A process for the production of low carbon intensity carbon monoxide

Abstract

Implementations of the disclosed subject matter provide a process for gasification of biochar with CO2 to produce CO. The process may include a first feed stream having a CO2 concentration of at least 90 vol %, a second feed stream comprising biochar having a carbon concentration of at least 80 wt %, and a third feed stream having an oxygen concentration of at least 90 vol %. The ratio of CO2:C:O2 between the combination of the first, second, and third feed streams may be 0.7-1:1:0.1-0.2. The first, second, and third feed streams may be fed to a reactor for a combustion reaction and a reverse Boudouard reaction. A first product stream may be produced from the reactor comprising CO2, CO, and ash particles. The first product stream may be sent to a separator to produce a second product stream comprising ash particles and a gas product stream comprising at least 80% CO.

Description

A PROCESS FOR THE PRODUCTION OF LOW CARBON INTENSITY CARBON MONOXIDETECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a process of synthesizing low carbon intensity carbon monoxide (CO) from COg and biochar using a thermochemical process comprising of the reverse Boudouard reaction.BACKGROUND OF THE INVENTION

[0002] In general, the reverse Boudouard reaction has been studied extensively over the last 20 years because it consumes COg and produces CO. However, these studies have focused primarily on the kinetics, especially in lab scale facilities. Currently, the closest known processes for CO production from COg i.e., with low carbon intensity are the Reverse Water Gas Shift (RWGS) reaction (e.g., thermal, catalytic, or sorption enhanced) and COg electrolysis(e.g., solid oxide or low temperature) . However, the RWGS process produces a mixture of CO and Hg (i.e., syngas) . Hence, for applications requiring relatively pure CO streams (e.g., CO electrolyzer, Ube process, SHOP) an expensive cold box (e.g., a cryogenic unit) is necessary to separate the CO from the Hg . RWGS also requires Hg and COg as input that needs to be produced from renewable energy and this increases the cost and energy intensity of the process. COg electrolysis to CO requires as input renewable energy and COg to produce CO. Renewable energy can be intermittent if the source is from solar photovoltaic orwind . These further increase the costs and energy intensity of the COg electrolyzer .

[0003] Therefore , the production of CO from biochar and COg via a reverse Boudouard reaction is an attractive front end for a CO / CO2 to ethylene / ethanol electrolyzer as it reduces both the amount of CO2 that is required to make the CO and also the energy required for the overall process . The CO produced has net zero or net negative carbon intensity . SUMMARY OF THE INVENTION

[0004] According to an embodiment of the disclosed subj ect matter, a process for gasi fication of biochar with COg to produce CO may include a first feed stream having a COg concentration of at least 90 vol % , a second feed stream comprising biochar having a carbon concentration of at least 80 wt% , and a third feed stream having an oxygen concentration of at least 90 vol % . The molar ratio of COg : C : Og between the combination of the first , second, and third feed streams may be 0 . 7- 1 : 1 : 0 . 1- 0 . 2 . The first , second, and third feed streams may be fed to a single reactor for a combustion reaction and a reverse Boudouard reaction . A first product stream may be produced from the reactor comprising COg , CO, and ash particles . The first product stream may be sent to a separator to produce a second product stream comprising ash particles and a gas product stream comprising at least 80% CO .

[0005] Implementations of the disclosed subj ect matter provide a process for gasi fication of biochar with COg to produce CO . The disclosed subj ect matter allows for converting COg from various sources along with biochar togenerate CO that has a net zero or net negative carbon intensity. Additional features, advantages, and embodiments of the disclosed subject matter may be set forth or apparent from consideration of the following detailed description, figures, and claims. Moreover, it is to be understood that both the foregoing summary and the following detailed description are examples and are intended to provide further explanation without limiting the scope of the claims.BRIEF DESCRIPTION OF THE FIGURES

[0006] The accompanying figures, which are included to provide a further understanding of the disclosed subject matter, are incorporated in and constitute a part of this specification. The figures also illustrate embodiments of the disclosed subject matter and together with the detailed description serve to explain the principles of embodiments of the disclosed subject matter. No attempt is made to show structural details in more detail than may be necessary for a fundamental understanding of the disclosed subject matter and various ways in which it may be practiced .

[0007] FIG. 1 shows a process lineup according to an implementation of the disclosed subject matter.

[0008] FIG. 2 shows an example process lineup according to an implementation of the disclosed subject matter. DETAILED DESCRIPTION

[0009] In general, the reverse Boudouard reaction has been studied extensively over the last 20 years. However, these studies have focused on the kinetics, especially in lab scale facilities. Currently, the closest known processes for CO production from COg (i.e., with low carbonintensity) are the Reverse Water Gas Shift (RWGS) reaction (e.g., thermal, catalytic, or sorption enhanced) and COg electrolysis (e.g., solid oxide or low temperature) . However, the RWGS process typically produces a mixture of CO and Hg (i.e., syngas) . Hence, for applications requiring relatively pure CO streams (e.g., CO electrolyzer, Ube process, SHOP) an expensive cold box (e.g., a cryogenic unit) is necessary to separate the CO from the Hg . RWGS also requires Hg and COg as input that needs to be produced from renewable energy and this increases the cost and energy intensity of the process. COg electrolysis to CO requires as input renewable energy and COg to produce CO. renewable energy can be intermittent if the source is from solar photovoltaic or wind. These further increase the costs and energy intensity of the COg electrolyzer .

[0010] For alternative CO producing routes such as RWGS and COg electrolysis, the present invention provides a way of downsizing the overall energy requirements (e.g., renewable power or green Hg) and COg requirements (e.g., from DAC) . In general, electrochemically produced Og is also considered a waste product and is typically vented for state-of-the-art electrolyzer installations. The present invention achieves reduced energy requirements by receiving the necessary energy from combusting biochar with oxygen (preferably from a low carbon source like electrochemically produced Og ) and also reduces carbon dioxide requirement by utilizing biochar as a carbon source. As a result, the energy intensity (~0.44 kWh / kgCO) for this invention is roughly 90% lower than the reverse water gas shift process(~4kWh / kgC0) . Subsequently, one of the main advantages of the present invention is that the overall cost of the disclosed process is approximately 30% lower cost as compared to other alternatives, for example, reverse water gas shift process. Additionally, the present invention provides a viable way of producing relatively clean streams of CO (i.e., without the requirement of hydrogen as feed) . This is valuable for downstream process requiring CO as input (e.g., CO electrolysis, Ube process, SHOP) as the present invention eliminates the need for either an expensive requirement of a low carbon intensive hydrogen production process and also an expensive cryogenic section required to separate the CO and Hg from syngas-based routes .

[0011] As discussed above, the reverse Boudouard reaction has been studied extensively over the last 20 years. However, given the high endothermicity of the reaction, manageable ways of providing high temperature (>650 °C) heat to the reactor system have been lacking, thereby prohibiting scaleup. The present invention reduces the energy requirements (e.g., renewable power and / or green Hg ) and COg requirements (e.g., from DAC) by utilizing biochar as an additional source of carbon and energy, resulting in a hybrid DAC + bio + renewable power based route. Integration of the Og with the combustion of the biochar provides a manageable way of introducing large amounts of heat to the reverse Boudouard reactor at high temperatures .

[0012] Implementations of the disclosed subject matter provide a process for gasification of biochar with COg to produce CO. According to an embodiment of the disclosedsubject matter, a process for gasification of biochar with COg to produce CO may include a first feed stream having a COg concentration of at least 90 vol % , a second feed stream comprising biochar having a carbon concentration of at least 80 wt%, and a third feed stream having an oxygen concentration of at least 90 vol %. The molar ratio of COg : C : O2 between the combination of the first, second, and third feed streams may be 0.7-1 : 1 : 0.1-0.2. The first, second, and third feed streams may be fed to a single reactor for a combustion reaction and a reverse Boudouard reaction .

[0013] The reverse Boudouard reaction is (C + COg 2CO) , and it is considered a strong endothermic reaction that occurs at high temperatures.

[0014] A f irst product stream may be produced from the reactor comprising COg, CO, and ash particles. The first product stream may be sent to a separator to produce a second product stream comprising ash particles and a gas product stream comprising at least 80% CO.

[0015] According to various implementations of the disclosed subject matter, the feed streams in the process may be preheated to a desired temperature. In an implementation, the first feed stream may be preheated in a heat exchanger to a temperature in the range of 200-600°C. In another implementation, the second feed stream may be preheated in a heat exchanger to be at least 100°C. In yet another implementation, the third feed stream may be preheated in a heat exchanger to a temperature in the range of 100-200°C.

[0016] According to an embodiment, the process may further include mixing of the first, second, and third feedstreams in the reactor in step d) . Mixing may be accomplished by various methods known in the art, for example using a static mixer.

[0017] In an embodiment, the process may further include producing a third product stream from the reactor comprising ash, slag, and less than 5wt% carbon.

[0018] According to an embodiment, the process may also include cooling the first product stream in a heat exchanger prior to the separation step f) to a temperature in the range of 20-350°C.

[0019] According to various implementations of the disclosed subject matter, the process may be operated under various process conditions. In an implementation, the reactor in step d) may be operated at a temperature of at least 800°C. In another implementation, the reactor in step d) may be operated at a pressure in the range of 1-50 bara .

[0020] In an embodiment, the COg in the first feed stream may be from a source selected from the group consisting of: atmosphere, biogenic sources, biomass, and point sources from a chemical plant and / or refinery.

[0021] In an embodiment, the Og in the third feed stream may be from a source selected from the group consisting of: atmosphere, ocean, biogenic, electrochemical processes, chemical processes from chemical plant and / or refinery.

[0022] For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the accompanying figures, which are described in more detail below. The embodiments disclosed herein are not intended to be exhaustive or limit the invention to the precise form disclosed in thefollowing detailed description. The invention includes any alterations and further modifications in the illustrated devices and described methods and further applications of the principles of the invention as set forth in the claims.

[0023] FIG. 1 shows a process lineup according to an implementation of the disclosed subject matter. FIG. 1 shows an example of a process for gasification of biochar with COg to produce CO. As shown in FIG. 1, the process may include a first feed stream 110 having a COg concentration of at least 90 vol % , a second feed stream 120 comprising biochar having a carbon concentration of at least 80 wt%, and a third feed stream 130 having an oxygen concentration of at least 90 vol %. The molar ratio of COg : C : C>2 between the combination of the first, second, and third feed streams may be 0.7-1 : 1 : 0.1-0.2.

[0024] The first, second, and third feed streams 110, 120, 130 may be fed to a single reactor 20 for a combustion reaction and a reverse Boudouard reaction. A first product stream 210 may be produced from the reactor 20 comprising COg, CO, and ash particles. The first product stream 210 may be sent to a separator 30 to produce a second product stream 220 comprising ash particles and a gas product stream 230 comprising at least 80% CO.

[0025] Also shown in FIG. 1, the first feed stream 110 may be preheated in a heat exchanger 10 to a temperature in the range of 200-600°C. Similarly, FIG. 1 shows that the second feed stream 120 may be preheated in a heat exchanger 11 to be at least 100°C and the third feed stream 130 may be preheated in a heat exchanger 12 to a temperature in the range of 100-200°C.

[0026] Although not shown in FIG. 1, the first, second, and third feed streams 110, 120, 130 may be mixed inside reactor 20 in step d) .

[0027] As shown in FIG. 1, a third product stream 240 may be produced from the reactor 20 comprising ash, slag, and less than 5wt% carbon.

[0028] Also shown in FIG. 1, the first product stream 210 may be cooled in a heat exchanger 14 prior to the separation step f) to a temperature in the range of 20- 350°C.

[0029] Although not shown in FIG. 1, the process may be operated under various process conditions. For example, the reactor 20 in step d) may be operated at a temperature of at least 800°C. As another example, the reactor 20 in step d) may be operated at a pressure in the range of 1-50 bara .

[0030] Also not shown in FIG. 1, the COg in the first feed stream 110 may be from a source including atmosphere, biogenic sources, biomass, and point sources from a chemical plant and / or refinery.

[0031] Fo r the purposes of promoting an understanding of the principles of the invention, reference will now be made to the Examples carried out of various embodiments of the present invention, which are described in more detail below. The Examples and embodiments disclosed herein are not intended to be exhaustive or limit the invention to the precise form disclosed in the following Examples. The invention includes any alterations and further modifications in the provided Examples and described methods and further applications of the principles of the invention as set forth in the claims.

[0032] EXAMPLE:

[0033] The following Example is based on steady state process modeling that was simulated using ASPEN Plus Vll. The simulation basis was 1 million ton / year (or 3716 kmol / hr) CO production. FIG. 2 shows an example process lineup according to the disclosed subject matter.

[0034] According to the present invention, an example process for gasification of biochar with COg to produce CO was conducted. As shown in FIG. 2, a first feed stream 310 comprising COg may be from a DAC process (or other COg source) . The first feed stream 310 had a pressure of 1 bara and temperature of 20°C. The first feed stream 310 had a COg concentration greater than 90 vol% COg. As shown in FIG. 2, the first feed stream 310 was preheated in a heat exchanger 410 to 600°C and pressurized to 3 bara. A second feed stream 320 comprising biochar was preheated in a heat exchanger 420 to 350°C to remove all remaining moisture and pressurized to 3 bara. The second feed stream 320 was biochar with a carbon concentration greater than 80 wt% carbon. A third feed stream 330 comprising Og from an electrolyzer was preheated to 200°C in a heat exchanger 430 and pressurized to 3 bara. The third feed stream 330 had an Og concentration greater than 90 vol% Og . In order to preheat these three feed streams 310, 320, and 330, a total heat input of 35.3 MW was needed by the three heat exchangers 410, 420, and 430 (11.4 MW for heat exchanger 410, 23.5 MW for heat exchanger 420 and 0.4 MW for heat exchanger 430) .

[0035] As shown in FIG. 2, the three feed streams 310, 320, 330 were fed into the reactor 440 for a combustion reaction and a reverse Boudouard reaction. Inside thereactor 440, at least a portion of the biochar was combusted and the temperature in the reactor 440 increased. The reverse Boudouard reaction took place at 850°C and 3 bara. Inside the reactor 440, the combustion reaction was exothermic and the reverse Boudouard reaction was endothermic. Overall, the combination of the combustion reaction and the reverser Boudouard reaction in the reactor 440 was exothermic (i.e., -0.2 MW) .

[0036] As can be seen in FIG. 2, a first product stream 450 was produced from the reactor 440. The first product stream 450 comprising CO, ash, and remaining COg was sent to a heat exchanger 460 for heat recovery of -27.7 MW. The first product stream 450 was next sent to a gas / solid separator 470. In the separator 470, a second product stream 480 comprising ash was collected from the bottom and a gas product stream 490 comprising CO and remained COg was produced from the top. The gas product stream 490 had a temperature of 20°C and a pressure of 3 bara. The gas product stream 490 was sent to a compressor 500 where it was pressurized to 44 bara, requiring 10.7 MW power input, for downstream application.

[0037] Based on the Example, a total of 46 MW energy input (i.e., 0.44 kWh / kg CO) was needed for 1 million ton / year CO production (without heat recovery) . This is one of the advantages of the present invention, that the total energy input required is lower than previously known CO production according to alternative process such as Reverse Water Gas Shift process which requires, for example, 4 kWh / kg CO.Table 1: Summary of Process Streams according to theExample

[0038] As shown in Table 1 above, when the molar ratio between feedstocks C02 / carbon in biochar / 02is 0.7:1:0.15, the process achieves self-balance. When the ratio between feedstocks C02 / carbon in biochar / 02is outside of the claimed ratio, the overall efficiency of the process is not optimized and therefore results in excess CO2in the product stream that would require further treatment - thereby decreasing the productivity and efficiency of the process .

[0039] As shown in the provided Examples, the process for gasification of biochar with CO2to produce CO achieves reduced energy requirements by receiving the necessary energy from combusting biochar with oxygen (preferably froma low carbon source like electrochemically produced O2) and thereby also reduces the carbon dioxide requirement by utilizing biochar as a carbon source. As a result, the energy intensity (~0.44 kWh / kgCO) for this invention is roughly 90% lower than the alternative process in the prior art - reverse water gas shift process (~ 4 kWh / kgCO) . Subsequently, one of the main advantages of the present invention is that the overall cost of the disclosed process is a-proximately 30% lower cost as compared to other Alternatives, for example, reverse water gas shift process. Additionally, the present invention provides a viable way of producing relatively clean streams of CO (i.e., without the requirement of hydrogen as feed) . This is valuable for downstream processes requiring CO as input (e.g., CO electrolysis, Ube process, SHOP) as the present invention eliminates the need for either an expensive requirement of a low carbon intensive hydrogen production process and also eliminates an expensive cryogenic section required to separate the CO and Hg from syngas-based routes.

[0040] The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit embodiments of the disclosed subject matter to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to explain the principles of embodiments of the disclosed subject matter and their practical applications, to thereby enable others skilled in the art to utilize those embodiments as well as variousembodiments with various modifications as may be suited to the particular use contemplated.

Claims

C L A I M S1. A process for gasification of biochar with COg to produce CO, the process comprising: a) a first feed stream having a COg concentration of at least 90 vol % b) a second feed stream comprising biochar having a carbon concentration of at least 80 wt % c) a third feed stream having an oxygen concentration of at least 90 vol % , wherein the molar ratio of COg:C:Og between the combination of the first, second, and third feed streams is 0.7-1:1:0.1-0.2, d) feeding the first, second, and third feed streams to a single reactor for a combustion reaction and a reverse Boudouard reaction ( C + COg 2CO ) , e) producing a first product stream from the reactor comprising COg, CO, and ash particles, and f) subjecting the first product stream to a separation step in a separator to produce a second product stream comprising ash particles and a gas product stream comprising at least 80% CO.

2. The process for gasification of biochar with COg to produce CO according to claim 1, wherein the first feed stream is preheated in a heat exchanger to a temperature in the range of 200-600°C.

3. The process for gasification of biochar with COg to produce CO according to claim 1 or 2, wherein the second feed stream is preheated in a heat exchanger to be at least 100°C.

4. The process for gasification of biochar with COg to produce CO according to any of claims 1 to 3, wherein the third feed stream is preheated in a heat exchanger to a temperature in the range of 100-200°C.

5. The process for gasification of biochar with COg to produce CO according to any of claims 1 to 4, further comprising mixing of the first, second, and third feed streams in the reactor in step d) .

6. The process for gasification of biochar with COg to produce CO according to any of claims 1 to 5, further comprising producing a third product stream from the reactor comprising ash, slag, and less than 5wt% carbon.

7. The process for gasification of biochar with COg to produce CO according to any of claims 1 to 6, further comprising cooling the first product stream in a heat exchanger prior to the separation step f) to a temperature in the range of 20-350°C.

8. The process for gasification of biochar with COg to produce CO according to any of claims 1 to 7, wherein the reactor in step d) is operated at a temperature of at least 800°C.

9. The process for gasification of biochar with COg to produce CO according to any of claims 1 to 8, wherein the reactor in step d) is operated at a pressure in the range of 1-50 bara.

10. The process for gasification of biochar with COg to produce CO according to any of claims 1 to 9, wherein the COg in the first feed stream is from a source selected from the group consisting of: atmosphere, biogenic sources,5 biomass , and point sources from a chemical plant and / or refinery .

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