Purification of co2-containing feed gas

Abstract

The present invention relates to a process for purifying a CO2-rich gas feed, in particular for removing sulfur-containing impurities and optionally oxygen.

Description

Technical Field

[0001] This invention relates to a method for purifying CO2-rich gas feed, particularly for removing sulfur-containing impurities and optional oxygen (O2). Background Technology

[0002] Carbon dioxide (CO2) is commercially available in different grades. Typically, "food grade" or "beverage grade" CO2 has a purity of 99.9%. However, for processes involving the catalytic conversion of CO2 into other chemical products (e.g., electro-to-X), impurities in the CO2 stream (e.g., sulfur compounds) can poison the synthesis catalyst, even at concentrations of 0.00001% (100 ppbV) or even lower. Oxygen (O2) rarely poisons catalysts, but at higher concentrations (e.g., above 100 ppm), its ability to oxidize catalyst materials can cause structural damage, leading to a decline in mechanical or catalytic performance.

[0003] The CO2 source is highly pure, but it has been found that further purification is needed to avoid catalyst poisoning or degradation of downstream synthesis catalysts.

[0004] As is well known, sulfur compounds are catalyst poisons, reacting with the active materials on the catalyst and causing catalyst deactivation. For some catalysts, oxygen (O2) is also a key factor leading to catalyst degradation. For example, Cu-based methanol catalysts are easily oxidized by oxygen. Therefore, it is necessary to remove the high concentration of oxygen present in the CO2 (or H2) feed gas in the methanol plant upstream of the methanol catalyst.

[0005] It has been found that catalyst / adsorbent systems developed for removing sulfur impurities from CO2 are also sensitive to relatively high oxygen concentrations, and a solution has been developed to remove O2 from CO2 gas before it enters the sulfur removal process.

[0006] Systems and methods for purifying CO2 streams are known, for example, from EP2457636, CN112999843, US2007028764, US200702877, US2022333015 and CN112957872. Summary of the Invention

[0007] The inventors have discovered that sulfur purification of the CO2 feed is necessary, which can be achieved by adsorption onto a metal-promoted protective material after the addition of 2% H2, resulting in a subsequent CO2 stream containing <10 ppbV sulfur. The study also found that any oxygen in the CO2 feed affects the sulfur capacity and mechanical integrity of the protective material.

[0008] Therefore, a first aspect of the present invention relates to a method for purifying a CO2-rich gas feed, said CO2-rich gas feed comprising at least 80 wt% CO2 and one or more sulfur-containing impurities; wherein said method comprises the following steps: - Passing a CO2-rich gas feed along with a hydrogen-rich feed through a protective material, and adsorbing one or more sulfur-containing compounds onto the protective material to provide a purified CO2-rich gas flow.

[0009] The present invention also provides a method for producing a synthesis gas stream, the method comprising the above-described method, and further comprising: - Provide a purified CO2-rich gas stream from at least a portion of the methods described above; - Provide a second hydrogen-rich feed, which may optionally be obtained from the water electrolysis process in one or more electrolysis units; - The purified CO2-rich gas stream in this section is reacted with the second hydrogen-rich feed to provide at least one synthesis gas stream.

[0010] The present invention also provides a method for producing a synthetic fuel stream, the method comprising the above-described method, and further comprising the step of converting the at least one synthetic gas stream into at least one synthetic fuel stream, wherein the synthetic fuel stream is preferably a MeOH (methanol) stream, a DME (dimethyl ether) stream, or a synthetic fuel stream, wherein the synthetic fuel may be aviation fuel, gasoline, diesel, or the like.

[0011] Other aspects will be set forth in the following description, drawings and claims.

[0012] Brief description of the attached figures

[0013] Figure 1 A simplified layout of one embodiment of the method of the present invention is shown.

[0014] Figure 2 The layout for producing the synthetic gas flow is shown.

[0015] Figure 3 Another layout for the CO2 gas purification process is shown.

[0016] Figure 4 Data from Example II is shown. Invention Details

[0018] Unless otherwise specified, any given percentage of gas content is based on volume as %, ppm (parts per million) or ppb (parts per billion). All feeds are preheated upon request. Unless otherwise specified, concentrations are on a dry basis, i.e., without regard to any moisture present.

[0019] A purified CO2 stream is defined as the effluent stream from a CO2 purification process, wherein at least 95% of sulfur-containing impurities in the feed are removed, or the total sulfur-containing impurity content in the purified CO2 stream is less than 500 ppb (parts per billion by volume), preferably less than 100 ppb, and most preferably less than 50 ppb.

[0020] The total sulfur content in the purified CO2 stream should be understood as sulfur equivalent, that is, 100 ppb SO2 corresponds to 100 ppb sulfur, while 100 ppb CS2 corresponds to 200 ppb sulfur.

[0021] Similarly, a purified CO2 stream is defined as the effluent stream from a CO2 purification process, wherein at least 95% of the oxygen in the feed is removed, or the O2 concentration in the purified CO2 stream is less than 200 ppm, preferably less than 100 ppm, and most preferably less than 50 ppm.

[0022] Syngas, or synthesis gas, is a gaseous mixture containing hydrogen, carbon monoxide, carbon dioxide, water (usually as steam), and methane. It is called syngas / synthetic gas because it is the feedstock for downstream catalytic synthesis, ultimately producing the desired product. In some applications, the aforementioned purified downstream feedstock can be mixed with hydrogen as a syngas, for example, for methanol synthesis; in other applications, the purified gas, after being mixed with hydrogen and optionally steam, may need to be converted in a reverse water gas shift reactor (RWGS) or a combination of RWGS and methanation reactor to form the final syngas used to synthesize the final product.

[0023] The proposed solution ensures that feed gases converted downstream for synthesis gases and for the synthesis of chemicals such as MeOH, dimethyl ether, FT (Fischer Tropsch) synthetic fuels, TIGAS-based gasoline, etc., will not cause sulfur or oxygen poisoning issues to downstream synthesis catalysts. This will ensure continuous operation and allow catalyst lifetime to reach the expected levels for industrial catalysts.

[0024] Therefore, in a first aspect, a method for purifying CO2-rich gas feed is provided.

[0025] The CO-rich gas feed provided to the method preferably contains at least 90 wt% CO2, for example at least 95 wt% CO2, for example at least 99.0 wt% CO2, preferably at least 99.5 wt% CO2, and more preferably at least 99.9 wt% CO2. Therefore, the CO2-rich gas feed already possesses high purity prior to the method of the present invention.

[0026] Suitable, the CO2-rich gas feedstock is derived from a renewable source, such as: - Combustion or gasification of lignocellulosic biomass, such as wood products, algae, grass, forestry waste and / or agricultural residues; - Combustion or gasification of municipal waste, particularly its organic component, wherein municipal waste is defined as raw material containing materials of publicly discarded articles, such as mixed municipal waste as given in Annex IX, Part A of EU Directive 2018 / 2001 (RED II); - Microbial transformation of nitrogen-rich renewable feedstocks (such as feces or sewage sludge); - Hydrocarbon-rich (sugar) feed streams, such as the fermentation of corn, sugarcane, and sugar beets.

[0027] CO2-rich gas feedstocks can also be obtained through direct air capture processes, metallurgical processes, cement production, or fossil fuel combustion.

[0028] The CO2 concentration in most of the aforementioned airflows may often be too low for further chemical processing, thus requiring a concentration step to increase the CO2 concentration to the desired value as described above.

[0029] The CO2-rich gas feed contains one or more sulfur-containing impurities. These impurities can be selected from organic sulfur compounds, such as thiols, sulfides, disulfides, sulfones, sulfoxides and thioketones, CS2, COS, SO3, SO2 and H2S, preferably H2S and SO2, and most preferably SO2. The total SO2 content in the CO2-rich gas feed is 0.1-50 ppm SO2, for example 0.2-10 ppm SO2, for example 1-10 ppm SO2, for example 0.5-5 ppm SO2, for example 1-5 ppm SO2.

[0030] Water may also be present in the CO2-rich gas feed. However, high concentrations of water can limit / inhibit the absorption of sulfur compounds by the protective material, and limiting the water concentration will help the protective system operate more efficiently. Therefore, it is preferable that the total H2O content in the combined feed, after mixing the CO2-rich gas feed and the hydrogen-rich feed, does not exceed 10 vol%, preferably not more than 5.0 vol%, and more preferably not more than 1.0 vol%, for example, about 0.5 vol%.

[0031] In some cases, CO2-rich gas feeds may contain oxygen (O2). Oxygen can also contaminate, poison, or degrade downstream catalysts and protective materials; therefore, any oxygen in CO2-rich gas feeds should generally be reduced or eliminated. The total O2 content in CO2-rich gas feeds is typically 50-10,000 ppm O2, for example, 50-5,000 ppm O2, or 100-3,000 ppm VO2.

[0032] Typically, the method includes the following steps: passing a CO2-rich gas feed along with a hydrogen-rich feed through a protective material, and adsorbing one or more sulfur-containing compounds onto the protective material to provide a purified CO2-rich gas flow.

[0033] In one embodiment, the CO2-rich gas feed also contains oxygen (O2), and the method includes the following steps: - The CO2-rich gas feed and the hydrogen-rich gas feed are passed together through a catalyst with oxygen hydrogenation activity to reduce the oxygen in the CO2 / H2 gas mixture, thereby providing a first CO2-rich gas flow. Then, a step is performed in which CO2-rich gas is fed through a protective material to adsorb one or more sulfur-containing impurities in order to provide a purified CO2-rich gas stream.

[0034] The CO2-rich gas feed to be purified can be mixed with a hydrogen-rich feed first. The hydrogen-rich feed can act as a reducing agent for one or more sulfur-containing impurities in the CO2-rich gas feed, and optionally as a reducing agent for oxygen. The hydrogen-rich feed entering the process contains at least 90 wt% hydrogen, for example, at least 95 wt% hydrogen, or at least 98 wt% hydrogen.

[0035] In one embodiment, hydrogen is appropriately added so that after mixing the CO2-rich gas feed and the hydrogen-rich feed, the total H2 content in the combined feed is 0.2-10 vol%, for example, 0.5-3 vol%. The advantage of this embodiment is that the addition of hydrogen can be controlled, thereby limiting undesirable side reactions, such as the formation of methanol. The amount of hydrogen added should always be sufficient to ensure an excess of H2 in the product gas leaving the protective material.

[0036] In one embodiment, hydrogen is appropriately added so that, after mixing, the H2:O2 molar ratio in the combined feed of the CO2-rich gas feed and the hydrogen-rich feed is greater than 2, and the purified CO2 leaving the CO2 purification system contains 0.2-10 vol% H2, for example, 0.5-3 vol% H2. The advantage of this embodiment is that the addition of H2 can be controlled, thereby limiting undesirable side reactions (such as methanol formation), while still having sufficient excess H2 to ensure a high degree of hydrogenation of oxygen and sulfur impurities. Furthermore, in this embodiment, the total gas flow rate is kept to a minimum, thereby providing the smallest possible reactor and equipment size.

[0037] In another embodiment of the invention, hydrogen is added to a CO2-rich gas feed in an amount corresponding to the feed composition of downstream processes used to produce syngas, methanol, synthetic fuels, and other chemical products. For example, for methanol production, the feed composition of a methanol process is approximately 12% w / w H2 and 88% w / w CO2. This is equivalent to 3 moles of H2 for every mole of CO2. An advantage of this embodiment is that H2 and CO2 can be mixed and preferably compressed before CO2 purification. The CO2 purification process can be located downstream of the final compression step or between intermediate compression steps, depending on cost, water concentration, the risk of carbonate formation to protective materials, and the risk of generating undesirable byproducts such as water and methanol. Another advantage of this embodiment is that any O2 present in the H2-rich feed will also be hydrogenated. The H2 produced by water electrolysis may contain varying amounts of O2, depending on the operating conditions of the electrolyzer.

[0038] One or more sulfur-containing compounds adsorbed onto the protective material are typically selected from COS, SO2, and H2S, with SO2 being preferred. The protective material exhibits suitable adsorption activity for both SO2 and H2S, with Cu-Zn-Al protective materials being preferred. In the presence of H2, this protective material can catalytically reduce SO2 in a CO2-rich feed to H2S, with H2S showing a much higher adsorption efficiency on the protective material than SO2. This protective material can also cause oxygen and hydrogen in the CO2 feed stream to react and generate water.

[0039] This process provides a purified CO2-rich gas stream. This purified CO2-rich gas stream typically contains: - Sulfur concentration less than 500 ppb, preferably less than 100 ppb, more preferably less than 50 ppb, and even more preferably less than 25 ppb. - Less than 200 ppmV O2, less than 100 ppmV O2, less than 50 ppmV O2. The protective material used in the method of the present invention is suitably located within a reactor vessel arranged to receive a CO2-rich gas feed and a hydrogen-rich feed in the form of an optional mixture.

[0040] The preferred chemical composition of the protective material is 25-60% w / w Cu, 15-70% w / w Zn, and optionally 2-10% w / w Al. Small amounts of K and C may also be included. These elements can be in reduced or oxidized states.

[0041] CO2 purification processes typically operate within a pressure range of 1-100 bar, preferably 1-50 bar, depending on the pressure of the CO2 feed stream and the pressure of the downstream conversion process.

[0042] To achieve the optimal balance between high catalytic / adsorption efficiency and low carbonate formation tendency, as well as the tendency for undesirable side reactions (such as water and methanol formation), CO2 purification processes are typically operated in a temperature range of 120–250°C. Pressure is typically in the range of 1–90 bar.

[0043] In one aspect, more than 95% of one or more sulfur-containing impurities are retained on the protective material, or the total concentration of sulfur-containing impurities in the purified CO2-rich gas stream is < 500 ppb, for example < 100 ppb, for example < 50 ppb.

[0044] As described above, the purified CO2-rich gas stream is sufficiently pure, thereby significantly reducing catalyst poisoning in downstream processes. Therefore, this invention provides a method for producing a synthesis gas stream, the method comprising the above-described method, and further comprising: - Provide at least a portion of the purified CO2-rich gas stream from the method described herein; - Provide a second hydrogen-rich feed, which may optionally be obtained from a water electrolysis process in one or more electrolysis units; - The purified CO2-rich gas feed of this section reacts with the second hydrogen-rich feed to provide at least one synthesis gas stream.

[0045] In this method, the step of reacting the purified CO2-rich feed stream with the second hydrogen-rich feed stream to provide at least one synthesis gas stream can be carried out in the presence of a catalyst with reverse water-gas shift activity.

[0046] Integrated processes can also be employed to combine CO2 purification, syngas production, and subsequent downstream synthesis processes. Therefore, a method for producing a synthetic fuel stream is provided, comprising providing at least one syngas stream (as described herein), and further comprising the step of converting the at least one syngas stream into at least one synthetic fuel stream, preferably a MeOH stream, a DME stream, or a synthetic fuel stream, wherein the synthetic fuel is preferably aviation fuel, gasoline, or diesel fuel. On one hand, the process for converting the at least one syngas stream into at least one synthetic fuel stream is the Fischer-Tropsch process, which provides the synthetic fuel stream. On the other hand, the process for converting the at least one syngas stream into at least one synthetic fuel stream is the TIGAS process, which provides the synthetic fuel stream. Detailed Implementation

[0047] Figure 1 A simplified layout of one embodiment of the method of the present invention is shown. A CO2-rich gas feed 1 is mixed with a hydrogen-rich gas feed 2 and passes through a protective material 10 in a reactor vessel 100. Sulfur-containing compounds are adsorbed onto the protective material 10, and a purified CO2-rich gas stream 50 is output.

[0048] Figure 2 The layout of the production synthesis gas flow is shown. The reactor vessel 100, CO2-rich gas feed 1, hydrogen-rich gas feed 2, and purified CO2-rich gas flow 50 are all arranged according to... Figure 1 As shown. Subsequently, the second hydrogen-rich feed 202 reacts with the purified CO2-rich feed 50 in the syngas section 300 to generate at least one syngas stream 301.

[0049] Figure 3 An embodiment of a CO2 gas purification process layout is shown. A CO2 gas feed (1) containing O2 and one or more sulfur-containing impurities is mixed with a certain amount of H2-rich gas (2). The mixed gas is sent to a compressor (5) and pressurized. The high-pressure feed gas (6) is then preheated in a heat exchanger (7), and the heated feed gas (9) is sent to an oxygen hydrogenation reactor (11) containing an oxygen hydrogenation catalyst (12) to hydrogenate O2 into H2O. The substantially O2-free CO2 gas stream (17) is then cooled in a heat exchanger (18) to bring the feed gas (20) entering the desulfurization reactor (22) to an optimal temperature. The reactor is equipped with protective material (10) for removing sulfur impurities. The tail gas from the desulfurization reactor (26) is substantially free of oxygen and sulfur impurities and can be further processed into syngas and other products.

[0050] Example

[0051] Experiments were conducted under isothermal conditions in a laboratory fixed-bed reactor to test the SO2 removal efficiency of the protective material. The fixed-bed reactor was placed in an electrically heated oven and heated to the required operating temperature. Two internal thermocouples measured the inlet and outlet temperatures of the catalytic bed. The oven was equipped with external thermocouples to control the temperature zones within the oven. These temperature zones were controlled via internal thermocouple readings to achieve isothermal reaction conditions within the fixed bed.

[0052] Protective material is placed in a coating of SilcoNert 2000 TM The stainless steel reactor is mounted on a grid, and the reactor is adjusted and aligned to be centered within the electrically heated oven. Feed gases are mixed from gas cylinders via a mass flow controller to control the individual gas feeds. These gases include nitrogen (N2), hydrogen (H2), carbon dioxide (CO2), and sulfur dioxide (SO2 in CH4) at 15 or 100 ppmV in methane. Liquid water is pumped through an evaporator and mixed with the feed gases upstream of the fixed-bed reactor.

[0053] The protective material used is a co-precipitated Cu / ZnO / alumina-based protective material. In a single test, when the protective material can be divided into fractions (beds), the total weight of the protective material and the number of fractions / beds are given. Each fraction is typically the same size. The protective material was pulverized and sieved before being loaded into the laboratory reactor, with particle sizes ranging from 600 μm to 1000 μm of the original material size to achieve optimal dimensions. Before measuring the removal of SO2 from the CO2 feed gas, the protective material was reduced in N2 containing 2% H2 at 220°C and 3 barg.

[0054] Table 1 lists the different tests conducted with the addition of SO2 to the CO2 feed gas, and the outlet analysis given are the results obtained after 200 hours of continuous SO2 addition.

[0055] Table 1

[0056] Sulfur feed and outlet gas concentrations were measured using an Agilent 7890A GC system equipped with an OI 5380 pulsed flame photometric detector (PFPD). Except for tests 1 and 2, both experiments used an Agilent 8355 S column equipped with an S chemiluminescence detector, which has a higher detection limit of 100 ppbV. For tests #5b and 6, the SO2 outlet analysis results in Table 1 are based on sulfur balance estimates, as SO2 was not detected below the SO2 detection limit of 50 ppbV. These results are shown in italics.

[0057] Example (II)

[0058] O2 Xtract from Haldor Topsoe TM The O2 hydrogenation activity of a hydrogenation catalyst containing Pd and Pt as active components was investigated. The hydrogenation activity was measured in a CO2 feed gas containing 2.5 vol% H2, 2,000 ppm O2, and 0 or 10 ppm SO2. The catalyst space velocity was 180,000 Nm. 3 / h / m 3 The temperature varies within the range of 50-350°C. O2 concentrations at the catalyst inlet and outlet are measured using a dedicated CO2 sensor, and the O2 hydrogenation conversion is calculated based on these concentrations. The relationship between conversion and catalyst temperature is as follows: Figure 4 As shown. Clearly, the hydrogenation catalyst exhibits very high activity for O2 hydrogenation, but the presence of SO2 significantly inhibits its activity. To operate the O2 hydrogenation catalyst without the risk of sulfur poisoning, the temperature should be above 200°C, preferably close to 250-350°C or higher.

[0059] Example III

[0060] exist Figure 3 In the process layout shown, after CO2 gas purification, the CO2 feed gas is mixed with H2 at a ratio of 3 mol H2 / mol CO2, making the mixed gas suitable for methanol production in the downstream synthesis unit.

[0061] The CO2 feed gas contains 1 vol% O2 and 5 ppm SO2. The CO2 feed gas is mixed with the entire H2 feed, compressed to 90 barg, and preheated to 185°C in a dedicated heat exchanger. Figure 3 The heat exchanger 7 is divided into a feed gas preheater with its own heat source (e.g., steam or electricity) and a feed / effluent heat exchanger connecting the cold side of the heat exchanger 7 to the hot end of the heat exchanger 18.

[0062] The feed gas, initially at 185°C, is then preheated to 300°C in the feed / effluent heat exchanger by heat exchange with hot gas from the outlet of the O2 hydrogenation reactor 11. At this temperature, the O2 hydrogenation catalyst is active and not poisoned by SO2 in the mixed gas. The O2 hydrogenation reaction is highly exothermic, raising the temperature by 35°C to 335°C, which is sufficient to compensate for the temperature difference in the feed / effluent heat exchanger. To control the reactor inlet temperature, 15-20% of the hot gas from the O2 hydrogenation reactor (17) bypasses the feed / effluent heat exchanger. The hot gas from the reactor is cooled to 195°C in the feed / effluent heat exchanger and mixed with the bypassed hot gas, ultimately reaching the downstream protective material (10) at a mixed temperature of 220°C, which is well within the optimal temperature range for the process. SO2 is hydrogenated to hydrogen sulfide and trapped at copper and zinc sites in the protective material. The purified process gas can then be directed to the methanol synthesis unit at a temperature suitable for the methanol converter.

[0063] Alternatively, a portion of the cold gas can be bypassed to the feed / effluent heat exchanger, instead of using the hot gas bypass method as described above.

[0064] Typically, feed / effluent heat exchangers are designed with a minimum temperature difference of 10-20°C to provide an economical and efficient heat exchanger. If the CO2 feed contains 0.2 vol% O2, the adiabatic temperature rise in the O2 hydrogenation reactor in this example will be 7°C, below the normal design rule. The design temperature difference can be reduced by increasing the heat exchange surface area, or a small auxiliary heater can be installed to raise the temperature to the required 3-13°C. In principle, a certain amount of O2 could also be added to the CO2 gas to provide more hydrogenation reaction and release more heat, but this option may be too expensive considering H2 consumption, and the additional water generated would reduce the capacity of the protective material and decrease the conversion efficiency of downstream methanol units.

[0065] An alternative solution is to perform O2 hydrogenation and sulfur removal before adding all the hydrogen; even using 3 vol% H2 would still be sufficient for O2 and sulfur hydrogenation. Due to the lower gas volume, the adiabatic temperature rise is now 21°C, allowing the feed / discharge heat exchangers to operate efficiently without modification.

[0066] When the O2 concentration is high in CO2-rich and H2-rich feed streams, the resulting water vapor can be advantageously removed upstream of the protective materials and synthesis apparatus. Methods for water removal include cooling the gas mixture below the water dew point, condensing the water, and removing a portion of it in liquid form.

[0067] The present invention has been described with reference to several aspects and accompanying drawings. However, those skilled in the art will be able to select and combine various aspects within the scope of the invention as defined by the appended claims. All documents referenced herein are incorporated herein by reference.

Claims

1. A method for purifying a CO2-rich gas feed (1), wherein the CO2-rich gas feed (1) contains at least 80 wt% CO2 and one or more sulfur-containing impurities; wherein the method comprises the following steps: - A CO2-rich gas feed (1) is passed together with a hydrogen-rich feed (2) through a protective material (10), and one or more sulfur-containing compounds are adsorbed onto the protective material (10) to provide a purified CO2-rich gas flow (50).

2. The method according to claim 1, wherein the CO2-rich gas feed (1) contains at least 90 wt% CO2, for example at least 95.0 wt% CO2, preferably at least 99 wt% CO2, more preferably at least 99.5 wt% CO2.

3. The method according to any one of the preceding claims, wherein one or more sulfur-containing impurities in the CO2-rich gas feed (1) are selected from organic sulfur compounds, such as thiols, sulfides, disulfides, sulfones, sulfoxides and thioketones, COS, SO3, SO2 and H2S, preferably H2S and SO2, and most preferably SO2.

4. The method according to any one of the preceding claims, wherein the protective material (10) has the activity of reducing SO2 to H2S and adsorbing H2S, and is preferably a Cu-Zn-Al protective material.

5. The method according to any one of the preceding claims, wherein a protective material (10) is located inside a reactor vessel (100), the reactor vessel (100) being arranged to receive the CO2-rich gas feed (1) and the hydrogen-rich feed (2) in the form of an optional mixture.

6. The method according to any one of the preceding claims, wherein the sulfur-containing impurity is SO2, and the SO2 concentration in the CO2-rich gas feed (1) is 0.1-50 ppm SO2, for example 1-10 ppm SO2, for example 1-5 ppm SO2.

7. The method according to any one of the preceding claims, wherein the CO2-rich gas feed (1) and / or the hydrogen-rich feed (2) further comprises oxygen (O2), and wherein the method comprises the following additional steps: - The CO2-rich gas feed (1) and the hydrogen-rich gas feed (2) are passed together through a catalyst (12) with oxygen hydrogenation activity to reduce the oxygen in the CO2 / H2 gas mixture, thereby providing a first oxygen-deficient CO2-rich gas stream. Then the following steps are performed: a first oxygen-deficient CO2-rich gas feed is passed through a protective material (10) to absorb one or more sulfur-containing impurities, thereby providing a purified CO2-rich gas flow.

8. The method according to any one of the preceding claims, wherein the total O2 content in the CO2-rich gas feed (1) is 50-10,000 ppm O2, for example 50-5,000 ppm O2, for example 100-3,000 ppm O2.

9. The method according to any one of the preceding claims, wherein more than 95% of the O2 is converted on a catalyst with oxygen hydrogenation activity, or the total concentration of O2 in the purified CO2-rich gas stream is < 200 ppm, for example < 100 ppm, for example < 50 ppm.

10. The method according to any one of the preceding claims, wherein the CO2-rich gas feed (1) and the hydrogen-rich feed (2) are passed through a catalyst (12) having hydrogenation activity at a temperature of 200-400°C and a pressure of 1-90 bar.

11. The method according to any one of the preceding claims, wherein after mixing the feed and passing the mixture through an optional O2 hydrogenation catalyst and protective material, the total H2 content in the combined feed of the CO2-rich gas feed (1) and the hydrogen-rich feed (2) is 0.2-10 vol% H2, for example 0.5-3 vol% H2.

12. The method according to any one of claims 1-9, wherein after mixing the feed, the total H2 content in the combined feed of the CO2-rich gas feed (1) and the hydrogen-rich feed (2) corresponds to a ratio of 2-5 moles of H2 / moles of CO2.

13. The method according to any one of the preceding claims, wherein after mixing the feed, the total H2O content in the combined feed of the CO2-rich gas feed (1) and the hydrogen-rich feed (2) does not exceed 10 vol%, preferably not more than 5.0 vol%, and more preferably not more than 1.0 vol%, for example about 0.5 vol%.

14. The method according to any one of the preceding claims, wherein the step of passing the CO2-rich gas feed (1) and the hydrogen-rich feed (2) through the protective material (10) is carried out at a temperature of 120-250°C and a pressure of 1-90 bar.

15. The method according to any one of the preceding claims, wherein more than 95% of one or more sulfur-containing impurities are retained on the protective material, or the total concentration of sulfur-containing impurities in the purified CO2-rich gas stream is < 500 ppb, for example < 100 ppb, for example < 50 ppb.

16. The method according to any one of the preceding claims, wherein the CO2 feed (1) originates from a renewable source, such as from: - Combustion or gasification of lignocellulosic biomass, such as wood products, algae, grass, forestry waste and / or agricultural residues; - Combustion or gasification of municipal waste, particularly its organic component, wherein municipal waste is defined as raw material containing materials of publicly discarded articles, such as mixed municipal waste as given in Annex IX, Part A of EU Directive 2018 / 2001 (RED II); - Microbial transformation of nitrogen-rich renewable feedstocks (such as feces or sewage sludge); - Fermentation of feed streams rich in hydrocarbons (sugars), such as corn, sugarcane, and sugar beets.

17. A method for producing a syngas stream, the method comprising the method according to any one of claims 1-16, and further comprising: - Provide at least a portion of the purified CO2-rich gas stream (50) obtained from the method of any one of claims 1-16; - Optionally, a second hydrogen-rich feed (202) is provided, which is optionally obtained from a water electrolysis process in one or more electrolysis units; - The purified CO2-rich feed (50) of this section is reacted with the second hydrogen-rich feed (202) to provide at least one stream of syngas (301).

18. The method according to claim 17, wherein the step of reacting the purified CO2-rich feed (50) of this portion with the second hydrogen-rich feed (202) to provide at least one synthesis gas stream (301) is carried out in the presence of a catalyst having reverse water-gas shift activity.

19. A method for producing a synthetic fuel stream, the method comprising the method according to any one of claims 17-18, and further comprising the step of converting the at least one synthetic gas stream (301) into at least one synthetic fuel stream, the synthetic fuel stream preferably being a MeOH stream, a synthetic fuel stream, or a TIGAS stream.

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