A method to capture and utilize CO2 and an installation for capturing and utilizing CO2

Abstract

The invention relates to a cyclic method for capturing and utilizing CO.sub.2 contained in a gas stream. The method uses three different materials, a first solid material, a second solid material and a CO.sub.2 sorbent material.

In a first step a first gas stream comprising CO.sub.2 and at least one reductant is brought in contact with the three materials, resulting in an outlet stream comprising water. In a second step, the captured CO.sub.2 from the first step is released and converted to CO to produce a CO rich outlet stream. The invention further relates to an installation for capturing and utilizing CO.sub.2.

Claims

1. Cyclic method of capturing and utilizing CO.sub.2 contained in a gas stream, said method comprising a first and a second step wherein said first step comprises introducing a first gas stream to contact a first solid material, a second solid material and a CO.sub.2 sorbent material, said first gas stream comprising CO.sub.2 and at least one reductant, with the process conditions of said first step comprising a temperature ranging between 573 K and 1473 K and a pressure ranging between 0.1 and 100 bar; said second step comprises introducing a second gas stream to contact said CO.sub.2 sorbent material, said second solid material and said first solid material, said second gas stream comprising at least one oxidant, with the process conditions of said second step comprising a temperature ranging between 573 K and 1473 K and a pressure ranging between 0.01 and 10 bar; wherein said first solid material has a first thermodynamic equilibrium oxygen partial pressure p1.sub.O.sub.2.sub.,eq and said second solid material having a second thermodynamic equilibrium oxygen partial pressure p2.sub.O.sub.2.sub.,eq with said second thermodynamic equilibrium oxygen partial pressure p2.sub.O.sub.2.sub.,eq being larger than said first thermodynamic equilibrium oxygen partial pressure p1.sub.O.sub.2.sub.,eq at the process conditions of said first step and at the process conditions of said second step, wherein said first solid material oxidizes said at least one reductant at least partially in said first step and under the process conditions of said first step and said first solid material is oxidized by CO.sub.2 in said second step and under the process conditions of said second step and wherein said second solid material oxidizes said at least one reductant in said first step and under the process conditions of said first step and said second solid material is not oxidized by CO.sub.2 and not oxidized by H.sub.2O in said second step and under the process conditions of said second step and wherein said CO.sub.2 sorbent material is capturing CO.sub.2 in said first step under the process conditions of said first step and said CO.sub.2 sorbent material is releasing CO.sub.2, preferably the CO.sub.2 captured in said first step, in said second step and under the process conditions of said second step.

2. The method according to claim 1, wherein said second thermodynamic equilibrium oxygen partial pressure p2.sub.O.sub.2.sub.,eq is at least one order of magnitude larger than said first thermodynamic equilibrium oxygen partial pressure p1.sub.O.sub.2.sub.,eq at the process conditions of said first step and at the process conditions of said second step.

3. The method according to claim 1, wherein said first step and said second step are repeated periodically and/or wherein said method comprises in said first and/or in said second step one or more intermediate steps before or after contacting said first solid material and/or before or after contacting said second solid material and/or before or after contacting said CO.sub.2 sorbent material.

4. The method according to claim 1, wherein said second solid material is oxidized in said second step and under the process conditions of said second step.

5. The method according to claim 1, wherein said first solid material is reversibly reduced in said first step and under the process conditions of said first step.

6. The method according to claim 1, wherein said first solid material comprises a material comprising iron, cerium, zirconium, iridium, tungsten, molybdenum, lanthanum, strontium, samarium, neodymium, manganese or combinations thereof.

7. The method according to claim 1, wherein said second solid material comprises a material comprising manganese, nickel, copper, cobalt, iron, strontium, magnesium, titanium, calcium, lanthanum or combinations thereof.

8. The method according to claim 1, wherein said CO.sub.2 sorbent material comprises an alkali metal or alkaline earth metal and wherein said CO.sub.2 sorbent material is optionally promoted with a doping element selected from the group selected from the group consisting of aluminium, cerium, zirconium, magnesium or combinations thereof.

9. The method according to claim 1, wherein said at least one reductant comprises an organic compound, an alcohol, CO, H.sub.2 or a mixture thereof.

10. The method according to claim 1, wherein said at least one oxidant in said second gas stream comprises oxygen or nitrogen oxides.

11. The method according to claim 1, wherein said first gas stream is subsequently contacting said first solid material, said second solid material and said CO.sub.2 sorbent material in said first step and said second gas stream is subsequently contacting said CO.sub.2 sorbent material, said second solid material and said first solid material in said second step.

12. An installation for capturing and utilizing CO.sub.2, said installation comprising at least one inlet for introducing a first gas stream comprising CO.sub.2 and at least one reductant, at least one inlet for introducing a second gas stream comprising at least one oxidant, at least one outlet for providing a first outlet stream, at least one outlet for providing a second outlet stream, said installation further comprising a first flow path extending from said at least one inlet for introducing said first gas stream to said at least one outlet for providing said first outlet stream and allowing said first gas stream to contact a first solid material, a second solid material and a CO.sub.2 sorbent material and a second flow path extending from said at least one inlet for introducing said second gas stream to said at least one outlet for providing said second outlet stream outlet and allowing said second gas stream flow to contact said CO.sub.2 sorbent material, said second solid material and said first solid material, wherein said first solid material has a first thermodynamic equilibrium oxygen partial pressure p1.sub.O.sub.2.sub.,eq and said second solid material has a second thermodynamic equilibrium oxygen partial pressure p2.sub.O.sub.2.sub.,eq with said second thermodynamic equilibrium oxygen partial pressure p2.sub.O.sub.2.sub.,eq being larger than said first thermodynamic equilibrium oxygen partial pressure p1.sub.O.sub.2.sub.,eq at a temperature ranging between 573 K and 1473 K and a pressure ranging between 0.01 bar and 100 bar, wherein said first solid material is in said first flow path and under the process conditions of said first flow path at least partially oxidising said at least one reductant and said first solid material is oxidized by CO.sub.2 in said second flow path and under the process conditions of said second flow path, and wherein said second solid material is in said first flow path and under the process conditions of said first flow path oxidising said at least one reductant and said second solid material is neither oxidized by CO.sub.2 nor by H.sub.2O in said second flow path and under the process conditions of said second flow path.

13. The installation according to claim 11, wherein said first flow path and said second flow path are provided in a single reactor or wherein said first flow path is provided in a first reactor and said second flow path is provided in a second reactor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0087] The present invention will be discussed in more detail below, with reference to the attached drawings, in which:

[0088] FIG. 1 schematically shows the reactions of a first method of capturing and utilizing CO.sub.2 in a method according to the present invention;

[0089] FIGS. 2-9 show a schematic illustration of different embodiments of a reactor for capturing and utilizing CO.sub.2 according to the present invention;

[0090] FIG. 10 schematically shows the reactions of an alternative method of capturing and utilizing CO.sub.2 in a method according to the present invention;

[0091] FIG. 11 shows a schematic illustration of an alternative reactor for capturing and utilizing CO.sub.2 according to the present invention.

DESCRIPTION OF EMBODIMENTS

[0092] The present invention will be described with respect to particular embodiments and with reference to certain drawings, but the invention is not limited thereto but only by the claims. The drawings are only schematic and are non-limiting. The size of some of the elements in the drawings may be exaggerated and not drawn on scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

[0093] When referring to the endpoints of a range, the endpoints values of the range are included.

[0094] When describing the invention, the terms used are construed in accordance with the following definitions, unless indicated otherwise.

[0095] The term ‘and/or’ when listing two or more items, means that any one of the listed items can by employed by itself or that any combination of two or more of the listed items can be employed.

[0096] The terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0097] For the purpose of the present application, a chemical looping process is defined as a chemical reaction with solid intermediates that is split into multiple sub-reactions and either executed in separate reactors or in alternating manner in a single reactor.

[0098] Oxygen storage material is defined as a solid intermediate which can exchange oxygen during a chemical looping process.

[0099] A CO.sub.2 sorbent is defined as a material, often containing (earth) alkali metal oxides, which can periodically capture and release CO.sub.2 by formation and decomposition of metal carbonate, for example (earth) alkali metal carbonate.

[0100] A catalyst is defined as a substance or material, which through repeated cycles of elementary steps, accelerates the conversion of reagents into products. Catalysts may comprise homogeneous catalysts, which are in the same phase with the reagents (for example acids and bases, metal complexes, etc.), and heterogeneous catalysts, which are separated from the reactants by an interface (for example metals, metal oxide, etc.).

[0101] Syngas is defined as a (variable) composition mixture of hydrogen and carbon monoxide.

[0102] FIG. 1 schematically shows the reactions of a method for capturing and utilizing CO.sub.2 according to the present invention. The dashed-lines in the lower half-circles indicate the reactions in the first step, the lines in the upper half-circles indicate the reactions in the second step.

[0103] FIG. 2 shows an example of an installation for capturing and utilizing CO.sub.2 based on the reactions shown in FIG. 1. The installation shown in FIG. 2 comprises a fixed bed reactor. It should be clear that other types of reactors such as fluidized bed reactors and moving bed reactors can be considered as well.

[0104] The installation 1 comprises at least three different materials, preferably at least three different metal oxides. The installation 1 comprises for example a first solid material A comprising Me.sub.1O.sub.x/Me.sub.1, a second solid material B comprising Me.sub.2O.sub.y/Me.sub.2 and a CO.sub.2 sorbent material C comprising Me.sub.3/Me.sub.3CO.sub.2. The method comprises preferably two sequential steps, i.e. step 1 and step 2.

[0105] The first solid material A comprises for example Fe.sub.xO.sub.y; the second solid material B comprises for example MnO.sub.x and the CO.sub.2 sorbent material C comprises for example CaO, optionally promoted with Al.sub.2O.sub.3, CeO.sub.2, MgO, or, ZrO.sub.2.

[0106] In the first step fuel and CO.sub.2 is introduced as first gas stream 2. The first gas stream 2 may further comprise N.sub.2 and/or impurities. The first gas stream 2 comprises for example an industrial gas stream comprising CO.sub.2. The first gas stream 2 may also comprise a biogas. In the second step air is introduced as second gas stream 3.

[0107] The reactor 1 shown in FIG. 2 schematically shows a fixed bed reactor 1, having different zones 4, 5, 6. The first zone 4 comprises a first solid material A (for example Fe.sub.xO.sub.y) and a CO.sub.2 sorbent material C (for example CaO, optionally promoted with Al.sub.2O.sub.3, CeO.sub.2, MgO, or, ZrO.sub.2); the second zone 5 comprises the second solid material B (for example MnO.sub.x) and the third zone comprises for example a CO.sub.2 sorbent material C (for example CaO, optionally promoted with Al.sub.2O.sub.3, CeO.sub.2, MgO, or, ZrO.sub.2). The first gas stream 2 is introduced to contact first the first zone 4 and subsequently the second zone 5 and the third zone 6. The second gas stream is introduced to contact first the third zone 6 and subsequently the second zone 5 and the first zone 4. The reactor 1 is provided with a first outlet 8 and a second outlet 9.

[0108] The following reactions occur in the first step and in the second step, in the different zones:

TABLE-US-00001 TABLE 1 1.sup.st step 2.sup.nd step 1.sup.st zone C.sub.mH.sub.nO.sub.p (fuel) + Me.sub.1O.sub.x ⇄ Me.sub.1O.sub.x − m + p + n/2 H.sub.2 + Me.sub.1O.sub.x − 1 + CO.sub.2 ⇄ Me.sub.1O.sub.x + CO (4) m CO Me.sub.1O.sub.x − m + p + (m − p) CO.sub.2 ⇄ Me.sub.1O.sub.x + (m − p) CO Me.sub.1O.sub.x + H.sub.2 ⇄ Me.sub.1O.sub.x + H.sub.2O Me.sub.3CO.sub.2 ⇄ Me.sub.3 + CO.sub.2 Me.sub.1O.sub.x + CO ⇄ Me.sub.1O.sub.x + CO.sub.2 Me.sub.3 + CO.sub.2 ⇄ Me.sub.3CO.sub.2 2.sup.nd zone C.sub.mH.sub.nO.sub.p (fuel) + Me.sub.2O.sub.y .fwdarw. Me.sub.2O.sub.y − 2m − 0.5n + p + (m + 0.25n − 0.5p) O.sub.2 + Me.sub.2O.sub.y − 2m − 0.5n + p .fwdarw. (5) n/2 H.sub.2O + m CO.sub.2 Me.sub.2O.sub.y 3.sup.th zone Me.sub.3 + CO.sub.2 ⇄ Me.sub.3CO.sub.2 Me.sub.3CO.sub.2 ⇄ Me.sub.3 + CO.sub.2 (6)

[0109] FIG. 3 shows an alternative installation 1 of a fixed bed reactor comprising a first zone 10 and a second zone 11. The first zone 10 comprises a first solid material A and a CO.sub.2 sorbent material C; the second zone 11 comprises a second solid material B and a CO.sub.2 sorbent material C′. The CO.sub.2 sorbent material C′ of the second zone 11 can be the same as the CO.sub.2 sorbent material C of the first zone 10. Alternatively, the second zone 11 comprises another CO.sub.2 sorbent material C′ than the first zone 10. The first gas stream 2 is introduced to contact first the first zone 10 and subsequently the second zone 11. The second gas stream 3 is introduced to contact first the second zone 11 and subsequently the first zone 10. The reactor 1 is provided with a first outlet 8 and a second outlet 9.

[0110] FIG. 4 shows an alternative installation of a fixed bed reactor 1 comprising a first zone 12 and a second zone 13. The first zone 12 comprises a first solid material A and a CO.sub.2 sorbent material C; the second zone 13 comprises a second solid material B. The first gas stream 2 is introduced to contact first the first zone 12 and subsequently the second zone 13. The second gas stream 3 is introduced to contact first the second zone 13 and subsequently the first zone 12. The reactor 1 is provided with a first outlet 8 and a second outlet 9.

[0111] FIG. 5 shows a further embodiment of a reactor 1 according to the present invention. The reactor comprises a first zone 14 and a second zone 15. The first zone 14 comprises a second solid material B. The second zone 15 comprises a first solid material A and a CO.sub.2 sorbent material C. Both the first gas stream 2 and the second gas stream 3 are introduced to contact first the first zone 14 and subsequently the second zone 15. The reactor 1 is provided with a first outlet 8 and a second outlet 9.

[0112] FIG. 6 shows a further embodiment of an installation of a reactor according to the present invention comprising one zone 16 comprising a first solid material A, a second solid material B and a CO.sub.2 sorbent material C. The first gas stream 2 and the second gas stream 3 are introduced in the same direction. The reactor 1 is provided with a first outlet 8 and a second outlet 9.

[0113] The reactor of FIG. 7 corresponds with the reactor of FIG. 6 comprising one zone 17 comprising a first solid material A, a second solid material B and a CO.sub.2 sorbent material C, the first gas stream 2 and the second gas stream 3 are however introduced in opposite directions.

[0114] FIG. 8 shows a further embodiment of a reactor 1 according to the present invention. The reactor comprises a first zone 18 and a second zone 19. The first zone 18 comprises a first solid material A and a CO.sub.2 sorbent material C. The second zone 19 comprises a second solid material B and a CO.sub.2 sorbent material C. Both the first gas stream 2 and the second as stream are introduced to contact first the second zone 19 and subsequently the first zone 18. The reactor 1 is provided with a first outlet 8 and a second outlet 9.

[0115] FIG. 9 shows a further embodiment of a reactor 1 according to the present invention. The reactor comprises a first zone 20, a second zone 21 and a third zone 22. The first zone 20 comprises a second solid material B. The second zone 21 comprises a CO.sub.2 sorbent material C. The third zone 22 comprises a first solid material A. The first gas stream 2 is introduced to contact first the first zone 20 and subsequently the second zone 21 and the third zone 22. The second gas stream 3 is introduced to contact first the first zone 20 and subsequently the second zone 21 and the third zone 22. The reactor 1 is provided with a first outlet 8 and a second outlet 9.

[0116] FIG. 10 schematically shows the reactions of a second method to capture and utilize CO.sub.2 according to the present invention similar to FIG. 1 but comprising a reformer catalyst. FIG. 11 shows an example of an installation for capturing and utilizing CO.sub.2 based on the reactions shown in FIG. 10, including a reforming catalyst.

[0117] The reforming catalyst can, for example, be a Ni-, Re- or Cu-based catalyst or a noble metal based catalyst such as a Pt- or Rh-based catalyst.

[0118] FIG. 11 shows an embodiment of a reactor 1 further comprising a reformer catalyst 23. The reactor comprises a first zone 24 and a second zone 24. The first zone 24 comprises a first solid material A and a CO.sub.2 sorbent material C. The second zone 25 comprises a second solid material B and a CO.sub.2 sorbent material C. The first gas stream 2 is introduced to contact first the reformer catalyst 23 and subsequently the first zone 24 and the second zone 25. The second gas stream 3 is introduced to contact first the second zone 25 and subsequently the first zone 24. The reactor 1 is provided with a first outlet 8 and a second outlet 9.

Experimental Results

[0119] A proof of concept experiment involved testing the three materials in a fixed bed reactor enclosed in an electrically heated furnace. The reactor made from quartz glass had an internal diameter of about 7.5 mm. Mass flow controllers by Bronkhorst (EL-Flow) were used for sending known quantities of reactant and/or inert gases into the reactor. For the analysis of the output gas streams from the reactor, a mass spectrometer was used with Ar as an internal standard gas for quantification purposes.

[0120] About 1.4 g of a conventional manganese-based oxygen carrier was used as solid material (second solid material) in a first zone of the reactor. A second zone of the reactor comprises a mixture of 1 g of a conventional calcium oxide based CO.sub.2 sorbent and about 1 g of a conventional iron-based oxygen carrier. The first gas stream was introduced in the reactor to follow a flow path wherein first the first zone is contacted and subsequently the second zone is contacted. The second gas stream was introduced in the reactor to follow the same flow path of the first gas stream, i.e. to first contact the first zone and subsequently the second zone. This experiment's configuration applied the embodiment displayed in FIG. 5.

[0121] The first gas stream comprises a mixture of CO, H.sub.2, CO.sub.2 and an inert mixture of Ar and He and resembles the composition of a gas from a steel mill with N.sub.2 replaced by an inert mixture of Ar and He. The molar ratio between the gases, H.sub.2, CO, CO.sub.2, Ar, and He was approximately 1:5:5:8:1. The second gas stream comprises a mixture of O.sub.2 and Ar with a molar ratio of approximately 1:19. A fast switching pneumatic valve was used to switch from the first gas stream to the second gas stream. Throughout the experiment, the flow of the input gases (the first and the second gas stream) fed into the reactor was kept constant at about 6.1 mmol/min.

[0122] With the use of three-zone external heating of the fixed bed reactor, a uniform temperature of about 1023 K (750° C.) was maintained. A type K thermocouple was placed inside zone 2 for measuring the temperature of the bed. The pressure was kept constant between 1.1 to 1.3 bar, very close to ambient pressure, and maintained throughout the experiment.

[0123] In a typical cycle, the first step (reduction) and the second step (oxidation) of the cyclic method were prolonged to about 20 seconds. During the first step (reduction), on an H.sub.2O-free basis the first outlet had the measured output molar ratio of H.sub.2, CO, CO.sub.2, Ar, and He was approximately 1:0.3:1:29:5 over its duration (compared to 1:5:5:8:1 in the feed gas). The enrichment of the inert content in the gas indicated high utilisation of the chemical energy of the incoming feed gas and CO.sub.2 capture from the incoming feed gas. The presence of unreacted H.sub.2 and CO represents an opportunity to further optimise the results (for example, by shortening the cycle times).

[0124] During the second step (oxidation), the second outlet stream had the following molar composition on an H.sub.2O-free basis: 3% CO, 5% CO.sub.2, 91% Ar, and less than 1% Hz. The presence of Hz during oxidation when O.sub.2 and Ar were fed may be indicative of clogged water in the lines being purged into the reactor by O.sub.2/Ar flow and/or the non-ideal response of the switch from first inlet stream to the second inlet stream. Although the use of Ar or any other inert is beneficial in the second step, its use may be minimised or almost eliminated by generating heat by the use of a stronger oxidising mixture like air. The presence of CO in the experimental results despite an input of O.sub.2 at about 1023 K (750° C.) proves that a CO-rich stream is feasible from this approach. Further optimisation of the experiment could possibly lead to absence of Hz, further minimisation of Ar used in the second outlet stream, and a higher ratio of CO:CO.sub.2 (current experimental results indicate a ratio of 0.6).

[0125] The thermodynamic equilibrium partial oxygen pressure of the solid materials used in the above mentioned proof of concept experiment manganese-based oxygen (MnO.sub.x) carrier ((MnO.sub.x) as second solid material) and iron-based oxygen carrier (FeO.sub.x) as first solid material are calculated below.

[0126] The total pressure in the experiment was close to the ambient pressure. At the reaction temperature of 1023 K, reactions (7) to (10) should be considered.

6Mn.sub.2O.sub.3⇄4Mn.sub.3O.sub.4+O.sub.2  (7)

2Mn.sub.3O.sub.4⇄6MnO+O.sub.2  (8)

2Fe.sub.3O.sub.4⇄6FeO+O.sub.2  (9)

2FeO⇄2Fe+O.sub.2  (10)

The thermodynamic calculations for estimating the thermodynamic equilibrium oxygen partial pressure p.sub.O.sub.2.sub.,eq.sub.1023 K of the different materials are presented in Table 2. From the values of p.sub.O.sub.2.sub.,eq.sub.1023 K presented in Table 2, it is clear that the second solid material (Mn.sub.2O.sub.3 and Mn.sub.3O.sub.4 among MnO.sub.x species) has a thermodynamic equilibrium oxygen partial pressure several orders of magnitude greater than that of the first solid material (Fe.sub.3O.sub.4 and FeO among FeO.sub.x species).

TABLE-US-00002 TABLE 2 Standard thermodynamic properties of solid components at 1023 K (reaction temperature) Reaction equation [00002]$\Delta H_{1023K}^0\left(\frac{J}{\mathrm{mol}}\right)$ [00003]${\Delta S}_{1023K}^0\left(\frac{J}{\mathrm{mol}.K}\right)$ [00004]$\Delta G_{1023K}^0\left(\frac{J}{\mathrm{mol}}\right)$ p.sub.o.sub.2,.sub.eq.sub.1023K(Pa)  (7) 217901 175 38815 1057  (8) 463106 233 294933   9 * 10.sup.−11  (9) 604374 217 381892 3.2 * 10.sup.−15 (10) 526444 128 395705 6.3 * 10.sup.−16