Amino-functionalized molded bodies with partially loaded pore volume

Abstract

The invention relates to a sorbent for CO2, comprising a molded body (i) made of at least one metal oxide; and at least one amine-based sorption agent (ii) for CO2, the molded body (i) being partially loaded with the sorption agent, wherein the molded body has a porous structure with a total pore volume PVo, and the process of partially loading the molded body (i) with the at least one sorption agent (ii) is characterized in that 40-70% of PVo is loaded with the sorption agent. The invention also relates to the production of said sorbent and to the use thereof as a fixed-bed sorbent in the chemisorption of CO2.

Description

[0001] Amino-functionalized molded bodies with partial filling of the pore volume

[0002] The present invention relates to a sorbent for CO2, comprising a shaped body (i) made of at least one metal oxide; and at least one amine-based sorbent (ii) for CO2, with which the shaped body (i) is partially loaded, wherein the shaped body has a porous structure with a total pore volume PVo, wherein the partial loading of the shaped body (i) with the at least one sorbent (ii) is characterized in that 40-70% of PVo is loaded with the sorbent, the production of this sorbent, and the use of this sorbent as a fixed-bed sorbent in the chemisorption of CO2.

[0003] Climate change and global warming are considered the most serious environmental problems of our time. It is now widely accepted that the main cause of global warming is the release of so-called greenhouse gases into the atmosphere. One important greenhouse gas is carbon dioxide (CO2), which is released primarily during the combustion of fossil fuels such as coal, oil, and natural gas. Together, these fossil fuels cover about 80% of global energy demand. Since fossil fuels are still relatively inexpensive and easy to use, and no satisfactory alternatives are yet available that could replace them to the necessary extent, fossil fuels are expected to remain our most important energy source in the long term. This makes it all the more important to channel CO2 emissions into innovative technologies capable of storing CO2 as a valuable resource and / or using it as a feedstock for further processes.“Carbon Capture and Storage” (CCS) is a representative of such technologies, in which CO2 is captured either from the environment or directly at the sources of fossil CO2 emissions of an industrial or energy-related nature, processed, compressed and transported to a storage site.

[0004] In contrast to the pure storage purpose of CCS, “Carbon Capture and Utilization” (CCU) concerns the capture of CO2, especially from combustion exhaust gases, and its subsequent use in further chemical processes, such as the conversion to methanol.

[0005] Another method for obtaining CO2 is "Direct air capture" (DAC), in which CO2 is extracted from the ambient air.

[0006] All these technologies require that CO2 can be (reversibly) sorbed onto a solid sorbent. This sorbent is typically used as a fixed-bed sorbent in sorption columns, through which the gas from which CO2 is to be removed flows.

[0007] In the prior art, solid sorbent materials are currently used in the form of finely divided powders, which, however, have disadvantages for sorption columns. The use of finely divided powders in the columns leads to an undesirably high pressure drop, accompanied by turbulence and the discharge of the sorbent from the column.

[0008] Instead of using finely divided powders, EP2102131A1 teaches the use of larger metal oxide bodies, which, however, are not functionalized and therefore unsuitable for selectively adsorbing CO2 from gas mixtures. Methods for producing stable metal oxide bodies are also described in WO 2008 / 071611 Al and WO 2008 / 071612 Al. In these methods, an aqueous dispersion of the metal oxide is prepared, which is then made more solid by the addition of a coagulant. The coagulant is a basic salt that decomposes below the sintering temperature and does not melt. Coagulation is initiated by increasing the pH value. This solidified mass is then shaped, for example, by extrusion. The resulting green bodies are dried and subsequently sintered to strengthen the substrates.However, for the reliable use of these molded bodies in sorption columns with low pressure drop and little turbulence, the strength should be further increased.

[0009] It would therefore be desirable to provide a CO2 sorbent that overcomes the disadvantages associated with powdered sorbent materials, i.e., one that exhibits high strength when used as a fixed-bed sorbent in a sorption column, as well as resulting in low pressure drop and minimal turbulence or even carry-out of the sorbent from the column. At the same time, CO2 should be reversibly bound with high sorption efficiency and capacity.

[0010] The problem according to the invention is solved by the first aspect of the present invention, namely a sorbent for CO2, in particular a solid sorbent, comprising

[0011] (i) a shaped body (i) made of at least one metal oxide;

[0012] and (ii) at least one amine-based sorbent (ii) for CO₂ with which the molded body (i) is partially loaded,

[0013] wherein the molded body has a porous structure with a total pore volume PVo,

[0014] wherein the partial loading of the molded body (i) with the at least one sorbent (ii) is characterized in that 40-70% of PV₀ are loaded with the sorbent.

[0015] “Loading” (also called “functionalizing”) within the meaning of the invention means, for example, that the molded body (i) is impregnated and / or coated with the sorbent (ii).

[0016] “Partial loading” within the meaning of the invention means that not the entire pore volume PVo of the solid is functionalized with the sorbent of volume Vs, but only a proportion, according to the invention in a range of 40-70% of PVo.

[0017] Essential for the sorbent materials according to the invention is their ability to bind CO2. This is achieved by the amine groups of the sorbent (ii), which, for example, form ammonium carbamates with CO2. CO2 is thus bound by chemisorption. To maximize the adsorption capacity of the sorbent, a high amine density is therefore desirable. It is thus logical to fill the maximum available pore volume PVo of the molded body with the amine-based sorbent. Surprisingly, however, it has been shown that homogeneous loading of the molded body with the amine-based sorbent and a maximized adsorption capacity for CO2 are only achieved if the molded body is partially loaded with the sorbent within the limits of the invention.

[0018] Before loading with the sorbent, the molded body has a total pore volume PVo. During loading, the molded body, and in particular the interior of the pores, becomes functionalized with the sorbent, resulting in a pore volume PVB measured after loading that is less than PVo. The loading according to the invention of 40-70% of the initial pore volume PVo of the molded body is thus a measure of what proportion of the originally accessible pore volume is filled with amine-based sorbent.

[0019] The pore volume of the molded body or the sorbent for CO₂ can be determined using methods known in the field, for example by mercury porosimetry, for example according to ISO 15901-1.

[0020] The loading is preferably determined according to the following equation ( I ):

[0021] / PVB \

[0022] Load = I 1 - — ) ■ 100% (I)

[0023] where PV BThe pore volume measured after loading in mL / g, PV0 the total pore volume of the initial mold body in mL / g, and ω the dimensionless mass fraction of SiO₂ in the total mass of the sorbent.

[0024] ω can be easily determined, for example, using elemental analysis techniques. In practice, the nitrogen content of the sorbent is usually determined by elemental analysis, whereby the mass fraction of SiO₂ can be derived taking into account the known composition of the sorbent (e.g., the type of amine-based sorbent). This factor ω determines PV B corrected for nitrogen content.

[0025] PV0 is preferably at least 0.5 mL / g, more preferably 0.5-3.0 mL / g, more preferably 0.6-2.0 mL / g, in particular 0.8-1.5 mL / g.

[0026] PV B preferably at least 0.1 mL / g, more preferably 0.1-2.0 mL / g, more preferably 0.2-1.5 mL / g, in particular 0.2-0.5 mL / g.

[0027] ω is preferably 0.4-0.9, in particular 0.5-0.8.

[0028] The loading (or impregnation) of the molded body preferably involves a non-covalent coating (functionalization) of the pore surface of the molded body with the at least one sorbent, such that a maximization of the CCt binding capacity is expected with increasing surface area (inside, i.e., within the pores, and outside) of the molded bodies used, defined as the specific surface area (SSA). Surprisingly, however, the pore volume of the molded bodies, and not the SSA, represents a crucial property characteristic for increasing the CCt binding capacity and for homogeneous impregnation of the substrate materials.

[0029] Surprisingly, the partial loading of 40–70% of PVo with the sorbent according to the invention leads to maximized CO2 binding capacities. If the loading falls below or exceeds the limits according to the invention, a significant drop in the CCt binding capacities is observed, as impressively demonstrated in the examples. The desired loading of the molded body in % of PVo is preferably achieved by coating the molded body with a volume of the pure sorbent V. s functionalized (for example by means of pseudo-IWM or IWM, see below), which corresponds at least to the desired proportion of the total pore volume (based on a specific weight of the molded body).

[0030] The calculation of the volumes Vs of the sorbent used for loading refers to volumes under standard reaction conditions, i.e. 25 °C and 1013 hPa.

[0031] According to the invention, the lower limit of the load is at least 40% of PVo and the upper limit of the load is at most 70% of PVo.

[0032] The loading of the molded body can be quantitative, meaning the entire volume Vs is used to functionalize the PVo. However, an excess of Vs may be necessary, as not all of the added volume Vs leads to the functionalization of the PVo. To still achieve the desired loading values, it is therefore advantageous to use Vs in a slight excess. In this context, it is particularly advantageous to use Vs in an excess of up to 15 vol.%, especially 15 vol.%.

[0033] The lower limit of the loading according to the invention is achieved by molding the body with a volume V s functionalized, which corresponds to at least 40%, in particular at least 55% of PVo (based on a specific weight of the molded body).

[0034] The upper limit of the load according to the invention is reached by molding the body with a volume V s functionalized, which corresponds to at most 85%, in particular at most 70% of PVo (based on a specific weight of the molded body).

[0035] A loading of at least 40% and at most 70% of PVo can be achieved by molding the body with a volume V s functionalized, which corresponds to at least 40% and at most 85% of PVo, in particular at least 55% and at most 85% of PVo (based on a specific weight of the molded body).

[0036] The sorbents according to the invention are characterized in particular by a high adsorption efficiency AE. The AE is a measure of what proportion of the total available nitrogen is available for the adsorption of CO2 and is calculated according to the following formula ( II ).

[0037] AE = AK / γ · 2 · 100 % (II)

[0038]

[0039] AK presents C02 The adsorption capacity of the sorbent for CO2 in mmol / g is represented, which can be determined as shown in the examples. y represents the proportion of nitrogen in the total mass of the sorbent in mmol / g and can be easily determined, for example, by elemental analysis. The factor 2 represents a correction factor that takes into account the molar ratio of chemisorption. According to the following reaction equation, 2 moles of nitrogen can bind 1 mole of CO2.

[0040]

[0041] AE is preferably at least 35%. AK C02 preferably at least 1.0 mmol / g sorbent.

[0042] Y is preferably at least 4.0 mmol / g sorbent, in particular 4.0 - 11.0 mmol / g sorbent.

[0043] The shaped bodies have a pore size in the range of 10-80 nm, preferably 18-55 nm, particularly before functionalization with the sorbent.

[0044] The pore size refers to the diameter of the pores in the shaped body and can be determined using methods known in the field, such as mercury porosimetry.

[0045] In a preferred embodiment, the partial loading is 40-65% of PVo for molded bodies with an average pore size of less than 50 nm, in particular less than 25 nm, and 40-70% of PVo for molded bodies with an average pore size of 50 nm or more, in particular 55 nm and more.

[0046] In a preferred embodiment, the at least one metal oxide is selected from aluminum oxide, silicon dioxide (also referred to as silica), titanium dioxide, or zirconium dioxide, preferably from silicon dioxide, and in particular from amorphous silicon dioxide. The amorphous silicon dioxide is particularly preferably selected from pyrogenic or precipitated silicon dioxide, and in particular from pyrogenic silicon dioxide.

[0047] To produce pyrogenic silicon dioxide, a volatile silicon halide (e.g., silicon tetrachloride) is usually injected into an oxyhydrogen flame of hydrogen and air. This substance hydrolyzes to silicon dioxide under the influence of the water produced during the oxyhydrogen reaction. After leaving the flame, the silicon dioxide enters a so-called coagulation zone, where the primary particles and primary aggregates agglomerate.

[0048] To produce precipitated silica, for example, commercially available sodium silicate is reacted with acid (e.g., sulfuric acid) at a pH between 7.5 and 10.5. The pH is then adjusted to 3.0 to 5.0, and the precipitated silica is filtered, washed, and dried.

[0049] A preferred sorbent comprises shaped bodies having dimensions in one, two or three dimensions, more preferably in two or three dimensions, particularly in all three dimensions in the range of 0.5 mm to 30 mm, preferably 1.0 mm to 15 mm.

[0050] Preferably, the sorbent according to the invention has the same dimensions as the corresponding molded body.

[0051] When a gas mixture flows through powder beds known in the prior art, a high pressure drop occurs between the sides facing the gas source and those facing away from it. A coarser shaped body having the dimensions according to the invention is advantageous because the pressure loss (= pressure drop) when flowing through such a bed is reduced.

[0052] The sorbent according to the invention is therefore particularly well suited as an efficient fixed-bed sorbent for CCU, CCS, or DAC, since—in contrast to finely divided powders—it results in a lower pressure drop and minimal turbulence or even carryover of the sorbent from the sorption column. Efficient CO2 adsorption is only possible using the shaped bodies according to the invention. Furthermore, the shaped bodies according to the invention exhibit improved mechanical stability and improved long-term stability. Unlike powdered sorbents, the shaped bodies according to the invention do not tend to agglomerate or clump together when impregnated (functionalized with sorbent) and do not require complex milling.

[0053] Surprisingly, it has been shown that particularly good adsorption efficiencies in the sorption column can only be achieved if the mechanical properties (compressive strength) of the sorbent according to the invention are maintained.

[0054] It is preferred that the sorbent has a compressive strength of at least 2 N / mm². 2 , preferably at least 8 N / mm 2 , exhibits.

[0055] The compressive strength according to the invention can be determined using all methods known in the field, for example with the aid of a material testing machine, such as the Texture Analyser XT plus from Winopal.

[0056] In a particular embodiment, the shaped bodies are essentially spheres, ellipsoids, cylinders, hollow cylinders (e.g., tubes), wagon wheels, honeycombs, or cuboids, preferably cylinders or hollow cylinders. It is also clear to those skilled in the art that the specified geometry does not represent perfect geometric bodies, so deviations from the ideal geometry are possible.

[0057] The molded parts preferably have an aspect ratio of at most 15, more preferably at most 10, and most preferably at most 6. It has also been found that this aspect ratio has a particularly positive effect on the suitability of the molded part in a sorption column, since the already low pressure drop when using the molded parts according to the invention can be further reduced due to this aspect ratio. Molded parts whose aspect ratio exceeds that of the invention are no longer practical to pack in reaction / sorption columns and tend to break. Fractures are disadvantageous because they result in very small fragments of the molded part, which cause a high pressure drop and turbulence in the column, as well as discharge from the column.

[0058] The molded body is preferably composed of agglomerates of amorphous silicon dioxide / silica. The agglomerates are preferably composed of aggregates of a plurality of primary silica particles.

[0059] In a preferred embodiment, the BET surface area of ​​the sorbent is in the range of 30 to 500 m². 2 / g, especially in the range of 50 to 400 m 2 / G.

[0060] The BET surface area can be determined using established measurement methods. The BET surface area is preferably determined using nitrogen in accordance with DIN 66131.

[0061] Preferably, the molded bodies are characterized by a high pore volume PV0, which is at least 0.5 mL / g, more preferably 0.5-3.0 mL / g, more preferably 0.6-2.0 mL / g, in particular 0.8-1.5 mL / g.

[0062] These high pore volumes give the sorbent according to the invention the advantage that it can be functionalized with a particularly large amount of sorbent, which significantly increases the sorption capacity for CO2.

[0063] If the pore volume exceeds the ranges mentioned above, the molded bodies are too fragile and tend to break when used in a sorption column. This results in the formation of very small molded body fragments and thus a high pressure drop. Fragments with a smaller pore volume than specified have too small an internal surface area and therefore lead to low sorption efficiencies and capacities.

[0064] The determination of the pore volume and pore size is carried out using methods known in the field, for example by means of Hg porosimetry, for example as described in ISO 15901-1.

[0065] In a preferred embodiment, the metal oxide of the molded body, in particular the silicon dioxide of the molded body, has a mesoporous structure, in particular a mesoporous structure with an irregular pore structure.

[0066] The irregular pore structure of the silica according to the preferred embodiment above is retained in the molded body. The pore structure of the silica forms channels within the molded body, which define its inner surface.

[0067] The functionalization with the sorbent is preferably located on the inner surfaces of the molded bodies according to the invention.

[0068] Mesoporous solids, according to the IUPAC definition, are porous materials with pore diameters between 2 nm and 50 nm. It is known to those skilled in the art that mesoporous silica is typically produced by a complex template-based synthesis. Silica produced in this way is characterized by a defined, channel-like pore structure. In contrast, the shaped bodies according to the invention are based on silica, which is characterized by an irregular pore structure. In this context, "irregular pore structure" means that the pores within the silica extend asymmetrically and / or randomly, either with or without at least one branch and / or division, without any discernible repeating segments.

[0069] Silica with such an irregular pore structure offers economic advantages, for example, as it is far cheaper and easier to produce than silica with a predefined and regular channel structure. Surprisingly, it has also been shown that the CO2 adsorption efficiency of the silica molded bodies according to the invention with an irregular pore structure can significantly exceed the adsorption efficiency of silica molded bodies with a defined, uniform pore structure, since silica with an irregular pore structure is less prone to clogging and blockage of the channels by sorbents. Thus, the inner surfaces of the molded bodies according to the invention can be more homogeneous and completely functionalized, thereby increasing the adsorption capacity (also called binding capacity) of the molded bodies according to the invention for CO2.Sufficient capacities for efficient CO2 sorption are preferably at least 1.4 mmol / g, more preferably at least 2.2 mmol CO2 per gram of sorbent, and even more preferably at least 4.4 mmol CO2 per gram of sorbent. In a preferred embodiment, the at least one sorbent (ii) is capable of undergoing a reversible reaction with CO2, in particular a reversible sorption reaction.

[0070] The sorption reaction is specifically a chemisorption. In this case, the CO2 is bound to the inner surface of the molded part by chemical bonding with the sorbent. By increasing the temperature and / or decreasing the pressure, the chemisorbed CO2 can be released from the molded part and thus driven off. This has the advantage that the CO2 can not only be removed from the gas phase (e.g., DAC, CCS), but can also be released again at any later time and, for example, fed into a process where CO2 serves as a feedstock (e.g., CCU), such as the conversion to methanol.

[0071] In a preferred embodiment, the molded body is sintered at a sintering temperature Ts, which is preferably in a range of 800-1200 °C, particularly in a range of 900-1100 °C.

[0072] In the context of the present invention, sintering refers to the treatment of a green body (an easily machinable blank) formed, for example, by extrusion, in order to transform it into a solid finished body. The green body can sometimes be dried at lower temperatures before sintering.

[0073] The at least one sorbent (ii) may be an organic sorbent based on amines.

[0074] The organic sorbent based on amines (ii) may be an organic monoamine or polyamine, wherein the polyamine comprises at least two N atoms per molecule separated by at least one C atom, in particular selected from the group consisting of ethyleneamine, aminosilane, polyethyleneimine (PEI), polypropyleneamine, polyvinylpyridine, polydimethylaminoethyl methacrylate, polyamidoamine, polyvinylamine and polyallylamine.

[0075] The ethyleneamine is preferably selected from the group consisting of ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetraamine (TETA), tetraethylenepentamine (TEPA), aminoethylethanolamine (AEEA), aminoethylpiperazine (AEP), piperazine (PIP), hydroxyethylpiperazine (HEP), pentaethylenehexamine (PEHA) and polyethylenepolyamine (PEPA).

[0076] The aminosilane is preferably selected from the group consisting of aminopropylsilane, [3-(2-Aminoethylamino)-propyl]-trialkoxysilane, 3-[2-(2-Aminoethylamino)-ethylamino]-propyltrialkoxysilane, mixtures thereof and condensation products of 3-aminopropyltrialkoxysilane.

[0077] The polyamine can be silylated, for example obtained by reacting one or more amino groups of the polyamine with suitably functionalized alkoxysilanes, for example selected from the group consisting of 3-chloropropyl-trialkoxysilane, 3-chloropropyl-trialkoxysilane, glycidoxypropyl-trialkoxysilane and isocyanatopropyl-trialkoxysilane.

[0078] For the purposes of this application, ‘alkoxy group’ preferably means a C1 to C4 alkoxy group, in particular preferably an ethoxy or methoxy group.

[0079] The silylated polyamine can be obtained by silylation, which is carried out either in isolation or in situ. In a preferred embodiment, the sorbent according to the invention further comprises

[0080] (iii) at least one auxiliary substance (iii) selected from the group consisting of polymeric binders, silicon-containing binders such as silicates and silica sol, spreading agents and wetting agents.

[0081] The polyamine can be present in combination with at least one amino-functional alkoxysilane.

[0082] The at least one amino-functional alkoxysilane is preferably selected from the group consisting of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane and 3-aminopropyltriisoproxysilane.

[0083] In a special version, the molded body of the sorbent is free of inorganic and organic chemical binders, such as glycerin, kaolin, sugar, starch, urea, wax, methylcellulose, magnesium stearate, graphite, aluminum stearate, polyethylene glycol or polyethylene oxide.

[0084] It is particularly advantageous that the sorbent has a proportion of flaking material of less than 5 wt.%, preferably less than 1 wt.% and most preferably less than 0.5 wt.% based on the total weight of the sorbent.

[0085] Another aspect of the present invention relates to a method for producing the sorbent according to the invention for CO2, comprising the following steps in the specified order: (A) providing a shaped body (i) made of at least one metal oxide (M); and

[0086] (B) Impregnating the provided molded body with at least one amine-based sorbent (ii) for CO2 in order to partially load the molded body with it (also referred to as functionalizing).

[0087] In a preferred embodiment, the provision of the molded body in step (A) is carried out by the following steps in the specified order:

[0088] (Al ) Providing a metal oxide dispersion by dispersing at least one metal oxide (M) in a dispersing agent;

[0089] (A2) Coagulation of the dispersion by raising the pH value;

[0090] (A3) Shaping the coagulated dispersion to produce a green body; and

[0091] (A4) Drying and subsequent sintering of the green body at a sintering temperature T s , in order to produce the sintered molded body.

[0092] In the process according to the invention, a metal oxide dispersion is therefore first produced in the first step (Al ).

[0093] This dispersion is coagulated in a subsequent step (A2).

[0094] In the next step (A3), the coagulated dispersion can be transferred into a mold, yielding a green body, i.e., a shaped blank from the coagulated dispersion. This green body is then transformed into a sintered shaped body by drying and sintering according to step (A4). Only then does the shaped body acquire the mechanical stability required for use in sorption columns.

[0095] The proportion of the at least one metal oxide in the metal oxide dispersion of step (Al ) can be 10-50 wt. -%, preferably 20-40 wt. -%, based on the total mass of the dispersion.

[0096] In a preferred method, the provision of the metal oxide dispersion in step (Al) is carried out by stirring in the at least one metal oxide using a dissolver disc and a butterfly insert simultaneously.

[0097] The mixer used is therefore preferably equipped with a dissolver disc and a butterfly insert.

[0098] A dissolver disc is a stirring disc mounted in a mixer, rotatable around an axis, and immersed in the product to be dispersed. When the disc rotates, shear forces are generated that break down the product to be dispersed (in this case, at least one metal oxide).

[0099] A butterfly insert is a mixing organ with an open profile, which usually has at least three wings that have a high dispersing effect.

[0100] In a preferred method, the provision of the metal oxide dispersion in step (Al) is carried out by stirring the total amount of the at least one metal oxide (M) into water in at least two portions, wherein the portion stirred in first is stirred in at a higher stirring speed of the dissolver disk and a lower stirring speed of the butterfly insert compared to the portion stirred in subsequently.

[0101] The stirring process according to step (Al) according to the invention has the particular advantage that the metal oxide dispersion produced thereby has particularly good rheological properties, which is accompanied by easy handling.

[0102] It is preferred that the dispersing agent in step (Al) is water or an aqueous solution, preferably an aqueous solution with a pH value in the range of 1.0 to 7.0, preferably from 1.5 to 6.0, particularly preferably from 2.0 to 4.0.

[0103] The pH of the dispersant in step (Al ) can be adjusted by adding acid, preferably by adding phosphoric acid.

[0104] The at least one metal oxide in step (Al ) is preferably selected from a pyrogenic silicon dioxide or a precipitated silicon dioxide, in particular from a pyrogenic silicon dioxide.

[0105] The silicon dioxide provided in step (Al) is preferably in powder form. The powdered silicon dioxide preferably has aggregate sizes of 100 nm to 500 nm, measured by dynamic light scattering.

[0106] Mixing the metal oxide provided in step (Al) with the aqueous solution preferably produces a dispersion. At the end of the dispersion process, the dispersions can also be freed from non-dispersible, unwetted, and other coarse particles by sieving.

[0107] In a preferred method, the pH value is increased in step (A2 ) by 0.5-5.5 units, wherein preferably the target pH value after the change of the pH value in step (A2 ) is in the range of 4.0 to 8.0, particularly preferably in the range of 5.0 to 7.0.

[0108] The pH is raised in step (A2) preferably by adding suitable bases, in particular by adding a basic coagulant to the metal oxide dispersion from step (Al). Examples of the basic coagulant are alkali and alkaline earth metal hydroxides, carbonates and mixtures thereof, such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, magnesium carbonate, magnesium hydroxide carbonate, NH3 or mixtures thereof, in particular magnesium hydroxide carbonate.

[0109] In a preferred embodiment, during step (A2 ) the dispersion is first acidified to achieve a pH value < 4.0, and subsequently the reaction mixture is raised to a value > 4.0 with a base.

[0110] In the event that the pH value is raised exclusively during step (A2 ), an aqueous solution with pH < 4.0 can already be used in step (Al ) before the pH value is then raised to a value > 4.0 in step (A2 ).

[0111] The pH increase in step (A2) is preferably carried out by stirring and / or kneading. Planetary mixers or centrifugal mixers, for example, can be used for this purpose. The increase in pH in step (A2) is accompanied by an increase in viscosity, so that a highly viscous mass is typically obtained.

[0112] The production of shaped bodies by forming in step (A3) is preferably carried out by extrusion, tableting, or pressing, particularly by extrusion. All equipment known to those skilled in the art, such as extruders, tablet presses, or piston extrusion presses, is conceivable. The geometry of the shaped body results from the respective forming tool selected. Geometries such as rings, pellets, cylinders, wagon wheels, spheres, etc., can be produced. The length of rings and pellets is preferably defined directly after forming using a cutting device.

[0113] After shaping, the molded part is dried in process step (A4). This is preferably carried out using methods known to those skilled in the art (e.g., climate chamber, drying oven, IR heating, microwave). Preferably, the drying takes place in a climate chamber under controlled humidity. Drying can be carried out at temperatures preferably between 25°C and 200°C, more preferably between 30°C and 100°C, and most preferably between 40°C and 80°C. The drying time depends on the ratio of metal oxide to water, but is preferably between 2 and 48 hours. Process step (A4) can be carried out at atmospheric pressure at 1013 mbar or under reduced pressure. If the molded part is dried under reduced pressure in step (A4), the pressure can be reduced to 10 -3 mbar to normal pressure, in particular 10 -1 mbar to 800 mbar. After drying, sintering takes place according to methods known to those skilled in the art.

[0114] The sintering step (A4) is also called calcining and can take place at a temperature Ts in the range of 800°C to 1200°C, especially at 900°C to 1100°C.

[0115] Sintering is carried out particularly under gentle heating rates, for example 180 °C / h, and gentle cooling rates, for example 80 °C / h. These gentle heating and cooling rates ensure that the mechanical stability of the sorbents is not compromised, for example, due to the occurrence of mechanical stresses at excessively rapid heating and / or cooling rates.

[0116] Calcination in a furnace under an air atmosphere is preferred. An additional gas can be added to the air. Various protective gases are suitable for this purpose. All protective gases known to experts are suitable, with nitrogen, argon, or helium being particularly preferred. The air can also be completely replaced by the protective gas.

[0117] The sintering in step (A4) usually takes place for a period of 1-10 hours, preferably 4-8 hours.

[0118] Fine-pored molded bodies can be formed from finely divided silica by calcination. The proportion of pores with a diameter between 10 nm and 20 nm is typically more than 50%, preferably more than 70%, and particularly preferably more than 80%.

[0119] The at least one amine-based sorbent (ii) in the process according to the invention is preferably defined as described above and can be an organic amine-based sorbent.

[0120] The organic sorbent in the process according to the invention can be an organic monoamine or polyamine, wherein the polyamine comprises at least two N atoms per molecule, which are separated by at least one C atom, in particular selected from the group consisting of ethyleneamine, aminosilane, polyethyleneimine (PEI), polypropyleneamine, polyvinylpyridine, polydimethylaminoethyl methacrylate, polyamidoamine, polyvinylamine and polyallylamine.

[0121] The ethyleneamine in the process according to the invention can be selected from the group consisting of ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), aminoethylethanolamine (AEEA), aminoethylpiperazine (AEP), piperazine (PIP), hydroxyethylpiperazine (HEP), pentaethylenehexamine (PEHA) and polyethylenepolyamine (PEPA).

[0122] The aminosilane in the process according to the invention can be selected from the group consisting of aminopropylsilane, [3- (2- Aminoethylamino ) -propyl] -trialkoxysilane, 3- [2- (2-Aminoethylamino ) -ethylamino] -propyltrialkoxysilane, mixtures thereof and condensation products of 3-Aminopropyltrialkoxysilane.

[0123] The polyamine in the process according to the invention can be silylated, for example obtainable by reacting one or more amino groups of the polyamine with suitablely functionalized alkoxysilanes, for example selected from the group consisting of 3-chloropropyl-trialkoxysilane, 3-chloropropyl-trialkoxysilane, glycidoxypropyl-trialkoxysilane and isocyanatopropyl-trialkoxysilane.

[0124] The polyamine is obtainable in particular by silylation, which can be carried out in isolation or in situ.

[0125] The impregnation in step (B) is preferably carried out by bringing the molded body into contact with the at least one sorbent for CO2.

[0126] The impregnation is preferably carried out by mixing, spraying or soaking the molded body.

[0127] "Impregnation" within the meaning of this invention means the penetrating treatment with liquid, dissolved, emulsified, or dispersed impregnating agents. The impregnating agent can be physically deposited on the inner and outer surfaces of the porous molded body or bond to it chemically, either wholly or partially.

[0128] When the molded body is contacted with the at least one sorbent (ii), which may be in solution, during step (B), the resulting mixture can be stirred, for example by means of a magnetic stirrer or KPG stirrer.

[0129] In a particularly preferred method, impregnation in step (B) is carried out by bringing the molded body into contact with a volume of the pure sorbent (i.e., the sorbent in substance) Vs which corresponds at least to the desired proportion of the total pore volume based on a specific weight of the molded body. For a PVo of 1.5 cm³ 3 With a weight of 25.0 g for the molded part and a desired loading of 50%, Vs is therefore, for example, at least 0.5 x 37.5 cm. 3 = 18.75 cm 3 .

[0130] The calculation of the volumes Vs of the sorbent used for loading refers to volumes under standard reaction conditions, i.e. 25 °C and 1013 hPa.

[0131] According to the invention, the lower limit of the load is at least 40% of PVo and the upper limit of the load is at most 70% of PVo.

[0132] The loading of the molded body can be quantitative, meaning the entire volume Vs is used to functionalize the PVo. However, an excess of Vs may be necessary, as not all of the added volume Vs leads to the functionalization of the PVo. To achieve the desired loading values, it is therefore advantageous to use a slight excess of Vs. In this context, it is particularly advantageous to use an excess of Vs of 15 vol.%.

[0133] The lower limit of the loading according to the invention is achieved by molding the body with a volume V s functionalized, which corresponds to at least 40%, in particular at least 55% of PVo (based on a specific weight of the molded body).

[0134] The upper limit of the load according to the invention is reached by molding the body with a volume V sThe functionalized sorbent is at most 85%, and in particular at most 70%, of PVo (based on a specific weight of the molded body). Particularly preferably, the impregnation in step (B) is carried out by bringing the molded body into contact with a volume of the pure sorbent (i.e., the sorbent in substance) Vs, which corresponds to at least 40% and at most 85% of PVo, and in particular at least 55% and at most 85% of PVo (based on a specific weight of the molded body), whereby solvent may also be added. The total volume of added solvent and sorbent (in substance) may exceed PVo (based on a specific weight of the molded body).

[0135] Thus, the inventive loading of at least 40% and at most 70% of PVo can be achieved.

[0136] Vs can be calculated using the following equation ( III )

[0137] V s= x · PV0· m FK (III)

[0138] where x represents the desired proportion of the total pore volume and can take a value between 0.4 and 0.85, preferably between 0.55 and 0.85, PVo is as defined above, and HIFK represents the weight of the molded body in g and can take any value depending on the batch size.

[0139] The method according to the invention is therefore preferably scalable to any size.

[0140] When impregnating the molded body, it is irrelevant for achieving optimal adsorption capacities whether the sorbent is used in its pure form, i.e., as a substance, or dissolved in a solvent. However, if the sorbent is used only in its pure form, spontaneous and irregular coating is usually observed due to the viscosity of the amine-based sorbent. This can result in a deterioration of the CO₂ binding capacity. Depending on the choice of sorbent and solid, however, sufficient binding capacities can also be achieved without a solvent.

[0141] In a particularly preferred embodiment, the at least one sorbent (ii) is present dissolved in a solvent during the impregnation process in step (B). The total volume of added solvent and sorbent (in substance) may exceed PVo (based on a specific weight of the molded part).

[0142] In the event that the at least one sorbent (ii) is dissolved in a solvent, the total volume Vtotal of the mixture essentially corresponds to the sum of Vs and the volume of the added solvent VLM. For the partial loading according to the invention to be achieved, it is only crucial that the volume Vs, which corresponds to the volume of the sorbent in solution in substance, satisfies the limits according to the invention. The amount VLM can be chosen arbitrarily. ges PVo (based on a specific weight of the molded body) may be exceeded.

[0143] Preferably the mass ratio of solvent to solid is 40:1 - 1:1, more preferably 10:1 - 2:1.

[0144] The preferred embodiment, in which the at least one sorbent (ii) is dissolved in a solvent during impregnation in step (B), is also referred to as the Pseudo Incipient Wetness (PIW) method. In this method, the sorbent is typically dissolved or dispersed in a solution (e.g., aqueous or organic). This mixture can then be applied to the molded part, with the volume of the added mixture being V. ges The pore volume of the molded body PVo (based on a specific weight of the molded body) can be exceeded many times over, e.g. by approximately 3 to 10 times.

[0145] The crucial point here, as already explained, is that the added volume of the sorbent V s in the mixture corresponds to the limits according to the invention in order to achieve partial loading.

[0146] The term “pseudo” is based on the fact that the volume of adsorbent dissolved in the mixture refers to the pore volume of the support material, but not to the volume of the total mixture of solvent and adsorbent.

[0147] In contrast, with the Incipient Wetness Method (IWM), the total volume of adsorbent and solvent used refers to the pore volume of the molded body.

[0148] The "incipient wetness method" is known in the literature in connection with the coating of support materials with a catalyst, and its principles are described in Marceau, E.; Carrier, X.; Chet, M., Impregnation and Drying. In Synthesis of Solid Catalysts, 2009; pp. 59-82. Surprisingly, it has been shown that the incipient wetness method is also suitable for coating the molded bodies according to the invention with the CO2 sorbent in such a way that CO2 binding sites are homogeneously distributed over the entire surface of the molded body. This allows for particularly high sorption efficiencies in the sorbent to be achieved. In the incipient wetness method, the sorbent is typically dissolved or dispersed in a solution (e.g., aqueous or organic). This mixture can then be applied to the support material, which preferably has the same pore volume as the volume of the added mixture.Through capillary action, the mixture is drawn into the pores, leading to functionalization there.

[0149] The at least one sorbent (ii) may be in substance and liquid form or dissolved in a solvent during the impregnation process in step (B).

[0150] The solvent is preferably an organic solvent and more preferably has a boiling point of at most 200 °C, more preferably at at most 150 °C, in each case at 1013 mbar.

[0151] Examples of suitable solvents include water; alcohols such as methanol, ethanol, n-propanol, isopropanol, n-amyl alcohol, i-amyl alcohol; ethers such as dioxane, tetrahydrofuran, diethyl ether, diisopropyl ether, diethylene glycol dimethyl ether; chlorinated hydrocarbons such as dichloromethane, trichloromethane, tetrachloromethane, 1,2-dichloroethane, trichloroethylene; hydrocarbons such as pentane, n-hexane, hexane isomer mixtures, heptane, octane, white spirit, petroleum ether, benzene, toluene, xylenes; ketones such as acetone, methyl ethyl ketone, diisopropyl ketone, methyl isobutyl ketone (MIBK); esters such as ethyl acetate, butyl acetate, propyl propionate, ethyl butyrate, ethyl isobutyrate; carbon disulfide and nitrobenzene, or mixtures of these solvents.

[0152] The impregnation in step (B) is preferably carried out in a temperature range of 0-150 °C, more preferably in a temperature range of 15-120 °C. The impregnation in step (B) is preferably carried out at normal pressure, under increased pressure or under vacuum.

[0153] Normal atmospheric pressure is usually 1013 mbar.

[0154] In the event that impregnation in step (B) takes place under increased pressure, the maximum pressure can be 2 bar.

[0155] In the event that impregnation in step (B) takes place under pressure, the pressure can be 10 -3 mbar to normal pressure, in particular 10 -1 mbar to 500 mbar.

[0156] In a preferred method, the molded body is pre-impregnated at a pressure of 10 -3 up to 10 2 mbar treated; and / or dried.

[0157] The impregnation in step (B) of the provided molded body with at least one sorbent for CO2 in order to functionalize the molded body is preferably carried out together with at least one impregnation aid selected from wetting agent, emulsifier, dye, binder, adhesion promoter, higher alcohols and higher polyols.

[0158] In a preferred embodiment, the molded part retains its shape, defined by the molding tool / mold, at the moment of manufacture. Deformations during and immediately after molding cause density differences and stresses that lead to defects (flaking, fine dust) on the molded part during the drying and sintering process. According to the invention, the manufactured carriers exhibit a flaking content of preferably less than 5 wt.%, more preferably less than 1 wt.%, and most preferably less than 0.5 wt.%. Flaking is disadvantageous because it leads to a high pressure drop in a column or reactor in the application.

[0159] The present invention is therefore directed in particular to a sorbent for CO2 obtainable by the inventive method for producing a sorbent for CO2, wherein the impregnation is preferably carried out by means of the pseudo incipient wetness method described above.

[0160] Another aspect of the present invention is directed towards the use of the sorbent according to the invention for CO2 for the reversible binding of CO2 from a gas mixture, in particular in the form of a fixed bed sorbent, for example for CCU, CCS and / or DAC.

[0161] Reversible binding is achieved particularly through chemisorption. In this case, the CO2 is bound to the inner surface of the molded body by chemical bonding with the sorbent with which the metal oxide is functionalized. By increasing the temperature and / or decreasing the pressure, the chemisorbed CO2 can be released from the molded body and thus driven off. This has the advantage that the CO2 can not only be removed from the gas phase (e.g., DAC, CCS), but can also be released again at any later time and, for example, fed into a process that uses CO2 as a feedstock (e.g., CCU). Examples of implementation

[0162] Unless otherwise stated, the following examples were carried out at atmospheric pressure, i.e., at about 1013 mbar, and at room temperature, i.e., about 25°C or a temperature that occurs when the reactants come together at room temperature without additional heating or cooling, and describe the basic feasibility of the present invention, without, however, limiting it to the contents disclosed therein.

[0163] Determination of pore volume using mercury porosometry

[0164] The pore volumes are determined according to ISO 15901-1.

[0165] Determination of CO2 adsorption capacity

[0166] The BELCAT II gas adsorption analyzer from Microtrac is used to determine the CO2 adsorption capacity. Typically, the temperature-programmed desorption (TPD) method is employed, which works as follows.

[0167] For sample preparation, the substrate to be examined is heated to 100 °C under a continuous stream of helium and held at this temperature for 30 minutes.

[0168] The sample is then cooled to 40 °C at a cooling rate of 12 K / min. A second cooling step to 30 °C takes place at a cooling rate of 0.66 K / min, with both cooling steps performed under a continuous helium flow. For analysis, the sample is first rinsed with helium at 30 °C for 15 min. Then, CO₂ is passed over the sample at 30 °C for 10 min. If necessary, the CO₂ can be humidified using a commercially available vapor injection device (“Bubbier”). The sample is then treated in a helium stream at 30 °C for 20 min.

[0169] Helium is used as the desorption gas. The temperature of the support is increased to 150 °C at a rate of 5 K / min (linear temperature gradient) and the temperature is held for 15 minutes.

[0170] The gas mixture is passed through a dry molecular sieve (3 Å) to remove water and analyzed using a thermal conductivity detector (TCD) and mass spectrometry (MS). This allows the desorbed amount of CO2 to be determined.

[0171] Determination of the N or SiO2 content in the sorbent

[0172] The determination is carried out using standard analytical methods of elemental analysis.

[0173] Example 1:

[0174] General procedure for the production of amino-functionalized sorbent materials by impregnation of the carrier with an amine-based sorbent in methanolic solution

[0175] The substrate is impregnated in a three-necked flask equipped with a column head / distillation apparatus and a KPG stirrer with a crescent-shaped stirring blade. The silica molds are placed in the three-necked flask and are dried for 2 hours at room temperature under a vacuum of < 1.0 mbar before the sorbent is added. For functionalization, a solution of methanol and sorbent (solvent to mold mass ratio = 10:1) is added to the vacuum-sealed three-necked flask. Methanol is removed from the reaction solution under reflux at 50 °C for 1.5 hours while stirring. A high vacuum (pressure < 1.0 mbar) is then maintained for another hour. The functionalized adsorbent material is subsequently dried for two hours in a drying oven at 80 °C under a nitrogen atmosphere.

[0176] Example 2:

[0177] 59% load

[0178] Mass ratio of solvent to molded part = 10:1

[0179] 25.0 g of a silica-based molded body, characterized by a pore volume of 1.5 cm³ 3 / g, are functionalized according to Example 1 by impregnation with a methanolic solution of 22.5 g pentaethylenehexamine (available from Merck KGaA, Darmstadt, Germany) in 250 ml methanol (mass ratio solvent to molded body = 10:1). The volume of pentaethylenehexamine used in solution corresponds to 60 vol% of the pore volume of the silica-based molded body (loading 59%).

[0180] The determined occupancy rate of the molded body is 59 vol%, based on the pore volume determined experimentally by mercury porosometry. The nitrogen content is 11.8 mmol per gram of molded body (mean of three individual measurements). The adsorption capacity determined by chemisorption is 2.70 mmol CO₂ per gram of molded body (mean of three individual measurements).

[0181] Loading:

[0182] The sorbent loading of 59% in this example results from equation ( I ) and a measured PVo = 1.5 mL / g, a measured PVB = 0.39 mL / g and a factor w = 0.645 measured by elemental analysis.

[0183] Adsorption capacity:

[0184] Based on the experimentally determined nitrogen content of the impregnated solid, the mass or molar content of nitrogen on the solid can be deduced:

[0185] Nitrogen content: 11.75%

[0186] Equivalent to 0.118 g N / g sorbent.

[0187] With a molecular weight of nitrogen of 14 g / mol, this corresponds to a proportion of 8.39 mmol N / g sorbent.

[0188] AK C02 was determined to be 2.70 mmol / g sorbent.

[0189] According to equation ( II ), this results in an excellent AE of 64%.

[0190] Example 3:

[0191] Mass ratio of solvent to molded part = 5:1

[0192] The impregnation of a silica-based molded body, characterized by a pore volume of 1.5 cm³ 3 / g, are prepared according to the procedure in Example 1. The volume of pentaethylenehexamine used in solution corresponds to 60 vol% of the pore volume of the silica-based molded body. The measured CCt binding capacity is 2.826 mmol / g (mean of three individual values). The loading is 56%. Example 4:

[0193] Mass ratio of solvent to molded part = 2:1

[0194] The impregnation of a silica-based molded body, characterized by a pore volume of 1.5 cm³ 3 / g, is prepared according to the procedure in Example 1. For functionalization, a solution of methanol and sorbent is used (mass ratio of solvent to molded body = 1:2). The volume of pentaethylenehexamine used in the solution corresponds to 60 vol% of the pore volume of the silica-based molded body (loading 57%). The measured CO2 binding capacity is 2.895 mmol / g (mean of three individual values).

[0195] Example 5:

[0196] No solvent

[0197] The impregnation of a silica-based molded body, characterized by a pore volume of 1.5 cm³ 3 / g, is prepared according to the Incipient Wetness method. The difference to PIW in this example is that no solvent is used. In Example 5, the pure amine-containing sorbent, pentaethylenehexamine, is used instead of a solution.

[0198] The carrier is impregnated in a three-necked flask equipped with a column head / distillation apparatus and a KPG stirrer with a crescent-shaped stirring blade. The silica molds are placed in the three-necked flask and are dried for 2 hours at room temperature and under a vacuum of < 1.0 mbar before the sorbent is added. For functionalization, the sorbent, pentaethylenehexamine, is added to the vacuum-sealed three-necked flask while stirring. The volume of pentaethylenehexamine added corresponds to 60 vol% of the pore volume of the silica-based solids (loading 32%). A high vacuum (pressure < 1.0 mbar) is then maintained for another hour. The functionalized adsorbent material is subsequently dried for two hours in a drying oven at 80 °C under a nitrogen atmosphere. The measured CO₂ binding capacity is 1.748 mmol / g (mean of three individual measurements).

[0199] Example 6:

[0200] Binding capacity increases with increasing pore volume at the same partial loading.

[0201] Silica-based molded bodies with variable pore volume of 0.86 cm³ 3 / g (A), 1, 17 cm 3 / g (B) and 1.5 cm 3 The samples (C) show increasing CCt binding capacities with increasing pore volume at the same partial volume loading of the support material. At an occupancy of approximately 60% of the pore volume, the measured CO2 binding capacity increases with increasing pore volume from 1.46 mmol / g (A) to 2.17 mmol / g (B) to 2.70 mmol / g (C).

[0202] Example 7:

[0203] Pore ​​volume-dependent loading with identical pore volume of the support material

[0204] Three types of molded bodies are described below (initial pore volume PVo is 0.86, 1.17 and 1.5 cm³ respectively). 3 / g) loaded with increasing proportion of the total pore volume. The sorbent materials are prepared according to the procedure described in Example 1. Table 1: PVo = 0.86 cm³ 3 / G

[0205] Partial CO2 adsorption efficiency, loading with PEHA binding capacities / %

[0206] / Vol% / mmol / g

[0207] 850, 184

[0208] 62 1, 73 40

[0209] 60 1, 46 37

[0210] 58 1, 53 52

[0211] 40 1, 27 57

[0212]

[0213] Table 2: PVo = 1.17 cm 3 / G

[0214] Partial CO2 adsorption efficiency: Loading with PEHA binding capacities

[0215] / %

[0216] / Vol% / mmol / g

[0217] 890, 214

[0218] 820, 427

[0219] 62 2, 17 43

[0220] 51 2, 49 56

[0221] 43 2, 47 60

[0222]

[0223] Table 3: PVo = 1.5 cm 3 / G

[0224] Partial CO2 adsorption efficiency, loading with PEHA binding capacities / %

[0225] / Vol% / mmol / g

[0226] 91 0, 16 2

[0227] 760, 9615

[0228] 70 2, 40 47

[0229] 68 2, 58 52

[0230] 59 2, 70 64

[0231] 48 2, 79 61

[0232]

[0233] The present invention is further characterized by the following points:

[0234] 1. Comprehensive CO2 sorbent

[0235] (i) a shaped body (i) made of at least one metal oxide;

[0236] and

[0237] (ii) at least one amine-based sorbent (ii) for CO2 with which the molded body (i) is partially loaded,

[0238] wherein the molded body has a porous structure with a total pore volume PVo,

[0239] wherein the partial loading of the molded body (i) with the at least one sorbent (ii) is characterized in that 40-70% of PVo are loaded with the sorbent.

[0240] 2. Sorbens according to point 1, the loading being determined according to the following equation ( I ):

[0241] / PVB \

[0242] Load = I 1 - — ) ■ 100% (I)

[0243] \ P o 1

[0244] where PV B the pore volume measured after loading in mL / g, PV0 the total pore volume of the initial molded body in mL / g, and ) the dimensionless mass fraction of SiO2 in the total mass of the sorbent.

[0245] 3. Sorbent according to point 1 or 2, wherein the desired loading of the molded body in % of PVo is achieved by coating the molded body with a volume of the pure sorbent V sfunctionalized (for example, using pseudo-IWM), which corresponds at least to the desired proportion of the total pore volume (based on a specific weight of the molded body).

[0246] Sorbens according to one of the preceding points, wherein the loading of at least 40% and at most 70% of PVo is achieved by molding the body with a volume V s functionalized, which corresponds to at least 40% and at most 85% of PVo, in particular at least 55% and at most 85% of PVo (based on a specific weight of the molded body).

[0247] Sorbens according to one of the preceding points, which has an adsorption efficiency AE of at least 35%, where the AE is defined according to the following equation (II ):

[0248] ^ = ^£22. 2 - 100 % ( II )

[0249] Y

[0250] where AK COThe adsorption capacity of the sorbent for COo in mmol / g and y represents the proportion of nitrogen to the total mass of the sorbent in mmol / g.

[0251] Sorbens according to any of the preceding points, wherein the at least one metal oxide is selected from aluminium oxide, silicon dioxide (also known as silica), titanium dioxide or zirconium dioxide, preferably from silicon dioxide, in particular from amorphous silicon dioxide.

[0252] Sorbens according to one of the preceding points, wherein the metal oxide of the molded body has a mesoporous structure, in particular a mesoporous structure with an irregular pore structure.

[0253] Sorbens according to one of the preceding points, wherein the shaped body is built up from agglomerates of amorphous silicon dioxide.

[0254] Sorbens according to any of the preceding points, wherein the at least one metal oxide is selected from pyrogenic or precipitated silicon dioxide, in particular from pyrogenic silicon dioxide.

[0255] Sorbens according to one of the preceding points, wherein the molded body has dimensions in at least one dimension in the range of 0.5 mm to 30 mm, preferably 1.0 mm to 15 mm.

[0256] Sorbens according to one of the preceding points, wherein the molded body is sintered at a sintering temperature Ts.

[0257] Sorbens according to one of the preceding points, which has a compressive strength of at least 2 N / mm² 2 , preferably at least 8 N / mm 2 , exhibits.

[0258] Sorbens according to one of the preceding points, wherein the BET surface of the sorbs is in the range of 30 to 500 m 2 / g lies, especially in the range of 50 to 400 m 2 / G.

[0259] A sorbent according to any of the preceding points, wherein the at least one sorbent (ii) is capable of undergoing a reversible reaction with CO2, in particular a reversible sorption reaction. A sorbent according to any of the preceding points, wherein the at least one sorbent (ii) is an organic sorbent based on amines.

[0260] Sorben according to point 15, wherein the organic sorbent (ii) is amine-based and is an organic monoamine or polyamine, the polyamine comprising at least two N atoms per molecule separated by at least one C atom, in particular selected from the group consisting of ethyleneamine, aminosilane, polyethyleneimine (PEI), polypropyleneamine, polyvinylpyridine, polydime thylaminoethyl methacrylate, polyamidoamine, polyvinylamine and polyallylamine.

[0261] Sorbens according to point 16, wherein the ethyleneamine is selected from the group consisting of ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetraamine (TETA), tetraethylenepentamine (TEPA), aminoethylethanolamine (AEEA), aminoethylpiperazine (AEP), piperazine (PIP), hydroxyethylpiperazine (HEP), pentaethylenehexamine (PEHA) and polyethylenepolyamine (PEPA).

[0262] Sorbens according to point 16, wherein the aminosilane is selected from the group consisting of aminopropylsilane, [3- (2-Aminoethylamino ) -propyl] -trialkoxysilane, 3- [2- (2- Aminoethylamino ) -ethylamino] -propyltrialkoxysilane, mixtures thereof and condensation products of 3-Aminopropyltrialkoxysilane.

[0263] Sorbens according to one of points 16-18, wherein the polyamine is silylated, for example obtainable by reacting one or more amino groups of the polyamine with suitably functionalized alkoxysilanes, for example selected from the group consisting of 3-chloropropyl-trialkoxysilane, 3-chloropropyl-trialkoxysilane, glycidoxypropyl-trialkoxysilane and isocyanatopropyl-trialkoxysilane.

[0264] Sorbens according to point 19, wherein the silylated polyamine is obtainable by silylation, which is carried out either in isolation or in situ.

[0265] Sorbs according to one of the preceding points, furthermore comprehensive

[0266] (iii) at least one auxiliary substance (iii) selected from the group consisting of polymeric binders, silicon-containing binders such as silicates and silica sol, spreading agents and wetting agents.

[0267] Sorbens according to one of points 16-21, wherein the polyamine is present in combination with at least one amino-functional alkoxysilane.

[0268] Sorbens according to point 22, wherein the at least one amino-functional alkoxysilane is selected from the group consisting of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane and 3-aminopropyltriisopropoxysilane.

[0269] Sorbens according to one of the preceding points, wherein the sintering temperature Ts is in a range of 800-1200 °C, in particular in a range of 900-1100 °C.

[0270] Sorben according to one of the preceding points, which has a proportion of flaking of less than 5 wt.%, preferably less than 1 wt.% and most preferably less than 0.5 wt.% based on the total weight of the sorbent.

[0271] Method for producing a sorbent for CO2 according to one of points 1-25, comprising the following steps in the specified order:

[0272] (A) Providing a shaped body (i) made of at least one metal oxide (M); and

[0273] (B) Impregnating the provided molded body with at least one amine-based sorbent (ii) for CO2 in order to partially load the molded body with it.

[0274] Procedure according to point 26, wherein the provision of the molded body (i) in step (A) is carried out by the following steps in the specified order:

[0275] (Al ) Providing a metal oxide dispersion by dispersing at least one metal oxide (M) in a dispersing agent;

[0276] (A2) Coagulation of the dispersion by raising the pH value;

[0277] (A3) Shaping the coagulated dispersion to produce a green body; and

[0278] (A4) Drying and subsequent sintering of the green body at a sintering temperature T s , in order to produce the sintered molded body.

[0279] The method according to point 27, wherein the proportion of the at least one metal oxide in the metal oxide dispersion of step (Al) is 10-50 wt.%, based on the total mass of the metal oxide dispersion. The method according to one of points 27-28, wherein the provision of the metal oxide dispersion in step (Al) is carried out by stirring in the at least one metal oxide using a dissolver disc and a butterfly insert simultaneously.

[0280] Method according to point 29, wherein the provision of the metal oxide dispersion in step (Al ) is carried out by stirring the total amount of the at least one metal oxide (M) into water in at least two portions, wherein the portion stirred in first is stirred in at a higher stirring speed of the dissolver disc and a lower stirring speed of the butterfly insert compared to the portion stirred in after.

[0281] Method according to one of points 27-30, wherein the dispersing agent in step (Al) is water or an aqueous solution, preferably an aqueous solution with a pH value in the range of 1.0 to 7.0, preferably from 1.5 to 6.0, particularly preferably from 2.0 to 4.0

[0282] Method according to one of points 27-31, wherein the pH of the dispersant is adjusted in step (Al ) by adding acid.

[0283] Method according to one of points 27-32, wherein the pH of the dispersant is adjusted in step (Al ) by adding phosphoric acid.

[0284] Method according to one of points 27-33, wherein the at least one metal oxide in step (Al ) is selected from a pyrogenic silicon dioxide or a precipitated silicon dioxide, in particular from a pyrogenic silicon dioxide.

[0285] Method according to one of points 27-34, wherein the pH is increased in step (A2) by 0.5-5.5 units, wherein preferably the target pH after the increase in step (A2) is in the range of 4.0 to 8.0, particularly preferably in the range of 5.0 to 7.0.

[0286] Method according to one of points 27-35, wherein the increase of the pH value in step (A2 ) is carried out by adding a basic coagulant to the metal oxide dispersion, preferably by adding magnesium hydroxycarbonate.

[0287] Method according to one of points 27-36, wherein the shaping in step (A3) is carried out by extrusion.

[0288] Method according to one of points 27-37, wherein the drying in step (A4) takes place at a temperature in the range of 25°C and 200°C, preferably between 30°C and 100°C, most preferably between 40°C and 80°C.

[0289] Method according to one of points 27-38, wherein the sintering in step (A4 ) at a temperature T s in the range of 800-1200 °C, preferably 900-1100 °C.

[0290] Method according to one of points 27-39, wherein the sintering in step (A4) takes place at a heating rate of 100-250 °C / h, preferably 150-200 °C / h.

[0291] A method according to any one of points 27-40, wherein the sintering in step (A4) takes place for a period of 1-10 hours, preferably 4-8 hours. A method according to any one of points 26-41, wherein the at least one amine-based sorbent is an organic amine-based sorbent.

[0292] Method according to point 42, wherein the organic sorbent based on amines is an organic monoamine or polyamine, wherein the polyamine comprises at least two N atoms per molecule separated by at least one C atom, in particular selected from the group consisting of ethyleneamine, aminosilane, polyethyleneimine (PEI), polypropyleneamine, polyvinylpyridine, polydimethylaminoethyl methacrylate, polyamidoamine, polyvinylamine and polyallylamine.

[0293] Method according to point 43, wherein the ethyleneamine is selected from the group consisting of ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), aminoethylethanolamine (AEEA), aminoethylpiperazine (AEP), piperazine (PIP), hydroxyethylpiperazine (HEP), pentaethylenehexamine (PEHA) and polyethylenepolyamine (PEPA).

[0294] Method according to point 43, wherein the aminosilane is selected from the group consisting of aminopropylsilane, [3- (2-Aminoethylamino ) -propyl] -trialkoxysilane, 3- [2- (2- Aminoethylamino ) -ethylamino] -propyltrialkoxysilane, mixtures thereof and condensation products of 3-Aminopropyltrialkoxysilane.

[0295] Method according to any of points 43-45, wherein the polyamine is silylated, for example obtainable by reacting one or more amino groups of the polyamine with suitably functionalized alkoxysilanes, for example selected from the group consisting of 3-chloropropyl-trialkoxysilane, 3-chloropropyl-trialkoxysilane, glycidoxypropyl-trialkoxysilane and isocyanatopropyl-trialkoxysilane.

[0296] Method according to point 46, wherein the polyamine is obtainable by silylation, which can be carried out in isolation or in situ.

[0297] Method according to one of points 26-47, wherein the impregnation in step (B) is carried out by bringing the molded body into contact with a volume of the pure sorbent (i.e. the sorbent in substance) Vs which corresponds at least to the desired proportion of the total pore volume (based on a certain weight of the molded body).

[0298] Method according to one of points 26-48, wherein the impregnation in step (B) is carried out by bringing the molded body into contact with a volume of the pure sorbent (i.e. the sorbent in substance) Vs which corresponds to at least 40% and at most 85% of PVo, in particular at least 55% and at most 85% of PVo (based on a given weight of the molded body).

[0299] Method according to one of points 26-49, wherein the at least one sorbent (ii) is in substance and liquid form or dissolved in a solvent during impregnation in step (B).

[0300] Method according to one of points 26-50, wherein the impregnation in step (B) takes place in a temperature range of 0-150 °C, preferably in a temperature range of 15-120 °C.

[0301] Method according to one of points 26-51, wherein the impregnation in step (B) takes place at normal pressure, under increased pressure or under vacuum.

[0302] Method according to one of points 26-52, wherein the impregnation is carried out by mixing, spraying or soaking the molded body.

[0303] Method according to one of points 26-53, wherein the molded body is before impregnation

[0304] - at a suppression of 10 -3 up to 10 2 is treated in mbar; and / or

[0305] - is dried.

[0306] Method according to one of points 26-54, wherein in step (B) the provided molded body is impregnated with at least one sorbent (ii) for CO2 to functionalize the molded body, together with at least one impregnation aid selected from wetting agent, emulsifier, dye, binder, adhesion promoter, higher alcohols and higher polyols.

[0307] Use of the CO2 sorbent according to one of points 1-25 for the reversible binding of CO2 from a gas mixture, particularly in the form of a fixed-bed sorbent, for example for CCU, CCS and / or DAC. Note:

[0308] The invention underlying this patent application arose from a project funded by the Federal Ministry of Education and Research under grant number 03SF0705H. The applicant is responsible for the content of this patent application.

Claims

Claims 1. Comprehensive CO2 sorbent (i) a shaped body (i) made of at least one metal oxide; and (ii) at least one amine-based sorbent (ii) for CO2 with which the molded body (i) is partially loaded, wherein the molded body has a porous structure with a total pore volume PVo, wherein the partial loading of the molded body (i) with the at least one sorbent (ii) is characterized in that 40-70% of PV₀ are loaded with the sorbent.

2. Sorbens according to claim 1, wherein the loading is determined according to the following equation ( I ): / PVB \ Load = I 1 - — ) ■ 100% (I) \ P o 1 where PV B the pore volume measured after loading in mL / g, PV0 the total pore volume of the initial molded body in mL / g, and ) the dimensionless mass fraction of SiO2 in the total mass of the sorbent.

3. Sorbent according to claim 1 or 2, wherein the desired loading of the molded body in % of PVo is achieved by coating the molded body with a volume of the pure sorbent. V s is functionalized, which corresponds at least to the desired proportion of the total pore volume (based on a specific weight of the molded body).

4. Sorbens according to any of the preceding claims, wherein the loading of at least 40% and at most 70% of PVo is achieved by molding the body with a volume V s functionalized, which corresponds to at least 40% and at most 85% of PVo (based on a specific weight of the molded body).

5. Sorben according to any of the preceding claims, which has an adsorption efficiency AE of at least 35%, wherein the AE is defined according to the following equation (II ): AE = AK / γ · 2 · 100 % (II) Y where AK CO The adsorption capacity of the sorbent for CO2 in mmol / g and y represents the proportion of nitrogen to the total mass of the sorbent in mmol / g.

6. Sorbens according to one of the preceding claims, wherein the mold body is sintered at a sintering temperature Ts.

7. Sorbens according to any of the preceding claims, wherein the at least one metal oxide is selected from aluminium oxide, silicon dioxide, titanium dioxide or zirconium dioxide.

8. Sorben according to any one of the preceding claims, wherein the organic sorbent (ii) is amine-based and is an organic monoamine or polyamine, wherein the polyamine comprises at least two N atoms per molecule, which are connected by at least one carbon atom is separated, in particular selected from the group consisting of ethyleneamine, aminosilane, polyethyleneimine (PEI), polypropylenamine, polyvinylpyridine, polydimethylaminoethyl methacrylate, polyamidoamine, polyvinylamine and polyallylamine.

9. Sorbens according to any of the preceding claims, further comprising (iii) at least one auxiliary material selected from the group consisting of polymeric binders, silicon-containing binders such as silicates and silica sol, spreading agents and wetting agents.

10. A method for producing a sorbent for CO2 according to any one of claims 1-9, comprising the following steps in the specified order: (A) Providing a shaped body (i) made of at least one metal oxide (M); and (B) Impregnating the provided molded body with at least one amine-based sorbent (ii) for CO2 in order to partially load the molded body with it.

11. Method according to claim 10, wherein the provision of the molded body (i) in step (A) is carried out by the following steps in the specified order: (Al ) Providing a metal oxide dispersion by dispersing at least one metal oxide (M) in a dispersing agent; (A2) Coagulation of the dispersion by raising the pH value; (A3) Shaping the coagulated dispersion to produce a green body; and (A4) Drying and subsequent sintering of the green body at a sintering temperature T s , in order to produce the sintered molded body.

12. Method according to one of claims 10-11, wherein the impregnation in step (B) is carried out by bringing the molded body into contact with a volume of the pure sorbent Vs which corresponds at least to the desired proportion of the total pore volume (based on a specific weight of the molded body).

13. Method according to one of claims 10-12, wherein the impregnation in step (B) is carried out by bringing the molded body into contact with a volume of the pure sorbent Vs which corresponds to at least 40% and at most 85% of PVo (based on a specific weight of the molded body).

14. Method according to any of points 10-13, wherein the at least one sorbent (ii) is in substance and liquid form or dissolved in a solvent during the impregnation in step (B).

15. Use of the sorbent for CO2 according to one of claims 1-9 for the reversible binding of CO2 from a gas mixture.

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