REGENERATIVE SYNTHESIS OF CHEMICAL ENERGY STORAGE AND FINE CHEMICALS

Description

[0001] The invention relates to devices and methods for producing chemical energy storage devices in the form of energy-rich organic compounds as well as fine chemicals from renewable and biogenic sources, in particular from carbon dioxide-containing substrates, in particular for use in decentralized plants, for example plants powered by electricity from renewable sources.

[0002] The conversion and storage of energy from renewable sources, especially carbon dioxide (CO2), in energy-rich organic molecules (CO2 fixation) represents a major challenge. Organic waste streams, and in particular the exhaust gas CO2, are to be utilized as materials and used to synthesize chemicals, particularly new chemical energy storage systems or products with an overall positive energy balance. The conversion into short- or long-chain hydrocarbons as energy carriers has so far been the primary focus. Alternatively or additionally, the substrates from renewable sources could also be directly converted into usable fine chemicals. Fine chemicals can be used for the further synthesis of complex compounds, such as biopolymers.

[0003] However, renewable and especially biogenic sources are often found in a decentralized manner due to their nature, for example in the form of exhaust gas purifiers in individual industrial plants and power plants or as biogas plants. It is therefore desirable to be able to convert and store the energy from them in a decentralized manner and in small-scale local plants. In contrast, known processes, such as Fischer-Tropsch synthesis for the production of new organic compounds from synthesis gases, are complex and, above all, not suitable for decentralized plants, especially for the utilization of relatively small amounts of gas from biogas plants or from exhaust gas purification. In addition, known plants and processes have a poor overall energy balance, as they are primarily focused on the final product yield and quality.

[0004] Use procedural guidance.

[0005] DE 10 2011 112093 discloses a low-pressure methanol reactor for producing methanol from synthesis gas via copper-catalyzed heterogeneous catalysis at temperatures of 200-300 °C. The reactor also includes a methanol storage tank and water separators, scrubbers, and condensation devices.

[0006] FRANK SONNTAG ET AL: "Engineering Methylobacterium extorquens for de novo synthesis of the sesquiterpenoid [alpha]-humulene from methanol", METABOLIC ENGINEERING, Vol. 32, November 1, 2015, discloses an apparatus and a method for the aerobic fermentation of methanol on methanol-fixing Methylobacter microorganisms to produce terpenes as a chemical energy storage medium.

[0007] The present invention is based on the technical problem of providing new processes and devices for the synthesis of fine chemicals and chemical energy storage from renewable, in particular CO2-containing substrates, which can also be operated in integral plants and small modules and with high efficiency and have a favorable overall energy balance because the energy input into the system is low.

[0008] The invention provides methods and means in the form of a readily scalable complete system for the direct, integral, i.e., combined chemocatalytic and biotechnological synthesis of chemical energy storage from CO2-containing synthesis gas mixtures. The invention utilizes the finding that, by chemocatalytic means, primarily methanol-containing substrates can be synthesized from CO2- and H2-containing gas mixtures, such as those regeneratively obtained in biogas plants or exhaust gas purification systems and through electrolysis, initially at atmospheric or low pressure. These substrates then serve directly, especially without further purification or intermediate storage steps, as a substrate for primarily methanol-fixing microorganisms in an aerobic fermentation.This biotechnological process, which can be directly followed by the chemical synthesis of the methanol-containing substrate, can produce products and product mixtures that, in the form of energy-rich organic molecules, can be used as chemical energy storage media and / or directly as fine chemicals. The integrated design of the entire system also advantageously allows for the efficient recycling of generated reaction heat within the system itself, particularly for preheating the synthesis gas and / or for controlling the temperature of the cell culture medium in the biotechnological process. Therefore, the supply of external energy, such as electrical energy, for the continuous heating and / or cooling of individual system components can be dispensed with.

[0009] The first aspect of the invention is therefore a device, that is to say a complete plant, for the integral synthesis of organic energy storage molecules or fine chemicals from a CO2- and H2-containing synthesis gas mixture, wherein the device according to the invention has at least the following elements connected directly one after the other in the direction of material flow: (1) low-pressure gas reactor, that is to say in particular a methanol synthesis reactor which contains a heterogeneous catalyst, in particular a copper-based one, for the purpose of the catalytic synthesis of a methanol-containing product mixture from the CO2- and H2-containing synthesis gas;(2) Condenser or cold trap, located directly downstream of the low-pressure gas reactor, for liquefying the methanol-containing gas obtained in the low-pressure gas reactor into a liquid methanol-containing substrate, wherein, in particular, the non-liquefiable, i.e., non-condensable, residual gases are separable from the methanol-containing gas and, in particular, recirculated to the low-pressure gas reactor; (3) Fermentation reactor, located directly downstream of the condenser, containing liquid cell culture medium and special methanol-fixing microorganisms for the purpose of aerobic fermentation of the methanol-containing substrates to produce organic energy storage materials or fine chemicals.

[0010] This device preferably also contains a gas dosing unit, particularly immediately upstream of the low-pressure gas reactor or methanol synthesis reactor, for the purpose of dosing the CO2- and H2-containing synthesis gases into the low-pressure gas reactor. The gas dosing unit controls the material flows into the synthesis reaction and thus preferably the overall process. Preferably, this gas dosing unit additionally contains a gas storage unit, particularly immediately upstream of it, for the purpose of temporarily storing the CO2- and H2-containing synthesis gases. For the purpose of returning non-liquefiable residual gases, particularly CO2, CO2-containing gases, and DME, from the condenser, a return line is preferably provided between the condenser and this gas storage unit.In this way, it can be advantageously ensured that the residual gases are passed through the low-pressure gas reactor again in order to increase the conversion of the catalytic synthesis to methanol-containing gases and ultimately to the methanol-containing substrate.

[0011] The inventive, integral, direct interconnection of these components allows the reaction heat generated during the catalytic synthesis of the methanol-containing gas in the low-pressure gas reactor to be utilized directly in the device itself. This is achieved, on the one hand, by a gas heater upstream of or integrated into the low-pressure gas reactor, which, according to the invention, is preferably fed via a heat exchanger connected to the low-pressure gas reactor, which removes reaction heat from the low-pressure gas reactor, in order to bring the synthesis gas to a favorable reaction temperature before it enters the reactor. On the other hand, it is preferably or alternatively provided that the fermentation reactor, which contains the cell culture medium, is temperature-controlled via a media heater associated with or integrated with the fermentation reactor in order to maintain a constant optimum cultivation conditions for the methanol-fixing microorganisms contained therein.The media heater is fed by the waste heat from the condenser, in particular via a cooling jacket and heat exchanger arranged on the condenser.

[0012] The invention also relates to a specially designed, novel condenser for the efficient condensation, i.e., liquefaction, of methanol-containing gases, which can form a preferred component of the device according to the invention. This consists of a particularly cylindrical, elongated chamber that is primarily oriented vertically during operation. Formed within the chamber is an upper gas section, which is gas-filled during operation, and a lower liquid section, which is liquid-filled during operation. On the chamber, in the region of the upper gas section, there is at least one upper connection for discharging non-liquefiable residual gases. A lower connection is formed in the lower liquid section for discharging the methanol-containing substrate formed in the condenser.Gaseous methanol-containing mixtures, such as those originating in particular from the low-pressure gas reactor immediately upstream, can be fed into the chamber via a further connection. This connection opens into a gas pipe inside the chamber, which according to the invention is immersed in the liquid section of the chamber and thus, during operation, into the liquid present there. Preferably, the gas pipe is made of a heat-conducting material, plastic or metal, and is additionally bent in a helical or spiral manner in order to increase the contact of the gas pipe with the liquid present there. The chamber is surrounded by a cooling jacket. The liquid, in particular water, present in the chamber during operation is cooled, and the heat introduced into the liquid by introducing hot gas is dissipated.Without wishing to be bound by theory, the methanol-containing gas cools as it passes through the immersed gas tube due to the cooler liquid surrounding it, and partially exits the lower, open end of the gas tube already in liquid form. In this way, the methanol-containing gas is advantageously condensed in the liquid present there, particularly water, like a cold trap. This results in an aqueous solution of the methanol-containing substrate. Non-condensable residual gas rises from this liquid and can be removed from the chamber through the additional upper connection for discharging the non-liquefiable residual gases or expelled by inert purge gas (N2).

[0013] The fermentation reactor of the device is constructed in a conventional manner. The methanol-fixing microorganisms are preferably selected from bacteria of the genera Methylobacterium, Cupriavidus, Methylocella, or yeasts of the genus Pichia. In addition, other microorganisms can be used that are capable of utilizing methanol, in particular as the sole carbon source, and of synthesizing organic molecules from it, which can serve as chemical energy stores and / or fine chemicals. However, the microorganisms are preferably selected from Methylobacterium sp., for example, Methylobacterium extorquens (AM1). Microorganisms that do not originally utilize methanol but are still being cultivated for this purpose can also be used.

[0014] In a preferred embodiment, a harvesting and material separation unit is arranged downstream of the fermentation reactor, or alternatively, is integrated into it. This unit is specifically designed to separate the organic energy storage molecules or fine chemicals, particularly terpenes or terpene-containing product mixtures, synthesized therein by biotechnology from the cell culture medium or the cells, whereby the products can then be isolated. In the case of products that are insoluble or not directly released into the cell culture medium, the material separation unit provides for the separation of the cells from the cell culture medium (harvesting) and the disruption of the cells to release the biotechnologically formed products in a conventional manner. Other products include bioplastics, bioadditives and precursors thereof (PHB), as well as food and feed or additives such as proteins, oils, and fats.

[0015] In a practical embodiment, the device is specifically designed and its control system is programmed accordingly so that the low-pressure reactor is primarily operated continuously, the liquefaction of the methanol-containing substrate is carried out batchwise, with optional recirculation of the residual gases to the catalytic process, and the fermentation runs in fed-batch mode, with methanol-containing substrate periodically metered from the condenser into the fermentation reactor. After fermentation is complete, the final product or product mixture is separated from the microorganisms and / or the culture medium, and the fermentation reactor is refilled and inoculated. For this purpose, the device features additional, known valves and fluid connections in a specific configuration.In a particular variant, a valve arrangement and / or additional connections are provided on the condenser to introduce liquid, in particular water, into the liquid section of the chamber in a preparatory step. The condensation of the methanol-containing substrate takes place in this liquid. The initial liquid, ultimately enriched with methanol-containing substrate, is periodically drained. The interior of the chamber can be purged with inert gas via the valve arrangement and / or additional connections, and the residual gases can be expelled. In one variant, a valve arrangement and / or dosing device is provided between the condenser and the fermentation reactor, allowing controlled dosing of the methanol-containing substrate into the fermentation.

[0016] A "CO2-containing synthesis gas" is understood here as a mixture with the main components hydrogen (H2) and carbon dioxide (CO2). These are preferably present in a molar ratio of 3 parts H2 to 1 part CO2. Other components of this synthesis gas can include carbon monoxide (CO), but also methane (CH4) and other volatile organic substances, such as those found in biogas plants. The presence of oxygen (O2) should preferably be avoided. Advantageously, such CO2-containing synthesis gas can be obtained directly from the gas mixture of a biogas plant. CO2 can alternatively or additionally be obtained as a product of alcoholic fermentation. Alternatively or additionally, portions of methane (CH4) in a biogas can be converted to H2-containing synthesis gases, particularly by dry reforming with CO2 or steam reforming.Alternative sources include converter gas from iron production (CO, CO2), especially in combination with coke oven gas from iron production (H2, CH4), as well as excess CO2 from sugar production, CO2 off-gas from cement production, spring carbon dioxide, and CO2 and CO from combustion gases (off-gas and flue gas scrubbers). A CO2-containing gas fraction can thus be enriched with an H2 fraction obtained from other sources, particularly from renewably generated sources, to obtain the appropriate synthesis gas mixture. A preferred source of H2 is electrolysis, particularly in photovoltaic systems, coke oven gas, or dry or steam reforming.

[0017] In a preferred embodiment, the CO2-containing synthesis gas is a mixture of at least CO2, H2, and CO, which, in a special variant, additionally contains other gases that are essentially inert during a methanol synthesis reaction. These include, in particular, N2, Ar, and CH4.

[0018] In a preferred embodiment, a stoichiometric ratio (SR) is maintained, which is defined by: SR = (C[H2]-C[CO2]) / (C[CO]+C[CO2]).

[0019] The term "C[ ]" in brackets refers to the molar concentration of the component mentioned. The stoichiometric ratio (SR) is from 1 to 3, preferably from 1.5 to 2.5, particularly preferably from 1.8 to 2.3, further preferably between 1.8 and 2.3, more than 1.8, and less than 2.3.

[0020] In a preferred embodiment, the CO2-containing substrate is essentially free of O2, H2S, NH3, COS, amines, volatile metal compounds, halogen compounds, sulfur compounds, or compounds of elements of the sixth main group (chalcogens). Furthermore, the CO2-containing substrate is preferably essentially or completely free of tar or tar components. A synthesis gas containing essentially only CO2 and H2 can be obtained in a preferred embodiment by, on the one hand, obtaining H2, in particular by water electrolysis, and by obtaining CO2 from one or more CO2 sources from the group consisting of: highly concentrated CO2 gas stream from the fermentation of sugar-containing substrates to ethanol-containing products or liquids, from the fermentation of sugar-containing substrates to lactic acid-containing substrates, from the fermentation of sugar-containing substrates of 2,3-butanediol, from the fermentation of methanol-containing substrates to organic compounds; from milk processing; from the recovery of CO2 from the atmosphere; from the degassing of mineral water from mineral water springs or hot springs; from biogas; from limestone processing and cement production; from the combustion of naturally occurring gases, synthetic gases, biomass, biogas, wood, refined or unrefined petroleum fractions, cracked products, petroleum fractions; and from waste incineration.

[0021] In an alternative embodiment, CO2-, CO- and H2-containing synthesis gas is obtained from one or more of the following group of synthesis gas sources, consisting of: synthesis gas from steam reforming, autothermal reforming or dry reforming of biogas; from biomass gasification, biomass pyrolysis; from the gasification of products of incomplete carbonization (semi-coke) as obtained in pyrolysis, from gasification in the presence of H2; from steam reforming, autothermal reforming, dry reforming, adsorption-enhanced reforming of biomass, of pyrolysis oil or of tar from biomass; from steam reforming, autothermal reforming or dry reforming of alcohols, biogenic oils and fats; from steam reforming, autothermal reforming or dry reforming of natural gas; from the partial oxidation of natural gas;from steam reforming, autothermal reforming, dry reforming, or adsorption-enhanced reforming or partial oxidation of mineral oil distillates or mineral oil cracking products; from coke oven gases; from blast furnace flue gases; from coal gasification, coal pyrolysis, semi-coke gasification, obtainable from coal pyrolysis; and from steam reforming, autothermal reforming, dry reforming, or adsorption-enhanced reforming of coal tar distillates. Interfering substances such as O2, H2S, NH3, COS, tar or tar products, and volatile metal compounds, halogen compounds, sulfur compounds, or compounds of elements of the sixth main group (chalcogens) are preferably substantially or completely removed from the synthesis gas.

[0022] In connection with the adjustment of the preferred stoichiometric ratio (SR), the initially obtained synthesis gas can be adjusted by water gas shift reaction, by reverse water gas shift reaction, by addition of H2 from other sources (e.g. water electrolysis), from ammonia degradation or from degradation of liquid organic hydrogen carriers.

[0023] A "methanol-containing gas" is understood here to mean the gaseous product mixture obtained from the aforementioned CO2-containing synthesis gas by heterogeneous catalysis, which contains methanol (CH3OH) as its main component. Other components in this gas mixture may include unreacted synthesis gas and byproducts, particularly CO2, CO, and H2, as well as dimethyl ether (DME). Besides DME, byproducts may also include ethanol and other substances.

[0024] A "methanol-containing substrate" is understood herein to mean the liquid mixture obtained by condensation, i.e., cooling, from the methanol-containing gas. Compared to the methanol-containing gas, the non-condensable fraction, i.e., the non-liquefiable gas components, especially CO2, CO, and H2, remain in the gas phase and are separated, and are therefore missing. However, other condensable byproducts of methanol synthesis may be present in the methanol-containing substrate. In an alternative embodiment, the methanol-containing substrate is pure methanol. The substrate is preferably dissolved in aqueous solution in the condenser of the device according to the invention and can thus be withdrawn at the condenser and directly introduced into the subsequent process stage, biological fermentation.The inventors were surprised to find that this methanol-containing substrate can be used directly as a substrate for methanol-fixing microorganisms to produce biotechnologically organic energy storage products and / or fine chemicals. Known methanol-fixing microorganisms can also be used.

[0025] "Chemical energy storage" primarily refers to organic molecules with a high energy content that can later be used for energy recovery, particularly in oxidative processes such as combustion or respiration. These include, in particular, higher-value alkanes, alcohols, or organic acids, but also, in particular, fine chemicals such as terpenes, especially carotenes, α-pinene, and isoprene, or polyhydroxyalkanoates, for example, for the production of biopolymers. (1) In a first step, the CO2-containing synthesis gas is provided. (2) In a second step, a methanol-containing gas is synthesized from the synthesis gas, particularly on copper-based heterogeneous catalysts. Isothermal temperature control is preferred, with the heat of reaction being controlled by specific dimensioning of the reaction zone and catalyst. The reaction temperature of the catalysis is preferably more than about 250°C, in particular from 250°C to 300°C, but preferably always more than 250°C and up to a maximum of 300°C. In a particular embodiment, the reaction temperature is between 200°C and 300°C, preferably between 220°C and 290°C, particularly preferably between 240 and 290°C.

[0026] According to the invention, this reaction is carried out under pressure, i.e. at approximately atmospheric pressure, or alternatively at low pressure or slight overpressure down to less than 10 bar overpressure, preferably down to less than 5 bar overpressure, particularly preferably down to less than 3 bar overpressure. In a particular variant, the reaction pressure is always less than 150 bar overpressure, preferably less than 100 bar, particularly preferably less than 50 bar. Especially for decentralized systems, the reaction pressure is approximately atmospheric pressure. This particularly preferably results in an improvement in the overall energy balance, specifically in small-format decentralized systems which can be operated particularly at atmospheric pressure or slight overpressure, i.e. particularly less than 20 bar overpressure, preferably less than 15 bar overpressure and particularly preferably less than 10 bar overpressure.

[0027] It has surprisingly been shown that even under these low-pressure conditions, a sufficiently high specificity and selectivity of heterogeneous catalysis prevails, so that a methanol-containing product mixture can be obtained, which can be directly fed to aerobic fermentation by known methanol-fixing microorganisms, provided that only non-condensable residual gases such as CO and H2, or CO2, CO2-containing gases, and H2, are separated beforehand. This process makes it possible to provide an integral system for combined chemocatalytic and biocatalytic synthesis that is essentially pressureless or can always be operated with only a low pressure pulse (low pressure), in which all components can be connected directly in series and integrated.By conducting the process at atmospheric or low pressure, energy-intensive pumps and pressurization systems in the plant can be completely eliminated, which can significantly positively impact the overall energy balance. The elevated reaction temperature of 250 °C or more, particularly in the range between 200 °C and 300 °C, preferably between 220 °C and 290 °C, and particularly preferably between 240 °C and 290 °C, can be maintained directly from the reaction heat of the synthesis. (3) In a subsequent further step, the methanol-containing gas thus obtained is condensed by cooling, with non-condensable residual gases being separated and removed. The condensation of the gas is preferably carried out by introducing it into a cooled aqueous solution, particularly water, which ultimately yields an aqueous solution of a methanol-containing substrate. (4) In a subsequent further step, the thus condensed liquid methanol-containing substrate is fed or metered directly into a fermentation reactor, and methanol-fixing microorganisms are cultivated in this fermentation reactor in cell culture medium under aerobic fermentation conditions, with the supplied methanol-containing substrates being converted into organic energy storage molecules or fine chemicals. The resulting product mixture is then separated and isolated from the cells and / or the cell culture medium.

[0028] The invention also relates to a mixture of organic energy storage molecules or a terpene-containing product mixture which can be produced from the CO2-containing synthesis gas by means of this process, preferably using the device according to the invention.

[0029] The invention is described in more detail by the figures and the following description of specific embodiments. Figure 1Ashows the basic structure of the device according to the invention in a schematic representation: a low-pressure gas reactor 30 or methanol synthesis reactor for heterogeneous catalysis is preceded by a gas heating unit 38, which is preferably fed with the reaction heat of the heterogeneous catalysis via a heat exchanger 36 on the low-pressure gas reactor 30 in order to preheat the synthesis gas before it enters the catalysis. A gas metering unit 20, which is fed from a gas storage unit 10, is preceded by the low-pressure gas reactor 30. A condenser 40, which serves as a cold trap, is connected downstream of the low-pressure gas reactor 30 to cool the methanol-containing gas product emerging from the low-pressure gas reactor 30 and to condense, i.e., liquefy, condensable components, primarily methanol, from it.The liquefied methanol-containing substrate is fed to the immediately downstream fermentation reactor 50 via a metering valve, whereas non-condensable residual gases are pumped back to the gas storage 10 via a separate return line 60. This is preferably done by an active low-pressure pump 62 in the return line 60. The condenser 40 is actively cooled by a cooling jacket (cooling coil) with a heat exchanger 46. The heat extracted there is fed to a media heating unit 58 arranged on the fermentation reactor 50, which serves to regulate the temperature of the cell culture medium. Methanol-fixing microorganisms 54 are present in the cell culture medium of the fermentation reactor 50.During aerobic fermentation, these methanol-fixing microorganisms convert the methanol-containing substrate directly fed via the condenser into organic energy stores or into fine chemicals such as terpene-containing product mixtures, which can be isolated from the fermentation in a harvesting and separation unit 70. Figure 1B shows a special version of the device according to Figure 1A , wherein a further heat exchanger circuit 80 can be connected in shunt connection in the heat exchange circuit 46 for heat exchange at the condenser 40. The heat exchanger 80 serves, particularly during continuous operation of the condenser 40, to remove additional heat from the system, i.e., primarily the reaction heat that is not required for tempering the medium 54 in the fermentation reactor 50. Figure 1C shows another special embodiment of the device according to Figure 1Aor 1B, wherein in addition to the heat exchanger 36 for returning reaction heat to the system via heat exchanger 38 on the reactor 30, an additional heat exchanger 96 is provided, which is connected to a steam generator 94, wherein the reaction heat removed from the reactor 30 can be used to generate steam. The steam is withdrawn from the steam generator and can be used to preheat the synthesis gas (syngas). The steam generated by systems 96, 94 can also be used to generate low- to medium-pressure steam, which can be used to generate the synthesis gas. Alternatively or additionally, a high-pressure steam reactor 98 is provided on the reactor 30, which is fed by the reaction heat from the reactor 30. High-pressure steam can then be withdrawn via line 92 and used to generate the synthesis gas. Figure 2shows a schematic representation of an embodiment of the low-pressure gas reactor 30 according to the invention: A reaction tube 33 made of quartz glass, in which the particulate catalyst 34 is located, is inserted into a heat-conducting reactor block 31 made of aluminum. The synthesis gas preheated in the gas heater 38 enters the reaction tube 33 (top in the image). The synthesized methanol-containing gas can be withdrawn at the reactor outlet (bottom in the image). A heating cartridge 35 is also provided in the reactor block 31 shown, which can initially bring the reactor to reaction temperature in order to start the reaction. The reactor block is surrounded by an insulating jacket, which serves as a heat exchanger 36 to dissipate reaction heat from the reactor. Figure 3shows a schematic representation of an embodiment of the condenser 40 according to the invention. A helically bent gas pipe 47, open at the end, is suspended in a substantially cylindrical chamber 38, through which methanol-containing gas can be supplied. For this purpose, the gas pipe 47 is connected to a connection 45. In the upper gas section 43, which is gas-filled during operation of the condenser 40, an upper connection 44 is provided, which is specifically designed to discharge non-liquefiable residual gases, namely via the return line 60. In the lower liquid section 42, which is liquid-filled during operation, the gas pipe 47 is immersed in the liquid. There, the methanol-containing gas condenses to form a methanol-containing substrate, which can be withdrawn via the lower connection 41 to discharge the liquefied substrate. The jacket of the chamber 48 is actively cooled by a heat exchanger 46 designed as a cooling coil.The liquid can be introduced via line 49, but samples can also be taken from the ongoing process. Example: Combined chemical and biotechnological synthesis of terpenes from a gas mixture of CO2 and H2

[0030] CO2 and H2 gases from various sources are placed in a gas storage tank at a molar ratio of 1:3. The gas is metered into a heated tubular reactor via a mass flow controller (Bronkhorst MFC). The CO2 gas flow rate ranges from 2.5 to 50 ml / min, while the H2 gas flow rate ranges from 10 to 200 ml / min. The pressure of the gases from the storage tank upstream of the mass flow controller is approximately 3 bar; after passing through the mass flow controller, the gases enter the tubular reactor at approximately atmospheric pressure. An overpressure of 20-30 mbar is sufficient to maintain the gas flow through the reactor. The synthesis reaction, which is inherently volume-increasing, leads to negligible effects when operated at atmospheric pressure.

[0031] The low-pressure reactor consists of a cylindrical aluminum block preheated with an electric heating cartridge, within which a 10 mm diameter quartz tube filled with particulate catalyst material is embedded. The reaction zone in the quartz tube is approximately 15 cm long. The reactor components are dimensioned to enable isothermal reaction. On a laboratory scale, the material throughput is increased by connecting several reactor tubes in parallel within a block.

[0032] The temperature inside the tubular reactor is approximately 250 °C during the reaction; the heterogeneous catalytic synthesis reaction proceeds isothermally. The reaction heat generated in the reactor is dissipated and heats the synthesis gas to approximately 120 °C before it enters the reactor. In an alternative approach, a high-temperature steam heater or an oil heater is installed instead of the electrical preheating of the tubular reactor. In an alternative approach, the catalyst material is heated directly using microwave radiation.

[0033] The heterogeneous catalyst in the tubular reactor is a particulate copper mixed metal catalyst based on zinc oxide (ZnO) and alumina (Al2O3) with a content of approximately 30 to 70 wt.% Cu, approximately 20 to 50 wt.% Zn, and approximately 10 to 20 wt.% Al, with the copper contact preferably in nanoparticulate form with a metal particle size of 1 to 100 nm. The catalyst is precipitated in a conventional manner from the salts copper nitrate (trihydrate), zinc nitrate (hexahydrate), and aluminum nitrate (nonahydrate). The average size of the catalyst grains is 200 to 320 µm.

[0034] The reaction product emerging from the tubular reactor, a methanol-containing gas mixture with residual gases, is liquefied in a cold trap located immediately downstream. The cold trap consists of a cylindrical flask with jacket cooling. A helically bent gas tube is immersed in approximately 15 ml of water. The methanol gas is liquefied by cooling, and methanol and any by-products dissolve in it. The methanol concentration in the resulting aqueous solution is approximately 1.5 to 15 mmol / L. Insoluble and non-condensable residual gas components are removed from the top of the reactor flask and pumped back into the gas reservoir via a return line. The aqueous solution of the methanol-containing substrate is removed from the bottom of the flask and metered into the directly connected fermentation reactor.

[0035] This cold trap is operated in a batch process: In a first phase, liquid is placed in the flask, in a second phase the methanol-containing gas mixture is introduced into the cooled liquid and condensed there. In a third phase, externally supplied inert purge gas (N2) is pumped through the tube immersed in the liquid instead of the methanol-containing gas mixture from the reactor, in order to expel non-condensing residual gas, consisting in particular of catalysis by-products such as carbon monoxide (CO) and dimethyl ether (DME), as well as unreacted synthesis gas components (CO2, H2) from the cold trap and return it to the receiver, in particular via the return line.

[0036] The fermentation reactor contains a cell culture medium inoculated with microorganisms of the genus Methylobacterium extorquens (AM1). The bacteria are specifically selected to produce terpenes, particularly carotenes, from the methanol-containing substrate as a carbon source. These are accumulated in the microorganisms. Cultivation takes place in fed-batch mode at a temperature of approximately 20 to 28 °C with constant mixing and aeration with purified compressed air. The cultivation period is 1 to 3 days.

[0037] Following cultivation, the accumulated carotenes are extracted from the microorganisms. For this purpose, the cells are harvested from the culture medium and mixed with DMSO in a conventional manner, disrupted, and centrifuged. The pellet yields carotenes, which can then be dried.

[0038] The amount of carotene is determined spectrophotometrically (510 nm) by correlation with a reference substance (dried carotene). Approximately 10 to 30 mg of carotene per gram of biomass are obtained. The total yield of the fermentation is 6 mg of carotene per 1 g of methanol substrate.

Claims

1. A device for the integral synthesis of organic stored-energy sources from carbon dioxide-containing synthesis gas, containing elements connected directly in series in the direction of material flow: - a low-pressure gas reactor (30) with a copper-based heterogeneous catalyst (34) for the catalytic synthesis of a methanol-containing gas from the synthesis gas, - a condenser (40) connected directly downstream of the low-pressure gas reactor (30) for liquefying this methanol-containing gas into a liquid aqueous methanol-containing substrate and for discharging non-liquefiable residual gases, - a fermentation reactor (50) connected directly downstream of the condenser (40), containing liquid cell culture medium and methanol-fixing microorganisms (54) for the aerobic fermentation of methanol-containing substrates to organic stored-energy sources, for receiving this condensed liquid aqueous methanol-containing substrate.

2. The device of claim 1, further containing a gas dosing unit (20) connected directly upstream of the low-pressure gas reactor (30).

3. The device of claim 2, further containing a gas storage unit (10) connected directly upstream of the gas dosing unit (20).

4. The device of claim 3, further containing a return line (60) between the condenser (40) and the gas storage unit (10) for returning the non-liquefiable residual gases from the condenser (40) to the gas storage unit (10).

5. The device of one of the preceding claims, further containing a substance separating unit (70) connected downstream of the fermentation reactor (50) for separating the synthesised organic stored-energy sources from the microorganisms and / or the cell culture medium.

6. The device of one of the preceding claims, further containing a gas heating unit (38) connected directly upstream of or integrated into the low-pressure gas reactor (30) for preheating the synthesis gas before or upon entry into the catalysis, wherein the gas heating unit (38) is supplied with the reaction heat generated in the low-pressure gas reactor (30) via a heat exchanger (36) assigned thereto.

7. The device of one of the preceding claims, further containing a media heating unit (58) assigned to or integrated into the fermentation reactor (50) for controlling the temperature of the cell culture medium in the fermentation reactor (50), wherein the media heating unit (58) is supplied with the heat to be removed from the condenser (40) via a heat exchanger (46) assigned thereto.

8. The device of one of the preceding claims, wherein the condenser (40) further contains: - a chamber (48) having an upper gas section (43) having an upper port (44) for discharging non-liquefiable residual gases and a lower liquid section (42) having a lower port (41) for discharging the liquefied methanol-containing substrate, - a gas pipe (47) connected to a port (45) and immersed in the lower liquid section (42) for introducing the gaseous methanol-containing substrate into the liquid section (42) of the chamber (48).

9. A method for the integral synthesis of organic stored-energy molecules from carbon dioxide-containing synthesis gas, containing the steps: - providing synthesis gas containing CO2 and H2; - synthesis of methanol-containing gas from the synthesis gas on a copper-based heterogeneous catalyst at a temperature of 250 to 300 °C and at atmospheric pressure or low pressure of less than 5 bar overpressure; - condensing the directly obtained methanol-containing gas to a liquid aqueous methanol-containing substrate and discharging non-condensable residual gases; - directly feeding the liquid aqueous methanol-containing substrate into a fermentation reactor; - Cultivating methanol-fixing microorganisms in the fermentation reactor in cell culture medium and the liquid aqueous methanol-containing substrate under conditions of aerobic fermentation suitable for converting the fed methanol-containing substrate into organic stored-energy molecules; and - separating the organic stored-energy molecules from the microorganisms and / or the cell culture medium.