Method for obtaining carbon dioxide
The process converts calcium carbonate into calcium acetate, acetone, and acetic acid to obtain carbon dioxide efficiently, reducing energy costs and enabling a partial acetic acid cycle, with safety measures to prevent explosions.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- DR ING H C F PORSCHE AG
- Filing Date
- 2025-11-03
- Publication Date
- 2026-05-21
AI Technical Summary
Existing processes for obtaining carbon dioxide from calcium carbonate are energy-intensive and expensive due to the need for high temperatures in lime burning, which is a disadvantage of the lime cycle.
A process involving the conversion of calcium carbonate into calcium acetate using acetic acid, followed by conversion into acetone and calcium oxide, and then into acetic acid with hydrogen peroxide and a catalyst, allowing for a break in the lime cycle and enabling the reuse of acetic acid, with heat management and explosion prevention measures.
This process reduces energy consumption and costs by avoiding high-temperature lime burning, facilitates carbon dioxide collection and storage, and establishes a partial acetic acid cycle, while ensuring safety through controlled reactant concentrations.
Smart Images
Figure EP2025000046_21052026_PF_FP_ABST
Abstract
Description
[0001] Processes for obtaining carbon dioxide
[0002] The invention relates to a process for obtaining carbon dioxide from calcium carbonate.
[0003] Methods for extracting carbon dioxide from ambient air to reduce carbon dioxide levels in the air are called Direct Air Capture (DAC).
[0004] One way to bind carbon dioxide from the air is to utilize the lime cycle, or a part of it. In this process, calcium oxide (quicklime) is slaked by adding water. This exothermic reaction produces calcium hydroxide (slaked lime). Calcium hydroxide reacts with carbon dioxide from the ambient air, releasing water to form calcium carbonate; thus, the carbon dioxide atoms are bound within the calcium carbonate.
[0005] The next goal is to further use the calcium carbonate or to extract and collect the carbon dioxide from the calcium carbonate.
[0006] Calcium carbonate can be decomposed by lime burning, producing carbon dioxide and calcium oxide, thus closing the lime cycle. The carbon dioxide can, for example, be liquefied, and the calcium oxide can be reused in the DAC process. However, a disadvantage is that lime burning requires temperatures above 898 °C. This makes the process energy-intensive and expensive.
[0007] CN 20 182347 U shows a process from the field of adsorption of carbon dioxide and regeneration of coal-fired boilers.
[0008] CN 110294668 A discloses a method for the natural production of acetone using calcium carbonate.
[0009] GB 747819 A discloses a process for the production of acetone using calcium carbonate and acetic acid. DE 102011 088 122 A1 discloses a process for the simple and cost-effective extraction of an alkaline earth metal component and the production of a carbonate precipitate.
[0010] It is therefore an object of the invention to provide a new process for the conversion of calcium carbonate.
[0011] This problem is solved by the subject matter of claim 1.
[0012] A process for obtaining carbon dioxide from calcium carbonate involves the following steps:
[0013] A) By adding acetic acid, the calcium carbonate is converted into calcium acetate, producing water and carbon dioxide;
[0014] B) the calcium acetate is converted into acetone and calcium oxide by heating, producing carbon dioxide;
[0015] C) The acetone is converted into acetic acid as one of the products in a reaction process with the addition of hydrogen peroxide as one of the reactants and in the presence of a catalyst.
[0016] This allows for a break in the lime cycle and the replacement of lime burning. Furthermore, a (partial) cycle is possible with regard to acetic acid.
[0017] According to a preferred embodiment, heat energy is supplied to the calcium carbonate and the acetic acid in step A). This accelerates the reaction and increases the yield.
[0018] According to a preferred embodiment, the resulting carbon dioxide is collected in a container. This enables transport and / or further processing.
[0019] According to a preferred embodiment, the resulting carbon dioxide is liquefied in a cooling process. This allows the carbon dioxide to be stored in a space-saving manner. According to a preferred embodiment, the acetic acid produced by adding carbon monoxide is reused in step A). This enables a closed (partial) cycle with respect to the acetic acid.
[0020] According to a preferred embodiment, a Cu(ll) polymer catalyst is used in step C). Various possibilities for such catalysts are mentioned.
[0021] According to a preferred embodiment, the hydrogen peroxide is added in aqueous solution in step C). This is possible with the reactants, and the risk of explosion is reduced.
[0022] According to a preferred embodiment, the hydrogen peroxide in step C) has a volume fraction which is less than at least a first volume fraction from a first group consisting of:
[0023] - 0.050,
[0024] - 0.040,
[0025] - 0.030,
[0026] - 0.020, and
[0027] - 0.010.
[0028] These volume fraction limits reduce the risk of explosion.
[0029] According to a preferred embodiment, the acetone in step C) has a volume fraction which is less than at least a second volume fraction from a second group consisting of:
[0030] - 0.100,
[0031] - 0.080,
[0032] - 0.070,
[0033] - 0.060,
[0034] - 0.050, and
[0035] - 0.040.
[0036] These volume fraction limits reduce the risk of explosion.
[0037] According to a preferred embodiment, methyl acetate is formed as one of the products in step C) of the reaction process. According to a preferred embodiment, the hydrogen peroxide for step C) is produced by an anthraquinone process. This process enables the efficient production of hydrogen peroxide in the present method.
[0038] According to a preferred embodiment, the calcium oxide from step B) is converted to calcium hydroxide in step D) by adding water. This is a strongly exothermic reaction, and the heat can be used in other process steps.
[0039] According to a preferred embodiment, the heat generated in step D) is at least partially used to heat the calcium carbonate and the acetic acid in step A). This advantageously allows the generated heat energy to be used within the process.
[0040] According to a preferred embodiment, the calcium hydroxide produced in step D) is converted into calcium carbonate in step E) by adding carbon dioxide.
[0041] According to a preferred embodiment, the calcium carbonate produced in step E) is reused in step A). This closes the calcium cycle.
[0042] Further details and advantageous embodiments of the invention will become apparent from the exemplary embodiments described below and illustrated in the drawing, which are in no way to be understood as limiting the invention, as well as from the dependent claims. It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the present invention. The drawing shows:
[0043] Fig. 1 shows a process for producing carbon dioxide from calcium carbonate. The descriptions of the figures are sequential, and the features are usually described only once.
[0044] Fig. 1 shows a process for obtaining carbon dioxide from calcium carbonate with a step A), a step B) and a step C).
[0045] The process has the following steps:
[0046] A) By adding acetic acid, the calcium carbonate is converted into calcium acetate, producing water and carbon dioxide;
[0047] B) the calcium acetate is converted into acetone and calcium oxide by heating, producing carbon dioxide;
[0048] C) The acetone is converted into acetic acid as one of the products in a reaction process with the addition of hydrogen peroxide as one of the reactants and in the presence of a catalyst.
[0049] The procedure is described in detail below.
[0050] Calcium carbonate can be decomposed by lime burning, producing carbon dioxide and calcium oxide. However, a disadvantage is that lime burning requires temperatures above 898 °C. This makes the process energy-intensive and expensive.
[0051] As a possible alternative to lime burning and to obtain carbon dioxide (CO2), it is proposed to react calcium carbonate (CaCOs) with acetic acid (CH3COOH) to obtain carbon dioxide as a product.
[0052] The overall reaction is
[0053] 2 CH3COOH + CaCOs - Ca(CH3COO)2+ H2O + CO2
[0054] The reaction of two acetic acid molecules with calcium carbonate produces calcium acetate, water and carbon dioxide.
[0055] The carbon dioxide escapes as a gas and can be collected. Preferably, the carbon dioxide is collected in a container. Preferably, the collected carbon dioxide is liquefied, in particular by a cooling process.
[0056] In step B), the calcium acetate is converted into acetone (CsHeO) and calcium oxide (CaO) by heating, producing carbon dioxide.
[0057] Acetone (CsHeO) is converted to acetic acid in a reaction process involving the addition of hydrogen peroxide (H2O2) as one of the reactants and in the presence of a catalyst. Methyl acetate (C3H6O2) is formed as a further product.
[0058] In this reaction, in addition to the products acetic acid (CH3COOH) and methyl acetate (C3H6O2), other products such as methylglyoxal (CH3COCHO), formaldehyde (HCHO), carbon monoxide (CO), carbon dioxide (CO2), methanol (CH3OH) and formic acid (HCOOH) are formed.
[0059] A Cu(ll) polymer catalyst is preferably used as the catalyst in step C). Other catalysts can also lead to an increase in yield.
[0060] Preferably, the copper(II) coordination polymer catalyst carries the arylhydrazone of acetoacetanilide.
[0061] In the publication by Dr. Atash V. Gurbanov et al., Chemistry Europe, “Mechanochemical and Conventional Synthesis of Copper(ll) Coordination Polymers Bearing Arylhydrazone of Acetoacetanilide and Their Catalytic Activity in Conversion of Acetone to Acetic Acid”, https: / / doi.org / 10.1002 / slct.202001836, it is stated that such catalysts lead to a corresponding reaction at room temperature with a yield of 50%.
[0062] As an example of the catalyst's preparation, it is described that the starting material (ball-milled intermediate) was produced by treating a mixture of CuCh • 2 H₂O (1.00 mmol, 170 mg) and H₃L (1.00 mmol, 325 mg) in a Retsch PM100 planetary ball mill for 1 h at 450 rpm, reversing the direction of rotation every 5 min. Recrystallization of this precursor in acetone, MeOH (methanol), or DMF (dimethylformamide) leads to the crystalline compounds 1, 2, and 3 mentioned in the publication, which can serve as catalysts, namely...
[0063] [Cu( 2-HL)] n -n(CH3)2C=O (1),
[0064] [Cu( / Ji-HL)(CH3OH)] n (2) and
[0065] [Cu( i-HL)(H2O)] n (3)
[0066] A mixture of acetone and hydrogen peroxide can be explosive at high concentrations.
[0067] The hydrogen peroxide is preferably added in aqueous solution in step C). This reduces the risk of explosion.
[0068] The hydrogen peroxide preferably has a volume fraction in step C) which is less than at least a first volume fraction from a first group consisting of:
[0069] - 0.050,
[0070] - 0.040,
[0071] - 0.030,
[0072] - 0.020, and
[0073] - 0.010.
[0074] This reduces the risk of an explosion.
[0075] In step C), the acetone preferably has a volume fraction which is less than at least a second volume fraction from a second group consisting of:
[0076] - 0.100,
[0077] - 0.080,
[0078] - 0.070,
[0079] - 0.060,
[0080] - 0.050, and
[0081] - 0.040. This reduces the risk of explosion, especially at a corresponding concentration of hydrogen peroxide according to the first group.
[0082] The yield of acetic acid in step C) increases with higher volume fractions of hydrogen peroxide and acetone. Therefore, the aim is to use the highest possible volume fraction of these substances while ensuring process reliability.
[0083] Preferably, the produced acetic acid is reused in step A) to convert calcium carbonate to calcium acetate. Thus, at least part of the acetic acid is recycled.
[0084] The hydrogen peroxide for step C) is preferably produced by an anthraquinone process. Anthraquinone acts as a catalytic agent in this process.
[0085] Naturally, various variations and modifications are possible within the scope of the invention.
[0086] In all the reactions mentioned, further reactants can be used, and thus further products can be formed.
Claims
Patent claims 1. A process for obtaining carbon dioxide from calcium carbonate, comprising the following steps: A) By adding acetic acid, the calcium carbonate is converted into calcium acetate, producing water and carbon dioxide; B) the calcium acetate is converted into acetone and calcium oxide by heating, producing carbon dioxide; C) The acetone is converted into acetic acid as one of the products in a reaction process with the addition of hydrogen peroxide as one of the reactants and in the presence of a catalyst.
2. The method according to claim 1, wherein the resulting carbon dioxide is collected in a container.
3. Method according to claim 1 or 2, wherein the resulting carbon dioxide is liquefied in a cooling process.
4. A method according to any of the preceding claims, wherein the acetic acid produced in step C) is used again in step A).
5. Method according to one of the preceding claims, wherein in step C) Cu(ll) polymer catalyst is used as catalyst.
6. Method according to any of the preceding claims, wherein the hydrogen peroxide is added in aqueous solution in step C).
7. A method according to any of the preceding claims, wherein the hydrogen peroxide in step C) has a volume fraction which is less than at least a first volume fraction from a first group consisting of: - 0.050, - 0.040, - 0.030, - 0.020, and - 0.
010.
8. Method according to any of the preceding claims, wherein the acetone in step C) has a volume fraction which is less than at least a second volume fraction from a second group consisting of: - 0.100, - 0.080, - 0.070, - 0.060, - 0.050, and - 0.
040.
9. Method according to any one of the preceding claims, in which methyl acetate is formed as one of the products in step C) of the reaction process.
10. Method according to any of the preceding claims, wherein the hydrogen peroxide for step C) is produced by an anthraquinone process.
11. Method according to one of the preceding claims, wherein the calcium oxide from step B) is converted into calcium hydroxide in step D) by adding water.
12. Method according to claim 11, in which the heat generated in step D) is at least partially used to heat the calcium carbonate and the acetic acid in step A).
13. Method according to claim 11 or 12, wherein the calcium hydroxide produced in step D) is converted into calcium carbonate in step E) by adding carbon dioxide.
14. Method according to claim 13, in which the calcium carbonate produced in step E) is used again in step A).
15. Method according to one of the preceding claims, wherein heat energy is supplied to the calcium carbonate and the acetic acid in step A).