Patent Application
20250041797
This disclosure relates to systems and methods for direct capture of carbon dioxide in air and calcium hydroxide-based compositions.
CO2 emissions linked to human activities are recognized as being responsible for climate change. Although efforts are being made to decrease the quantity of CO2 released into the atmosphere, there is a growing consensus that decreasing emissions alone will not be sufficient to avoid global temperature increase of more than 1.5° C. compared to pre-industrial era.
There is therefore a need to deploy techniques capable of removing CO2 from the atmosphere. Such techniques are often designated under the generic term carbon dioxide removal technologies (CDR technologies), which includes for instance afforestation, bio-energy with carbon capture and storage (BECCS) and Direct Air Capture (DAC). These technologies can help in capturing and/or storing up to 10 billion tons of CO2 per year by 2050 and are thus recognized as essential means to achieve carbon neutrality.
Direct Air Capture refers to CDR approaches that rely on chemicals that react with atmospheric CO2 and followed by a subsequent step aimed at separating the chemicals and the CO2 in a substantially pure form so that it is compatible with sequestration or use.
Several technological routes have been proposed for DAC and some have reached or are close to reach commercial maturity. However, they come with several techno-economic challenges, such as:
Therefore, there is thus a need for DAC system with reduced capital and operational cost that uses cheap and widely available raw materials to ensure cost efficiency and scalability.
In this regard, quicklime (alternatively hydrated lime) produced from a source of calcium carbonate such as natural limestone, can be used for capturing CO2 according to the following reaction:
CaO+CO2->CaCO3 (Equation 1)
alternatively
Ca(OH)2+CO2->CaCO3+H2O (Equation 2)
The formed carbonate can then be calcined again to produce lime and substantially pure CO2 for use or sequestration:
CaCO3+heat->CaO+CO2 (Equation 3)
The heat necessary for the calcination can be provided by the combustion of fuel. For instance, industrial oxygen can be advantageously used instead of air in order to avoid dilution of the CO2 with nitrogen from the air.
After a purification step, both the CO2 resulting from the decomposition of calcium carbonate and from the combustion of fuel can be sequestered, resulting in net removal of CO2 from the atmosphere.
The produced lime or hydrated lime can then be re-exposed to atmospheric air for subsequent CO2 capture.
Hydrated lime Ca(OH)2 has some advantages compared to quicklime CaO due to its microstructural properties that enable faster and higher conversion of lime to carbonate. Relative humidity has also been identified as n results from a dissolution-precipitation mechanism. For instance N. Koga et al./Ceramics International 41 (2015) 9482-9487 al. reported that no carbonation reaction occurs at 0% relative humidity. More interestingly, it was highlighted that conversion rate plateaued at 40% conversion to CaCO3 when relative humidity was 50%.
The ability of the sorbent to achieve high conversion to carbonate is indeed important to minimize the amount of sorbent required to capture a given quantity of CO2. Moreover, unreacted calcium hydroxides induces an energy penalty during the calcination step:
The standard enthalpy of de-hydration of Ca(OH)2 is 65 kJ/mol. It should be noted that for each mol of de-hydrated Ca(OH)2 1 mol of H2O remains as steam (i.e., latent heat of vaporization is not recovered), therefore increasing the dehydration enthalpy to about 65+2,256 kJ/g*18 g/mol=106 kJ/mol.
The present disclosure aims to provide a solution to overcome at least one drawback of the teaching provided by the prior art document.
In particular the present disclosure aims to provide a direct air capture process or sorbents capable of achieving a high conversion ratio, preferably under different types of weather conditions, particularly under arid conditions.
For the above purpose, the present disclosure is directed to a process for direct capture of carbon dioxide in air comprising a process for direct capture of carbon dioxide in air comprising the following steps: providing a calcium hydroxide-based composition; contacting said composition with air so as to capture CO2 contained in said air by transforming at least some of the calcium hydroxide of said composition into calcium carbonate, forming a calcium carbonate-based composition; optionally collecting the calcium carbonate-based composition; optionally extracting at least some CO2 from at least some of the collected calcium carbonate-based composition, preferably via calcination and/or electrolysis, wherein said calcium hydroxide-based composition has a partial pore volume equal to or higher than 0.09 cm3/g, in particular higher than 0.1 cm3/g, said partial pore volume being calculated according to the BJH method for a range of pores having a diameter between 20 and 200 Å in accordance with standard DIN 66134 (February 1998 version); optionally the difference between a total pore volume being calculated according to the BJH method for a range of pores having a diameter of between 20 and 1000 Å in accordance with standard DIN 66134 (February 1998 version) and said partial pore volume being equal to or higher than 0.06 cm3/g, preferably higher than 0.08 cm3/g.
According to specific embodiments of the present disclosure, the process for direct capture of carbon dioxide in air comprises one or more of the following features/steps:
The present disclosure can also be related to a calcium hydroxide-based composition characterized by a partial pore volume equal to or higher than 0.09 cm3/g, in particular higher than 0.1 cm3/g, said pore volume being calculated according to the BJH method for a range of pores having a diameter between 20 and 200 Å in accordance with standard DIN 66134 (February 1998 version); preferably a BET specific surface area greater than 30 m2/g, preferably greater than 40 m2/g, and more preferably greater than 45 m2/g measured according to IS09277 standard (September 2010 version); preferably a BET specific surface area greater than 30 m2/g, preferably greater than 40 m2/g, and more preferably greater than 45 m2/g measured according to IS09277 standard (September 2010 version; wherein said composition (is in the form of a composition with) has a water content above 35% by weight of said composition, preferably at most 85% by weight of at least of said composition, preferably said composition being a flowable or malleable composition such as a milk of lime or putty lime; optionally the difference between a total pore volume being calculated according to the BJH method for a range of pores having a diameter of between 20 and 1000 Å in accordance with standard DIN 66134 (February 1998 version) and said partial pore volume being equal to or higher than 0.06 cm3/g, preferably higher than 0.08 cm3/g.
The present disclosure can also be related to a calcium hydroxide-based composition characterized by: a partial pore volume equal to or higher than 0.09 cm3/g, in particular higher than 0.1 cm3/g said pore volume being calculated according to the BJH method for a range of pores having a diameter of between 20 and 200 Å in accordance with standard DIN 66134 (February 1998 version); preferably a BET specific surface area greater than 30 m2/g, preferably greater than 40 m2/g, and more preferably greater than 45 m2/g measured according to IS09277 standard (September 2010 version); optionally wherein the difference between a total pore volume being calculated according to the BJH method for a range of pores having a diameter of between 20 and 1000 Å in accordance with standard DIN 66134 (February 1998 version) and said partial pore volume is equal to or higher than 0.06 cm3/g, preferably higher than 0.08 cm3/g; wherein said composition is in the form of shaped bodies, wherein the shaped bodies are selected from the group comprising pellets, granules, extrudates, 3D printings or compacts such as tablets or briquettes, preferably said composition having an apparent density lower than 1.4 g/cm3, and optionally lower than 1.1 g/cm3 and preferably higher than 0.8 g/cm3.
The present disclosure can also be related to a calcium hydroxide-based powder composition, said composition having a partial pore volume equal to or higher than 0.09 cm3/g, said pore volume being calculated according to the BJH method for a range of pores having a diameter of between 20 and 200 Å in accordance with standard DIN 66134 (February 1998 version); preferably a BET specific surface area greater than 30 m2/g, preferably greater than 40 m2/g, and more preferably greater than 45 m2/g measured according to IS09277 standard (September 2010 version); optionally wherein the difference between a total pore volume being calculated according to the BJH method for a range of pores having a diameter of between 20 and 1000 Å in accordance with standard DIN 66134 (February 1998 version) and said partial pore volume is equal to or higher than 0.06 cm3/g, preferably higher than 0.08 cm3/g; a weight fraction of Ca(OH)2 of at least 80%, preferably at least 90% on a dry basis; wherein said composition reaches a CO2 content of at least 31% by weight, preferably at least 33% by weight, more preferably at least 37% by weight, in particular at least 41% by weight on a dry basis when carbonated under a test where four samples, namely a first, second, third and fourth sample of said composition are in contact with four predefined CO2 enriched air compositions adapted to simulate an accelerated carbonatation in a weathering chamber, said the CO2 content being the lowest of the four CO2 contents measured under the following conditions:
According to specific embodiments of the present disclosure, the calcium hydroxide-based composition comprises one or more of the following features/steps:
According to specific embodiments of the present disclosure, the calcium hydroxide-based powder composition comprises one or more of the following features:
Aspects of the present disclosure will now be described in more detail with reference to the appended drawings, wherein same reference numerals illustrate the same features.
The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings. The present disclosure may however be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness.
For the process for direct capture of carbon dioxide in air according to the present disclosure, a calcium hydroxide-based composition is provided with a partial pore volume equal to or higher than 0.09 cm3/g, in particular higher than 0.1 cm3/g, said partial pore volume being calculated according to the BJH method for a range of pores having a diameter between 20 and 200 Å in accordance with standard DIN 66134 (February 1998 version); optionally the difference between a total pore volume being calculated according to the BJH method for a range of pores having a diameter of between 20 and 1000 Å in accordance with standard DIN 66134 (February 1998 version) and said partial pore volume being equal to or higher than 0.06 cm3/g, preferably higher than 0.08 cm3/g.
More specifically, the calcium hydroxide-based calcium composition is obtained with the following preparation steps:
The calcium hydroxide-based composition can be provided in the form of a malleable or flowable composition, shaped bodies or powders.
A malleable or flowable composition can be obtained via the above-mentioned preparation directly or indirectly.
In the case of a direct preparation, the malleable or flowable composition is the result of a slaking with a water/lime weight ratio above 1.21 without further dilution or a water/lime weight ratio between 0.75 and 1.2 followed by a dilution. The slaking can be combined with one or more additives.
In the case of an indirect preparation, the malleable or flowable composition is prepared via mixing a dried calcium hydroxide-based powder composition obtained with water/lime weight ratio of between 0.75 and 1.2. The mixing can be combined with one or more additives. The resulting malleable or flowable composition obtained via the slaking or mixing has typically a water content above 35% by weight of said composition, and optionally at most 85% by weight of said composition. A flowable or malleable composition can be a putty lime or a milk of lime.
The malleable or flowable composition can be used as a sorbent to be carbonated in a contactor or as a precursor for a sorbent shaped body. In the latter case, the malleable or flowable composition can be shaped into 3D printings or pellets or other forms obtained by extrusion (e.g. WO1999061373A1). Preferably, the shaped bodies obtained have at least one dimension greater than 3 mm. Preferably a given shaped body has an apparent density lower than 1.4 g/cm3, preferably lower than 1.1 g/cm3 and preferably higher than 0.8 g/cm3. The apparent density characterizes the pore porosity within the particles forming the shaped body but also the intraparticle void volume between the same particles. The intraparticle void volume promotes gas diffusion from the envelope of the shaped body to the pores of the particles forming said shaped body. Optionally, the shaped bodies can be contacted with air or a CO2 rich atmosphere so as to pre-carbonate them and therefore enhance their mechanical strength. Prior to the shaping of the shaped bodies, the malleable or flowable composition can be mixed with at least one element selected from the group comprising support particles, at least one shaping additive, water, or any combination thereof.
A calcium hydroxide-based powder composition obtained with the above-mentioned process with water/lime weight ratio of between 0.6 and 1.2 can directly applied on a contactor surface or be used a precursor for forming shaped bodies. In the latter case, a calcium hydroxide-based powder composition is shaped into pellets, granules, extrudates, 3D printings or compacts such as tablets or briquettes, preferably said shaped bodies having at least one dimension greater than 3 mm. Examples of shaping devices for calcium-based particulates are disclosed in WO2021078878A1, WO2016110572A1, WO2018007634A1, WO2018007630A1. Eventually, the shaped bodies can be contacted with air or a CO2-containing atmosphere so as to pre-carbonate them and therefore enhance their mechanical strength. Advantageously, prior to the shaping the calcium hydroxide powder composition is mixed with at least one element selected from the group comprising support particles, at least one shaping additive, water, or any combination thereof. Preferably a given shape body has an apparent density lower than 1.4 g/cm3, preferably lower than 1.1 g/cm3 and preferably higher than 0.8 g/cm3. The apparent density characterizes the pore porosity within the particles forming the shaped body but also the intraparticle void volume between the same particles. The intraparticle void volume promotes gas diffusion from the envelope of the shaped body to the pores of the particles forming said shaped body.
Typically, a malleable or flowable composition, such as a milk of lime can be used as a coating precursor. The milk of lime is, for this purpose, applied a on a support surface. For instance, the support surface, such as a plate is immersed in a receptacle containing a milk of lime before being extracted thereof. Over time, the malleable or flowable layer will dry and form an adhering layer on the support surface. The calcium hydroxide composition in the layer will carbonate in contact with the CO2 present in the air.
For instance,
Furthermore, a flowable or malleable composition can be a precursor for a sorbent shaped body. One or more of these sorbent shaped bodies can be used for CO2 capture in air. To this end, the shaped bodies are placed in or on a stationary or moving support or containment device selected from a non-exhaustive group comprising: trommel, plate, bucket, pile, tray, filter media, cartridge, grate, tile, wall, brick, carbonated product, net, ground and gabion. Preferably, shaped bodies have a water content of at least 5%, preferably at least 10%, and/or at most 20%, preferably at most 15% by weight of said bodies. A drying step may be required for the shaped bodies obtained from a malleable or flowable composition to reach the above-mentioned water content range.
Moreover, a calcium hydroxide-based powder composition can be placed in or on a stationary or moving support selected from the non-exhaustive group comprising: trommel, plate, bucket, pile, tray, filter media, such as clothes or bags in a bag filter, cartridge, grate, tile, wall, brick, carbonated product ground and net. Preferably, the hydroxide-based powder composition supplied to the support has a water content of at least 5% by weight, preferably at least 10% by weight, and/or at most 20% by weight, preferably at most 15% by weight of said composition. The water content could be lower than 5%. While a reduction of the water content below the threshold of 5% should not be excluded, a minimum water content is advantageous as water facilitates the kinetics of the carbonation process at low temperatures (e.g., 2° C. to 50° C.), which is primarily governed by ionic reactions.
The calcium hydroxide-based powder composition in the form of powders can also serve as a sorbent in a packed bed (e.g., fixed bed or moving bed) or fluidized bed such as a bubbling bed, a spouted bed, a circulating fluidized bed or an entrained bed. Alternatively, small sorbent shaped bodies with dimension lower than 10 mm can also be used in a packed bed or fluidized bed.
A powder-based sorbent composition can also be used for capturing CO2 in air in combination with a filtering media such as clothes or bags in a bag filter. For instance,
A calcium hydroxide-based composition in the form of a malleable or flowable composition, shaped bodies or powders, according the present disclosure can be directly exposed to ambient air or to a conditioned air.
One or more of the following parameters of the conditioned air can be adjusted in order to enhance the degree of conversion and, optionally the kinetics thereof: an air flow rate/speed, an air temperature, an air relative humidity, and an air absolute humidity.
The embodiment of
Similarly, the characteristics of the sorbent can be adjusted in order to optimize the conversion by modifying at least one of following: the flow rate a calcium hydroxide-based composition, the residence time of the calcium hydroxide-based composition, the inventory of a calcium hydroxide-based composition and/or an absolute water content inside the calcium hydroxide-based composition.
Theses parameters (air characteristics and/or sorbent characteristics) can be adjusted by one of the following control means, such as valves, guiding blade, fans, blowers, humidifiers, coolers, and/or heaters. Equally, means for forming ridges on the surface of the powder composition or for stirring the composition (e.g. with beater) can be employed to homogenize said calcium hydroxide, thereby preventing stratification.
Preferably, the calcium hydroxide-based sorbent composition can be placed in an air flow channel that comprises an air flow inlet and an air flow outlet. In this setup, one or more of the aforementioned conditioned air characteristics are adjusted based on element such as weather conditions, particularly an ambient air temperature and/or an air relative humidity as measured or estimated at the air flow inlet. The carbonation process can be monitored by considering the carbonate content in said composition at one or more locations and/or the difference in CO2 concentration between the air flow inlet and flow outlet, in particular the air flow should be adapted according to capture rate at a given time. A parameter that commonly affects carbonation is humidity level, and as such, the humidity of the air in contact with the sorbent composition. This parameter can be controlled to maintain a high level of humidity. Alternatively or additionally, the sorbent can be humidified in a controlled manner to regulate its moister content.
The embodiment according to
The calcium hydroxide-based sorbent composition is intended to be exposed to temperature falling in the range of 2° C. to 50° C., preferably within the range 15° C. to 50° C. and/or relative humidity levels falling within the range of 10% to 95%, preferably 70 to 100%. To achieve this, the contactor(s) can be strategically located in areas with suitable weather conditions that provide optimal carbonatation. If the desired weathers conditions cannot be guaranteed in the available locations, air conditioning can be implemented to compensate for climatic variations and maintain the humidity and temperature within appropriate ranges, in particular with high relative humidity (70% to 100%) and/or low temperatures (5° to 15° C.). In cases where the DAC locations (usually driven by sequestration capacities) are unsuitable due to climate constraints, limited access to energy sources, the calcium hydroxide-based composition according to the present disclosure demonstrates surprising adaptability for CO2 capture in air with low relative humidity and high temperature, making it efficient even in arid climates.
It should be emphasized that the calcium hydroxide-based composition according to the present disclosure also performs well for carbonation in a rich CO2 atmosphere such as flue gas. The carbonation reaction is typically effective at high temperatures, ranging from 450° C. up to 600° C. This type of carbonation is commonly referred to as high-temperature carbonation, in contrast to the low/ambient temperature (e.g. 2° C. to 50° C.) carbonation encountered in CO2 capture from air (also known as Direct Air Capture). The composition can also be used for example for flue gases at temperature higher than ambient but still moderate, for example above 100 or 120° C. Furthermore, when appropriate in the context, the term “air” used herein can be replaced by “CO2 containing gas”, for example flue gas.
After exposure to air, the carbonate sorbent generally takes the form of powders, agglomerated powders, coated layers, or shaped bodies. Depending on the carbonation conditions, the carbonated sorbent particles may become worn or fused together. It is advantageous to collect the carbonated sorbent once the molar conversion of Ca(OH)2 into CaCO3 reaches a predefined level. The level of conversion can be determined by the CO2 content present in the carbonated composition. To evaluate the conversion level, a sample of the carbonated sorbent can be taken and analyzed in a lab. Alternatively, in-situ monitoring can be implemented using an analyzer to measure the chemical composition of the sorbent directly in or on the contactor in real time or at regular intervals. Additionally, a model-based predictive algorithm can be used to estimate the conversion level based on recorded atmospheric data. Achieving a high level of conversion reduces the energy needed for decarbonation, as any unreacted calcium hydroxide would be unnecessarily heated and de-hydrated in a calciner.
The collected calcium carbonate can be effectively conditioned to increase its calcium carbonate content before undergoing decarbonation to address the aforementioned limitations.
Such conditioning includes at least one of drying, grinding, milling, classifying, dehydroxylating, or purifying the collected calcium carbonate-based composition, or any combination thereof. Specifically, the purification step involves separating some of the unreacted calcium hydroxide from the collected calcium carbonate-based composition. This can be achieved through purification processes such as air classification, leaching, peeling, flotation, or any combination thereof.
Then, the raw, conditioned, or purified carbonate sorbent is decarbonated to be either recycled for further direct capture applications or for another purpose. During the decarbonation process, CO2 is extracted from the collected calcium carbonate-based composition through direct or indirect calcination, electrochemistry, or chemical attack. In indirect calcination (in which combustion is done in a separate chamber and heat passes through a wall to reach the material to be treated), heat can be supplied by the combustion of carbon-neutral fuels, hydrogen combustion, or electric heaters. In direct calcination, heat can be generated by air-based combustion of carbonous fuel/H2. The exhaust gas generated during the process can be treated in a post-combustion CO2 capture system, such as amine gas treating or pressure swing absorption. Oxyfuel firing (using carbonous fuel and/or H2), can also be considered. Alternatively, electrical heat input methods such as plasma or induction can be used. Electrochemistry involves performing electro-dissolution, while in a chemical attack, the carbonated material can react with a strong base such as NaOH or a strong acid such as HCl.
The heat released during the slaking process or the sensible thermal energy in the decarbonated materials can be advantageously recovered in several applications such as for preheating the carbonated materials or for drying the slaked lime. Therefore, it is advantageous to have the hydration unit and the decarbonation unit located in the same facility. This measure would also reduce the transportation and stock duration.
To illustrate the present disclosure, various calcium hydroxide powder compositions were prepared.
As raw materials, an industrial soft burnt quicklime with the following characteristics was used:
The reactivity of quicklime was evaluated using t60 parameter which corresponds to the time needed to raise the temperature of the lime/slaking water system up to 60° C., slaking of the lime being conducted following the protocol described in the standard EN 459-2 § 7.6 (July 2021 version).
The particle size distribution was determined using dry sieving method which consist in dividing the initial material by means of a series of sieves with different aperture sizes and by weighting the fraction of initial material retained on the various sieves.
Chemical composition was measured using ICP-OES (inductively coupled plasma-optical emission spectroscopy).
The CO2 contained in the lime in the form of carbonate was measured according to EN 459-2 § 6.6 (July 2021 version) which consist in releasing gaseous CO2 though a reaction with hydrochloric acid and determined volumetrically.
Different hydrated lime samples were produced by mixing one kilogram of quicklime with a water/lime weight ratio between 0.6 and 1.05 in a laboratory mixer. In some cases, delaying additives (Diethylene Glycol—DEG or Triethanolamine—TEA) were also added.
After completion of the hydration reaction, the residual humidity (free moisture) was determined by measuring the mass loss following heating the samples at 150° C. for 2 hours in a drying oven (EN 459-2 § 6.5 Jul. 2021 version)
The dried product was ground in order to break calcium hydroxide agglomerates and reduce particle size to below 250 μm.
The hydrates obtained were characterized as follows. The BET specific surface area of the powders was measured in accordance with standard IS09277, second Edition of Sep. 1, 2010. The pore volume and pore distribution as a function of pore diameter were calculated based on the step-by-step analysis of the isotherm desorption branch using the BJH method of Barrett, Joyner and Halenda (1951), conventionally used with 77K nitrogen as adsorbent gas. The method is described in standard DIN66134 (February 1998 version). It allows the calculation of pore volume distribution as a function of pore diameter on the assumption that the pores are cylindrical. The pore volume and pore volume distribution were determined for the range of pores having a diameter ranging from 20 to 1000 Å. The results are given below per interval of 100 Å (20-100 Å, 100-200 Å, etc.). On the basis of pore volume distribution determined with the BJH method, the BJH pores size distribution of the pores was also calculated per interval of 100 Å again assuming the pores are cylindrical.
Eleven compositions were tested having the following characteristics:
Samples N° 1 to 5 illustrate the influence of the water-to-lime ratio (and in fine the residual moisture) when no additives are used.
Samples N° 6 to 9 highlight the influence of DEG additive level, with the objectives of assessing the effect of varying BET specific surface area for compositions with a relatively high porous volume in both the 20-200 Å and 200-1000 Å ranges.
Samples N° 10 to 11 illustrate the influence of additive types such as DEG and TEA for an intermediate water-to-lime ratio, with the objectives of producing compositions with high BET specific surface area but a lower porous volume, especially in the range 200-1000 Å
The CO2 capture performances of the different samples were studied by placing a 3 mm layer of hydrated material powder in a set of 150 mm×150 mm×3 mm plastic mold placed in a weathering chamber (Weiss Technik CareEvent C/1400/5/30 CO2).
The weathering chamber is equipped with systems to monitor and regulate temperature, relative humidity and CO2 concentration and two axial fans in order to ensure internal air circulation. The fans have a nominal rotational speed of 1200 rpm and a diameter of 20 cm. The target temperatures and the target relative humidity were selected to represent typical weather conditions. The CO2 concentration was multiplied by around five times the reference natural CO2 concentration (400 ppmv) to accelerate the carbonation process at ambient temperature. It is assumed that the results obtained with an enriched CO2 atmosphere can be extrapolated to atmospheric conditions, considering the low concentration level and narrow range investigated. The temperature, the relative humidity and CO2 concentration are regulated to remain within the accuracy ranges presented in the table below:
Hydrated lime samples were tested in the following conditions:
At the end of the experiments, the CO2 content was measured according to EN 459-2 § 6.6 mentioned above.
It represents the amount of CO2 chemically bound to the solid at the end of the experiment and is therefore proportional to the conversion of the calcium hydroxide into carbonate.
The CaCO3 content (wt %) can be determined from the CO2 content (wt %) with the following formula (1) based on the atomic masses:
The molar conversion of Ca(OH)2 into CaCO3 is calculated with the following formula (2):
where it is assumed that the composition consists in two compounds CaCO3 and Ca(OH)2. The Ca(OH)2 content is directly derivable from the CaCO3 content, as follows Ca(OH)2(wt %)=100%−CaCO3 (wt %). TABLE 7 below shows the correspondence between the CO2 content and the CaCO3 content or the molar conversion of Ca(OH)2 into CaCO3 (also known as molar conversion of calcium hydroxide).
The results of the carbonation experiments are presented in
Samples 6 to 10 represent the present disclosure. Samples 1 to 5 and 11 are comparative examples. Samples 6 to 10 exhibit a molar conversion (of Ca(OH)2 into CaCO3) above about 70 mol % in the four tests A, B, C, D (when performed). This indicates that the hydroxide composition of the samples 6 to 10 is more robust in terms of molar conversion compared to the other hydrated lime samples when subjected to different weather conditions. To achieve such a molar conversion of at least 70% corresponding to a CO2 content of 33%, the composition has a partial pore volume equal to or higher than 0.09 cm3/g, in particular higher than 0.1 cm3/g, said partial pore volume being calculated according to the BJH method for a range of pores having a diameter between 20 and 200 Å in accordance with standard DIN 66134 (February 1998 version). Preferably, the difference between a total pore volume being calculated according to the BJH method for a range of pores having a diameter of between 20 and 1000 Å in accordance with standard DIN 66134 (February 1998 version) and said partial pore volume is equal to or higher than 0.06 cm3/g, preferably higher than 0.08 cm3/g. This element relates to a second aspect of the present disclosure also covered by the samples 6 to 10.
By BJH 20-100, BJH 20-200, BJH 20-1000 is meant the pore volume being calculated according to the BJH method for a range of pores having a diameter of between 20 and 100 Å, 20 and 200 Å and 20 and 1000 Å respectively in accordance with standard DIN 66134 (February 1998 version)
Additional aspects and features of the disclosure are presented below, without limitation, as a series of enumerated clauses.
A1. A process for direct capture of carbon dioxide in air comprising the following steps:
A2. The process according to Clause A1, further comprising mixing a calcium hydroxide-based powder composition with water and optionally a first additive or slaking quicklime, possibly partly hydrated, optionally in presence of a second additive in order to obtain a composition with a water content above 35% by weight of said composition, and optionally at most 85% by weight of said composition, in particular said composition being a malleable or flowable composition, such as a putty lime or a milk of lime.
A3. The process according to Clause A1 or A2, the step of providing the calcium hydroxide-based composition comprises providing the malleable or flowable composition such as a putty lime or a milk of lime, preferably said composition having a water content above 35% by weight of said composition, and optionally at most 85% by weight of said composition.
A4. The process according to Clause A2 or A3, further comprising shaping the malleable or flowable composition into shaped bodies (4), in particular 3D printings or extrudate, thereby forming the calcium hydroxide-based composition, preferably forming ridges on the shaped bodies, notably curing said shaped bodies with CO2 preferably said shaped bodies having at least one dimension greater than 3 mm.
A5. The process according to Clause A4, prior to the shaping of the shaped bodies (4), mixing the malleable or flowable composition with at least one element selected from the group comprising structural elements, such as woven or non-woven fibers, at least one additive, water, or any combination thereof, preferably the at least one additive being selected from the group comprising shaping additive, pore-forming agent, compressive strength enhancer such as cementitious material, additives to increase particle size such as gypsum and air entraining agent;
A6. The process according to Clause A1, further comprising shaping a calcium hydroxide-based powder composition into shaped bodies (4), in particular pellets, granules, extrudates, 3D printings or compacts such as tablets or briquettes, thereby forming the calcium hydroxide-based composition, preferably forming ridges on the shaped bodies, notably curing said shaped bodies with CO2, preferably said shaped bodies having at least one dimension greater than 3 mm.
A7. The process according to Clause A6, further comprising mixing a calcium hydroxide powder with at least one element selected from the group comprising structural elements such as woven or non-woven fibers, at least one additive, water, or any combination thereof, thereby forming the calcium hydroxide-based powder composition, preferably the at least one additive being selected from the group comprising shaping additive, pore-forming agent, com-pressive strength enhancer such as cementitious material, additives to in-crease particle size such as gypsum and air entraining agent.
A8. The process according to any of Clauses A1, A4 to A7, wherein the supply of the calcium hydroxide-based composition comprises the supply of the shaped bodies (4), in particular pellets, granules, extrudates, 3D printings or compacts such as tablets or briquettes, preferably said shaped bodies having at least one dimension greater than 3 mm.
A9. The process according to the Clause A1 wherein the supply of the calcium hydroxide-based composition comprises the supply of a calcium hydroxide-based composition with water lower than or equal to 35% by weight of said composition, preferably at most 20% by weight, more preferably at most 15% by weight of said composition, and/or at least 5% by weight, preferably at least 10% by weight of said composition, preferably said composition being in the form of powder.
A10. The process according to any of the previous Clauses, wherein the collection of the calcium carbonate-based composition takes place when said com-position reaches a CO2 content of at least 31%, preferably at least 33%, in particular at least 37% by weight on a dry basis.
A11. The process according to any of the preceding Clauses, further comprising a step of providing a support (11, 12, 13, 14, 30) for the calcium hydroxide-based composition, said support being stationary or in motion relative to a reference frame.
A12. The process according to Clause A8 in combination with any of Clauses 10 to 11, wherein the support is selected from the group comprising trommel, plate, such as corrugated plate, bucket, pile, shelf (14), tray, filter media, cartridge, grate, tile, wall, brick, carbonated product, net, ground, basket (14) and gabion (12).
A13. The process according to Clause A9 in combination with any of Clauses A10 to
A11, preferably further comprising applying said composition on a support to form a layer, in particular forming ridges on said layer, preferably the support being selected from the group comprising trommel, plate, such as corrugated plate, bucket, pile, shelf (14) tray, filter media (11), such as clothes or bags in a bag filter, cartridge, grate, tile, wall, brick, carbonated product ground and net.
A14. The process according to Clause A3 in combination with any of Clauses A10 to A11, preferably further comprising applying said composition on a support to form a layer, in particular forming ridges on said layer, preferably the support being selected from the group comprising plate, such as corrugated plate, bucket, pile, shelf (14), tray, filter media, such as clothes or bags in a bag filter, cartridge, grate, tile, wall, brick, bead (30) carbonated product, ground and net.
A15. The process according to any of Clauses A8 to A9 in combination with any of Clauses 10 to 11, further comprising the step of contacting the calcium hydroxide-based composition with air in a packed bed such as a fixed bed or a moving bed or in a fluidized bed such as a bubbling bed, a spouted bed, a circulating fluidized bed or an entrained bed.
A16. The process according to Clause A9 in combination with any of Clauses A10 to A11, further comprising flowing air through a filter media, such as clothes or bags in a bag filter, comprising the calcium hydroxide-based composition.
A17. The process according to any of the preceding Clauses, wherein the step of contacting the calcium hydroxide-based composition with said air further comprises comprising adjusting (20, 21, 26) at least one of:
A18. The process according to the preceding Clause, wherein further providing an air flow inlet arranged upstream from the calcium hydroxide-based composition and/or an air flow outlet arranged downstream from the calcium hydroxide-based composition.
A19. The process according to any of the Clauses A17 to A18, wherein the step of adjusting comprises adjusting as a function of at least one of:
A20. The process according to any of the preceding Clauses, wherein, in the step of contacting said composition with said air, the calcium hydroxide-based composition is exposed to air having temperatures falling in the range from 2° C. to 50° C., preferably in the range from 15° C. to 50° C. and/or relative humidity levels falling in the range from 10% to 95%, more preferably in the range from 10% to 80%, preferably the range from 10% to 50% or 40% to 80%.
A21. The process according to any of the preceding Clauses, further comprising conditioning the collected calcium carbonate-based composition prior to the step of extracting at least some CO2 from at least some of the collected calcium carbonate-based composition, preferably the step of conditioning comprising at least one of drying, grinding, milling, classifying, dehydroxylating or purifying the collected calcium carbonate-based composition, or any combination thereof, in particular the step of purifying comprising separating at least some of the un-reacted calcium hydroxide from the collected calcium carbonate-based composition, for instance via at least one of the following purification processes: air classification, leaching, pealing or floatation, or any combination thereof.
A22. The process according to any of the preceding Clauses, further comprising capturing at least a part of the CO2 formed during the step of extracting at least some CO2 from at least some of the collected calcium carbonate-based composition for subsequent sequestration and/or use.
B1. A calcium hydroxide-based composition characterized by:
C1. A calcium hydroxide-based composition characterized by:
C2. The calcium hydroxide-based composition according to Clause C1, wherein the calcium hydroxide-based composition is a flowable or malleable composition.
C3. A calcium hydroxide-based composition according to Clause C1 or C2, wherein said composition is a milk of lime or putty lime.
C4. The composition according to any of Clauses B1 or C1 to C3, wherein said composition reaches CO2 content of at least 31% by weight, preferably at least 33% by weight, more preferably at least 37% by weight, in particular at least 41% by weight on a dry basis when carbonated under a test where four samples, namely a first, second, third and fourth sample of said composition are in con-tact with four predefined CO2 enriched air compositions adapted to simulate an accelerated carbonatation in a weathering chamber, wherein each sample prior to the accelerated carbonatation is dried to reach a water content less than 1% by weight, said the CO2 content being the lowest of the four CO2 contents measured under the following conditions:
D1. A calcium hydroxide-based composition characterized by:
D2. The composition according to Clause D1, wherein said composition reaches a CO2 content of at least 31% by weight, preferably at least 33% by weight, more preferably at least 37% by weight, in particular at least 41% by weight on a dry basis when carbonated under a test where four samples, namely a first, second, third and fourth sample of said composition are in contact with four predefined CO2 enriched air compositions adapted to simulate an accelerated carbonatation in a weathering chamber, wherein each sample prior to the accelerated carbonatation is milled to an average particle diameter less than 250 μm, said the CO2 content being the lowest of the four CO2 contents measured under the following conditions:
D3. The composition according to any of Clauses D1 to D2, having a water content lower than or equal to 35% by weight of said composition, in particular of at least 5% by weight, preferably at least 10% by weight, and/or at most 20% by weight, preferably at most 15% by weight
D4. The composition according to any of Clauses B1, C1 to C4, or D1 to D3, having a weight fraction of Ca(OH)2 of at least 80%, preferably at least 90% on a dry basis.
E1. A calcium hydroxide-based powder composition, said composition having the following features:
E2. The composition according to the preceding clause, having a water content lower than or equal to 35% by weight of said composition, in particular of at least 5% by weight, preferably at least 10% by weight, and/or at most 20% by weight, preferably at most 15% by weight.
E3. The composition according to any of Clauses E1 to E3, wherein particle diameter average of the calcium hydroxide-based powder composition is less than 100 μm, preferably less than 10 μm.
By “apparent density”, is meant the mass of a shaped body divided by its apparent (envelope) volume, i.e. the volume calculated from the outer dimensions of the shaped body. The shaped body density takes into account the volume of solid material of the shaped body and the volume of the closed and open pores of the particles forming the shape body as well as the voids intraparticle void(s) between the particulates of the shaped body. The apparent density is measured with a mercury picnometer. The apparent density by means of mercury picnometry is measured on 0.3 g of the shaped body or a fragment thereof according to the following procedure (source: catalogue of PMI-Porous Material Inc., and ‘Improved mercury picnometry for measuring accurate volumes of solid materials’, by S Yamagishi and Y Takahashi, published on IOPScience website):
In case the shaped body weighs more than 0.3 g, it is fractioned and one fragment thereof weighting 0.3 g serves for the test. The measurement is repeated with five shaped bodies. It should be stressed that Norm DIN 66134 (February 1998 version) is intended for the measurement of the pore volumes of particulates where a milling step is necessary to transform the composition (e.g. shaped body) into powder. To the contrary, a milling step is not performed before the mercury picnometry tests in order to preserve the intraparticle voids within the shaped bodies. These voids strongly influence the apparent density of a shaped body.
While the present disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed present disclosure, from a study of the drawings, the disclosure and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.
The foregoing description details certain embodiments of the present disclosure. It will be appreciated, however, that no matter how detailed the foregoing appears in text, the present disclosure may be practiced in many ways, and is therefore not limited to the embodiments disclosed. It should be noted that the use of particular terminology when describing certain features or aspects of the present disclosure should not be taken to imply that the terminology is being re-defined herein to be restricted to include any specific characteristics of the features or aspects of the present disclosure with which that terminology is associated.
| Number | Date | Country | Kind |
|---|---|---|---|
| 23185150.2 | Jul 2023 | EP | regional |
