JP2005328849A - Anaerobic fermentation of carbon monoxide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a useful product by effective fermentation of waste gas containing carbon monoxide. <P>SOLUTION: A method for producing hydrogen comprises fermenting carbon monoxide through a bioreactor including anaerobic Bacillus smithlii and a nutrient medium. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is for producing products, materials, intermediates, etc., such as organic acids, single cell proteins (“SCP”), hydrogen, alcohols and salts of organic acids, from an industrial process waste gas stream. It is directed to biological methods, treatments, microorganisms and equipment, and more specifically to a method utilizing continuous gas substrate fermentation under anaerobic conditions to effect this conversion.

  A conventional method for producing organic acids, alcohols, hydrogen and salts of organic acids is chemical synthesis of petroleum-derived feedstocks. The rapidly rising price of oil has generated considerable interest in the production of these valuable supplies by fermentation, which can either be restored or use waste as a feedstock. Single cell proteins are produced as a byproduct of fermentation and used as animal feed supplements.

  There are also growing concerns about the huge amount of air pollutants and greenhouse gases produced by conventional industrial processes. The Environmental Protection Agency recently estimated that over 6 million tons of carbon monoxide and nearly 4 million tons of hydrogen were released by the industrial complex annually. This essential part of waste carbon monoxide and hydrogen, ie approximately 2.6 million tons of carbon monoxide and 500,000 tons of hydrogen, is the result of carbon black production and coke production. Large amounts of carbon monoxide or hydrogen are produced by the ammonia industry (125,144 tons of carbon monoxide in 1991), petroleum refining (8 tons per 1000 barrels), steel mills (152 pounds per ton of steel produced) and wood. Is also produced by sulfate pulping (286 pounds per ton of pulp). In 1991, the adipic acid industry produced 40,773 tons of carbon monoxide, which has been burned as a valuable or flammable fuel. In many cases, these gases are released directly into the atmosphere, placing a heavy burden on the environment.

  Typically, waste gas from the manufacture of industrial products is released at low pressure and low temperature. Current technology cannot utilize these diluent gases under these conditions. It would be expensive and impractical to adapt existing technologies to separate and recover hydrogen or carbon monoxide from these waste streams.

  In light of the foregoing, other than chemical synthesis of petroleum-derived feedstocks, production of products, materials, intermediates, etc., such as organic acids, alcohols, hydrogen and salts of organic acids, to utilize the above waste gas There is a need for cost effective and practical methods, microorganisms and equipment to do so.

  In accordance with the present invention, products, materials, intermediates, etc., such as organic acids, alcohols, hydrogen, single cell proteins and / or salts of organic acids can be used as waste carbon monoxide, hydrogen and / or industrial processes. Produced from carbon dioxide, thereby reducing environmental pollution while simultaneously saving energy and chemical feedstock.

  More specifically, the present invention provides an anaerobic Bacillus smithii bacterium that produces a fermentation product by anaerobic fermentation of carbon monoxide and a gas comprising carbon monoxide in a bioreactor containing a nutrient medium. There is provided a method for producing a fermented product, comprising a step of fermenting and a step of recovering a fermented product from a fermentation broth. In addition, ATCC No. which can be used in such a method. Also provided are biologically pure cultures of the microbial Bacillus smithii ERI-H2 strain having all of the identified characteristics of 55404 and mixed cultures containing the Bacillus smithii ERI-H2 strain (ATCC 55404) To do.

  According to an exemplary method of the present invention, the desired component of the dilution gas mixture contains one or more cultures of anaerobic bacteria that utilize the waste gas component by direct routes to produce the desired compound. Introduced into bioreactor. The compound is recovered from the aqueous phase in separate container (s) utilizing recovery methods suitable for the compound being produced. Examples of recovery methods include extraction, distillation or combinations thereof, or other efficient recovery methods. Bacteria are removed from the aqueous phase and recycled to avoid toxicity and maintain a high cell concentration, thus maximizing the reaction rate. Cell separation can be accomplished by centrifugation, membrane ultrafiltration or other techniques, if desired.

  According to the present invention, the production of organic acids, hydrogen, single cell proteins, alcohols and / or salts of organic acids, intermediates, materials, etc. from carbon monoxide, hydrogen and / or carbon dioxide. Methods and / or microorganisms can also be provided.

  In accordance with the present invention, also such as organic acids, alcohols, hydrogen, single cell proteins and / or salts from waste gas streams of industrial processes such as oil refining, carbon black, coke, ammonia and methanol production Methods, microorganisms and equipment for the production of items can also be provided.

  As used herein, the term “waste gas” or “waste gas stream” is mixed with compounds including other elements or gaseous carbon dioxide, nitrogen and methane, and typically By carbon monoxide and hydrogen released or exhausted to the atmosphere either directly or by combustion. Emission usually occurs at standard chimney temperatures and pressures. Thus, the method of the present invention is suitable for converting these air pollutants into useful products such as organic acids, alcohols and salts of organic acids. These products include but are not limited to acetic acid, propionic acid and butyric acid; methanol, ethanol, propanol and n-butanol; plus salts such as magnesium calcium acetate (CMA) and potassium acetate (KA) .

  Anaerobic bacteria known to convert carbon monoxide and water or hydrogen and carbon dioxide into alcohols and acids and acid salts include Acetobacterium kivui, A. et al. A. woodii, Clostridium aceticum, Butyribacterium methylotropicum, C.I. C. acetobutyricum, C.I. C. formaceticum, C.I. C. kluyveri, C.I. C. thermoaceticum, C.I. C. thermocellum, C.I. C. thermohydrosulfuricum, C.I. C. thermosaccharolyticum, Eubacterium limosum, C.I. Includes C. ljungdahlii PETC and Peptostreptococcus products. Anaerobic bacteria known to produce hydrogen from carbon monoxide and water include Rhodospirillum rubrum and Rhodopseudomonas gelatinosa.

More specifically, Acetobacterium kivui, Peptostreptococcus product, Acetobacterumumumium, Clostridium thermobacterium, Such bacterial species react:
4CO + 2H ₂ O → CH ₃ COOH + 2CO ₂ dG = −39 kcal / reaction (1) produces acetate.

Many anaerobic bacteria are also known to produce acetic acid from hydrogen and carbon dioxide. These bacterial isolates are A. A. kivui, P.A. Includes species of P. productus and Acetobacterium, which have the equation 4H ₂ + 2CO ₂ → CH ₃ COOH + 2H ₂ dG = −25 kJ / reaction (2)
Homoacetic acid fermentation is utilized by anaerobically oxidizing hydrogen and carbon dioxide according to

  Acetobacterium woodi and Acetoanaerobium noterae produce acetate from hydrogen and carbon dioxide according to the above reaction, but in addition to acetate, A. noterae produces some propionate and butyrate. Another chemoautotrophic bacterium, Clostridium aceticum, produces acetate from carbon dioxide using the glycine decarboxylase pathway.

  A. A. kivui, P.A. Products (P. producttus) and A. Some bacteria, such as A. woodii, produce acetate from either carbon monoxide and water or hydrogen and carbon dioxide. P. P. productus gives particularly fast conversion rates and is highly resistant to carbon monoxide; however, this organism shows preference according to equation (1) over equation (2) .

  In addition to these listed bacteria, two additional strains of Clostridia that produce acetic acid or ethanol from carbon monoxide and water or hydrogen and carbon dioxide have been isolated. One is the cocoon-shaped gram-positive non-thermophilic anaerobe Clostridium ljungdahlii ERI2, which provides excellent acetic acid yield and works at low pH which greatly enhances product recovery. C. C. ljungdahlii ERI2 performs an active acetic acid-producing fermentation of glucose. It also rarely forms spores and carries out fermentation of mainly monoacetic acid generation of hexose or water: carbon dioxide. It is pericymal flagella and is motile. C. referred to as ERI2. This new strain of C. ljungdhalii has been isolated from a natural water source, and the American Type Culture Collection (ATCC), Rockville, Maryland, December 8, 1992 (Accession number 55380).

  In the production of the products of the invention, the “mixed strains” of the bacteria listed above may be utilized. By mixed strain is meant a mixed culture of two or more anaerobic bacteria. This mixed strain, when used in the methods described herein, produces organic acids (such as acetic acid) or their salts, alcohol, hydrogen, SCP, and the like.

  In the development of the present invention, new strains of anaerobic bacteria have been isolated that perform this conversion with high efficiency. In addition, modifications to the fermentation conditions can result in the production of ethanol instead of acetic acid in some strains. Depending on the specific microorganism (s) utilized, the variables that must be considered in the formation of the product from the waste gas are nutrient components and concentrations, medium, pressure, temperature, gas flow rate, Liquid flow rate, reaction pH, stirring speed (when using a Continuously Stirred Tank Reactor), inoculation level, maximum substrate (gas introduced) concentration to avoid inhibition, and maximum to avoid inhibition Includes product concentration.

  According to an exemplary embodiment of the present invention and as shown in FIG. 1 of the drawings, the first stage of the conversion process is the preparation of a nutrient medium (10) for anaerobic bacteria. The content of the nutrient medium can vary based on the type of anaerobe utilized and the desired product. Nutrients may be continuously stirred (CSTR), immobilized cells (ICR), trickle bed (TBR), bubble columns, gas lift fermenters, or other suitable fermentation reactors. A bioreactor or fermenter (12) consisting of one or more vessels and / or towers of the type to be included is constantly fed. Within the bioreactor (12) there is an anaerobic bacterial culture of either single or mixed species utilized in the gas conversion process. For CTRS, TBR, bubble column, and gas lift fermenters, these bacteria live dispersed throughout the liquid phase of the reactor, but for ICR, the bacteria adhere to the inner packing medium. This packing medium must provide maximum surface area, high mass transfer rate, low pressure drop, uniform gas and liquid distribution, and plugging, clogging, nesting and wall channeling. channeling) should be minimized. Examples of such media materials are ceramic bar saddles, Raschig rings or other high performance packings.

  Waste gas (14) is continuously introduced into the bioreactor (12). The gas is retained in the bioreactor (12) for a period of time that maximizes the efficiency of this process. Exhaust gas (16) containing inert and unreacted substrate gas is then released. The liquid effluent (18) is advanced to a centrifuge, hollow fiber membrane or other filtration device (20) to separate the microorganisms carried in suspension. These microorganisms (22) are returned to the bioreactor (12) (cell recirculation) to maintain a high cell concentration resulting in a faster reaction rate.

  The next step in the method is the separation of the desired biologically produced product (s) from the permeate or centrifuge (24). In the embodiment depicted in FIG. 1, the permeate or centrifuge (24) is advanced to the extraction chamber (26) where it is contacted with the solvent (28). The solvent (28) should have a high partition coefficient for the desired end product, a high recovery factor, low toxicity to humans, low toxicity to bacteria, immiscibility with water, a suitably high boiling point and An emulsion should not be formed with the reactor components. Solute partitioning between the solvent and aqueous phase can determine the thermodynamic feasibility and the amount of solvent required to remove the final product. Typical solvents include secondary and tertiary amines in suitable solvents, tributyl phosphate, ethyl acetate, trioctyl phosphine oxide and related compounds in suitable co-solvents, long chain alcohols, hexane, cyclohexane, chloroform and tetrachloroethylene. .

  Nutrients and materials in the aqueous phase (30) are returned to the bioreactor (12) and the solvent / acid / water solution (32) proceeds to the distillation column (34) where it is removed from the acid and water (36) to the solvent (28 ) Is heated to a temperature sufficient to separate. The solvent (28) proceeds from the distillation column (34) through a cooling chamber (38) that reduces the temperature to the optimum temperature for extraction and then returns to the extraction chamber (26) for reuse. The acid and water solution (36) proceeds to the final distillation column (40), where the desired final product (42) is separated from the water and removed. Water (44) is recycled for nutrient preparation.

  FIG. 2 shows a method for producing road deicing agent, magnesium calcium acetate (CAM) (46) from waste gas (48). This method is identical to the acetic acid method of FIG. 1 by solvent extraction. That is, the same organism, nutrients and process conditions are used in a continuous fermentation involving the reaction vessel. Similarly, cell recirculation by hollow fiber membranes, centrifugation or other filtration devices is equally used in this method. Finally, extraction of acetic acid in the extraction chamber is used, followed by recycling of the medium without acid.

  After extraction, the CMA production method is very different from the acetic acid production method of FIG. In the CMA process, a solvent (50) containing acetic acid and a small amount of water is sent to a reaction vessel (52) for CMA production. The water content of the solvent stream depends on the solvent used for acetic acid extraction. Again, secondary and tertiary amines in suitable co-solvents, tributyl phosphate, ethyl acetate, trioctyl phosphine oxide and related compounds in suitable co-solvents, solvents such as long chain alcohols, hexane, cyclohexane, chloroform and tetrachloroethylene are used May be dictated by the results. The reaction vessel (52) for CMA is most suitably a Continuous Stirred Tank Reactor (CSTR), although other reactor systems may be used. A mixture (54) of bitter lime and magnesium oxide in water is added to the solvent containing acetic acid and water. The reaction occurs and produces CMA in an aqueous solution at or below the saturation level.

  CMA, water and solvent (56) are then sent to a settling device (58) to separate the water and solvent phases. The solvent phase (60) is returned to the extraction chamber for recycling. CMA / water (62) is sent to drying / pelleting (64) to produce a pelleted CMA product.

  Potassium acetate (KA) can be produced as an alternative product by using caustic potash (or potassium oxide) instead of bitter lime. Since KA is produced as a 50 percent aqueous solution, drying and pelleting is not required.

  FIG. 3 shows a method for producing ethanol from waste gas. As in FIG. 1, waste gas (66) and nutrients (68) are fed to a reactor (70) containing a culture of microorganisms. The reactor may be any of the types described above in the description of FIG. The organism used in the ethanol production process must be able to produce ethanol instead of acetic acid / acetate. In general, a low fermentation pH of 4.0-5.5 is required in conjunction with nutrient limitation. The bacteria listed above that can work at these reduced pH levels can be used in this method of ethanol production.

  Waste gas is fed to a reactor containing a culture of organisms capable of ethanol production along with the required nutrients. Ethanol is produced as a product in a manner similar to that in FIG. Cell recirculation (72) may be used to increase the cell concentration in the reactor, but this procedure is not required to make this process work. Permeate (74) from the cell recirculation device containing diluted ethanol in the medium is sent to distillation (76) where water (78) and ethanol (80) are separated. 95 percent ethanol exits from the top of the distillation column and water (consumed medium) exits from the bottom of the column. The spent medium is returned to the reactor as a water recycle. 95 percent ethanol is sent to the molecular sieve system (82) to produce absolute ethanol (84).

  Thus, according to the present invention, now not only reducing the consumption of valuable chemical feedstock, but also by gas substrate fermentation that removes dangerous air pollutants from many industrial waste gas streams, It is possible to produce valuable organic acids, alcohols or salts of organic acids. Conventional methods for biologically obtaining these chemicals were based on sugar fermentation.

  In the method described above, the method is preferably carried out at 1 atmospheric pressure or higher. Preferably it is carried out at a pressure of up to 30 atmospheres, more preferably up to 20 atmospheres and most preferably up to 15 atmospheres.

  The following specific examples are presented to illustrate but not limit the present invention. Unless otherwise indicated, all parts and percentages in the specification and claims are based on volume.

Example 1 Production of Acetic Acid from Carbon Black Waste Gas This example is directed to a method utilized to convert waste gas of a composition consistent with that of furnace exhaust for carbon black production to acetic acid. This waste gas has a composition of about 13 percent carbon monoxide, 14 percent hydrogen and 5 percent carbon dioxide, with the remaining 68 percent being nitrogen, mainly containing trace oxygen and sulfur compounds. This waste gas is produced as a result of partial oxidation of gas or oil with insufficient air to produce amorphous carbon, with approximately 1.2 pounds of carbon monoxide being produced per pound of elemental carbon. These waste gases create serious air pollution problems and also represent valuable chemical feedstock resources that are not currently recovered.

  In developing this method, two separate pathways for producing acetic acid from carbon black waste gas were studied. The direct route converts carbon monoxide and water or hydrogen and carbon dioxide directly to acetic acid according to equations (1) and (2), respectively. The indirect pathway involves water gas shift reaction followed by conversion of carbon monoxide and water to hydrogen and carbon dioxide by production of acetic acid from hydrogen and carbon dioxide. This indirect route has been found to be a smaller and more efficient use of the technology.

  The acetic acid sources tested are summarized in Table 1. Of these bacteria that produce acetic acid directly from carbon monoxide, A. A. kivui and the newly isolated strain C. C. ljungdahlii ERI2 exhibits a much superior rate for both carbon monoxide and hydrogen utilization. Further experiments proceeded using these two anaerobic bacteria.

  There are obvious advantages to bacteria that utilize carbon monoxide and hydrogen simultaneously. This provides the most efficient use of waste gas and is expected to remove the greatest amount of air pollutants.

Bench-scale operation of the described method for producing acetic acid As shown in FIG. 4 of the drawings, and in accordance with one aspect of the present invention, a bench-scale continuous conversion system is known as New Brunswick Scientific Company (New Brunswick). Scientific Co., Inc.), and is shown to include a BioFlo IIC fermenter (150) from Edison, NJ. The fermenter (150) is equipped with a stirring motor, pH controller, foam controller, thermostat, dissolved oxygen probe, nutrient pump and 2.5 L culture vessel. The working volume is variable (1.5-2.0 L). Other variable operating parameters include medium feed rate (dilution rate), gas flow rate (gas retention time), and agitation (rpm). The exhausted or exhaust gas exits the fermenter (150) through a water trap and sampling port and through a cooler fixed to the exhaust hood.

Culture medium (152) is recirculated through cross-flow hollow fiber module (154) by a peristaltic pump (from Cole Palmer). The recirculation rate is about 80-100 mL / min. The hollow fiber module (154) has the following characteristics; the surface area is 0.35 ft ² , the pore diameter is 0.2 μm, and the lumen diameter is 1 mm. The permeate (156) is pumped to the storage tank (158) (feed storage). Culture cells are returned to the fermentor along line (155).

  A counter-flow acetic acid extraction system including a two-stage mixer and settling components includes first and second mixers (160) and (162) and first and first settling tanks (164) and (166). To do. The permeate (168) from the storage (158) is pumped through the flow controller (170) to the mixer (160). Solvent (172) is pumped from solvent storage (174) to mixer (162) through flow controller (176). Both mixer (160) and mixer (162) are equipped with a stirring mechanism to achieve good mixing of the aqueous and solvent phases. Both phase mixtures from mixers (160) and (162) are directed to settlers (164) and (166), respectively. Phase separation is accomplished in the settler. The aqueous phase (178) from the settling device (164) is pumped to the mixer (162) and the solvent phase (180) from the settling device (164) is pumped to the separator (182). The aqueous phase (184) from (166) is pumped to the raffinate storage (186) and the solvent phase (188) from the settler (166) is pumped to the mixer (160). The raffinate is recycled to CSTR 50 along line (190). This recirculation line (190) is partially leached at (192) to remove the inhibitor.

  The acetic acid loaded solvent (180) is pumped through the preheater (196) to the distillation flask (194). The distillation flask (194) is equipped with two thermocouples (196) and (198) that monitor and control the temperature in the liquid and gas phases. The heating temperature for distillation is set to achieve maximum volatilization of acetic acid. Acetic acid vapor is condensed in the cooler (100) and collected in the flask (102). The stripped solvent (104) is pumped through the cooling coil (106) to the solvent storage (174).

A bench scale operation of the described method as illustrated in FIG. 4 was assembled in the laboratory and quantitative yields were determined under optimized conditions. The nutrient mixture supplied to the culture was as follows. That is, 1. Monopotassium phosphate 3.00 g / L
Dipotassium phosphate 3.00 g / L
Ammonium sulfate 6.00 g / L
Sodium chloride 6.00 g / L
Magnesium sulfate dihydrate 1.25g / L
1. 80.0 ml salt consisting of 1.0 g yeast extract3. 1.0 g of trypticase 4. 3.0 ml of PFN (Pfenning) trace metal solution ferrous chloride tetrahydrate 1500 mg
Zinc sulfate heptahydrate 100mg
Manganese chloride tetrahydrate 30mg
300mg boric acid
Cobalt chloride hexahydrate 200mg
Copper chloride monohydrate 10mg
Nickel chloride hexahydrate 20mg
Sodium molybdate dihydrate 30mg
Sodium selenate 10mg
1000ml distilled water
5). 10.0ml vitamin B pyridoxal hydrochloride 10mg
Riboflavin 50mg
Thiamine hydrochloride 50mg
Nicotinic acid 50mg
D-Calcium pantothenate 50mg
Lipoic acid 60mg
50 mg of p-aminobenzoic acid
Folic acid 20mg
Biotin 20mg
Cyanocobalamin 50mg
1000ml distilled water
6). 0.5 g of cysteine hydrochloride7. 0.06 g calcium chloride dihydrate8. 2.0 g of sodium bicarbonate9. 1.0 ml Resazurin (0.01%)
10. 920.0 ml of distilled water The nutrient solution was pH adjusted to 6.6 for use with A. kivui, while the new strain C.I. For C. ljungdahlii ERI2, the pH was adjusted to 4.9. The ability to work at lower pH is a major advantage in acetic acid recovery. This solution was then sparged for 20 minutes in an atmosphere of 20% carbon dioxide and 80% nitrogen, then transferred anaerobically and autoclaved for 15 minutes.

A number of experiments were performed in both a continuous stirred reactor (CSTR) and an immobilized cell reactor (ICR). The obtained results are illustrated in the following data. Bacterial strain A. A. kivui and C.I. CSTR experiment using C. ljungdahlii ERI2 CSTR and anaerobic bacteria C. ljungdahlii ERI2 and A.I. The bench scale system operating with A. kivui is from New Brunswick Scientific's BioFlo IIc fermenter, hollow fiber membrane unit for cell recycling and extraction and distillation columns. Made. The nutrient mixture was fed into the bioreactor at a rate of 3.2 cubic centimeters per minute. The reactor volume was 2.5 liters, of which a constant liquid level of 1.5 liters was maintained. The liquid was stirred at a variable speed up to 1000 revolutions per minute with gas introduced at a rate of approximately 500 cubic centimeters per minute. The optimum gas retention time was within 3 minutes. The gas supply fluctuated with its uptake by bacteria, which in turn was a function of cell density.

  The liquid from the bioreactor was advanced to the hollow fiber membrane at a rate of 55 to 70 milliliters per minute. From the hollow fiber membrane, permeate was collected at a rate of 1.5 milliliters per minute. This permeate analysis shows that the acetic acid / acetate concentration at this stage ranges over an excess of 20 grams per liter. When operated at a pH of 4.9, 42 percent of this product is C.I. It was in acid form using C. ljungdahlii ERI2. A. For A. kivui, the acid yield was only 1.4 percent. The results of various trials for two bacteria including conversion rate and product yield are summarized in Tables 2 and 3.

Bacterial strain C.I. ICR experiments utilizing C. ljungdahlii ERI2 From 2 inch OD x 24 inch high glass tubes filled with fabric to support cells and from Enkamat 7020 as immobilization medium An immobilized cell reactor (ICR) consisting of was also tested in the acetic acid production method. As an acetic acid-producing anaerobe, C.I. Using a C. ljungdahlii ERI2, 100 percent carbon monoxide and 79 percent hydrogen were converted with a gas retention time of 20 minutes. The acetic acid concentration in the removed liquid was approximately 6.0 grams per liter. The results of the ICR study are summarized in Table 4.

  ICR has certain appeal to an industrial scale in that the energy costs for operating the reactor are greatly reduced. Proper selection of packing material, solution phase and pressure can result in production approaching that of CSTR.

Acetic acid recovery Various solvents were tested for acetic acid recovery from permeate and the results are summarized in Table 5. Tributyl phosphate was identified as having both a high partition coefficient and a high boiling point. Solvent and permeate from the cell separator were mixed in a two-stage extraction process. Alternatively, an extraction column could be used. The permeate was introduced into a 3 liter flask where it was mixed with the incoming solvent. The ratio of 1 part solvent to 1 part permeate worked well and gave high recovery. The combined liquid is advanced from the mixer to a 4 liter settling chamber where the solvent / acetic acid mixture separates from water and nutrients as a lower density phase. A retention time of approximately 15 minutes was used in the settling tank. The lower density phase was extracted and fed to the distillation flask. The raffinate was advanced from the first settler to the second mixer where it was again contacted with the solvent and then removed from the second settling chamber. This allowed for a more complete extraction of acetic acid; acid recovery was increased from 82 percent to over 96 percent using tributyl phosphate. The solvent / acetic acid mixture from the settler was returned to the first mixer while water and organic raffinate were returned to the bioreactor.

  The distillation unit was a 5 liter flask with a boiling mantle. A common distillation column with reflux could be used for complete acid recovery. Due to the high boiling point of tributyl phosphate, almost complete recovery is achieved in one step. The solvent / acetic acid mixture was heated to 120 ° C. and acetic acid was collected at the top of the condenser coil. A distillation efficiency of 70 percent was achieved in this single stage system.

  Solvent mixtures were also tried, and the partition coefficients of the mixed solvents are summarized in Table 6.

Example 2 Production of acetic acid from carbon black waste gas Mass transfer in cell reactions at higher pressures can be further enhanced by operating the system at increased pressure. A simple batch experiment was performed to test the dynamics of this system. It was found that the reaction rate increased at a linear ratio to pressure with a corresponding decrease in effective retention time. Another advantage of operating at increased pressure is that the reactor volume can also be reduced in a linear fashion, i.e. operating at 10 atmospheres is one-tenth of a reactor operating at 1 atmosphere. It requires a reactor with a volume. Figures 5 and 6 show the increase in cell density and acetic acid concentration, respectively, at increased pressure. This acetic acid concentration far exceeds the typical batch concentration for a batch reactor at atmospheric pressure.

Example 3 Production of acetic acid from carbon black waste gas containing surfactant Mass transfer is also increased by the use of surfactant. Table 7 shows C.I. in the presence of various commercial surfactants. Figure 3 represents the results of a carbon monoxide uptake test performed at C. ljungdahlii ERI2. In each case, a control value of 100 (percent) represents the carbon monoxide uptake in batch fermentation and the sample value represents the percent of control in batch fermentation in the presence of detergent.

Table 1
About carbon monoxide, hydrogen and carbon dioxide conversion
Bacterial pathways tested Acetic acid-producing bacteria Single Bacterial Carbon and Hydrogen Consumption Direct Path Product None. Rimosum None A. None. C. Aceticum None C.I. Telmoseticum None Spheroides None A. Woody Yes A. Kibui Yes C.I. RJ Tungary ERI2 Yes Indirect route Geratinosa None Rubulum None

Example 4 Production of CMA from carbon black waste gas A carbon black waste gas containing about 14 percent carbon monoxide, 17 percent hydrogen and 4 percent carbon dioxide as the major components in nitrogen was converted to 6 atmospheres at 37 ° C. And is sparged into a 160 L continuous stirred tank reactor containing Clostridium rujungdalli isolate ER12, ATCC deposit 55380. Waste gas is produced as a result of partial oxidation of hydrocarbons with insufficient air to produce amorphous carbon, producing about 1.2 pounds of carbon monoxide per pound of elemental carbon. These waste gases create serious air pollution problems and also represent valuable chemical feedstock resources that are not currently being recovered. The gas retention time (defined as the ratio of reactor volume to gas flow rate at standard conditions) is maintained at 0.52 minutes. An aqueous liquid medium containing water, basic salts, vitamin Bs, nitrogen source and sulfide source is defined as a liquid dilution rate of 1.05 hours ⁻¹ (ratio of liquid flow rate to reactor volume). To the reactor. The stirring speed in this reactor is 322 rpm, the temperature is 37 ° C., and the operating pH is 5.03. Carbon monoxide conversion under these conditions was 83 percent and hydrogen conversion was 54 percent. A hollow fiber membrane cell recirculation unit was used to maintain a cell concentration of 10.5 g / L inside the reactor. The dilute acetic acid / acetate product stream from the reactor containing 13.2 g / L acetic acid / acetate is sent to a three-stage countercurrent extractor where it is extracted with a solvent. The ratio of solvent to feed is 1 to 4. Acetic acid in the acetic acid / acetate product stream is 3.7 g / L. The acetic acid concentration in the solvent leaving the extractor is 16.7 g / L. Water (medium) from the extraction is returned to the fermentor as recirculation.

The dolomite / magnesium oxide is added directly to acetic acid in the solvent phase to produce CMA. After the reaction, the saturated CMA solution is sent to drying and pelletizing to form 1.15 pounds of CMA containing a 3/7 molar ratio of Ca ²⁺ / Mg ²⁺ per pound of acetic acid.

Example 5 Production of acetic acid from carbon black waste gas Carbon black waste gas containing about 14 percent carbon monoxide, 17 percent hydrogen and 4 percent carbon dioxide in nitrogen was added at 1.58 atm, 37 ° C. And is sprinkled into a 144 L trickle bed reactor containing Clostridium rujungdalli isolate ERI2, ATCC deposit 55380. A trickle bed reactor is a column packed with a commercial packing such as a Raschig ring or a bar saddle, where liquid and gas are brought into contact with each other by the flow through the column. In this example, both liquid and gas enter the column from the top in a simultaneous fashion, although countercurrent (gas enters the bottom and liquid enters the top) is possible. The gas retention time is maintained at 0.46 minutes and the liquid medium dilution rate is 0.57 hours- ¹ . The liquid medium contains the same components as in Example 1. Agitation in the reactor is provided by liquid recycle using a recirculation rate of 60 gpm. The operating pH in the reactor is 5.05. The conversion of carbon monoxide under these conditions is 57 percent and the hydrogen conversion is 58 percent. A hollow fiber unit is used to maintain a cell concentration of 13.6 g / L inside the reactor.

  A dilute acetic acid / acetate product stream containing 6.4 g / L complex acetic acid / acetate and 2 g / L acetic acid is sent to a three-stage countercurrent extraction column. The ratio of solvent to feed is 1: 4. Acetic acid in the solvent leaving the reactor is 10 g / L. Water (medium) from the extraction unit is returned to the reactor as a recycle.

  The solvent containing acetic acid is sent to distillation to recover the acid and solvent. A vacuum solvent distillation column and an acetic acid distillation column are used in the separation. Glacial acetic acid is produced as the final product.

Example 6 Production of Potassium Acetate from Carbon Black Waste Gas The carbon black waste gas of Example 4 is used to make potassium acetate instead of CMA. All fermentation and solvent extraction conditions remain the same. Caustic potash (potassium oxide) is used to react with acetic acid to form a 50 percent solution of potassium acetate directly in the solvent phase.

Example 7 Production of SCP from Coke Oven Waste Gas Coke oven waste gas containing about 6 percent carbon monoxide, 2 percent carbon dioxide, 57 percent hydrogen, 5 percent nitrogen and 27 percent gaseous carbohydrates. And fed to a continuous stirred tank reactor with cell recirculation as previously described in Example 4. This reactor is used to produce products such as dilute acetic acid or ethanol. In addition, the cell concentration inside the reactor is 13.6 g / L. These cells (microorganisms) can be harvested to produce bacterial single cell proteins as animal feed. A purge stream from the reactor containing the cells is sent to the dryer to process the dried single cell protein.

Example 1 Production of Hydrogen from Refiner Waste Gas A refinery waste gas containing about 45 percent carbon monoxide, 50 percent hydrogen and 5 percent methane was introduced on March 18, 1993. American Type Culture Collection, 50 ° C. and several inches of water, containing Bacillus smithlii isolate ERIH2, deposited in Rockville, Maryland and given deposit number 55404 Sprinkle in a 1L CSTR running at The medium to the reactor is 1.0 g / L corn step liquor. Carbon monoxide in waste gas is converted to carbon dioxide and hydrogen together with water. At 90 percent conversion, the outlet gas stream contains 3.2 percent carbon monoxide, 64.4 percent hydrogen, 28.8 percent carbon dioxide and 3.6 percent methane. Carbon monoxide, carbon dioxide and methane are removed from the gas stream by solvent extraction.

Example 2 Production of other chemicals from carbon black waste gas A carbon black waste gas containing about 14 percent carbon monoxide, 17 percent hydrogen and 4 percent methane in nitrogen is heated to 37 ° C and several Sprinkle into a 1L CSTR operating at inch water pressure. The medium in the reactor is a basal salt mixture containing water, vitamin Bs, salts and minerals. Single or mixed cultures in the reactor produce liquid phase products of methanol, propanol, butanol, propionic acid, butyric acid or other desired products. This system is set up essentially the same as in Example 6. After dilution product formation, the product is recovered in a suitable product recovery system consisting of extraction, distillation or other known product recovery techniques. If multiple products are produced, a staged product recovery system is used.

  Thus, as a result of the present invention, there is provided a highly effective improved method for converting waste gas into salts of acids, alcohols, hydrogen, SCP or organic acids including organic acids such as acetic acid, thereby In particular, it can be recognized that the main purpose is fully realized. It is contemplated that modifications and / or changes can be made in the specifically described embodiments without departing from the invention and will be apparent to those skilled in the art from the preceding description and accompanying drawings. Accordingly, the foregoing description and accompanying drawings are merely illustrative of the preferred embodiments and are not restrictive, and the true spirit and scope of the present invention are defined in the appended claims. It is expressly intended to be determined by reference.

It is the schematic of the production method of acetic acid from waste gas. It is the schematic of the production method of CMA from waste gas. It is the schematic of the production method of ethanol from waste gas. 1 is a graphical representation of a continuous fermentation system according to an aspect of the present invention. 2 is an illustration of a graph of cell concentration versus time (OD). 2 is a graphical representation of acetic acid versus time (HAC).

Claims (5)

  ATCC No. Biologically pure culture of the microbial Bacillus smithii ERI-H2 strain having all of the identified properties of 55404.   A mixed culture containing Bacillus smithii ERI-H2 strain (ATCC 55404).   Fermenting a gas comprising carbon monoxide in a bioreactor containing an anaerobic Bacillus smithii bacterium and a nutrient medium that produces a fermentation product by anaerobic fermentation of carbon monoxide, and a fermentation product from the fermentation broth A method for producing a fermented product, comprising:   The method according to claim 3, wherein the fermentation product is hydrogen. The method according to claim 3, wherein the anaerobic bacterium is Bacillus smithii ERI-H2 strain (ATCC 55404).

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