204135A1 - Integrated reactor-exchanger with two levels of fixed beds in series and related method

Info

Publication number: EP4204135A1
Application number: EP21762058.2A
Authority: EP
Inventors: Alain BENGAOUER; Albin Chaise; Julien Cigna; Michel Jouve
Original assignee: Commissariat a lEnergie Atomique CEA; Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Current assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Priority date: 2020-08-27
Filing date: 2021-08-25
Publication date: 2023-07-05
Also published as: FR3113612B1; WO2022043401A1; FR3113612A1

Abstract

The invention relates to a catalytic synthesis reactor-exchanger (1) comprising a first reactor (2) that is suitable for receiving a first catalyst fixed bed (7), and a second reactor (3) that is suitable for receiving a second catalyst fixed bed (11), the first reactor (2) and the second reactor (3) being arranged in series, characterized in that the second reactor (3) is arranged inside the first reactor (2) such that the second reactor (3) is in contact with the first catalyst fixed bed (7) of the first reactor (2) in order that heat-transfer fluid is not required to provide a heat exchange between the first reactor (2) and the second reactor (3). The present invention relates to the field of catalytic reactors. It applies in a particularly advantageous manner to the field of catalytic reactors that use solid catalysts and dedicated to exothermic or endothermic reactions.

Description

INTEGRATED REACTOR-EXCHANGER WITH TWO STAGES OF FIXED BEDS IN SERIES AND ASSOCIATED METHOD

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the field of catalytic reactors. The invention relates to a catalytic synthesis reactor-exchanger. It finds a particularly advantageous application in the field of catalytic reactors using solid catalysts and dedicated to exothermic or endothermic reactions. More specifically, the invention allows the implementation of processes for the synthesis of fuels and fuels (SNG: synthetic natural gas from English Synthetic Natural Gas, DME: dimethyl ether, MeOH: Methanol) from hydrogen and carbon oxides or from synthesis gas (mixture of hydrogen and carbon oxides).

STATE OF THE ART

Catalytic reactors are the subject of many industrial achievements.

Conventional architectures of catalytic systems include several conversion reactors arranged in series or in parallel as well as gas preheating, reactor cooling and cooling and condensation of the gases after reaction using a circulation of fluid: generally a thermal oil, water or molten salts.

The main types of reactors known for exothermic reactions are:

Fluidized bed reactors which offer the advantage of good thermal homogeneity in the reactor which avoids hot spots, but requires a larger reactor volume than in the case of plug-flow fixed beds. In these reactors, the catalyst is in the form of fine particles whose attrition must be controlled.

Adiabatic fixed bed reactors placed in cascade in which the exothermicity is then generally managed by a dilution of the reactants at the inlet of the first reaction stage (for example by recirculation of the products) and by the installation of heat exchangers intended cooling the reactant-product mixture between the various reactors. This architecture has the advantage of manufacturing simplicity, but makes thermal control difficult and requires the use of catalysts that are stable at high temperature.

Reactor-exchangers in which the chemical reaction takes place within a reactive channel continuously cooled by a heat transfer fluid, most of these reactors are of the shell-tube type, the reaction occurring in the reaction tubes cooled at the periphery by a heat bath. Depending on the technology chosen for cooling, these reactors can be isothermal or anisothermal.

Document US Pat. No. 4,298,694 discloses a device combining an adiabatic fixed-bed reactor and an isothermal reactor-exchanger, each of which treats part of the gas inlet stream in order to recover the heat of reaction in the form of superheated steam (obtained by a exchanger connected at the outlet of the adiabatic stage) while producing a gas with a high methane content thanks to the low temperature obtained at the outlet of the isothermal reactor.

In this type of high power or medium power applications, a separation of the preheating, reaction and cooling functions for each reactor is generally retained. This separation when applied to low power installations and/or using renewable energies leads to a significant energy expenditure leading to an unfavorable energy yield.

An object of the present invention is therefore to provide a reactor system whose energy efficiency is optimized to allow its use in small-scale installations and/or using renewable energy as an energy source.

The other objects, features and advantages of the present invention will become apparent from a review of the following description and the accompanying drawings. It is understood that other benefits may be incorporated.

SUMMARY OF THE INVENTION

To achieve this objective, the invention provides a catalytic synthesis reactor-exchanger comprising a first reactor capable of receiving a first fixed bed of catalyst, and a second reactor capable of receiving a second fixed bed of catalyst, the first reactor and the second reactor being arranged in series, characterized in that the second reactor is arranged inside the first reactor so that the second reactor is in contact with the first fixed catalyst bed of the first reactor to ensure heat exchange between the first reactor and the second reactor. The heat exchange is direct. Advantageously, the heat exchange does not require heat transfer fluid.

The reactor-exchanger according to the invention thus makes it possible to thermally integrate the heating and reaction functions of the two reactors of the reactor-exchanger. The integration of the heating and reaction functions is also mechanical. The second reactor being arranged inside the first to form a single reactor-exchanger and therefore limit heat losses and increase the compactness of the assembly.

The advantage of the present invention is on the one hand the absence of heat transfer fluid, preferably other than the ambient air, on the other hand the simplicity and compactness since a single component makes it possible to ensure the four heating functions and reaction for two reactors.

Thanks to this mechanical and thermal integration, the reactor-exchanger makes it possible to guarantee a maximum conversion rate, good selectivity and good temperature control so as to limit the deactivation of the catalysts.

In addition, in the case of highly exothermic reactions, thermal management is optimal in the exchanger reactor according to the invention. Indeed, the evolution of the temperature in the reactor conditions the degree of conversion and the selectivity of the reaction as well as the kinetics of deactivation of the catalyst. However, the reaction kinetics are stronger at high temperature according to the Arrhenius law, but the reactions being balanced and exothermic, the thermodynamic equilibrium is more favorable at low temperature. Optionally, the reactor-exchanger can also have a heating module arranged outside the first reactor.

Another aspect relates to a catalytic synthesis process in a catalytic synthesis exchanger reactor as described above comprising

• The injection of reagents into a first reactor through an inlet,

• The reaction of the reactants in the first fixed bed of catalyst,

• The output of unreacted products and/or reagents via an output from the first reactor,

• The transfer of thermal energy from the first reactor to the second reactor by direct contact,

• Injection of all or part of unreacted reactants and/or products and/or reactants from the first reactor into the second reactor through an inlet,

• The reaction of the reactants in the second fixed bed of catalyst

• The outlet of unreacted products and/or reagents out of the second reactor via an outlet.

BRIEF DESCRIPTION OF FIGURES

The aims, objects, as well as the characteristics and advantages of the invention will emerge better from the detailed description of an embodiment of the latter which is illustrated by the following accompanying drawings in which:

FIG. 1 represents a perspective view of a reactor-exchanger according to the invention.

Figure 2 a longitudinal sectional view of a reactor-exchanger according to Figure 1.

FIG. 3 represents an axisymmetric geometric model of a two-stage integrated reactor-exchanger according to FIG. 2. The ordinate axis represents the distance along the longitudinal axis of the first reactor, the inlet of the second reactor being the point 0 The abscissa axis represents the distance along the radial axis of the reactor-exchanger, the center of the first reactor being the point 0.

Figure 4 shows a temperature map for a GHSV (Gas hourly space velocity) of 2270h-1 according to the model in Figure 4.

FIG. 5 represents a simulation of the evolution of the temperature at the center of each fixed bed and of the conversion rate along the two reactors for GHSVs of 750, 1510, 2270 and 3020 h-1. Figure 6 represents a simulation of the evolution of the temperature in the center of the first fixed bed, 4 cm from its proximal end for different powers from 50 to 250 W

The drawings are given by way of examples and do not limit the invention. They constitute schematic representations of principle intended to facilitate understanding of the invention and are not necessarily scaled to practical applications.

DETAILED DESCRIPTION OF THE INVENTION

Before starting a detailed review of embodiments of the invention, optional characteristics are set out below which may possibly be used in combination or alternatively:

According to one example, the catalytic synthesis reactor-exchanger 1 comprises a connection circuit 24 configured to ensure the fluid connection of the first reactor 2 to the second reactor 3, the connection circuit 24 being arranged outside the first reactor.

According to one example, the first reactor 2 comprises an inlet 12 configured to ensure the entry of reactants into the first reactor 2 and an outlet 13 configured to ensure the outlet of unreacted products and/or reactants out of the first reactor 2 , and the second reactor 3 comprises an inlet 14 configured to ensure the entry into the second reactor (3) of all or part of unreacted reactants and/or reactants from the first reactor 2 and/or products from the first reactor 2 and an outlet 15 of unreacted products and/or reactants from the second reactor 3, the outlet 13 of the first reactor 2 is fluidically connected to the inlet 14 of the second reactor 3 by the connection circuit .

According to one example, the inlet 12 of the first reactor 2 and the inlet 14 of the second reactor 3 are arranged at a first end, respectively of the first reactor 2 and of the second reactor 3, the outlet 13 of the first reactor 2 and the outlet 15 of the second reactor 3 are arranged at a second end, respectively of the first reactor 2 and of the second reactor 3 opposite the first end.

According to one example, the catalytic synthesis reactor-exchanger 1 comprises a processing module arranged at the output of the first reactor 2 on the connection circuit 24 configured to ensure processing of unreacted products and/or reactants at the output of the first reactor 2 before their introduction into the second reactor 3. According to one example, the second reactor and the first reactor are concentric.

According to one example, the first reactor comprises a first tube defining an interior volume configured to receive the second reactor and the first fixed bed of catalyst. Advantageously, the first fixed bed is in contact with the second reactor. Preferably, the contact is configured to provide heat exchange between the first fixed bed and the second reactor. Thus, the transfer of thermal energy can be done either from the first fixed bed which transfers calories, resulting from an exothermic reaction or from heating to the second reactor or vice versa from the second reactor to the first fixed bed.

According to one example, the first reactor comprises an inlet configured to ensure the entry of reactants into the first reactor and an outlet configured to ensure the outlet of unreacted products and/or reactants from the first reactor, advantageously the inlet and the outlet being arranged radially on the first tube. The reactants are introduced into the first reactor 2 advantageously in the gaseous state, preferably the various reactants being already mixed. At the outlet of the first reactor 2, the unreacted products and/or reactants are advantageously in the gaseous state.

According to one example, the second reactor comprises a second tube arranged in the interior volume of the first reactor and defining an interior volume configured to receive the second fixed bed of catalyst.

According to one example, the second reactor comprises an inlet configured to ensure the entry into the second reactor of all or part of the reactants and/or unreacted reactants originating from the first reactor and/or products originating from the first reactor and an outlet for unreacted products and/or reactants from the second reactor, advantageously the inlet and the outlet are arranged radially or axially on the second tube. The reactants and/or products introduced into the second reactor 3 are advantageously in the gaseous state. At the outlet of the second reactor 3, the unreacted products and/or reactants are advantageously in the gaseous state.

According to one example, a proximal end of the first fixed catalyst bed arranged facing the inlet of the first reactor is axially offset with respect to a proximal end of the second fixed catalyst bed arranged facing the inlet of the second reactor, preferably offset along the longitudinal axis 20 of the first reactor 2. Said ends are offset along a longitudinal axis extending parallel to the main direction of the first reactor and the second reactor. The main direction of the first reactor and of the second reactor is understood as the direction in which the largest dimension of said reactors extends. Preferably, the first fixed bed comprises two opposite ends, including a proximal end and a distal end. Preferably, the second fixed bed comprises two opposite ends, including a proximal end and a distal end.

According to one example, the proximal end of the first fixed bed is arranged upstream of the proximal end of the second fixed bed. Thus, the cooling of the first fixed bed is carried out by heat transfer of calories from the first fixed bed to the second reactor.

According to one example, the reactor-exchanger comprises a heating module arranged in direct contact with the exterior of the first reactor.

According to one example, the heating module is arranged on a first portion of the first tube of the first reactor of dimension less than the total length of the first tube of the first reactor.

According to one example, the reactor-exchanger comprises a condensation module arranged at the outlet of the first reactor configured to ensure the condensation of water produced in the first reactor.

According to one example, the reactor-exchanger comprises a phase separation device arranged at the outlet of the condensation module configured to separate the liquid phase from the gaseous phase intended to be reintroduced into the second reactor.

According to one example, the synthesis process comprises the heating of a first portion of the first reactor by a heating module, preferably, the heating is carried out before, during and/or after the injection of reactants into the first reactor via an inlet.

According to one example, the synthesis process comprises the circulation of the products and/or of the unreacted reactants in the first reactor 2 and in the second reactor 3 in co-current.

According to one example, the synthesis process comprises the circulation of the unreacted products and/or reactants coming from the first reactor 2 in a connection circuit 24 arranged outside the first reactor 2 and fluidly connected to the inlet 14 the second reactor 3. According to one example, the synthesis process comprises the condensation of the products resulting from the first reactor before injection into the second reactor by a condensation module.

According to one example, the synthesis process comprises the separation of a liquid phase and a gaseous phase after condensation and before the injection of the gaseous phase into the second reactor by a phase separation device.

Upstream and downstream at a given point are taken with reference to the direction of fluid circulation.

The invention relates to a reactor-exchanger 1 for the implementation of catalytic synthesis reactions.

The reactor-exchanger 1 according to the invention comprises at least two reactors.

A first reactor 2 configured to receive a first fixed bed of catalyst 7. The first reactor 2 comprises a reaction chamber receiving the first fixed bed of catalyst 7. The first reactor 2 is intended to be the seat of at least one catalytic reaction.

The first reactor 2 comprises an inlet 12 and an outlet 13. The inlet 12 is intended to allow the entry of the reactants into the first reactor 2. The reactants come into contact with the first fixed bed of catalyst 7. The outlet 13 is intended to allow the products of the catalytic reaction and possibly the unreacted reactants to leave the first reactor 2. Preferably, the inlet 12 opens outside the first reactor 2 to allow reactants to be brought into the first reactor 2. Preferably, the outlet 13 opens outside the first reactor 2 to allow the products and/or unreacted reactants to leave the first reactor 2.

The reactor-exchanger 1 according to the invention comprises a second reactor 3 configured to receive a second fixed bed of catalyst 11. The second reactor 3 comprises a reaction chamber receiving the second fixed bed of catalyst 11. The second reactor 3 is intended to be the seat of at least one catalytic reaction.

The second reactor 3 comprises an inlet 14 and an outlet 15. The inlet 14 is intended to allow the entry of all or part of the unreacted reactants from the first reactor 2 into the second reactor 3 and/or or all or part of the products from the first reactor 2. The reactants and/or products come into contact with the second fixed bed of catalyst 11. The outlet 15 is intended to allow the products of the catalytic reaction to leave and optionally unreacted reactants outside the second reactor 3. Preferably, the inlet 12 leads to the outside of the first reactor 2 to allow reactants to be brought into the first reactor 2. Preferably, the outlet 13 opens outside the first reactor 2 to allow the outlet of the products and/or unreacted reactants out of the first reactor 2.

Advantageously, the first reactor 2 and the second reactor 3 are arranged in series. The flow of reactants and/or products circulates in the first reactor 2 then in the second reactor 3.

Preferably, the first reactor 2 corresponds to a first reaction stage while the second reactor 3 corresponds to a second reaction stage.

Advantageously, the first reactor 2 and the second reactor are fluidically connected. Preferably, the outlet 13 of the first reactor 2 is fluidly connected to the inlet 14 of the second reactor 3.

According to an advantageous embodiment, the exchanger reactor 1 comprises a fluidic connection circuit 24 ensuring the fluidic connection between the outlet 13 of the first reactor 2 and the inlet 14 of the second reactor 3. Advantageously, the connection circuit 24 is arranged at the outside of the first reactor 2. The connection circuit 24 thus makes it possible to ensure the connection in series of the first reactor 2 and of the second reactor 3 while advantageously making it possible to propose a module for processing the products and/or reagents originating from the first reactor 2 before their introduction into the second reactor 3. In addition, the presence of the connection circuit 24 makes it possible to put the first reactor 2 and the second reactor 3 in series, the two inlets 12, 14 of which are advantageously arranged opposite the outputs 13, 15. The configuration of the inputs 12,14 and the outputs 13,15 with the presence of the connection circuit 24 makes it possible to propose a co-current circulation within the reactors 2, 3. The co-current circulation makes it possible to ensure cooling of the unreacted products and/or reactants and of the reactors near their respective outlets. It is in fact preferred according to this embodiment of the invention, that at the outlet 13 of the first reactor 2, the unreacted products and/or reactants are cooled with respect to the inlet temperature in order to be advantageously treated by a processing module arranged on the connection circuit 24 to thus make it possible to shift the thermodynamic equilibrium before injecting the products and/or reagents and/or unreacted reagents into the second reactor 3 to obtain a rate improved conversion. According to the invention, the first reactor 2 and the second reactor 3 are in direct thermal contact so that the thermal energy circulates between the first reactor 2 and the second reactor 3, for example by direct conduction and advantageously without requiring the use of coolant.

According to a preferred embodiment, the second reactor 3 is arranged inside the first reactor 2. This arrangement ensures optimum compactness while allowing efficient thermal management for the catalytic synthesis.

According to one embodiment, the first reactor 2 comprises an enclosure, such as for example a tube 4, defining an interior volume. The first reactor 2 defines an interior volume receiving the second reactor 3. Advantageously, the connection circuit 24 is arranged outside the interior volume of the first reactor. The connection circuit 24 is arranged outside the enclosure. Preferably, the outlet 12 of the first reactor 2 is configured to emerge outside the interior volume defined by the first reactor 2. Preferably, the inlet of the second reactor 3 is configured to emerge outside the interior volume defined by the first reactor 2.

According to a preferred embodiment, the first reactor 2 and the second reactor 3 are fluidically connected only by the outlet 13 of the first reactor 2 and the inlet 14 of the second reactor 3.

The second reactor 3 is arranged in the reaction chamber of the first reactor 2. The second reactor 3 is arranged at least partially in direct contact with the first catalytic fixed bed 7. The direct contact ensures heat transfer between the first fixed bed and the second reactor.

Advantageously, the first reactor 2 and the second reactor 3 are concentric.

According to one possibility, the reactor-exchanger 1 can comprise a third reactor ensuring the reaction of all or part of the products and/or reactants which have not reacted in the previous reactors 2, 3. The third reactor preferably corresponds to a third reaction stage which would be arranged for example in the second reactor in the same way as the second reactor 3 is arranged in the first reactor 2, or else around the first reactor 2.

According to one embodiment, the first reactor 2 comprises a tube 4 defining an interior volume in which is arranged a first fixed bed of catalyst 7. According to one embodiment, the second reactor 3 comprises a tube 8 defining an interior volume in which is arranged a second fixed bed of catalyst 11.

The first fixed bed 7 and/or the second fixed bed 11 of catalyst is preferably a solid catalyst in powder form. For example, a finely dispersed nickel based catalyst on a porous alumina support, such as a 20% nickel on gamma alumina catalyst can be used. The catalyst can also be deposited on structures inserted in the reactive channels, it can be metallic or ceramic foams, honeycomb or fibers.

By way of example, the first reactor 2 and the second reactor 3 are made of metal. More precisely the tubes 4 and 8 are made of metal configured to be a good thermal conductor.

The tube 8 of the second reactor 3 is arranged in the internal volume of the tube 4 of the first reactor 2. Preferably, the tubes 4 and 8 are concentric. Advantageously, the tubes 4 and 8 are of circular section. The reactor-exchanger 1 thus comprises two coaxial cylinders. Tubes 4 and 8 each define a channel-shaped reaction chamber. The tubes 4, 8 each have two opposite ends. The end close to which the reagents and/or products enter is said to be proximal, while the end close to which the products and/or reagents leave is said to be distal.

The size of the tubes 4 and 8 and their length are chosen in connection with the activity of the catalyst to allow the formation of a temperature peak at the start of the first reaction stage, while limiting this peak below the temperature limit at which catalyst degradation would be too rapid.

The diameter of the first tube 4 is, for example, chosen between 15 and 50 mm and preferably between 25 and 35 mm.

The diameter of the second tube 8 is, for example, chosen between 5 and 20 mm and preferably between 10 and 15 mm.

The length of the tubes 4 and 8 is for example chosen between 100 and 500 mm and preferably between 200 and 300 mm.

Advantageously, the inlet 12 and the outlet 13 of the first reactor 2 are arranged near each end of the tube 4. Advantageously, the inlet 14 and the outlet 15 of the second reactor 3 are arranged near each end of the tube 8. In this way, the use of the length of the tubes 4, 8 is optimized. Preferably, the inlet 12 of the tube 4 of the first reactor 2 is arranged radially on the tube 4. The flow of reagents in the inlet 12 takes place in a direction radial to the tube 4, preferably perpendicular to the longitudinal axis 20 of the reactor . Preferably, in the same way, the outlet 13 of the tube 4 of the first reactor 2 is arranged radially on the tube 4. The flow of unreacted products and/or reagents in the outlet 13 takes place in a direction radial to the tube 4. According to another possibility, the inlet 12 and/or the outlet 14 can be arranged axially, that is to say the direction of the flow being parallel to the longitudinal axis 20 of the reactor.

Preferably, the inlet 14 of the tube 8 of the second reactor 3 is arranged axially on the tube 8. The flow of reagents in the inlet 14 takes place in a direction axially to the tube 8. Preferably, in the same way, the outlet 15 of the tube 8 of the second reactor 3 is arranged axially on the tube 8. The flow of products and/or unreacted reactants in the outlet 15 takes place in a direction axial to the tube 8. According to another possibility, the inlet 14 and/or outlet 15 can be arranged radially, that is to say the direction of the flow being perpendicular to the longitudinal axis 20 of the reactor.

Advantageously, the first fixed bed 7 is arranged in the annular space between the internal wall 6 of the first tube 4 and the external wall 9 of the second tube 8. Advantageously, the internal wall 6 of the first tube 4 and the external wall 9 of the second tube 8 are full. Advantageously, they are not perforated. Advantageously, they are not permeable. The first fixed bed 7 is arranged in the first reaction chamber. Advantageously, the first reactor 2 comprises two porous plugs 19 arranged in the internal volume of the tube 4 and ensuring the maintenance of the first fixed bed 7 in the tube 4. A porous plug 19 is arranged at each end of the first fixed bed 7. proximal end of the first fixed bed 7 corresponds to the inlet of the reagents and the distal end of the first fixed bed 7 corresponds to the outlet of the reagents and/or products. Advantageously, the inlet 12 of the first reactor 2 and the inlet 14 of the second reactor are arranged at the proximal end respectively of the first fixed bed 7 and of the second fixed bed 8 while the outlet 13 of the first reactor 3 and the outlet 15 of the second reactor 3 are arranged at the distal end respectively of the first fixed bed 7 and of the second fixed bed 8.

The porous plugs 19 are configured to allow the flows of reactants and/or products to pass and to prevent the passage of the fixed bed of catalyst. The porous plugs 19 can be porous structures or grids. By way of example, the streams of reactants and/or products are gas streams. Advantageously, the second fixed bed 11 is arranged in the internal volume of the second tube 8. The second fixed bed 11 is arranged in the second reaction chamber. Advantageously, the second reactor 3 comprises two porous plugs 19 arranged in the internal volume of the tube 8 and ensuring the maintenance of the second fixed bed 11 in the tube 8. A porous plug 19 is arranged at each end of the second fixed bed 11. proximal end of the second fixed bed 11 corresponds to the inlet of the reagents and the distal end of the second fixed bed 11 corresponds to the outlet of the reagents and/or products.

According to an advantageous embodiment, the proximal end of the first fixed bed 7 is offset axially relative to the proximal end of the second fixed bed 11. The proximal ends of the first and second fixed beds 7, 11 are offset along the longitudinal axis 20 of the reactor-exchanger 1. Preferably, the proximal end of the first second fixed bed 7 is more proximal than the proximal end of the second fixed bed 11. The proximal end of the first fixed bed 7 is arranged upstream of the end proximal to the second fixed bed 11.

The axial offset between the two proximal ends of the two fixed beds of catalyst 7, 11 is, for example, chosen in the range 0-100 mm and preferably in the range 10-50 mm.

Advantageously, the reactor-exchanger 1 does not include a preheating module external to the first reactor 2 or second reactor 3. In the first reactor 2 and in the second reactor 3, the reactants are advantageously introduced at room temperature. In this way, the reactor-exchanger limits energy consumption and cost by reducing the number of organs required.

The reactor-exchanger 1 advantageously comprises a heating module 16 configured to provide thermal energy to the reactor-exchanger 1. Preferably, the heating module 16 is not a heat transfer fluid. Preferably, the heating module 16 comprises a heating element such as an electrical resistor. By way of example, a heating collar is arranged at the periphery of the reactor-exchanger 1. Preferably, the heating module 16 is arranged in direct contact with the first reactor 2. More specifically, the heating module 16 is arranged in contact with the wall 5 of tube 4 of first reactor 2. Heating module 16 may comprise one or more heating elements that can be arranged along outer wall 5 of first tube 4.

According to the embodiment, corresponding to the model of Figures 4 and 5, the heating module 16 is arranged on only a portion of the first reactor 2. Preferably, the heating module 16 is arranged on a first portion 17 of the tube 4 of the first reactor. The first portion 17 is advantageously of longitudinal dimension less than that of the first fixed bed 7, only a portion 17 of the first fixed bed 7 is thus heated. By way of example, the first portion 17 represents one third of the longitudinal dimension of the first fixed bed 7. The portion of the tube 4 which does not include the heating module 16 is the second portion 18.

According to one possibility, the first portion 17 receiving the heating module 16 corresponds to the axial offset of the proximal ends of the first and second fixed beds 7, 11. The proximal end of the second fixed bed 11 is arranged at the level of the second portion 18.

Thus, the heating module heats the first portion 17 of the first tube 4 to bring the first fixed bed to a catalyst activation temperature. The reactants introduced into the first fixed bed 7 through the inlet 12 are heated by contact with the first fixed bed 7 and the reaction begins. According to one possibility, the reaction being exothermic, it releases energy in the first fixed bed 7. The flow circulating in the reaction chamber from the inlet to the outlet the temperature of the first fixed bed 7 is maintained at a temperature of activation of the catalyst on at least a portion of the tube 4 without the need to have a heating module 16 arranged all along the tube 4. Over the tube 4 in the direction of the outlet 13, the first fixed bed 7 also transfers its calories to the second fixed bed 11 which makes it possible both to heat the second fixed bed 11 and to cool the first fixed bed 7 to cool the unreacted products and/or reactants. The arrangement of the reactor-exchanger is configured to allow the progressive cooling of the first fixed bed 7 and therefore the progress of the reaction, advantageously without requiring cooling heat transfer fluid. However, the temperature must be high enough for the catalyst to be active, and higher than the condensation temperature of the water formed at the pressure of the reactor.

According to one embodiment, the distal end of the first fixed bed 7 and the distal end of the second fixed bed 11 are offset axially. The distal end of the first fixed bed 7 and the distal end of the second fixed bed 11 are offset along the longitudinal axis 20 of the reactor-exchanger 1. Preferably, the axial offset of the proximal ends and the distal ends is of the same type. Preferably, the distal end of the first fixed bed 7 is more proximal than the distal end of the second fixed bed 11. The second fixed bed 11 thus extends further downstream than the first fixed bed 7 which extends for its part further upstream. According to another embodiment illustrated for example in Figure 1, the heating module 16 comprises 3 heating elements 16a, 16b, 16c placed around the first of the tube 4. The power of each of the heating elements is regulated to control the temperature in the first fixed bed 7. The first heating element 16a is the most proximal.

By way of example, the first heating element 16a is configured to ensure a regulated temperature in the first fixed bed 7 of between 250-500°C and preferably in the range 300-360°C for the first heating element 16a.

According to a preferred possibility, the additional heating elements 16b, 16c are regulated at a temperature lower than that of the first heating element 16a to allow the progressive cooling of the first fixed bed 7 and therefore the progress of the reaction. However, the temperature must be high enough for the catalyst to be active, and higher than the condensation temperature of the water formed at the pressure of the reactor. For example in the range 150-300°C and preferably in the range 180-220°C.

The reactor-exchanger 1 comprises an insulator 26 providing thermal insulation of the reactors 2.3 so as to limit heat losses and therefore allow temperature control in the reactor-exchanger 1 without the need to use high electrical power in the heating module 16. The whole of the reactor-exchanger 1 is insulated from the outside by a rock wool or any other insulation of equivalent efficiency, more precisely, the outside of the enclosure of the reactor-exchanger, more precisely of the first reactor 2 is isolated from the outside. The insulation 26 is arranged in contact with the outer wall 5 of the tube 4 or the outer surface of the heating module 16 on the portions of the tube 4 receiving the heating module 16. The insulation 26 preferably has a thermal conductivity less than or equal to 0.05W/m/K. The thickness of the insulation 26 is preferably in the range 5-80 mm and preferably in the range 10-40 mm. The insulator 26 has for example a thickness of the order of 40mm.

According to a preferred embodiment, the exchanger reactor 1 comprises a module for processing the products and/or reagents from the first reactor 2. The processing module is advantageously arranged on the connection circuit 24 ensuring the fluidic connection between the outlet 13 of the first reactor 2 and the inlet 14 of the second reactor 3. The treatment module provides treatment for the unreacted products and/or reactants from the first reactor 2 before reintroducing at least some of these into the second reactor 3. In this way, the module treatment advantageously makes it possible to shift the thermochemical equilibrium of the reaction and make it possible to push the reaction further in the second reactor 3.

According to one possibility, an additional treatment module can be added to the outlet 14 of the second reactor 3 to treat the products and/or reactants that have not reacted at the outlet 14 of the second reactor 3.

The processing module, and possibly the additional processing module, comprises for example a condensation module 22 and advantageously a separation device 23.

The reactor-exchanger 1 according to the invention is advantageously associated with a condensation module 22 to form a reactor system.

The reactor-exchanger 1 comprises at least one condensation module comprising at least one condenser 22 arranged in fluidic connection with the outlet 13 of the first reactor 2. The condenser 22 is advantageously arranged on the fluidic connection circuit 24. According to one possibility, the reactor-exchanger 1 comprises an additional condenser arranged in fluid connection with the outlet of the second reactor 3. According to a preferred possibility, the condenser is configured to ensure passive condensation, that is to say that it is for example carried out by natural convection with air. The condenser is configured to receive a gaseous phase and supply, after condensation, a liquid phase and advantageously according to the invention a gaseous phase.

Indeed, in order to obtain a high conversion rate, it is interesting in the case of balanced reactions producing water, which is the case of hydrogenation reactions of CO or CO2, to condense this water to displace the thermodynamic equilibrium before injecting the reactants into the second reactor. This condensation advantageously takes place outside the reactor-exchanger 1. The condensation is preferably carried out by a condenser 22 using the circulation of a cold fluid or advantageously in the case of micro-methanation by natural convection with the ambient air. Advantageously, the reactor-exchanger 1 comprises at least one condenser 22. According to a preferred possibility, the reactor-exchanger 1 comprises a condenser 22a and an additional condenser 22b each respectively fluidly connected to the outlet 13 of the first reactor 2 and to the outlet 15 of the second reactor 3. The condenser(s) 22a, 22b make it possible to remove the water from the reaction before the use of the other products. Preferably, at the outlet of a condenser 22a and/or 22b, there is a liquid phase and a gaseous phase which must be separated. The reactor-exchanger 1 advantageously comprises at least one phase separation device 23. The phase separation device is advantageously arranged on the fluidic connection circuit 24 ensuring the fluidic connection of the outlet 13 of the first reactor 2 to the inlet 14 of the second reactor 3 The phase separation device 23 is advantageously configured to separate a liquid phase from a gaseous phase. The phase separation device 23 is advantageously fluidically connected to the condenser 22. Preferably, each condenser 22a, 22b is fluidically connected to a phase separation device 23a, 23b. Advantageously, the phase separation device 23 is passive. By way of example, the phase separation device 23 is an automatic purger.

Advantageously, at the outlet of the phase separation device 23, more precisely of the phase separation device 23a, the liquid phase is preferentially recycled, for example in an electrolyser conventionally used for the production of hydrogen from water while the gaseous phase is injected into the second reactor 3 by the fluidic connection circuit 24 at the level of the inlet 14 of the second reactor 3.

The reactor can be obtained by one of the methods known to those skilled in the art, for example from preformed tubes welded with addition of material or without addition of material, by brazing or even by an additive manufacturing technique. The seals can be made by joints known to those skilled in the art or by welding if subsequent dismantling is not necessary.

According to the invention, the catalyst is for example chosen to be in the solid state in powder form.

Preferably, the reactor-exchanger is configured to ensure a catalytic reaction under pressure. Preferably, the pressure in the reactor-exchanger 1, more precisely in each reactor 2, 3, is greater than atmospheric pressure. By way of example, a pressure of 5 bars, ie 5.10 ⁵ Pascal, can be implemented.

By way of example, the reactor-exchanger 1 allows the implementation of catalytic reactions for the production of methane from synthesis gas. By way of example taken in particular for the description of the present invention, the reaction is a CO ₂ methanation reaction at 5 bars, ie 5.10 ⁵ Pascals, on a 20% nickel catalyst on gamma alumina.

The main reactions during the methanation of the CO ₂ involved are: CO + 3W ₂ CW ₄ + H ₂ 0 (AH _{r 298 K} = -206.1 kJ /mol) (Rl) C0 ₂ + 4H ₂ CW ₄ + 2H ₂ O (AH _{r 298 7f} = -165.0 kJ/mol)(R2 ) C0 + H ₂ 0 C0 ₂ + H ₂ (AH _{r 298 K} = -41.2 kJ/mol) (R3) The reactions involved are then very exothermic.

Other examples of reactions can be implemented in the reactor-exchanger 1 according to the invention such as: the methanation of CO2, the methanation of CO or of a CO/CO2 mixture the reactions for the synthesis of methanol and DME the reactions of Fisher-Tropsh the wet or dry reforming of methane or other hydrocarbons

The reactor-exchanger according to the invention allows the implementation of a catalytic synthesis process.

Advantageously, the reactants are mixed beforehand before they enter the reactor-exchanger 1. The reactants, preferably mixed beforehand, enter the reactor-exchanger 1, more precisely they are introduced into the first reactor 2 through an inlet 12. Preferably, the reactants Reagents are introduced at ambient temperature into the first reactor 2. Entry into the first reactor 2 is via an inlet 12 formed for example by a radial duct, as illustrated in FIGS. 1 to 3, or axial. Advantageously, the reactants are heated for example by thermal convection with the walls, preferably metal, of at least one of the two tubes 4, 8. The reactants entering the first reactor 2 are in contact with the internal wall 6 of the first tube 4 and with the outer wall 9 of the second tube 8. The reagents then also come into contact by diffusion/dispersion with the first fixed bed 7. Preferably, by passing through the porous plug 19 proximally.

The start of the catalytic reaction in the first reactor 2 is initiated when the first fixed bed 7 is brought to a sufficient temperature. This temperature depends on the target reaction, the catalyst and the pressure. By way of example, in the case of CO2 methanation using a finely dispersed nickel-based catalyst on a porous alumina support, and if the catalyst has been correctly activated, a temperature of approximately 250°C is necessary. To reach the target temperature, according to a preferred example, a heating module 16 advantageously placed outside the first tube 4 allows the temperature rise of the first fixed bed 7 by thermal conduction. Preferably, at start-up, the power required is generated by Joule effect in the heating module 16. Then, advantageously in operation, the exothermic methanation reaction generates the heat necessary for maintaining the temperature of the first fixed bed 7. In established operation, the device consumes no or very little electricity.

Then, the reaction takes place along the first stage and the heat of reaction is evacuated mainly to the outside by natural convection, for example between the ambient air and the outer wall 5 of the first tube 4 of the first reactor 2 or between the ambient air and the outer wall of the insulation 26 or the outer wall of the heating module 16 when the reactor is equipped with it. According to one possibility, the heat of reaction is at least partially evacuated inwards by conduction, for example with the outer wall 9 of the second tube 8 of the second reactor 3.

Preferably, the reaction products and/or the unreacted reactants leave the first reactor 2 through the outlet 13 of the tube 4 after having advantageously passed through a distal porous plug 19 to exit the first fixed bed 7. Advantageously, the products of the reaction and/or the unreacted reactants emerges via the outlet 13 into the fluidic connection circuit 24.

According to one possibility, the flow leaving the first reactor 2 passes through a processing module advantageously arranged on the fluidic connection circuit 24, such as for example a condenser 22. The condenser 22 ensures the condensation, preferably passive, of the product of the reaction of so as to advantageously shift the reaction equilibrium. In the case of the methanation reaction, water is produced in the first reactor 2. By condensing the water at the outlet of the first reactor 2, the equilibrium of the reaction will be shifted to the second reactor 3.

According to a preferred possibility, the liquid phase condensed by the condenser and the non-condensed gaseous phase emerge from the condenser 22 and are separated by a separation device 23. The condensed liquid phase is evacuated to be optionally recycled in a phase of the methanation process and the gaseous phase is injected into the second reactor 3 at the level of the inlet 14 advantageously thanks to the fluidic connection circuit 24.

All or part of the products and/or reactants which have not reacted at the outlet of the first reactor 2 and which have advantageously not been condensed in the condenser 22 are reintroduced into the second reactor 3, preferably in the gaseous state.

All or part of the unreacted products and/or reactants enter, advantageously at room temperature, the second reactor 3 and only react when they come into contact with the second fixed bed 11. The second fixed bed 11 having been brought to a target catalyst activation temperature. For this, the first reactor 2 has transferred calories from the first fixed bed 7 to the second fixed bed 11. The calories coming from the heating module 16 and/or from the exothermic reaction taking place in the first reactor 2.

Then, the reaction takes place along the second stage and the heat of reaction is removed. In the last portion 27 of the second reactor 2, the reaction heat is advantageously evacuated mainly to the outside by natural convection between the ambient air and the outer wall 9 of the second tube 8 of the second reactor 3. Preferably, the reaction products and/or the unreacted reactants emerge from the second reactor 3 through the outlet 15 of the tube 8 after having advantageously passed through a distal porous plug 19 to exit the second fixed bed 11. Advantageously, the circulation of the reactants and reaction products in the first reactor 2 and in the second reactor 3 takes place in the same direction. The circulation in the first reactor 2 and in the second reactor 3 is said to be cocurrent.

A numerical simulation was carried out to size a reactor of this type for the CO ₂ methanation reaction with a nickel on alumina catalyst. The numerical model used is the one described in the article "Dynamic Modeling and Simulations of the Behavior of a Fixed-Bed Reactor-Exchanger used for CO2 Methanation" AIChE Journal, 64 (2018), it uses the reaction kinetics model described in "Carbon dioxide methanation kinetic model on a commercial Ni/Al2O3", Journal of CO2 Utilization 34 (2019), 256-265

Simulations were carried out on two reactors 2.3 of methanation reactor-exchanger 1 containing a nickel-alumina catalyst in the form of 500 μm grains and fed with a 5.10 ⁵ Pascal (5 bar) mixture of reagents of molar composition 80% H ₂ and 20% CO ₂ at 200°C. A single heating module 16 is used and its temperature is regulated at 350°C. The outward exchange coefficient is 10 W/m/K and the thermal conductivity of the insulation is 0.05 W/m/K. The walls of the tubes 4, 8 are metallic and have a thermal conductivity of 17 W/m/K.

The corresponding 2D-axisymmetric geometric model is shown in Figure 4.

The simulations are carried out for 4 flow conditions: H2 of 1, 2, 3 and 4 NL/min and CO2 of 0.25, 0.5, 0.75 and 1 NL/min, i.e. GHSV (Gas Hourly Space Velocity = volumetric velocity corresponding to the ratio of the incoming volume flow to the volume of the reactor in h-1) respectively of 750, 1510, 2270 and 3020h- 1. The velocities in the empty drum are between 1.5 and 12 cm/s leading to pressure losses of less than 100 mbar (in the simulation, the outlet pressures of two reactors 2, 3 are arbitrarily offset by 500 mbar) . The plots in Figure 6 illustrate the axial evolution at the center of each channel of each reactor 2, 3 of the temperature of the fixed bed 7, 11 and of the CO2 conversion rate, the abscissa between 0 and 0.225 m corresponding to the channel of the first reaction stage and that between 0.225 and 0.45 m corresponding to that of the second reaction stage. The conversion rate at the output of the first stage varies according to the GHSV from 96 to 97% whereas at the output of the second stage, it is close to 1 whatever the GHSV. On this same graph, the temperature profiles show a moderate temperature peak (between 425 and 550°C) for the first stage followed by a moderate gradient. Regardless of the GHSV, condensation in the channel is avoided. The maximum temperature in the second stage channel is between 300 and 400°C depending on the flow rate.

The temperature distribution in the reaction chambers, the tubes 4 and 8, the heating module 16 and the insulation 26 are illustrated in Figure 5 for a GHSV of 2270 h-1, the maximum of 512°C is obtained shortly after the proximal end in the first catalytic bed 7. The second fixed catalytic bed 11 is almost isothermal at 300° C., after a few centimeters necessary for heating the reactants.

Figure 6 shows the evolution of the temperature in the center of the first bed 7, 4 cm from the proximal end of the first fixed bed 7 as a function of time for different heating powers. According to this simulation, for a power of only 150 W, less than 10 minutes are needed to restart the reactor after a complete shutdown. The proposed architecture also allows rapid start-up of the reactor-exchanger in the event of a shutdown caused, for example, by a hydrogen supply shutdown following, for example, a shutdown in electricity production in the absence of sun or wind.

This optimization ensures that the reactor-exchanger according to the invention is suitable for small installations typically of the order of 0.25 to 1 Nm3/h of converted hydrogen. The exchanger reactor can be used for the production of decentralized fuels from renewable energy, on the scale of an isolated site such as an agricultural site, a community, an isolated living base.

In these configurations, the renewable energy generally comes from photovoltaic solar modules or a wind turbine and is therefore intermittent and limited in quantity. The low thermal inertia of the reactor-exchanger according to the invention generates significant start-up and shutdown times compatible with the intermittency of production.

The reactor dimensioned here makes it possible to treat reagent flow rates of 1.25 Nm3/h and to have a conversion to methane close to 1 allowing the direct use of the methane generated after the water produced has been removed. The treatment of higher flow rates, for example of the order of 3 to 5 Nm3/h can be done using the same principle, but by increasing the diameter of the first tube 4, which proportionally increases the exchange surface. To maintain an equivalent GHSV, the diameter of the second tube 8 is increased in proportion, possibly a third tube is arranged in the second tube 8 to limit the volume of the catalytic bed of the second reactor.

Alternatively, this variant can be implemented without adding this third tube, the volume of the catalytic bed of the second reactor 3 will be increased, the overall GHSV will be reduced, but the second reactor 3 being not very exothermic, this solution remains effective.

The invention is not limited to the embodiments previously described and extends to all the embodiments covered by the claims.

LIST OF REFERENCES

1. Reactor-exchanger

2. First reactor

3. Second reactor

4. Tube of the first reactor

5. Outer wall of the first reactor

6. Inner wall of the first reactor

7. First Fixed Catalyst Bed

8. Second reactor tube

9. Outer wall of the second reactor

10. Inner wall of the second reactor

11. Second Fixed Catalyst Bed

12. Entrance to the first reactor

13. Exit of the first reactor

14. Entrance to the second reactor

15. Exit from the second reactor

16. Heating module

17. First Serving

18. Second Serving

19. Porous plug

20. Longitudinal axis

21. First Reactor Center

22. Condenser

22a. Condenser

22b. Condenser

23. Phase separator

2a. Phase separator

23b. Phase separator

24. Fluid connection

25. Upstream section

26. Insulation

27. Last portion of the second reactor

28. Axial offset of the proximal ends of the fixed beds.

101. 50W heating power. 8 102. 100W heating power. 8

103. 150W heating power. 8

104. 200W heating power. 8

105. 250W heating power. 8

106. Ignition temperature

1001. Temperature at the center of the first fixed bed for a GHSV of 750 h' ¹

1002. Temperature at the center of the first fixed bed for a GHSV of 1510 h' ¹

1003. Temperature at the center of the first fixed bed for a GHSV of 2270 h' ¹

1004. Temperature at the center of the first fixed bed for a GHSV of 3020 h' ¹

1011. Conversion rate at the center of the first fixed bed for a GHSV of 750 h' ¹

1012. Conversion rate at the center of the first fixed bed for a GHSV of 1510 h' ¹

1013. Conversion rate at the center of the first fixed bed for a GHSV of 2270 h' ¹

1014. Conversion rate at the center of the first fixed bed for a GHSV of 3020 h' ¹ 2001. Temperature at the center of the second fixed bed for a GHSV of 750

2002. Temperature at the center of the second fixed bed for a GHSV of 1510 h' ¹

2003. Temperature at the center of the second fixed bed for a GHSV of 2270 h' ¹

2004. Temperature at the center of the second fixed bed for a GHSV of 3020 ^h'1

2011. Conversion rate at the center of the second fixed bed for a GHSV of 750 h' ¹

2012. Conversion rate at the center of the second fixed bed for a GHSV of 1510 h' ¹

2013. Conversion rate at the center of the second fixed bed for a GHSV of 2270 ^h'1

2014. Conversion rate at the center of the second fixed bed for a GHSV of 3020 ^h'1

Claims

25 CLAIMS

1. Catalytic synthesis reactor-exchanger (1) comprising a first reactor (2) capable of receiving a first fixed bed (7) of catalyst, and a second reactor (3) capable of receiving a second fixed bed (11) of catalyst , the first reactor (2) and the second reactor (3) being arranged in series, characterized in that the second reactor (3) is arranged inside the first reactor (2) so that the second reactor (3) or in contact with the first fixed bed (7) of catalyst of the first reactor (2) to ensure heat exchange between the first reactor (2) and the second reactor (3) without the need for heat transfer fluid.

2. Reactor-exchanger (1) for catalytic synthesis according to the preceding claim comprising a connection circuit (24) configured to ensure the fluidic connection of the first reactor (2) to the second reactor (3), the connection circuit (24) being arranged outside the first reactor.

3. Reactor-exchanger (1) for catalytic synthesis according to the preceding claim wherein the first reactor (2) comprises an inlet (12) configured to ensure the entry of reactants into the first reactor (2) and an outlet (13) configured to provide exit of unreacted products and/or reactants from the first reactor (2), and the second reactor (3) comprises an inlet (14) configured to provide entry into the second reactor (3) of all or part of unreacted reactants and/or reactants from the first reactor (2) and/or products from the first reactor (2) and an outlet (15) of products and/or reactants not having not reacted outside the second reactor (3), the outlet (13) of the first reactor (2) is fluidically connected to the inlet (14) of the second reactor (3) by the connection circuit.

4. Reactor-exchanger (1) for catalytic synthesis according to the preceding claim wherein the inlet (12) of the first reactor (2) and the inlet (14) of the second reactor (3) are arranged at a first end, respectively of the first reactor (2) and of the second reactor (3), the outlet (13) of the first reactor (2) and the outlet (15) of the second reactor (3) are arranged at a second end, respectively of the first reactor (2 ) and the second reactor (3) opposite the first end.

5. Catalytic synthesis reactor-exchanger (1) according to any one of the preceding claims, in which the second reactor (3) and the first reactor (2) are concentric.

6. Catalytic synthesis reactor-exchanger (1) according to any one of the preceding claims, in which the first reactor (2) comprises a first tube (4) defining an interior volume configured to receive the second reactor (3) and the first fixed bed (7) of catalyst.

7. Reactor-exchanger (1) for catalytic synthesis according to the preceding claim wherein the first reactor (2) comprises an inlet (12) configured to ensure the entry of reactants into the first reactor (2) and an outlet (13) configured to ensure the exit of unreacted products and/or reagents from the first reactor (2), the inlet (12) and the outlet (13) being arranged radially on the first tube (4).

8. Catalytic synthesis reactor-exchanger (1) according to any one of the preceding claims, in which the second reactor (3) comprises a second tube (8) arranged in the internal volume of the first reactor (2) and defining an internal volume configured to receive the second fixed bed (11) of catalyst.

9. Reactor-exchanger (1) for catalytic synthesis according to the preceding claim wherein the second reactor (3) comprises an inlet (14) configured to ensure the entry into the second reactor of all or part of reagents and / or unreacted reactants from the first reactor (2) and/or products from the first reactor (2) and an outlet (15) of unreacted products and/or reactants from the second reactor (3), the inlet (14) and the outlet (15) being arranged radially or axially on the second tube (8).

10. Reactor-exchanger (1) for catalytic synthesis according to claims 4 and 6 wherein a proximal end of the first fixed bed (7) of catalyst arranged opposite the inlet (12) of the first reactor (2) is offset along the longitudinal axis (20) of the first reactor (2) with respect to a proximal end of the second fixed bed (11) of catalyst arranged facing the inlet (14) of the second reactor (3).

11. Catalytic synthesis reactor-exchanger (1) according to the preceding claim, in which the proximal end of the first fixed bed (7) is arranged upstream of the proximal end of the second fixed bed (11).

12. Reactor-exchanger (1) for catalytic synthesis according to any one of the preceding claims comprising a heating module (16) arranged in direct contact with the outside of the first reactor (2).

13. Reactor-exchanger (1) for catalytic synthesis according to the preceding claim in combination with claim 3 wherein the heating module (16) is arranged on a first portion (17) of the first tube (4) of the first reactor (2) of dimension less than the total length of the first tube (4) of the first reactor (2).

14. Reactor - exchanger (1) for catalytic synthesis according to any one of the preceding claims in combination with claim 2 comprising a processing module arranged at the output of the first reactor (2) on the connection circuit (24) configured to ensure treatment of unreacted products and/or reactants at the outlet of the first reactor (2) before their introduction into the second reactor (3).

15. Reactor-exchanger (1) for catalytic synthesis according to any one of the preceding claims comprising a condensation module (22a) arranged at the outlet of the first reactor (2) configured to ensure the condensation of water produced in the first reactor ( 2).

16. Reactor-exchanger (1) for catalytic synthesis according to the preceding claim comprising a phase separation device (23a) arranged at the outlet of the condensation module (22) configured to separate the liquid phase from the gaseous phase intended to be reintroduced into the second reactor (3).

17. Catalytic synthesis process in an exchanger reactor (1) for catalytic synthesis according to any one of the preceding claims comprising:

• Injection of reagents into a first reactor (2) through an inlet (12)

• The reaction of the reactants in the first fixed bed (7) of catalyst,

• The output of unreacted products and/or reagents via an output (15) out of the first reactor (2),

• Injection of all or part of unreacted reactants and/or products and/or reactants from the first reactor (2) into the second reactor (3) through an inlet (14),

• The reaction of the reactants in the second fixed bed (11) of catalyst

• The outlet of the unreacted products and/or reagents out of the second reactor (3) via an outlet (15).

18. Method according to the preceding claim comprising the heating of a first portion (17) of the first reactor (2) by a heating module (16), 28

19. Process according to any one of the two preceding claims comprising the circulation of the products and/or of the unreacted reactants in the first reactor (2) and in the second reactor (3) in co-current.

20. Process according to any one of the three preceding claims, comprising the circulation of the products and/or of the unreacted reactants coming from the first reactor (2) in a connection circuit (24) arranged outside the first reactor. (2) and fluidly connected to the inlet (14) the second reactor (3).

21. Method according to any one of the four preceding claims comprising the condensation of the products from the first reactor (2) before injection into the second reactor (3) by a condensation module (22a).

22. Method according to the preceding claim comprising the separation of a liquid phase and a gas phase after condensation and before the injection of the gas phase into the second reactor (3) by a phase separation device (23a).