EP3710420A1 - Process for producing formic acid - Google Patents

Process for producing formic acid

Info

Publication number
EP3710420A1
EP3710420A1 EP18877890.6A EP18877890A EP3710420A1 EP 3710420 A1 EP3710420 A1 EP 3710420A1 EP 18877890 A EP18877890 A EP 18877890A EP 3710420 A1 EP3710420 A1 EP 3710420A1
Authority
EP
European Patent Office
Prior art keywords
substituted
compound
catalyst
process according
diol
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP18877890.6A
Other languages
German (de)
French (fr)
Other versions
EP3710420A4 (en
Inventor
Vitaly ORDOMSKY
Stéphane STREIFF
Willinton Yesid HERNANDEZ ENCISO
Renate Schwiedernoch
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Solvay SA
Centre National de la Recherche Scientifique CNRS
Original Assignee
Solvay SA
Centre National de la Recherche Scientifique CNRS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Solvay SA, Centre National de la Recherche Scientifique CNRS filed Critical Solvay SA
Publication of EP3710420A1 publication Critical patent/EP3710420A1/en
Publication of EP3710420A4 publication Critical patent/EP3710420A4/en
Pending legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/02—Boron or aluminium; Oxides or hydroxides thereof
    • B01J21/04—Alumina
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/18—Carbon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/44—Palladium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/48—Silver or gold
    • B01J23/52—Gold

Definitions

  • the present invention relates to a process for producing formic acid by the reaction of carbon dioxide with hydrogen in the presence of a solvent, a substituted or non-substituted quinone compound and/or a substituted or non-substituted hydroquinone compound, and a metal catalyst.
  • Formic acid is an important and versatile product. It is used, for example, for acidification in the production of animal feeds, as preservative, as disinfectant, as auxiliary in the textile and leather industry, as a mixture with its salts for deicing aircraft and runways and also as synthetic building block in the chemical industry.
  • the present invention relates to a process for producing formic acid, comprising reacting carbon dioxide with hydrogen in the presence of a solvent, a substituted or non-substituted quinone compound and/or a substituted or non-substituted hydroquinone compound, and a catalyst comprising a metal chosen from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, Ir, Ni and Co.
  • the present invention also relates to a composition
  • a composition comprising:
  • a catalyst comprising a metal chosen from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, Ir, Ni and Co.
  • any particular upper concentration can be associated with any particular lower concentration.
  • hydrocarbon group refers to a group which contains carbon and hydrogen bonds.
  • a hydrocarbon group may be linear, branched, or cyclic, and may contain a heteroatom such as oxygen, nitrogen, sulfur, halogen, etc.
  • alkyl means a saturated hydrocarbon radical, which may be straight, branched or cyclic, such as, methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, t-butyl, pentyl, n-hexyl, cyclohexyl.
  • alkenyl as a group or part of a group denotes an aliphatic hydrocarbon group containing at least one carbon-carbon double bond and which may be straight or branched.
  • the group may contain a plurality of double bonds in the normal chain and the orientation about each is independently E or Z.
  • Exemplary alkenyl groups include, but are not limited to, ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl and nonenyl.
  • the group may be a terminal group or a bridging group.
  • aryl refers to a monovalent aromatic hydrocarbon group, including bridged ring and/or fused ring systems, containing at least one aromatic ring. Examples of aryl groups include phenyl, naphthyl and the like.
  • arylalkyl or the term “aralkyl” refers to alkyl substituted with an aryl.
  • arylalkoxy refers to an alkoxy substituted with aryl.
  • cyclic group means a closed ring hydrocarbon group that is classified as an alicyclic group, aromatic group, or heterocyclic group.
  • alicyclic group means a cyclic hydrocarbon group having properties resembling those of aliphatic groups.
  • cycloalkyl as used herein means cycloalkyl groups containing from 3 to 8 carbon atoms, such as for example cyclohexyl.
  • Heterocyclic may also mean a heterocyclic group fused with a benzene-ring wherein the fused rings contain carbon atoms together with 1 or 2 heteroatom’s which are selected from N, O and S.
  • the present invention relates to a process for producing formic acid, comprising reacting carbon dioxide with hydrogen in the presence of a solvent, a substituted or non-substituted quinone compound and/or a substituted or non-substituted hydroquinone compound, and a catalyst comprising a metal chosen from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, Ir, Ni and Co.
  • the reaction can be performed under wild reaction conditions. No high gas pressure and high reaction temperature is needed when the substituted or non-substituted quinone compound and/or the substituted or non-substituted hydroquinone compound is added into the reaction medium.
  • the class includes some heterocyclic compounds.
  • the class includes some heterocyclic compounds.
  • the substituted or non-substituted quinone compound, or the substituted or non-substituted hydroquinone compound may have 5 to 20 carbon atoms.
  • the substituted or non-substituted quinone compound, or the substituted or non-substituted hydroquinone compound may comprise at least one cyclic ring. More preferably, the substituted or non-substituted quinone compound, or the substituted or non-substituted hydroquinone compound comprises one, two or three cyclic rings, which can be bridged ring and/or fused ring systems.
  • the substituted or non-substituted quinone compound, or the substituted or non-substituted hydroquinone compound comprises at least one five-membered or six-membered ring.
  • the substituted or non-substituted quinone compound, or the substituted or non-substituted hydroquinone compound comprises cyclic ring which contains carbon atoms together with 1 or 2 heteroatoms which are selected from N, O and S.
  • non-substituted quinone compound examples include 1, 2-benzoquinone, 1, 4-benzoquinone, 1, 4-naphthoquinone, 9, 10-phenanthraquinone and 9, 10-anthraquinone.
  • non-substituted hydroquinone compound examples include benzene-1, 4-diol, benzene-1, 2-diol, naphthalene-1, 4-diol, phenanthrene-9, 10-diol and anthracene-9, 10-diol.
  • the substituted quinone compound or substituted hydroquinone compound can bear one or more substituents.
  • Said substituent may be hydroxyl, halo, amino, C 1 -C 12 hydrocarbon group, such as alkyl, alkenyl, aryl, cycloalkyl, C 1 -C 12 hydroxyalkyl or C 1 -C 12 haloalkyl.
  • Preferred substituent may be C 1 -C 5 straight aliphatic hydrocarbon group.
  • substituted quinone compound may have a general formula (I) :
  • R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is C 1 -C 12 alkyl.
  • At least one of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is C 1 -C 5 alkyl.
  • the substituted quinone compound is 1-methyl-9, 10-anthraquinone, 2-methyl-9, 10-anthraquinone, 1-ethyl-9, 10-anthraquinone, 2-ethyl-9, 10-anthraquinone, 1-amyl-9, 10-anthraquinone or 2-amyl-9, 10-anthraquinone. More preferably, the substituted quinone compound is 2-ethyl-9, 10-anthraquinone.
  • substituted hydroquinone compound may have a general formula (II):
  • R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is C 1 -C 12 alkyl.
  • At least one of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is C 1 -C 5 alkyl.
  • the substituted hydroquinone compound is 1-methylanthracene-9, 10-diol, 2-methylanthracene-9, 10-diol, 1-ethylanthracene-9, 10-diol, 2-ethylanthracene-9, 10-diol, 1-amylanthracene-9, 10-diol or 2-amylanthracene-9, 10-diol. More preferably, the substituted hydroquinone compound is 2-ethylanthracene-9, 10-diol.
  • a mixture of the substituted or non-substituted quinone compound and the substituted or non-substituted hydroquinone compound can be added into the reaction medium.
  • the substituted or non-substituted quinone compound and the substituted or non-substituted hydroquinone compound can be mixed before being introduced to the reaction medium. Alternatively, only the substituted or non- substituted quinone compound is added into the reaction medium and then the mixture forms when partial substituted or non-substituted quinone compound is hydrogenated to the substituted or non-substituted hydroquinone compound during the reaction of carbon dioxide with hydrogen.
  • the catalyst comprises a metal chosen from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, Ir, Co and Ni.
  • the catalyst can be a supported or non-supported metal catalyst.
  • the catalyst is a supported metal catalyst.
  • the support is not particularly limited. Typical examples of support are carbon, alumina, titania and silica.
  • the loading of metal on the support may be from 1 wt. %to 50 wt. %.
  • the supported metal catalyst can comprise only one metal element.
  • the supported metal catalyst can comprise at least two metal elements.
  • the catalyst comprises two metal elements.
  • the supported metal catalyst may comprise at least one noble metal element chosen from the group consisting of Pd, Pt, Ru and Au. More preferably, the supported metal catalyst comprises Pd.
  • Preferred supported metal catalyst may be Pd/Al 2 O 3 , Pd/C and Pd-Au/C.
  • the catalyst of present invention can even be Raney-type catalysts such as Raney nickel, Raney cobalt.
  • the catalyst is Raney nickel.
  • Raney nickel is an alloy containing catalytically active nickel and a catalytically inactive component, such as aluminum or silicon.
  • the Raney nickel alloy always has a very high surface area and also contains hydrogen gas (H 2 ) adsorbed on the nickel surface.
  • the Raney nickel mentioned above may notably be Ni-Al, Ni-Si, Ni-Sn, Ni-Co-Si alloys. Among these, Ni-Al alloy is more preferable.
  • the weight ratio of the substituted or non-substituted quinone compound and/or the substituted or non-substituted hydroquinone compound to the catalyst according to the invention may be in the range of 0.01 to 100 and preferably 0.01 to 10.
  • the weight ratio of the substituted or non-substituted quinone compound and/or the substituted or non-substituted hydroquinone compound to the supported metal catalyst is in the range of 0.1 to 2 and preferably 0.5 to 1.5.
  • the reaction according to the invention may be performed in the absence or in the presence of a solvent.
  • the solvent may be protic, aprotic or a combination of protic and aprotic solvents.
  • suitable solvent include water, toluene, octanol, xylene, benzene, n-butanol, and acetonitrile.
  • the reaction medium can be a two-liquid-phase system, such as a mixture of water and an organic solvent that is immiscible with water.
  • the reaction medium can be a single-liquid-phase system.
  • the reaction medium can optionally comprise a basic compound.
  • the basic compound is an amine.
  • the basic compound can notably be lithium hydroxide (LiOH) , sodium hydroxide (NaOH) , potassium hydroxide (KOH) , rubidium hydroxide (RbOH) , caesium hydroxide (CsOH) , sodium carbonate (Na 2 CO 3 ) , sodium bicarbonate (NaHCO 3 ) , potassium carbonate (K 2 CO 3 ) , potassium bicarbonate (KHCO 3 ) , trimethylamine (N (CH 3 ) 3 ) or triethylamine (N (CH 2 CH 3 ) 3 ) .
  • Preferred basic compounds are trimethylamine (N (CH 3 ) 3 ) , triethylamine (N (CH 2 CH 3 ) 3 ) , sodium hydroxide (NaOH) and potassium hydroxide (KOH) .
  • the basic compound can help to increase the yield of formic acid.
  • the basic compound can easily be separated from formic acid by well-known ways. For instance, when trimethylamine (N (CH 3 ) 3 ) or triethylamine (N (CH 2 CH 3 ) 3 ) is added to the reaction medium, it can be removed by evaporation.
  • Carbon dioxide (CO 2 ) according to the present invention is in the gas form.
  • the gas pressure of CO 2 may be from 2 bar to 40 bar and preferably from 25 bar to 35 bar.
  • the gas pressure of H 2 may be from 2 bar to 40 bar and preferably from 25 bar to 35 bar.
  • the reaction temperature according to the present invention may be from 25°C to 80°C.
  • the reaction time according to the present invention may be from 1 hour to 20 hours and preferably from 2 hour to 6 hours.
  • the process according to the present invention may be a one-step process.
  • the catalyst comprising a metal chosen from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, Ir, Ni and Co, and optionally the basic compound together, formic acid is then produced under reaction condition as mentioned above.
  • the metal catalyst is first modified by the deposition of the substituted or non-substituted quinone compound and/or the substituted or non-substituted hydroquinone compound. Afterwards, by mixing carbon dioxide, hydrogen, the solvent, modified metal catalyst and optionally the basic compound together, formic acid is then produced under reaction condition above mentioned.
  • the process involves the following steps:
  • step (iii) reacting carbon dioxide with hydrogen in the presence of a solvent, the solid composite obtained at step (ii) , and optionally a basic compound.
  • the catalyst in step (i) can be preferably supported metal catalyst comprising at least one noble metal element chosen from the group consisting of Pd, Pt, Ru and Au.
  • the solvent in step (i) or step (iii) is not particularly limited.
  • the solvent in step (i) can preferably be some organic solvents, such as toluene, octanol, xylene, benzene, n-butanol, and acetonitrile.
  • the solvent in step (iii) can preferably be water.
  • the concentration of formic acid produced by above mentioned multi-step process may be in the range of 0.60 to 0.80 mol/L.
  • the reaction results in the obtention of a solid comprising the catalyst and a reaction product.
  • the process then comprises the additional steps of:
  • step (iv) exposing the solution obtained at step (iii) to a basic compound and then heating the solution.
  • the catalyst in this embodiment can be preferably a supported metal catalyst comprising at least one noble metal element chosen from the group consisting of Pd, Pt, Ru and Au.
  • the weight ratio of the substituted or non-substituted quinone compound and/or the substituted or non-substituted hydroquinone compound to the supported metal catalyst in this embodiment is in the range of 10 to 80 and preferably 15 to 50.
  • the non-polar solvent can be toluene, xylene or benzene.
  • the polar solvent in step (ii) can be methanol, ethanol or water.
  • step (iv) as the same meaning as above mentioned.
  • the heating in step (iv) is performed under an inert or CO 2 atmosphere.
  • the heating temperature is from 25°C to 80°C.
  • the concentration of formic acid produced by above mentioned multi-step process may be in the range of 0.60 to 1.00 mol/L.
  • the present invention also relates to a composition
  • a composition comprising:
  • a catalyst comprising a metal chosen from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, Ir, Ni and Co.
  • the composition may further comprise a basic compound.
  • the catalyst was prepared by addition of 50 mg of 14 wt. %Pd-26 wt. %Au/C in the solution of 50 mg 2-ethyl-9, 10-anthraquinone (EQ) dissolved in 1 ml of xylene. Solvent was removed afterwards in the rotovap and the catalyst was dried at 80°C in vacuum.
  • the catalyst was added in 50 ml stainless steel reactor together with 0.6 g of trimethylamine in 4 g of water as formic acid extracting solution.
  • the reactor was sealed and pressurized with 30 bar of H 2 and 30 bar of CO 2 .
  • the reaction was heated to 60°C for 17 h under continuous stirring. After reaction the products were analyzed by NMR and Ionic conductivity method.
  • the amount of produced formic acid was 115 mg with concentration 0.65 M in aqueous solution. No other products of CO 2 hydrogenation was observed in the products.
  • the catalyst was prepared by addition of 50 mg of 40 wt. %Pd/C in the solution of 50 mg 2-ethyl-9, 10-anthraquinone (EQ) dissolved in 1 ml of xylene. Solvent was removed afterwards in the rotovap and the catalyst was dried at 80°C in vacuum.
  • the catalyst was added in 50 ml stainless steel reactor together with 0.9 g of trimethylamine in 6 g of water as formic acid extracting solution.
  • the reactor was sealed and pressurized with 30 bar of H 2 and 30 bar of CO 2 .
  • the reaction was heated to 60°C for 5 h under continuous stirring. After reaction the products were analyzed by NMR and Ionic conductivity method.
  • the amount of produced formic acid was 154 mg with concentration 0.55 M in aqueous solution. No other products of CO 2 hydrogenation was observed in the products.
  • the catalyst was prepared by addition of 50 mg of 40 wt. %Pd/C in the solution of 100 mg 2-ethyl-9, 10-anthraquinone (EQ) dissolved in 1 ml of xylene. Solvent was removed afterwards in the rotovap and the catalyst was dried at 80°C in vacuum.
  • EQ 2-ethyl-9, 10-anthraquinone
  • the catalyst was added in 50 ml stainless steel reactor together with 0.9 g of trimethylamine in 6 g of water as formic acid extracting solution.
  • the reactor was sealed and pressurized with 30 bar of H 2 and 30 bar of CO 2 .
  • the reaction was heated to 60°C for 5 h under continuous stirring. After reaction the products were analyzed by NMR and Ionic conductivity method.
  • the amount of produced formic acid was 2234 mg with concentration 0.81 M in aqueous solution. No other products of CO 2 hydrogenation was observed in the products.
  • the test like in the example 13 has been repeated 3 times by recycling and reusing the metal catalyst.
  • the amount of produced formic acid was 157, 149 and 152 mg. It indicates on high reproducibility of the results and high efficiency of the process.

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  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
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Abstract

Provided is a process for producing formic acid by the reaction of carbon dioxide with hydrogen in the presence of a heterogeneous catalyst.

Description

    Process for Producing Formic Acid
  • CROSS-REFERENCE TO RELATED APPLICATION
  • The present application claims priority to International Application No. PCT/CN2017/110998 filed on 15 Nov 2017, the whole content of this application being incorporated herein by reference.
  • Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.
    • TECHNICAL FIELD
  • The present invention relates to a process for producing formic acid by the reaction of carbon dioxide with hydrogen in the presence of a solvent, a substituted or non-substituted quinone compound and/or a substituted or non-substituted hydroquinone compound, and a metal catalyst.
  • BACKROUND
  • The conversion of carbon dioxide into useful products becomes more attractive for energy storage and chemical production as CO 2 levels in the atmosphere continue to rise as a consequence of human activities.
  • Formic acid is an important and versatile product. It is used, for example, for acidification in the production of animal feeds, as preservative, as disinfectant, as auxiliary in the textile and leather industry, as a mixture with its salts for deicing aircraft and runways and also as synthetic building block in the chemical industry.
  • The hydrogenation of CO 2 to produce formic acid in the presence of a metal-containing catalyst is well known.
  • For example, Leitner et al., Angewandte Chemie., 55, (2016) , 8966-8969 reports a hydrogenation of CO 2 to formic acid with a highly active ruthenium acriphos complex in DMSO and DMSO/water. Laurenczy et al. Nature Commun., 5, (2014) , art. no. 4017 teaches the use of ruthenium catalyst in the direct synthesis of formic acid from CO 2 in acidic media. However, the metal-containing catalysts are all homogenous, which make it difficult to remove  the catalyst from the product. Furthermore, such reactions usually require relatively high pressure, long reaction time or specific organic solvents, such as DMSO.
  • The use of some heterogeneous metal-containing catalysts has also been reported in the processes for producing formic acid by the reaction of carbon dioxide with hydrogen. Yamashita et al. ACS catal., 7, (2017) , 3147-3151 discloses single-site Ru catalyst on the surface of a layered double hydroxide in a basic medium is proven to be efficient for selective hydrogenation of CO 2 to formic acid. Yoon et al. Inorg. Chem. Front., 3, (2016) , 882-895 reports catalytic hydrogenation of CO 2 to formic acid by using some supported noble metals, such as Pd/Al 2O 3 and Au/Al 2O 3. However, the reactions also need high pressure, high temperature or long reaction time when CO 2 is directly used as reactant.
  • It is an objective of the present invention to improve the process for producing formic acid by reaction of carbon dioxide with hydrogen in the presence of a metal catalyst.
  • SUMMARY OF INVENTION
  • In one aspect, the present invention relates to a process for producing formic acid, comprising reacting carbon dioxide with hydrogen in the presence of a solvent, a substituted or non-substituted quinone compound and/or a substituted or non-substituted hydroquinone compound, and a catalyst comprising a metal chosen from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, Ir, Ni and Co.
  • The present invention also relates to a composition comprising:
  • (i) carbon dioxide,
  • (ii) hydrogen,
  • (iii) a solvent,
  • (iv) a substituted or non-substituted quinone compound and/or a substituted or non-substituted hydroquinone compound, and
  • (v) a catalyst comprising a metal chosen from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, Ir, Ni and Co.
  • DEFINITIONS
  • For convenience, before further description of the present disclosure, certain terms employed in the specification, and examples are collected here.  These definitions should be read in the light of the remainder of the disclosure and understood as by a person of skill in the art. The terms used herein have the meanings recognized and known to those of skill in the art, however, for convenience and completeness, particular terms and their meanings are set forth below.
  • The articles “a” , “an” and “the” are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article.
  • The term “and/or” includes the meanings “and” , “or” and also all the other possible combinations of the elements connected to this term.
  • Throughout the description, including the claims, the term "comprising one" should be understood as being synonymous with the term "comprising at least one" , unless otherwise specified, and "between" should be understood as being inclusive of the limits.
  • It should be noted that in specifying any range of concentration, any particular upper concentration can be associated with any particular lower concentration.
  • It is specified that, in the continuation of the description, unless otherwise indicated, the values at the limits are included in the ranges of values which are given.
  • As used herein, the term "hydrocarbon group" refers to a group which contains carbon and hydrogen bonds. A hydrocarbon group may be linear, branched, or cyclic, and may contain a heteroatom such as oxygen, nitrogen, sulfur, halogen, etc.
  • As used herein, the term "alkyl" means a saturated hydrocarbon radical, which may be straight, branched or cyclic, such as, methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, t-butyl, pentyl, n-hexyl, cyclohexyl.
  • As used herein, the term "alkenyl" as a group or part of a group denotes an aliphatic hydrocarbon group containing at least one carbon-carbon double bond and which may be straight or branched. The group may contain a plurality of double bonds in the normal chain and the orientation about each is independently E or Z. Exemplary alkenyl groups include, but are not limited to, ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl and nonenyl. The group may be a terminal group or a bridging group.
  • As used herein, the term "aryl" refers to a monovalent aromatic hydrocarbon group, including bridged ring and/or fused ring systems, containing at least one aromatic ring. Examples of aryl groups include phenyl, naphthyl and  the like. The term "arylalkyl" or the term "aralkyl" refers to alkyl substituted with an aryl. The term "arylalkoxy" refers to an alkoxy substituted with aryl.
  • As used herein, the term "cyclic group" means a closed ring hydrocarbon group that is classified as an alicyclic group, aromatic group, or heterocyclic group. The term "alicyclic group" means a cyclic hydrocarbon group having properties resembling those of aliphatic groups.
  • As used herein, the term "cycloalkyl" as used herein means cycloalkyl groups containing from 3 to 8 carbon atoms, such as for example cyclohexyl.
  • "Heterocyclic" may also mean a heterocyclic group fused with a benzene-ring wherein the fused rings contain carbon atoms together with 1 or 2 heteroatom’s which are selected from N, O and S.
  • As used herein, the terminology " (C n-C m) " in reference to an organic group, wherein n and m are each integers, indicates that the group may contain from n carbon atoms to m carbon atoms per group.
    • DETAILED DESCRIPTION
  • In one aspect, the present invention relates to a process for producing formic acid, comprising reacting carbon dioxide with hydrogen in the presence of a solvent, a substituted or non-substituted quinone compound and/or a substituted or non-substituted hydroquinone compound, and a catalyst comprising a metal chosen from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, Ir, Ni and Co.
  • Without wishing to be bound by any theory, the reaction can be performed under wild reaction conditions. No high gas pressure and high reaction temperature is needed when the substituted or non-substituted quinone compound and/or the substituted or non-substituted hydroquinone compound is added into the reaction medium.
  • As used herein, the quinone compounds represent a class of organic compounds that are formally derived from aromatic compounds, such as benzene or naphthalene by conversion of an even number of –CH= groups into –C (=O) –groups with any necessary rearrangement of double bonds, resulting in a fully conjugated cyclic dione structure. The class includes some heterocyclic compounds.
  • As used herein, the hydroquinone compounds represent a class of organic compounds that are formally derived from the quinone compounds, by  conversion of –C (=O) –groups into –C (–OH) –groups. The class includes some heterocyclic compounds.
  • Preferably, the substituted or non-substituted quinone compound, or the substituted or non-substituted hydroquinone compound may have 5 to 20 carbon atoms.
  • Preferably, the substituted or non-substituted quinone compound, or the substituted or non-substituted hydroquinone compound may comprise at least one cyclic ring. More preferably, the substituted or non-substituted quinone compound, or the substituted or non-substituted hydroquinone compound comprises one, two or three cyclic rings, which can be bridged ring and/or fused ring systems.
  • Advantageously, the substituted or non-substituted quinone compound, or the substituted or non-substituted hydroquinone compound comprises at least one five-membered or six-membered ring.
  • In some embodiments, the substituted or non-substituted quinone compound, or the substituted or non-substituted hydroquinone compound comprises cyclic ring which contains carbon atoms together with 1 or 2 heteroatoms which are selected from N, O and S.
  • Examples of the non-substituted quinone compound are 1, 2-benzoquinone, 1, 4-benzoquinone, 1, 4-naphthoquinone, 9, 10-phenanthraquinone and 9, 10-anthraquinone.
  • Examples of the non-substituted hydroquinone compound are benzene-1, 4-diol, benzene-1, 2-diol, naphthalene-1, 4-diol, phenanthrene-9, 10-diol and anthracene-9, 10-diol.
  • The substituted quinone compound or substituted hydroquinone compound can bear one or more substituents. Said substituent may be hydroxyl, halo, amino, C 1-C 12 hydrocarbon group, such as alkyl, alkenyl, aryl, cycloalkyl, C 1-C 12hydroxyalkyl or C 1-C 12 haloalkyl.
  • Preferred substituent may be C 1-C 5 straight aliphatic hydrocarbon group.
  • Notably, the substituted quinone compound may have a general formula (I) :
  • wherein at least one of R 1, R 2, R 3, R 4, R 5, R 6, R 7 and R 8 is C 1-C 12 alkyl.
  • Preferably, at least one of R 1, R 2, R 3, R 4, R 5, R 6, R 7 and R 8 is C 1-C 5 alkyl.
  • In one preferred embodiment of the present invention, the substituted quinone compound is 1-methyl-9, 10-anthraquinone, 2-methyl-9, 10-anthraquinone, 1-ethyl-9, 10-anthraquinone, 2-ethyl-9, 10-anthraquinone, 1-amyl-9, 10-anthraquinone or 2-amyl-9, 10-anthraquinone. More preferably, the substituted quinone compound is 2-ethyl-9, 10-anthraquinone.
  • Notably, the substituted hydroquinone compound may have a general formula (II):
  • wherein at least one of R 1, R 2, R 3, R 4, R 5, R 6, R 7 and R 8 is C 1-C 12 alkyl.
  • Preferably, at least one of R 1, R 2, R 3, R 4, R 5, R 6, R 7 and R 8 is C 1-C 5 alkyl.
  • In one preferred embodiment of the present invention, the substituted hydroquinone compound is 1-methylanthracene-9, 10-diol, 2-methylanthracene-9, 10-diol, 1-ethylanthracene-9, 10-diol, 2-ethylanthracene-9, 10-diol, 1-amylanthracene-9, 10-diol or 2-amylanthracene-9, 10-diol. More preferably, the substituted hydroquinone compound is 2-ethylanthracene-9, 10-diol.
  • According to the present invention, a mixture of the substituted or non-substituted quinone compound and the substituted or non-substituted hydroquinone compound can be added into the reaction medium.
  • The substituted or non-substituted quinone compound and the substituted or non-substituted hydroquinone compound can be mixed before being introduced to the reaction medium. Alternatively, only the substituted or non- substituted quinone compound is added into the reaction medium and then the mixture forms when partial substituted or non-substituted quinone compound is hydrogenated to the substituted or non-substituted hydroquinone compound during the reaction of carbon dioxide with hydrogen.
  • It has been discovered that high concentration of formic acid can be obtained at the end of reaction when the substituted or non-substituted quinone compound and/or the substituted or non-substituted hydroquinone compound is introduced into the reaction medium.
  • According to the present invention, the catalyst comprises a metal chosen from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, Ir, Co and Ni.
  • The catalyst can be a supported or non-supported metal catalyst.
  • Advantageously, the catalyst is a supported metal catalyst. The support is not particularly limited. Typical examples of support are carbon, alumina, titania and silica. The loading of metal on the support may be from 1 wt. %to 50 wt. %.
  • In some embodiments, the supported metal catalyst can comprise only one metal element.
  • In some embodiments, the supported metal catalyst can comprise at least two metal elements. Preferably, the catalyst comprises two metal elements.
  • Preferably, the supported metal catalyst may comprise at least one noble metal element chosen from the group consisting of Pd, Pt, Ru and Au. More preferably, the supported metal catalyst comprises Pd.
  • Preferred supported metal catalyst may be Pd/Al 2O 3, Pd/C and Pd-Au/C.
  • The catalyst of present invention can even be Raney-type catalysts such as Raney nickel, Raney cobalt. Preferably, the catalyst is Raney nickel.
  • Raney nickel is an alloy containing catalytically active nickel and a catalytically inactive component, such as aluminum or silicon. The Raney nickel alloy always has a very high surface area and also contains hydrogen gas (H 2) adsorbed on the nickel surface.
  • The Raney nickel mentioned above may notably be Ni-Al, Ni-Si, Ni-Sn, Ni-Co-Si alloys. Among these, Ni-Al alloy is more preferable.
  • The weight ratio of the substituted or non-substituted quinone compound and/or the substituted or non-substituted hydroquinone compound to the catalyst according to the invention may be in the range of 0.01 to 100 and preferably 0.01 to 10.
  • In one preferred embodiment, the weight ratio of the substituted or non-substituted quinone compound and/or the substituted or non-substituted  hydroquinone compound to the supported metal catalyst is in the range of 0.1 to 2 and preferably 0.5 to 1.5.
  • The reaction according to the invention may be performed in the absence or in the presence of a solvent. The solvent may be protic, aprotic or a combination of protic and aprotic solvents. Examples of suitable solvent include water, toluene, octanol, xylene, benzene, n-butanol, and acetonitrile.
  • In some embodiments, the reaction medium can be a two-liquid-phase system, such as a mixture of water and an organic solvent that is immiscible with water.
  • In some embodiments, the reaction medium can be a single-liquid-phase system.
  • The reaction medium can optionally comprise a basic compound. Preferably, the basic compound is an amine. The basic compound can notably be lithium hydroxide (LiOH) , sodium hydroxide (NaOH) , potassium hydroxide (KOH) , rubidium hydroxide (RbOH) , caesium hydroxide (CsOH) , sodium carbonate (Na 2CO 3) , sodium bicarbonate (NaHCO 3) , potassium carbonate (K 2CO 3) , potassium bicarbonate (KHCO 3) , trimethylamine (N (CH 3)  3) or triethylamine (N (CH 2CH 3)  3) . Preferred basic compounds are trimethylamine (N (CH 3)  3) , triethylamine (N (CH 2CH 3)  3) , sodium hydroxide (NaOH) and potassium hydroxide (KOH) .
  • It should be understood by the skilled people that the basic compound can help to increase the yield of formic acid. The basic compound can easily be separated from formic acid by well-known ways. For instance, when trimethylamine (N (CH 3)  3) or triethylamine (N (CH 2CH 3)  3) is added to the reaction medium, it can be removed by evaporation.
  • Carbon dioxide (CO 2) according to the present invention is in the gas form. The gas pressure of CO 2 may be from 2 bar to 40 bar and preferably from 25 bar to 35 bar.
  • The gas pressure of H 2 may be from 2 bar to 40 bar and preferably from 25 bar to 35 bar.
  • The reaction temperature according to the present invention may be from 25℃ to 80℃.
  • The reaction time according to the present invention may be from 1 hour to 20 hours and preferably from 2 hour to 6 hours.
  • The process according to the present invention may be a one-step process. By mixing carbon dioxide, hydrogen, the solvent, the substituted or non- substituted quinone compound and/or the substituted or non-substituted hydroquinone compound, the catalyst comprising a metal chosen from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, Ir, Ni and Co, and optionally the basic compound together, formic acid is then produced under reaction condition as mentioned above.
  • In some embodiments, the metal catalyst is first modified by the deposition of the substituted or non-substituted quinone compound and/or the substituted or non-substituted hydroquinone compound. Afterwards, by mixing carbon dioxide, hydrogen, the solvent, modified metal catalyst and optionally the basic compound together, formic acid is then produced under reaction condition above mentioned. In this case, the process involves the following steps:
  • (i) mixing a substituted or non-substituted quinone compound and/or a substituted or non-substituted hydroquinone compound with a catalyst comprising a metal chosen from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, Ir, Ni and Co in the presence of a solvent,
  • (ii) removing the solvent from the mixture obtained at step (i) , so as to obtain a solid composite, and
  • (iii) reacting carbon dioxide with hydrogen in the presence of a solvent, the solid composite obtained at step (ii) , and optionally a basic compound.
  • The catalyst in step (i) can be preferably supported metal catalyst comprising at least one noble metal element chosen from the group consisting of Pd, Pt, Ru and Au.
  • The solvent in step (i) or step (iii) is not particularly limited. The solvent in step (i) can preferably be some organic solvents, such as toluene, octanol, xylene, benzene, n-butanol, and acetonitrile. The solvent in step (iii) can preferably be water.
  • Advantageously, the concentration of formic acid produced by above mentioned multi-step process may be in the range of 0.60 to 0.80 mol/L.
  • In one specific embodiment, after reacting carbon dioxide with hydrogen in the presence of a non-polar solvent, a substituted or non-substituted quinone compound and/or a substituted or non-substituted hydroquinone compound, and a catalyst comprising a metal chosen from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, Ir, Ni and Co, the reaction results in the obtention of a solid comprising the catalyst and a reaction product. The process then comprises the additional steps of:
  • (i) separating the solid obtained from the reaction medium,
  • (ii) adding a polar solvent to the separated solid to dissolve the reaction product,
  • (iii) separating the catalyst from the solution so obtained, and
  • (iv) exposing the solution obtained at step (iii) to a basic compound and then heating the solution.
  • The catalyst in this embodiment can be preferably a supported metal catalyst comprising at least one noble metal element chosen from the group consisting of Pd, Pt, Ru and Au.
  • The weight ratio of the substituted or non-substituted quinone compound and/or the substituted or non-substituted hydroquinone compound to the supported metal catalyst in this embodiment is in the range of 10 to 80 and preferably 15 to 50.
  • The non-polar solvent can be toluene, xylene or benzene.
  • The polar solvent in step (ii) can be methanol, ethanol or water.
  • The basic compound in step (iv) as the same meaning as above mentioned.
  • Preferably, the heating in step (iv) is performed under an inert or CO 2 atmosphere. The heating temperature is from 25℃ to 80℃.
  • Advantageously, the concentration of formic acid produced by above mentioned multi-step process may be in the range of 0.60 to 1.00 mol/L.
  • The present invention also relates to a composition comprising:
  • (i) carbon dioxide,
  • (ii) hydrogen,
  • (iii) a solvent,
  • (iv) a substituted or non-substituted quinone compound and/or a substituted or non-substituted hydroquinone compound, and
  • (v) a catalyst comprising a metal chosen from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, Ir, Ni and Co.
  • Preferably, the composition may further comprise a basic compound.
  • The following examples are included to illustrate embodiments of the invention. Needless to say, the invention is not limited to the described examples.
  • EXPERIMENTAL PART
  • Raw materials:
  • xylene–Sigma-Aldrich
  • 1-octanol-Sinopharm
  • triethylamine-Sinopharm
  • 2-ethyl-9, 10-anthraquinone-J&K
  • 1, 4-benzoquinone–Sigma-Aldrich
  • benzene-1, 4-diol-Fluka
  • 5 wt. %Pd/Al 2O 3-Johnson Matthey
  • 14 wt. %Pd-26 wt. %Au/C-Premetek
  • EXAMPLE 1: Process in the presence of 2-ethyl-9, 10-anthraquinone (EQ) over Pd catalyst
  • Put in 50 ml stainless steel reactor 1 g of xylene and 1 g of octanol as organic phase with dissolved 50 mg of 2-ethyl-9, 10-anthraquinone (EQ) , 0.3 g of triethylamine in 2 g of water and 50 mg of 5 wt. %Pd/Al 2O 3 as a catalyst for hydrogenation. The reactor was sealed and pressurized with 30 bar of H 2 and 30 bar of CO 2. The reaction was heated to 60℃ for 17 h under continuous stirring. After reaction the products were analyzed by NMR and Ionic conductivity method. The amount of produced formic acid was 34 mg with concentration 0.37 M in aqueous solution. No other products of CO 2 hydrogenation was observed in the products.
  • COMPARATIVE EXAMPLE 1: Process in the absence of 2-ethyl-9, 10-anthraquinone (EQ)
  • Put in 50 ml stainless steel reactor 1 g of xylene and 1 g of octanol as organic phase, 0.3 g of trimethylamine in 2 g of water as formic acid extracting solution and 50 mg of 5 wt. %Pd/Al 2O 3 as a catalyst for hydrogenation. The reactor was sealed and pressurized with 30 bar of H 2 and 30 bar of CO 2. The reaction was heated to 60℃ for 17 h under continuous stirring. After reaction the products were analyzed by NMR and Ionic conductivity method. No formic acid was detected in the products of the reaction.
  • EXAMPLE 2: Process in the presence of 2-ethyl-9, 10-anthraquinone (EQ) over Ni catalyst
  • Put in 50 ml stainless steel reactor 1 g of xylene and 1 g of octanol as organic phase with dissolved 50 mg of 2-ethyl-9, 10-anthraquinone (EQ) , 0.3 g of triethylamine in 2 g of water as formic acid extracting solution and 50 mg of Raney Ni as a catalyst for hydrogenation. The reactor was sealed and pressurized with 30 bar of H 2 and 30 bar of CO 2. The reaction was heated to 60℃ for 17 h under continuous stirring. After reaction the products were analyzed by NMR and Ionic conductivity method. The amount of produced formic acid was 15 mg with concentration 0.16 M in aqueous solution. No other products of CO 2 hydrogenation was observed in the products.
  • EXAMPLE 3: Process in the presence of 2-ethyl-9, 10-anthraquinone (EQ) over Pd-Au catalyst
  • Put in 50 ml stainless steel reactor 1 g of xylene and 1 g of octanol as organic phase with dissolved 50 mg of 2-ethyl-9, 10-anthraquinone (EQ) , 0.3 g of triethylamine in 2 g of water as formic acid extracting solution and 50 mg of 14 wt. %Pd-26wt. %Au/C as a catalyst for hydrogenation. The reactor was sealed and pressurized with 30 bar of H 2 and 30 bar of CO 2. The reaction was heated to 60℃ for 17 h under continuous stirring. After reaction the products were analyzed by NMR and Ionic conductivity method. The amount of produced formic acid was 63 mg with concentration 0.68 M in aqueous solution. No other products of CO 2 hydrogenation was observed in the products.
  • EXAMPLE 4: Process in the absence of triethylamine (TEA) over Pd catalyst
  • Put in 50 ml stainless steel reactor 1 g of xylene and 1 g of octanol as organic phase with dissolved 50 mg of 2-ethyl-9, 10-anthraquinone (EQ) , 2 g of water and 50 mg of 5 wt. %Pd/Al 2O 3 as a catalyst for hydrogenation. The reactor was sealed and pressurized with 30 bar of H 2 and 30 bar of CO 2. The reaction was heated to 60℃ for 17 h under continuous stirring. After reaction the products were analyzed by NMR and Ionic conductivity method. The amount of produced formic acid was 4 mg with concentration 0.04 M in aqueous solution. No other products of CO 2 hydrogenation was observed in the products.
  • EXAMPLE 5: Process in the presence of 1, 4-benzoquinone over Pd catalyst
  • Put in 50 ml stainless steel reactor 1 g of xylene and 1 g of octanol as organic phase with dissolved 50 mg of 1, 4-benzoquinone, 0.3 g of triethylamine in 2 g of water as formic acid extracting solution and 50 mg of 5 wt. %Pd/Al 2O 3 as a catalyst for hydrogenation. The reactor was sealed and pressurized with 30 bar of H 2 and 30 bar of CO 2. The reaction was heated to 60℃ for 5 h under continuous stirring. After reaction the products were analyzed by NMR and Ionic conductivity method. The amount of produced formic acid was 22 mg with concentration 0.25 M in aqueous solution. No other products of CO 2 hydrogenation was observed in the products.
  • EXAMPLE 6: Process in the presence of benzene-1, 4-diol over Pd catalyst
  • Put in 50 ml stainless steel reactor 1 g of xylene and 1 g of octanol as organic phase with dissolved 50 mg of benzene-1, 4-diol, 0.3 g of triethylamine  in 2 g of water as formic acid extracting solution and 50 mg of 5 wt. %Pd/Al 2O 3 as a catalyst for hydrogenation. The reactor was sealed and pressurized with 30 bar of H 2 and 30 bar of CO 2. The reaction was heated to 60℃ for 5 h under continuous stirring. After reaction the products were analyzed by NMR and Ionic conductivity method. The amount of produced formic acid was 21 mg with concentration 0.25 M in aqueous solution. No other products of CO 2 hydrogenation was observed in the products.
  • EXAMPLE 7: Process at low temperature over Pd catalyst
  • Put in 50 ml stainless steel reactor 1 g of xylene and 1 g of octanol as organic phase with dissolved 50 mg of 2-ethyl-9, 10-anthraquinone (EQ) , 0.3 g of triethylamine in 2 g of water as formic acid extracting solution and 50 mg of 5 wt. %Pd/Al 2O 3 as a catalyst for hydrogenation. The reactor was sealed and pressurized with 30 bar of H 2 and 30 bar of CO 2. The reaction was heated to 30℃ for 17 h under continuous stirring. After reaction the products were analyzed by NMR and Ionic conductivity method. The amount of produced formic acid was 32 mg with concentration 0.35 M in aqueous solution. No other products of CO 2 hydrogenation was observed in the products.
  • EXAMPLE 8: Process at short time over Pd catalyst
  • Put in 50 ml stainless steel reactor 1 g of xylene and 1 g of octanol as organic phase with dissolved 50 mg of 2-ethyl-9, 10-anthraquinone (EQ) , 0.3 g of triethylamine in 2 g of water as formic acid extracting solution and 50 mg of 5 wt. %Pd/Al 2O 3 as a catalyst for hydrogenation. The reactor was sealed and pressurized with 30 bar of H 2 and 30 bar of CO 2. The reaction was heated to 60℃ for 1 h under continuous stirring. After reaction the products were analyzed by NMR and Ionic conductivity method. The amount of produced formic acid was 21 mg with concentration 0.22 M in aqueous solution. No other products of CO 2 hydrogenation was observed in the products.
  • EXAMPLE 9: Monophasic process over composite of metal catalyst and 2-ethyl-9, 10-anthraquinone (EQ) over Pd-Au catalyst
  • The catalyst was prepared by addition of 50 mg of 14 wt. %Pd-26 wt. %Au/C in the solution of 50 mg 2-ethyl-9, 10-anthraquinone (EQ) dissolved in 1 ml of xylene. Solvent was removed afterwards in the rotovap and the catalyst was dried at 80℃ in vacuum.
  • The catalyst was added in 50 ml stainless steel reactor together with 0.6 g of trimethylamine in 4 g of water as formic acid extracting solution. The reactor was sealed and pressurized with 30 bar of H 2 and 30 bar of CO 2. The reaction  was heated to 60℃ for 17 h under continuous stirring. After reaction the products were analyzed by NMR and Ionic conductivity method. The amount of produced formic acid was 115 mg with concentration 0.65 M in aqueous solution. No other products of CO 2 hydrogenation was observed in the products.
  • EXAMPLE 10: Monophasic process over composite of metal catalyst and 2-ethyl-9, 10-anthraquinone (EQ) over Pd catalyst
  • The catalyst was prepared by addition of 50 mg of 40 wt. %Pd/C in the solution of 50 mg 2-ethyl-9, 10-anthraquinone (EQ) dissolved in 1 ml of xylene. Solvent was removed afterwards in the rotovap and the catalyst was dried at 80℃ in vacuum.
  • The catalyst was added in 50 ml stainless steel reactor together with 0.9 g of trimethylamine in 6 g of water as formic acid extracting solution. The reactor was sealed and pressurized with 30 bar of H 2 and 30 bar of CO 2. The reaction was heated to 60℃ for 5 h under continuous stirring. After reaction the products were analyzed by NMR and Ionic conductivity method. The amount of produced formic acid was 154 mg with concentration 0.55 M in aqueous solution. No other products of CO 2 hydrogenation was observed in the products.
  • EXAMPLE 11: Monophasic process over composite of metal catalyst and 2-ethyl-9, 10-anthraquinone (EQ) over Pd catalyst
  • The catalyst was prepared by addition of 50 mg of 40 wt. %Pd/C in the solution of 100 mg 2-ethyl-9, 10-anthraquinone (EQ) dissolved in 1 ml of xylene. Solvent was removed afterwards in the rotovap and the catalyst was dried at 80℃ in vacuum.
  • The catalyst was added in 50 ml stainless steel reactor together with 0.9 g of trimethylamine in 6 g of water as formic acid extracting solution. The reactor was sealed and pressurized with 30 bar of H 2 and 30 bar of CO 2. The reaction was heated to 60℃ for 5 h under continuous stirring. After reaction the products were analyzed by NMR and Ionic conductivity method. The amount of produced formic acid was 2234 mg with concentration 0.81 M in aqueous solution. No other products of CO 2 hydrogenation was observed in the products.
  • EXAMPLE 12: Biphasic process over Pd catalyst and 2-ethyl-9, 10-anthraquinone (EQ) 
  • Put in 50 ml stainless steel reactor 1 g of xylene as organic phase with dissolved 100 mg of 2-ethyl-9, 10-anthraquinone (EQ) , 0.9 g of triethylamine in 6 g of water as formic acid extracting solution and 50 mg of 40 wt. %Pd/C as a catalyst for hydrogenation. The reactor was sealed and pressurized with 30 bar  of H 2 and 30 bar of CO 2. The reaction was heated to 60℃ for 1 h under continuous stirring. After reaction the products were analyzed by NMR and Ionic conductivity method. The amount of produced formic acid was 50 mg with concentration 0.18 M in aqueous solution. No other products of CO 2 hydrogenation was observed in the products.
  • Comparative EXAMPLE 2 : Biphasic process in the absence of 2-ethyl-9, 10-anthraquinone (EQ)
  • Put in 50 ml stainless steel reactor 1 g of xylene as organic phase with 0.9 g of triethylamine in 6 g of water as formic acid extracting solution and 50 mg of 40 wt. %Pd/C as a catalyst for hydrogenation. The reactor was sealed and pressurized with 30 bar of H 2 and 30 bar of CO 2. The reaction was heated to 60℃ for 1 h under continuous stirring. After reaction the products were analyzed by NMR and Ionic conductivity method. The amount of produced formic acid was 29 mg with concentration 0.1 M in aqueous solution. No other products of CO 2 hydrogenation was observed in the products.
  • EXAMPLE 13:
  • Put in 100 ml stainless steel reactor 15 g of toluene as organic solvent with dissolved 2 g of 2-ethyl-9, 10-anthraquinone (EQ) and 100 mg of Pd/Al 2O 3 as a catalyst for hydrogenation. The reactor was sealed and pressurized with 30 bar of H 2 and 30 bar of CO 2. The reaction was heated to 60℃ for 2 h under continuous stirring. After reaction the dark solid product has been separated, dissolved in 1 g of triethylamine (TEA) with 5 g of water and filtered from the catalyst. The liquid product has been heated at 60 ℃ under CO 2 pressure for 0.5 h. The amount of produced formic acid was 167 mg which corresponds to 45 % of EQ sites and the concentration of formic acid was 0.75 M. No other products of CO 2 hydrogenation was observed in the products.
  • EXAMPLE 14:
  • The test like in the example 13 has been repeated 3 times by recycling and reusing the metal catalyst. For the second, third and fourth cycle the amount of produced formic acid was 157, 149 and 152 mg. It indicates on high reproducibility of the results and high efficiency of the process.

Claims (18)

  1. A process for producing formic acid, comprising reacting carbon dioxide with hydrogen in the presence of a solvent, a substituted or non-substituted quinone compound and/or a substituted or non-substituted hydroquinone compound, and a catalyst comprising a metal chosen from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, Ir, Ni and Co.
  2. The process according to claim 1, wherein the substituted or non-substituted quinone compound, or the substituted or non-substituted hydroquinone compound has 5 to 20 carbon atoms.
  3. The process according to claim 1 or 2, wherein the substituted or non-substituted quinone compound, or the substituted or non-substituted hydroquinone compound comprises at least one cyclic ring.
  4. The process according to claim 3, wherein the substituted or non-substituted quinone compound, or the substituted or non-substituted hydroquinone compound comprises at least one five-membered or six-membered ring.
  5. The process according to claim 3, wherein the non-substituted quinone compound is chosen in the group consisting of 1, 2-benzoquinone, 1,4-benzoquinone, 1, 4-naphthoquinone, 9, 10-phenanthraquinone and 9, 10-anthraquinone.
  6. The process according to claim 3, wherein the non-substituted hydroquinone compound is chosen in the group consisting of benzene-1, 4-diol, benzene-1, 2-diol, naphthalene-1, 4-diol, phenanthrene-9, 10-diol and anthracene-9, 10-diol.
  7. The process according to claim 4, wherein the substituted quinone compound has the general formula (I) :
    wherein at least one of R 1, R 2, R 3, R 4, R 5, R 6, R 7 and R 8 is C 1-C 12 alkyl.
  8. The process according to claim 7, wherein the substituted quinone compound is chosen in the group consisting of 1-methyl-9, 10-anthraquinone, 2-methyl-9, 10-anthraquinone, 1-ethyl-9, 10-anthraquinone, 2-ethyl-9, 10-anthraquinone, 1-amyl-9, 10-anthraquinone and 2-amyl-9, 10-anthraquinone.
  9. The process according to claim 4, wherein the substituted hydroquinone compound has the general formula (II) :
    wherein at least one of R 1, R 2, R 3, R 4, R 5, R 6, R 7 and R 8 is C 1-C 12 alkyl.
  10. The process according to claim 9, wherein the substituted hydroquinone compound is chosen in the group consisting of 1-methylanthracene-9, 10-diol, 2-methylanthracene-9, 10-diol, 1-ethylanthracene-9, 10-diol, 2-ethylanthracene-9, 10-diol, 1-amylanthracene-9, 10-diol and 2-amylanthracene-9, 10-diol.
  11. The process according to any one of claims 1 to 10, wherein the catalyst is a supported metal catalyst comprising at least one metal element chosen from the group consisting of Pd, Pt, Ru and Au.
  12. The process according to claim 11, wherein the weight ratio of the substituted or non-substituted quinone compound and/or the substituted or non-substituted hydroquinone compound to the supported metal catalyst is in the range of 0.5 to 1.5.
  13. The process according to any one of claims 1 to 10, wherein the catalyst is Raney Ni.
  14. The process according to any one of claims 1 to 13, wherein the reaction medium comprises a basic compound.
  15. The process according to claim 1, wherein the solvent is a non-polar solvent and wherein the reaction results in the obtention of a solid comprising the catalyst and a reaction product, said process comprising the additional steps of:
    (i) separating the solid obtained from the reaction medium,
    (ii) adding a polar solvent to the separated solid to dissolve the reactionproduct,
    (iii) separating the catalyst from the solution so obtained, and
    (iv) exposing the solution obtained at step (iii) to a basic compound and then heating the solution.
  16. A process for producing formic acid, comprising the steps of:
    (i) mixing a substituted or non-substituted quinone compound and/or a substituted or non-substituted hydroquinone compound with a catalyst comprising a metal chosen from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, Ir, Ni and Co in the presence of a solvent,
    (ii) removing the solvent from the mixture obtained at step (i) , so as to obtain a solid composite, and
    (iii) reacting carbon dioxide with hydrogen in the presence of a solvent, the solid composite obtained at step (ii) , and optionally a basic compound.
  17. A composition comprising:
    (i) carbon dioxide,
    (ii) hydrogen,
    (iii) a solvent,
    (iv) a substituted or non-substituted quinone compound and/or a substituted or non-substituted hydroquinone compound, and
    (v)a catalyst comprising a metal chosen from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, Ir, Ni and Co.
  18. The composition according to claim 17, wherein the composition further comprises a basic compound.
EP18877890.6A 2017-11-15 2018-11-15 PROCESS FOR THE PRODUCTION OF FORMIC ACID Pending EP3710420A4 (en)

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Effective date: 20210707

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Ipc: C07C 51/00 20060101AFI20210701BHEP

Ipc: C07C 53/02 20060101ALI20210701BHEP