Method for preparing isopropyl alcohol (IPA) from carbon dioxide

Abstract

Disclosed is a method for preparing pure isopropyl alcohol (IPA) from carbon dioxide and water. Preferably, the method comprises the steps of: 1) subjecting the carbon dioxide to first electroreductio

Description

METHOD FOR PREPARING PURE ISOPROPYL ALCOHOL (IPA) FROM CARBON DIOXIDE TECHNICAL FIELD

[0001] The present disclosure belongs to the technical field of new energy chemical technology, and relates to a synthesis route for preparing pure isopropyl alcohol (IPA) from carbon dioxide. The synthesis route couples several processes of two-step electrolysis of the carbon dioxide, ketonization of acetic acid, and electroreduction of acetone, and is clean and economical without relying on fossil energy. BACKGROUND

[0002] The heavy dependence and consumption of fossil fuels in the development of human society causes excessive emissions of carbon dioxide and thereby triggers a series of environmental problems such as global warming on the one hand, and causes energy shortages on the other hand. Therefore, it is imperative to reduce carbon dioxide emissions and adjust the energy structure. It is an effective solution to reduce carbon emissions and open up new paths for chemical synthesis by using clean electricity generated from sustainable energy to convert excess carbon dioxide into high value-added chemicals. However, the types of products obtained from the electroreduction of carbon dioxide are limited, while the manufacture of many important chemical products relies heavily on fossil energy and is accompanied by serious carbon emissions. In view of this, further utilization of the products from electroreduction of carbon dioxide is of great interest for the synthesis of fossil fuel-derived chemicals.

[0003] Isopropyl alcohol (IPA), as an important bulk chemical, especially a raw material or an organic solvent in chemical synthesis, has been widely used, which has desirable economic benefits and occupies a huge market share. Especially after COVID-19, the expansion for production of the IPA, a type of medical disinfectant, has attracted widespread attention. A preparation process of the IPA is mainly based on propylene hydration. Direct hydration requires a high-temperature and high- pressure environment. However, this process has a low single-pass conversion rate of raw materials and high requirements for the purity of raw material propylene (99.5%) during synthesizing the IPA, which greatly limit the expansion of production scale and increase the dependence on fossil fuel propylene. Moreover, an additional consumption caused by the purification and concentration of propylene also makes this process extremely costly, and more stringent production conditions are required to further improve the conversion efficiency. Indirect hydration is to esterify propylene with sulfuric acid, and a resulting IPA sulfate is hydrolyzed to obtain IPA. This process has low requirements for the purity of propylene, a wider range of available raw materials, and a greatly- improved single-pass conversion rate of propylene, thus reducing refining costs. However, this process requires the consumption of a large amount of highly-corrosive concentrated sulfuric acid, which has production safety issues and can seriously corrode the production equipment. Moreover, a large amount of waste acid with a high concentration may be produced after the hydrolysis of isopropyl ester, cannot be directly discharged into the environment, and can increase the cost due to recovery and concentration. In addition, both the above two hydration processes are based on the propylene and rely on fossil fuels, and thus limits the expansion of production scale for IPA to a certain extent. Hydrogenation reduction of acetone (by thermal and / or electrical approaches) could also be used to produce IPA. However, considering that the current mainstream production methods of acetone still rely on fossil fuels (propylene and benzene), we began to explore the possibility of preparing acetone from carbon dioxide. To this end, a process is designed that combines the two- step electrolysis of CO and the ketonization of acetic acid, including: subjecting the carbon dioxide to electroreduction to obtain carbon monoxide, subjecting the carbon monoxide to electroreduction to obtain acetic acid or an acetate, and then subjecting the acetic acid or the acetate to ketonization of carboxylic acid (a kind of chemical catalytic process ) to obtain acetone, and subjecting the acetone prepared above to electrochemical hydrogenation to obtain IPA. This synthesis route is expected to enable the relatively gentle synthesis of IPA (an important chemical raw material) form carbon dioxide, by using clean electricity generated by sustainable energy without relying on any fossil fuels or petrochemical processes. Meanwhile, considering that there are many steps in this synthesis route, it may be beneficial to improving the economic benefits of the overall solution via directly synthesizing pure products to reduce separation costs. SUMMARY

[0004] In view of this, the present disclosure aims to provide a method for preparing pure IPA from carbon dioxide. In the present disclosure, the method for preparing pure IPA is performed by coupling four processes of two-step electrolysis of carbon dioxide, ketonization of carboxylic acid, and electroreduction of acetone, achieving a mild, green, and clean conversion of the carbon dioxide into pure IPA. This method is expected to be applied to the large-scale production and on- site preparation of IPA under the framework of new energy structures, without relying on any fossil energy.

[0005] To achieve the above object, the present disclosure provides the following technical solutions.

[0006] The method for preparing pure isopropyl alcohol (IPA) from carbon dioxide includes four steps of: two-step electrolysis of carbon dioxide, ketonization of carboxylic acid, and electroreduction of acetone. In order to reduce a separation cost, an intermediate obtained in each step of the method could be directly used as a raw material in the next step. The method has a schematic route diagram as shown in FIG. 1.

[0007] The present disclosure provides a method for preparing pure IPA from carbon dioxide, including the following steps:

[0008] step 1: subjecting carbon dioxide to first electroreduction to obtain carbon monoxide by using an anion exchange membrane-based membrane electrode reactor equipped with accessories under the action of a first catalyst at ambient temperature and ambient pressure, where a purity of the carbon monoxide obtained after the first electroreduction does not affect subsequent steps;

[0009] step 2: subjecting the carbon monoxide to second electroreduction to obtain an acetic acid (or acetate) aqueous solution by using a solid electrolyte-based membrane electrode reactor equipped with accessories under the action of a second catalyst at ambient temperature and ambient pressure, where a purity of the pure acetic acid aqueous solution obtained after the second electroreduction does not affect subsequent steps;

[0010] step 3: subjecting the pure acetic acid aqueous solution or the acetate to ketonization to obtain acetone by using a fixed bed reactor equipped with accessories under the action of a third catalyst at a certain temperature and ambient pressure; and

[0011] step 4: subjecting the acetone to third electroreduction to obtain pure IPA by using a bipolar membrane-based membrane electrode reactor equipped with accessories under the action of a fourth catalyst without introducing other impurities.

[0012] In some embodiments, the anion exchange membrane-based membrane electrode reactor in step 1 includes a cathode membrane, an anion exchange membrane, and an anode membrane that are laminated in sequence, a schematic structure of which is shown in FIG. 2.

[0013] In some embodiments, the cathode membrane is provided with the first catalyst, which is one or more selected from but not limited to the group consisting of nickel single atom-nitrogen- doped activated carbon, iron single atom-nitrogen-doped activated carbon, a cobalt phthalocyanine (CoPc) molecule, a commercial zinc oxide nanoparticle, a commercial nano-gold powder, and a commercial nano-silver powder.

[0014] In some embodiments, the anion exchange membrane is one or more selected from the group consisting of Fumapem FAA-3-50, Sustainion X37-50 RT, and Sustainion X37-FA.

[0015] In some embodiments, the anode membrane is prepared from a material being one or more selected from the group consisting of iridium oxide, ruthenium oxide, nickel foam, metal iridium / ruthenium, and a layered iron-nickel bimetallic hydroxide.

[0016] In some embodiments, the solid electrolyte-based membrane electrode reactor further includes a cathode shell having a first groove and an anode shell having a second groove;

[0017] the cathode shell having a first groove and the anode shell having a second groove are fitted and fixed to form a sealed structure:

[0018] a sealing gasket is arranged between an edge outside the first groove of the cathode shell and an edge outside the second groove of the anode shell;

[0019] the cathode membrane is arranged in the first groove of the cathode shell;

[0020] the cathode shell is provided with a carbon dioxide inlet and a carbon dioxide outlet;

[0021] the carbon dioxide outlet is connected with an absorption bottle containing one or more selected from the group consisting of a potassium hydroxide solution, a sodium hydroxide solution, a lithium hydroxide solution, and an ammonium hydroxide solution, to absorb incompletely converted carbon dioxide;

[0022] the anode membrane is arranged in the second groove of the anode shell;

[0023] the anode shell is provided with an anolyte inlet and an anolyte outlet; and

[0024] the anolyte is one or more selected from the group consisting of a sulfuric acid solution, a perchloric acid solution, phosphoric acid, sodium hydroxide, and potassium hydroxide.

[0025] In some embodiments, step 1 is conducted as the following parameters: the carbon dioxide is introduced at a flow rate of 5 standard cubic centimeters per minute (sccm) to 100 sccm, the first catalyst on an electrode is loaded at 0.5 mg / cm? to 2 mg / cm? the anion exchange membrane-based membrane electrode reactor is applied with a voltage of 1.8 V to 3.0 V, and an anolyte is at a flow rate of 30 mL / h to 600 mL / h.

[0026] In further embodiments, step 1 is conducted as the following parameters: the carbon dioxide is introduced at a flow rate of 40 sccm to 60 sccm, the first catalyst on the electrode is loaded at 0.8 mg / cm? to 1.2 mg / cm?, the anion exchange membrane-based membrane electrode reactor is applied with a voltage of 2.4 V to 2.6 V, and the anolyte is at a flow rate of 50 mL / h to 100 mL / h.

[0027] In some embodiments, the solid electrolyte-based membrane electrode reactor in step 2 includes a cathode membrane, an anion exchange membrane, and an anode membrane that are laminated in sequence, a schematic structure of which is shown in FIG. 3 and includes:

[0028] a cathode membrane;

[0029] an anion exchange membrane attached to the cathode membrane;

[0030] a solid electrolyte layer attached to the anion exchange membrane;

[0031] a cation exchange membrane attached to the solid electrolyte layer; and

[0032] an anode membrane attached to the cation exchange membrane.

[0033] In some embodiments, subjecting the carbon monoxide to second electroreduction includes subjecting the carbon monoxide to second electroreduction to obtain an acetic acid aqueous solution.

[0034] In some embodiments, the cathode membrane is provided with the second catalyst, which is one or more selected from but not limited to the group consisting of a copper gel, a heterogeneous metal atom-doped copper gel, a copper nanocube, a copper nanosheet, a copper nanowire, a copper multilayer spherical shell, a copper particle-modified carbon material, and a commercial nano- copper powder.

[0035] In some embodiment, the anion exchange membrane is one or more selected from the group consisting of Fumapem FAA-3-50, Sustainion X37-50 RT, and Sustainion X37-FA.

[0036] In some embodiments, the solid electrolyte layer is prepared from a material being one or more selected from the group consisting of a styrene-divinylbenzene copolymer, CsxH3xPW12040, a ceramic, and a 10 wt.% H3POu / polyvinylpyrrolidone (PVP) gel.

[0037] In some embodiment, the cation exchange membrane is prepared from a material being one or more selected from the group consisting of Nafion 115, Nafion 117, Nafion N212, and Nafion 1110.

[0038] In some embodiment, the anode membrane is prepared from a material being one or more selected from the group consisting of iridium oxide, ruthenium oxide, nickel foam, metal iridium / ruthenium, and a layered iron-nickel bimetallic hydroxide;

[0039] In some embodiments, the solid electrolyte-based membrane electrode reactor further includes a cathode shell having a first groove, the solid electrolyte layer frame and an anode shell having a second groove;

[0040] the cathode shell having a first groove, the solid electrolyte layer frame and the anode shell having a second groove are fitted and fixed to form a sealed structure;

[0041] a sealing gasket is arranged between an edge outside the first groove of the cathode shell and the solid electrolyte layer frame;

[0042] another sealing gasket is arranged between the solid electrolyte layer frame and an edge outside the second groove of the anode shell;

[0043] the cathode membrane is arranged in the first groove of the cathode shell;

[0044] the cathode shell is provided with a carbon dioxide inlet and a carbon dioxide outlet;

[0045] the solid clectrolyte layer frame is provided with an air and / or water inlet and a formic acid and / or formic acid aqueous solution outlet;

[0046] the anode membrane is arranged in the second groove of the anode shell;

[0047] the anode shell is provided with an anolyte inlet and an anolyte outlet; and

[0048] the anolyte is one or more selected from the group consisting of a sulfuric acid solution, a perchloric acid solution, phosphoric acid, sodium hydroxide, and potassium hydroxide.

[0049] In some embodiments, step 2 is conducted under the following condition parameters: the carbon monoxide is introduced at a flow rate of 5 sccm to 100 sccm, the second catalyst on an electrode is loaded at 0.5 mg / cm? to 2 mg / cm? the solid electrolyte-based membrane electrode reactor is applied with a voltage of 2.0 V to 3.0 V, deionized water that carries the acetic acid has a flow rate of 10 mL / h to 60 mL / h, and an anolyte has a flow rate of 30 mL / h to 600 mL / h.

[0050] In further embodiments, step 2 is conducted under the following condition parameters: the carbon monoxide is introduced at a flow rate of 40 sccm to 60 sccm, the second catalyst on the electrode is loaded at 0.8 mg / cm? to 1.2 mg / cm? the solid electrolyte-based membrane electrode reactor is applied with a voltage of 2.7 V to 2.8 V, deionized water that carries the acetic acid has a flow rate of 40 mL / h to 50 mL / h, and the anolyte has a flow rate of 50 mL / h to 100 mL / h.

[0051] In some embodiments, the fixed bed reactor for the ketonization of the acetic acid in step 3 includes a feed port, a catalytic chamber, a gas outlet, and a cold trap, a schematic structure of which is shown in FIG. 4.

[0052] In some embodiments, the ketonization of acetic acid refers to converting acetic acid into acetone and carbon dioxide at a temperature of 280°C to 350°C, preferably 290°C to 310°C.

[0053] In some embodiments, a carrier gas being one or more selected from the group consisting of argon, nitrogen, and helium is introduced into the feed port; the carrier gas passes through the acetic acid aqueous solution to carry acetic acid vapor into the catalytic chamber; the carrier gas has a flow rate of 5 sccm to 30 sccm, preferably 10 sccm to 20 sccm; and the acetic acid aqueous solution has a mass concentration of 500 ppm to 3,000 ppm, preferably 1,500 ppm to 2,500 ppm;

[0054] the catalytic chamber is filled with the third catalyst, which is one or more selected from but not limited to the group consisting of commercial nano-ceria, commercial nano-zirconia, commercial nano-alumina, and commercial nano-titania, at a load amount of 0.1 g to 0.6 g, preferably 0.2 gto 0.4 g;

[0055] the gas outlet is connected to the cold trap; the cold trap includes an alkaline drying tube in front of same for absorbing the generated carbon dioxide and residual acetic acid vapor; a filler in the alkaline drying tube is one or more selected from but not limited to the group consisting of potassium hydroxide, sodium hydroxide, and lithium hydroxide powders; and absorbed carbon dioxide is recycled together with the carbon dioxide absorbed in step 1; and

[0056] thc cold trap is configured to recover the acetone liquid.

[0057] In some embodiments, the bipolar membrane-based membrane electrode reactor in step 4 includes a cathode membrane, a bipolar membrane, and an anode membrane that are laminated in sequence, a schematic structure of which is shown in FIG. 5.

[0058] In some embodiments, the electroreduction of the acetone includes subjecting liquid pure acetone to the electroreduction to prepare liquid pure IPA.

[0059] In some embodiments, the cathode membrane is provided with the fourth catalyst, which is one or more selected from but not limited to the group consisting of a commercial nano-ruthenium powder, commercial nano-ruthenium oxide, a lattice-stretched ruthenium catalyst, and a ruthenium- modified carbon material.

[0060] In some embodiments, the bipolar membrane is one or more selected from the group consisting of Fumasep FBM-PK, Aquivion-870-Durion-LMW, Dyneon-725-Durion-LMW, and Nafion-1000-Durion-LMW.

[0061] In some embodiments, a catalytic material of the anode membrane is one or more selected from the group consisting of iridium oxide, ruthenium oxide, nickel foam, metal iridium, metal ruthenium, and a layered iron-nickel bimetallic hydroxide.

[0062] In some embodiments, the bipolar membrane-based membrane electrode reactor further includes a cathode shell having a groove and an anode shell having a groove, and the cathode shell and anode shell are fitted together to form a sealing structure; the cathode shell is provided with a catholyte inlet and a catholyte outlet, and the cathode membrane is arranged in the groove of the cathode shell; the anode shell is provided with an anolyte inlet and an anolyte outlet, and the anode membrane is arranged in the groove of the anode shell.

[0063] In some embodiments, a sealing gasket is arranged between an edge outside the groove of the cathode shell and an edge outside the groove of the anode shell.

[0064] In some embodiments, the catholyte is the acetone, and the acetone is circulated and electrolyzed into the pure IPA in the cathode shell.

[0065] In some embodiments, the anolyte is one or more selected from the group consisting of a lithium hydroxide solution, a sodium hydroxide solution, and a potassium hydroxide solution.

[0066] In some embodiments, step 4 is conducted under the following condition parameters: the acetone is introduced at a flow rate of 30 mL / h to 90 mL / h, the fourth catalyst on an electrode is loaded at 0.5 mg / cm? to 2 mg / cm? the bipolar membrane-based membrane electrode reactor is applied with a voltage of 2.0 V to 6.0 V, and an anolyte has a flow rate of 30 mL / h to 90 mL / h.

[0067] In further embodiments, step 4 is conducted under the following condition parameters: the acetone is introduced at a flow rate of 50 mL / h to 70 mL / h, the fourth catalyst on the electrode is loaded at 0.8 mg / cm? to 1.2 mg / cm?, the bipolar membrane-based membrane electrode reactor is applicd with a voltage of 3.5 V to 4.5 V, and the anolyte has a flow rate of 40 mL / h to 60 mL / h. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] FIG. 1 shows a schematic diagram of a synthetic route for preparing pure IPA from carbon dioxide.

[0069] FIG. 2 shows a schematic structure of the reactor for preparing carbon monoxide by electroreduction of carbon dioxide.

[0070] FIG. 3 shows a schematic structure of the reactor for preparing a pure acetic acid aqueous solution by electroreduction of carbon monoxide.

[0071] FIG. 4 shows a schematic structure of the reactor for preparing acetone by ketonization of acetic acid or an acetate.

[0072] FIG. 5 shows a schematic structure of the reactor for preparing the pure IPA by electroreduction of acetone.

[0073] FIG. 6 shows a Faradaic efficiency of carbon monoxide and hydrogen at different potentials during preparing carbon monoxide by electroreduction of carbon dioxide.

[0074] FIG. 7 shows a bias current of carbon monoxide at different potentials during preparing carbon monoxide by electroreduction of carbon dioxide.

[0075] FIG. 8 shows a Faradaic efficiency of pure acetic acid at different potentials during preparing the pure acetic acid aqueous solution by electroreduction of carbon monoxide.

[0076] FIG. 9 shows a bias current of the pure acetic acid and a mass fraction of the pure acetic acid aqueous solution at different potentials during preparing the pure acetic acid aqueous solution by electroreduction of carbon monoxide.

[0077] FIG. 10 shows hydrogen nuclear magnetic resonance (H-NMR) spectra of commercial IPA and the pure IPA prepared by the method according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0078] In order to further illustrate the present disclosure, the method for preparing pure IPA from carbon dioxide according to present disclosure will be described in detail below in conjunction with the examples. However, it should be understood that these examples are implemented on the premise of the technical solution of the present disclosure, and detailed implementation modes and specific operating processes are given. These examples are only to further illustrate the features and advantages of the present disclosure, but are not intended to limit the claims of the present disclosure. The scope of the present disclosure is not limited to the following examples either.

[0079] Example 1

[0080] Process for preparing carbon monoxide by electroreduction of carbon dioxide:

[0081] I. Synthesis of a nickel single atom-nitrogen-doped activated carbon nano-catalyst:

[0082] (1) 1.95 g of commercial carbon black was dissolved into 100 mL of a 9 mol / L nitric acid solution under stirring at room temperature, and subjected to ultrasonic treatment for 5 min to disperse the carbon black in the nitric acid solution to be uniform. A resulting mixture was placed in a flask and subjected to condensation and reflux at 80°C for 3 h, and then cooled to room temperature. After that, a resulting solid material was centrifuged at 9,000 rpm for 5 min; a product obtained after centrifugation was ultrasonically washed with a polar solvent for 3 min, and then centrifuged again at 9,000 rpm for 3 min. A resulting product was ultrasonically washed with a polar solvent for 2 min, and then vacuum-dried at 65°C overnight to obtain an activated carbon black.

[0083] (2) 1,000 mg of the activated carbon black was dispersed in 400 mL of deionized water solution to obtain a mixed solution A. 40 mL of a nickel nitrate solution with a concentration of 3.0 mg / mL was added to the mixed solution A manually and slowly at a speed of 15 mL / h at room temperature, then stirred vigorously to obtain a mixed solution B. The mixed solution B was stirred at room temperature for 8 h; a resulting stirred material was centrifuged at 8,000 rpm for 5 min; a resulting product was ultrasonically washed with a polar solvent for 1 min, and then centrifuged again at 8,000 rpm for 5 min; and a product obtained after centrifugation was then ultrasonically washed with a polar solvent for 1 min, and then vacuum-dried to obtain an Ni?*-carbon black powder. The Ni**-carbon black powder and urea were uniformly mixed at a mass ratio of 1:10; a resulting mixed sample was placed in a crucible and then placed in a tubular furnace together with the crucible, and subjected to high-temperature sintering in an atmosphere of argon with a flow rate of 100 sccm at 300°C for 1 h, obtaining an Ni single atom-nitrogen-doped activated carbon nano- catalyst.

[0084] After detection, the nickel single atom-nitrogen-doped activated carbon nano-catalyst obtained in this example has a nickel mass percentage of 1.0 wt.%.

[0085] II. Electroreduction of carbon dioxide into carbon monoxide catalyzed by the nickel single atom-nitrogen-doped activated carbon nano-catalyst

[0086] As shown in FIG. 2, a carbon gas diffusion layer loaded with the nickel single atom- nitrogen-doped activated carbon nano-catalyst was used as a cathode, with a loading capacity of 1 mg / cm? In a membrane electrode reactor, an anion exchange membrane layer was closely attached to a surface of the catalyst; iridium oxide supported on a carbon paper was used as an anode and was closely attached to the other side of the anion exchange membrane layer. Silica gel gaskets were added to both sides of the anion exchange membrane layer to ensure sealing, and a titanium plate was added as a current collector. In the membrane electrode reactor, carbon dioxide pure gas was used as a raw material gas for performance testing of the electroreduction of carbon dioxide. The flow rate of carbon dioxide was maintained at 50 sccm and a flow rate of potassium hydroxide electrolyte at the anode was maintained at 60 mL / h during the testing. The testing was conducted by a potentiostatic method. Gas phase products were detected by gas chromatography, while liquid phase products were detected by H-NMR. A coulomb quantity corresponding to the product concentration was calculated, and catalytic selectivity, activity, and other data were obtained based on a total coulomb quantity recorded by an electrochemical workstation. The measured Faradaic efficiency of each product at different potentials is shown in FIG. 6, and the measured carbon monoxide bias current at different potentials is shown in FIG. 7.

[0087] Example 2

[0088] Process for preparing pure acetic acid by electroreduction of carbon monoxide:

[0089] 1. Synthesis of a copper gel nano-catalyst

[0090] 500 mg of hydrated copper chloride and 120 mg of lead nitrate were completely dissolved in 3 mL of IPA at room temperature, and 3 mL of propylene oxide was added to a resulting mixture and subjected to ultrasonic dispersion to be uniform. A resulting mixed solution was added with 0.3 mL of deionized water and dispersed to be uniform and then aged at room temperature for 12 h; and a resulting supernatant was removed after aging, and a resulting solid product was vacuum-dried at 80°C for 12 h to obtain the copper gel nano-catalyst.

[0091] II. Electroreduction of carbon monoxide into pure acetic acid catalyzed by the copper gel nano-catalyst

[0092] As shown in FIG. 3, a carbon gas diffusion layer loaded with the copper gel nano-catalyst was used as a working electrode, with a loading capacity of 1 mg / cm? and a gas flow rate of 50 sccm. In a membrane electrode-based solid electrolyte battery, a carbon gas diffusion layer loaded with the copper-based single-atom alloy catalyst was used as a working electrode, and an anion exchange membrane layer was closely attached to a surface of the catalyst; iridium oxide was used as a counter electrode, a cation exchange membrane layer was closely attached to a surface of the counter electrode, and the solid electrolyte was filled between the anion exchange membrane and the cation exchange membrane to provide electricity. When the carbon monoxide was reduced, acetate anions generated at the cathode moved through the anion exchange membrane toward the solid electrolyte channel in the middle driven by the electric field. At the same time, protons generated by the oxidation of water at the anode could pass through the cation membrane to compensate for the charges. Since the solid electrolyte was a proton conductor, an acetic acid product could be formed through ion recombination at an interface between the solid electrolyte and the anion membrane, and diffused out through liquid deionized water.

[0093] During the actual reaction, deionized water with a flow rate of 50 mL / h was introduced into the solid electrolyte layer to collect acetic acid generated during the electroreduction of carbon monoxide.

[0094] As shown in FIG. 7, FIG. 7 shows the Faradaic efficiency of acetic acid produced at different potentials by the membrane electrode-based solid electrolyte battery containing copper gel nano-catalyst prepared in this example.

[0095] As shown in FIG. 8, FIG. 8 shows the bias current of acetic acid and mass fraction of the acetic acid aqueous solution produced at different potentials by the membrane electrode-based solid electrolyte battery containing copper gel nano-catalyst prepared in this example.

[0096] As shown in FIG. 7 and FIG. 8, the deionized water introduced into the solid electrolyte during the reaction has a flow rate of 50 mL / h. When a total current exceeds 200 mA, a selectivity of the pure acetic acid remains not less than 40%. The acetic acid collected at 250 mA has a concentration in excess of 2,500 ppm.

[0097] Example 3

[0098] Process for preparing acetone by ketonization of acetic acid:

[0099] Referring to FIG. 4, 0.2 g of a commercial ceria catalyst was ground and pressed into tablets, and loaded into a fixed bed reactor, and then subjected to ketonization at 300°C. Ar was used as a carrier gas to pass through a container containing 2,000 ppm of the acetic acid aqueous solution at 20 sccm, thus bringing acetic acid vapor into the reactor while taking out acetone vapor and by-product carbon dioxide from the reactor; a tail of the reactor was connected to an alkaline drying tube to absorb carbon dioxide, water vapor, and incompletely converted acetic acid, and then connected to a cold trap to collect a liquid. Quantification was conducted by H-NMR.

[0100] Example 4

[0101] Process for preparing the pure IPA by electroreduction of acetone:

[0102] I. Preparation of a lattice-stretched ruthenium nano-catalyst

[0103] step 1: 70 mg of ruthenium dioxide and 5 mL of n-hexane were added into a three-necked flask at room temperature, and refluxed at 65°C for 1 h under nitrogen protection to obtain a mixed solution;

[0104] step 2: 4 mL of n-hexane solution of n-butyllithium with a concentration of 2 mol / L was added to the mixed solution obtained in step 1, refluxed at 65°C for 2 h, washed twice with n- hexane and twice with absolute ethanol, and a resulting precipitate was collected to obtain a lithium-intercalated ruthenium precursor; and

[0105] step 3: the lithium-intercalated ruthenium precursor obtained in step 2 was mixed with 50 mL of deionized water at room temperature, subjected to ultrasonic treatment at room temperature for 1 h under nitrogen protection, centrifuged to remove a supernatant, washed with deionized water for 3 times, then dried in a vacuum oven at 30°C for 12 h to obtain the lattice-stretched ruthenium nano-catalyst.

[0106] II. Elcctrorcduction of acctonc into purc IPA catalyzed by the lattice-stretched ruthenium nano-catalyst

[0107] Referring to FIG. 5, electrocatalytic reduction of acetone was conducted, where a loading capacity of the catalyst on the electrode was 1 mg / cm? the acetone was used as a catholyte, while 1 mol / L potassium hydroxide solution was used as an anolyte, and the electrolyte was circulated at a flow rate maintained at 60 mL / h during the testing. The testing was completed by a potentiostatic method, and full cell showed a potential of -4 V. A liquid phase product was detected by H-NMR after micro-sampling. As shown in FIG. 10, a purity of the pure IPA is comparable to that of commercially available IPA (99.7 wt.%); and calculated based on the purity of commercially available IPA and the ratio of peak areas in H-NMR, a purity of the pure IPA is 99 wt.%.

[0108] The method for preparing pure IPA from carbon dioxide according to the present disclosure are described in detail above, and specific examples are used herein to illustrate the principle and embodiments of the present disclosure. The examples (including the optimal mode) are illustrated above merely to help understand the method and concept of the present disclosure and allow any person skilled in the art to practice the present disclosure, including manufacturing and using any device or system and implementing any combined method. It should be noted that, several improvements and modifications may be made by a person of ordinary skill in the art without departing from the principle of the present disclosure, and these improvements and modifications should also fall within the scope of the present disclosure. The scope of the present disclosure is defined by the claims and may encompass other embodiments that those skilled in the art can think of. If these other embodiments have structural elements that are not different from the literal expression in the claims or include equivalent structural elements that are not substantially different from the literal expression in the claims, they should also be included in the scope of the claims.

Claims

WHAT IS CLAIMED IS:

1. A method for preparing pure isopropyl alcohol (IPA) from carbon dioxide, comprising: preparing the pure IPA from raw materials comprising the carbon dioxide and water.

2. The method according to claim 1, comprising 4 steps of: subjecting the carbon dioxide to first electroreduction to obtain carbon monoxide, subjecting the carbon monoxide to second electroreduction to obtain a pure acetic acid (or acetate) aqueous solution, subjecting the pure acetic acid (or acetate) aqueous solution to ketonization to obtain acetone, and subjecting the acetone to third electroreduction to obtain the pure IPA; ‘wherein the following technical requirements are made to comply with this route and ensure an efficiency of this entire route.

3. The method according to claim 2, wherein subjecting the carbon dioxide to first electroreduction to obtain carbon monoxide is performed by using an anion exchange membrane- based membrane electrode reactor equipped with accessories under the action of a first catalyst at ambient temperature and ambient pressure; the carbon monoxide is obtained at a cathode; and during the first electroreduction, the carbon dioxide is introduced at a flow rate of 5 standard cubic centimeters per minute (sccm) to 100 sccm, the first catalyst on an electrode is loaded at 0.5 mg / cm? to 2 mg / cm’, the anion exchange membrane-based membrane electrode reactor is applied with a voltage of 1.8 V to 3.0 V, an anolyte is at a flow rate of 30 mL / h to 600 mL / h, and a purity of the carbon monoxide during the first clectroreduction does not affect subsequent processes.

4. The method according to claim 3, wherein the first catalyst is one or more selected from but not limited to the group consisting of nickel single atom-nitrogen-doped activated carbon, iron single atom-nitrogen-doped activated carbon, a cobalt phthalocyanine (CoPc) molecule, a commercial zinc oxide nanoparticle, a commercial nano-gold powder, and a commercial nano-silver powder.

5. The method according to claim 2, wherein subjecting the carbon monoxide to second electroreduction to obtain the pure acetic acid aqueous solution is performed by using a solid electrolyte-based membrane electrode reactor equipped with accessories under the action of a second catalyst at ambient temperature and ambient pressure; and during the second electroreduction, the carbon monoxide is introduced at a flow rate of 5 sccm to 100 sccm, the second catalyst on an electrode is loaded at 0.5 mg / em? to 2 mg / cm? the solid electrolyte-based membrane electrode reactor is applied with a voltage of 2.0 V to 3.0 V, deionized water that carries the acetic acid has a flow rate of 10 mL / h to 60 mL / h, an anolyte is at a flow rate of 30 mL / h to 600 mL / h, and a purity of the pure acetic acid aqueous solution during the second electroreduction does not affect subsequent processes.

6. The method according to claim 5, wherein the second catalyst is one or more selected from but not limited to the group consisting of a copper gel, a heterogeneous metal atom-doped copper gel, a copper nanocube, a copper nanosheet, a copper nanowire, a copper multilayer spherical shell, a copper particle-modified carbon material, and a commercial nano-copper powder.

7. The method according to claim 2, wherein subjecting the pure acetic acid (or acetate) aqueous solution to ketonization to obtain acetone is performed by using a fixed bed reactor equipped with accessories under the action of a third catalyst at 300°C and ambient pressure; during the ketonization, the third catalyst is loaded at 0.1 g to 0.6 g in the fixed bed reactor, a carrier gas has a flow rate of 5 sccm to 30 sccm, and the pure acetic acid aqueous solution passed through the carrier gas has a mass concentration of 500 ppm to 3,000 ppm; and the ketonization is conducted at 280°C to 350°C.

8. The method according to claim 7, wherein the third catalyst is one or more selected from but not limited to the group consisting of commercial nano-ceria, commercial nano-zirconia, commercial nano-alumina, and commercial nano-titania.

9. The method according to claim 2, wherein subjecting the acetone to third electroreduction to obtain the pure IPA is performed by using a bipolar membrane-based membrane electrode reactor equipped with accessories under the action of a fourth catalyst without introducing other impurities; and during the third electroreduction, the acetone is introduced at a flow rate of 30 mL / h to 90 mL / h, the fourth catalyst on the electrode is loaded at 0.5 mg / cm? to 2 mg / cm? the bipolar membrane- based membrane electrode reactor is applied with a voltage of 2.0 V to 6.0 V, and an anolyte is at a flow rate of 30 mL / h to 90 mL / h.

10. The method according to claim 9, wherein the fourth catalyst is one or more selected from but not limited to the group consisting of a commercial nano-ruthenium powder, commercial nano- ruthenium oxide, a lattice-stretched ruthenium catalyst, and a ruthenium-modified carbon material. WHAT IS CLAIMED IS:

1. A method for preparing pure isopropyl alcohol (IPA) from carbon dioxide, comprising: preparing the pure IPA from raw materials comprising the carbon dioxide and water.

2. The method according to claim 1, comprising 4 steps of: subjecting the carbon dioxide to first electroreduction to obtain carbon monoxide, subjecting the carbon monoxide to second electroreduction to obtain a pure acetic acid (or acetate) aqueous solution, subjecting the pure acetic acid (or acetate) aqueous solution to ketonization to obtain acetone, and subjecting the acetone to third electroreduction to obtain the pure IPA.

3. The method according to claim 2, wherein subjecting the carbon dioxide to first electroreduction to obtain carbon monoxide is performed by using an anion exchange membrane- based membrane electrode reactor equipped with accessories under the action of a first catalyst at ambient temperature and ambient pressure; the carbon monoxide is obtained at a cathode; and during the first electroreduction, the carbon dioxide is introduced at a flow rate of 5 standard cubic centimeters per minute (sccm) to 100 scem, the first catalyst on an electrode is loaded at 0.5 mg / cm? to 2 mg / cm? the anion exchange membrane-based membrane electrode reactor is applied with a voltage of 1.8 V to 3.0 V, an anolyte is at a flow rate of 30 mL / h to 600 mL / h.

4. The method according to claim 3, wherein the first catalyst is one or more selected from but not limited to the group consisting of nickel single atom-nitrogen-doped activated carbon, iron single atom-nitrogen-doped activated carbon, a cobalt phthalocyanine (CoPc) molecule, a commercial zinc oxide nanoparticle, a commercial nano-gold powder, and a commercial nano-silver powder.

5. The method according to claim 2, wherein subjecting the carbon monoxide to second electroreduction to obtain the pure acetic acid aqueous solution is performed by using a solid electrolyte-based membrane electrode reactor equipped with accessories under the action of a second catalyst at ambient temperature and ambient pressure; and during the second electroreduction, the carbon monoxide is introduced at a flow rate of 5 sccm to 100 sccm, the second catalyst on an electrode is loaded at 0.5 mg / cm? to 2 mg / cm? the solid electrolyte-based membrane electrode reactor is applied with a voltage of 2.0 V to 3.0 V, deionized water that carries the acetic acid has a flow rate of 10 mL / h to 60 mL / h, an anolyte is at a flow rate of 30 mL / h to 600 mL / h.

6. The method according to claim 5, wherein the second catalyst is one or more selected from but not limited to the group consisting of a copper gel, a heterogeneous metal atom-doped copper gel, a copper nanocube, a copper nanosheet, a copper nanowire, a copper multilayer spherical shell, a copper particle-modified carbon material, and a commercial nano-copper powder.

7. The method according to claim 2, wherein subjecting the pure acetic acid (or acetate) aqueous solution to ketonization to obtain acetone is performed by using a fixed bed reactor equipped with accessories under the action of a third catalyst at 300°C and ambient pressure; during the ketonization, the third catalyst is loaded at 0.1 g to 0.6 g in the fixed bed reactor, a carrier gas has a flow rate of 5 sccm to 30 sccm, and the pure acetic acid aqueous solution passed through the carrier gas has a mass concentration of 500 ppm to 3,000 ppm; and the ketonization is conducted at 280°C to 350°C.

8. The method according to claim 7, wherein the third catalyst is one or more selected from but not limited to the group consisting of commercial nano-ceria, commercial nano-zirconia, commercial nano-alumina, and commercial nano-titania.

9. The method according to claim 2, wherein subjecting the acetone to third electroreduction to obtain the pure IPA is performed by using a bipolar membrane-based membrane electrode reactor equipped with accessories under the action of a fourth catalyst; and during the third clectroreduction, the acetone is introduced at a flow rate of 30 mL / h to 90 mL / h, the fourth catalyst on the electrode is loaded at 0.5 mg / cm? to 2 mg / cm, the bipolar membrane- based membrane electrode reactor is applied with a voltage of 2.0 V to 6.0 V, and an anolyte is at a flow rate of 30 mL / h to 90 mL / h.

10. The method according to claim 9, wherein the fourth catalyst is one or more selected from but not limited to the group consisting of a commercial nano-ruthenium powder, commercial nano- ruthenium oxide, a lattice-stretched ruthenium catalyst, and a ruthenium-modified carbon material.

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