Microreactor for carrying out continuous chemical methods involving solids

Abstract

The present invention relates to a continuous chemical reactor comprising an one-piece part (10) that has a plurality of through-channels (100, 200), each of said channels allowing a fluid to flow through the one-piece part; and a source for subjecting the part to an ultrasonic wave (ultrasound).

Description

^^ Microreactor for the implementation of continuous chemistry processes involving solids

[0001] The present invention relates to the field of continuous microreactor chemistry. It relates more specifically to the particular field of continuous microreactor chemistry processes where solids are introduced and / or formed in the microreactor.

[0002] The term "continuous chemistry", synonymous with the more complete expression "continuous flow chemistry", designates a particular mode of implementation of a chemical reaction (reaction of one or more reactants leading to one or more ^^^ products distinct from the reactants) and / or physical (for example crystallization or precipitation) where the reaction medium is put into flow within a reactor, whereby the reaction takes place progressively along the flow, which schematically makes it possible to convert spatially along the flow the temporal evolution observed in a classic batch reactor of the ^^^ balloon type.

[0003] The present invention relates to continuous chemistry reactions of this type which are carried out within small-sized reactors, designated by the generic term "microreactors". As used in the present description, a "microreactor" designates a device for continuous chemistry, which ^^^ comprises at least one channel where the physical and / or chemical reaction takes place and where this channel has a cross-section of dimensions less than 20 mm, typically less than or equal to 10 mm. The overall dimensions of the area of ​​a continuous chemistry microreactor where the reaction takes place are generally less than 1 m, most often less than or equal to 50 cm and typically ^^^ less than or equal to 30 cm.

[0004] Continuous chemistry in microreactors is a booming field, as it allows chemical reactions to be carried out safely, even under difficult conditions, while minimizing the reaction volume.

[0005] In addition, continuous chemistry in a microreactor allows precise control of the temperature of the medium, even in the case of highly exothermic or endothermic reactions, thanks to the surface area to volume ratio which is very favorable to the heat exchange that a microreactor allows. ^^

[0006] The use of microreactors also makes it possible to carry out reactions involving high pressure under enhanced safety conditions. The use of microreactors is, for example, an advantage for implementing hydrogenation reactions, which present much lower risks with smaller reactors.

[0007] Continuous microreactor chemistry is also well-suited to the use of toxic or hazardous gases, limiting the quantities to which an operator and the environment are potentially exposed. This makes continuous microreactor chemistry well-suited to the production of phosgene, for example. ^^^

[0008] Another advantage of continuous chemistry in microreactors is its environmental friendliness: it allows for the minimization of solvent use and the reduction of the formation of co-products or impurities, which are generally destroyed by incineration.

[0009] That being said, a problem encountered when implementing continuous chemistry in a microreactor is the presence of solids. Most of the microreactors currently known are unsuitable for implementing chemical reactions using solids (e.g., reagents or catalysts) or generating solids (solid products or by-products, precipitates, crystals, etc.), which tend to block all or part of the small-section channels used in microreactors, hindering the flow and thus disrupting the reaction conditions and its control possibilities, or even completely clogging the microreactor and quickly rendering it unusable.

[0010] This problem is far from negligible when we know that many organic chemistry reactions of industrial interest that can be carried out continuously generate solids (63% of organic chemistry reactions of industrial interest if we refer to RL Hartman, Organic Process Research & Development, 2012, 16, 870-887). The provision of microreactors capable of managing the presence of solids would therefore make it possible to multiply by a factor of 3 the use of continuous chemistry at the industrial level. ^^^

[0011] Different solutions have been proposed to try to manage the presence of solids in continuously conducted reactions. ^^

[0012] In this context, the approach currently experiencing the most significant commercial developments is the development of continuous stirred reactors. Although it leads to interesting results, this approach is not suitable for chemical reactions requiring a uniform residence time for the entire reactant flow, which is often necessary to avoid the formation of co-products. In addition, the temperature and pressure range that can be used in a stirred reactor is limited, which restricts the possibilities for intensification of processes using continuous stirred reactors.

[0013] Apart from this approach, the use of ultrasonic waves (ultrasound) has been described to manage solids and prevent clogging in reactors, but the solutions proposed in this context prove to be poorly suited to industrial implementation: - Application WO 2011 / 023761 describes a method for preventing clogging within a reactor by immersing an ultrasonic source in the liquid conduit of the reactor, which allows the propagation of ultrasound along the channel. A miniature ultrasonic source intended for this type of application is described, for example, in application CN 210876549. - Another approach, described in patent application US 2021 / 197168-A1, consists of immersing a coil, generally metallic, in a liquid medium, generally water, in which an ultrasonic source is immersed.In this case, the ultrasound is first propagated to the liquid medium then to the walls of the coil and finally to the reaction medium which flows in the coil. - Plate reactors have also been described, in particular in CN 208320769 or CN215087044, which are placed in contact with an ultrasonic source. This type of plate tank consists of a stack of etched plates screwed together, these etchings forming channels once the plates are stacked. - according to yet another approach, described for example in CN114100530 or CN112403417, a shell-and-tube type exchanger reactor is used, which comprises internal tubes which are set into vibration under the effect of an ultrasonic wave which induces their oscillation.

[0014] The implementation of ultrasonic waves, although it has been the subject of numerous publications, has not yet found any industrial outlets. ^^ concrete, and this for different reasons, each of which constitutes an obstacle to the development of this technology.

[0015] A first major reason lies in the fact that it is well known that ultrasound is likely to damage the structure of the reactors in which it is applied.

[0016] Furthermore, although the use of ultrasound appears attractive in absolute terms, it turns out in practice that the propagation of ultrasound is difficult to control in the heterogeneous media described in the aforementioned documents. In particular, the plate reactors and calender reactors of the aforementioned documents constitute highly heterogeneous media where the application of ultrasound cannot be carried out homogeneously. This difficulty is all the more troublesome since locally excessive and / or poorly controlled ultrasound power can lead to the formation of free radicals within the reaction medium, which are likely to cause parasitic reactions, which can negatively impact the purity of the production and / or induce risks detrimental to the safety of the process.

[0017] An aim of the present invention is to provide a device allowing continuous chemistry to be implemented in a microreactor in the presence of solids, but avoiding the aforementioned drawbacks. ^^^

[0018] To this end, the invention proposes a new type of microreactor implementing a particular application of ultrasonic waves (ultrasound), which in particular makes it possible to avoid the disadvantages of the plate reactors and calender reactors of documents CN 208320769, CN215087044, CN114100530 or CN112403417, and the inventors of which have further demonstrated that it allows ^^^ an efficient and homogeneous, and therefore finely controllable, propagation of the ultrasonic waves throughout the structure of the reactor.

[0019] More specifically, according to a first aspect, the present invention relates to a reactor for continuous chemistry, comprising: - a single-piece part provided with several through channels, each of said ^^^ channels allowing the flow of a fluid through said single-piece part; and ^^ - an ultrasonic source allowing the single-piece metal part to be subjected to an ultrasonic wave.

[0020] In the microreactor of the invention, the through channels are most often placed in fluid connection with each other to form at least two separate circuits (100; 200), each allowing separate circulation of fluid.

[0021] The single-piece part of the microreactor of the invention is a single-piece part, which comprises the aforementioned through channels, each of which makes it possible to contain a fluid and to convey a flow of this fluid through the part. Within this single-piece part, the volume occupied by the through channels represents ^^^ typically less than 50% and most often less than 40%, or even less than 20% of the total volume of said single-piece part. In other words, the single-piece part used according to the invention is a part whose internal space is mainly (and preferably essentially) occupied by material rather than by voids. ^^^

[0022] A single-piece part of this type has a first advantage, namely significant robustness which minimizes (or even eliminates) the risks of seeing the part damaged by the effect of the ultrasonic wave.

[0023] Furthermore, the implementation of a single-piece part of the aforementioned type allows optimized propagation of the ultrasonic waves within the part and in the ^^^ channels, which constitutes another advantage of the invention.

[0024] In particular, to further enhance this homogeneity of the application of ultrasonic waves, it is preferable for the single-piece part to be a part formed from a single material having a homogeneous composition throughout the single-piece part, generally a single metal or a single metal alloy. Furthermore, it is preferable for the through channels to be distributed homogeneously in the single-piece part. .

[0025] The reactor of the invention proves to be superior to the plate and calender reactors proposed in the state of the art not only due to its increased robustness, but also due to the homogeneous propagation of the ultrasonic waves that it allows. Such homogeneity is not obtained with plate and calender reactors, in particular because they require the use of several parts (several plates for plate reactors; several tubes ^^ internal for calendrical reactors) and therefore numerous heterogeneous interfaces between these parts to ensure the role that the single-piece part of the invention alone ensures, free of such interfaces. It should be noted in this regard that the channels present in the single-piece metal part according to the invention are ^^ through channels, namely emerging channels which are therefore provided with at least one inlet allowing fluid to be introduced into the part and at least one outlet allowing fluid to be evacuated from the part. These channels are therefore located within the single-piece part, which distinguishes them in particular from the grooves present on the surface of the plates of plate reactors. On the other hand, the ^^^ single-piece metal part of the invention is distinguished from each of the internal tubes of calendrical reactors by the presence of several channels.

[0026] As indicated, the through channels present in the single-piece part of a reactor according to the invention are advantageously placed in fluid connection with each other to form at least two separate circuits, each allowing a separate circulation of ^^^ fluid. These separate circuits involve a first part of the channels for the first circuit and another separate part of the channels for the second circuit. These separate circuits formed by the channels in fluid connection may for example comprise at least a first circuit allowing a circulation of a reaction medium and at least a second circuit allowing a circulation of a ^^^ fluid ensuring thermal regulation. Within a given circuit, the channels may be connected in series, in parallel or in mixed series and parallel mode.

[0027] By way of illustration, a channel circuit intended to convey a reaction medium may, for example, comprise several inlets corresponding to the inlet of one or more of the channels of the single-piece part, the outlets of which are placed in ^^^ fluid connection, which allows the introduction of different fluids into the part and then their mixing, which may, for example, be used to introduce reactants separately, or a flow of reactants and a flow comprising an activator or a catalyst). Alternatively, a channel circuit intended to convey a reaction medium may more simply comprise a single inlet ^^^ and consist, for example, of several channels of the single-piece part connected together in series (for example in the case of a crystallization reaction or any other type of reaction not necessarily involving the introduction of separate fluids). ^^

[0028] A channel circuit intended to convey a fluid ensuring thermal regulation preferably comprises channels of the single-piece part in parallel, namely channels having inlets in fluid connection (and generally outlets in fluid connection), which makes it possible to convey in the part the same ^^ thermal regulation fluid brought to the same inlet temperature.

[0029] The establishment of a fluid connection between an outlet of one of the channels of the single-piece part with the inlet of another of the channels can be carried out by any means known per se. Taking into account the application of ultrasonic waves, it is however preferable to use connection means whose integrity is not affected by these waves. According to an interesting embodiment, the single-piece part comprises, for a given fluid circuit, two parallel faces where all the inlets and all the outlets of the channels involved in said circuit open; and the reactor comprises two caps held in abutment respectively on one and the other of these parallel faces, each of the caps comprising connecting tubes whose openings open onto the surface abutting one of said parallel faces of the single-piece part, opposite two openings (one inlet and one outlet) of two channels opening onto said face.The implementation of caps of this type makes it possible to easily modulate the nature of the circuits produced from the single-piece part, in particular to adapt the desired ^^^ residence times, which constitutes another advantage of the invention. According to another possible embodiment of the invention, all the fluid circuits operate exclusively within the single-piece part with all the channels present in the structure of the single-piece part. A single-piece microreactor of this type hollowed out with a more or less complex network of channels is particularly ^^^ subject to fouling and would therefore not be conceivable outside the particular context of the invention.

[0030] The ultrasonic source used according to the invention may be any device delivering an ultrasonic wave, namely a mechanical wave (also called "ultrasound") capable in particular of propagating within the single-piece part and ^^^ fluids contained in the channels and whose frequency is typically greater than 16 kHz, for example between 16 and 100 kHz, more advantageously between 18 kHz and 50 kHz. The invention involves the application of at least one wave of this type from the source, or a superposition of several waves of this type. ^^ type, continuously or not. Thus, when the present description refers to the application of an ultrasonic wave it is intended to cover both the application of a single wave of this type as well as several, simultaneously or successively. Typically, the ultrasonic source implemented according to ^^ the invention to provide such an ultrasonic wave is a piezoelectric generator (which typically uses a piezoelectric ceramic).

[0031] Whatever its exact nature, the ultrasonic source used according to the invention is preferably mechanically linked to the aforementioned single-piece metal part, and, even more advantageously, it is preferable for it to be mechanically secured to the single-piece metal part, for example by screwing onto a threaded rod made from the same material or welded to the body of said part, or by screwing onto the metal part by means of a stud screwed on one side to the single-piece metal part and on the other to the ultrasonic source. . This mechanical connection, associated with the monobloc nature of the part comprising the channels used according to the invention, allows efficient propagation of the ultrasonic waves throughout the structure of the monobloc part, and therefore throughout the entire through channels, with much lower attenuation of the wave than in plate reactors or calendered reactors.

[0032] These different advantages make it possible to use ultrasonic waves for two purposes in a reactor according to the invention when it is used for a physical and / or chemical reaction involving solids.

[0033] For the purposes of this description, a “physical and / or chemical reaction involving solids” is typically a physical and / or chemical reaction in which: ^^^ (i) solids are introduced upstream of the reaction, which are for example solid reactants, solid catalysts and / or other solid additives; and / or (ii) solids are formed by the reaction (precipitates, insoluble reaction products, etc.)

[0034] When solids are formed by the reaction, they are found dispersed ^^^ in the reaction medium conveyed in the reactor. Similarly, when solids are introduced upstream of the reaction according to the invention, they are preferably all in dispersion in the reaction medium circulating in the reactor. ^^ preferably, the reaction does not use reagents, catalysts or additives which would be undispersed solids. In particular, according to a preferred embodiment, the reaction carried out in a reactor according to the invention does not use solids deliberately immobilized on the wall of the reactor, ^^ such as for example catalysts coated on the walls of the reactor as described in application EP 3241612.

[0035] According to a first possibility, ultrasonic waves can be used as a preventative measure in a reactor according to the invention where a reaction involving solids takes place, namely to avoid the formation of solid deposits within the through channels, which otherwise induces a loss of performance of the reactor, or even renders it unusable in the event of total clogging.

[0036] More specifically, a particular subject of the present invention is a method for limiting the formation of solid deposits within the through channels of a continuous chemistry reactor of the aforementioned type, comprising: ^^^ - at least one step (e) of physical and / or chemical reaction carried out within at least a portion of said through channels, where said reaction is carried out in the presence of a solid introduced upstream of said channels; and / or said reaction leads, within the through channels, to the formation of a solid, and - at least one step (e1) of applying an ultrasonic wave to the single-piece part ^^^ from the ultrasonic source during said step (e).

[0037] The application of ultrasonic waves of step (e1) can advantageously be carried out continuously throughout the duration of step (e). To do this, the application of ultrasonic waves can be carried out in continuous mode throughout the entirety of step (e). According to another possible alternative, the application of the ultrasonic wave ^^^ can be carried out in pulsed mode, namely by cyclically alternating short periods (typically ranging from 10 ms to 2 seconds) of application of ultrasonic waves, followed by short periods (typically from 200 ms to 5 seconds) without application of ultrasonic waves (called "white periods"). ^^^

[0038] According to another possibility (compatible if necessary with the previous possibility using the ultrasonic wave as a preventive measure), the application of the ultrasonic wave can be used as a “curative” measure in a reactor according to the invention where the ^^^ previously a reaction involving solids, namely to eliminate in whole or in part a solid deposit which has formed within the through channels during said reaction. In this context, the work of the inventors has now made it possible to demonstrate that, surprisingly, this elimination proves to be ^^ particularly effective by using a microreactor according to the invention, where the application of the ultrasonic wave proves to lead to a substantial - if not total - elimination of the solid deposits, as illustrated by the examples given at the end of this description.

[0039] In other words, another object of the present invention is a method ^^^ for removing a solid deposit formed within the through channels of a microreactor of the aforementioned type, comprising: - at least one step (e) of physical and / or chemical reaction carried out within at least a portion of said through channels, where said reaction is carried out in the presence of a solid introduced upstream of said channels; and / or said reaction ^^^ leads, within the through channels, to the formation of a solid, and where a solid deposit is formed during step (e); and - at least one step (e2) of applying an ultrasonic wave to the single-piece part from the ultrasonic source after said step (e).

[0040] According to one embodiment, the reaction is stopped at the end of step (e), then ^^^ the single-piece part is subjected to the ultrasonic wave during step (e2).

[0041] According to an alternative embodiment, step (e2) may take place after the formation of a solid deposit has taken place in step (e), but without stopping the reaction. In this case, the physicochemical reaction takes place not only in step (e), where the solid deposit is formed, but also during step (e2), during which the ultrasonic wave is applied to remove this deposit while continuing the reaction. In other words, according to this alternative embodiment, the method comprises the following steps: - at least one step (e) of physical and / or chemical reaction carried out within at least a portion of said through channels, where said reaction is carried out in the presence of a solid introduced upstream of said channels; and / or said reaction leads, within the through channels, to the formation of a solid, and where a solid deposit is formed during step (e); and - at least one step (e2) of applying an ultrasonic wave to the single-piece part ^^^ from the ultrasonic source after said step (e), by continuing the reaction of step (e). When this method is implemented, it is possible, if necessary, during step (e2), to divert part of the reaction medium if it is desired to avoid its contamination by the solid released during step (e2). Like step (e1) described ^^ above, step (e2) can be carried out in continuous mode or in pulsed mode, preferably under the conditions described for step (e1), regardless of the variant envisaged.

[0042] Although the joint and successive implementation of steps (e1) and (e2) is not excluded according to the invention, step (e2) is especially of interest when ^^^ step (e1) is not used. In this case, step (e2) is most often implemented only when a solid deposit occurs, which induces total or complete clogging, detectable in particular by an increase in the pressure drop in the reactor. Step (e2) proves to be particularly effective and allows elimination of the solid deposit and a return to the nominal pressure drop of the reactor ^^^ after very short application times of the ultrasonic wave, namely typically between 1 and 10 minutes and most often less than 3 minutes.This possibility of very rapid and efficient post-treatment of solid deposits, which requires an almost negligible intervention time in the event of clogging, constitutes another very interesting advantage of the method of the invention, which therefore allows, if necessary, the possibility of completely dispensing with the preventive mode (namely the possibility of not implementing step (e1) at all), which has a direct positive impact on process costs. In particular, the curative treatment according to the invention can be applied by only immobilizing the production tool for very short periods (much shorter than that of a dismantling and cleaning intervention of the conduits on devices of the state of the art, when such a dismantling and cleaning intervention proves possible, which is not always the case with currently known devices where the fouling can prove irreversible).

[0043] Various particular aspects of the invention as well as possible embodiments are described in more detail below.

[0044] The single-piece part and the channels that run through it ^^^

[0045] The single-piece part of the microreactor of the invention is preferably made of a single metal or metal alloy, which is preferably chosen from: - steels and in particular stainless steels such as 316 L steel; - nickel-based alloys such as the alloys sold under the ^^ brands Hastelloy, Monel, Inconel, Incoloy, Nimonic, or Nilo; - tantalum; - titanium and its alloys, in particular TA6V; - aluminum and its alloys; - copper and its alloys; ^^^ - nickel.

[0046] Furthermore, the single-piece part of the microreactor of the invention comprises through channels which can be formed by any means known per se. These channels can, in absolute terms, be of any shape, for example prismatic or cylindrical (with circular or polyhedral cross-sections, for example square or rectangular). The single-piece part of a reactor of the invention can in particular be produced by machining a single-piece initially not provided with channels; by 3D printing; or even by assembly and diffusion welding of several parts, to ultimately form a single part of a single block whose mechanical properties are at least as high as those of the constituent parts and whose integrity is not compromised by the application of an ultrasonic wave.

[0047] The one-piece part comprises several such channels, generally at least two and preferably much more than two, typically between 4 and 15,000, typically between 10 and 10,000. ^^^

[0048] These channels have a cross-section whose dimensions are preferably less than or equal to 20 mm, and preferably less than or equal to 10 mm, for example less than or equal to 8 mm, and in particular less than or equal to 6 mm.

[0049] Thus, for a given channel present within the single-piece part, the cross-section ^^^ of said channel perpendicular to the longitudinal axis of this channel forms a closed curve (for example a circle or a polyhedron) which preferably has at least one of the following properties: ^^^ - this curve (the section of the internal wall of the channel) can be entirely included in a circle with a diameter of less than 20 mm, preferably less than or equal to 10 mm, for example less than or equal to 8 mm, in particular less than or equal to 6 mm; and / or ^^ - the maximum distance between two points of the curve (namely what is commonly called "the largest dimension of the section", for example the diameter for a circle or the diagonal for a square) is less than 20 mm, preferably less than or equal to the aforementioned dimensions, this distance typically remaining greater than or equal to 1 mm, for example between 1 and 20 mm, ^^^ in particular between 2 mm and 10 mm.

[0050] At least a portion of the through channels present in the single-piece part is intended to convey the reaction medium where the reaction of which the reactor is the seat takes place, typically the reaction medium of step (e). The channels conveying the reaction medium (with injected solids or during the reaction) preferably have a cross-section forming a curve without an angle (typically a circular section), to facilitate the circulation of solid particles and to avoid the accumulation of solids. These channels are typically cylinders of circular section with a diameter of between 2 mm and 25 mm, advantageously between 3 and 12 mm, and preferably between 4 and 8 mm. ^^^

[0051] The length of each of the through channels present in the single-piece part intended to convey the reaction medium is generally between 10 and 1000 mm, preferably between 50 and 600 mm, more preferably between 100 and 500 mm.

[0052] The single-piece part of the reactor of the invention is advantageously provided with at least two channels intended to convey the reaction medium, and preferably between 3 and 10,000 channels, for example between 4 and 1,000.

[0053] In addition to the aforementioned channels intended to convey a reaction medium, it is generally advantageous for a portion of the through channels to be intended to convey a fluid ensuring thermal regulation of the reaction taking place in the reactor. The reactor of the invention is in fact particularly advantageous for implementing exothermic or endothermic reactions where regulation of this type is necessary. By virtue of its design, the reactor ^^^ of the present invention allows excellent thermal regulation. In particular to optimize thermal regulation, the channels used to convey the fluid intended to ensure thermal regulation are preferably channels of polyhedral section, advantageously rectangular, which makes it possible to maximize ^^ thermal exchanges. The cross section of these channels is advantageously a rectangle, each of whose sides has a length ranging from 1 to 10 mm, for example from 1 to 6 mm, in particular from 1 to 4 mm

[0054] The single-piece part of the reactor of the invention may, for example, comprise both channels for thermal regulation and channels for the passage of the reactants with a ratio of the number of channels for thermal regulation to the number of channels for the passage of the reactants of between 5:1 and 25:1, preferably between 10:1 and 18:1.

[0055] The total volume of the single-piece part of a reactor according to the invention, hereinafter referred to as VT, can be subdivided into: (1) the cumulative volume of the internal space ^^^ of the channels intended to convey a reaction medium, called VR; (2) the cumulative volume of the internal space of the channels intended to convey a heat transfer fluid, called VU; and (3) the volume of the rest of the part (namely of the material constituting the part, outside the voids forming the channels), called VR, with VT=VR+VU+VM.

[0056] It is generally preferable that the VM / VT ratio is between 50% and ^^^ 99.5%, preferably 60 and 99%, preferably 80 and 98%, preferably between 90 and 97%

[0057] Furthermore, it is preferred that the part be provided with both types of channels (intended to convey a reaction medium; and intended to convey a heat transfer fluid) with a VR / VU ratio of between 4:1 and 1:4, preferably between 2:1 and 1:2. ^^^

[0058] Generation of the ultrasonic source wave

[0059] The frequencies of the ultrasonic waves used in the context of the present invention and generated by the ultrasonic source are preferably between 18 and 50 KHz, preferably between 20 and 35 KHz. These are thus most often waves belonging to the category known as low-frequency power ultrasounds.

[0060] According to a particular reaction mode, the frequency of the ultrasonic wave used according to the invention is a frequency corresponding to a resonance mode ^^^ of the single-piece part of the reactor. However, this mode is completely optional and it can be considered conversely not to use an ultrasonic wave of this type to avoid the reactor entering resonance.

[0061] The total power of the ultrasonic wave(s) applied according to the invention, in particular during the aforementioned steps (e1) and / or (e2), is preferably between 10 and 300 W per liter of reactor, preferably between 20 and 100 W per liter of reactor, the reactor volume in liters referred to here being the total volume (VT) of the reactor defined above in the present description.

[0062] The physical reaction implemented in the reactor of the invention. ^^^

[0063] The reactor of the present invention can in particular be used for all chemical reactions inducing the formation of solids, as a reaction product and / or as a co-product. It is also of interest for the implementation of chemical reactions initially involving the injection of a reactant in solid form or the introduction of solids for another reason ^^^ (catalyst or activator for example or solids present in the reaction medium treated for other reasons, for example a filler or a support).

[0064] The chemical reactions that can be carried out in the reactor of the invention include organic chemistry reactions such as Boc protection, borylation reactions generating lithium borate, carbon-carbon coupling reactions such as Suzuki coupling or Suzuki-Miyaura coupling, carbon-nitrogen coupling reactions such as amination or aldol condensation, reactions involving organometallic compounds such as the Grignard reaction or oxidation reactions using potassium permanganate as the oxidizing agent.

[0065] These can also be chemical reactions involving heterogeneous catalysts in a moving bed, or the solid catalyst is introduced into the reactor in the form of slurry and is conveyed into the reactive channels with the other reactants. Reactions involving this type of heterogeneous catalyst in a moving bed are, for example, hydrogenation or oxidation reactions. ^^^

[0066] It can also involve inorganic chemistry reactions such as the synthesis of precipitated silica, titanium oxide, calcium carbonate, or inorganic phosphates. ^^^

[0067] The reactor of the invention can also be used for the synthesis of polymers in emulsion or in dispersion and generally makes it possible to achieve a monodisperse population of polymer particles.

[0068] Another very interesting use of the reactor of the invention is its use ^^ to carry out oxidation reactions in supercritical water, for example for the destruction of organic molecules, in particular very stable toxic organic molecules such as polyfluorinated compounds (so-called "eternal pollutants", which are difficult to destroy otherwise). The reactor of the invention makes it possible, due to its specificity, to manage the very particular conditions of this type of reaction. The ^^^ monobloc structure of the reactor, associated with the possibility of the presence of a temperature control circuit, allows the implementation of the high pressure (>221 bars) and high temperatures (>374°C) required for supercritical water.More importantly, the reactor of the invention allows management of the significant precipitation of solids which occurs during the reaction (supercritical water behaves like an apolar solvent and all the mineral salts, initially dissolved in the water or resulting from the oxidation reaction, precipitate). The reactor of the invention allows adequate management of the precipitated solids obtained in this context, avoiding clogging of the reactor.

[0069] Other non-limiting examples of interesting uses of the reactor of the present invention include its use for carrying out continuous crystallization reactions, by forming a suspension of micron solid particles of well-controlled size without risk of clogging of the reactor, the micron powder obtained being able to be recovered by filtration.

[0070] Due to its great modularity and its advantages, the reactor of the invention can be used in many fields including, but not limited to, health, agronomy, paints, reinforcing fillers, electronics, catalysis or cosmetics. Brief description of the drawings

[0071] The accompanying drawings illustrate the invention: ^^^

[0072] Figure 1 [Fig. 1] is a schematic representation of an illustrative embodiment of a single-piece part as present in a reactor according to the invention. ^^^

[0073] Figure 2 [Fig.2] is a partial schematic representation of the same part which describes in detail a possible circuit of reaction medium within twelve channels, which corresponds to the embodiment used in the illustrative example given below. ^^

[0074] Figure 1 [Fig. 1] represents a single-piece part comprising a body 10, generally formed of a single metal or metal alloy and comprising a first series of channels 100, formed of mutually parallel cylinders of cylindrical section (twelve in the Figure), intended to convey a reaction medium, and a second series of channels 200 (present in number of four in the figure ^^^ so as not to overload the diagram, but the part generally comprises more channels), perpendicular to the channels 100 of the first series, and of parallelepiped section, intended to convey a heat transfer fluid. The part further comprises a stud 300, which allows the securing of an ultrasonic source to the body 10 by screwing. ^^^

[0075] Figure 2 [Fig. 2] illustrates a possible example of a circuit made from the channels of the single-piece part. With reference to this diagram, a possible connection of the inputs and outputs of the channels 100 present in the part 10 will now be described, which can be used for the reaction of two reactants, by bringing together a first flow comprising the first reactant (for the example, ^^^ the circuit will be presented considering an aqueous solution of barium chloride) and a second flow comprising the second reactant (aqueous solution of sodium sulfate for the example). According to this illustrative mode, the barium sulfate solution is injected through the inlet 110 of a first channel where it is conveyed to the outlet 111 of said channel.This outlet 111 is in fluid contact with the inlet ^^^ 112 of a second channel (by means of a tube not shown, which is typically part of a first cap covering the rear part of the body 10 carrying in particular the outlets 111 and 112 and pressed against it). The barium sulfate solution is then conveyed to the outlet 113 of the channel. At the same time, the sodium sulfate solution is injected through the inlet 120 of a third channel, ^^^ from which it leaves through the outlet 121, placed in fluid connection (generally by means of a tube typically forming part of the aforementioned cap) with the inlet 122 of a fourth channel to be conveyed to the outlet 123. The two outlets 112 and 123 are placed in fluid connection with the inlet 130 of a fifth tube. ^^^ (generally by means of a tube provided with two inlets and one outlet typically forming part of a second cap placed opposite the aforementioned first cap and pressed against the front face of the body 10, bearing in particular the outlets 110, 113, 120 and 123). A reaction between the barium chloride and the sodium sulfate ^^ then takes place, which leads to the formation of a solid precipitate of barium sulfate.The reaction medium flow then contains a solid and is then conveyed through the rest of the channels as follows: - in a fifth channel, from its inlet 130 to the outlet 131; then - in a sixth channel, from its inlet 132, in fluid connection with the outlet 131 ^^^ of the fifth channel, to its outlet 133; then - in a seventh channel, from its inlet 134, in fluid connection with the outlet 133 of the sixth channel, to its outlet 135; then - in an eighth channel, from its inlet 136, in fluid connection with the outlet 135 of the seventh, to its outlet 137; then ^^^ - in a ninth channel, from its inlet 138, in fluid connection with the outlet 137 of the eighth channel, to its outlet 139; then - in a tenth channel, from its inlet 140, in fluid connection with the outlet 139 of the ninth channel, to its outlet 141; then - in an eleventh channel, from its inlet 142, in fluid connection with the outlet ^^^ 141 of the tenth channel, to its outlet 143.The final reaction medium leaves part 10 through this last outlet 143.

[0076] Example :

[0077] In this example, a reactor was used comprising a parallelepiped monobloc part of 300 mm x 70 mm x 50 mm corresponding to the mode illustrated in ^^^ the Figures and which is made up of a block of metal (316L stainless steel), crossed by 12 cylindrical channels for the reaction mixture (30 cm long, 6 mm in diameter for each of these channels) and by 250 perpendicular channels of rectangular section of 2 x 3 mm for thermal regulation (instead of the four shown in Figure 1). This reactor also includes caps ^^^ ensuring the fluid connections of the reactive reaction medium circuits and thermal regulation and flanges surrounding the assembly ensuring the tightness of the connections. ^^^

[0078] A piezoelectric device generating ultrasonic waves at a frequency of 27.6 kHz and a power of 100 W was screwed onto this single-piece part via the dowel 300 shown in the figure.

[0079] In this example, the sodium sulfate and barium chloride system was used, which leads to rapid and significant precipitation of the insoluble barium sulfate salt.

[0080] The aqueous solutions of barium chloride and sodium sulfate used have a concentration of 0.5 mol / liter and are introduced according to the circuit indicated above at a flow rate of 10 ml / minute for each of the two injected solutions. The barium sulfate dispersion formed is recovered at the outlet of the single-piece part (outlet 143 in Figure 2). The reactor was thermostatically controlled at 18°C ​​by circulating water in the heat transfer circuit.

[0081] A first control experiment was carried out by carrying out the continuous injection of the two solutions for a period of 4 hours under the above conditions, ^^^ in the absence of ultrasonic waves.

[0082] Opening the reactor at the end of the experiment showed a strong fouling of the reactor, at the mixing point of the two reagents (inlet 130). In addition, the first channel receiving the mixture (between inlet 130 and outlet 131) is 95% blocked by a barium sulfate precipitate attached to the walls of the reactor channel ^^^. Rinsing this device with water does not change the appearance of the precipitate, confirming a strong adhesion to the reactor walls.

[0083] The second experiment carried out consisted of reassembling the fouled reactor as it was at the end of the control experiment and continuing the injections, with identical flow rates of the two reagents but this time applying ultrasound at a power of 100 W, frequency of 27.6 KHz, in pulsed mode comprising successive cycles of 1 second under ultrasound then 2 seconds without ultrasound, over a total duration of 6 minutes.

[0084] Opening the reactor at the end of this experiment showed a total absence of barium sulfate precipitate attached to the surface of the channels and at the ^^^ mixing point, which illustrates the embodiment of the invention where the ultrasonic wave is used for "curative" purposes. ^^^

[0085] A third experiment is carried out on a clean reactor, under conditions identical to the first experiment, but by subjecting the reactor to ultrasonic waves at a power of 100 W, frequency 27.6 KHz, in pulsed mode comprising successive cycles of one second under ultrasound then 5 ^^ seconds without ultrasound.

[0086] After 4 hours of experiment, the opening of the reactor shows the total absence of barium sulfate precipitate attached to the surface of the channels or at the mixing point, which illustrates the embodiment of the invention where the ultrasonic wave is used for preventive purposes.

Claims

^^^ Claims

1. Continuous chemistry reactor comprising: - a single-piece part (10) provided with several through channels (100, 200), each of said channels allowing the flow of a fluid through said ^^ single-piece part; and - an ultrasonic source for subjecting the single-piece metal part to an ultrasonic wave, where the through channels are preferably placed in fluid connection with each other to form at least two separate circuits (100; 200), each allowing separate circulation of fluid.

2. Continuous chemistry reactor according to claim 1, wherein the single-piece part is a part formed from a single material having a homogeneous composition over the entire single-piece part, preferably a single metal or a single metal alloy.

3. Continuous chemistry reactor according to claim 1 or 2, wherein the single-piece part comprises between 4 and 15,000, in particular between 10 and 10,000 through channels.

4. Continuous chemistry reactor according to one of claims 1 to 3, where the channels have a cross section of less than 20 mm, preferably less than or equal to 10 mm and a length of between 10 and 1000 mm, preferably between 50 and 600 mm, in particular between 100 and 500 mm.

5. Continuous chemistry reactor according to one of claims 1 to 4, where the volume occupied by the through channels (100, 200) within the single-piece part (10) represents less than 50%, preferably less than 40%, of the total volume of said single-piece part.

6. Continuous chemistry reactor according to one of claims 1 to 5, wherein the through channels are fluidly connected to each other to form at least two separate circuits (100; 200), each allowing separate circulation of fluid, with at least one first circuit (100) allowing circulation of a reaction medium; and at least one second circuit (200) allowing circulation of a fluid ensuring thermal regulation. ^^^

7. Continuous chemistry reactor according to one of claims 1 to 6, wherein the ultrasonic source is a device, preferably a piezoelectric generator, delivering an ultrasonic wave whose frequency is between 16 and 100 kHz, preferably between 18 kHz and 50 ^^ kHz.

8. Continuous chemistry reactor according to one of claims 1 to 7, wherein the ultrasonic source used according to the invention is mechanically connected, and preferably mechanically secured, to the single-piece metal part, for example by screwing.

9. Method for limiting the formation of solid deposits within the through channels of a continuous chemistry reactor according to one of claims 1 to 8, comprising: - at least one step (e) of physical and / or chemical reaction carried out within at least a portion of said through channels (100), wherein said reaction is carried out in the presence of a solid introduced upstream of said through channels (100); and / or said reaction leads, within the through channels (100), to the formation of a solid, and - at least one step (e1) of applying an ultrasonic wave to the single-piece part (10) from the ultrasonic source during said step (e).

10. Method for removing solid deposit formed within the through channels of a continuous chemistry reactor according to one of claims 1 to 8, comprising: - at least one step (e) of physical and / or chemical reaction carried out within at least a portion of said through channels (100), wherein said reaction is carried out in the presence of a solid introduced upstream of said through channels (100); and / or said reaction leads, within the through channels (100), to the formation of a solid, and - at least one step (e2) of applying an ultrasonic wave to the single-piece part (10) from the ultrasonic source after said step (e), whether or not continuing the physical and / or chemical reaction of step (e) during step (e2).

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