United States Patent 19 (11) 4,197,421 Steinberg 45 Apr. 8, 1980

54 SYNTHETIC CARBONACEOUS FUELS AND 4,076,761 2/1978 Chang et al...... 260/676 R FEED STOCKS Primary Examiner-C. Davis (75) Inventor: Meyer Steinberg, Huntington Attorney, Agent, or Firm-R. V. Lupo; Leonard Belkin; Station, N.Y. Cornell D. Cornish 73 Assignee: The United States of America as 57 ABSTRACT represented by the United States This invention relates to the use of a three compartment Department of Energy, Washington, electrolytic cell in the production of synthetic carbona D.C. ceous fuels and chemical feedstocks such as gasoline, 21 Appl. No.: 934,765 methane and methanol by electrolyzing an aqueous sodium carbonate/bicarbonate solution, obtained from 22 Filed: Aug. 17, i978 scrubbing atmospheric carbon dioxide with an aqueous 51 Int. C.’...... CO7C 1/12 sodium hydroxide solution, whereby the hydrogen gen 52 U.S. Cl...... 585/733; 204/98; erated at the cathode and the carbon dioxide liberated in 204/101; 260/449.5 the center compartment are combined thermocatalyti 58) Field of Search ...... 260/676 R, 449.5; cally into methanol and gasoline blends. The oxygen 204/101,98; 585/733 generated at the anode is preferably vented into the 0. atmosphere, and the regenerated sodium hydroxide (56) References Cited produced at the cathode is reused for scrubbing the U.S. PATENT DOCUMENTS CO2 from the atmosphere. 3,519,488 7/1970 Gimer ...... 204/103 3,692,649 9/1972 Prigant et al...... 204/10 10 Claims, 1 Drawing Figure

NOOH 28 D- AIR'OUT

AIR'N' CA-SIC O (COIN ATM.) SCRUBBER

NUCLEAR ELECTRICAL POWER TURBO REACTOR GENERATOR

U FUEL.

CATALYTIC -30 DEHYDRATOR

32- (CH.)2n GASOLINE U.S. Patent Apr. 8, 1980 4,197,421

O2 EINITIOSV79)

„LOO,HIV?

„NI,HIV

4,197,421 2 mocatalytically combining the hydrogen and carbon SYNTHETIC CARBONACEOUS FUELS AND dioxide to form methanol which is thermocatalytically FEESTOCKS dehydrated to gasoline. More specifically, in the process of producing syn BACKGROUND OF THE INVENTION 5 thetic fuels and chemical feedstocks such as gasoline, This invention was made under, or during, the course methane and methanol which comprises converting a of, a contract with the U.S. Department of Energy. gaseous mixture of hydrogen and carbon dioxide to This invention relates to a process for producing methanol and then gasoline by thermocatalytic means; synthetic fuels and chemical feedstocks such as gaso the improvement which comprises electrolyzing an line, methane and methanol from gaseous CO2 and H2 10 aqueous sodium carbonate/bicarbonate solution in a by extracting CO2 from the air with a NaOH solution; three compartment electrolytic cell, said carbonate subjecting the resulting sodium carbonate solution to solution being obtained by scrubbing atmospheric car electrolysis in a three compartment electrolytic cell bon dioxide with an aqueous sodium hydroxide solu where hydrogen is formed at the cathode, oxygen at the tion, whereby the hydrogen generated at the cathode anode and CO2 is released in the center compartment; 15 and the carbon dioxide liberated in the center compart and combining the hydrogen and the CO2 ther ment are combined thermocatalytically into methanol mocatalytically to form gasoline. and gasoline blends. Raw synthesis gas containing hydrogen and carbon oxide and/or carbon dioxide useful in the synthesis of PRIOR ART methanol, methane, and gasoline are normally obtained 20 Electrolysis of electrolytic solutions in three com from the conversion of coal and other hydrocarbons by partment cells is generally known, as disclosed in U.S. a variety of known methods. The resultant synthesis gas contains impurities such as sulfur compounds, nitrogen Pat. No. 1,126,627 wherein an alkali chloride solution is compounds, particulate matter, etc., which require puri electrolyzed into NaOH and HCl; U.S. Pat. No. fication prior to its utilization in gasoline synthesis. 25 3,017,338 wherein a high purity alkali metal hydroxide It has now been found that instant invention utilizes and halogen is obtained from an alkali metal halide the atmosphere as a source of the oxides of carbon (CO solution; and U.S. Pat. No. 3,135,673 wherein an acid and CO2), from which pure CO2 is recovered in a three salt such as sodium bisulfate is recovered from the compartment electrolytic cell together with electrolytic ancie and sodium hydroxide is recovered at the cath H2 to produce synthetic fuels. 30 ode when feeding a nearly saturated sodium sulfate The advantages of using atmospheric CO2 as a source solution into the center compartment. This patent also for the synthesis gas in the synthesis of gasoline are discloses that the sodium hydroxide catholyte is con multifold. ducted to a scrubbing apparatus wherein the carbon A vast natural resource is readily available. A desir dioxide from the atmosphere is absorbed by said caustic, able CO2 balance between the biosphere and the atmo 35 forming a sodium carbonate solution which is combined sphere can be maintained by the removal of the CO2 with an equivalent amount of the anolyte effluent so from the atmosphere. A pure CO2 gas and H2 gas is dium bisulfate to regenerate the original sodium sulfate obtained from the electrolytic cell for use in the synthe which can be recycled to the electrolytic cell. sis of carbonaceous fuel. The atmospheric CO2 provides The removal of CO2 from gas streams, such as the an alternate and extended supply of premium synthetic atmosphere, by intimate contact with, and absorption carbonaceous fuel for this country thus advancing the into a solution of a strong base such as sodium hydrox goal of energy self-sufficiency. It would eliminate many ide whereby sodium carbonate is formed, and the regen environmental and safety problems inherent in fossil eration of said spent absorbent in a two compartment fuel utilization. It is more economical. electrolytic cell, using said sodium carbonate as an elec Accordingly, it is a primary object of instant inven 45 trolyte, is also well known in the prior art, as disclosed tion to provide a process for extracting CO2 from the in U.S. Pat. Nos. 3,519,488 and 3,692,649. However, atmosphere and combining this with electrolytic hydro both of aforesaid patents require the presence of sub gen to produce synthetic gas and gasoline. stantial amounts of a salt in addition to the alkali metal Another object of instant invention is to provide a hydroxide in the scrubbing solution. For example, U.S. process for extracting CO2 from the atmosphere with 50 Pat. No. 3,519,488 uses solutions of potassium hydrox sodium hydroxide, and electrolytically decomposing ide and potassium carbonate and U.S. Pat. No. the resulting sodium carbonate solution into the con 3,692,649 uses inert salts such as NaClO4, KCH3CO2, commitant generation of hydrogen and the release of NaCH3CO2, NaCl, KCl, Na2SO4 and K2SO4, together concentrated CO2 which are then thermocatalytically with the alkali metal hydroxide base. U.S. Pat. No. combined to form gasoline. 55 3,519,488 further adds a neutral electrolyte such as KF Still another object is to provide a three compartment or K2SO4 to the anolyte soltion to overcome problems sodium carbonate electrolysis cell for the concommitant encountered in the electrolysis of the spent scrubbing production of CO2 and hydrogen. solution containing the alkali metal carbonate. Accordingly, instant invention relates to a process of Other patents which disclose a two compartment producing synthetic fuels and chemical feedstocks such 60 electrolytic cell containing an alkali metal carbonate as gasoline, methane and methanol from atmospheric electrolyte useful in the collection and concentration of carbon dioxide which comprises extracting atmospheric carbon dioxide are U.S. Pat. Nos. 3,401,100 and CO2 from the air with an aqueous sodium hydroxide 3,494,842. solution whereby a sodium carbonate solution is Although the prior art discloses a three compartment formed; electrolyzing said sodium carbonate solution in 65 electrolytic cell generally, and U.S. Pat. No. 3,135,673 a three compartment electrolytic cell whereby hydro discloses a three compartment cell containing sodium gen is formed at the cathode, oxygen at the anode and carbonate as the partial electrolyte together with the CO2 is released in the center compartment; and ther bisulfate, the recovery of CO2 in the center compart 4,197,421 3 4. ment for combination with the hydrogen released at the vantages of both aforesaid processes, thereby reducing cathode as in instant invention is not disclosed. These capital and operating costs. patents only disclose the formation of an acid anolyte This electrolytic carbonate system may also be used and a basic catholyte with unreacted salt in the center for stack gas scrubbing of CO2. However, in this case compartment. where CO2 gas compositions up to 15% are available Similarly, although the prior art discloses the extrac compared to 0.035% in the atmosphere, adoption of a tion of CO2 from the atmosphere with a sodium hydrox conventional absorption/stripping technique may be ide solution whereby sodium carbonate is formed, and more economical. the regeneration of the sodium hydroxide in an electro The FIGURE shows by way of example a flow sheet chemical cell, the simultaneous liberation of CO2 and 10 of the process according to this invention with a dia hydrogen as in instant invention is not disclosed. grammatic representation of the three compartment Furthermore, there is no recognition in the prior art electrolytic cell. that CO2 from the atmosphere can be utilized in the A gas stream containing atmospheric CO2 is fed to a formation of a sodium carbonate electrolyte for a three caustic air scrubber 10 containing an aqueous NaOH compartment electrolytic cell capable of producing a 15 solution containing about 5 to 25% NaOH and at ambi substantially pure synthesis gas for the production of ent temperatures of about 10-25 C., wherein Na2CO3 synthetic fuel. The use of conventional synthesis gas is formed in accordance with the following reaction: obtained from coal, shale oil and other carbonaceous feedstocks containing hydrogen and carbon dioxide in the production of methanol and gasoline is well known 20 2NaOH + CO2 alties Na2CO3 + H2O in the art as disclosed by U.S. Pat. Nos. 3,950,369; 4,065,483; and 4,076,761. However, aforesaid synthesis The resulting sodium carbonate solution is conveyed gases are impure, and require purification steps which via line 11 to the center compartment 12 of a three are costly and time-consuming. compartment electrolytic cell 13 provided with an 25 anode compartment 14 and a cathode compartment 15, DESCRIPTION OF THE INVENTION and a suitable anode and cathode respectively (not The process, according to this invention, depends on shown), said anode compartment 14 being separated the electrolytic decomposition of water containing from the center compartment 12 by means of a hydrau higher concentrations of carbonate/bicarbonate ion, lically permeable non-permselective diaphragm 16 or which is essentially the electrolytic decomposition of 30 an anion-permselective membrane 16, and said cathode sodium carbonate/bicarbonate thus forming caustic, compartment 15 being separated from said center com H2, O2 and CO2. partment 12 by means of a cation-permselective mem brane 17. About 50% of the Na2CO3 exists in the form of NaHCO3 in the electrolytic cell as shown by the Na2CO3 + 4H2O electrolysis G 1. 35 following equation: 2NaOH + 3H2 + 3/2 O2 + CO2 CO2 - Na2CO3 + H2O)2NaHCO3 It has been found that water can be electrolytically decomposed to H2 and O2 in a sodium carbonate/bicar The construction of electrolytic cell 13 is known in the bonate cell releasing CO2 in addition to O2 at the anode art as described in U.S. Pat. No. 3,135,673 which is and H2 at the cathode. The theoretical cell voltage is incorporated herein by reference. The electrolytic cell approximately 3.0 volts per mole. of H2. This compares is operated at 3 to 3.5 volts and a current of 200 to 700 to 2.4 volts for the decomposition of water. However, if amp/sq.ft. and at a temperature below the boiling point a three compartment cell is used, the CO2 can be sepa of the electrolyte, such as about 25°-60° C. However, rated in a center compartment. Referring to the flow 45 when this cell is operated under pressure to coincide sheet in the FIGURE, the regenerated caustic is then with the operating conditions of the catalytic conver used to scrub the CO2 from the atmosphere and the tors so as to eliminate compression, temperatures of CO2 recovered from the cell is combined, with hydro about 100-150° C. are utilized. Although the diagram gen catalytically to form methanol and gasoline blends. 50 illustrates a single electrolytic cell, it is understood that In this case, the oxygen is vented to the atmosphere. It a multiple cell structure is utilized, wherein the cells are may also be possible to operate the carbonate cells connected in series. Pure gaseous hydrogen is removed under pressure to match the operating conditions of the from the cathode compartment 15 via exit pipe 18 and catalytic convertors so as to eliminate compression. The pure CO2 gas is released from center compartment 12 cell may be operated at elevated temperature 55 via exit pipe 19, and both are fed directly via line 20 to (100-150° C) to improve efficiency when under pres a catalytic convertor 21 of any conventional design and sure. The system, however, is essentially an isothermal containing a copper catalyst or other suitable catalyst, one for removal and recovery of CO2 compared to the wherein methanol and water are formed in accordance absorption-stripping process utilizing dilute potassium with the following reaction: carbonate which is slow to absorb atmospheric CO2 and requires stripping by means of heat exchange and distill tavti ing at high temperature. Furthermore, no additional cell 3H2 + CO2 Eise CH3OH + H2O equipment, power requirement and corrosion problems are encountered as existed in the use of electrolytic The water is removed from said convertor 21 via exit sodium chloride cells which produced caustic for CO2 65 line 22 and recycled via lines 23 and 24 into electrolytic scrubbing and the chlorine for neutralizing the sodium cell 13. It is preferable to recycle the water to line 11 carbonate formed. The use in instant invention, of a and mix directly with the carbonate electrolyte prior to sodium carbonate electrolytic cell eliminates the disad its introduction into electrolytic cell 13. Sodium hy 4,197,421 5 6 droxide is removed from cathode compartment 15 via the anode 1.52 lbs oxygen is released and vented to the exit line 25 which is recycled via line 26 into the caustic atmosphere. In the center compartment the 1.38 lbs of air scrubber 10 for reuse. Some non-critical amounts of CO2 is released. The purified recovered H2 and the CO2 sodium carbonate may remain mixed with the recycled are collected, compressed to between 50 and 100 atm, sodium hydroxide without affecting the function of the and heated to 350° C. over a copper catalyst where 1 lb subject invention. Oxygen gas is vented into the atmo of methanol is produced. The methanol can be further sphere from anode compartment 14 via exit 27. The air dehydrated over a zeolite catalyst at 350° C., and 100 depleted of its CO2 content is vented from air scrubber atm to a gasoline distillate weighing 0.45 lbs. The latter 10 via outlet line 28. two processes are well known in the art. The methanol formed in convertor 21 is conveyed via 10 Instant novel process of converting CO2 from the line 29 to a catalytic dehydrator 30 of conventional atmosphere to synthetic methanol and synthetic carbo design and containing a zeolite catalyst, to produce naceous fuels with electrolytically generated hydrogen gasoline and water in accordance with the following and oxygen in a three compartment carbonate electro reaction: lytic cell is a continuous, cyclic, efficient and economi 15 cal process. The use of air and water as the starting catalytic materials eliminates impurities, and the use of a carbon nCH3OH ine (CH2) + n2O ate electrolytic cell in lieu of the prior art bisulfate cell The water is withdrawn via line 31 and is also recycled or sodium chloride cell eliminates corrosion problems and fed into electrolytic cell 13, preferably by first mix and contaminants which would poison the copper cata ing directly with the carbonate electrolyte, and the lyst component used in the methanol synthesis. Since gasoline fraction is withdrawn via exit 32. Reactions 3 the removal and recovery of CO2 in a carbonate electro and 4 are exothermic and do not require any energy lytic cell is an isothermal process, no heating is neces input. sary and there is no pressure drop nor a large loss in The electrolytic carbonate cell 13 may be powered 25 heat exchange. This system is also adaptable to the by any electrical source of D. C. power. However, the production of methane by merely adding one additional most economical source of power is a nuclear power mole of hydrogen to the catalytic convertor. The recy reactor which powers an electrical turbo generator cling of the sodium hydroxide and the water for reuse in which supplies the direct current needed for the elec this process eliminates waste and renders this process trolysis of the sodium carbonate/bicarbonate cell. 30 particularly desirable for economic and efficiency rea The three compartment sodium carbonate/bicarbon SOS ate electrolytic cell operates at about 3 to 3.5 volts and The applications of this process can be very broad. at a current density of about 200 to 700 amp/sq.ft. to For example, this process can be used in the production effect decomposition of the carbonate solution into 3 of synthetic fuels at sea aboard nuclear aircraft carriers moles hydrogen, 3/2 moles oxygen, l mole carbon diox 35 using nuclear power, air and sea water. This jet fuel can ide and 2 moles sodium hydroxide, in accordance with be utilized by aircraft. reaction 1. The molar ratio of 3:1 of the hydrogen gas to I claim: the carbon dioxide gas released in this electrolysis reac 1. In the process of producing synthetic fuels and tion coincides with the molar ratio needed for the cata chemical feedstocks such as gasoline, methane and lytic reaction to produce methanol as shown in reaction methanol by converting a gaseous mixture of hydrogen 3. If it is desired to produce methane in lieu of methanol, and carbon dioxide to methanol and then gasoline by the molar ratio of the reactants hydrogen to carbon thermocatalytic means; the improvement which com dioxide is 4:1, requiring the addition of one mole hydro prises extracting atmospheric carbon dioxide with an gen to the catalytic convertor. aqueous sodium hydroxide solution to form a carbonate This process is applicable to atmospheric gas streams 45 solution, electrolyzing said aqueous sodium carbonate/- containing dilute amounts of CO2 such as 0.035% by bicarbonate solution in a three compartment electro volume of CO2 normally found in the atmosphere and lytic cell to generate pure hydrogen at the cathode and up to a maximum of 20% by volume of CO2 found in pure carbon dioxide in the center compartment, and stack gas emissions from the burning of fossil fuel. combining said pure hydrogen gas with said pure car The following example is merely illustrative of pres 50 bon dioxide gas thermocatalytically to form methanol ent invention and is not to be construed as limited and gasoline blends. thereto. 2. A process according to claim , wherein oxygen EXAMPLE generated at the anode is vented into the atmosphere. A 10% caustic solution containing about 2.5 lbs of 55 3. A process according to claim 1, wherein the so NaOH is used to counter-currently scrub the carbon dium hydroxide is regenerated at the cathode. dioxide from the atmosphere in a packed column at 4. A process according to claim3, wherein the regen ambient temperatures (about 25 C.). About 43,000 cu ft erated sodium hydroxide is recycled to scrub carbon of air is used. In this manner 1.38 lb of CO2 is scrubbed dioxide from the atmosphere. from the atmosphere which has a concentration of 350 60 5. A process according to claim , wherein the water parts per million by volume. About 80% of the CO2 is of reaction resulting from the catalytic conversion of recovered from the air. The resulting sodium car the gaseous mixture of hydrogen and carbon dioxide bonate/bicarbonate solution is sent to a 3 compartment into methanol and then gasoline, is recycled to the three electrolysis cell at a temperture below boiling such as compartment electrolytic cell. about 25°-60° C., where a D. C. electric current of 3 to 65 6. A process according to claim 1, wherein the three 3.5 volts and a current of 200-700 amp/sq.ft. decom compartment electrolytic cell operates all about 3 to 3.5 poses the carbonate solution. In the cathode compart volts and a current density of about 200 to 700 ment H2 is released and 0.19 lbs of H2 is collected. At amps/sq.ft. 4,197,421 7 8 7. A process in accordance with claim 1, wherein the aqueous sodium hydroxide solution contains about atmospheric gas stream may contain 0.035% to 20% by 5-25% sodium hydroxide. volume of carbon dioxide. 10. A process in accordance with claim 1, wherein 8. A process in accordance with claim 1, which is a the electrolytic cell is operated below the boiling point continuous process. 5 of the electrolyte. 9. A process in accordance with claim 1, wherein the it is k is is

O

15

20

25

30

35

s 45

SO

55

65