CYCLIC METHOD OF PRODUCING A HYDROGEN RICH STREAM AND/OR A CARBON MONOXIDE RICH STREAM

Abstract

The invention relates to a cyclic method of producing a hydrogen rich and/or a carbon monoxide rich stream using 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 steam and at least one reductant is brought in contact with the three materials resulting in a hydrogen rich outlet stream.

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 producing a hydrogen rich and/or carbon monoxide rich stream.

Claims

1. A cyclic method of producing a hydrogen rich stream and/or a carbon monoxide rich stream, said method comprises a first step and a second step, wherein said first step comprises introducing a first gas stream to contact a first solid material, a first CO.sub.2 sorbent material and a second solid material to provide a first outlet stream comprising said hydrogen rich stream, said first gas stream comprising steam 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 and; said second step comprising introducing a second gas stream to contact said first solid material, said first CO.sub.2 sorbent material and said second solid material to provide a second outlet stream comprising said carbon monoxide rich stream, 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 100 bar, wherein said first outlet stream and said second outlet stream are preferably separated from each other, 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 first thermodynamic equilibrium oxygen partial pressure p1.sub.O.sub.2.sub.,eq being larger than said second thermodynamic equilibrium oxygen partial pressure p2.sub.O.sub.2.sub.,eq at the process conditions of said first step and at the process conditions of said second step larger than said second thermodynamic equilibrium oxygen partial pressure p2.sub.O.sub.2.sub.,eq, wherein said first solid material comprises a steam reforming catalyst, wherein said first solid material is in said first step and under the process conditions of said first step oxidising said at least one reductant to form syngas, said first solid material is in said first step and under the process conditions of said first step catalysing the reaction of said at least one reductant with said steam to form syngas and said first solid material is in said second step and under the process conditions of said second step oxidized by said at least one oxidant while not being oxidized by CO.sub.2, wherein said CO.sub.2 sorbent material is capturing CO.sub.2 in said first step and 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 the second step; and wherein said second solid material is in said first step and under the process conditions of said first step reduced by syngas and said second solid material is in said second step and under the process conditions of said second step oxidized by CO.sub.2 to form CO, preferably by CO.sub.2 released by said CO.sub.2 sorbent material in said second step.

2. The method according to claim 1, wherein said first thermodynamic equilibrium oxygen partial pressure p1.sub.O.sub.2.sub.,eq is at least one order of magnitude larger than said second thermodynamic equilibrium oxygen partial pressure p2.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 and said second step are repeated periodically and/or wherein said method comprising 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 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 first solid material is in said second step and under the process conditions of said second step not being oxidized by CO.sub.2 and not being oxidized by H.sub.2O.

5. The method according to claim 1, wherein said first step further comprises contacting said first gas stream with a second CO.sub.2 sorbent material and wherein said second step further comprises contacting said second gas stream with said second CO.sub.2 sorbent material.

6. The method according to claim 1, wherein said first solid material comprises a metal selected from the group comprising nickel, copper, manganese, iron, cobalt, rhodium, gallium or combinations thereof.

7. The method according to claim 1, wherein said second solid material comprises a metal selected from the group consisting of iron, cerium, tungsten, lanthanum, strontium, iridium, molybdenum, neodymium, zirconium or combinations thereof.

8. The method according to claim 1, wherein said at least one reductant in said first gas stream comprises an organic compound, an alcohol, CO, H.sub.2 or a mixture thereof and/or wherein said at least one oxidant in said second gas stream comprises oxygen or nitrogen oxides.

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

10. An installation for producing a hydrogen rich stream and/or a carbon monoxide rich stream, said installation comprises at least one inlet for introducing a first inlet flow, at least one inlet for introducing a second inlet flow, at least one outlet for providing a first outlet stream comprising said hydrogen rich stream, at least one outlet for providing a second outlet stream comprising said carbon monoxide rich stream, said first inlet flow comprising a stream of steam further comprising at least one reductant and said second inlet flow comprising a stream comprising at least one oxidant, said installation further comprising a first flow path extending from said at least one inlet for introducing said first inlet flow to said at least one outlet for providing said first outlet stream and allowing said first inlet flow to contact a first solid material, a first CO.sub.2 sorbent material and a second solid material and a second flow path extending from at least one inlet for introducing said second inlet flow to said at least one outlet for providing said at least one second outlet stream and allowing said second inlet flow to contact said first solid material, said first CO.sub.2 sorbent material and said second solid material, wherein said first solid material comprises a steam reforming catalyst, said first solid material having a first thermodynamic equilibrium oxygen partial pressure said second solid material having a second thermodynamic equilibrium oxygen partial pressure with said first thermodynamic equilibrium oxygen partial pressure being larger than said second thermodynamic equilibrium oxygen partial pressure 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 oxidising said at least one reductant and said first solid material is in said second flow path and under the process conditions of said second flow path oxidized by said at least one oxidant while not being oxidized by CO2, and wherein said second solid material is in said first flow path and under the process conditions of said first flow path reduced by syngas and said second solid material is in said second flow path and under the process conditions of said second flow path oxidized by CO2.

11. (canceled)

12. An installation according to claim 10, wherein said installation is provided with a first inlet for introducing a first gas stream comprising H.sub.2O and at least one reductant, a second inlet for introducing a second gas stream comprising at least one oxidant, a first outlet for providing a first outlet stream, a second outlet for providing a second outlet stream, and wherein said first flow path is extending from said first inlet to said first outlet and said second flow path is extending from said second inlet to said second outlet.

13. An installation according to claim 10, 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.

14. An installation according to claim 10, wherein said first flow path allows said first inlet flow to contact a second CO.sub.2 sorbent material and said second flow path allows said second inlet flow to contact said second CO.sub.2 sorbent material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0082] The present invention will be discussed in more detail below, with reference to the attached drawings, in which:

[0083] FIG. 1 schematically shows the reaction of a method to produce a hydrogen rich stream and a carbon monoxide rich stream according to the present invention;

[0084] FIG. 2 and FIG. 3 show schematic illustrations of reactors for producing a hydrogen rich stream and a carbon monoxide rich stream according to the present invention;

[0085] FIG. 4 shows the heat released and the corresponding increase in temperature caused by exposing Ni to O.sub.2 as published in “Combined Chemical Looping: New Possibilities for Energy Storage and Conversion”, Energy Fuels 2017, 31, 10, 11509-11514.

DESCRIPTION OF EMBODIMENTS

[0086] 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 drawing 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.

[0087] When referring to the endpoints of a range, the endpoints values of the range are included.

[0088] When describing the invention, the terms used are construed in accordance with the following definitions, unless indicated otherwise.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] Oxygen storage material is defined as a solid intermediate which can exchange oxygen during a chemical looping process.

[0093] 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.

[0094] 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.).

[0095] Organic compound refers to any chemical compound comprising carbon-hydrogen bonds.

[0096] Syngas is defined as a (variable) composition mixture of hydrogen and carbon monoxide.

[0097] A carbon monoxide rich stream refers to a stream comprising at least 10 mol % of carbon monoxide on an inert-free basis, for example at least 20 mol % of carbon monoxide, at least 30 mol % of carbon monoxide or at least 50 mol % of carbon monoxide.

[0098] A hydrogen rich stream refers to a stream comprising at least 50 mol % of hydrogen on a water and inert-free basis, i.e. comprising 50 mol % of hydrogen in the stream excluding water and inert materials. More preferably a hydrogen rich stream refers to a stream comprising at least 60 mol % of hydrogen, or at least 80 mol % of hydrogen.

[0099] FIG. 1 schematically shows the reactions of a method to produce a hydrogen rich stream and/or a carbon monoxide rich stream 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.

[0100] FIG. 2 shows an example of an installation to produce a hydrogen rich stream and a carbon monoxide rich stream based on the reactions shown in FIG. 1. The installation shown in FIG. 2 comprises a fixed bed reactor 1. It should be clear that other types of reactors such as fluidized bed reactors and moving bed reactors can be considered as well.

[0101] 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.xMe.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.

[0102] The first solid material A comprises for example NiO; the second solid material B comprises for example Fe.sub.xO.sub.y 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.

[0103] In the first step fuel and steam are introduced as first gas stream 2. The first gas stream 2 comprises for example an industrial gas stream and steam. In the second step air is introduced as second gas stream 3.

[0104] The reactor 1 shown in FIG. 2 schematically shows a fixed bed reactor 1, having a first zone 4 and a second zone 5. The first zone 4 comprises a first solid material A (for example NiO) 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 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 CO.sub.2 sorbent material C′ of the second zone 5 can be the same as the CO.sub.2 sorbent material C of the first zone 4. Alternatively, the second zone 5 comprises another CO.sub.2 sorbent material C′ than the first zone 4. The first gas stream 2 is introduced to contact first the first zone 4 and subsequently the second zone 5. The second gas stream 3 is introduced to contact first the second zone 5 and then the first zone 4. The reactor 1 is provided with a first outlet 8 providing a hydrogen rich stream and a second outlet 9 providing a carbon monoxide rich stream.

[0105] The following reactions occur in the first step and in the second step, in the different zones represented in FIG. 2:

TABLE-US-00001 1.sup.st step 2.sup.nd step 1.sup.st zone (4) 3Me.sub.1O.sub.x + x CH.sub.4     3 Me.sub.1 + x CO.sub.2 + 2x H.sub.2O Me.sub.3CO.sub.2     Me.sub.3 + CO.sub.2 CH.sub.4 + H.sub.2O     CO + 3 H.sub.2 (catalyzed by Me.sub.1) Me.sub.1 + x/2 O.sub.2 .fwdarw. Me.sub.1O.sub.x CO + H.sub.2O     CO.sub.2 + H.sub.2 (catalyzed by Me.sub.1) Me.sub.3 + CO.sub.2     Me.sub.3CO.sub.2 2.sup.nd zone (5) Me.sub.2O.sub.y + y CO     Me.sub.2 + y CO.sub.2 Me.sub.3CO.sub.2     Me.sub.3 + CO.sub.2 Me.sub.3 + CO.sub.2     Me.sub.3CO.sub.2 Me.sub.2 + y CO.sub.2     Me.sub.2O.sub.y + y CO Me.sub.2O.sub.y + y H.sub.2     Me.sub.2 + y H.sub.2O CO + H.sub.2O     = CO.sub.2 + H.sub.2

[0106] The reactor 1 shown in FIG. 3 has a first zone 6 and a second zone 7. The first zone 6 comprises a first solid material A (for example NiO). The second zone 7 comprises a second solid material B (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 first gas stream 2 is introduced to contact first the first zone 6 and subsequently the second zone 7. The second gas stream 3 follows the same flow path and is first contacting the first zone 6 and subsequently the second zone 7. The reactor 1 is provided with a first outlet 8 providing a hydrogen rich stream and a second outlet 9 providing a carbon monoxide rich stream.

[0107] The following reactions occur in the first step and in the second step, in the different zones represented in FIG. 3:

TABLE-US-00002 1.sup.st step 2.sup.nd step 1.sup.st zone (6) 3Me.sub.1O.sub.x + x CH.sub.4     3 Me.sub.1 + x CO.sub.2 + 2x H.sub.2O Me.sub.1 + x/2 O.sub.2 .fwdarw. Me.sub.1O.sub.x CH.sub.4 + H.sub.2O     CO + 3 H.sub.2 (catalyzed by Me.sub.1) CO + H.sub.2O     CO.sub.2 + H.sub.2 (catalyzed by Me.sub.1) 2.sup.nd zone (7) Me.sub.2O.sub.y + y CO     Me.sub.2 + y CO.sub.2 Me.sub.3CO.sub.2     Me.sub.3 + CO.sub.2 Me.sub.3 + CO.sub.2     Me.sub.3CO.sub.2 Me.sub.2 + y CO.sub.2     Me.sub.2O.sub.y + y CO Me.sub.2O.sub.y + y H.sub.2     Me.sub.2 + y H.sub.2O CO + H.sub.2O     = CO.sub.2 + H.sub.2

Experimental Results

[0108] 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 for gases and Coriolis for vaporised water) 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 He as an internal standard gas for quantification purposes.

[0109] About 40 mg of a standard Ni-based catalyst was used as first solid material in a first zone of the reactor. This zone was further diluted with a solid diluent α-Al.sub.2O.sub.3 in a mass ratio of 1:25 to avoid thermal gradients. A second zone of the reactor comprises a mixture of 1 g of stock CaO (purchased from Sigma-Aldrich) and about 0.4 g of a conventional iron-based oxygen carrier. The first gas stream was introduced in the reactor to follow a flow path whereby first the first zone and subsequently the second zone. The flow path of the second stream followed the same order and contacted first the first zone and subsequently the second zone. This experiment's configuration applied the embodiment displayed in FIG. 3.

[0110] The first gas stream comprises a mixture of methane or CH.sub.4 (fuel) and steam (H.sub.2O) in a 1:1 ratio with a further dilution of helium. Helium (an inert gas) was added for practical reasons to allow interpretation of the experimental data. The molar ratio between the three gases CH.sub.4, H.sub.2O, and He was 1:1:1. The second gas stream comprised He. It is clear that the second gas stream can be amended to comprise an oxidant, for example O.sub.2. 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 fed into the reactor was kept constant at about 2.5 mmol/min.

[0111] 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.

[0112] In a typical cycle, the first step (reduction) and the second step (oxidation) were prolonged to about 20 minutes. During the first step (reduction) of the cyclic method, on an H.sub.2O and He-free basis the first outlet stream had the measured output concentration over its duration: 88% H.sub.2, 10% unreacted CH.sub.4, about 2% CO and less than 0.5% CO.sub.2 on a molar basis. For commercial purposes, H.sub.2O in the first outlet stream could easily be removed by condensing it at room temperature and use of He for commercial application would be unnecessary. The presence of unreacted CH.sub.4 represents an opportunity to further optimise the results (for example, by adding more steam).

[0113] During the second step (oxidation), the second outlet stream had the following molar composition on an He-free basis: 77% H.sub.2, 7% CH.sub.4, 15% CO, and less than 1% CO.sub.2. The presence of H.sub.2 and CH.sub.4 during oxidation when pure He was fed may be indicative of clogged water in the lines being purged into the reactor by He flow and/or the non-ideal response of the switch from first inlet stream to the second inlet stream. Although the use of He 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 an oxidant like air. The very high molar ratio of CO:CO.sub.2 (approximately 26) observed in the experiment proves that a CO-rich stream is feasible from this approach. Further optimisation of the experiment could possibly lead to absence of H.sub.2 and CH.sub.4 and further minimisation of He used in the second outlet stream.

[0114] In another experiment, the phenomenon of heat generation by exposing Ni to O.sub.2 as described in “Combined Chemical Looping: New Possibilities for Energy Storage and Conversion”, Energy Fuels 2017, 31, 10, 11509-11514 was clearly demonstrated. The very high increase in the temperature (of almost 700 K (700° C.)) depicted in FIG. 4 shows the experimental result confirming heat generation.

[0115] The thermodynamic equilibrium partial oxygen pressure of the solid materials used in the above mentioned proof of concept experiment Ni-based catalyst (NiO) as first solid material and (FeO.sub.y) as second solid material are calculated below.

[0116] The total pressure in the experiment was close to the ambient pressure. At the reaction temperature of 1023 K, reactions (11) to (13) should be considered.

2NiO⇄2Ni+O.sub.2  (7)

2Fe.sub.3O.sub.4⇄6FeO+O.sub.2  (8)

2FeO⇄2Fe+O.sub.2  (9)

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 thermodynamic equilibrium oxygen partial pressure of NiO is several orders of magnitude greater than that of FeO.sub.x species, Fe.sub.3O.sub.4 and FeO. The higher thermodynamic equilibrium oxygen partial pressure is important to ensure (nearly) complete utilisation of fuel (by the first solid material—NiO in Table 2). Ni formed during the first step is also important to catalyse the reforming and water gas-shift reactions.

TABLE-US-00003 TABLE 2 Standard thermodynamic properties of solid components at 1023 K (reaction temperature) used in the proof of concept experiment 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.1023 K (Pa) (11) 469748 171 294495 9.3 * 10.sup.−11 (12) 604374 217 381892 3.2 * 10.sup.−15 (13) 526444 128 395705 6.3 * 10.sup.−16