Reactor in particular for synthesis of methane and / or methanol, usage of the reactor and method for synthesis of methane and / or methanol

Abstract

The present disclosure relates to a reactor for synthesis of methane and / or methanol in an exothermic reaction. The reactor (1) extends along a longitudinal axis (1) and comprises a structured fixed-bed catalyst (2) extending along the longitudinal axis (l) from an inlet end (21) to an outlet end (25) and comprising a plurality of adjacently arranged channels (31, 32, 33) extending from the inlet end (21) to the outlet end (25). The reactor (1) further comprises a thermal bridge element (3) arranged at least partially within the structured fixed-bed catalyst (2). The thermal bridge element (4) is thermally conductively connected to the structured fixed-bed catalyst (2) and extends along the longitudinal axis (L) from an inlet section (22) of the structured fixed-bed catalyst (2) to a downstream section (23, 24) of the structured fixed-bed catalyst (2) for transferring at least some reaction heat away from the inlet section (22).

Description

[0001] REACTOR IN PARTICULAR FOR SYNTHESIS OF METHANE AND I OR METHANOL, USAGE OF THE REACTOR AND METHOD FOR SYNTHESIS OF METHANE AND I OR METHANOL

[0002] FIELD OF THE DISCLOSRE

[0003] The present disclosure relates to a reactor used in an exothermic reaction, in particular for a synthesis of methane and I or methanol in an exothermic reaction, use of the reactor for synthesis of methane and / or methanol in an exothermic reaction and a method of synthesizing methane and / or methanol in an exothermic reaction.

[0004] BACKGROUND OF THE DISCLOSURE

[0005] The synthesis of methane (methanation) from CO2 (as well as CO) is a strongly exothermic reaction that requires efficient heat removal from the reaction zone, particularly when carried out catalytically with short reaction times. Conventionally, random fixed-bed reactors are used for the synthesis of methane. The random fixed-bed reactors comprises a catalyst pellet bed, in which the synthesis of methane from CO2 and / or CO is performed. The pellet bed of the random fixed- bed reactor defines the reactor zone.

[0006] An alternative to the random fixed-bed reactors are structured fixed-bed reactors with a plurality of channels, which comprise a catalyst coating. These reactors comprise a solid body structure, which define the channels. The reactants stream through the channels and react in the channels with the catalyst coating. The reaction zone is therefore within the channels. For example, the document DE 10 2016 125 641 A1 discloses a process for production of a natural gas substitute from hydrogen-containing gas mixtures using a reactor with channels.

[0007] Regardless of the reactor type employed, the strongly exothermic nature of methane synthesis requires careful control of the heat removal from the reaction zone for controlling the temperature inside the reactor zone. Heat removal of the reaction zone is particularly critical and challenging for structured fixed-bed catalysts. Controlling of the temperature inside the reactor zone is important for ensuring a high quality and high purity product and for ensuring high yields of target product. In particular, the chemical equilibrium of the different chemical reactions taking place is temperature dependent. Typically, it is desirable to maintain the temperature within a narrow target temperature range, in which the balance between high product yield, high product purity and a fast reaction is advantageous. For example, a minimum temperature is typically necessary in order to achieve a high yield of product, but excess temperatures are to be avoided. A further reason why temperature control is important is in order to avoid any damages to the reactor, in particular to the catalyst, due to surpassing of temperature thresholds within the reactor. The same applies to the synthesis of methanol.

[0008] A particular challenge arising from known reactors, such as known structured fixed-bed reactors, are local hotspots in the reaction zone in which the temperature during operation exceeds that of the other parts of the reaction zone. Hotspots may jeopardize product yield and purity and may also lead to physical damage to the reactor, which may in the long term mean that the plant can no longer be operated economically. One approach how hotspots may be prevented is by tuning the process parameters, e.g. reactant flow rates, in order to minimize local hotspots. However, the effect of these approaches is limited and typically insufficient to significantly reduce local hotspots. Furthermore, the known approaches often lead to decreased product yield over time, e.g. when decreasing the reactant flow rate. Additionally, when relying on tuning the process parameters to optimize the process, the tuned parameters are often only optimal for certain load capacities at which the reactor is operated and may not be optimal for different load capacities. Thus, it is a particular challenge to effectively minimize local hotspots independently of the load capacity at which the reactor is operated.

[0009] Further approaches require significant structural modifications of the catalyst employed, which is undesirable as it often necessitates renewed catalyst optimization and does not allow using known and well-established catalysts. Thus, these approaches are also insufficient.

[0010] As a result, there is a need to advance the state of the art with respect to reactors for synthesis of methane and I or methanol in an exothermic reaction.

[0011] SUMMARY OF THE DISCLOSURE

[0012] It is an object of the present disclosure to provide a reactor for exothermic reactions, in particular for a synthesis of methane and I or methanol in an exothermic reaction, a use of said reactor and a method of synthesizing methane and / or methanol in an exothermic reaction. In particular, it is an object of the present disclosure to provide a reactor for synthesis of methane and / or methanol in an exothermic reaction, a use and a method of synthesizing methane and / or methanol which address at least some of the disadvantages of the prior art. Advantageously, it is an object to provide a reactor allowing a high and uniform temperature profile to be achieved. Advantageously, it is an object to provide a reactor minimizing hotspots during operation. Advantageously, hotspots would have a low maximum temperature peak. Furthermore, advantageously, the overall hotspot volume would be minimized.

[0013] According to the present disclosure, these objects are addressed by the features of the independent claims. In addition, advantageous embodiments follow from the dependent claims, figures and the description.

[0014] According to the present disclosure, a reactor is provided, in particular a reactor for synthesis of methane and I or methanol. The reactor extends along a longitudinal axis. The reactor comprises a structured fixed-bed catalyst and a thermal bridge element. The structured fixed-bed catalyst extends along the longitudinal axis from an inlet end to an outlet end and comprises a plurality of adjacently arranged channels extending from the inlet end to the outlet end. The thermal bridge element is arranged at least partially within the structured fixed-bed catalyst. The thermal bridge element is thermally conductively connected to the structured fixed-bed catalyst and extends along the longitudinal axis from an inlet section of the structured fixed-bed catalyst to a downstream section of the structured fixed-bed catalyst, such that during operation at least some reaction heat generated in the inlet section is transferred away from the inlet section. By providing the thermal bridge element that is thermally conductively connected to the structured fixed-bed catalyst, heat that is generated during the reaction may be transferred away from the inlet section. Thus, thermal hotspots are minimized in the inlet section. For example, the heat may be transferred from the inlet section to a downstream section such as an outlet section of the reactor. Depending on the application, the thermal bridge element may in some variants primarily serve to transfer heat away from the inlet section in order to minimize or even fully prevent hotspots in the inlet section. In some variants, the thermal bridge element may additionally serve to optimize temperature profile in the reactor. For example, by transferring heat from the inlet section to a downstream section of the reactor, the thermal bridge element may contribute to a uniformly distributed mean temperature in the reactor. If, for example, the temperature would normally be undesirably high in the inlet section of the reactor and undesirably low in the outlet section of the reactor, the thermal bridge element may, by transferring heat from the inlet section to the outlet section, lead to an optimal temperature in the inlet section as well as the outlet section. The structured fixed-bed catalyst may be virtually separated in an inlet section, comprising the inlet end, a downstream arranged middle section and a further downstream arranged outlet section, comprising the outlet end. Depending on the application, the structured fixed-bed catalyst may be a solid state catalyst.

[0015] The thermal bridge element may further be arranged in areas of expected thermal hotspots within the reactor. Arranging the thermal bridge elements in these areas prevents the heat release during operation at the expected hotspots (e.g. in the radial center of the reactor), which helps to have a uniformly distributed temperature profile during operation. Further, the heat released or generated around the expected hotspot is advantageously removable from this area by the thermal bridge element.

[0016] In some variants, the thermal bridge element extends along the longitudinal axis from the inlet section of the structured fixed-bed catalyst to the outlet section of the structured fixed-bed catalyst, such that during operation at least some reaction heat generated in the inlet section is transferred from the inlet section to the outlet section. One advantage of these variants is that they may for example be used to achieve an advantageous temperature profile throughout the reactor. For example, hotspots may be minimized or even fully prevented in the inlet section, while an advantageous temperature range would also be realized in the outlet section of the reactor. The skilled person understands that in these variants, the thermal bridge element is thermally conductively connected to the structured fixed-bed catalyst in the inlet section and in the outlet section. More generally, in some variants of the reactor disclosed herein, the thermal bridge element is thermally conductively connected to the structured fixed-bed catalyst in the downstream section. The downstream section may for example be the outlet section and / or the middle section of the structured fixed-bed catalyst.

[0017] The thermal bridge element is configured for transferring heat away from the inlet section. Depending on the application, different variants may be used. For example, the thermal bridge element may be separately and / or distinctly formed from the structured fixed-bed catalyst (a plurality of parts arranged inside one another forming the structured fixed-bed catalyst and the thermal bridge element), or the thermal bridge element and the structured fixed-bed catalyst are integrally formed (one single part forming the structured fixed-bed catalyst and the thermal bridge element in combination). Typically, the thermal bridge element contacts the structured fixed-bed catalyst, wherein preferably the thermal bridge element is in direct contact with the structured fixed-bed catalyst. The contacting is typically maintained throughout the inlet section and throughout the downstream section. It may also be conceivable that the thermal bridge element contacts the structured fixed- bed catalyst indirectly, e.g. via distance spacers or distance rods.

[0018] The released heat during the operation of the reactor may be transferred via heat conduction, heat convection and I or heat radiation to the thermal bridge element. The heat is transferred via heat conduction axially along the thermal bridge element, and may be released back in the structured fixed-bed catalyst via heat conduction, heat convection and / or heat radiation.

[0019] In some variants, the thermal bridge element comprises a rod, in particular a metal rod, extending parallel with respect to the longitudinal axis. For example, the thermal bridge element may consists of a single rod extending parallel with respect to the longitudinal axis.

[0020] In some variants, the thermal bridge element may comprise or consist of a plurality of rods, in particular metal rods, wherein at least one or even all of the rods may extend parallel with respect to the longitudinal direction. The rod or rods may have different shapes and / or geometries. For example, in some variants, the rod has a circular cylindrical shape or a polygonal cylindrical shape. In some variants, the rod has a polygonal prismatic shape. The rod may be cylindrical, but the rod may also at least partially taper towards one axial end. For example, in some variants, the diameter or a radial extension of the rod decreases or increases along the longitudinal axis, e.g. towards the inlet end and / or towards the outlet end. By varying the diameter or the radial extension along the longitudinal axis, the heat transfer may be controlled and the temperature profile in the reactor may thereby be optimized. For example, a large circumference may be used to achieve effective transfer of heat away from a given section, such as the inlet section, while a smaller circumference may be desirable to distribute the head transfer over a larger volume of the reactor. Thus, in some variants, the circumference of the rod is larger in the inlet section than in the downstream section.

[0021] Depending on the application, the thermal bridge element may have different physical and / or geometrical properties. For example, in the some variants, a maximal radial extension of the thermal bridge element is at least 50% larger, preferably at least 200% larger, more preferably at least 400% larger, even more preferably at least 600% larger than a wall thickness of a catalyst wall separating at least two channels of the structured fixed-bed catalyst. The radial direction is typically orthogonal to the longitudinal axis. The maximal radial extension may for example be an outer diameter of the thermal bridge element. By having a maximal radial extension at least 50% larger than the wall thickness of the catalyst wall, the overall heat transferred away through the thermal bridge element may be significantly larger than the overall heat transferred away through the catalyst channel walls. In some variants in which the reactor comprises two or more thermal bridge element, for example, each thermal bridge element may have a maximal radial extension of the thermal bridge element that is at least 50% larger, preferably 200% larger, more preferably at least 400% larger, even more preferably at least 600% larger than a wall thickness of a catalyst wall separating at least two channels of the structured fixed-bed catalyst. If the maximal radial extension of the thermal bridge element differs along the longitudinal axis, then in some variants, the maximal radial extension may be provided as the mean maximal radial extension.

[0022] In some variants, the thermal bridge element has a maximal radial extension of at least 2%, preferably at least 5%, more preferably from 5% to 50%, even more preferably from 10% to 40%, of a maximal radial extension of the structured fixed- bed catalyst. If the maximal radial extension of the thermal bridge element varies along the longitudinal direction, the maximal radial extension of the thermal bridge element may for example be provided as a mean maximal radial extension of the thermal bridge element. The maximal radial extension of the thermal bridge element respectively of the structured fixed-bed catalyst may for example be an outer diameter of the thermal bridge element respectively of the structured fixed- bed catalyst. If the reactor comprises two or more thermal bridge element, then a sum of all maximal radial extensions of all thermal bridge elements may in some variants have a maximal radial extension of at least 2%, preferably at least 5%, more preferably from 5% to 50%, even more preferably from 10% to 40%, of a maximal radial extension of the structured fixed-bed catalyst.

[0023] Depending on the application, the properties and / or geometry of the thermal bridge element may vary along an axial extension of the thermal bridge element. The axial extension of the thermal bridge element is the extension of the thermal bridge element along the longitudinal direction of the reaction, in other words along the main flow direction during its operation. In some variants, a geometrical extension of the thermal bridge element varies along its axial extension. For example, one or more of the following geometrical extensions of the thermal bridge element may vary along the axial extension of the thermal bridge element: a maximal radial extension of the thermal bridge element, an outer contour of the thermal bridge element, a cross sectional shape of the thermal bridge element and / or a cross sectional surface area of the thermal bridge element. In some variants, for example, an outer diameter of the thermal bridge element may vary along the axial extension of the thermal bridge element. By varying the geometrical extension along the axial extension, the amount of heat transferred and the rate of heat transfer may be fine-tuned. In some variants, an effective thermal conductivity of the thermal bridge element varies along its axial extension, e.g. by using different material composition along the axial extension.

[0024] Depending on the application, the thermal bridge element may in some variants comprise at least one lateral protrusion extending radially from a longitudinal main body of the thermal bridge element. For example, the lateral protrusion may be a lateral arm. In some variants, the reactor comprises two or more lateral protrusions, which are preferably arranged peripherally around the longitudinal main body, in particular in an equidistant fashion with respect to each other. For example, the lateral protrusions may be arranged peripherally around the longitudinal main body in a point-symmetrical fashion with respect to a central longitudinal axis and in a cross section orthogonal to the longitudinal direction. One advantage of providing at least one lateral protrusion is that they may contribute to a homogenous temperature profile in particular also in radial direction. For example, a temperature distribution in radial direction may be improved by providing lateral protrusions. Thus, the efficiency of heat transfer away from critical hotspots may be enhanced.

[0025] Depending on the application, the thermal bridge element may be made of different materials and may have different properties. For example, in some variants, the thermal bridge element has a thermal conductivity equal to or greater than the thermal conductivity of the structured fixed-bed catalyst. The thermal conductivity is a material property and, as such, the thermal conductivity of the thermal bridge element typically depends primarily on the material of which the thermal bridge element is made. The thermal bridge element and the structured fixed-bed catalyst may in some variants be made of the same material. Nevertheless, in these embodiments, a total amount of heat transferred through the thermal bridge element may, depending on the application, still be larger than a total amount of heat transferred through the structured fixed-bed catalyst, because the thermal bridge element may for example be a massive body, whereas the structured fixed-bed catalyst typically comprises a plurality of channels. In some variants, the structured fixed-bed catalyst is made of a different material than the thermal bridge element. Depending on the application, the thermal bridge element may be made of or comprises a metal. For example, the thermal bridge element may be made of steel, copper or aluminum. In some variants, the thermal bridge element has a thermal conductivity of at least 5 W / mK, preferably of at least 10 W / mK, more preferably of at least 15 W / mK. In some variants, the thermal bridge element has a thermal conductivity of at least 20 W / mK, for example from 20 W / mK to 300 W / mK. In some variants, the thermal bridge element has a thermal conductivity from 100 W / mK to 300 W / mK. In further variants, the thermal bridge element has a thermal conductivity from 20 W / mK to 100 W / mK. Depending on the application, the thermal bridge element may be made of the same material as the structured fixed-bed catalyst or it may be made of a different material than the structured fixed-bed catalyst. For example, in some variants, the structured fixed-bed catalyst is made of steel and the thermal bridge element is made of a different steel. Depending on the application, the material of which the structured fixed-bed catalyst is made may have a surface that is catalytically inactive.

[0026] In some variants, the thermal bridge element and the structured fixed-bed catalyst may be chosen such that their respective thermal expansion coefficients are similar. For example, in some variants, a thermal expansion coefficient of the thermal bridge element is within 25%, preferably within 10%, more preferably within 5%, of a thermal expansion coefficient of the structured fixed-bed catalyst.

[0027] Depending on the application, the thermal bridge element may be a solid body or at least 70%, preferably at least 85% of a total volume of the thermal bridge element may be a solid body. In some variants, the thermal bridge element comprises at least one opening, cavity or bore. The opening, cavity or bore may for example be arranged concentric or eccentric within the thermal bridge element. The opening, cavity or bore may in some variants be a blind-hole. Depending on the application, the opening or bore may have different depths. For example, a depth of the bore may be chosen such that the bore ends before an expected hotspot area. This may for example be desirable to control axial heat transfer. For example, in some variants, the bore extends from a first axial end and ends before the expected hotspot area. In some variants, the bore has a depth of up to 200 mm, preferably of up to 100 mm. Further, in some variants, the bore has a depth in longitudinal direction of at least 25 mm, preferably at least 50 mm, more preferably of 75 mm. In some variants, the opening or bore has a depth in longitudinal direction of at least 25%, preferably 50%, more preferably 75% of a total axial length of the thermal bridge element in longitudinal direction. In some variants, a first axial end and I or a second axial end of the thermal bridge element comprises the bore. The first axial end is arranged opposite a second axial end in longitudinal direction. The first axial end is arranged closer to the inlet end and the second end is arranged closer to the outlet end.

[0028] Depending on the application, the reactor may comprise one thermal bridge element or the reactor may comprise two or more, for example from two to ten, thermal bridge elements. In some variants, the two or more thermal bridge elements are arranged uniformly with respect to each other and with respect to the structured fixed-bed catalyst within the reactor. For example, the two or more thermal bridge elements may be arranged symmetrically with respect to each other and with respect to the structured fixed-bed catalyst. The symmetrical arrangement may in some variants relate to point-symmetry in a cross section orthogonal to the longitudinal axis. For example, in a cross section orthogonal to the longitudinal axis, the thermal bridge elements may in some variants be arranged in a point-symmetrical fashion with respect to a central longitudinal axis of the reactor. In some variants, at least some of the thermal bridge elements may be arranged eccentric within the structured fixed-bed catalyst and those thermal bridge elements being arranged eccentric within the structured fixed-bed catalyst may be equidistant to each other in a cross section orthogonal to the longitudinal axis. Alternatively or in combination, the reactor may include a thermal bridge element being arranged concentrically within the structured fixed-bed catalyst. One advantage of the embodiments described in this paragraph is that they contribute to a balanced temperature profile in the reactor, in particular a balanced temperature profile both in the longitudinal direction and in radial direction within the reactor during its operation. By providing two or more thermal bridge elements, the head transfer may be further optimized.

[0029] Depending on the application, the thermal bridge element have different arrangements. For example, the thermal bridge element may be arranged at least partially or entirely within the structured fixed-bed catalyst. The thermal bridge element may in some variants be arranged centrally within the structured fixed-bed catalyst. In some variants, the thermal bridge element is arranged coaxially with the structured fixed-bed catalyst. Depending on the application, the thermal bridge elements may in some variants be arranged concentrically or eccentric with respect to the structured fixed-bed catalyst. It is also possible that the reactor may comprise two or more thermal bridge elements and that at least one of the two or more thermal bridge elements is arranged concentrically with respect to the structured fixed-bed catalyst and that at least one of the two or more thermal bridge elements is arranged eccentric with respect to the structured fixed-bed catalyst. The terms “concentrical” and “eccentrical” as used herein typically refer to the longitudinal axis of the reactor, preferably to a central longitudinal axis of the reactor.

[0030] Depending on the application, the thermal bridge element may have different arrangements with respect to the structured fixed-bed catalyst. For example, in some variants, at least the part of the thermal bridge element that is arranged within the structured fixed-bed catalyst is at least partially surrounded circumferentially by the structured fixed-bed catalyst, preferably fully surrounded circumferentially by the structured fixed-bed catalyst. For example, in a cross section orthogonal to the longitudinal direction, the thermal bridge element may be encompassed by the structured fixed-bed catalyst. Depending on the application, the thermal bridge element may contact at least one channel. For example, in some variants, at least five, more preferably at least 20 channels contact the thermal bridge element circumferentially. The channels may contact the thermal bridge element along a part of a length in longitudinal direction of the thermal bridge element, or along the entire length in longitudinal direction of the thermal bridge element. Depending on the application, at least some of the channels may extend in parallel to the thermal bridge element in longitudinal direction. It is also possible that at least some of the channels extend helically with respect to an outer contour of the thermal bridge element.

[0031] In a further variation, the thermal bridge element is at least partially coated or covered by a structured fixed-bed catalyst material, thereby forming partially the structured fixed-bed catalyst.

[0032] In some variants, the thermal bridge element protrudes from the structured fixed- bed catalyst at the inlet end of the structured fixed-bed catalyst. For example, up to 30%, preferably up to 15%, more preferably up to 8% of the length in longitudinal direction of the thermal bridge element may protrude from the structured fixed-bed catalyst at the inlet end of the structured fixed-bed catalyst. Thus, for example, at least 70%, preferably at least 85%, more preferably at least 92% of the length in longitudinal direction of the thermal bridge element may be arranged within the structured fixed-bed catalyst. One advantage of these embodiments is that they further reduce the risk of hotspots and / or reduce the temperature magnitude or temperature peak of hotspots. Without wishing to be bound to a theory, it is believed that the heat may at least partially be transferred away from the inlet section in two directions. Preferably, an outer contour of a protruding tip of the thermal bridge element protruding from the structured fixed-bed catalyst at the inlet end may be shaped in a streamlined fashion. For example, the outer contour of the protruding tip may be configured to minimize turbulence. As an example, a radial extension of the protruding tip may taper towards a tip point. The protruding portion may further function as a distance element with respect to a downstream- or upstream arranged reactor.

[0033] The reactor is in particular configured for the synthesis of methane and I or methanol in an exothermic reaction, preferably for the synthesis of methane. Typically, the methanation is carried out at a preferred temperature in a range from 150 °C to 500 °C, preferably in the range from 200°C to 450°C. Maximum temperatures within the reactor may reach 350 °C to 450 °C.

[0034] In a typical embodiment, the structured fixed-bed catalyst is configured for catalytic conversion of reactants to methane and / or methanol. In an embodiment, the structured fixed-bed catalyst comprises a body structure. The body structure itself may for example be the catalyst. In other words, the body structure itself may be catalytically active. In another embodiment, the body structure is coated with a catalytically active layer. In this embodiment, the body structure provides the de- sired surface area for the reaction, but the coating provides the catalytic functionality. The catalytically active material, for example the coating or the body structure itself, comprises for instance a washcoat, which comprises for instance porous aluminum oxide for a surface increase, and the catalytically active substances. The catalytically active substances are for example based on nickel, platinum, rhodium and I or palladium or a combination thereof. In case of coating, the coated body structure, the carrier, may be formed out of or comprises aluminum oxide (AI2O3). The body structure may for example made of a temperature resistant ceramics like cordierite or preferably metals.

[0035] In an embodiment, the reactor comprises a plurality of structured fixed-bed catalysts, which are arranged in series with respect to each other. The reactor preferably has an elongated cylindrical shape, along which the reactants flow during operation.

[0036] The thermal bridge element may for example be at least partially arranged within two or more structured fixed-bed catalysts. For example, the thermal bridge element may extend from a first structured fixed-bed catalyst to a second structured fixed-bed catalyst arranged upstream or downstream of the first structured fixed- bed catalyst.

[0037] The reactor comprises a structured fixed-bed catalyst. The structured fixed-bed catalyst comprises an inlet end and an outlet end. Typically, the inlet end is an upstream end and the outlet end is a downstream end. The outlet end is typically arranged opposite in longitudinal direction from the inlet end. During operation, the reactant or reactants flow through the inlet end into the reactor, pass in longitudinal direction through the channels and exit the reactor through the outlet end. The structured fixed-bed catalyst further typically comprises an inlet section, a middle section and an outlet section. The inlet section is typically arranged upstream of the middle section, which is typically arranged upstream of the outlet section. Depending on the application, the different sections may have different lengths. For example, in some variants, the inlet section may extend from the inlet end for up to 40%, preferably up to 30%, more preferably up to 25% of a length of the structured fixed-bed catalyst in longitudinal direction. Alternatively or in combination, the outlet section may extend from the outlet end for up to 40%, preferably up to 30%, more preferably up to 25% of a length of the structured fixed-bed catalyst in longitudinal direction.

[0038] In a variant, the structured fixed-bed catalyst comprises a main body forming the plurality of adjacently arranged channels. The channels are typically configured to enable reactants to flow through the main body during operation of the reactor. Depending on the application, the channels may be through-going. Typically, each of the channels extends continuously from the inlet section to the outlet section. Depending on the application, the number of channels may vary. For example, in some variants, the structured fixed-bed catalyst may include a plurality of at least 100 channels, each extending from the inlet end to the outlet end. In some variants, the number of channels is for example in a range from 100 to 1000, preferably in a range from 250 to 450. The channels advantageously increase the available surface within the catalyst for an advantageous synthesis. The channels have for example a circular, an angular, a rectangular, a squared and / or a honeycomb shape. Depending on the application, the channels may have different geometries. In some variants, each channel of the structured fixed- bed catalyst has a maximal radial extension from 0.2 mm to 5 mm, preferably from 0.3 mm to 3 mm. The maximal radial extension of the channel may for example be a channel diameter.

[0039] Typically, two adjacent channels are separated from each other by at least a portion of a catalyst wall. The catalyst wall has a wall thickness. Depending on the application, the wall thickness is typically small compared to a maximal radial extension of the thermal bridge element.

[0040] The reactor may further comprise an outer reactor wall. Typically, the structured fixed-bed catalyst and the thermal bridge element are arranged within the outer reactor wall. In some variants, the thermal bridge element and the structured fixed-bed catalyst are arranged co-axially with the outer reactor wall. The reactor may further comprise a coolant channel surrounding at least partially the structured fixed-bed catalyst and the thermal bridge element and configured to guide coolant along the reactor wall for further cooling of the reactor during its operation. The coolant use comprises for example, water, glycol, oil or a mixture thereof.

[0041] In a further variation, the thermal bridge element, in particular its shape, its radial and axial dimensions, position within the structured fixed-bed catalyst and I or its material composition, is selected based on an expected thermal profile of the reactor during its operation for an optimized synthesis within the reactor. In other words, the thermal bridge element is designed and I or selected based on the application used for the reactor. E.g. in some applications, a small short thermal bridge element may be advantageous, whereas in other applications a large thermal bridge element having lateral protrusions may be advantageous.

[0042] In a second aspect, the present disclosure relates to use of the reactor according to any one of the embodiments disclosed herein for synthesis of methane and / or methanol in an exothermic reaction.

[0043] In a third aspect, the present disclosure relates to a method of synthesizing methane and / or methanol in an exothermic reaction. The method comprises providing the reactor according to any one of the embodiments disclosed herein and reacting hydrogen with carbon dioxide, carbon monoxide or a mixture thereof in the reactor.

[0044] In an embodiment, the synthesis of methane involves methanation of carbon dioxide and / or carbon monoxide. It is typically carried out at temperatures up to 600 °C. Preferably, the reaction is controlled such that the temperature inside the catalyst does not exceed 700 °C, preferably such that it does not exceed 650 °C, preferably such that it does not exceed 600 °C, preferably such that it does not exceed 550 °C, preferably such that it does not exceed 500 °C. As outlined above, in some variants, the reaction is carried out at a preferred temperature in a range from 150 °C to 500 °C, preferably in the range from 200 °C to 450 °C.

[0045] It is to be understood that both the foregoing general description and the following detailed description present embodiments, and are intended to provide an overview or framework for understanding the nature and character of the disclosure. The accompanying drawings are included to provide a further understanding, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments, and together with the description serve to explain the principles and operation of the concepts disclosed.

[0046] BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The present disclosure will be more fully understood from the detailed description given herein below and the accompanying drawings, which should not be considered limiting to the disclosure described in the appended claims. The drawings are showing:

[0048] Fig. 1 a perspective view of a reactor according to a first variation;

[0049] Fig. 2 a top view of the reactor as shown in Figure 1 ;

[0050] Fig. 3 a longitudinal section view of the reactor along the section line A-A as indicated in Figure 2;

[0051] Fig. 4 a schematic section view of a reactor according to a second variation;

[0052] Fig. 5 a first schematic longitudinal section view showing a first variation of a thermal bridge;

[0053] Fig. 6 a second schematic longitudinal section view showing a second variation of the thermal bridge;

[0054] Fig. 7 a third schematic longitudinal section view showing a third variation of the thermal bridge;

[0055] Fig. 8 a fourth schematic longitudinal section view showing a fourth variation of the thermal bridge;

[0056] Fig. 9 a perspective view of a contact body according to a first variation arranged between a reactor wall and a coolant channel; Fig. 10 a perspective view of a contact body according to a second variation arranged between a reactor wall and a coolant channel;

[0057] Fig. 11 a first temperature profile of the reactor;

[0058] Fig. 12 a second temperature profile of the reactor;

[0059] Fig. 13 a third temperature profile of the reactor;

[0060] Fig. 14 a first conversation diagram;

[0061] Fig. 15 a second conversation diagram;

[0062] Fig. 16 - 22 temperature profile diagrams.

[0063] DESCRIPTION OF THE EMBODIMENTS

[0064] Reference will now be made in detail to certain embodiments, examples of which are illustrated in the accompanying drawings, in which some, but not all features are shown. Indeed, embodiments disclosed herein may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Whenever possible, like reference numbers will be used to refer to like components or parts.

[0065] The Figures 1, 2 and 3 show a first exemplary embodiment of a reactor 1 . The reactor 1 comprises a structured fixed-bed catalyst 2, which comprises a catalyst body structure 27 defining a plurality of channels 31 , 32, 33 within the structured fixed-bed catalyst 2, along which the reactants stream during operation of the reactor 1 . The catalyst body structure 27 defines at least partially the reaction zone of the catalyst 2, in which the synthesis of methane takes place during operation of the reactor 1 . In this embodiment, the catalyst body structure 27 comprises a catalyst coating 28, which comprises the catalytically active materials. The catalyst body structure 27 provides the desired large surface and the coating 28 provides the catalytically active materials. The catalyst body structure 27 of the structured fixed-bed catalyst 2 has a circular cylindrical shape (other shapes are also conceivable) and is surrounded on its shell surface by a catalyst body wall 29, which is for example made of sheet metal. The reactor 1 as presented in the figures further comprises a channel shaped reactor wall 1 1 , which is for example a pipe or tube and in which the structured fixed-bed catalyst 2 is positioned. The catalyst 2 and the reactor wall 1 1 are preferably arranged coaxially with respect to each other, as best visible in the Figures 1 and 2. Figure 1 advantageously shows a longitudinal axis L of the reactor 1 along which the different parts of the reactor 1 extend.

[0066] The reactor 1 according to this variation further comprises a contact body 5, which is arranged between the structured fixed-bed catalyst 2, in particular between the catalyst body wall 5, and the reactor wall 1 1 . The contact body 5 is configured to contact both parts for transferring heat from the catalyst 2 to the reactor wall 1 1 during operation of the reactor 1 . The contact body 5 completely surrounds the at least one catalyst 2 as best visible in Figure 2. The contact body 5 is made of a corrugated sheet metal and contacts with first contact portions the catalyst 2 and with second contact portions the reactor wall 1 1 . The contact body 5 further may comprise a contact body coating, which comprises catalytically active materials such that a bypass flow of reactants streaming along a gas gap between the reactor wall 1 1 and the catalyst 2 during operation of the reactor 1 also contact the contact body coating, thus catalyzing the chemical transformation of the reactants to methane. The contact body 5 is preferably fixedly arranged within the reactor 1 by an adhesive joint, for example a soldering seam or a welding seam, which extends axially or in circumferential direction (or in both directions, like a helix) between the contact body 5 and I or the catalyst 2 and the reactor wall 1 1 . The adhesive joint further advantageously increases the heat transfer between the different parts. The adhesive joint further may be configured to position the catalyst 2 by the contact body 5 within the reactor 1 .

[0067] The Figures 1 , 2 and 3 further show a cooling wall 6, which surrounds the reactor wall 1 1 and which thereby provides a cooling channel 61 for a coolant flow during operation of the reactor 1 . The cooling wall 6 is arranged preferably coaxially with respect to the structured fixed-bed catalyst 2, the contact body 5 and the reactor wall 1 1 , which enables that the coolant channels 61 has a constant thickness in circumferential direction which improves the heat transport.

[0068] The contact body 5 as shown in the Figures 1 , 2 and 3 has an oversize with respect to the radial outer surface of the catalyst body wall 29 and the radial inner surface of the reactor wall 1 1 such that at least an elastic deformation is caused when the contact body 5 is inserted into the reactor 1 .

[0069] The Figures 1 , 2 and 3 further indicate schematically catalyst channels 31 , 32, 33, which are defined by the catalyst body structure 27 of the catalyst 2. The catalyst channels 31 , 32, 33, have for example a circular, an angular, a rectangular, a squared or a honeycomb shape. The catalyst 2 comprises for example 250 to 500 channels determined by the catalyst body structure 27, which is for example made of ceramic or metal.

[0070] The Figures"! , 2 and 3 further advantageously show a thermal bridge element 4 arranged within the structured fixed-bed catalyst 2. The thermal bridge element 4 has according to this embodiment a rod like shape or a circular cylindrical shape and is arranged concentrically with respect to the structured fixed-bed catalyst 2 and the reactor 1 . The thermal bridge element 4 is thermally conductively connected to the structured fixed-bed catalyst 2 and extends throughout the structured fixed-bed catalyst 2, in particular from an inlet end 21 to an outlet end 25 of the structured fixed-bed catalyst 2, thereby extending from an inlet section 22 to an outlet section 24 via a middle section 23 of the structured fixed-bed catalyst 2. Both shown catalyst 2 comprise the thermal bridge element 4.

[0071] Figure 3 advantageously shows a plurality of the catalysts 2 arranged in series with respect to each other. The catalysts 2 are arranged axially next to each other. The catalyst 2 arranged downstream and the catalyst 2 arranged upstream comprise both the thermal bridge element 4 and contact the contact body 5 via the catalyst body wall 29.

[0072] Figure 3 further advantageously shows the gas gap between the catalysts 2 and the reactor wall 1 1 in which the contact body 7 is arranged. Figure 3 further shows a streaming direction of the reactants along the structured fixed-bed catalyst 2 and a streaming direction of the coolant within the cooling channel 61 . Figure 3 further shows that the catalysts 2 do not contact each other at its respective axial ends. An intermediate zone is arranged between the two catalysts 2 in axial direction. The intermediate zone has the advantage that the reactants can mix again after outflowing from the downstream catalyst 2 and prior to inflowing into the upstream catalyst 2. In another embodiment, the catalysts 2 contact each other axially. Figure 3 further advantageously show the centrally arranged thermal bridge elements 4 within both catalysts 2.

[0073] Figure 4 shows the reactor 1 with a plurality of structured fixed-bed catalysts 2 within the reactor wall 1 1 , in particular with four catalysts 2 all arranged in series with respect to each other. Figure 4 further shows schematically the contact body 5 contacting all of the catalysts 2 thereby positioning the catalysts 2 coaxially with respect to each other and coaxially with respect to the reactor wall 1 1 , which surrounds the catalysts 2 and the contact body 5. Figure 4 further shows a counter-flow of the coolant with respect to the flow direction of the reactants during operation of the reactor 1 . Figure 4 further advantageously shows the rod like thermal bridge element 4 arranged centrally within the four catalysts 2.

[0074] Figure 5 shows a reactor 1 with two in series arranged structured fixed-bed catalysts 2. Both catalysts 2 comprise the thermal bridge element 4 according to different embodiments. The upstream arranged structured fixed-bed catalyst 2 comprises a thermal bridge element 4, which extends from the inlet end 21 to the outlet end 25 of the catalyst 2. Further, the thermal bridge element 4 comprises an opening 43 extending from an axial end of the thermal bridge element 4 into the thermal bridge element 4. The opening affects the thermal conductivity of the thermal bridge element 4. The downstream arranged structured fixed-bed catalyst 2 also comprises a thermal bridge element 4. According to this embodiment, the thermal bridge element 4 extends from the inlet end 21 to the outlet section 24 but not to the outlet end 25. Further, the thermal bridge element 4 comprises an opening, bore or cavity 43 extending from the axial end of the thermal bridge element 4 arranged at the outlet section 24 into the thermal bridge element 4.

[0075] Figure 6 further shows the reactor 1 with two in series arranged structured fixed- bed catalysts 2 comprising each a thermal bridge element 4 according to a further embodiment. The thermal bridge element 4 according to the embodiment as shown in the upstream arranged catalyst 2 comprises a plurality of rod like thermal bridge elements 4. The main thermal bridge element 4 is arranged centrally, in particular coaxially, with respect to the catalyst 2 and has a larger radial extension compared to the peripheral thermal bridge elements 4, which are smaller, in particular have a smaller radial extension. The structured fixed-bed catalyst 2 according to this embodiment may comprise three, four, five, six or eight peripheral thermal bridge elements 4, which are distributed circumferentially equidistant around the main thermal bridge element 4. The structured fixed-bed catalyst 2 arranged downstream comprises a thermal bridge element 4 according to a different embodiment. The thermal bridge element 4 comprises a main body 41 arranged centrally, in particular coaxially, with respect to the catalyst 2, and further comprises lateral protrusions 42, which extend from the main body 41 radially into the structured fixed-bed catalyst 2. The lateral protrusions 42 advantageously transfer the released heat towards radially peripheral portions of the catalyst 2. The protrusions 42 may have a spike shape or may have a cylindrical shape, surrounding partially or entirely the main body 41 . In a further embodiment, the lateral protrusions 42 may be implemented as fins.

[0076] Figure 7 shows the reactor 1 with two in series arranged structured fixed-bed catalysts 2 comprising each a thermal bridge element 4 according to a further embodiment. The thermal bridge element 4 according to the embodiment as shown in the upstream arranged catalyst 2 comprises a plurality of thermal bridge elements 4, the main thermal bridge element 4 is arranged centrally and the peripheral thermal bridge elements 4 are arranged laterally spaced apart from the main thermal bridge element 4 in the center. The main thermal bridge elements 4 extends from the inlet end 21 to the outlet end 25. The peripheral thermal bridge elements 4 extend from the inlet end 21 towards the outlet section 24 without reaching the outlet end 25. The thermal bridge element 4 according to the embodiment as shown in the upstream arranged catalyst 2 comprises protrusions 42 which extend from the inlet section 22 of the structured fixed-bed catalyst 2 to the outlet section 24 of the structured fixed-bed catalyst 2 at a predefined angle in radial and axial direction.

[0077] Figure 8 shows the reactor 1 with two in series arranged structured fixed-bed catalysts 2 comprising each a thermal bridge element 4 according to a further embodiment. The thermal bridge element 4 according to the embodiment as shown in the upstream arranged catalyst 2 extends from the inlet end 21 to the outlet end 25. Further, the thermal bridge element 4 is tapered, which affects the thermal conductivity. According to this embodiment, the radial extension at the inlet end 21 is larger compared to the radial extension at the outlet end 25. The thermal bridge element 4 of the downstream catalyst is also tapered, but the other way around. The radial extension at the inlet end 21 is smaller compared to the radial extension at the outlet end 25.

[0078] The Figures 5 to 8 further advantageously show the catalyst body structure 27 forming the catalyst channels 31 , 32, 33 surrounding the thermal bridge element 4. Further, the figures show the catalyst body wall 29 forming the outer radial shell of the respective catalyst 2. In addition, the reactor wall 1 1 is shown, which surrounds all of the structured fixed-bed catalysts 2. A combination of the embodiments of the thermal bridge elements 4 as shown in the figures is of course also conceivable.

[0079] Figure 9 shows in a perspective view of the contact body 5 of the reactor 1 of Figures 1 to 3. The contact body 5 extends in axial direction along the longitudinal axis L and is for example made of a corrugated sheet metal such that the desired wave-like cross section of the contact body 5 is realized. The contact body 7 preferably comprises a contact body coating 8, which comprises the catalytically active materials. Figure 10 shows in a perspective view another embodiment of the contact body 7 having a star like cross section.

[0080] Figure 11 shows a first temperature diagram 100 according to a first embodiment of the reactor 1 comprising no thermal bridge element. Figure 1 1 shows the 3D temperature profile within the structured fixed-bed catalyst 2 in radial direction (x- axis) and in axial direction (y-axis) of the structured fixed-bed catalyst 2. The diagram 100 shows the temperature on the z-axis. This nomenclature is also applicable on the diagrams shown in the Figures 12 and 13. It is visible that the temperature peaks at the inlet section 22 at around 451 °C. The middle section 23 and the outlet section 24 of the structured fixed-bed catalyst 2 are relatively cool. The temperature of the coolant flowing around the reactor 1 in the cooling channel 61 is 299,85 °C and the overall conversion rate of CO2 is 98,618 %.

[0081] Figure 12 shows a second temperature diagram 1 10 according to a second embodiment of the reactor 1 comprising the thermal bridge element 4 implemented as a steel rod arranged centrally in the catalyst 2. It is visible that the temperature peaks in the inlet section 22 lateral the thermal bridge element 4. It is further visible that the thermal bridge element 4 transports heat from the inlet section 22 downstream in the middle section 23 and the outlet section 24. The overall temperature profile is smoother. Further, the temperature peak is lower compared to the temperature peak of the reactor 1 without thermal bridge element 4, in particular it is almost 75 Kelvin lower. Figure 12 therefore advantageously shows the effect of the thermal bridge element 4. The coolant temperature is 269,85°C and the conversation rate of CO2 is 93,433%.

[0082] Figure 13 shows a third temperature diagram 120 according to a third embodiment of the reactor 1 comprising the thermal bridge element 4 implemented as a steel rod. This embodiment corresponds mainly with the embodiment as shown in Figure 12, with the difference that the coolant temperature is higher, it is 299,85°C, which results in an even higher conversation rate of CO2 of 94,444%.

[0083] Figures 14 shows a first sensitivity diagram 130 and Figure 15 shows a second sensitivity diagram 140. The first sensitivity diagram 130 shows the reactor 1 without thermal bridge element 4 and the second sensitivity diagram 140 show the reactor 1 with the thermal bridge element 4. Both diagrams 130, 140 show the catalyst temperature as dashed grey lines in dependence of the inlet / coolant temperature in °C, and the CO2 conversation rate as black line (solid) in dependence of the inlet / coolant temperature in °C. It is advantageously visible that the thermal bridge element 4 does not affect the conversation rate significantly at coolant temperatures of above 270°C. But the maximum catalyst temperature can be reduced significantly by the introduction of the thermal bridge element 4.

[0084] The Figures 16 to 22 show different two dimensional temperature profile diagrams 150, 160, 170, 180, 190, 200, 210. Each of these diagrams 150, 160, 170, 180, 190, 200, 210 shows two temperature profiles in [°C] along the axial extension in [cm] of the structured fixed-bed catalyst 2. The dashed line is the radial average temperature and the dash-dotted line is the maximum temperature in the catalyst 2. The solid line is the temperature of the thermal bridge element 4.

[0085] Figure 16 shows the temperature profile diagram 150 of a reactor 1 without a thermal bridge element 4. The maximum temperature reaches almost 450 °C at ca. 1 cm in axial direction. The average temperature reaches almost 400 °C at ca. 1 cm in axial direction. The temperature drops dramatically downstream. The coolant temperature Toi is 270°C, the ration between the maximum temperature to the average temperature Tv is 1 ,1828 and the methane conversation rate YCH4 is 96,8842 %.

[0086] Figure 17 shows the temperature profile diagram 160 of the reactor 1 with a thermal bridge element 4 having a diameter of 0,5cm and being arranged coaxially within the catalyst 2. The thermal bridge element 4 according to this embodiment is made of the same steel as the catalyst body structure 27 of the catalyst 2. It is visible that the maximum temperature reaches only ca. 41 C C at ca. 1 cm in axial direction. The average temperature reaches only ca. 375°C at ca. 1 cm in axial direction. The coolant temperature Toi is 270°C, the ration between the maximum temperature to the average temperature Tv is 1 ,239 and the methane conversation rate YCH4 is 96,4221 % and the outer diameter of the thermal bridge element 4 dwb is 0,5 cm. Figure 17 shows that the same conversation rate is achievable at lower temperatures having the thermal bridge element 4.

[0087] Figure 18 shows the temperature profile diagram 170 of the reactor 1 with a thermal bridge element 4 having a diameter of 1 cm and being arranged coaxially within the catalyst 2. The thermal bridge element 4 according to this embodiment is made of the same steel as the catalyst body structure 27 of the catalyst 2. It is visible that the maximum temperature reaches only ca. 400°C at ca. 1 cm in axial direction. The average temperature reaches only ca. 370°C at ca. 1 cm in axial direction. The coolant temperature Toi is 270°C, the ration between the maximum temperature to the average temperature Tv is 1 ,0962 and the methane conversation rate YCH4 is 95.6281 % and the outer diameter of the thermal bridge element 4 dwb is 1 cm.

[0088] Figure 19 shows the temperature profile diagram 180 of the reactor 1 with a thermal bridge element 4 having a diameter of 1 ,5 cm and being arranged coaxially within the catalyst 2. The thermal bridge element 4 according to this embodiment is made of the same steel as the catalyst body structure 27 of the catalyst 2. It is visible that the maximum temperature reaches only ca. 365°C at ca. 1 cm in axial direction. The average temperature reaches only ca. 355°C at ca. 1 cm in axial direction. The coolant temperature Toi is 270°C, the ration between the maximum temperature to the average temperature Tv is 1 ,063 and the methane conversation rate YCH4 is 93,5435% and the outer diameter of the thermal bridge element 4 dwb is 1 ,5 cm. Figure 18 and Figure 19 show that a larger diameter of the thermal bridge element 4 does not automatically result in higher conversation rates, but it results in even lower temperatures.

[0089] Figure 20 shows the temperature profile diagram 190 of the reactor 1 with a thermal bridge element 4 having a diameter of 1 cm and being arranged coaxially within the catalyst 2. The thermal bridge element 4 according to this embodiment is made of the same steel as the catalyst body structure 27 of the catalyst 2. The thermal bridge element 4 extends beyond the inlet end 21 and the outlet end 25 by 10 cm. It is visible that the maximum temperature reaches only ca. 390°C at ca. 1 cm in axial direction. The average temperature reaches ca. 375°C at ca. 1 cm in axial direction. The coolant temperature Toi is 270°C, the ration between the maximum temperature to the average temperature Tv is 1 ,0951 and the methane conversation rate YCH4 is 95,716% and the outer diameter of the thermal bridge element 4 dwb is 1 cm.

[0090] Figure 21 shows the temperature profile diagram 200 of the reactor 1 with a thermal bridge element 4 having a diameter of 1 cm and being arranged coaxially within the catalyst 2. The thermal bridge element 4 according to this embodiment is made of the same steel as the catalyst body structure 27 of the catalyst 2. The thermal bridge element 4 comprises an opening having a diameter of 0,8 cm and a depth of 2,54 mm. It is visible that the maximum temperature reaches only ca. 400°C at ca. 1 cm in axial direction. The average temperature reaches ca. 375°C at ca. 1 cm in axial direction. The coolant temperature Toi is 270°C, the ration between the maximum temperature to the average temperature Tv is 1 ,11 and the methane conversation rate YCH4 is 95,716% and the outer diameter of the thermal bridge element 4 dwb is 1 cm.

[0091] Figure 22 shows the temperature profile diagram of the reactor 1 with a thermal bridge element 4 having a diameter of 1 cm and being arranged coaxially within the catalyst 2. The thermal bridge element 4 according to this embodiment is made of aluminum, which has a 20 times higher thermal conductivity compered to the steel of the catalyst body structure 27. It is visible that the maximum temperature reaches ca. 380°C at ca. 1 cm in axial direction. The average tempera- ture reaches ca. 370°C at ca. 1 cm in axial direction. The coolant temperature Toi is 270°C, the ration between the maximum temperature to the average temperature Tv is 1 ,0816 and the methane conversation rate YCH4 is 95301 % and the outer diameter of the thermal bridge element 4 dwb is 1 cm.

[0092] LIST OF DESIGNATIONS

[0093] 1 reactor 5 contact body

[0094] 11 reactor wall 6 cooling wall

[0095] 2 structured fixed-bed catalyst 61 cooling channel

[0096] 21 inlet end 25 100 first 3D temperature diagram

[0097] 22 inlet section 110 second 3D temperature dia¬

[0098] 23 middle section gram

[0099] 24 outlet section 120 third 3D temperature diagram

[0100] 25 outlet end 130 first sensitivity diagram

[0101] 26 catalyst wall 30 140 second sensitivity diagram

[0102] 27 catalyst body structure 150 first 2D temperature diagram

[0103] 28 catalyst coating 160 second 2D temperature dia¬

[0104] 29 catalyst body wall gram

[0105] 31 ,32,33 catalyst channels 170 third 2D temperature diagram

[0106] 4 thermal bridge element 35 180 fourth 2D temperature dia¬

[0107] 41 main body of thermal bridge gram element 190 fifth 2D temperature diagram

[0108] 42 lateral protrusion of thermal 200 sixth 2D temperature diagram bridge element 210 seventh 2D temperature dia-

[0109] 43 opening in the thermal bridge 40 gram element L longitudinal axis

Claims

PATENT CLAIMS1. Reactor (1 ) for synthesis in particular of methane and / or methanol in an exothermic reaction, the reactor (1 ) extending along a longitudinal axis (L) and comprising: a. a structured fixed-bed catalyst (2) extending along the longitudinal axis (L) from an inlet end (21 ) to an outlet end (25) and comprising a plurality of adjacently arranged channels (31 , 32, 33) extending from the inlet end (21 ) to the outlet end (25); b. a thermal bridge element (4) arranged at least partially within the structured fixed-bed catalyst (2), wherein the thermal bridge element (4) is thermally conductively connected to the structured fixed- bed catalyst (2) and extends along the longitudinal axis (L) from an inlet section (22) of the structured fixed-bed catalyst (2) to a downstream section (23, 24) of the structured fixed-bed catalyst (2), thereby transferring at least some reaction heat generated in the inlet section (22) during operation of the reactor (1 ) away from the inlet section (22).

2. Reactor (1 ) according to claim 1 , wherein the thermal bridge element extends along the longitudinal axis (L) from the inlet section (22) of the structured fixed-bed catalyst (2) to an outlet section (24) of the structured fixed- bed catalyst (2), thereby transferring at least some reaction heat generatedin the inlet section (22) during operation of the reactor (1 ) from the inlet section (22) to the outlet section (24).

3. Reactor (1 ) according to any one of the preceding claims, wherein the thermal bridge element (4) has a rod shape or a cylinder shape, in particular a circular cylinder shape, extending parallel with respect to the longitudinal axis (L).

4. Reactor (1 ) according to any one of the preceding claims, wherein a maximal radial extension of the thermal bridge element (4) is at least 50% larger, preferably at least 200% larger, more preferably at least 400% larger than a wall thickness of a catalyst wall (26) separating at least two channels of the structured fixed-bed catalyst (2).

5. Reactor (1 ) according to any one of the preceding claims, wherein the thermal bridge element (4) has a thermal conductivity equal to or greater than the thermal conductivity of the structured fixed-bed catalyst (2).

6. Reactor (1 ) according to any one of the preceding claims, wherein the thermal bridge element (4) has a thermal conductivity of at least 5 W / mK, preferably of at least 10 W / mK, more preferably of at least 15 W / mK.

7. Reactor (1 ) according to any one of the preceding claims, wherein the reactor (1 ) comprises two or more thermal bridge elements (4) each being at least partially arranged within the structured fixed-bed catalyst (2).

8. Reactor (1 ) according to claim 7, wherein the two or more thermal bridge elements (4) are arranged uniformly within the structured fixed-bed catalyst (2) with respect to each other and with respect to the structured fixed-bed catalyst (2).

9. Reactor (1 ) according to any one of the preceding claims, wherein at the inlet end (21 ) of the structured fixed-bed catalyst (2) the thermal bridge element (4) protrudes from the structured fixed-bed catalyst (2).

10. Reactor (1 ) according to any one of the preceding claims, wherein a geometrical extension of the thermal bridge element (4) varies along its axial extension and I or wherein a material composition of the thermal bridge element (4) varies along its axial extension, thereby providing different heat transfer properties along its axial extension.1 1 . Reactor (1 ) according to any one of the preceding claims, wherein the thermal bridge element (4) comprises at least one opening, cavity or bore extending from one axial end into the thermal bridge element (4), the opening or bore being configured to affect the heat transfer properties along the axial extension of the thermal bridge element (4).

12. Reactor (1 ) according to any one of the preceding claims, wherein the thermal bridge element (4) comprises at least one lateral protrusion (42) extending at least partially radially from a longitudinal main body (41 ) of the thermal bridge element (4) into the structured fixed-bed catalyst (2).

13. Reactor (1 ) according to any one of the preceding claims, wherein the structured fixed-bed catalyst (2) includes a plurality of at least 100 channels, each extending from the inlet end (21 ) to the outlet end (25), each channel (31 , 32, 33) of the structured fixed-bed catalyst (2) preferably has a maximal radial extension from 0.2 mm to 5 mm, preferably from 0.3 mm to 3 mm.

14. Reactor (1 ) according to any one of the preceding claims, wherein the thermal bridge element (3), in particular its shape, its radial dimensions, its axial dimensions, its position within the structured fixed-bed catalyst (2) and / or its material composition, is selected based on an expected thermal profile of the reactor (1 ) during operation.

15. Method of synthesizing methane and / or methanol in an exothermic reaction, comprising providing the reactor (1 ) according to any one of claims 1 to 14 and reacting hydrogen with carbon dioxide, carbon monoxide or a mixture thereof in the reactor (1 ).

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