Syngas

Abstract

The disclosure provides a method of producing syngas. The method comprises feeding a first input gas into a reactor. The first input gas comprises oxygen and the reactor comprises an oxygen carrier material, and thereby causes the oxygen carrier material to oxidise. The method further comprises feeding a second input gas into the reactor. The second input gas comprises carbon monoxide and / or a fuel, and thereby causes the oxygen carrier material to be reduced and the carbon monoxide and / or fuel to oxidise to produce a second output gas. The method further comprises purifying the second output gas to obtain a purified gas with a high concentration of carbon dioxide. Finally, the method comprises feeding a third input gas into the reactor. The third input gas comprises the purified gas and a hydrogen gas stream, and thereby causes syngas to be produced.

Description

[0001] Syngas

[0002] The present invention provides a method and apparatus for the production of syngas. The steel industry uses energy-intensive processes and is currently responsible for ~8% of the world’s carbon dioxide output. Due to the threat posed by global warming, there is a growing desire to reduce the amount of carbon dioxide and / or capture carbon dioxide produced in such industries. However, re-building new, more efficient, plants is cost-prohibitive. Furthermore, even modern rebuilt plants would produce some carbon dioxide. Accordingly, there is a desire to devise systems and processes which will reduce the carbon dioxide that is released to the atmosphere in combination with renewable sources. The present invention arose from the inventor’s work in attempting to address the above problems.

[0003] In accordance with a first aspect of the invention, there is provided a method of producing syngas, the method comprising: feeding a first input gas into a reactor, wherein the first input gas comprises oxygen and the reactor comprises an oxygen carrier material, and thereby causing the oxygen carrier material to oxidise; feeding a second input gas into the reactor, wherein the second input gas comprises carbon monoxide and / or a fuel, and thereby causing the oxygen carrier material to be reduced and the carbon monoxide and / or the fuel to oxidise to produce a second output gas; purifying the second output gas to obtain a purified gas with a high concentration of carbon dioxide; and feeding a third input gas into the reactor, wherein the third input gas comprises the purified gas and a hydrogen gas stream, and thereby causing syngas to be produced.

[0004] Advantageously, the method of the first aspect may be applied to existing industrial plants, such as a steel plant. The method could decrease C02emissions of these plants by up to 70 %, which would be of great benefit to public health and the environment. The method would also provide a sellable asset (i.e. syngas). The reactor is preferably a packed bed reactor.

[0005] The oxygen carrier material may comprise a metal and / or a metal oxide. The oxygen carrier material may comprise copper, iron, nickel, an oxide thereof and / or a combination thereof.

[0006] The oxygen carrier material may comprise a plurality of pellets or particles. The plurality of pellets of particles may have an average diameter of between 0.0001 and too mm, between 0.001 and 50 mm, between 0.005 and 25 mm, between 0.01 and 10 mm, between 0.05 and 7.5 mm or between 0.1 and 5 mm.

[0007] The reactor may comprise a support disposed therein, wherein the support is configured to support the oxygen carrier material. The support may comprise a solid inert material, such as aluminium oxide (A12O3), zirconium dioxide (Zr02), magnesium oxide (MgO), monocalcium aluminate (CaAl2O4), titanium dioxide (Ti02) and / or a combination thereof. The weight ratio of the oxygen carrier material to the support maybe between 1:99 and 99:1, between 15:85 and 90:10 or between 30:70 and 80:20.

[0008] The first input gas may be or comprise air. Air may understood to be air taken from the atmosphere and would comprise about 21 vol% oxygen and about 78 vol% nitrogen.

[0009] The first input gas may comprise at least 1 vol% oxygen, more preferably at least 2 vol%, at least 3 vol%, or at least 4 vol% oxygen, and most preferably at least 5 vol%, at least 7 vol% or at least 9 vol % oxygen. The first input gas may comprise less than 90 vol% oxygen, preferably less than 80 vol%, less than 60 vol%, or less than 40 vol% oxygen, and most preferably less than 30 vol%, less than 20 vol% or less than 15 vol% oxygen. The first input gas may comprise between 1 and 100 vol% oxygen, preferably between 2 and 80 vol%, between 3 and 60 vol% or between 4 and 40 vol% oxygen, and most preferably between 5 and 30 vol%, between 7 and 20 vol% or between 9 and 15 vol% oxygen.

[0010] The first gas may comprise an inert gas. The inert gas maybe or comprise nitrogen and / or a noble gas. The noble gas maybe or comprise helium or argon. The first input gas may comprise at least 1 vol% nitrogen, more preferably at least 10 vol%, at least 20 vol%, or at least 40 vol% nitrogen, and most preferably at least 60 vol%, at least 70 vol% or at least 75 vol% nitrogen. The first input gas may comprise less than 97.5 vol% nitrogen, preferably less than 95 vol%, less than 92.5 vol%, or less than 90 vol% nitrogen, and most preferably less than 87.5 vol%, less than 85 vol% or less than 82.5 vol% nitrogen. The first input gas may comprise between 1 and 97.5 vol% nitrogen, preferably between 10 and 95 vol%, between 20 and 92.5 vol% or between 40 and 90 vol% nitrogen, and most preferably between 60 and 87.5 vol%, between 70 and 85 vol% or between 75 and 82.5 vol% nitrogen.

[0011] The first input gas may comprise at least 1 vol% helium, more preferably at least 2 vol%, at least 3 vol%, or at least 4 vol%, and most preferably at least 5 vol%, at least 7 vol% or at least 9 vol % helium. The first input gas may comprise less than too vol% helium, preferably less than 80 vol%, less than 60 vol%, or less than 40 vol% helium, and most preferably less than 30 vol%, less than 20 vol% or less than 15 vol% helium. The first input gas may comprise between 1 and too vol% helium, preferably between 2 and 80 vol%, between 3 and 60 vol% or between 4 and 40 vol% helium, and most preferably between 5 and 30 vol%, between 7 and 20 vol% or between 9 and 15 vol% helium.

[0012] The method may comprise heating the first input gas to a first elevated input temperature prior to feeding the first input gas into the reactor. The method may comprise feeding the first input gas at the first elevated input temperature into the reactor. The first elevated input temperature may be at least 5O°C, preferably at least ioo°C, at least 15O°C or at least 200°C, and more preferably at least 25O°C, at least 3OO°C, at least 35O°C or at least 375°C. In some embodiments, the first elevated input temperature is at least 4OO°C, at least at least 45O°C, at least 500 °C or at least 525°C. The first elevated input temperature may be less than 2,ooo°C, less than i,75O°C, less than i,5OO°C, less than i,25O°C, less than i,ooo°C, less than 9OO°C, less than 8oo°C or less than 75O°C, more preferably less than 7OO°C, less than 65O°C or less than 6oo°C, and most preferably less than 575°C. The first elevated input temperature maybe between 50 and 2,ooo°C, between too and i,75O°C, between 150 and i,5OO°C, between 200 and i,25O°C, between 250 and i,ooo°C, between 300 and 9OO°C, between 350 and

[0013] 8oo°C, between 400 and 7OO°C, between 450 and 65O°C, between 500 and 6oo°C or between 525 and 575°C.

[0014] It may be appreciated that causing the oxygen carrier material to oxidise will be an exothermic process. Accordingly, the temperature within the reactor while the first input gas is fed therein may be higher than the elevated input temperature. The method may comprise controlling a first elevated reactor temperature, wherein the first elevated reactor temperature is the temperature within the reactor while the first input gas is fed therein. The first elevated reactor temperature can be controlled by a number of factors, including controlling the temperature of the first input gas. The first elevated reactor temperature is at least ioo°C, preferably at least 200°C, at least 3OO°C or at least 4OO°C, and more preferably at least 5OO°C, at least 6oo°C, at least 7OO°C or at least 8oo°C. The first elevated reactor temperature maybe less than 2,ooo°C, less than i,75O°C, less than i,5OO°C, less than i,3OO°C, less than i,ioo°C or less than i,ooo°C, more preferably less than 95O°C, or less than 9OO°C. The first elevated reactor temperature may be between too and 2,ooo°C, between 200 and i,75O°C, between 300 and i,5OO°C, between 400 and i,3OO°C, between 500 and i,ioo°C, between 600 and i,ooo°C, between 700 and 95O°C, or between 800 and 9OO°C.

[0015] It may be appreciated that the temperature within the reactor may vary along the length of the reactor. Accordingly, references to the temperature within the reactor may be understood to refer to the mean temperature within the reactor. The mean temperature within the reactor maybe calculated by measuring the temperature at two or more points at different locations along the length of the reactor and calculating the mean thereof.

[0016] In some embodiments, feeding the first input gas into the reactor, and thereby causing the oxygen carrier material to oxidise also produces a first output gas. The method may comprise removing the first output gas from the reactor. The first output gas may be understood to have a lower concentration of oxygen than the first input gas. The first output gas may comprise less than 20 vol% oxygen, more preferably less than 15 vol% oxygen, less than 10 vol% oxygen, less than 5 vol% oxygen or less than 1 vol% oxygen. Due to the process being exothermic, the first output gas will have an elevated temperature. The method may comprise cooling the first output gas. Cooling the first output gas may comprise feeding the first output gas and another fluid through a heat exchanger and thereby transferring heat from the first output gas to the other fluid. In some embodiments, the other fluid is the first input gas, the second input gas, the third input gas, a component thereof and / or a combination thereof. Advantageously, cooling the first output gas may at least partially preheat one or more of the first input gas, the second input gas and / or the third input gas.

[0017] The method may comprise feeding the first input gas into the reactor at a pressure between 0.0001 and too bar, between 0.001 and 50 bar, between 0.005 and 40 bar, between 0.01 and 20 bar, between 0.05 and 15 bar, between 0.1 and 10 bar, between 0.5 and 7.5 or between 1 and 5 bar. Advantageously, the method maybe conducted at any pressure. The pressure may be selected depending upon upstream and / or downstream requirements.

[0018] The method preferably comprises stopping feeding the first input gas into the reactor prior to feeding the second input gas into the reactor.

[0019] The method may comprise stopping feeding the first input gas into the reactor after a first predetermined time. The first predetermined time may vary depending upon a number of factors, and could be determined by a skilled person. Alternatively, the method may comprise stopping feeding the first input gas into the reactor after a concentration of oxygen in the first output gas rises above a predetermined level. The method may comprise purging the reactor between feeding the first input gas into the reactor and feeding the second input gas into the reactor. Pursing the reactor may comprise feeding an inert gas into the reactor. The inert gas may be nitrogen, helium and / or steam. Purging the reactor may comprise feeding the inert gas into the reactor for a predetermined time. Purging the reactor substantially removes oxygen therefrom.

[0020] The second input gas may be or comprise a waste gas. The waste gas may be or comprise a waste gas from a blast furnace, a waste gas from a bio-based process, an offgas from a refinery or chemical process plant and / or a waste gas from a bio-diesel plant.

[0021] The method may comprise cleaning the second input gas prior to feeding the second input gas into the reactor. Cleaning the second input gas may comprise removing a contaminant from the second input gas. The contaminant may be acid gas, ashes and / or sulphur compounds

[0022] Suitable methods for cleaning the second input gas will be known. For instance, cleaning the second input gas may comprise selective adsorption of the contaminant onto an adsorbent. The adsorbent may be a solid adsorbent. The adsorption may occur at a temperature between -50 and 75O°C, between o and 5OO°C or between 20 and 38o°C.

[0023] Alternatively, or additionally, cleaning the second input gas may comprise selective absorption of the contaminant into an absorbent. The absorbent may be a liquid, such as an aqueous solvent. The absorption may occur at a temperature between -25 and 25O°C, between o and ioo°C, between 10 and 5O°C or between 15 and 25°C. The method may comprise regenerating the absorbent.

[0024] Alternatively, or additionally, cleaning the second input gas may comprise filtering the second input gas. For instance, cleaning the second input gas may comprise using a membrane to remove the contaminant.

[0025] The second input gas preferably comprises carbon monoxide.

[0026] The second input gas may comprise at least 1 vol% carbon monoxide, preferably at least 5 vol%, at least 7.5 vol%, at least 10 vol% or at least 12.5 vol% carbon monoxide, and most preferably at least 15 vol% or at least 17.5 vol% carbon monoxide. The second input gas may comprise less than 80 vol%, less than 70 vol%, less than 60 vol%, less than 50 vol%, less than 40 vol%, less than 35 vol% or less than 30 vol% carbon monoxide. The second input gas may comprise between 1 and 80 vol% carbon monoxide, more preferably, between 5 and 70 vol%, between 7.5 and 60 vol%, between 10 and 50 vol% or between 12 and 40 vol% carbon monoxide, and most preferably comprises between 13 and 35 vol%, between 14 and 30 vol% carbon monoxide, between 15 and 27.5 vol% carbon monoxide, between 16 and 25 vol% carbon monoxide or between 17.5 and 22.5 vol% carbon monoxide.

[0027] The fuel maybe an unburnt fuel, a hydrocarbon, an alcohol and / or hydrogen.

[0028] The second input gas may comprise at least 0.01 vol%, at least 0.05 vol%, at least 0.1 vol%, at least 0.5 vol%, at least 1 vol%, at least 2.5 vol%, at least 5 vol%, at least 7.5 vol% or at least 10 vol% fuel. The second input gas may comprise less than 90 vol%, less than 80 vol%, less than 70 vol%, less than 60 vol%, less than 50 vol%, less than 40 vol%, less than 30 vol%, less than 20 vol% or less than 10 vol% fuel. The second input gas may comprise between 0.01 and 90 vol%, between 0.05 and 70 vol%, between 0.1 and 70 vol%, between 0.5 and 60 vol% or between 1 and 50 vol% fuel. In some embodiments, the second input gas may comprise between 0.001 and 40 vol%, between 0.005 and 30 vol%, between 0.01 and 20 vol%, between 0.05 and 15 vol%, between 0.1 and 10 vol%, between 0.5 and 8 vol% or between 1 and 7 vol% fuel. In some embodiments, the second input gas may comprise between 0.5 and 95 vol%, between 1 and 90 vol%, between 2.5 and 80 vol%, between 5 and 70 vol%, between 7.5 and 60 vol% or between 10 and 50 vol% fuel.

[0029] The second input gas may comprise an unburnt fuel and / or a hydrocarbon. The unburnt fuel may be or comprise a hydrocarbon. The hydrocarbon may be a Ci-5hydrocarbon or a C1-3 hydrocarbon. The hydrocarbon may be methane. The second input gas may comprise at least 0.01 vol% unburnt fuel and / or a hydrocarbon, more preferably at least 0.05 vol% unburnt fuel and / or a hydrocarbon or at least 0.1 vol% unburnt fuel and / or a hydrocarbon. In some embodiments, the second input gas may comprises at least 1 vol% unburnt fuel, at least 2.5 vol%, at least 5 vol%, at least 7.5 vol% or at least 10 vol% unburnt fuel and / or a hydrocarbon. The second input gas may comprise less than 90 vol%, less than 80 vol%, less than 70 vol%, less than 60 vol%, less than 50 vol%, less than 40 vol%, less than 30 vol%, less than 20 vol%, less than 10 vol%, less than 5 vol%, less than 1 vol% or less than 0.5 vol% unburnt fuel and / or a hydrocarbon. The second input gas may comprise between 0.01 and 5 vol%, between 0.05 and 1 vol% and between 0.1 and 0.5 vol% unburnt fuel and / or a hydrocarbon. The second input gas may comprise between 1 and 90 vol%, between 2.5 and 80 vol%, between 5 and 70 vol%, between 7.5 and 60 vol% and between 10 and 50 vol% unburnt fuel and / or a hydrocarbon.

[0030] The second input gas may comprise nitrogen. The second input gas may comprise at least 5 vol% nitrogen, more preferably at least 10 vol%, at least 20 vol% or at least 30 vol% nitrogen, and most preferably at least 40 vol% or at least 45 vol% nitrogen. The second input gas may comprise less than 95 vol% nitrogen, more preferably less than 90 vol%, less than 80 vol% or less than 70 vol% nitrogen, most preferably less than 60 vol% or less than 55 vol% nitrogen. The second input gas may comprise between 5 and 95 vol% nitrogen, more preferably between 10 and 90 vol%, between 20 and 80 vol% or between 30 and 70 vol% nitrogen, and most preferably between 35 and 60 vol%, between 40 and 55 vol% or between 45 and 50 vol% nitrogen.

[0031] The second input gas may comprise carbon dioxide. The second input gas may comprise at least 1 vol% carbon dioxide, preferably at least 5 vol%, at least 7.5 vol%, at least 10 vol% or at least 12.5 vol% carbon dioxide, and most preferably at least 15 vol% or at least 17 vol% carbon dioxide. The second input gas may comprise less than 80 vol%, less than 70 vol%, less than 60 vol%, less than 50 vol%, less than 40 vol%, less than 30 vol% or less than 25 vol% carbon dioxide. The second input gas may comprise between 1 and 80 vol% carbon dioxide, more preferably, between 5 and 70 vol%, between 7.5 and 60 vol%, between 10 and 50 vol% or between 12 and 40 vol% carbon dioxide, and most preferably comprises between 14 and 30 vol% or between 15 and 25 between 16 and 22.5 vol% or between 17 and 20 vol% carbon dioxide. The second input gas may comprise hydrogen. The second input gas may comprise at least 0.01 vol% hydrogen, more preferably at least 0.1 vol%, at least 0.5 vol% or at least 1 vol% hydrogen. The second input gas may comprise less than 50 vol%, less than 40 vol%, less than 30 vol%, less than 20 vol%, less than 15 vol% hydrogen, less than 10 vol%, less than 8 vol% or less than 7 vol% hydrogen. The second input gas may comprise between 0.0001 and 50 vol%, between 0.001 and 40 vol%, between 0.005 and 30 vol%, between 0.01 and 20 vol%, between 0.05 and 15 vol% or between 0.1 and 10 vol% hydrogen, and most preferably between 0.5 and 8 vol% or between 1 and 7 vol% hydrogen. The second input gas may comprise an alcohol. The alcohol may comprise methanol, ethanol and / or glycerol. The second input gas may comprise at least 0.1 vol%, at least 0.5 vol%, at least 1 vol% alcohol, at least 2.5 vol% alcohol, at least 5 vol% alcohol, at least 7.5 vol% alcohol or at least 10 vol% alcohol. The second input gas may comprise between 0.1 and too vol% alcohol, between 0.5 and 95 vol% alcohol, between 1 and 90 vol% alcohol, between 2.5 and 80 vol% alcohol, between 5 and 70 vol% alcohol, between 7.5 and 60 vol% alcohol or between 10 and 50 vol% alcohol.

[0032] It is noted that a blast furnace gas typically comprises between about 40 and 60 vol% nitrogen, between about 17 and 25 vol% carbon dioxide, between about 20 and 28% carbon monoxide, between about 1 and 7 vol% hydrogen and up to about 0.2 vol% methane. A biogas would typically comprise between about 40 and 60 vol% carbon dioxide, between about 40 and 60 vol% methane, between about 1 and 5 vol% other gases such as nitrogen and oxygen and less than about 1 vol% hydrogen. A glycerol gas stream would typically comprise between about 10 and 30 vol% glycerol and between about 70 and 90 vol% water. A methanol and / or ethanol gas stream would typically comprise between about 5 and 50 vol% methanol, ethanol or a combination thereof, between about 50 and 99 vol% water and between about 10 and 50 vol% carbon dioxide.

[0033] The second input gas may comprise water. Accordingly, the method may comprise adding steam to a gas stream, preferably a waste gas stream, to provide the second input gas. Advantageously, adding water to the input gas avoids carbon deposition.

[0034] The second input gas may comprise at least 0.1 vol%, at least 1 vol%, at least 2.5 vol%, at least 5 vol%, at least 7.5 vol%, at least 10 vol%, at least 15 vol%, at least 20 vol% or at least 25 vol% water. The second input gas may comprise between o and 70 vol%, between 10 and 60 vol%, between 15 and 50 vol%, between 20 and 40 vol% water or between 25 and 30 vol% water.

[0035] It may be noted that if a blast furnace gas is combined with steam, such that the resulting gas comprise 25 to 30 vol% water then it will also comprise between about 30 and 50 vol% nitrogen, between about 13 and 20 vol% carbon dioxide, between about 15 and 22.5% carbon monoxide, between about 0.75 and 6 vol% hydrogen and up to about 0.16 vol% methane. The method may comprise removing the second output gas from the reactor.

[0036] The second output gas may be understood to comprise a higher concentration of carbon dioxide than the second input gas. The second output gas may comprise at least 5 vol% carbon dioxide, preferably at least 10 vol%, at least 15 vol%, at least 20 vol% or at least 25 vol% carbon dioxide, and most preferably at least 30 vol% or at least 35 vol% carbon dioxide. The second output gas may comprise less than 90 vol%, less than 80 vol%, less than 75 vol%, less than 70 vol%, less than 65 vol%, less than 60 vol% or less than 55 vol% carbon dioxide. The second output gas may comprise between 5 and 90 vol% carbon dioxide, more preferably, between 10 and 80 vol%, between 15 and 75 vol%, between 20 and 70 vol% or between 25 and 65 vol% carbon dioxide, and most preferably comprises between 30 and 60 vol% or between 35 and 55 vol% carbon dioxide.

[0037] The method may comprise heating the second input gas to a second elevated input temperature prior to feeding the second input gas into the reactor. The method may comprise feeding the second input gas at the second elevated input temperature into the reactor. The second elevated input temperature may be at least 5O°C, preferably at least ioo°C, at least 15O°C or at least 200°C, and more preferably at least 25O°C, at least 3OO°C, at least 35O°C, at least 4OO°C or at least 45O°C. In some embodiments, the second elevated input temperature is at least 500 °C or at least 525°C. The second elevated input temperature maybe less than 2,ooo°C, less than i,75O°C, less than i,5OO°C, less than i,25O°C, less than i,ooo°C, less than 9OO°C, less than 8oo°C or less than 75O°C, more preferably less than 7OO°C, less than 65O°C or less than 6oo°C, and most preferably less than 575°C. The second elevated input temperature may be between 50 and 2,ooo°C, between too and i,75O°C, between 150 and i,5OO°C, between 200 and i,25O°C, between 250 and i,ooo°C, between 300 and 9OO°C, between 350 and 8oo°C, between 400 and 7OO°C, between 450 and 65O°C, between 500 and 6oo°C or between 525 and 575°C. Causing the oxygen carrier material to be reduced and the carbon monoxide and / or fuel to oxidise may be an exothermic process. Furthermore, there may be residual heat in the reactor due to previously causing the oxygen carrier material to oxidise therein. Accordingly, the temperature within the reactor while the second input gas is fed therein may be higher than the second elevated input temperature. The method may comprise controlling a second elevated reactor temperature, wherein the second elevated reactor temperature is the temperature within the reactor while the second input gas is fed therein. The second elevated reactor temperature can be controlled by a number of factors, including controlling the second elevated input temperature. The second elevated reactor temperature maybe at least ioo°C, preferably at least 200°C, at least 3OO°C or at least 4OO°C, and more preferably at least 5OO°C, at least 6oo°C, at least 7OO°C or at least 8oo°C. The second elevated reactor temperature may be less than 2,ooo°C, less than i,75O°C, less than i,5OO°C, less than i,3OO°C, less than i,ioo°C or less than i,ooo°C, more preferably less than 95O°C, or less than 9OO°C. The second elevated reactor temperature may be between too and 2,ooo°C, between 200 and i,75O°C, between 300 and i,5OO°C, between 400 and i,3OO°C, between 500 and i,ioo°C, between 600 and i,ooo°C, between 700 and 95O°C, or between 800 and 9OO°C.

[0038] The method may comprise feeding the second input gas into the reactor at a pressure between 0.0001 and 100 bar, between 0.001 and 50 bar, between 0.005 and 40 bar, between 0.01 and 20 bar, between 0.05 and 15 bar, between 0.1 and 10 bar, between 0.5 and 7.5 or between 1 and 5 bar. Advantageously, the method maybe conducted at any pressure. The pressure may be selected depending upon upstream and / or downstream requirements.

[0039] Purifying the second output gas may comprise separating water out of the second output gas. Separating water out of the second output gas may comprise cooling the second output gas to condense the water therefrom. Cooling the second output gas may comprise feeding the second output gas and another fluid through a heat exchanger and thereby transferring heat from the second output gas to the other fluid. In some embodiments, the other fluid is the first input gas, the second input gas, the third input gas, a component thereof and / or a combination thereof. Advantageously, cooling the second output gas may at least partially preheat one or more of the first input gas, the second input gas and / or the third input gas.

[0040] Purifying the second output gas may comprise using a carbon dioxide selective membrane to obtain the purified gas. The membrane may operate with a sweep gas. The sweep gas may be hydrogen gas and / or steam. In embodiments where the sweep gas is hydrogen, the hydrogen may be obtained from the same source as the hydrogen used in the third input gas. The sweep gas may be provided at a pressure between 1 and 20 bar. Alternatively, the membrane may operate without sweep gas. Suitable membranes are known. For instance, the membrane may be a polymeric membrane, a mixed matrix membrane, a graphene-based membrane, a carbon membrane or a supported molten salt membrane.

[0041] In embodiments where the membrane operates with a sweep gas and the sweep gas is or comprises hydrogen, it may be appreciated that some hydrogen may permeate to the retentate side due to the positive driving force dictated by the positive hydrogen partial pressure difference from permeate and retentate side. Accordingly, purifying the second output gas using a carbon dioxide selective membrane may generate a waste gas stream comprising carbon dioxide and hydrogen. The waste gas stream may comprise at least o.i vol%, at least i vol%, at least 2.5 vol%, at least 5 vol% or at least 7.5 vol% carbon dioxide. The waste gas stream may comprise between 1 and 10 vol% carbon dioxide.

[0042] The waste gas stream may comprise at least 0.1 vol%, at least 1 vol%, at least 2.5 vol%, at least 5 vol%, at least 10 vol% or at least 15 vol% hydrogen. The waste gas stream may comprise between 0.1 and 30 vol%, between 1 and 20 vol%, between 2.5 and 15 vol% or between 5 and 10 vol% hydrogen.

[0043] The waste gas stream may comprise at least 60 vol%, at least 70 vol% or at least 80 vol% nitrogen.

[0044] The method may comprise using the waste gas stream as fuel to power a turbine. Accordingly, the method may generate electricity which may be used to power the process.

[0045] Alternatively, the method may comprise combining the waste gas stream with an additional hydrogen gas stream. The waste gas stream and additional hydrogen gas stream may be combined to produce a gas stream with a volumetric ratio of hydrogen to nitrogen of between 1:2 and 10:1, between 1:1 and 5:1, between 2:1 and 4:1 or between 2.5:1 and 3.5:1.

[0046] The method may comprise processing the combined waste and hydrogen gas stream to provide ammonia. Processing the combined waste and hydrogen gas stream may comprise conducting the Haber-Bosch process.

[0047] Purifying the second output gas may comprise first separating water out of the second output gas and subsequently using the carbon dioxide selective membrane to obtain the purified gas.

[0048] It maybe appreciated that the purified gas will have a higher concentration of carbon dioxide than the second output gas. Accordingly, the purified gas may comprise at least 10 vol% carbon dioxide, preferably at least 20 vol%, at least 40 vol%, at least 60 vol% or at least 80 vol% carbon dioxide, and most preferably at least 90 vol% or at least 95 vol% carbon dioxide. The method preferably comprises stopping feeding the second input gas into the reactor prior to feeding the third input gas into the reactor. The method may comprise stopping feeding the second input gas into the reactor after a second predetermined time. The second predetermined time may vary depending upon a number of factors, and could be determined by a skilled person. The first predetermined time may be the same as the second predetermined time. The method may comprise combining the purified gas and the hydrogen gas stream to provide the third input gas. In some embodiments, the method comprises combining the purified gas, the hydrogen gas stream and a further carbon dioxide gas stream to provide the third input gas. The further carbon dioxide gas stream may be from an external source.

[0049] The hydrogen gas stream may be generated from water electrolysis. Accordingly, the method may comprise conducting water electrolysis to generate the hydrogen gas stream. In embodiments where hydrogen is used as a sweep gas and / or added to the waste gas stream, the method may comprise conducting water electrolysis to generate the hydrogen gas stream which is used to produce the third input gas and generating further hydrogen which is used as a sweep gas and / or additional hydrogen gas stream.

[0050] The method may comprise combining the purified gas, the hydrogen gas stream and optionally the further carbon dioxide gas stream to provide the third input gas, such that the third input gas has a molar ratio of hydrogen to carbon dioxide of between 0.1:1 and 5:1, between 0.3:1 and 3:1, between 0.5:1 and 2.5:1, between 0.6:1 and 2:1, between 0.8:1 and 1.5:1 or between 1:1 and 1.3:1.

[0051] The third input gas may comprise at least 1 vol% carbon dioxide, preferably at least 5 vol%, at least 10 vol%, at least 15 vol% or at least 20 vol% carbon dioxide, and most preferably at least 22 vol% or at least 24 vol% carbon dioxide. The third input gas may comprise less than 80 vol%, less than 70 vol%, less than 60 vol%, less than 50 vol%, less than 40 vol%, less than 30 vol% or less than 25 vol% carbon dioxide. The third input gas may comprise between 1 and 80 vol% carbon dioxide, more preferably, between 5 and 70 vol%, between 10 and 60 vol%, between 15 and 50 vol% or between 20 and 40 vol% carbon dioxide, and most preferably comprises between 22 and 30 vol% or between 24 and 25 vol% carbon dioxide.

[0052] The third input gas may comprise at least 1 vol% hydrogen, preferably at least 5 vol%, at least 10 vol%, at least 12.5 vol% or at least 15 vol% hydrogen, and most preferably at least 17 vol% or at least 19 vol% hydrogen. The third input gas may comprise less than 80 vol%, less than 60 vol%, less than 50 vol%, less than 40 vol%, less than 30 vol%, less than 27 vol% or less than 24 vol% hydrogen. The third input gas may comprise between 1 and 80 vol% hydrogen, more preferably, between 5 and 60 vol%, between 10 and 50 vol%, between 12.5 and 40 vol% or between 15 and 30 vol% hydrogen, and most preferably comprises between 17 and 27 vol% or between 19 and 24 vol% hydrogen.

[0053] The third input gas may comprise an inert gas. The inert gas may comprise a noble gas, nitrogen and / or methane. The noble gas maybe or comprise helium and / or argon.

[0054] The third input gas may comprise nitrogen. The third input gas may comprise at least 10 vol% nitrogen, more preferably at least 20 vol%, at least 30 vol% or at least 40 vol% nitrogen, and most preferably at least 45 vol% or at least 47 vol% nitrogen. The third input gas may comprise less than 90 vol% nitrogen, more preferably less than 80 vol%, less than 70 vol% or less than 60 vol% nitrogen, most preferably less than 55 vol% or less than 50 vol% nitrogen. The third input gas may comprise between 10 and 90 vol% nitrogen, more preferably between 20 and 80 vol%, between 30 and 70 vol% or between 40 and 60 vol% nitrogen, and most preferably between 45 and 55 vol% or between 47 and 50 vol% nitrogen.

[0055] The third input gas may comprise at least 0.5 vol%, at least 1 vol%, at least 2 vol%, at least 3 vol% or at least 4 vol% noble gas and / or methane, and most preferably at least 5 vol% noble gas and / or methane. The third input gas may comprise less than 40 vol%, less than 30 vol%, or less than 20 vol% noble gas and / or methane, and most preferably less than 15 vol%, less than 10 vol% or less than 8 vol% noble gas and / or methane. The third input gas may comprise between 0.5 and 50 vol%, between 1 and 30 vol% or between 2 and 20 vol% noble gas and / or methane, and most preferably between 3 and 15 vol%, between 4 and 10 vol% or between 5 and 8 vol% noble gas and / or methane. The third input gas may comprise carbon monoxide. The third input gas may comprise at least 0.01 vol%, at least 0.1 vol%, at least 0.5 vol% or at least 1 vol carbon monoxide. The third input gas may comprise less than 80 vol%, less than 60 vol%, less than 50 vol%, less than 40 vol%, less than 30 vol%, less than 25 vol%, less than 20 vol%, less than 15 vol%, less than 10 vol% or less than 5 vol% carbon monoxide. The third input gas may comprise between 0.01 and 40 vol% or between 0.1 and 20 vol% hydrogen, and most preferably comprises between 0.5 and 10 vol% or between 1 and 5 vol% carbon monoxide.

[0056] The method may comprise heating the third input gas to a third elevated input temperature prior to feeding the third input gas into the reactor. The method may comprise feeding the third input gas at the third elevated input temperature into the reactor. The third elevated input temperature may be at least 5O°C, preferably at least ioo°C, at least 15O°C or at least 200°C, and more preferably at least 25O°C, at least 3OO°C or at least 325°C. The third elevated input temperature may be less than i,5OO°C, less than i,ooo°C, less than 8oo°C or less than 6oo°C, more preferably less than 5OO°C, less than 45O°C, or less than 4OO°C, and most preferably less than 375°C.

[0057] The third elevated input temperature may be between 50 and i,5OO°C, between too and i,ooo°C, between 150 and 8oo°C, between 200 and 6oo°C, between 200 and 5OO°C, between 250 and 45O°C, between 300 and 4OO°C or between 325 and 375°C. There may be residual heat in the reactor due to previously causing the oxygen carrier material to oxidise therein and / or due to previously causing the oxygen carrier material to be reduced and the carbon monoxide and / or fuel to oxidise therein. Accordingly, the temperature within the reactor while the third input gas is fed therein may be higher than the third elevated input temperature. The method may comprise controlling a third elevated reactor temperature, wherein the third elevated reactor temperature is the temperature within the reactor while the third input gas is fed therein. The third elevated reactor temperature can be controlled by a number of factors, including controlling the third elevated input temperature. The third elevated reactor temperature may be at least ioo°C, preferably at least 200°C, at least 3OO°C or at least 4OO°C, and more preferably at least 5OO°C, at least 6oo°C, at least 7OO°C or at least 8oo°C. The third elevated reactor temperature may be less than 2,ooo°C, less than i,75O°C, less than i,5OO°C, less than i,3OO°C, less than i,ioo°C or less than i,ooo°C, more preferably less than 95O°C, or less than 9OO°C. The third elevated reactor temperature may be between too and 2,ooo°C, between 200 and i,75O°C, between 300 and i,5OO°C, between 400 and i,3OO°C, between 500 and i,ioo°C, between 600 and i,ooo°C, between 700 and 95O°C, or between 800 and 9OO°C. The method may comprise feeding the third input gas into the reactor at a pressure between 0.0001 and too bar, between 0.001 and 50 bar, between 0.005 and 40 bar, between 0.01 and 20 bar, between 0.05 and 15 bar, between 0.1 and 10 bar, between 0.5 and 7.5 or between 1 and 5 bar. Advantageously, the method may be conducted at any pressure. The pressure may be selected depending upon upstream and / or downstream requirements.

[0058] The method may comprise removing the syngas from the reactor.

[0059] The method may comprise cooling the syngas. Cooling the syngas may comprise feeding the syngas and another fluid through a heat exchanger and thereby transferring heat from the syngas to the other fluid. In some embodiments, the other fluid is the first input gas, the second input gas, the third input gas, a component thereof and / or a combination thereof. Advantageously, cooling the syngas may at least partially preheat one or more of the first input gas, the second input gas and / or the third input gas.

[0060] The syngas preferably comprises hydrogen gas and carbon monoxide. The syngas preferably has a molar ratio of hydrogen to carbon monoxide of between 0.5:1 and 5:1, between 1:1 and 3:1, between 1.25:1 and 2.75:1, between 1.5:1 and 2.5:1, between 1.8:1 and 2.2:1 or between 1.9:1 and 2.1:1.

[0061] The method may comprise stopping feeding the third input gas into the reactor after a third predetermined time. The third predetermined time may vary depending upon a number of factors, and could be determined by a skilled person. The third predetermined time may be the same as the first and / or second predetermined times.

[0062] In a preferred embodiment, the method comprises: in a first step: feeding a first input gas into a first reactor, wherein the first input gas comprises oxygen and the reactor comprises an oxygen carrier material, and thereby causing the oxygen carrier material in the first reactor to oxidise; simultaneously feeding a second input gas into a second reactor, wherein the second reactor comprises an oxygen carrier material and the second input gas comprises carbon monoxide and / or a fuel, and thereby causing the oxygen carrier material to be reduced and the carbon monoxide and / or fuel to oxidise to produce a second output gas in the second reactor; purifying the second output gas to obtain a purified gas with a high concentration of carbon dioxide; and simultaneously feeding a third input gas into a third reactor, wherein the third reactor comprises an oxygen carrier material and the third input gas comprises the purified gas and a hydrogen gas stream, and thereby causing syngas to be produced in the third reactor; and subsequently switching the feeds of the input gases such that a second step comprises: feeding the first input gas into the third reactor, and thereby causing the oxygen carrier material in the third reactor to oxidise; simultaneously feeding the second input gas into the first reactor, and thereby causing the oxygen carrier material to be reduced and the carbon monoxide and / or fuel to oxidise to produce the second output gas in the first reactor; purifying the second output gas to obtain a purified gas with a high concentration of carbon dioxide; and simultaneously feeding the third input gas into the second reactor, and thereby causing syngas to be produced in the second reactor; and subsequently switching the feeds of the input gases such that a third step comprises: feeding the first input gas into the second reactor, and thereby causing the oxygen carrier material in the second reactor to oxidise; simultaneously feeding the second input gas into the third reactor, and thereby causing the oxygen carrier material to be reduced and the carbon monoxide and / or fuel to oxidise to produce the second output gas in the third reactor; purifying the second output gas to obtain a purified gas with a high concentration of carbon dioxide; and simultaneously feeding the third input gas into the first reactor, and thereby causing syngas to be produced in the first reactor.

[0063] The above method may further comprise subsequently switching the feeds of the input gases such that the above method is repeated. The above method may be repeated any number of times, as desired. Prior to commencing the first step of the above preferred embodiment, the method may comprise: in a first pre-step: starting the flow of the first input gas and feeding the first input gas into the third reactor, and thereby causing the oxygen carrier material in the third reactor to oxidise; subsequently switching the feed of the first input gases and starting the flow of the second input gas, such that a second pre-step comprises: feeding the first input gas into the second reactor, and thereby causing the oxygen carrier material in the second reactor to oxidise; simultaneously feeding the second input gas into the third reactor, and thereby causing the oxygen carrier material to be reduced and the carbon monoxide and / or fuel to oxidise to produce the second output gas in the third reactor; and purifying the second output gas to obtain a purified gas with a high concentration of carbon dioxide.

[0064] The method may then comprise switching the feeds of the first and second input gases and starting the flow of the third input gas, and commencing the first step of the preferred embodiment, as defined above.

[0065] The method may comprise switching the feeds of the input gases after a predetermined time. The predetermined time may vary depending upon a number of factors, and could be determined by a skilled person. Alternatively, the method may comprise switching the feeds after a concentration of oxygen in the first output gas rises above a predetermined level.

[0066] In accordance with a second aspect, there is provided a method for producing a liquid fuel, the method comprising: conducting the method of the first aspect to produce a syngas; and converting the syngas into a liquid fuel.

[0067] The method may comprise cooling the syngas. The syngas may be cooled to less than 7OO°C, less than 6oo°C, less than 5OO°C or less than 4OO°C. The syngas may be cooled to a temperature between 50 and 700°C, between too and 6oo°C, between 150 and 5OO°C or between 200 and 4OO°C.

[0068] Cooling the syngas may comprise feeding the syngas and another fluid through a heat exchanger and thereby transferring heat from the syngas to the other fluid. In some embodiments, the other fluid is the first input gas, the second input gas, the third input gas, a component thereof and / or a combination thereof. Advantageously, cooling the syngas may at least partially preheat one or more of the first input gas, the second input gas and / or the third input gas.

[0069] Converting the syngas into a liquid fuel may comprise using a Fischer-Tropsch process. Accordingly, the method may comprise feeding the syngas into a Fischer-Tropsch reactor. It may be appreciated that a Fischer-Tropsch reactor is configured to convert carbon monoxide and hydrogen into hydrocarbons.. The Fischer-Tropsch reactor may comprise a Fischer-Tropsch catalyst.

[0070] The Fischer-Tropsch reactor may produce a syncrude output stream. The syncrude output stream may be split to provide a light gas stream and a further product stream. The further product stream may be further split to provide a liquid product stream and a long chain hydrocarbon stream.

[0071] The light gas stream may comprise hydrogen. The light gas stream may comprise carbon monoxide. The light gas stream may comprise light weight hydrocarbons. Light weight hydrocarbons maybe understood to be C1-4, C1-3 or C1-2 hydrocarbons.

[0072] At least a portion of the light gas stream may be fed back into the Fischer-Tropsch reactor. Advantageously, this will increase the overall CO conversion.

[0073] Alternatively, or additionally, at least a portion of the light gas stream may form part of the second input gas stream. For instance, at least a portion of the light gas stream may be combined with a waste gas stream, and optionally steam, to provide the second input gas stream.

[0074] The liquid product stream may comprise C3-21, C4-18 or C5-16 hydrocarbons. The liquid produce stream. The method may comprise separating the liquid product stream to produce two or more liquid products comprising hydrocarbons with different molecular weights.

[0075] The long chain hydrocarbon stream may comprise hydrocarbons with at least 17 carbons, at least 20 carbons or at least 22 carbons. The method may comprise cracking the long chain hydrocarbons to produce a medium chain hydrocarbon stream. The medium chain hydrocarbon stream may comprise C3-21, C4-18 or C5-16 hydrocarbons. The method may comprise combining the medium chain hydrocarbon stream and the liquid produce stream. The combined medium chain hydrocarbon and liquid produce stream may then be separated to produce two or more liquid products comprising hydrocarbons with different molecular weights. Alternatively, the method may comprise separately comprise separating the medium chain hydrocarbon stream to produce two or more liquid products comprising hydrocarbons with different molecular weights.

[0076] In accordance with a third aspect, there is provided an apparatus for producing a syngas, the apparatus comprising: a reactor; an oxygen carrier material disposed in the reactor; an input valve, configured to selectively feed an input gas into the reactor; a purifier, configured to purifying an output gas to obtain a purified gas with a high concentration of carbon dioxide; an output valve configured to selectively feed a second output gas from the reactor to the purifier; and a purified conduit, extending between the purifier and the input valve, and configured to feed the purified gas from the purifier to the input valve.

[0077] The apparatus of the third aspect may be used to conduct the method of the first aspect. The reactor and the oxygen carrier material may be as defined in relation to the first aspect.

[0078] The apparatus may comprise a first input gas store configured to store the first input gas. The apparatus may comprise a first input gas conduit extending between the first input gas store and the input valve. The apparatus may comprise a second input gas store configured to store the second input gas. Alternatively, or additionally, the apparatus may comprise a second input gas store generator configured to generate the second input gas. The apparatus may comprise a second input gas conduit extending between the second input gas store and / or generator and the input valve.

[0079] The purifier may comprise a carbon dioxide selective membrane. The membrane may be as defined in relation to the first aspect. The purifier may comprise a sweep gas feeder configured to feed a sweep gas to the carbon dioxide selective membrane. The sweep gas feeder may be configured to feed the sweep gas to the membrane at a pressure between i and 20 bar.

[0080] The apparatus may comprise a waste gas conduit, configured to transport a waste gas from the membrane, preferably from a retentate side of the membrane.

[0081] The waste gas conduit may extend between the membrane and a combustor. The waste gas conduit may extend between a retentate side of the membrane and the combustor.

[0082] The combustor may comprise a turbine. The combustor may be configured to combust the waste gas, thereby cause the turbine to rotate and thereby generate electricity.

[0083] Alternatively, the waste gas conduit may extend between the membrane and a Haber- Bosch reactor. The waste gas conduit may extend between a retentate side of the membrane and the Haber-Bosch reactor. The Haber-Bosch reactor may be configured to convert nitrogen and hydrogen into ammonia.

[0084] The apparatus may comprise a hydrogen feeder configured to feed hydrogen into the waste gas conduit. The hydrogen feeder may comprise a hydrogen valve configured to control the volume of hydrogen gas fed into the waste gas conduit relative to the volume of waste gas. The valve may comprise a flow control valve.

[0085] The input valve maybe configured to selectively feed first, second and third input gases into the reactor. Selectively feed may be understood to mean that the input valve is configured to selectively feed the first, second and third input gases separately into the reactor. Accordingly, only one of the first, second and third input gases may be fed into the reactor at any given time. In this embodiment, the input valve may be a four- way valve comprising three inlet ports and one outlet port. The input valve may be configured to selectively control which inlet port is in fluid communication with the outlet port. Alternatively, the apparatus may comprise first, second and third input valves, wherein the first input valve is configured to selectively feed a first input gas into the reactor, the second input valve is configured to feed a second input gas into the reactor and the third input valve is configured to selectively feed a third input gas into the reactor. The apparatus may comprise a first heater configured to heat a first inlet gas. The heater may comprise a first heat exchanger. The first heat exchanger may be configured to transfer heat from an outlet gas to the first inlet gas. The first heater may be disposed upstream of the input valve. The apparatus may comprise a second heater configured to heat a second inlet gas. The heater may comprise a second heat exchanger. The second heat exchanger may be configured to transfer heat from an outlet gas to the second inlet gas. The second heater may be disposed upstream of the input valve. The apparatus may comprise a third heater configured to heat a third inlet gas. The heater may comprise a third heat exchanger. The third heat exchanger may be configured to transfer heat from an outlet gas to the third inlet gas. The third heater may be disposed upstream of the input valve. The output valve may be configured to remove first, second and third output gases from the reactor. The output valve maybe configured to selectively control where the first, second and third output gases are fed after being removed from the reactor. Accordingly, the output valve may be configured to selectively feed the first output gas from the reactor to a first output gas conduit or vent the first output gas, selectively feed the second output gas from the reactor to the purifier and selectively feed the third output gas from the reactor to a third output gas conduit. It may be appreciated that only one of the first, second and third output gases may be fed through the output valve at any given time. In this embodiment, the output valve may be a four-way valve comprising one inlet port and three outlet ports. The output valve maybe configured to selectively control which outlet port is in fluid communication with the inlet port. Alternatively, the apparatus may comprise first, second and third output valves, wherein the first output valve is configured to selectively feed a first output gas to a first output gas conduit or vent the first output gas, the second output valve is configured to selectively feed a second output gas to the purifier and the third output valve is configured to selectively feed a third output gas to a third output gas conduit. Accordingly, when the reactor is generating a first output gas, the first output valve may be open and configured to feed the output gas from the reactor to the output gas conduit and the second and third output valves may be closed. Similarly, when the reactor is generating a second output gas, the second output valve may be open and configured to feed the output gas from the reactor to the purifier and the first and third output valves may be closed. Furthermore, when the reactor is generating a third output gas, the third output valve may be open and configured to feed the output gas from the reactor to the third output gas conduit and the first and second output valves may be closed.

[0086] The apparatus may comprise a second output gas conduit. Accordingly, the second output gas conduit may extend between the output valve and the purifier.

[0087] Alternatively, the second output gas conduit may extend between the second output valve and the purifier.

[0088] The first output gas conduit may be configured to vent the first output gas to the atmosphere.

[0089] The third output gas conduit may be configured to feed the third output gas to a store.

[0090] Alternatively, the third output gas conduit may be configured to feed the third output gas to a Fischer-Tropsch reactor. Accordingly, the apparatus maybe used to conduct the method of the second aspect. The Fischer-Tropsch reactor may be configured to convert sungas into liquid fuel using a Fischer-Tropsch process. Accordingly, the Fischer-Tropsch reactor may comprise a Fischer-Tropsch catalyst.

[0091] The apparatus may comprise a cooler configured to cool the third output gas. The cooler may comprise a further heat exchanger. The further heat exchanger may be configured to transfer heat from the third outlet gas to an inlet gas. The cooler may be disposed downstream of the outlet valve or the third outlet valve.

[0092] The apparatus may comprise a splitter configured to split a syncrude generated in the Fischer-Tropsch reactor into at least two and preferably three streams. The splitter may split the syncrude based upon the molecular weight of the components thereof. The three output streams may be as defined above.

[0093] The apparatus may comprise a first light stream conduit configured to transport at least a portion of a light gas stream from the splitter into the Fischer-Tropsch reactor. The apparatus may comprise a second light stream conduit configured to transport at least a portion of a light gas stream from the splitter to the input valve or the second input valve. The apparatus may comprise a cracker, configured to crack long chain hydrocarbons.

[0094] The apparatus may comprise a long chain hydrocarbon conduit configured to transport a long chain hydrocarbon stream from the splitter to the cracker.

[0095] The apparatus may comprise a fractionation unit configured to separate liquid products. The apparatus may comprise a first liquid product conduit configured to transport a liquid product stream from the splitter to the fractionation unit. The apparatus may comprise a second liquid product conduit configured to transport a liquid product stream from the cracker to the fractionation unit. The apparatus may comprise one or more liquid product stores. The apparatus may comprise one or more conduits configured to transport a liquid product from the splitter and or the cracker to the liquid product store. Alternatively, the apparatus may comprise a plurality of conduit configured to separately transport separated liquid products from the fractionation unit to respective liquid product stores.

[0096] The apparatus may comprise a controller.

[0097] The controller may be configured to control the input valve, or the first, second and third input valves. The controller may be configured to control the input valve, or the first, second and third input valves, to feed a first input gas into the reactor, to subsequently feed a second input gas into the reactor and to then subsequently feed a third input gas into the reactor. The controller may be configured control the input valve, or the first, second and third input valves, to feed the first input gas into the reactor for a first predetermined time. The controller may be configured control the input valve, or the first, second and third input valves, to feed the second input gas into the reactor for a second predetermined time. The controller may be configured control the input valve, or the first, second and third input valves, to feed the third input gas into the reactor for a third predetermined time.

[0098] The controller may be configured to control the output valve or the first, second and third output valves. When the first input gas is fed into the reactor a first output gas may be generated. The controller may be configured to control the output valve, or the first, second and third output valves, to feed the first output gas to the first output gas conduit or vent the first output gas. When the second input gas is fed into the reactor the second output gas will be generated. The controller may be configured to control the output valve, or the first, second and third output valves, to feed the second output gas to the purifier. When the third input gas is fed into the reactor the third output gas will be generated. The controller may be configured to control the output valve, or the first, second and third output valves, to feed the third output gas to the third output gas conduit.

[0099] The apparatus may comprise a condenser, configured to condense water out of the second output gas. The condenser may be disposed downstream of the output valve and upstream of the purifier. The condenser may comprise a heat exchanger configured to transfer heat out of the second output gas. In some embodiments, the condenser may comprise one or more of the first, second and third heat exchangers.

[0100] The apparatus may comprise a hydrogen conduit configured to feed hydrogen from a hydrogen store and / or generator to the input valve. In some embodiments, the hydrogen conduit is configured to feed hydrogen from a hydrogen store and / or generator to the third input valve.

[0101] In some embodiments, the sweep gas feeder comprises a sweep gas conduit which extends between the hydrogen store and / or generator and the membrane, and is configured to feed hydrogen gas from the hydrogen store and / or generator to the membrane. In some embodiments, the hydrogen feeder comprises a further hydrogen conduit which extends between the hydrogen store and / or generator and the waste gas conduit, and is configured to feed hydrogen gas from the hydrogen store and / or generator to the waste gas conduit.

[0102] The hydrogen generator may comprise an electrolyser configured to electrolyse water and generate hydrogen.

[0103] The apparatus may comprise a flow control valve configured to control the flow of the purified gas. The apparatus may comprise a flow control valve configured to control the flow of the hydrogen.

[0104] The controller may be configured to control the flow control valves to obtain a desired molar ratio of carbon dioxide to hydrogen. The molar ratio may be as defined in the flit aspect.

[0105] In a preferred embodiment, the apparatus comprises: first, second and third reactors; an oxygen carrier material disposed in each of the first, second and third reactors; first, second and third input valves configured to selectively feed first, second and third input gases into the first, second and third reactors; a purifier, configured to purifying an output gas to obtain a purified gas with a high concentration of carbon dioxide; first, second and third output valves, wherein at least one of the first, second and third output valves is configured to selectively feed a second output gases from the reactor to the purifier; and a purified conduit, extending between the purifier and at least one of the first, second and third input valves, and configured to feed the purified gas from the purifier to the at least one of the first, second and third input valves.

[0106] The controller may be configured to control the first, second and third input valves.

[0107] In one embodiment, the first input valve is configured to selectively feed first, second and third input gases into the first reactor, the second input valve is configured to selectively feed first, second and third input gases into the second reactor and the third input valve is configured to selectively feed first, second and third input gases into the third reactor. Selectively feed may be understood to mean that each input valve is configured to selectively feed the first, second and third input gases separately into the reactor. Accordingly, only one of the first, second and third input gases may be fed into a specific reactor at any given time. In this embodiment, the first second and third input valves may each be a four- way valve comprising three inlet ports and one outlet port. The first, second and third input valves may be configured to selectively control which inlet port is in fluid communication with the outlet port. In this embodiment, the first input gas conduit may comprise multiple conduits and / or a branched conduit. The multiple conduits and / or branched conduit may extend between the first input gas store and the first, second and third input valves and may be configured to feed the first input gas from the first input gas store to the first, second and third input valves. The multiple conduits and / or branched conduit may extend between the first input gas store and a first input port of each of the first, second and third input valves and may be configured to feed the first input gas from the first input gas store to the first input port of each of the first, second and third input valves.

[0108] In this embodiment, the second input gas conduit may comprise multiple conduits and / or a branched conduit. The multiple conduits and / or branched conduit may extend between the second input gas store and / or generator and the first, second and third input valves and may be configured to feed the second input gas from the second input gas store and / or generator to the first, second and third input valves. The multiple conduits and / or branched conduit may extend between the second input gas store and / or generator and a second input port of each of the first, second and third input valves and may be configured to feed the second input gas from the second input gas store and / or generator to the second input port of each of the first, second and third input valves. In this embodiment, the purified conduit may comprise multiple conduits and / or a branched conduit. The multiple conduits and / or branched conduit may extend between the purifier and the first, second and third input valves and may be configured to feed the purified gas from the purifier to the first, second and third input valves. The multiple conduits and / or branched conduit may extend between the purifier and a third input port of each of the first, second and third input valves and may be configured to feed the purified gas from the purifier to the third input port of each of the first, second and third input valves.

[0109] In this embodiment, the hydrogen conduit may comprise multiple conduits and / or a branched conduit. The multiple conduits and / or branched conduit may extend between the hydrogen store and / or generator and the first, second and third input valves and may be configured to feed hydrogen from the hydrogen store and / or generator to the first, second and third input valves. The multiple conduits and / or branched conduit may extend between the hydrogen store and / or generator and a third input port of each of the first, second and third input valves and may be configured to feed hydrogen from the hydrogen store and / or generator to the third input port of each of the first, second and third input valves.

[0110] In an alternative embodiment, the first input valve is configured to selectively feed a first input gas into the first, second and third reactors, the second input valve is configured to feed a second input gas into the first, second and third reactors and the third input valve is configured to selectively feed a third input gas into the first, second and third reactors. Selectively feed may be understood to mean that each input valve may only feed input gas into one reactor at any given time. In this embodiment, the first second and third input valves may each be a four- way valve comprising one inlet port and three outlet ports. The first, second and third input valves may be configured to selectively control which outlet port is in fluid communication with the inlet port.

[0111] In this embodiment, the first input gas conduit may extend between the first input gas store and the first input valve and may be configured to feed the first input gas from the first input gas store to the first input valve.

[0112] In this embodiment, the second input gas conduit may extend between the second input gas store and / or conduit and the second input valve and may be configured to feed the second input gas from the second input gas store and / or conduit to the second input valve.

[0113] In this embodiment, the purified conduit may extend between the purifier and the third input valve and may be configured to feed the purified gas from the purifier to the third input valve. In this embodiment, the hydrogen conduit may extend between the hydrogen store and / or generator and the third input valve and may be configured to feed hydrogen gas from the hydrogen store and / or generator to the third input valve. The controller may be configured to control the first, second and third input valves, to: simultaneously feed a first input gas into the first reactor, a second input gas into the second reactor and a third input gas into the third reactor; to subsequently simultaneously feed the second input gas into the first reactor, the third input gas into the second reactor and the first input gas into the third reactor; and to then subsequently feed the third input gas into the first reactor, the first input gas into the second reactor and the second input gas into the third reactor.

[0114] The controller may be configured to repeat the steps above one or more times. The controller may be configured control the first, second and third input valves, to switch the input gases after a predetermined time.

[0115] In one embodiment, the first output valve is configured to selectively remove first, second and third output gases from the first reactor, the second input valve is configured to selectively remove first, second and third output gases from the second reactor and the third output valve is configured to selectively remove first, second and third output gases from the third reactor. Selectively remove may be understood to mean that each output valve is configured to selectively feed the first output gas from the reactor to a first output gas conduit or vent the first output gas, selectively feed the second output gas from the reactor to the purifier and selectively feed the third output gas from the reactor to a third output gas conduit. Accordingly, only one of the first, second and third output gases may be fed out of a specific reactor at any given time. In this embodiment, the first second and third output valves may each be a four-way valve comprising one inlet port and three outlet ports. The first, second and third output valves may be configured to selectively control which outlet port is in fluid communication with the inlet port.

[0116] In this embodiment, a first output port of each of the first, second and third output valves may be configured to feed the first output gas into a first output gas conduit and / or vent the first output gas directly to the atmosphere. In this embodiment, a second output port of each of the first, second and third output valves may be configured to feed the second output gas into the second output gas conduit. In this embodiment, a third output port of each of the first, second and third output valves may be configured to feed the third output gas into the third output gas conduit. In an alternative embodiment, the first output valve is configured to selectively remove a first input gas from the first, second and third reactors, the second output valve is configured to remove a second output gas from the first, second and third reactors and the third output valve is configured to selectively remove a third output gas from the first, second and third reactors. Selectively remove may be understood to mean that each output valve may only remove output gas from one reactor at any given time. In this embodiment, the first second and third output valves may each be a four-way valve comprising three inlet ports and one outlet port. The first, second and third output valves may be configured to selectively control which inlet port is in fluid communication with the outlet port.

[0117] In this embodiment, the first output valve may be configured to feed the first output gas into a first output gas conduit and / or vent the first output gas directly to the atmosphere. In this embodiment, the second output valve may be configured to feed the second output gas into the second output gas conduit. In this embodiment, the third output valve may be configured to feed the third output gas into the third output gas conduit.

[0118] The controller may be configured to control the first, second and third output valves, to: simultaneously remove a first output gas from the first reactor, a second output gas from the second reactor and a third output gas from the third reactor; to subsequently simultaneously remove the second output gas from the first reactor, the third output gas from the second reactor and the first output gas from the third reactor; and to then subsequently remove the third output gas from the first reactor, the first output gas from the second reactor and the second output gas from the third reactor.

[0119] Preferably, the controller is configured to remove the first output gas from the first reactor, the second output gas from the second reactor and the third output gas from the third reactor simultaneously to feeding the first input gas into the first reactor, the second input gas into the second reactor and the third input gas into the third reactor.

[0120] Similarly, preferably the controller is configured to remove the second output gas from the first reactor, the third output gas from the second reactor and the first output gas from the third reactor feeding the second input gas into the first reactor, the third input gas into the second reactor and the first input gas into the third reactor. Similarly, preferably the controller is configured to remove the third output gas from the first reactor, the first output gas from the second reactor and the second output gas from the third reactor simultaneously to feeding the third input gas into the first reactor, the first input gas into the second reactor and the second input gas into the third reactor.

[0121] All features described herein (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined with any of the above aspects in any combination, except combinations where at least some of such features and / or steps are mutually exclusive.

[0122] For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:-

[0123] Figure 1 is a schematic diagram showing the concept of a chemical looping reverse water-gas shift (CL-RWGS) system;

[0124] Figure 2 shows the integration of CL-RWGS for liquid fuels; Figure 3 is a process flow diagram of an embodiment of the invention;

[0125] Figure 4 is a schematic diagram of the CL-RWGS process for the C02conversion to syngas;

[0126] Figure 5 is a piping and instrumentation (P&ID) of the experimental setup located at the University of Manchester; Figure 6 provides graphs showing the effect of feed composition (H2 / C02molar ratio) and temperature on the a) H2 / C0 and b) C0 / C02molar ratio in the product gases during the RWGS process;

[0127] Figure 7 is a graph showing the effect of feed composition (H2 / C02molar ratio) and temperature on the H2 / C0 molar ratio in the product during the RWGS process. Experimental results (light bar) are compared with the theoretical results based on a simulation (dark bar);

[0128] Figure 8 provides graphs showing the effect of temperature and pressure on the a) H2 / C0 and b) C0 / C02molar ratio in the product during the RWGS process at H2 / C02molar ratio of 1.3 in the feed. Experimental results for the H2 / C0 molar ratio are compared with the equilibrium findings; Figure 9 shows a) molar composition and b) temperature profile of output gas during one complete cycle of CL-RWGS process at 500 °C, 1 bar and H2 / C02molar ratio of 1.3 in the feed. The temperature profile is measured by thermocouples (TC3, TC4, TC5, TC6, TC7 and TC8), where the number of the thermocouple indicates its axial position inside the reactor;

[0129] Figure 10 shows the molar composition of product gases (on a diy basis) over 10 complete cycles of CL-RWGS process at 550 °C, 1 bar and H2 / C02molar ratio of 1.3 in the feed;

[0130] Figure 11 provides a schematic diagram showing how the invention may be integrated into a system for liquid fuels synthesis;

[0131] Figure 12 provides a schematic diagram showing how the system may be modified to enable energy recovery;

[0132] Figure 13 provides a schematic diagram showing how the invention may be integrated into a system for ammonia synthesis; Figure 14 provides graphs showing the effect of feed composition (H2 / C02molar ratio) and temperature on the H2 / C0 molar ratio in the product gases during the RWGS process at (a) 1 bar, (b) 5 bar and (c) 8 bar; and

[0133] Figure 15 shows molar composition of output gas during one complete cycle of CL- RWGS process at 600 °C with oxidation using 10% 02, reduction using 20% H2and RWGS using 10% C02and 20% H2at (a) 1 and (b) 5 bar.

[0134] Example 1 - The Chemical Looping Reverse Water-Gas Shift (CL-RWGS) System

[0135] A schematic diagram illustrating an embodiment of the invention is provided in Figure 1 and a process flow diagram showing the same process is provided in Figure 3.

[0136] In particular, Figure 1 shows a packed bed reactor comprising an oxygen carrier, typically copper, iron, nickel or a combination thereof. These reactors are stainless steel (SS) adiabatic vessels with refractory lined materials inside which can withstand high temperatures and high pressure at the same time. It may be appreciated that the packed bed reactor has been shown three times in both Figures 1 and 3 and each embodiment is conducting a different reaction. However, as will be explained below, each packed bed reactor which will be used to carry out each of the three steps sequentially. Accordingly, the packed bed reactor can be operated dynamically. As shown on the left in Figure 1, the first reaction conducted may be an oxidation reaction. In this reaction, an oxygen containing gas (e.g. air) is fed through a compressor (COMP-20) and a heat exchanger (HE-21). The oxygen containing gas is pre-heated to an inlet temperature of at least 4OO°C and is fed into the packed bed reactor where it causes the oxygen carrier to oxidise. The reaction may be written as: MeOx-i + 1 / 2 02MeOx(Ri)

[0137] It may be appreciated that Me is a metal. When x is 1, the above reaction will be the conversion of a metal to a metal oxide. The above oxidation reaction is exothermic. Accordingly, while the inlet temperature may only be about 400 °C, the temperature within the packed bed reactor will rise above this such that the reaction will occur at a temperature of 8oo-9OO°C.

[0138] An oxygen-depleted gas will be obtained, and will mainly contain N2. This gas can be fed through the heat exchanger (HE-21), to pre-heat the oxygen containing gas, and then expanded to produce some electricity.

[0139] As shown in the middle of Figure 1, the next reaction which may be carried out is a reduction reaction. The reaction will comprise using waste gas, such as blast furnace gases, waste gases from bio-based processes, offgas from refineries and chemical process plants, and / or waste streams from the bio-diesel plant (Error! Reference source not found.). The waste gas is first cleaned from acid gas, ashes and sulphur compounds and then compressed to a required process pressure using a compressor (COMP-10) and preheated to 150-250 °C using a heat exchanger (HE- 11). Depending on the gas composition, steam can be used to reduce the risk of carbon deposition, mixed with the waste gas. The combined waste gas and steam may then be preheated in a heat exchanger (HE-12) to an inlet temperature of at least 450 °C.

[0140] As noted above, the packed bed reactor has been heated to a temperature of greater than 800 °C due to the oxidation reaction. Accordingly, the reduction will occur at a temperature > 800 °C. Components of the waste gas will reduce the metal oxide in the packed bed reactor and will themselves be oxidised. In particular, all hydrocarbons, CO and H2components will be converted into C02and H20, therefore the outlet stream is a composition of H20, C02, and inert gases (e.g. N2). The reduction reactions which occur in this step may be written as:

[0141] H2+ MeOxMeOx-i +H20 (R4) It may be appreciated that hydrocarbons other than methane, if present in the waste gas, may similarly be combusted in this step and will produce carbon dioxide and water.

[0142] The above reduction reactions are thermally neutral and may be conducted at a temperature of between 800 and 900 °C.

[0143] The outlet stream is cooled to ambient temperature, water is condensed and separated.

[0144] The stream can be sent to a C02selective membrane which operates with or without sweep gas (such as H2) to separate C02up to >95%. The separated C02is recycled in the system as discussed below.

[0145] If desirable, the C02obtained from the reduction reaction can be supplemented with further C02from an external source, e.g. a pipeline or other industrial process. C02is compressed to the required pressure using a compressor (COMP-31).

[0146] Hydrogen gas, which may be generated from water electrolysis, is also compressed to the required process pressure (using COMP-30) and mixed with C02stream. The stream is pre-heated to an inlet temperature of at least 350 °C. The gases are converted into CO and H2in the reactor operated in RWGS in a temperature range of 650- 1000

[0147] °C. This reaction is facilitated by the presence of the reduced oxygen carrier which acts as a catalyst. The outlet gas is cooled to a lower temperature (<350 °C) in a HE-32 and the syngas generated can be used for further synthesis or conversion. The RWGS reaction may be written as:

[0148] H2+ CO CO +H20 (R5)

[0149] The above reduction reactions is endothermic. It may be appreciated that heat generated in the exothermic oxidation reaction (Ri) will be used during the endothermic RWGS reaction (R5). The syngas generated from the reverse water gas shift is a combination of hydrogen, carbon monoxide and carbon dioxide that could be used for the Fischer-Tropsch process to produce desirable products, such as renewable fuels (including aviation and maritime fuels) and olefins.

[0150] In some embodiments, the system may comprise three or more packed bed reactors.

[0151] This is shown in Figure 4 where valves control the input gases fed into three packed bed reactors. The valves can be switched to sequentially switch the input gas which is fed into a reactor, and thereby change the reaction which is occurring therein. Accordingly, each of the oxidation reaction, reduction reactions and RWGS reaction may be conducted continuously, but the packed bed reactor each reaction occurs in will change with time. Example 2 - Experimental Validation

[0152] Methodology

[0153] The packed-bed reactors are dynamically operated to carry out the three main reaction stages. In this example, Cu has been used as the oxygen carrier (OC) therefore the reaction performed are Cu-oxidation, CuO reduction and RWGS (Error! Reference source not found.). The main chemical reactions that take place in the CL-RWGS process are tabulated in Table 1.

[0154] Table 1: Chemical reactions considered in the CL-RWGS process Before the CL-RWGS experimentation, the Cu-based material was tested under 600 °C temperature and 1 bar pressure conditions for over 10 continuous redox cycles. After the redox cycles, the material was tested for RWGS activities under various temperatures (650 - 900 °C), pressure (1 - 8 bar) and feed composition (H2:C02molar ratio of 0.2:1 to 2.0:1). The CL-RWGS experiments are conducted in a lab-scale packed- bed reactor setup using various conditions of temperature (500 - 600 °C), pressure (1 - 5 bar), feed flowrate (10 - 16 NLPM) and inlet feed compositions.

[0155] The experimental campaign of the CL-RWGS process was carried out in a laboratory located at the University of Manchester. The overall packed-bed reactor setup consisted of a dry gas feeding system and gas analysis equipment such as a CO analyser and a mass spectrometer. In addition to the central supply of gases (H2, N2, He, CH4and air), the gas feeding system consisted of in-house cylinders of CO and C02. The jacket- heated packed-bed reactor, manufactured by Array industries B. V, had 1050 mm length and 35 mm inside diameter. 250 g of Cu-based OC had been packed inside the reactor, 400 mm bed length, with the top and bottom part of the reactor fully packed with inert material (A12O3). Inert material at the top and bottom of the reactor is used to make sure that OC is firmly packed inside the reactor throughout the CL-RWGS experimental campaign.

[0156] A schematic of the experimental setup is shown in Figure 5.

[0157] A comprehensive experimental campaign was carried out, as detailed in Table 2. Table 2: The lab-scale conditions used during the CL-RWGS process

[0158] Results

[0159] Figure 6 shows the effect of temperature and H2 / C02molar ratio in the feed over the H2 / C0 and C0 / C02molar ratio obtained in the product gases. The experimental campaign demonstrated that the H2 / CO ratio depends on the operating temperature and H2 / C02feeding ratio. Figure 6(a) shows that a H2 / C0 molar ratio of close to 2 can be obtained, which is beneficial as this would be required for the synthesis of liquid fuels via Fischer-Tropsch. To further explore the effect of temperature on the H2 / C0 molar ratio, a wide range of temperatures (650 - 900 °C) is studied in Figure 7 and results are compared with the equilibrium values obtained through Gibbs reactor simulation using Aspen PLUS® software which shows how close is the conversion to chemical equilibrium despite the material tested not being optimised. The experimental results show that a H2 / C02molar ratio in the range of 1.0 - 1.3 and an operating temperature of 700 - 800 °C is favourable for a H2 / C0 molar ratio close to 2.0.

[0160] Using a H2 / C02molar ratio of 1.3 in the feed, the effect of pressure (1 - 8 bar) over the H2 / C0 molar ratio in the product was studied, and the results are provided in Figure 8. It can be seen that higher pressure increases the H2 / C0 molar ratio in the product but the H2 / C0 molar ratio decreases as temperature increases from 650 to 900 °C.

[0161] In practice, the actual preferred pressure may be dictated by the upstream and downstream process to minimize the cost of energy compression. The pressure can be selected to minimise the cost, and other variables (e.g. temperature) may be modified to provide the desired product.

[0162] Example 3: Complete cycle of CL-RWGS

[0163] A complete cycle of CL-RWGS using Cu-based OC was performed. The conditions used for the Cu-oxidation, CuO reduction, RWGS and purge stages are provided in Table 3. Table 3: The inlet conditions for the complete cycle of CL-RWGS (furnace temperature at 600 °C and pressure at 1 bar)

[0164] As the pressure and temperature have a significant effect on the CL-RWGS process in terms of syngas production, the complete cycle of CL-RWGS has been performed at 2 different pressure (1 and 5 bar) and 3 different temperatures (5OO°C, 55O°C and 6oo°C) conditions. The gas breakthrough and the recorded solid temperature profiles are presented in Figure 9. The oxidation step caused a rise of max 150 °C in the bed. The supply of air was turned off at 280 s before 02breakthrough. Soon after the oxidation step, the reactor was purged for 140 s using 4 NLPM of pure N2to remove the 02from the reactor before starting the next reaction stage. During the reduction and RWGS stage, a gas mixture having an H2 / C02molar ratio of 1.3 was fed in the reactor for 320 s. In the initial phase of this reaction stage, H2in the feed reduced the CuO.

[0165] After 170 s of this stage, once the reduction was finished, H2and C02react through the RWGS reaction and produce syngas (H2 / C0 molar ratio = 3.1). The temperature profile in Error! Reference source not found, (b) shows a sudden rise in temperature during the reduction and then a drop as RWGS started.

[0166] Ten complete cycles of the CL-RWGS process were carried out at 550 °C, 1 bar pressure and a H2 / C02molar ratio of 1.3 in the feed, and the results are shown in Figure 10. The results demonstrate very good repeatability of the process and stability.

[0167] Example 4: Process Integration - syngas to liquid fuels

[0168] The proposed invention can be integrated with other processes to generated value- added products. For instance, the syngas may be converted into liquid fuels for transport fuels and / or olefins using a Fischer-Tropsch (FT) process. An apparatus which could conduct this process is shown in Figure 11. Syngas, produced in the RWGS reaction, as described above, is cooled to 200-400 °C and fed into a FT reactor which converts CO and H2into hydrocarbons. The syncrude generated from the reactor is split into three main streams: light gases, liquid products and long chain hydrocarbons. The light gases are partly recycled by feeding a portion back into the FT inlet to increase the overall CO conversion. The remainder of the light gases is sent to the reactor operated for reduction in the chemical looping system described above. The liquid products are sent to a fractionation unit. Finally, the long chain hydrocarbons are sent to a hydrocracker process to be converted into suitable products, which may then also be sent to the fractionation unit.

[0169] Example : Process Integration - high energy recovery

[0170] Another option for process integration would be to use and valorise the waste stream from the process, this is shown in Figure 12. In this case, the membrane is operated with hydrogen as a sweep gas. Sweep gas can be used at pressure of 1 to 20 bar. The hydrogen stream is the same required for the RWGS conversion.

[0171] Part of the hydrogen permeates to the retentate side due to the positive driving force dictated by the positive hydrogen partial pressure difference from permeate and retentate side. Therefore, part of the hydrogen is available in the retentate stream which would contain nitrogen (>80% in vol.), hydrogen (<20%) and C02(1-10%), the exact composition would depend on the purification conditions. The retentate stream can be used as fuel for a recuperative gas turbine process which could provide electricity to the overall plant. Example 6: Process Integration - synthesis of ammonia

[0172] Alternatively, in order to increase the flexibility of the plant, the retentate stream from the membrane could be adjusted with additional hydrogen from the electrolyser in order to provide a gas stream with a hydrogen-to-nitrogen molar ratio of 3, which is ideal for the NH3synthesis process using the Haber-Bosch technology, as shown in Figure 13. Such a configuration would require an increase of the electrolyser capacity up to an additional 150% to convert the remaining nitrogen at the retentate side into ammonia.

[0173] Example 7: Additional experiments The CL- RWGS has also been tested with Ni-based catalyst and oxygen carrier at different operating conditions. Table 4: Different operation conditions used

[0174] The results are shown in Figure 14 and are consistent with those reported for Cu-based materials. In particular, the H2 / CO ratio can be controlled by the temperature and CO2 / H2 feed ratio.

[0175] Next full cycles were carried out at 6oo°C with oxidation using 10% 02, reduction using 20% H2and RWGS using 10% C02and 20% H2at both 1 and 5 bar, and the results are shown in Figure 15.

Claims

Claims1. A method of producing syngas, the method comprising: feeding a first input gas into a reactor, wherein the first input gas comprises oxygen and the reactor comprises an oxygen carrier material, and thereby causing the oxygen carrier material to oxidise; feeding a second input gas into the reactor, wherein the second input gas comprises carbon monoxide and / or a fuel, and thereby causing the oxygen carrier material to be reduced and the carbon monoxide and / or fuel to oxidise to produce a second output gas; purifying the second output gas to obtain a purified gas with a high concentration of carbon dioxide; and feeding a third input gas into the reactor, wherein the third input gas comprises the purified gas and a hydrogen gas stream, and thereby causing syngas to be produced.

2. The method of claim 1, wherein the method comprises heating the first input gas to a first elevated input temperature prior to feeding the first input gas into the reactor, and the first elevated input temperature is at least 5O°C, at least ioo°C, at least 15O°C, at least 200°C, at least 25O°C, at least 3OO°C, at least 35O°C or at least 375°C.

3. The method of claim 1 or claim 2, wherein the method comprises stopping feeding the first input gas into the reactor prior to feeding the second input gas into the reactor.

4. The method according to any preceding claim, wherein the second input gas is or comprises a waste gas, preferably wherein the waste gas is or comprises a waste gas from a blast furnace, a waste gas from a bio-based process, an offgas from a refinery or chemical process plant and / or a waste gas from a bio-diesel plant.

5. The method according to any preceding claim, wherein the second input gas comprises between 1 and 80 vol%, between 5 and 70 vol%, between 7.5 and 60 vol%, between 10 and 50 vol%, between 12 and 40 vol%, between 13 and 35 vol%, between 14 and 30 vol% carbon monoxide, between 15 and 27.5 vol% carbon monoxide, between 16 and 25 vol% carbon monoxide or between 17.5 and 22.5 vol% carbon monoxide.

6. The method according to any preceding claim, wherein the second input gas comprises a fuel, wherein the fuel is or comprises a hydrocarbon.

7. The method according to any preceding claim, wherein the second input gas comprises between 5 and 95 vol%, between 10 and 90 vol%, between 20 and 80 vol%, between 30 and 70 vol%, between 35 and 60 vol%, between 40 and 55 vol% or between 45 and 50 vol% nitrogen.

8. The method according to any preceding claim, wherein the method comprises heating the second input gas to a second elevated input temperature prior to feeding the second input gas into the reactor, and the second elevated input temperature is at least 5O°C, preferably at least ioo°C, at least 15O°C or at least 200°C, and more preferably at least 25O°C, at least 3OO°C, at least 35O°C, at least 4OO°C or at least 45O°C.

9. The method according to any preceding claim, wherein purifying the second output gas comprises separating water out of the second output gas.

10. The method according to any preceding claim, wherein purifying the second output gas comprises using a carbon dioxide selective membrane to obtain the purified gas.

11. The method according to any preceding claim, wherein the method comprises stopping feeding the second input gas into the reactor prior to feeding the third input gas into the reactor.

12. The method according to any preceding claim, wherein the method comprises combining the purified gas and the hydrogen gas stream, and optionally a further carbon dioxide gas stream, to provide the third input gas, such that the third input gas has a molar ratio of hydrogen to carbon dioxide of between 0.1:1 and 5:1, between 0.3:1 and 3:1, between 0.5:1 and 2.5:1, between 0.6:1 and 2:1, between 0.8:1 and 1.5:1 or between 1:1 and 1.3:1.

13. The method according to any preceding claim, wherein the method comprises heating the third input gas to a third elevated input temperature prior to feeding the third input gas into the reactor, and the third elevated input temperature is at least50°C, at least ioo°C, at least 15O°C, at least 200°C, at least 25O°C, at least 300°C or at least 325°C.

14. The method according to any preceding claim, wherein the method comprises: in a first step: feeding a first input gas into a first reactor, wherein the first input gas comprises oxygen and the reactor comprises an oxygen carrier material, and thereby causing the oxygen carrier material in the first reactor to oxidise; simultaneously feeding a second input gas into a second reactor, wherein the second reactor comprises an oxygen carrier material and the second input gas comprises carbon monoxide and / or a fuel, and thereby causing the oxygen carrier material to be reduced and the carbon monoxide and / or fuel to oxidise to produce a second output gas in the second reactor; purifying the second output gas to obtain a purified gas with a high concentration of carbon dioxide; and simultaneously feeding a third input gas into a third reactor, wherein the third reactor comprises an oxygen carrier material and the third input gas comprises the purified gas and a hydrogen gas stream, and thereby causing syngas to be produced in the third reactor; and subsequently switching the feeds of the input gases such that a second step comprises: feeding the first input gas into the third reactor, and thereby causing the oxygen carrier material in the third reactor to oxidise; simultaneously feeding the second input gas into the first reactor, and thereby causing the oxygen carrier material to be reduced and the carbon monoxide and / or fuel to oxidise to produce the second output gas in the first reactor; purifying the second output gas to obtain a purified gas with a high concentration of carbon dioxide; and simultaneously feeding the third input gas into the second reactor, and thereby causing syngas to be produced in the second reactor; and subsequently switching the feeds of the input gases such that a third step comprises: feeding the first input gas into the second reactor, and thereby causing the oxygen carrier material in the second reactor to oxidise;simultaneously feeding the second input gas into the third reactor, and thereby causing the oxygen carrier material to be reduced and the carbon monoxide and / or fuel to oxidise to produce the second output gas in the third reactor; purifying the second output gas to obtain a purified gas with a high concentration of carbon dioxide; and simultaneously feeding the third input gas into the first reactor, and thereby causing syngas to be produced in the first reactor.

15. A method for producing a liquid fuel, the method comprising: conducting the method of any one of the preceding claims to produce a syngas; and converting the syngas into a liquid fuel.

16. An apparatus for producing a syngas, the apparatus comprising: a reactor; an oxygen carrier material disposed in the reactor; an input valve, configured to selectively feed an input gas into the reactor; a purifier, configured to purifying an output gas to obtain a purified gas with a high concentration of carbon dioxide; an output valve configured to selectively feed a second output gas from the reactor to the purifier; and a purified conduit, extending between the purifier and the input valve, and configured to feed the purified gas from the purifier to the input valve.

17. The apparatus of claim 16, wherein the purifier comprise a carbon dioxide selective membrane.

18. The apparatus of claim 16 or claim 17, wherein the input valve is configured to selectively feed first, second and third input gases into the reactor or the apparatus comprises first, second and third input valves, wherein the first input valve is configured to selectively feed a first input gas into the reactor, the second input valve is configured to feed a second input gas into the reactor and the third input valve is configured to selectively feed a third input gas into the reactor.19- The apparatus according to any one of claims 16 to 18, wherein the output valve is configured to selectively control where the first, second and third output gases are fed after being removed from the reactor, such that the output valve is configured to selectively feed the first output gas from the reactor to a first output gas conduit or vent the first output gas, selectively feed the second output gas from the reactor to the purifier and selectively feed the third output gas from the reactor to a third output gas conduit or the apparatus comprises first, second and third output valves, wherein the first output valve is configured to selectively feed a first output gas to a first output gas conduit or vent the first output gas, the second output valve is configured to selectively feed a second output gas to the purifier and the third output valve is configured to selectively feed a third output gas to a third output gas conduit.

20. The apparatus according to any one of claims 16 to 19, wherein the apparatus comprises: first, second and third reactors; an oxygen carrier material disposed in each of the first, second and third reactors; first, second and third input valves configured to selectively feed first, second and third input gases into the first, second and third reactors; a purifier, configured to purifying an output gas to obtain a purified gas with a high concentration of carbon dioxide; first, second and third output valves, wherein at least one of the first, second and third output valves is configured to selectively feed a second output gases from the reactor to the purifier; and a purified conduit, extending between the purifier and at least one of the first, second and third input valves, and configured to feed the purified gas from the purifier to the at least one of the first, second and third input valves.

Images