The present invention relates to cylindrical, solid shaped bodies of a catalyst as well as to a process for the syngas conversion to methanol and dimethyl ether and the use of said shaped bodies in said process.

Methanol (CH3OH) and dimethyl ether (DME) are important molecules with widespread applications for chemicals production and in the energy sector (e.g. as a substitute for gasoline or diesel fuels).

The standard way of producing methanol relies on the creation of a synthesis gas with a certain composition (comprising or consisting of H2, CO and CO2). The equations (1 ) to (5) below show the relevant reaction equations with the corresponding reaction enthalpies. Any CO/CO2 hydrogenation has a significant exothermic character, which have to be controlled and moderated.

(1 ) CO + 2H ₂ - CH3OH AH _r (g)= -90.5 kJ/mol

(2) CO ₂ + 3H ₂ - CH3OH + H ₂ O AH _r (g)= -49.3 kJ/mol

(3) 2 CH3OH CH3OCH3 + H ₂ O AH _r (g)= -23.9 kJ/mol

(4) 2CO + 4H ₂ - CH3OCH3 + H ₂ O AH _r (g)= -204.8 kJ/mol

(5) 2CO ₂ + 6H ₂ - CH3OCH3 + 3H ₂ O AH _r (g)= -122.5 kJ/mol

(6) CO2+H2 " CO + H ₂ O AH _r (g)= +41.2 kJ/mol

It is technically established that through a reactor in, e.g., the methanol synthesis, a significant temperature hotspot is formed. Exceeding a certain temperature leads to fast deactivation phenomena. Consequently, controlling this hotspot is very important to guarantee a long catalyst lifetime. One way of controlling the catalyst lifetime is its formulation, another way its geometric shape (besides the process conditions).

Further, these catalysts may also be used in the reverse water-gas shift reaction at much higher temperatures (350-600°C) compared to the CH3OH or DME synthesis (equ. 6).

The heat management for the methanol synthesis within the reactor, e.g., is discussed in Nitro- gen+Syngas 373, Sept-Oct 2021 (S. Osborne, H. Schwarz, S. Reitmeier) or in DE 10 2017 001 520 A1. Here, the temperature of the hotspot is regulated with catalysts of different activities and not with different shapes. The shapes are cylindric tablets having a circular base with different aspect ratios. WO 2020/120078 A1 describes a new shape with a dedicated hole structure for low pressure drop and high heat transport. However, since any boreholes decrease the stability of particle, it is preferred to provide shaped bodies without any hole-structure.

Another exemplary shape is described in WO 2012/110781 A1 , where a quadrilope shape is shown also having boreholes.

In ON 201404810 Y, a hole in a domed tablet shape is described, wherein the base form relates to a circle.

However, there is a need for further improved catalyst structures with advantageous heat transport and pressure-drop properties. These new shapes should allow a precise control of the hotspot (for exothermic reactions) or coldspot (for endothermic reactions) in the reactor and as consequence a longer lifetime or energetically more efficient processes.

Thus, an object of the present invention is to provide such catalyst shapes having the above properties or advantages.

The object is achieved by a cylindrical, solid shaped body of a catalyst, the cylinder having opposite bases, wherein the cylinder bases have an oval, non-circular form, the form being interrupted by at least one pair of opposite extensions or recesses in form of segments of a circle or an ellipse relative to a mirror plane of the cylinder perpendicular to the cylinder bases, wherein dimensions of the cylinder are defined by an enclosing cuboid box, the cuboid having a height xi and opposite square bases of the dimension X2 • X3 and in which the cylinder is positioned with the bases of the cylinder being part of the square bases and the mirror plane being parallel to the xi,X2-plane with the provisos that x ₂ < x ₃ < % X2 and Vi X2 < xi < 2 X2, and wherein one or more edges of the cylinder are optionally round off.

The object is also achieved by a catalytic reactor comprising a bed of cylindrical, solid shaped bodies of a catalyst of the present invention.

The object is also achieved by a process for the syngas conversion to methanol and dimethyl ether or reverse water-gas shift reaction comprising the step of passing syngas through a catalytic reactor of the present invention. In addition, the endothermic reverse reactions of equation (3) and (5), the reforming of MeOH and DME are of relevance. Here, a mixture of MeOH or DME with water is passed through the reactor and a hydrogen containing gas mixture is obtained.

The object is also achieved by the use of a cylindrical, solid shaped body of a catalyst of the present invention for the syngas conversion to methanol and dimethyl ether or reverse water- gas shift reaction. Surprisingly, it was found that due to the new catalyst shapes a precise control of the hotspot or coldspot in the reactor and as consequence a longer lifetime or energetically more efficient processes are is possible due to improved heat transport and pressure-drop properties. The new geometric shape influences the shape-fluid-interaction and results in significantly improved heat exchange and pressure drop properties.

The shaped body of a catalyst according to the present invention is a solid shaped body. The term "solid" means that the shaped body does not represent a hollow body. Accordingly, the solid body is free of a hollow space but can be porous or non-porous. Preferably, the shaped body is porous as this typically increases the active surface of the shaped body as catalyst.

The shaped body of a catalyst according to the present invention shows a cylindrical shape, i.e. is in form of a cylinder. The cylinder is characterized by two opposite bases, which are parallel to each other as usual for a cylindrical form without considering an optional rounding off. Such a rounding off typically results from the preparation process. It is also clear that the two opposite bases have an identical form. The two cylinder bases are enclosed by the cylinder jacket.

The cylinder bases of the shaped body of the present invention have an oval, non-circular form, wherein the form is interrupted by at least one pair of opposite extensions or recesses. The extensions or recesses have a form of a circular or ellipsoid segment and are located opposite to each other relative to a mirror plane of the cylinder perpendicular to the cylinder base (one of the bases). Both extensions I recesses of the pair have the same form so that the cylinder of the shaped body has two mirror planes, perpendicular to the cylinder bases and perpendicular to each other, i.e. a mirror plane parallel to the X2,X3-plane and a mirror plane parallel to the xi,X2- plane. The oval, non-circular form can show a third mirror plane parallel to the xi,X3 plane as it is the case for the higher ordered ellipse form, which is preferred.

Thus, the form of a base deviates from the oval form by one or more pairs of extensions or recesses, wherein extensions can be considered curvatures outwards and recesses can be considered as inward curvatures.

The dimensions of the cylinder of the shaped body of the present invention are defined by a smallest enclosing cuboid box. In general, a smallest enclosing box, also called minimum bounding box, in form of a cuboid, represents a cuboid with minimized dimensions in order to encompass one or more sets of points. According to the present invention, the cuboid represents the smallest box possible to encompass the cylinder, wherein the cylinder is positioned with the bases of the cylinder being part of the square bases of the cuboid and the mirror plane being parallel to the xi,X2-plane of the cuboid. Consequently, the height xi of the cuboid is identical to the height of the cylinder. The cuboid has a height xi and opposite square bases of the dimension X2 • X3, i.e. length X2 and breadth X3. The term “minimum” refers to the lowest possible volume of the cuboid. In order to provide optimized properties of the shaped body as described above, the following has to be fulfilled:

% X2 < X3 < % X2 and % x ₂ < Xi < 2 x ₂ .

Preferably, the following has to be fulfilled:

2/5 X2 < X3 < 2/3 X2 and 1/2 x ₂ < Xi < x ₂ .

More preferably, the following has to be fulfilled:

X3 = 1/2 x ₂ and 1/2 x ₂ < Xi < x ₂ .

One or more edges of the cylinder are optionally round off. This is mostly driven by the manufactory process. Rounding off can occur to an extent that outer faces can represent a domed form. For the geometry of the cylinder, the edge rounding off is not considered. By way of example, the bases of a cylinder in the mathematical sense are part of parallel planes, whereas the rounding off results in a curved geometry in case the borders of the cylinder bases are round off. Apart from the borders of the cylinder bases, also the cut lines of the recesses or extensions with the cylinder jacket can be round off.

Preferably, the cylindrical, solid shaped body of a catalyst according to the present invention has cylinder bases with an ellipsoidal form, the form being interrupted by the at least one pair of opposite extensions or recesses.

In a preferred embodiment, the form of the cylinder bases is interrupted by one, two, three, four or five pairs of opposite extensions. More preferably, the form of the cylinder bases is interrupted by one pair of opposite extensions.

In another preferred embodiment, the form of the cylinder bases is interrupted by one, two, three or four pairs of opposite recesses. More preferably, the form of the cylinder bases is interrupted by one pair of opposite recesses.

In a more preferred embodiment, the form of the cylinder bases is interrupted by one pair of opposite extensions and no recesses or the form of the cylinder bases is interrupted by one pair of opposite recesses and no extensions. More preferably, the form of the cylinder bases is interrupted by one pair of opposite extensions and no recesses.

Preferably, xi is in the range of from 2 mm to 20 mm. More preferably, xi is in the range of from 3 mm to 8 mm. Even more preferably, xi is in the range of from 3.25 mm to 7.5 mm.

Preferably, x ₂ is in the range of from 4 mm to 10 mm. More preferably, x ₂ is in the range of from 6 mm to 8 mm. Even more preferably, x ₂ is in the range of from 6.5 mm to 7.5 mm. Preferably, X3 is in the range of from 1 mm to 7.5 mm. More preferably, X3 is in the range of from 2.4 mm to 5.33 mm. Even more preferably, X3 is in the range of from 3.25 mm to 3.75 mm.

An exemplary dimension is xi = 4 mm, X2 = 7 mm and X3 = 3.5 mm. Another exemplary dimension is xi = 5 mm, X2 = 7 mm and X3 = 3.5 mm. Another exemplary dimension is xi = 6 mm, X2 = 7 mm and X3 = 3.5 mm.

Preferably, the percentage of the total area of the at least one pair of opposite extensions or recesses based on the area of the cylinder base is in the range of from >0 % to 20 %, more preferably from 5 % to 17.5 %, even more preferably from 10 % to 15 %.

Preferably, the shaped body is free of holes. The term “hole” means any hole in the shaped body regardless it is a resulting of the preparation process of the shaped body or introduced afterwards. An exemplary hole prepared afterwards is a borehole produced by drilling.

Preferably, one or more edges of the cylinder are round off.

Preferably, the catalyst of the cylindrical, solid shaped body of a catalyst of according to the present invention catalyses syngas conversion to methanol and dimethyl ether or reverse water- gas shift reaction.

Accordingly, another aspect of the present invention is a catalytic reactor comprising a bed of cylindrical, solid shaped bodies of a catalyst according to the present invention.

Accordingly, another aspect of the present invention is a process for the syngas conversion to methanol and dimethyl ether or reverse water-gas shift reaction comprising the step of passing syngas through a catalytic reactor of the present invention.

Accordingly, another aspect of the present invention is the use of a cylindrical, solid shaped body of a catalyst according to the present invention for the syngas conversion to methanol and dimethyl ether or reverse water-gas shift reaction.

The catalysts, catalytic reactors and their use in processes are well known to the practitioner in the art. The same applies to the manufacture of shaped bodies according to the present invention. An exemplary syngas reaction is described in DE 10 2017 001 520 A1.

A typical process for the manufacture of catalyst shaped bodies is via extrusion. This results in substantially constant cross-sectional form along their length and substantially flat end surfaces. Brief description of the drawings

Fig. 1 shows a non-inventive shaped body with drawn smallest enclosing box;

Fig. 2 shows an inventive shaped body with five pairs of extensions and four pairs of recesses in 3D form, where the border of the base is not round off (Fig. 2a) and the form where all edges are round off (Fig. 2b) and the respective base form (Fig. 2c) indicating the circular segments of recesses and extensions and the areas (Fig. 2d);

Fig. 3 shows an inventive shaped body with one pair of extensions in 3D form (Fig. 3a) and the respective base form (Fig. 3b) indicating the circular segments of extensions and the areas (Fig. 3c);

Fig. 4 shows an inventive shaped body with one pair of recesses in 3D form (Fig. 4a) and the respective base form (Fig. 4b) indicating the circular segments of recesses and the areas (Fig. 4c).

Fig. 5 shows a graph of relative pressure drop delta p as a function of the relative Nu-number.

Detailed description of the drawings

Fig. 1 shows a non-inventive shaped body in form of a cylinder (1 ) with an upper base (2) and a (partly shown) cylinder jacket (3) missing any recesses and extensions. In Fig. 1 , also the smallest enclosing cuboid box (4) is drawn having a height xi, a length X2 and a breadth X3. The upper base (2) of the cylinder (1 ) is part of the square base (5) of the box (4). In addition, the mirror plane, comprising the most distal points of the oval form, perpendicular to the base (x ₂ ,x ₃ ) is parallel to the xi,X2-plane.

Fig. 2a shows a cylinder (1) with five pairs of extensions (6) and four pairs of recesses (7) in 3D form, where the border of the cylinder bases (2) are not round off (Fig. 2a) Fig. 2b shows a shaped body of Fig. 2a in 3D, where all edges are round off.

Fig. 2c shows a cylinder base (2) of a shaped body of Fig. 2a having an approximate oval form (9) with five pairs of extensions (6) and four pairs of recesses (7) in form of circular segments. The respective pairs of extensions (6) and recesses (7) are opposite to each other relative to a mirror plane perpendicular to the base (2) along the cutting line (9).

Fig. 2d shows the areas (in mm ² ) of the cylinder base AF, the oval form AO, extensions A1 and recesses A2 of the cylinder of Fig. 2a. The total area of extensions is ZA1 = 2*(2*0.031971 + 2*0.048462 + 0.0869392) = 0.494516. The total area of recesses is ZA2 = 8*0.048462 = 0.387696. A0 = 16.379 and AF is 16.486. The percentage of the total area of the at least one pair of opposite extensions or recesses based on the area of the cylinder base is (ZA1 + ZA2)/AF = 5%. Fig. 3a shows a cylinder (1) with a cylinder base (2) having one pair of extensions (6). Fig 3b shows a cylinder base (2) of a shaped body of Fig. 3a having an oval form (9) as ellipse and a pair of extensions (6) in form of circular segments, wherein the extensions (6) are opposite to each other relative to a mirror plane perpendicular to the base (2) along the cutting line (9). Round off (10) of edges is also shown.

Fig. 3c shows the areas (in mm ² ) of the cylinder base AF, the oval form A0, extensions A1 of the cylinder of Fig. 3a. The total area of extensions is ZA1 = 2*0.9165 = 1 .833. A0 = 13.774 and AF is 15.607. The percentage of the total area of the at least one pair of opposite extensions or recesses based on the area of the cylinder base is (ZA1 + ZA2)/AF = 12 %.

Fig. 4a shows a cylinder (1) with a cylinder base (2) having one pair of recesses (7). Fig 3b shows a cylinder base (2) of a shaped body of Fig. 4a having an oval form (8) as ellipse and a pair of recesses (7) in form of circular segments, wherein the recesses (7) are opposite to each other relative to a mirror plane perpendicular to the base (2) along the cutting line (9).

Fig. 4c shows the areas (in mm ² ) of the cylinder base AF, the oval form A0, recesses A2 of the cylinder of Fig. 4a. The total area of recesses is ZA2 = 2*1 .1015 = 2.203. A0 = 19.381 and AF is 17.178. The percentage of the total area of the at least one pair of opposite extensions or recesses based on the area of the cylinder base is (ZA1 + ZA2)/AF = 13 %.

Fig. 5 shows a graph of relative pressure drop delta p as a function of the relative Nu-number for a shaped body according to Fig. 2a (“w1”), according to Fig. 2b (“w1”), according to Fig. 3a (“n2”) and according to Fig. 4a (“c1”). The data points result from simulations further described in the examples.

Examples

Simulations were carried out as described in the examples of EP 3431 178 A1 . The respective computer-implemented method is further described in WO 2021/105277 A1 .

Shaped bodies used in the following are as follows: a shaped body according to Fig. 2a (“w1”), according to Fig. 2b (“w1”), according to Fig. 3a (“n2”) and according to Fig. 4a (“c1”).

All shaped bodies have dimensions xi = 4 mm, X2 = 7 mm, X3 = 3.5 mm.

Definition of the used measures and reference cases

• Reference case (ref): cylinder (D = 6 mm x H = 4 mm) in representative reactor tube

• Reynolds number: Re p-vd o Re = - - n • Pressure drop: Ap [Pa/m]

• Load density (catalyst mass per reactor volume (V)): LD [kg/l] o relative LD = ^LD D-ref

• Specific surface (catalyst surface area (A) per reactor volume (V)): A/V [1/m]:

• Global Nusselt number (dimensionless heat transfer coefficient): Nu o By using a constant length (d) and a constant thermal conductivity (A) to calculate the Nusselt number (Nu), Nu is proportional to the heat transfer coefficient (a). Therefore, this Nu-number can be used to rank the shapes by the global heat transfer from the wall into the fluid. o By its global definition, the Nusselt number includes the heat transfer coefficient at the wall as well as radial heat transport within the packed bed.

The geometric surface area (GSA or A/V), porosity or load density (LD), pressure drop (Ap) and thermal transport (Nu) for a packed bed of arbitrary shaped catalysts were determined. The values are obtained from a detailed numerical simulation. First, the geometry of the bed is created. For this purpose, a CAD (Computer Aided Design) model of a single shaped catalyst body is created with any CAD program. A random packing of the respective shape is generated with a simulation using the real geometry of a reactor or a representative section of a reactor and the catalyst. The packing is generated by virtually dropping the catalyst particles into the reactor geometry and calculating the movement and impacts between particle-particle and particle-wall contacts according to Newton’s second law of motion. A DEM algorithm is used as numerical method. The geometric surface area and the porosity are directly derived from the virtually created packed bed. The pressure drop and the thermal transport are results of a detailed simulation applying computational fluid dynamics. The fluid volume is extracted from the numerically generated random packed bed. The fluid dynamics around each pellet as well as all interstitial flow phenomena are fully resolved. The pressure drop is then calculated for a representative bed height and the reactor geometry. Compressed air is used as fluid. The pressure at the end of the packed bed is ambient pressure. Temperature is set to ambient temperature. The applied flow rate is varied to cover a broad Reynolds number range. The reference length used to calculate the Reynolds number is defined as 0.01 meters. The thermal transport is included in the fluid dynamic simulation by applying a fixed temperature as boundary condition of the reactor wall. The temperature of the wall is set 100 K above the temperature of the fluid at the reactor inlet. As KPI for the thermal transport a global Nusselt number is calculated from the thermal boundary conditions at the inlet and the reactor wall and the resulting mass weighted temperature at the outlet of the representative simulation. According to Fig. 5 all exemplified shaped bodies of the present invention show at least better relative Nu-numbers compared to the reference. Shaped bodies w1 and n2 show in addition better values for delta p with n2 having the best performance.