WO2009079713A1 - Procédé d'oxydation de composés organiques - Google Patents

Procédé d'oxydation de composés organiques Download PDF

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Publication number
WO2009079713A1
WO2009079713A1 PCT/AU2008/001904 AU2008001904W WO2009079713A1 WO 2009079713 A1 WO2009079713 A1 WO 2009079713A1 AU 2008001904 W AU2008001904 W AU 2008001904W WO 2009079713 A1 WO2009079713 A1 WO 2009079713A1
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ruo
nanoparticles
solution
oxide
oxidation
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PCT/AU2008/001904
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English (en)
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Ajit Pujari
Arati Kaza
Thomas Maschmeyer
Anthony Frederick Masters
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The University Of Sydney
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Priority claimed from AU2007907044A external-priority patent/AU2007907044A0/en
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Publication of WO2009079713A1 publication Critical patent/WO2009079713A1/fr

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    • 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
    • B01J23/46—Ruthenium, rhodium, osmium or iridium
    • B01J23/462—Ruthenium
    • 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
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/03—Catalysts comprising molecular sieves not having base-exchange properties
    • B01J29/0308—Mesoporous materials not having base exchange properties, e.g. Si-MCM-41
    • B01J29/0316—Mesoporous materials not having base exchange properties, e.g. Si-MCM-41 containing iron group metals, noble metals or copper
    • B01J29/0325—Noble metals
    • B01J35/23—
    • B01J35/393—
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/48—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by oxidation reactions with formation of hydroxy groups
    • C07C29/50—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by oxidation reactions with formation of hydroxy groups with molecular oxygen only
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
    • C07C45/27—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation
    • C07C45/32—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen
    • C07C45/33—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of CHx-moieties
    • 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
    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/10—After treatment, characterised by the effect to be obtained
    • B01J2229/20—After treatment, characterised by the effect to be obtained to introduce other elements in the catalyst composition comprising the molecular sieve, but not specially in or on the molecular sieve itself
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2601/00—Systems containing only non-condensed rings
    • C07C2601/12—Systems containing only non-condensed rings with a six-membered ring
    • C07C2601/14—The ring being saturated

Definitions

  • the invention relates to a method for oxidising organic compounds .
  • alkanes In alkanes, the carbon atoms have the maximum number of neighbouring carbon and hydrogen atoms. Due to the low reactivity of alkanes, the production of many industrially important compounds from alkanes involves the use of catalytic systems- for the oxidation of the alkane to form oxygen containing compounds. Nevertheless, due to the low reactivity of alkanes, as compared to the much higher reactivity of the oxidation products themselves, oxidation of alkanes generally results in a significant amount of overoxidised products. Furthermore, as only slight differences exist in the reactivity of the C-H bonds to free radicals, indiscriminate attack frequently results along the alkane chain.
  • the conventional industrial processes for producing cyclohexanol and cyclohexanone from cyclohexane using molecular oxygen employ a cobalt salt or a metal -boric acid as a catalyst . These processes are carried out as a homogeneous process and typically give about 4% conversion and 70 to 85% selectivity to cyclohexanol and cyclohexanone at 150 0 C under 1-2 MPa pressure.
  • the conventional industrial processes have a number of disadvantages. These disadvantages include the low conversion to the desired products. Further, because the process is homogeneous it is difficult and relatively expensive to recover the catalyst from the waste products. These processes also have high operating costs.
  • the inventors have found that nanoparticles of RuO 2 catalyse the oxidation of organic compounds by an oxidant. This is surprising as ruthenium is very oxophilic and therefore ruthenium oxide would not be expected to catalyse the oxidation of organic compounds by an oxidant.
  • the present invention provides a method of oxidising an organic compound, wherein the oxidation is catalysed by nanoparticles of RuO 2 .
  • the method comprises contacting the organic compound with an oxidant in the presence of the nanoparticles of RuO 2 .
  • the present invention provides a method of oxidising an organic compound, the method comprising contacting the organic compound with an oxidant in the presence of nanoparticles of RuO 2 , wherein the nanoparticles of RuO 2 catalyse the oxidation of the organic compound by the oxidant .
  • the organic compound is mixed with the oxidant and resultant mixture contacted with the nanoparticles of RuO 2 .
  • the organic compound may, for example, be a hydrocarbon.
  • the organic compound is an alkane, for example, cyclohexane.
  • the oxidant may be molecular oxygen (O 2 ) , hydrogen peroxide (H 2 O 2 ) , an organic peroxide, such as tert -butyl hydrogen peroxide (tBHP) , or any other oxidant known in the art.
  • O 2 molecular oxygen
  • H 2 O 2 hydrogen peroxide
  • tBHP tert -butyl hydrogen peroxide
  • the oxidant is molecular oxygen
  • hydrogen peroxide or an organic peroxide is typically used as a co-oxidant.
  • the nanoparticles of RuO 2 have a particle size in the range of from 2 to 20 nm, e.g. from 2 to 5 nm. In some embodiments, the nanoparticles of RuO 2 have a particle size in the range of from 2 to 10 nm.
  • the nanoparticles of RuO 2 are stabilised to inhibit the aggregation of the nanoparticles of RuO 2 .
  • the RuO 2 nanoparticles may be stabilised by being supported in an oxide matrix or supported on the surface of an oxide matrix.
  • the oxide matrix may be a metal oxide matrix or a metalloid oxide matrix (such as a silica matrix) .
  • the oxide matrix may, for example, be selected from silica, titanium oxide, aluminium oxide or zirconium oxide, or a mixture thereof. In some embodiments, the oxide matrix is a silica matrix.
  • Nanoparticles of RuO 2 supported in an oxide matrix can be prepared by a method comprising the steps of: a) subjecting a solution comprising a Ru salt, one or more precursor compounds of the formula M(OR) n , wherein M is Ti, Al, Zr or Si, each R may be the same or different and is H or alkyl, and n is 3 or 4, and an ionic surfactant, to conditions under which the one or more precursor compounds react to form an oligomer; and b) calcining the product of the preceding step to form an oxide matrix comprising nanoparticles of RuO 2 .
  • the ionic surfactant may be any ionic surfactant.
  • the ionic surfactant is typically an ionic liquid, more typically a room temperature ionic liquid.
  • the ionic surfactant when the ionic surfactant is an ionic liquid, the ionic liquid may act as a solvent and, in such embodiments, the solution may not comprise a further solvent. However, in some embodiments, the solution may comprise an ionic liquid and another solvent (e.g. water) .
  • another solvent e.g. water
  • the solvent may, for example, be water.
  • the one or more precursor compounds are selected from Si(OR) 4 , Ti(OR) 4 , Ti(OR) 3 , Al(OR) 3 and Zr(OR) 4 where each R may be the same or different and is H or alkyl .
  • the one or more precursor compounds are selected from Si(OR) 4 , Ti(OR) 4 , Ti(OR) 3 , Al(OR) 3 and Zr(OR) 4 where each R may be the same or different and is alkyl.
  • the one or more precursor compounds is Si(OEt) 4 , Si(OMe) 4 or Si(OBu) 4 (tetrabutoxy silane) or a mixture thereof.
  • R is Ci- 6 alkyl, more typically Ci -4 alkyl.
  • R is methyl, ethyl, propyl or butyl.
  • the precursor compound is tetraethoxysilane .
  • the ruthenium salt is a ruthenium halide (e.g. RuCl 3 ) .
  • Step a) comprises subjecting the solution to conditions under which the one or more precursor compounds react to form an oligomer.
  • the reaction of the precursor compounds in the solution to form an oligomer is similar to the reactions involved in a conventional sol-gel process. It is well within the skill of a person of ordinary skill in the art to determine the conditions under which the one or more precursor compounds will react to form an oligomer.
  • step a) comprises subjecting the solution to conditions under which the precursor compounds undergo condensation reactions to form an oligomer. This step may comprise leaving the solution at ambient temperature (i.e. room temperature, e.g. about 15-25°C) or above ambient temperature for a period of time sufficient for the condensation reactions to occur.
  • ambient temperature i.e. room temperature, e.g. about 15-25°C
  • at least some of the water or alcohol produced by the condensation reactions is removed from the reaction mixture, for example, by heating the reaction mixture or subjecting the reaction mixture to reduced pressure to evaporate at least some of the water or alcohol .
  • step a) comprises subjecting the solution to conditions under which the precursor compounds undergo hydrolysis and condensation reactions to form an oligomer. These reactions comprise the hydrolysis of an alkoxy group of a precursor compound followed by a condensation reaction between the hydrolysed precursor compound and another optionally hydrolysed precursor compound.
  • the hydrolysis reaction may be either base catalysed or acid catalysed. Accordingly, when the one or more precursor compounds do not include a hydroxy group (i.e. all the R groups are alkyl) , step a) may comprise incorporating an acid or base into the solution to catalyse the hydrolysis reaction and leaving the solution at ambient temperature (i.e. room temperature, e.g. about 15-25°C) or above ambient temperature for a period of time sufficient for the hydrolysis and condensation reactions to occur. Typically, during step a) , at least some of the water or alcohol produced by the condensation reactions is removed from the reaction mixture, for example, by heating the reaction mixture or subjecting the reaction mixture to reduced pressure to evaporate at least some of the water or alcohol .
  • the method further comprises a further step, before step b) , of removing at least some of the water or alcohol produced by the condensation reactions and at least some of the solvent, if any, from the product of step a) .
  • this step comprises heating the product of step a) or subjecting the product of step a) to reduced pressure to evaporate at least some of the water, alcohol or solvent.
  • nanoparticles of RuO 2 supported on the surface of an oxide matrix may be formed by:
  • step (b) calcining the product of step (a) to form nanoparticles of RuO 2 On the surface.
  • the present invention provides nanoparticles of RuO 2 when used to catalyse the oxidation of an organic compound.
  • the present invention provides nanoparticles of RuO 2 supported on or in an oxide matrix when used to catalyse the oxidation of an organic compound .
  • alkyl refers to a straight chain or branched alkyl.
  • the alkyl is a Ci to C 6 alkyl .
  • straight chain and branched alkyl include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl , isopentyl, sec-pentyl, 1,2- dimethylpropyl , 1 , 1-dimethylpropyl , hexyl , 4-methylpentyl , 1-methylpentyl, 2-methylpentyl , 3-methylpentyl , 1,1- dimethylbutyl , 2 , 2-dimethylbutyl , 3 , 3-dimethylbutyl , 1,2- dimethylbutyl , 1 , 3-dimethylbutyl , 1 , 2 , 2-trimethylpropyl and 1, 1, 2-trimethylpropyl
  • the present invention provides a method of oxidising organic compounds.
  • the method may be used to oxidise saturated or unsaturated hydrocarbon compounds to form compounds such as alcohols and ketones.
  • the organic compound may be any organic compound which contains an aliphatic carbon.
  • the organic compound may, for example, be any organic compound which contains an alkyl group .
  • the organic compound is an acyclic or cyclic hydrocarbon.
  • the organic compound is an alkane, such as a C 1 to C 20 alkane, an alkene, such as a C 2 to C 2 o alkene, or an alkyne, such as a C 2 to C 20 alkyne.
  • the organic compound is an acyclic Ci to Ci 2 alkane or a cyclic C 5 to C i2 alkane .
  • organic compounds include acyclic or cyclic, including aromatic, compounds containing one or more heteroatoms (e.g. 0, N, S or P) , such as ketones and alcohols.
  • the organic compound may be substituted or unsubstituted, e.g. with one or more halides (F, Cl, Br or I) -
  • nanoparticles are particles having a particle size in the nanometre size range, i.e. between 1 and 1000 nm.
  • Nanoparticles of RuO 2 are nanoparticles having the stoichiometry RuO 2 and having a solid state structure recognised as that of ruthenium oxide.
  • the structure of ruthenium oxide (RuO 2 ) has been published by J Hanies et al (Acta Cryst B 53(1997) 880) .
  • the structure of RuO 2 extends in three dimensions and is based on the repetition of a unit cell in three dimensions.
  • the unit cell of RuO 2 can be determined from the crystal structure. Each unit cell has one ruthenium at each corner of the unit cell and one in the middle of - S - the unit cell.
  • each corner Since each corner is shared by 8 unit cells, each corner atom contributes 1/8 of a ruthenium atom to the unit cell.
  • the unit cell therefore contains the equivalent of 2 ruthenium atoms.
  • the oxidation state of the ruthenium atoms in the unit cell is plus 4.
  • the nanoparticles of RuO 2 are typically stabilised in or on an oxide matrix.
  • stabilized in or on an oxide matrix it is meant that the nanoparticles of RuO 2 are supported in an oxide matrix, or are supported on the surface of an oxide matrix, in a manner which maintains the nanoparticles of RuO 2 as discrete nanoparticles.
  • the nanoparticles of RuO 2 do not agglomerate into larger sized particles of RuO 2 .
  • RuO 2 nanoparticles stabilised in an oxide matrix may be prepared by preparing a mesoporous oxide matrix using an ionic surfactant template in the presence of a Ru salt .
  • This method comprises the steps of: a) subjecting a solution comprising a Ru salt, one or more precursor compounds of the formula M(0R) n # wherein M is Ti, Al, Zr or Si, each R may be the same or different and is H or alkyl, and n is 3 or 4, and an ionic surfactant, to conditions under which the one or more precursor compounds of the formula M(OR) n react to form an oligomer; b) calcining the product of the preceding step to form an oxide matrix comprising nanoparticles of RuO 2 .
  • the interaction between the oligomer and the surfactant micelles results in the formation of an organic-inorganic composite gel material.
  • the organic- inorganic composite gel material is then calcined to form an oxide matrix comprising RuO 2 nanoparticles.
  • the resultant oxide matrix is a mesoporous oxide matrix comprising nanoparticles of RuO 2 dispersed in the oxide matrix.
  • the ionic surfactant may be any ionic surfactant.
  • the ionic surfactant is typically an ionic liquid, more typically a room temperature ionic liquid, that is, an ionic surfactant that is liquid at room temperature.
  • the solution comprises an ionic liquid and another solvent (e.g. water) .
  • another solvent e.g. water
  • the solution may be prepared by dissolving the Ru salt and the one or more precursor compounds in the ionic liquid in any order.
  • the solution comprises an ionic liquid and another solvent, the solution may be prepared by mixing the Ru salt, the one or more precursor compounds, the ionic liquid and the other solvent in any order.
  • the solution further comprises a solvent, e.g. water, and the solution may be prepared by dissolving the Ru salt, the one or more precursor compounds and the ionic surfactant in the solvent in any order.
  • the ionic surfactant acts as a template.
  • Ionic surfactants comprise an organic component.
  • the oligomers formed by the precursor compounds form a matrix around surfactant micelles in the solution resulting in an organic-inorganic composite gel material incorporating the Ru salt.
  • the surfactant is subsequently removed by the calcination step, resulting in a mesoporous oxide matrix with RuO 2 nanoparticles dispersed in the oxide framework.
  • the reaction of the precursor compounds to form the oligomer includes condensation reactions which produce water or an alcohol .
  • the method typically includes a step prior to the calcination step, of removing at least some of the water and alcohol produced by the condensation reactions, and at least some of the solvent if a solvent is used, from the organic- inorganic composite gel material .
  • this step comprises heating the organic- inorganic composite gel material or subjecting the organic-inorganic composite gel material to reduced pressure to evaporate at least some of the water, alcohol or solvent .
  • Suitable ionic surfactants include the room temperature ionic liquids containing the organic cations: quaternary ammonium, imidazolium, pyridinium, phosphorium, guanidinium, picolinium, piperazinium, pyrazolium, pyrrolidinium, triazinium or triazolium.
  • suitable ionic surfactants include Ci 6 mimBr and
  • the Ru salt and precursor compounds are included in the solution in a weight ratio of Ru: precursor compounds of about 0.1 to 10:100, that is, 1:1000 to 1:10.
  • the precursor compounds are one or more compounds of the formula M(OR) n where M is Ti, Al, Zr or Si, each R may be the same or different and is alkyl, and n is 3 or 4.
  • step a) comprises subjecting the solution to conditions under which the precursor compounds undergo hydrolysis and condensation reactions to form an oligomer.
  • an alkoxy (OR) group of a precursor compound is hydrolysed by reaction with water to form a hydroxy group and an alcohol .
  • the hydrolysis reaction may be acid or base catalysed.
  • a hydrolysed precursor compound reacts with an alkoxy group of another precursor compound or a hydroxy group of another hydrolysed precursor compound.
  • the hydrolysis and condensation reactions are usually concurrent and result in the formation of an oligomer.
  • the hydrolysis of the one or more precursor compounds may be catalysed by an acid or a base catalyst .
  • a base is included in the solution so that the pH of the solution is typically in the range from 9.5 to 12.5.
  • Suitable bases to catalyse the hydrolysis reaction include sodium hydroxide, potassium hydroxide, NH 3 -H 2 O, tetramethylammomium hydroxide (TMAOH, (CH 3 J 4 NOH) and tetraethylammonium hydroxide (TEAOH, (C 2 Hs) 4 NOH) .
  • the base is sodium hydroxide, potassium hydroxide, tetramethylammomium hydroxide or tetraethylammonium hydroxide.
  • the hydrolysis and resulting cross-linking of the precursor compounds are reversible. Accordingly, when the hydrolysis is base catalysed, the solution is typically heated or subjected to reduced pressure to remove at least some of the water or alcohol formed by the condensation reaction.
  • step a) comprises including a base in the solution to adjust the pH of the solution to 9.5 to 12.5, and heating the solution or subjecting the solution to reduced pressure.
  • the hydrolysis of the precursor compounds may also be acid catalysed.
  • the hydrolysis may be acid catalysed by including a strong acid such as HCl, HN0 3 , HBr, HI, H 2 SO 4 , H 3 PO 4 or acetic acid in the solution.
  • a strong acid such as HCl, HN0 3 , HBr, HI, H 2 SO 4 , H 3 PO 4 or acetic acid in the solution.
  • the pH of the solution is below 1.
  • step a) comprises including an acid in the solution to adjust the pH of the solution to below 1, and optionally heating the solution or subjecting the solution to reduced pressure.
  • the organic -inorganic composite gel matrix is calcined at about 550 0 C for about 10 hours at a ramp of 5°C per minute under air.
  • the solution includes more than one Ru salt. In some embodiments, the solution includes more than one ionic surfactant .
  • the one or more precursor compounds are one or more compounds of the formula M(OR) n , where M is Ti, Al, Zr or Si, each R may be the same or different and is alkyl and n is 3 or 4.
  • a homogenous solution of the Ru salt in an ionic liquid is formed.
  • the precursor compound or compounds and water are then added.
  • the resultant mixture is a solution of the Ru salt, the ionic surfactant and the one or more precursor compounds in water.
  • An acid or base is added to the solution to catalyse the hydrolysis of the one or more precursor compounds.
  • the one or more precursor compounds then undergo hydrolysis catalysed by the acid or base catalyst and condensation reactions and are transformed to a sol of oligomers.
  • the cooperative assembly and aggregation of the oligomers forms an organic- inorganic composite gel material.
  • micro-phase separation and continuous condensation of the oligomers occur.
  • Subsequent solidification and reorganisation further proceed to form an ordered meso- structure .
  • Hydrothermal treatment is then carried out to induce the complete condensation and solidification and improve the organisation.
  • the resultant product is then cooled to room temperature, filtered, washed and dried.
  • a mesoporous oxide matrix comprising RuO 2 nanoparticles is finally obtained by removing the surfactant by calcination.
  • TEM Transmission electron microscope
  • nanoparticles of RuO 2 supported on the surface of an oxide matrix may be formed by a method comprising the steps of:
  • step (b) calcining the product of step (a) to form nanoparticles of RuO 2 on the surface.
  • the inventors have found that RuO 2 nanoparticles on the surface of an oxide matrix formed by this method are immobilised on the surface and thus do not aggregate to form larger particles.
  • the ionic surfactant is an ionic liquid
  • the ionic liquid may act as a solvent and, in such embodiments, the solution may not comprise a further solvent.
  • the solution typically comprises an ionic liquid and another solvent, typically water.
  • the solution may be prepared by dissolving the Ru salt in the ionic liquid.
  • the solution comprises an ionic liquid and another solvent, the solution may be prepared mixing the Ru salt, ionic surfactant and other solvent in any order.
  • the solution further comprises a solvent, e.g. water, and the solution may be prepared by dissolving the Ru salt and ionic surfactant in the solvent in any order.
  • the method typically comprises a step, prior to the calcination step, of removing at least some of the solvent from the solution.
  • the surface of the oxide matrix may, for example, be the surface of particles of silica, titanium oxide, aluminium oxide or zirconium oxide. Typically the surface is a silica surface.
  • the surface of the oxide matrix may be the surface of a particulate metal or metalloid oxide such as silica particles.
  • the particles of the particulate metal or metalloid oxide have a particle size of about 0.5 to 1 micron.
  • step (a) typically comprises adding the particulate metal or metalloid oxide to the solution to form a slurry.
  • the resultant slurry is then dried to remove at least some of the solvent (if a solvent is used) and then calcined to form RuO 2 nanoparticles on the surface of the particulate metal or metalloid oxide.
  • the solution includes more than one Ru salt. In some embodiments, the solution includes more than one ionic surfactant.
  • TEM Transmission electron microscope
  • the RuO 2 nanoparticles supported in or on an oxide matrix can be used as a heterogeneous catalyst for the oxidation of organic compounds.
  • the catalyst can more readily be recovered from the reaction mixture than a homogenous catalyst.
  • the RuO 2 nanoparticles supported in or on an oxide matrix can be prepared by the relatively simple and environmentally safe processes described above. Further, the RuO 2 nanoparticles supported in or on an oxide matrix are relatively environmentally benign.
  • the inventors believe that nanoparticles of RuO 2 surprisingly catalyse the oxidation of organic compounds because the relatively small particle size provides a greater proportion of the RuO 2 that is present at the surface of the particles, where the reactions can occur, compared to larger particle sizes.
  • the inventors also postulate that the reactivity of the surface of the nano-sized particles of RuO 2 is unexpectedly different from that of the surfaces of larger particles .
  • the oxidation reaction catalysed by the RuO 2 nanoparticles may be carried out by contacting the organic compound with an oxidant in the presence of RuO 2 nanoparticles supported in or on an oxide matrix at a temperature and pressure whereby the RuO 2 nanoparticles catalyse the oxidation reaction.
  • the oxidant is used in an amount which provides at least a stoichiometric amount of oxygen relative to the organic compound.
  • the catalyst is used in an amount which provides a molar ratio of the organic compound to catalyst (moles of Ru) of about 10:1 to about 1000:1.
  • the oxidation reaction catalysed by RuO 2 nanoparticles may be carried out under a wide range of temperatures and pressures. However, for the reaction to be carried out in a commercially acceptable time period, the oxidation reaction is typically carried out at above ambient temperature, for example, at about 50° C to about 150 °C. In some embodiments, the reaction is carried out at about 75 "C.
  • the oxidant is O 2
  • the organic compound is typically contacted with the O 2 at above atmospheric pressure, for example, between about 1 to 100 bar, typically between about 2 to 50 bar. In some embodiments, the reaction is carried out at about 4 bar.
  • the oxidant is molecular O 2
  • hydrogen peroxide or organic peroxide is used as a co-oxidant.
  • the co-oxidant facilitates the formation of free radicals which initiate the reactions leading to the oxidation products.
  • the co-oxidant is present in the range of a trace amount to a slight excess (compared with the molecular O 2 ) , depending on the pressure at which the reaction is carried out.
  • RuO 2 nanoparticles may be used to catalyse the oxidation of organic compounds.
  • the organic compound is an alkane .
  • the alkane is a cyclic alkane such as cyclopentane, cyclohexane, cyclooctane, cyclododecane, etc.
  • the organic compound is an alkyl substituted aromatic such as methylbenzene (i.e. toluene) or p-tert-butyl toluene.
  • the organic compound is an alkene or an alkyne (including cycloalkenes and cycloalkynes) or an aromatic compound substituted with an alkene or alkyne group .
  • RuO 2 nanoparticles are particularly advantageous in catalysing the oxidation of cyclohexane, exhibiting relatively high conversion (up to 9 to 10% by weight) and very high selectivity to cyclohexanol and cyclohexanone (90 to 95% by weight) at
  • the use of the RuO 2 nanoparticles as a catalyst in the oxidation of cyclohexane can result in higher yields of cyclohexanone and cyclohexanol than the conventional industrial processes for oxidising cyclohexane to cyclohexanone and cyclohexanol using a cobalt salt or metal -boric acid catalyst.
  • no pre- treatment of the catalyst is required.
  • the inventors note that the catalysts used in conventional industrial cyclohexane oxidation processes can be used to catalyse the oxididation of other organic compounds. Furthermore, the inventors have found that when RuO 2 nanoparticles are used to catalyse the oxidation of cyclohexane to cyclohexanol and cyclohexanone, some overoxidation to carboxylic acid is observed, thus demonstrating the ability of RuO 2 nanoparticles to catalyse the oxidation of ketones and alcohols. It is therefore reasonable to expect that RuO 2 nanoparticles will catalyse the oxididation of organic compounds including alkanes, ketones, alcohols, and the other classes of organic compounds referred to above .
  • RuCl 3 . xH 2 0 was used as received from Stem Chemicals. This product contains 39.99% by weight Ru.
  • Type B Acidic synthesis RuCl 3 .xH 2 O (0.0284 g) in ethanol (3-4 mL) was added to bis (Cigtnim) PF 6 ionic liquid and stirred at room temperature for 30 min. To this solution a mixture of 10.0 g of 2M HCl and 4.0 g of H 2 O was added dropwise under constant stirring at 333 K for 3 h. 2.08 g TEOS was then added under constant stirring. The mixture was left stirring for 24 h, after which the yellowish solid was filtered and washed with water to remove the free ruthenium species from the mesoporous silicate surface. The material was then dried at 170 0 C for 5 h and calcined at 400 0 C for 12 h in air, to remove the organic template. This process was carried out three times to prepare samples 1, 2 and 3.
  • TUD-I is a mesoporous silica with a three dimensional pore system (surface area 500-1000 m 2 g "1 ; pore volume 0.5-2.2 cm 3 g "1 ; pore size 25-300 A 0 ) .
  • TUD-I was synthesised by aging, drying, and calcining a homogeneous synthesis mixture consisting of tetraethyl orthosilicate (TEOS) and triethanolamine (TEA) as described in Jansen, J. C; Shah, Z.; Marchese, L.; Zhou, W.; Puil, N.; Maschmeyer, T., Chem.Commun 2001, 713.
  • TEA tetraethyl orthosilicate
  • TOA triethanolamine
  • RuCl 3 .xH 2 O (0.0514 g) in acetonitrile (3 mL) was added to C 4 mim.PF 6 (0.25 mL) and stirred at room temperature for 15 min.
  • TUD-I (2.0 g) prepared as described above was then added to the mixture and a slurry was obtained. The slurry was stirred for 2 hr and solvent removed under vacuum and the dry material calcined at 250 0 C for 10 hours to get the powder of RuO 2 immobilized on the surface of the TUDl.
  • the size of the RuO 2 particles on this catalyst was determined by HR-TEM to be between 5-10 ran.
  • Oxidation reactions were carried out in a high pressure reactor.
  • the reaction mixture consisted of 50 mg RuO 2 - silica catalyst (Types A, B and C described above), 11.2 mmol cyclohexane, 5.9 mmol tBHP (70wt% in water) and 5.08 mmol of chlorobenzene as internal standard.
  • the reaction was carried out at 80°C and under 50 bar (5 MPa) of 9% O 2 in N 2 . After 6 hr, the pressure was released and the reactor was cooled to room temperature. The contents of the reactor were treated with triphenylphosphine at room temperature with stirring for 30 min to ensure complete decomposition of the peroxides.
  • the oxidation products were analysed and quantified by GC' and GC/MS . The results are set out in Table 1.
  • Comparative experiments were carried out under similar conditions.
  • the reaction mixture consisted only of cyclohexane, chlorobenzene and O 2 .
  • the reaction mixture consisted only of cyclohexane, chlorobenzene, O 2 and tBHP (co-oxidant) .
  • Catalyst Types A and B the percent conversion and the selectivity to cyclohexanone and cyclohexanol observed are higher than those obtained in the conventional industrial processes for producing cyclohexanol and cyclohexanone from cyclohexane using molecular oxygen and a cobalt salt or metal -boric acid catalyst.
  • Catalyst Type C the selectivity to cyclohexanone and cyclohexanol observed was higher than that obtained in the conventional industrial processes for producing cyclohexanol and cyclohexanone from cyclohexane using molecular oxygen and a cobalt salt or metal -boric acid catalyst.
  • RuO 2 nanoparticles therefore provide the potential for a cost effective and relatively environmentally benign process for the preparation of cyclohexanone and cyclohexanol from cyclohexane.

Abstract

L'invention concerne un procédé d'oxydation d'un composé organique, l'oxydation étant catalysée par des nanoparticules de RuO2. L'invention concerne également des procédés pour former les nanoparticules de RuO2.
PCT/AU2008/001904 2007-12-24 2008-12-23 Procédé d'oxydation de composés organiques WO2009079713A1 (fr)

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AU2007907044A AU2007907044A0 (en) 2007-12-24 Oxidation catalyst
AU2007907044 2007-12-24

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011079908A1 (fr) * 2009-12-29 2011-07-07 Leibniz-Institut Für Neue Materialien Gemeinnützige Gmbh Synthèse de nanoparticules au moyen de liquides ioniques
WO2011012226A3 (fr) * 2009-07-25 2012-03-01 Bayer Materialscience Ag Procédé de production de chlore par oxydation en phase gazeuse sur catalyseurs au ruthénium supportés nanostructurés

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1807380A (zh) * 2006-02-23 2006-07-26 华南理工大学 醇的液相催化氧化方法及其催化剂的再生方法

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1807380A (zh) * 2006-02-23 2006-07-26 华南理工大学 醇的液相催化氧化方法及其催化剂的再生方法

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011012226A3 (fr) * 2009-07-25 2012-03-01 Bayer Materialscience Ag Procédé de production de chlore par oxydation en phase gazeuse sur catalyseurs au ruthénium supportés nanostructurés
WO2011079908A1 (fr) * 2009-12-29 2011-07-07 Leibniz-Institut Für Neue Materialien Gemeinnützige Gmbh Synthèse de nanoparticules au moyen de liquides ioniques
JP2013515603A (ja) * 2009-12-29 2013-05-09 ライプニッツ−インスティトゥート フィア ノイエ マテリアーリエン ゲマインニュッツィゲ ゲゼルシャフト ミット ベシュレンクタ ハフトゥンク イオン液体を用いるナノ粒子の合成
US9126848B2 (en) 2009-12-29 2015-09-08 Leibniz-Insitut fuer Neue Materialien gemeinnuetzige GmbH Synthesis of nanoparticles by means of ionic liquids
KR101772243B1 (ko) * 2009-12-29 2017-09-12 라이브니츠-인스티투트 퓌어 노이에 마테리알리엔 게마인누찌게 게엠베하 이온액을 이용한 나노입자의 합성

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