NL2037550B1

NL2037550B1 - Direct air capturing method and direct air capturing device

Info

Publication number: NL2037550B1
Application number: NL2037550A
Authority: NL
Inventors: Sinha Mrigank; Roderick Blaazer Antoni; Van Kranendonk Jan
Original assignee: Zef B V
Priority date: 2024-04-26
Filing date: 2024-04-26
Publication date: 2025-11-11
Also published as: WO2025224134A1

Abstract

A continuous direct air capturing method of absorbing carbon dioxide and water from ambient air comprises contacting a flow of ambient air with liquid absorbent droplets flowing by gravity over wires. Loaded droplets are collected and then subjected to desorption for regeneration thereof. Regenerated liquid absorbent is recycled for further absorption. Captured carbon dioxide and water may be separated and stored for further processing. A device for continuous direct air capturing is also described. Fig.

Description

P36690NLO0/JV

DIRECT AIR CAPTURING METHOD AND DIRECT AIR CAPTURING DEVICE

Technical Field

The present invention relates to a method of capturing carbon dioxide and water from ambient air, also known as direct air capture (also known as DAC), and a direct air capturing device.

Technical Background

Direct air capture systems extract carbon dioxide directly from the atmosphere at any location. The captured carbon dioxide can be permanently stored underground in deep geological formations (CCS: carbon dioxide capture and storage) or used for a variety of applications (CCUS: carbon dioxide capture, utilisation and storage).

Direct air capture essentially differs from processes for the removal of carbon dioxide from process gas flows and flue gasses in industry. The concentration of carbon dioxide in ambient air (at present about 410 ppm) is much lower than the CO, amounts in typical process gases.

Significantly, the industrial process conditions, such as temperature and particularly pressure, but also flow rates, are much higher than ambient conditions. Furthermore in industry the process conditions including composition of gas flow to be treated are generally carefully controlled, while ambient conditions such as temperature and humidity of the ambient air typically vary throughout time. Therefore, DAC has developed its own technologies.

In the field of CO: capturing from ambient air several differing approaches are known.

Typically these can be distinguished by the capturing mechanism and capturing medium.

Another distinction between the several differing approaches is related to whether the process is performed batchwise or continuously.

Adsorption using metal organics, (size) separation using membranes, biological systems using (micro)algae and cyanobacteria are also known. Suitable membranes are expensive, and the lifetime of the membranes is comparatively low. A drawback of the biological systems is the low yield thereof and the incorporation of invasive species which may threaten domestic species.

Direct air capture using solid amines on porous supports or so called metal organic frameworks is a batchwise operated process. See e.g. WO2010/091831A1. Batchwise operated processes comprising repeated cycles of adsorption of carbon dioxide and subsequent desorption thereof and regeneration of the supported solid amines are slow processes and involve complex equipment. This type of batchwise processes are typically performed in a single adsorption/desorption reactor, wherein after capturing carbon dioxide the loaded adsorbent in the same reactor is subjected to a high temperature and/or reduced pressure to desorb the captured carbon dioxide. A disadvantage of such a batch process is that the same chamber and its content as a whole including adsorbent and support repeatedly need to be heated for desorption and cooled for adsorption, which is relatively inefficient in view of energy consumption. Another drawback thereof is the complexity of the chamber that needs large vacuum doors or ports to allow the voluminous air flow through the chamber and strong sealing in order to generate the vacuum.

Another approach is absorption of carbon dioxide from ambient air in a liquid absorbent using a so called moisture swing to recover the captured carbon dioxide from the liquid absorbent.

Typically, DAC including moisture swing is also a batchwise process, wherein water is evaporated from the solid sorbent in regenerating the liquid absorbent. In dry and sunny regions this is undesirable as it is considered a waste of valuable water. Moreover the carbon dioxide recovered from the absorbent is moist.

Continuous direct air capture using hydroxides as absorbent for absorption of carbon dioxide is also known.

US2009/0320688A1 has disclosed methods and apparatuses for extracting carbon dioxide from open air without heating or cooling the air. In an embodiment thereof a laminar airflow is allowed to contact a flow of solvent (the absorbent) on upstanding plates in a scrubber apparatus in a crossflow configuration. As a solvent capable of absorbing carbon dioxide a strongly alkaline solution is mentioned, such as aqueous sodium or potassium hydroxide solutions, which convert the captured carbon dioxide into carbonates. Organic sorbents like amines such as monoethanolamine (MEA) and dibutylamine (DBA) are considered viable possibilities. The collected fluid or CO: loaded solvent may be passed on directly to a recovery unit or recycled back to the top of the scrubber apparatus for additional collection of carbon dioxide.

A drawback of the use of hydroxides is that for regeneration of the reacted hydroxides high temperatures, typically over 500 °C are required. Liquid amines like MEA and DBA are susceptible to degradation, in particular at the elevated temperatures used for desorption in regenerating the absorbent and are volatile resulting in loss of absorbent from the system due to evaporation in the large flows of ambient air. Moreover, these amines are corrosive agents, raising the demands for the construction materials of the equipment.

Another drawback is that the mass transfer of carbon dioxide to the flowing solvent per area unit of the support {per volume unit) leaves something to be desired.

US6582498B1 has disclosed a method of scrubbing carbon dioxide and other gases from a gas mixture, such as from flue gas at power plants. The method includes flowing a liquid solvent such as tertiary amines or hindered secondary amines e.g. methyldiethanclamine {MDEA), 2-(dimethylamino)-ethanol (DEAE), 2-amino-2-methyt1-propanol (AMP) and 2-

amino-2-methyi-1, 3-propanediol, 2-{2-hydroxysthyl}- piperidine (HEP), down a wire so that the solvent forms drops which flow down the wire. These tertiary amines or hindered secondary amines are preferred over fast-reacting amines, like primary amines, because the latter form viscous liquids when loaded with carbon dioxide and require high temperatures and thus high energy consumption for regeneration, and are easily degraded, in particular caused by the repeated exposure to the high temperatures. Alternative solvents disclosed in this patent include inter alia reactive aqueous mixtures of carbonates, strong bases like alkali metal hydroxides and aqueous ammonia. The solvent may be used in a mixture with water. The formation and motion of drops on the wire is caused by fluid instability of the solvent, which contributes to the mixing the content of the droplets such that liquid elements at the surface of a droplet flow into the interior of the droplet. The gas mixture is flowed into contact with the solvent on the wire so that the solvent absorbs the non-aqueous component from the gas mixture. The fluid instability of the solvent increases the mass transfer rate of the absorption process.

An object of the present invention is to provide a continuous direct air capturing method and system that do not have the above drawbacks or at least to a lesser extent, or to provide a suitable alternative.

In particular the invention aims at providing a continuous method of capturing carbon dioxide and water from ambient air having a high absorption efficiency (high mass transfer rate) at reduced losses of absorbent using a liquid absorbent, that is less susceptible to (thermal/oxidative) degradation.

Summary of the invention

The present invention is directed to an absorption process using a liquid absorbent, in particular to an absorption based CO: and water capturing process using temperature/pressure swing based absorption/desorption steps.

According to the invention the method of capturing carbon dioxide and water at ambient conditions from ambient air comprises the steps of: a) in an absorption chamber flowing liquid absorbent droplets down a plurality of wires by gravity; b) flowing ambient air through the absorption chamber in contact with the liquid absorbent droplets on the plurality of wires for capturing carbon dioxide and water from the ambient air, thereby obtaining liquid absorbent droplets loaded with carbon dioxide and water;

C) collecting the liquid absorbent droplets loaded with carbon dioxide and water; dd) passing a flow of loaded liquid absorbent obtained in step c) to a desorption section; e) in the desorption section desorbing carbon dioxide and water from the flow of the loaded liquid absorbent, at elevated temperature and/or reduced partial pressure of carbon dioxide compared to ambient temperature and pressure conditions of step b), thereby obtaining a flow of desorbed liquid absorbent and carbon dioxide and water; f) collecting the carbon dioxide obtained in step Cc}; a) recycling the flow of desorbed liquid absorbent, derived from the desorption section, to step a); wherein the liquid absorbent is an etheramine comprising at least one amine group and at least one ether group or a solution thereof in a non-aqueous solvent, wherein the liquid absorbent has 2.8 moles or more of non-tertiary amines per kilogram unloaded absorbent, wherein the liquid absorbent is hygroscopic in ambient air, and wherein the unloaded liquid absorbent has a vapor pressure of 0.1 Pa or less at 20 °C.

The invention also relates to a direct air capturing device for recovering carbon dioxide and water from ambient air, preferably for use in the method according to the invention, wherein the device comprises an absorption chamber for contacting a flow of ambient air, wherein the absorption chamber is defined by a housing having an intake for ambient air and an outlet for at least partially carbon dioxide depleted air, wherein a plurality of wires are arranged in the absorption configured for guiding liquid absorbent droplets by gravity, wherein the ambient air passes along a flow path from the intake to the outlet in contact with the liquid absorbent droplets on the plurality of wires, a distributor for forming droplets of the liquid absorbent at each of the plurality of wires, a collector for collecting carbon dioxide and water loaded liquid absorbent droplets at the bottom of the wires, a desorption section having a feed for the loaded liquid absorbent and an outlet for desorbed liquid absorbent and an outlet for collecting carbon dioxide, the desorption section being provided with heating means and/or partial pressure reducing means, wherein the collector is in fluid connection with the desorption section and wherein the outlet for desorbed fluid absorbent of the desorption section is in fluid connection with the absorption chamber, preferably wherein the distributor comprises a bottom plate having through holes and droplet forming nozzles for each wire, through which the respective wire extends, said droplet forming nozzle comprising a restriction part configured for introducing a pressure drop to homogenize the liquid absorbent flow between wires, a nozzle at the lower face of the bottom plate with a pocket part having a cross-section larger than the restriction part at the nozzle base and a nozzle tip, wherein the nozzle has an at least partly open lateral side, and the open sides of neighbouring nozzle do not face one another.

The direct air capturing method according to the invention aims at optimizing the rate of carbon dioxide and water uptake from the ambient air by the hygroscopic etheramine instead of scrubbing a gas mixture clean from carbon dioxide at maximum CO; reduction. In the invention ambient air having a low carbon dioxide concentration and variable moisture content is the source of carbon dioxide and water to be captured therefrom contrary to the gas mixtures such as flue gas disclosed in US6582498B1. Furthermore an etheramine for binding carbon dioxide is used in the invention, which on the average is hygroscopic under the prevailing conditions, and thus capable of capturing water in addition to carbon dioxide, while the absorbents used in cleaning industrial process flows, such as those disclosed in

US6582498B1, are typically aqueous mixtures of amines, and thus susceptible to loss of water. If the method of US6582498B1 were to be used for capturing carbon dioxide from ambient air, due to the large volume of ambient air to be passed over the wires, water loss would be so serious that make-up water should be added regularly in order to maintain the drop formation properties and viscosity within the operating range. In the invention the products aimed for are carbon dioxide and water, while in US6582498B1 a CO: scrubbed gas mixture is the intended product, wherein the carbon dioxide is removed for disposal.

The method according to the invention is a continuous process, wherein the absorption step and desorption step are carried out on a continuous flow of absorbent at the same time, contrary to a batchwise process. The supporting wires are not involved in the absorbent regeneration steps, such as is the case in processes involving absorbents impregnated on porous supports.

Brief description of the drawings

The invention is illustrated in the attached drawings, wherein:

Fig. 1 shows diagrammatically an embodiment of a device for performing the method according to the invention;

Fig. 2 shows an embodiment of a series of droplets on a wire;

Fig. 3A shows an embodiment of a drop forming nozzle of a distributor in a direct air capturing device according to the invention;

Fig. 3B is a bottom view of the embodiment shown in Fig. 3A;

Fig. 4 shows an embodiment of a process diagram for conversion of carbon dioxide from air into methanol;

Fig. 5 shows diagrammatically another embodiment of a device for performing the method according to the invention;

Fig. 6 is a graph showing the evaporation of absorbent as a function of vapor pressure;

Fig. 7 is a diagram showing the vapor pressure of several absorbents at various temperatures;

Fig 8 is a diagram showing the viscosity of various carbon dioxide loaded absorbents at 30 °C and 50 % RH;

Fig. 9 is a diagram of the thermal decay of various absorbents at 120 °C; and

Fig. 10 is a graph showing the carbon dioxide capture rate as a function of time for various absorbents.

In the Figs. identical or similar parts are indicated by the same reference numeral.

Detailed description of the invention

Absorption by droplets on wire

In the first steps a) and b) of the continuous method of capturing carbon dioxide and water according to the invention a flow of atmospheric ambient air, today typically having a CO: concentration of about 410 ppm, is allowed to contact a flow of liquid absorbent droplets at the prevailing ambient conditions. E.g. in geographical areas having sufficient light incidence the apparatus used may achieve a temperature of 50 °C or more. Then the ambient air flow, provided it has a (slightly) lower temperature, may actually cool the absorption chamber. The liquid absorbent droplets flow along a plurality of wires by gravity. Typically, the wires are vertically arranged. The generation of the individual droplets and the movement thereof along a wire is the result of fluid instability of the liquid absorbent. When the absorbent absorbs CO: and HzO the viscosity rises sharply, forming a stagnant surface layer of the droplet, which ‘saturated’ stagnant layer would inhibit diffusion of fresh CO: and H,O from ambient air through the absorbent. However, as a result of the fluid instability the content of a droplet is continuously mixed so that formation of such a stagnant surface layer of the droplet loaded with carbon dioxide and water due to increased viscosity thereof, is prevented. Mixing of the absorbent droplet on the wire will increase mass transfer and diffusion rate, thereby positively effecting the absorption rate. Because of the large volume of ambient air that flows through the absorption chamber, the pressure drop should be low in order to avoid the necessity of large and powerful fans and thus high energy consumption. At the same time the surface area for mass transfer should be high in order to achieve a high absorption capacity. The wires are typically vertically arranged in a densely spaced wire grid, preferably as close to one another as possible without the risk of droplets running down on neighbouring wires to contact one another thereby preventing recombination of these droplets. A grid having a regular triangular spacing, e.g. in the order of several mm, is an example of a densely spaced grid. Other patterns such as square or parallelogram like diamond are also contemplated. The wire arrangement provides low pressure drops while maintaining a competitive (relative) surface area (m2/m3) for mass transfer compared to packed columns. The ambient air flow and liquid absorbent droplets flow may be in a crossflow or a counterflow configuration. A co- flow configuration is also feasible

The wire material is inert to the respective etheramine or non-aqueous solution thereof.

Advantageously the wires can be made by extrusion. Examples comprise polypropylene, polyamide and polyphenylene sulphide. If necessary, in view of wetting, a wetting coating may be present on the wire surfaces.

In an embodiment the absorption chamber may comprise in total up to several tens of kilometres of wire, e.g. about 30 km, at a length of an individual wire in the range up to a few metres, such as 2 metres. In order to reduce the number of attachment points, a piece of wire having a length of a large number of individual wires e.g. 200 or more, is advantageously wound multiple times from an upper header module in the distributor of the absorption chamber and a lower header module in the collector, of which the only two ends are fixed such as knotted to the headers. A number of these header modules can be arranged in a stack to provide a densely spaced wire grid.

Given a droplet flow path on a wire having a length in the range of 0.1 - 5m, suchas 0.1-2.5 m, typically in step a) the flow rate of the liquid absorbent over the film supporting surface is in the range up to several cm/s. Then in step a) the corresponding contact time of the liquid absorbent for carbon dioxide and water from the ambient air in a single pass over a wire in the absorption chamber is in the range of 1 second to 1 hour.

In order to distribute the liquid absorbent over the individual wires advantageously a distributor is provided.

Etheramine liquid absorbent

According to the invention the liquid absorbent is an etheramine comprising at least one amine group and at least one ether group or a solution thereof in a non-aqueous solvent, wherein the liquid absorbent has 2.8 moles or more of non-tertiary amines per kilogram unloaded absorbent, wherein the liquid absorbent is hygroscopic in ambient air, and wherein the unloaded liquid absorbent has a vapor pressure of 0.1 Pa or less at 20 °C.

The liquid absorbent used in the method according to the invention comprises an etheramine, which comprises at least one amine (-NHz) group and at least one ether (-C-O-C-) group, preferably an aliphatic etheramine, more preferably an aliphatic etheramine having at least one amine group. Amine groups may be sterically hindered. In the invention the amine groups are predominantly not sterically hindered, although some steric hinderance might be feasible, for example when the absorbent also comprises an non-aqueous solvent such as PEG. Therefore the amine groups in the etheramine used in the invention, are non- tertiary amines, preferably primary amines. The (poly)ether moiety confers favorable physicochemical properties and stability against forms of degradation to the liquid adsorbent.

The presence of an ether group also increases the interaction with water, thereby increasing miscibility and water capture. An amine functionalized polyether presents one or more active amine groups and a central (poly)ether moiety that improves a number of properties relevant to the invention within a single compound. The liquid absorbent is preferably composed of a pure polyether amine, i.e. without dilution in a solvent. However, the liquid absorbent may also comprise an etheramine as defined above in a non-aqueous solvent. The solvent should be a non-aqueous solvent otherwise the hygroscopic properties of the absorbent would be adversely affected. The liquid absorbent is hygroscopic at the prevailing ambient conditions, so that water is always co-absorbed with the carbon dioxide and water is not lost, although under fast changing weather conditions a temporarily loss of water may occur.

A minimum of 2.8 moles or more of non-tertiary amines, preferably primary amines, per kg unloaded absorbent is needed for viable direct air capture in a continuous process in view of the typical flow of absorbent droplets over the wires in the absorption chamber. The effectiveness of direct air capture in extracting CO; from ambient air, wherein CO. has a low partial pressure, depends on the reactivity of the amine groups towards CO: molecules. The reactivity of an amine group towards CO: may be expressed by the acid dissociation constant (pKa). Preferably the pKa is 9 or more, such as 10 or more. The total loading capacity of the liquid adsorbent is dependent on the quantity of ‘active’ amine groups per volume or weight.

In the invention the loading capacity for viable air capture using a wire column is set by the moles of non-tertiary, preferably primary amines, > 2.8 per kg unloaded absorbent. A practical upper limit is about 22 moles of non-tertiary amines per kg unloaded absorbent. More preferably primary amines are in the range of 5-12 moles per kg unloaded absorbent.

Continuous direct air capture with a liquid absorbent requires large volumes of air to pass through the absorption chamber in contact with the wire supported liquid absorbent. When using a relatively volatile absorbent such as monoamines like monoethanolamine (MEA), evaporation of the volatile absorbent occurs resulting in loss of absorbent. Less volatile absorbents, although less susceptible to evaporation, show an increased viscosity upon capturing carbon dioxide, e.g. in the order of several Pa.s which is about 1000-10000 times higher than water. Formation of carbamate salts upon capturing carbon dioxide, even in low amounts, by mono- and diamines, like diethanolamine (DEA) and triethylamine (TEA), both having a low vapour pressure, which salts solidify, crystalize and/or precipitate, may also occur, thereby disturbing the process operation. High viscosity of the liquid adsorbent adversely effects the mass transfer and also heat transfer. The viscosity of these less volatile amines could be reduced by dilution with a suitable solvent like water. Due to the large volumes of ambient air passing through the absorption chamber in contact with the absorbent water would evaporate in significant amounts and additional water would be needed to make up for the water loss. Water is scarcely available in the sunny regions and countries, where the method according to the invention can be performed using solar energy. The present method can also be performed using normal power grid or energy derived from other natural sources, like wind power and geothermal energy. To avoid loss of water the liquid absorbent according to the invention is hygroscopic. Thus the water vapour pressure in the liquid absorbent is nearly always lower than the equilibrium vapour pressure at the prevailing ambient conditions. The liquid absorbent entering the absorption chamber is hygroscopic with respect to ambient air, so that at the ambient humidity conditions the liquid absorbent will always gain water from and will not lose water to the flow of ambient air in the absorption chamber, even in dry climates.

The etheramine has a vapour pressure equal to or lower than 0.1 Pa at room temperature, preferably 0.01 Pa or less. These etheramines can be charged easily with carbon dioxide, thereby showing a ionic behaviour due to formation of at least one carbamate group or a protonated group, which species have very low vapour pressure. Thus as the pure absorbent absorbs CO, the vapour pressure of the (partially) loaded absorbent decreases. Thus the at least partly loaded etheramines are even less susceptible to evaporation. Therefore advantageously a part of the collected liquid absorbent obtained in step c) may be directly recycled to step a). Additionally although viscosity increases upon loading with carbon dioxide and water, the etheramines maintain their liquid state, thereby allowing continuous direct air capture with a liquid adsorbent.

As explained hereinbefore, evaporation of the liquid absorbent is to be suppressed in order to avoid loss of absorbent. Evaporation rate of the etheramines is dependent inter alia on the molecular weight. Generally, compounds with higher molecular weight have a lower vapor pressure in ambient air, and therefor are less susceptible to evaporation under the prevailing conditions. However, compounds with higher molecular weight intend to be more viscous under the prevailing conditions. In view thereof preferably the average molecular weight (My) of the etheramine is 120-600 g/mol, more preferably 180-500 g/mol.

The viscosity is dependent on ambient temperature, but also CO: and HO content have an effect. Generally uptake of CO: will increase the viscosity, while incorporation of H2O will reduce the viscosity. As the prevailing conditions change during a day, in particular in sunny regions, a practical operating window for the viscosity is 0.05-10 Pa*s, more preferably the viscosity is in the range of 0.1-2 Pa*s.

The viscosity of the etheramine, water hygroscopicity and capture rate thereof can be adjusted by a non-aqueous solvent. Advantageously the non-aqueous solvent has a low vapour pressure at ambient conditions, is inert with respect to the etheramine, and non- harmful to the environment. Polyethylene glycol like PEG200 is an example thereof. Adding

PEG also reduces the typical desorption temperature, thereby lowering the thermal degradation of the etheramine absorbent. Typically, if present the non-aqueous solvent is comprised in an amount of 5-75 wt.%.

The etheramines used as absorbent in the method according to the invention are more stable than secondary or tertiary amines without an ether group. The etheramines are less susceptible to thermal degradation and to oxidative degradation.

Thermal degradation occurs mainly at higher temperature, e.g. 110-140 °C in the absorbent liquid hold-up of the desorption section.

Degradation would affect the absorption capacity and the lifetime of the liquid absorbent. For the same reason of limiting degradation the components. of at least the desorption section are made from suitable materials, e.g. stainless steel and/or plastics.

Preferably, the etheramine comprises a polyetheramine, more preferably selected from the group consisting of 4,7,10-trioxa-1,13-tridecanediamine (Formula 1)

NN Np A TN TN

HNT TOG NN Hg (Formula 1),

OHy CHa (Formula 2), wherein x is 2-7,

T 3 fd LOY bel OG A

N nT ZW |p I Pu 2 - B! .

My (Formula 3), wherein x+y+z=5-6. 4,7,10-Trioxa-1,13-tridecanediamine (Formula 1; CAS Number: 4246-51-9) (aka 1,13- diamino-4,7,10-trioxatridecane) having a molecular weight of 220.31 g/mol and about 9.1 moles of primary amines per kg unloaded absorbent is commercially available, from Sigma-

Aldrich.

Examples of a difunctional polyetheramine having Formula 2 include Jeffamine® D-230 (x = 2.5) having an average molecular weight of about 230 g/mol and about 8.7 moles of primary amines per kg unloaded absorbent, and Jeffamine® D-400 (x = 6.1) having an average molecular weight of about 430 g/mol and about 4.7 moles of primary amines per kg unloaded absorbent.

An example of a trifunctional polyetheramine having Formula 3 is Jeffamine® T-403 (x +y + z = 5-6) having an average molecular weight of approximately 440 g/mol and about 7.5 moles of primary amines per kg unloaded absorbent. 4,7,10-Trioxa-1,13-tridecanediamine (Formula 1} is the most preferred etheramine for use in the method according to the invention.

Desorption

In step c) the liquid absorbent loaded with carbon dioxide and water is collected at the bottom of the absorption chamber and in step d} passed to a desorption section, where at elevated temperature and/or reduced CO: partial pressure the carbon dioxide is desorbed from the liquid absorbent and collected. Water is desorbed as well. Preferably desorption is performed as a thermal swing at atmospheric pressure.

Advantageously in step e) the flow of liquid absorbent loaded with carbon dioxide and water is subjected to an elevated temperature, such as 80 °C or more and/or a reduced carbon dioxide partial pressure, e.g. 0.5 bar or less, such as 0.25 bar or less, preferably both in order to avoid loss of liquid absorbent and to allow practical production rates. The total system pressure is preferably atmospheric pressure (1 bar).

The collected carbon dioxide may be stored permanently, e.g. in deep geological formations.

Preferably the collected carbon dioxide is used in other applications, optionally after temporary storage.

In an advantageous embodiment in collecting step f) water is also collected as a separate product stream, which can be used e.g., in the electrolysis of water for the generation of hydrogen and/or as a water source in dry climates.

In the absorption chamber the etheramine absorbent will reach water equilibrium with the ambient air passing through the absorption chamber. In the desorption section water is continuously stripped from the loaded absorbent, which is advantageously collected. Thus there is no loss of water to the environment. As the ambient conditions typically fluctuate, the absorbents may temporarily lose some water, but on average water is captured.

In an embodiment the desorption is performed in a multistage distillation column provided with a reboiler. In this embodiment the carbon dioxide and water loaded liquid absorbent comprising a mixture of (poly)etheramine, CO. and water, is passed from the absorption chamber to a multi-stage distillation column for desorption. The vapour pressures of the liquid absorbent, water and CO: are very different. E.g. at room temperature the vapour pressures of the above preferred polyetheramine absorbents is negligible, H2O: 2400 Pa, and CO:: 6000.000 Pa respectively. Therefore, separation by multi stage distillation of the three phases is relatively straightforward. Compared to flash-separation desorption, distillation has several advantages: the energy consumption is significantly less than in single stage flash separation; the separation purity is many orders higher; absorbent loss is minimal as it will not be evaporated and subsequently lost in the desorption system; desorption of CO; occurs at much lower partial pressure of CO; in the lower stages of the column. Therefore the regeneration process has an overall lower energy consumption. The absorbent also has a longer lifetime, because degradation mechanisms like thermal and oxidative degradation can be avoided or at least reduced in rate.

Adjusting the power in the reboiler allows to achieve a predetermined production ratio of carbon dioxide to water at the top of the column. E.g. 250 mbar CO; and 750 mbar H.O produces a production ratio H20/CO: of about 3:1.

After desorption the liquid absorbent is returned to the absorption chamber.

In the continuous method heat exchange between the flow of liquid absorbent loaded with carbon dioxide and water to the desorption section and the recycled flow of desorbed absorbent to the absorption chamber in order to at least partially cool the recycled flow to ambient temperature and in order to preheat the loaded flow can be easily performed.

If desired, the method according to the invention may be performed in a multiple pass operation, wherein partially loaded liquid absorbent is recycled from step c) back to step a).

Captured carbon dioxide and water

The carbon dioxide as collected from the desorption section can be stored as such. E.g. the captured carbon dioxide may be stored in a geological formation for fixing carbon dioxide.

The carbon dioxide as collected is also available for further processing,. E.g. the carbon dioxide recovered from the ambient air can be further processed, optionally after condensation of any water therefrom in a condenser. In a preferred embodiment the collected carbon dioxide is allowed to react with hydrogen, derived from electrolysis of water, preferably water collected as a separate stream in the desorption step, into methanol using a catalyst.

Alkaline electrolysis of water, preferably water recovered from the ambient air using the method according to the invention, results in hydrogen and oxygen. The recovered carbon dioxide is reacted with hydrogen over a catalyst bed. Examples of catalysts include Cu or

Cu/ZnO on supports like Al203, TiO2, ZrO2 or combination thereof, optionally in combination with CrO; and/or Ga>Os:. Raney-Cu catalysts are another example. The methanol and water produced can be separated from the reactants by condensation. Methanol and water can be separated in a further separation unit, e.g. a distillation device. Advantageously waste heat derived from the electrolysis of water is used as a source for heating the carbon dioxide loaded liquid absorbent in the desorption step.

Further applications that are contemplated are conditioning the climate, in particular by CO. addition, in greenhouses for growing plants, in preparing carbonated beverages and production of synthetic fuels..

Advantageously, the energy required for performing the steps is supplied by renewable energy sources, e.g. by a solar panel, such as a photovoltaic solar panel, or a solar thermal collector. Waste heat regardless of its origin may also be used as energy source. Solar thermal vacuum tubes can be used as a low cost heat-source for desorption. These tubes can effectively heat up to a temperature of about 120 °C above ambient temperature, which temperature is more than enough for desorption of the CO: from the liquid absorbent. Other renewable energy sources like wind power and geothermal energy can also be applied.

Advantageously waste heat derived from the electrolysis of water is used as a source for heating the carbon dioxide loaded liquid absorbent in the desorption step.

Direct air capturing device

The process according to the invention is advantageously performed in small-sized, lightweight equipment, allowing a dynamic operation using natural energy sources, like solar energy from one or more solar panels as power source during a day, taking into account the day/night rhythm and varying weather conditions like clouds, with short times to start up and to reach steady state operation. For heating the liquid absorbent loaded with carbon dioxide in the desorption section, waste heat derived from the electrolysis of water can function as an additional energy source.

The method according to the invention can be performed using an absorption chamber that is defined by a housing having an intake for ambient air and an outlet for at least partially carbon dioxide depleted air, preferably arranged at an opposite, optionally higher, position (in view of crossflow and counterflow respectively), wherein a plurality of wires are arranged in the absorption chamber configured for guiding liquid absorbent droplets by gravity, wherein the ambient air passes along a flow path from the intake to the outlet in contact with the liquid absorbent droplets on the plurality of wires, a distributor for forming droplets of the liquid absorbent at each of the plurality of wires, and a collector for collecting carbon dioxide and water loaded liquid absorbent droplets at the bottom of the wires, wherein the collector is in fluid connection with the desorption section, and the desorption section having inlet for the loaded fluid absorbent and an outlet for desorbed fluid absorbent and an outlet for collecting carbon dioxide is provided with heating means and/or partial pressure reducing means, and wherein the outlet for desorbed fluid absorbent is in fluid connection with the distributor of the absorption chamber.

Advantageously the desorption step is performed by multi-stage distillation.

In a further aspect the invention relates to a preferred embodiment of a direct air capturing device for recovering carbon dioxide from ambient air, preferably for use in the method according to the invention, wherein the device comprises an absorption chamber for contacting a flow of ambient air, wherein the absorption chamber is defined by a housing having an intake for ambient air and an outlet for at least partially carbon dioxide depleted air, wherein a plurality of wires are arranged in the absorption chamber configured for guiding liquid absorbent droplets by gravity, wherein the ambient air passes along a flow path from the intake to the outlet in contact with the liquid absorbent droplets on the plurality of wires, a distributor for forming droplets of the liquid absorbent at each of the plurality of wires, a collector for collecting carbon dioxide and water loaded liquid absorbent droplets at the bottom of the wires, a desorption section having a feed for the carbon dioxide and water loaded liquid absorbent and an outlet for desorbed liquid absorbent and an outlet for collecting carbon dioxide, the desorption section being provided with heating means and/or partial pressure reducing means, wherein the collector is in fluid connection with the desorption section and wherein the outlet for desorbed fluid absorbent of the desorption section is in fluid connection with the absorption chamber, preferably wherein the distributor comprises a bottom plate having through holes and droplet forming nozzles for each wire, through which the respective wire extends, said droplet forming nozzle comprising a restriction part configured for introducing a pressure drop to homogenize the liquid absorbent flow between wires, a nozzle at the lower face of the bottom plate with a pocket part having a cross-section larger than the restriction part at the nozzle base and a nozzle tip, wherein the nozzle has an at least partly open lateral side, and the open sides of neighbouring nozzle do not face one another.

In a preferred embodiment of this type of distributor these open sides of neighbouring nozzles face in the same direction. In this embodiment the bottom of the distributor has a number of through-holes corresponding to the number of wires. Each through-hole is provided with a droplet forming nozzle, through which the respective wire extends. In a preferred embodiment adroplet forming nozzle comprises a flow controlling part having a restricted cross-section for the flow of liquid absorbent. This part generates a small pressure drop that causes a uniform flow {about the same amount) to each wire. Downstream of this flow restricting part (as seen in the downward flow direction of the liquid absorbent) at the base of the nozzle a wider pocket part having a larger cross section than the restricting part is arranged. This pocket part is filled with the liquid absorbent and forms a growing droplet until gravity is larger than the capillary forces. The droplet thus formed is released from the pocket part and attaches itself to the wire and exits the nozzle tip and travels further downwards along the respective wire. The pocket part also prevents a droplet from moving along the bottom side of the bottom of the distributor that forms the ceiling of the absorption chamber. Thus recombination with other droplets being formed is prevented. The droplet forming nozzle has an open lateral part that is configured for preventing pressure build-up inside the nozzle by the liquid absorbent flow. In order to prevent ready recombination of droplets being formed in adjacent nozzles the open sides of neighbouring nozzles do not face one another thereby creating the path that a droplet would have to travel along the bottom side of the bottom before contacting another droplet as long as possible.

In another preferred embodiment the device comprises at least one upper header module in the distributor and one lower header module in the collector, and one end of a wire length is attached to one of both modules and wound multiple times from one header module to the other header module thereby forming individual wires extending through the absorption chamber between the header modules and the other end of the wire length is attached to one of both modules, as explained above.

In an embodiment the carbon dioxide outlet of the desorption section is connected to a carbon dioxide compressor configured for controlling the flow rate of carbon dioxide through the outlet such that the pressure in the desorption section is maintained at the ambient pressure.

Advantageously the device also comprises a heat exchanger configured for heat exchange between the flow of liquid absorbent loaded with carbon dioxide and water and the flow of carbon dioxide desorbed absorbent.

Preferably the desorption section comprises a multistage distillation column, provided with a reboiler for heating a partially recirculating bottom product flow.

In a further preferred embodiment the reboiler comprises an overflow-syphon element configured for overflowing desorbed liquid absorbent back to the distributor of the absorption chamber. At appropriate arrangement the provision of an overflow-syphon element allows to dispense with the pump and valves for recycling the desorbed liquid absorbent to the distributor.

Preferably a condenser is provided for condensing water from the top product flow of the desorption section, more preferably the multistage distillation column.

Detailed description of the drawings

The invention is further illustrated by the attached drawings.

In Fig. 1 an embodiment of a device for performing the method according to the invention is shown, wherein an absorption chamber is indicated by reference numeral 10. The absorption chamber 10 is contained within a housing 12, which is provided with a inlet 14 (n this counterflow configuration at a lower position) for entering ambient air from the environment and an opposite upper outlet 16 at a higher position for discharging air to the environment, typically provided with a fan 17 for drawing air from the inlet 14 through the chamber 10 to the outlet 16. In this embodiment a plurality of parallel and spaced apart wires 18 as droplet guiding elements (show as broken lines; see also Fig. 2) are vertically arranged in the housing 12 between a distributor 20 and collector 22. The distributor 20 at the top of the chamber 10 feeds and distributes an etheramine liquid absorbent to the upper ends of the wires 18 and forms a series of individual droplets thereon. During travelling down (indicated by arrow A} along a wire 18 a droplet contacts the ambient air flow passing through the absorption chamber 10 between the wires 18. The etheramine droplet absorbs carbon dioxide and water from the ambient air flow. At the bottom end of the wires 18 the etheramine droplets now loaded with carbon dioxide and water are collected in the collector 22 that is provided at the bottom end of the housing 12. In the multiple pass embodiment shown the absorbent is recycled from the outlet 24 of the collector 22 via return conduit 23 provided with pump 25 to the inlet 27 of the distributor 20. The outlet 24 of the collector 22 is also connected to the inlet 26 of a desorption chamber 28 via conduit 30 that is provided with pump 32. Thus the absorbent is continuously recycled over the wires 18 to capture carbon dioxide and water. As the capture in a single pass is relatively low, the load and concentration of the etheramine absorbent is practically the same in the distributor and in the collector. A part of the outflow of the collector 22 is drained to the desorption 28 for regeneration thereof.

The desorption chamber 28 is provided with a heater 34 for heating the desorption chamber 28 and optionally a vacuum pump 36 for reducing the pressure therein. Preferably the total desorption is performed at ambient pressure. Then the pump 36 is superfluous. Carbon dioxide and water desorb from the liquid absorbent in desorption chamber 28 and are collected via outlet 38 and pressurized using compressor 40. The compressor 40 controls the flow rate out of the stripping desorption chamber 28 such that the pressure is maintained essentially the same as ambient pressure. The vacuum pump 36, if present, and compressor 40 may be combined into a multistage compressor. The desorbed liquid absorbent exits the desorption chamber through outlet 44 and is discharged through-overflow syphon (not shown) by gravity and recycled via return conduit 46 to the collector 22. Typically, the hot desorbed liquid absorbent flow is heat exchanged with the flow of loaded liquid absorbent in a heat exchanger 50, thereby preheating the loaded liquid absorbent and cooling the desorbed liquid absorbent.

For subatmospheric operation in the desorption chamber 28 in addition to the vacuum pump 36 a pump 48 in the return conduit 48 is installed and pump 32 is replaced by a valve. For operation at pressures above ambient using pump 32 the pump 48 is replaced by a valve.

Fig. 2 shows a crossflow arrangement of the flow path of ambient air in the spaces between adjacent wires 18 with respect to the downwardly travelling liquid absorbent droplets 52 (see arrow A) over the wires 18. In order to arrange the individual wires 18 a long wire length is wounded multiple times (only few are shown) from an upper header module 54 having openings 55 of the distributor 20 to a lower header module 56 having openings 57 of the collector 22 back to the upper header module 54. The ends 58 of the long wire length are fastened to one of the header modules 54 or 56.

Fig. 3 A and B show an embodiment of a droplet forming nozzle 60 of the distributor 20. The distributor 20 comprises a bottom 82 (Fig. 1) having a through-hole 64 for each wire 18. Each through-hole 64 is provided with a droplet forming nozzle 60, containing the wire 18. In the embodiment as shown a droplet forming nozzle 60 comprises a flow controlling part 66 having a restricted cross-section. This part 66 generates a small pressure drop ensuring that each wire is provided with more or less the same flow of etheramine liquid absorbent.

Downstream of this part 66 (as seen in the downward flow direction of the liquid absorbent) a wider pocket part 88 having a larger cross section than the part 66 is arranged allowing the liquid absorbent to form a growing droplet until gravity is larger than the capillary forces. The droplet thus formed exits the nozzle tip 70 and starts to travel downwards along the respective wire 18. The pocket part 68 also prevents a droplet from moving along the bottom side of the bottom 62 of the distributor 20 that forms the ceiling of the absorption chamber 10 and recombination with other droplets being formed. The droplet forming nozzle 60 has an open lateral part 72 that is configured for preventing pressure build-up inside the nozzle by the liquid absorbent flow. As shown the open lateral parts 72 of the droplet forming nozzles 60 all face in the same direction thereby creating the path that a droplet would have to travel along the bottom side of the bottom 52 before contacting another droplet as long as possible.

Fig. 4 shows an embodiment of a process diagram for conversion of carbon dioxide and water captured from ambient air into methanol using a direct air capture method according to the invention. Water is subjected to alkaline electrolysis and produces hydrogen. The carbon dioxide and hydrogen are catalytically converted into methanol. The produced methanol and water are separated, e.g. by distillation. The processing units are powered by energy from solar panel 78. Additionally waste heat from the water electrolysis is used to heat the liquid absorbent in the desorption step of the direct air capture.

Fig. 5 shows an another embodiment of a device for performing the method according to the invention, having a configuration similar to Fig. 1, except that the desorption section is a multistage distillation column. An absorption chamber 10 is contained within a housing 12, which is provided with a lower inlet 14 for entering ambient air from the environment and an opposite upper outlet 16 for discharging air to the environment, provided with a fan 17 for drawing air from the inlet 14 through the chamber 10 to the outlet 16. A distributor 20 at the top of the chamber 10 feeds and distributes the liquid absorbent to the wires 18. At the bottom of the chamber 10 a collector 22 for the liquid absorbent that has been loaded with carbon dioxide and water from the ambient air during its travelling (indicated by arrow A) by gravity as droplets over wires 18 is provided. The outlet 24 of the collector 22 is connected via heat exchanger 50 to the inlet 26 of the multistage distillation column 80 via conduit 30 that is provided with valve 32, through which the loaded liquid absorbent is fed. Heat is provided by areboiler 82, which heats and recirculates a partial flow of the desorbed liquid absorbent as bottom product derived at outlet 44 of the column 80. The vapour top products, CO: and H20, are removed from the top of the column 80 and water is condensed in condenser 84. The water thus separated is partially fed back to the column 80, while the remaining water is recovered through conduit 86. The CO: flow from the condenser 84 is compressed in compressor 40 and collected. The desorbed liquid absorbent is recycled via return conduit 46, pump 48 and heat exchanger 50 to the distributor 20. The pump 48 can be dispensed with if the reboiler 82 is provided with an overflow-syphon (not shown) connected to the distributor 20. For multipass operation a part of loaded absorbent may be directly recycled via conduit 90 from the collector 22 to the distributor 20 or via a separate return conduit as shown in the embodiment of Fig. 1.

Fig. 6 shows the moles of sorbent evaporated (mol/year/m3/hr) as a function of the vapor pressure (Pa).of the absorbent. As appears, a sharp increase occurs at a vapor pressure of O. 1 Pa. This means that e,g, in a wired column using an absorbent having a vapor pressure of about 1 Pa and an ambient air flow of 4500 m3/hr would evaporate about 5800 mol amine per year. In case of absorbents having a vapor pressure of 0.1 Pa and 0.01 Pa respectively, the evaporation loss would be about 580 mol/year, respectively 58 mol/year. To reduce evaporation, in particular in sunny climates for which the method according to the invention is particularly useful, the etheramine absorbent has a maximum vapor pressure of 0.1 Pa or less.

Fig. 7 shows the vapor pressure at various ambient temperatures (20, 30 and 40 °C respectively) for various amine absorbents. As can be seen conventional amines like methyl monoethanolamine (MMEA), dimethylmonoethanolamine (DMMEA), diethylmonoethanolamine (DEMEA), diglycolamine (DGA), 2-amino-2-methyl propanol (AMP), monoethanolamine (MEA) used in industry for cleaning flue gases have a high vapor pressure at these temperatures. The two examples of a polyetheramine used in the carbon dioxide capture from ambient air, 4,7,10-trioxa-1,13-tridecanediamine (‘diamino trioxadecane’) and Jeffamine D230 have a much lower vapor pressure at 20 °C. In direct air capture scrubbers to collect evaporated amines due to the large amount of ambient air that flows over the absorbent, are not feasible. Solid amines having a low vapor pressure at the prevailing conditions cannot be used in a continuous method using a liquid absorbent.

Fig. 8 shows the viscosity (Pa*s) of various absorbents at 30 °C and RH=50%. The example of loaded polyetheramine of the invention (4,7,10-trioxa-1,13-tridecanediamine) has a viscosity of about 0.8 Pa*s, a value which can be reached for tetraethylene pentamine (TEPA) in a polyethylene glycol (PEG) solution at a ratio TEPA:PEG = 1:2,5.

Fig. 9 illustrates the thermal decay rate of several absorbents at 120 °C. As can be seen the loss of the example of polyetheramine according to the invention {4,7,10-trioxa-1,13- tridecanediamine) as a result to the exposure at elevated temperature is much lower.

Fig. 10 depicts the carbon dioxide capture rate (normalized graph) as function of time (hrs) in a climate chamber at ambient conditions for TEPA and the example of polyetheramine according to the invention (4,7,10-trioxa-1,13-tridecanediamine). As can be seen the loading of the polyetheramine is almost two times faster than that of TEPA.

Claims

CONCLUSIONS

A method of capturing carbon dioxide and water from ambient air, comprising the steps of a) flowing liquid absorbent droplets (52) downwards along a plurality of wires (18) in an absorption chamber (10) by means of gravity; b) flowing ambient air through the absorption chamber (10) in contact with the liquid absorbent droplets (52) on the plurality of wires (18) to capture carbon dioxide and water from the ambient air at ambient temperature and pressure, thereby obtaining liquid absorbent droplets (52) loaded with carbon dioxide and water; c) collecting the carbon dioxide and water loaded absorbent droplets (52); d) directing the stream of loaded liquid absorbent obtained in step c) to a desorption section (28; 80); 8) desorbing carbon dioxide and water from the stream of loaded liquid absorbent in the desorption section (28; 80) at elevated temperature and/or reduced partial pressure of carbon dioxide compared to the ambient temperature and pressure conditions of step b), thereby obtaining a stream of desorbed absorbent, carbon dioxide and water; f) collecting the carbon dioxide obtained in step c); 9) recycling the stream of desorbed absorbent from the desorption section (28, 80) to step a). wherein the liquid absorbent is an ether amine comprising at least one amine group and one ether group, or a solution thereof in a non-aqueous solvent, wherein the liquid absorbent has 2.8 moles or more of non-tertiary amines per kg of unladen absorbent, wherein the liquid absorbent is hygroscopic in ambient air, and wherein the unladen liquid absorbent has a vapour pressure of 0.1 Pa or less at 20°C.

2. A method according to claim 1, wherein the liquid absorbent comprises a polyetheramine with primary amines, preferably with 5-12 moles of primary amines per kg of unladen absorbent, or a solution thereof in a non-aqueous solvent.

A method according to any one of the preceding claims, wherein the viscosity of the liquid absorbent under the operating conditions is in the range of 0.05-10 Pa´s, preferably in the range of 0.1-2 Pa´s.

A method according to any preceding claim, wherein the average molecular weight (Mw) of the etheramine is in the range of 120-800 g/mol, preferably in the range of 180-500 g/mol.

A method according to any one of the preceding claims, wherein the etheramine is selected from the group consisting of 4,7, 10-trioxa-1,13-tridecanediamine (Formula 1) HN GG NH (Formula 1), HS TS NH UH CHa (Formula 2), where x is 2-7, 2H 4 Y NMa LO es OH 4 AE CH : pi EE 3 be FE and, AND 3 . Hal A ho rAd Form v Mac” (Formula 3), where x+y+z=5-6.

8. A method according to claim 5, wherein the etheramine is selected from the group consisting of 4,7,10-trioxa-1,13-tridecanediamine (Formula 1) i.e. Kk) = oe N HNT 0 TNT NH (Formula 1),

7. A method according to any preceding claim, wherein the liquid absorbent comprises a non-aqueous diluent, preferably in an amount of 5 - 75 wt%.

The method of claim 5, wherein the non-aqueous diluent comprises PEG having a molecular weight in the range of 150-400 g/mol.

9. A method according to any preceding claim, wherein in step e) the stream of liquid absorbers loaded with carbon dioxide and water is subjected to an elevated temperature, preferably a temperature of 80°C or more, more preferably at ambient pressure.

A method according to any preceding claim, wherein a portion of the collected liquid absorbent loaded with carbon dioxide and water, obtained in step ¢), is returned to step a).

A method according to any preceding claim, wherein in step g) the stream of laden liquid undergoes a heat exchange with the stream of desorbed absorbent.

A method according to any preceding claim, wherein the energy required for performing the steps is supplied by renewable energy sources, preferably at least one solar panel and/or at least one wind turbine.

A method according to any preceding claim, wherein the collected water is subjected to electrolysis to produce hydrogen and oxygen.

A method according to any preceding claim, wherein the collected carbon dioxide is reacted with hydrogen from the electrolysis of water to form methanol using a catalyst.

15. A method according to claim 13 or claim 14, wherein the residual heat from the electrolysis of water is used to heat the desorption section (28,

80).

A method according to any one of the preceding claims 1 to 13, wherein the collected carbon dioxide is stored for further processing thereafter in climate conditioning in greenhouses for growing plants, in the preparation of carbonated beverages, in the production of synthetic fuels and/or stored in a rock formation for fixing carbon dioxide.

A method according to any one of the preceding claims, wherein the absorption chamber (10) is defined by a housing (12) having an inlet (14) for ambient air and an outlet (16) for air at least partially depleted of carbon dioxide, the absorption chamber (10) having disposed therein a plurality of wires (18) configured to guide liquid absorbent droplets (52) by gravity, the ambient air passing along a flow path from the inlet to the outlet in contact with the liquid absorbent droplets (52) on the plurality of wires (18), a distributor (20) for forming droplets (52) of the liquid absorbent on each of the plurality of wires (18), and a collector (22) for collecting carbon dioxide and water laden droplets (52) of the liquid absorbent from the underside of the wires (18), the collector (22) being in flow communication with the desorption section (28, 80), and the desorption section (28, 80) having an inlet (26) for the carbon dioxide-laden liquid absorbent and an outlet (44) for desorbed liquid absorbent and an outlet (38) for collecting carbon dioxide is provided with heating means (34) and/or partial pressure reducing means (38), and wherein the desorbed liquid absorbent outlet (44) is in flow communication with the distributor {20} of the absorption chamber (10).

18. A direct air capture apparatus for recovering carbon dioxide and water from ambient air, preferably for use in the method according to any preceding claim, the apparatus comprising an absorption chamber (10) for contact with a stream of ambient air, the absorption chamber (10) being defined by a housing (12) having an inlet (14) for ambient air and an outlet (186) for air at least partially decarbonized, a plurality of wires (18) arranged in the absorption chamber (10) configured to guide liquid absorbent droplets (52) by gravity, the ambient air flowing along a flow path from the inlet to the outlet in contact with the liquid absorbent droplets on the plurality of wires, a distributor (20) for forming droplets (52) of the liquid absorbent on each of the plurality of wires (18), a collector (22) for collecting droplets (52) laden with carbon dioxide and water from the liquid absorbent at the bottom of the wires (18), a desorption section (28, 80) having an inlet (26) for the liquid absorbent loaded with carbon dioxide and water and an outlet (44) for desorbed liquid absorbent and an outlet (38) for collecting carbon dioxide, the desorption section being provided with heating means (34) and/or partial pressure reducing means (36),

wherein the collector (22) is in flow communication with the desorption section (28, 80) and wherein the outlet (44) of desorbed liquid absorbent from the desorption section (28, 80) is in flow communication with the distributor (20) of the absorption chamber (10), preferably wherein the distributor (20) comprises a base plate (62) having through holes (64) and droplet forming nozzles (60) for each wire through which the respective wire (18) passes, the droplet forming nozzle (60) comprising a restriction member (66) configured to introduce a pressure drop to homogenize the liquid absorbent flow between the wires, a nozzle at the bottom of the base plate having a bag portion (68) of larger cross-section than the restriction member (66) at the base of the nozzle and a nozzle tip (70), the nozzle having an at least partially open lateral side (72) and the open sides of adjacent nozzles are not opposite each other.

The direct air capture device of claim 18, wherein the open side (72) of each nozzle all point in the same direction.

A direct air capture device according to any one of the preceding claims 18-19, comprising at least one upper header module (54) in the distributor (20) and at least one lower header module (56) in the collector {22}, and wherein one end (58) of a length of wire is attached to one of the modules (54, 56) and is wound multiple times from one header module to the other header module, thereby forming individual wires (18) extending through the absorption chamber between the header modules, and wherein the other end (58) of the length of wire is attached to one of the modules (54, 58).

A direct air capture apparatus according to any one of claims 18 to 20, further comprising a heat exchanger (50) configured for heat exchange between the stream of liquid absorbent loaded with carbon dioxide and water and the stream of absorbent from which carbon dioxide has been desorbed.

22. A direct air capture apparatus according to any one of the preceding claims 18-21, wherein the desorption section (28, 80) comprises a multi-stage distillation column (80) provided with a reboiler (82) for heating a partially recirculating bottoms stream.

The direct air capture apparatus of claim 22, wherein the reboiler (82) comprises an overflow siphon element configured to overflow desorbed liquid absorbent back into the absorption chamber.

A direct air capture apparatus according to any one of claims 18 to 23, wherein the carbon dioxide outlet (38) of the desorption section (28, 80) is connected to a carbon dioxide compressor (40) configured to control the flow of carbon dioxide through the outlet so that the pressure in the desorption section (28, 80) is maintained at ambient pressure.