WO2013150305A2 - Procédé de production d'alcool - Google Patents

Procédé de production d'alcool Download PDF

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Publication number
WO2013150305A2
WO2013150305A2 PCT/GB2013/050881 GB2013050881W WO2013150305A2 WO 2013150305 A2 WO2013150305 A2 WO 2013150305A2 GB 2013050881 W GB2013050881 W GB 2013050881W WO 2013150305 A2 WO2013150305 A2 WO 2013150305A2
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nanoparticles
process according
catalyst
particle size
palladium
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PCT/GB2013/050881
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English (en)
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WO2013150305A3 (fr
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Shik Chi Edman Tsang
Cheng-Tar Wu
Kai Man YU
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Isis Innovation Limited
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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
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
    • B01J23/8906—Iron and noble metals
    • 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
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/60—Platinum group metals with zinc, cadmium or mercury
    • 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
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/62—Platinum group metals with gallium, indium, thallium, germanium, tin or lead
    • 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
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/63—Platinum group metals with rare earths or actinides
    • 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
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/74—Iron group metals
    • B01J23/755—Nickel
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B01J35/391—Physical properties of the active metal ingredient
    • B01J35/393—Metal or metal oxide crystallite size
    • 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
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/03—Precipitation; Co-precipitation
    • B01J37/031—Precipitation
    • B01J37/033—Using Hydrolysis
    • 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
    • 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
    • C07C29/60—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by elimination of -OH groups, e.g. by dehydration
    • 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
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

Definitions

  • the invention relates to a process for producing a monohydric alcohol by hydrogenolysis of a polyhydric alcohol, a catalyst for use in the process, and a process for producing the catalyst.
  • fermentation process is selective, being a bioprocess it has a limited temperature regime and is associated with low productivity.
  • monohydric alcohols such as methanol and ethanol can be formed selectively by direct catalytic hydrogenolysis of polyols.
  • the heterogeneous catalyst which can be prepared by co-precipitation from solution, contains a highly-dispersed metal phase and an iron oxide support, which can achieve the desired concerted C-C and/or C-0 bond breakage and C-H bond formation.
  • the catalyst can be used to form monohydric alcohols such as methanol and ethanol directly from biomass and biomass-derived polyols. It can also catalyse formation of monohydric alcohols from polyols made via oil or coal related technology. For instance, ethylene glycol made on a petrochemical site, e.g. by steam cracking naphtha, can subsequently be converted into methanol and/or ethanol by direct catalytic
  • the catalyst of the invention not only provides a route for producing lower alcohols from biomass, but it also provides petrochemical sites with more versatility in terms of the products that they can produce.
  • the invention provides a process for producing a monohydric alcohol by hydrogenolysis of a polyhydric alcohol, which process comprises treating a polyhydric alcohol with hydrogen in the presence of a solid catalyst, which solid catalyst comprises (a) iron oxide and (b) a metal which is a noble metal or nickel.
  • the metal is a noble metal.
  • the noble metal is palladium. Due to a unique metal-support interaction, the palladium in the preferred catalyst is highly dispersed on the iron oxide support and remains so even after heat treatments and after use of the catalyst.
  • the high dispersion which can ranges from small Pd-containing nanoparticles (i.e.
  • the invention further provides a catalyst which comprises (a) iron oxide and (b) nanoparticles, which nanoparticles comprise palladium.
  • the mean particle size of said nanoparticles is usually less than 5 nm, and more typically less than 3 nm, and usually the particle size distribution of the nanoparticles is such that at least 90 % of the nanoparticles have a particle size of less than 5 nm.
  • the catalyst also comprises individual atoms of the palladium metal dispersed on the surface of the iron oxide. These have been observed by high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM).
  • the catalyst of the invention may be prepared by a co-precipitation process, and particularly useful catalysts have been obtained in this way.
  • the invention further provides a process for producing a catalyst, which catalyst comprises iron oxide and nanoparticles, which nanoparticles comprise palladium, which process comprises:
  • a co-precipitation step comprising contacting (a) a solution, which solution comprises a palladium salt and an iron salt dissolved in a solvent, with (b) a base, to produce a precipitate, which precipitate comprises one or more compounds comprising said iron and said palladium;
  • a calcination step comprising calcining the precipitate by heating the precipitate in air.
  • the process further comprises: (4) a reduction step, comprising heating the calcined precipitate in the presence of 3 ⁇ 4.
  • the solvent used in step (1) is typically water.
  • the precipitate produced in step (1) generally comprises one or more hydroxide or oxide-hydroxide compounds comprising Pd and Fe.
  • the Pd atoms are usually atomically dispersed and bonded within a sol-gel like matrix, formed during the co-precipitation step, comprising an Fe-O-Fe network.
  • iron and palladium atoms are generally connected to one other via bridging oxygen atoms.
  • the precipitate produced in step (1) comprises a polymeric network comprising Pd atoms and Fe atoms bonded together via bridging oxygen atoms.
  • FIG. 1 A schematic representation of an example of such a network is shown in Fig. 1.
  • the formation of such a polymeric network, throughout which the Pd atoms are dispersed, facilitates the production of final catalysts in which both individual Pd atoms and small Pd- containing nanoparticles are finely dispersed on the iron oxide surface.
  • the invention further provides a catalyst which is obtainable by the process of the invention for producing a catalyst.
  • a catalyst which is obtainable by the process of the invention for producing a catalyst, as a catalyst for the hydrogenolysis of a polyhydric alcohol.
  • Fig. 1 is a schematic representation of the type of polymeric network which could be formed during the co-precipitation step (1) of the process of the invention for producing a catalyst.
  • the co-precipitated network comprises Pd and Fe atoms bonded together via bridging oxygen atoms.
  • the envisaged networks of -Pd-O-Fe- are thought to be created by hydrolysis and cross-condensation between -PdO- and -FeO- species.
  • Fig. 2 shows the performances of catalysts containing 5 wt % Pd supported on different oxides (prepared by co-precipitation) for the hydrogenolysis of ethylene glycol. For each catalyst, the % conversion of ethylene glycol is shown, as is the % selectivity for the various products obtained.
  • Fig. 3 shows a comparison of 5 wt % Rh and 5 wt % Pd respectively on iron oxide, for the hydrogenolysis of ethylene glycol.
  • Fig. 4 shows the change of gross selectivity over 5 wt % Pd on Fe 2 03 versus time in the batch- wise hydrogenolysis of ethylene glycol.
  • Fig. 5 shows time-fraction selectivity over 5 wt % Pd on Fe 2 0 3 at different periods in the batch-wise hydrogenolysis of ethylene glycol.
  • Fig. 6 shows the catalytic yields of methanol and ethanol obtained over fresh and reused 5 wt % Pd/Fe 2 0 3 catalysts in the hydrogenolysis of ethylene glycol under different temperatures.
  • Fig. 7 is a histogram of the particle size distribution of the metal nanoparticles on the surface of one example of a Pd/Fe 2 0 3 catalyst of the invention, as measured by high- resolution transmission electron microscopy (HRTEM). As can be seen from the histogram, the dark field HRTEM images showed a large number of particles in the range ca. 1.0-2.5 nm.
  • HRTEM transmission electron microscopy
  • Fig. 8a shows XRD patterns of the 5 wt% Pd/Fe 2 0 3 catalyst before (lower trace) and after (upper trace) hydrogenolysis of ethylene glycol at 195°C, 20 bar H 2 (RT).
  • Fig. 8b shows an enlarged region of the XRD, showing two small peaks in the trace for the catalyst after the hydrogenolysis reaction, corresponding to PdFe alloy rather than Pd.
  • Fig. 9 shows core level Fe 2p 3 / 2 spectra of Pd/Fe 2 0 3 catalysts with different alcohol selectivities due to different hydrogen pre-reduction times (lh, 5h, 48h) after reaction at 195°C for 24h.
  • the right-hand dashed line corresponds to the binding energy of Fe 2p 3/2 and the left-hand dashed line corresponds to Fe 2p 3/2 in PdFe alloy (literature values).
  • Fig. 10 shows core level Pd 3d 5/2 spectra of Pd/Fe 2 0 3 catalysts with different alcohols selectivities due to different hydrogen pre-reduction times (lh, 5h, 48h) after reaction at 195°C for 24h.
  • the dashed line on the right hand side corresponds to the binding energy of Pd 3d sn and the left-hand darker dashed line corresponds to Pd 3d / 2 in PdFe alloy (literature values).
  • Fig. 1 1 shows H 2 -TPR profiles of Fe 2 0 3 (peaks at ⁇ 350°C and ⁇ 600°C) and Pd/Fe 2 0 3 (peaks at ⁇ 120°C and ⁇ 600°C).
  • Fig. 12 shows 1 st and 2 nd repeated TPR profiles of Pd/Fe 2 0 3 in H 2 after the temperature programmed heating terminated at 200°C, as compared to the 2 nd TPR profile of Pd/Al 2 0 3 .
  • Fig. 13 shows the rate of methanol production as a function of ethylene glycol concentration, over the 5 wt% Pd/Fe 2 0 3 catalyst of the invention.
  • Fig. 14 shows the rate of methanol production as a function of H 2 pressure, over the 5 wt% Pd/Fe 2 0 3 catalyst of the invention.
  • Fig. 15 shows a plot of ln(k / L mol "1 hr "1 ) (y axis) versus 1/(T/K) (x axis) for the hydrogenolysis of ethylene glycol at 20 bar 3 ⁇ 4, for 24 hrs, at temperatures of 428, 448, 468 and 488 K, over the 5 wt% Pd/Fe 2 0 3 catalyst of the invention.
  • the polyhydric alcohol is treated with hydrogen in the presence of a solid catalyst, which solid catalyst comprises iron oxide and a metal which is a noble metal or nickel.
  • the catalyst is a hydrogenolysis catalyst.
  • the term "hydrogenolysis catalyst”, as used herein, means a catalyst which is capable of catalysing a hydrogenolysis reaction.
  • monohydric alcohol takes its normal meaning in the art, i.e. an alcohol with a single -OH group.
  • Examples of monohydric alcohols are methanol, ethanol, propanol, butanol and pentanol.
  • Monohydric alcohols which can be produced by the process of the invention include compounds of formula R-OH, wherein R is a C 1 -1 0 alkyl group. More typically, R is a C 1 -6 alkyl group. R may for instance be a C alkyl group. In a preferred embodiment, for instance, R is ethyl or methyl.
  • the process of the invention is for producing a monohydric alcohol of formula R-OH, wherein R is methyl or ethyl.
  • the monohydric alcohol is typically therefore methanol or ethanol.
  • more than one monohydric alcohol may be produced by the process of the invention, i.e. a mixture of products may be produced, which may comprise more than one monohydric alcohol.
  • a mixture of ethanol and methanol may for instance be produced.
  • a C O alkyl group is an unsubstituted, straight or branched chain saturated hydrocarbon radical having from 1 to 10 carbon atoms.
  • a CMO alkyl group may be methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl or decyl.
  • CMO alkyl groups include C 1 -6 alkyl groups, for example methyl, ethyl, propyl, butyl, pentyl or hexyl.
  • C 1-10 alkyl groups also include C 1 -4 alkyl groups, for example methyl, ethyl, i-propyl, n-propyl, t-butyl, s-butyl or n-butyl.
  • polyhydric alcohol as used herein, also takes its normal meaning in the art, i.e. an alcohol with two or more -OH groups.
  • a polyhydric alcohol may also be referred to as a "polyol”.
  • polyhydric alcohol and “polyol” are used herein interchangeably.
  • examples of polyhydric alcohols include sugar alcohols, for instance ethylene glycol, glycerol and longer-chain su ar alcohols of formula (I) below:
  • n is 0 or an integer equal to or greater than 1.
  • Sugars are also polyhydric alcohols.
  • polyhydric alcohols include monosaccharides, such as glucose, and other com ounds of formula (II) below:
  • n is an integer equal to or greater than 1.
  • Polyhydric alcohols also incude disaccharides, for instance sucrose, as well as oligosaccharides and polysaccharides.
  • polyhydric alcohols which are polysaccharides include, for instance, starch, amylose, amylopectin, glycogen, cellulose, pectin, chitin, laminarin, chrysolaminarin, xylan, arabinoxylan, mannan, fucoidan or galactomannan.
  • polyhydric alcohols which are polymers include polyethers and polyesters.
  • Polyethers and polyesters often comprise multiple terminal OH groups.
  • the term “noble metal” is used in chemistry to refer to a particular group of transition metals which have outstanding resistance to corrosion, namely the second and third row transition metals of groups 8 to 11 of the periodic table.
  • the term “noble metal”, as used herein, means a metal selected from the group consisting of ruthenium, rhodium, palladium, silver, osmium, iridium, platinum and gold.
  • the metal, which is a noble metal or nickel, in the solid catalyst used in the process of the invention is generally supported on the iron oxide.
  • the solid catalyst typically comprises a support material which comprises said iron oxide, wherein the metal is supported on said support material.
  • the catalyst usually comprises a metal, which is a noble metal or nickel, supported on iron oxide.
  • the solid catalyst comprises: (a) iron oxide; and (b) a metal, which is a noble metal or nickel, in the oxidation state 0.
  • the solid catalyst may, in this embodiment, further comprise said metal in an oxidation state other than 0, for instance in an oxidation state greater than 0, for instance an oxidation state of from +1 to +4.
  • the metal which is a noble metal or nickel, is typically present in the form of nanoparticles, supported on the iron oxide.
  • the catalyst used in the process of the invention for producing a monohydric alcohol typically comprises: (a) said iron oxide; and (b) nanoparticles which comprise said metal, which metal is a noble metal or nickel.
  • nanoparticle means a microscopic particle whose size is measured in nanometres (nm). Typically, a nanoparticle has a particle size of from 0.2 nm to 1000 nm, for instance from 0.5 nm to 1000 nm. A nanoparticle may be crystalline or amorphous. A nanoparticle may be spherical or non-spherical. Non-spherical nanoparticles may for instance be plate-shaped, needle-shaped or tubular.
  • particle size as used herein means the diameter of the particle if the particle is spherical or, if the particle is non-spherical, the volume-based particle size. The volume-based particle size is the diameter of the sphere that has the same volume as the non-spherical particle in question.
  • nanoparticles which comprise said metal are also referred to herein as clusters.
  • the iron oxide acts as a support material.
  • the nanoparticles which comprise said metal are supported on the iron oxide.
  • the nanoparticles are typically present on the surface of the iron oxide.
  • the metal in the nanoparticles which is a noble metal or nickel, is predominantly in metallic form, i.e. in the oxidation state 0.
  • the nanoparticles comprise said metal in the oxidation state 0.
  • the nanoparticles may however further comprise said metal in an oxidation state other than 0, for instance in an oxidation state greater than 0, for instance an oxidation state of from +1 to +4.
  • the nanoparticles consist of said metal, which metal is a noble metal or nickel.
  • nanoparticles which comprise said metal further comprise iron.
  • the catalyst may comprise nanoparticles which consist of said metal (which is a noble metal or nickel), and nanoparticles which comprise iron and said metal.
  • all, or substantially all, of the nanoparticles further comprise iron.
  • the nanoparticles may for instance consist of said metal (which is a noble metal or nickel) and iron.
  • the iron present in the nanoparticles may be present in the nanoparticles in metallic form, i.e. in the oxidation state 0.
  • the iron present in the nanoparticles is usually present in the form of an alloy with the noble metal.
  • said nanoparticles which further comprise iron comprise an alloy of said noble metal and iron.
  • the nanoparticles comprise an alloy of the noble metal and iron. In one embodiment, only some of the nanoparticles comprise an alloy of the noble metal and iron.
  • the catalyst may comprise
  • nanoparticles which consist of said noble metal and nanoparticles which comprise an alloy of the noble metal and iron.
  • all, or substantially all, of the nanoparticles comprise an alloy of the noble metal and iron.
  • the nanoparticles consist of said alloy of the noble metal and iron.
  • nanoparticles which further comprise iron are typically bimetallic
  • the nanoparticles are bimetallic nanoparticles which comprise (i) said metal which is a noble metal or nickel, and (ii) iron.
  • the mean particle size of the nanoparticles in the solid catalyst which is used in the process of the invention is less than 50 nm. More typically, however, the mean particle size of the nanoparticles is less than 20 nm; even more typically, it is less than 10 nm. Thus, for instance, the mean particle size of the nanoparticles in the solid catalyst may be from 1 nm to 50 nm, or for instance from 1 nm to 20 nm. It could for instance be from 1 nm to 10 nm. In some embodiments, however, the mean particle size of the nanoparticles is equal to or less than 1 nm.
  • the particle size distribution of said nanoparticles is such that at least 90 % of the nanoparticles have a particle size of less than 50 nm. More typically, at least 90 % of the nanoparticles have a particle size of less than 20 nm, or for instance less than 10 nm.
  • the mean particle size of the nanoparticles in the solid catalyst used in the process of the invention is less than 5 nm.
  • the mean particle size of said nanoparticles may for instance be less than 3 nm.
  • the mean particle size of the nanoparticles in the solid catalyst may for instance be from 1 nm to 5 nm, or for instance from 1 nm to 3 nm. In a particularly preferred embodiment, the mean particle size of the nanoparticles in the solid catalyst used in the process of the invention is from 1.0 nm to 2.5 nm. For instance, the mean particle size of said nanoparticles may be about 1.5 nm.
  • the particle size distribution of the nanoparticles in the solid catalyst used in the process of the invention is such that at least 90 % of the nanoparticles have a particle size of less than 5 nm.
  • the particle size distribution of said nanoparticles may be such that at least 90 % of the nanoparticles have a particle size of less than 3.5 nm. Such a distribution is shown in Fig. 7.
  • the metal which is a noble metal or nickel
  • the metal may also be present in the solid catalyst in the form of individual metal atoms.
  • the individual metal atoms are on the surface of the iron oxide.
  • the metal, which is a noble metal or nickel may be present in the solid catalyst which is used in the process of the invention both in the form of nanoparticles and in the form of single metal atoms dispersed on the iron oxide surface.
  • the solid catalyst further comprises individual atoms of said metal.
  • said individual atoms are dispersed on the surface of the iron oxide.
  • the mean particle size of said nanoparticles which comprise said metal, which is a noble metal or nickel is less than 4 nm
  • the particle size distribution of said nanoparticles is such that at least 90 % of the nanoparticles have a particle size of less than 5 nm
  • the catalyst further comprises individual atoms of said metal dispersed on the surface of the iron oxide.
  • the metal is a noble metal.
  • the polyhydric alcohol is treated with hydrogen in the presence of a solid catalyst, which solid catalyst comprises iron oxide and a noble metal.
  • the noble metal is selected from palladium and rhodium.
  • the metal may be selected from palladium, rhodium and nickel.
  • the noble metal is palladium or rhodium.
  • the polyhydric alcohol is treated with hydrogen in the presence of a solid catalyst, which solid catalyst comprises iron oxide and a noble metal selected from palladium and rhodium.
  • the noble metal is palladium
  • the polyhydric alcohol is treated with hydrogen in the presence of a solid catalyst, which solid catalyst comprises iron oxide and palladium.
  • the metal is palladium and the catalyst comprises (a) said iron oxide and (b) nanoparticles comprising said palladium.
  • the iron oxide can act as a support material.
  • the nanoparticles which comprise said palladium are supported on the iron oxide.
  • the palladium nanoparticles are typically present on the surface of the iron oxide.
  • the nanoparticles comprise said palladium in the oxidation state 0.
  • the nanoparticles may however further comprise palladium in an oxidation state other than 0, for instance in an oxidation state greater than 0, for instance an oxidation state of from +1 to +4.
  • Oxidation states greater than 0 for palladium include for instance +1, +2 and +4.
  • the nanoparticles consist of said palladium.
  • nanoparticles which comprise said palladium further comprise iron.
  • the catalyst may comprise nanoparticles which consist of palladium, and nanoparticles which comprise iron and palladium.
  • all, or substantially all, of the nanoparticles further comprise iron.
  • the nanoparticles may for instance consist of palladium and iron.
  • the iron present in the nanoparticles may be present in the nanoparticles in metallic form, i.e. in the oxidation state 0.
  • the iron present in the nanoparticles is usually present in the form of an alloy with the palladium.
  • said nanoparticles which further comprise iron comprise an alloy of palladium and iron.
  • some or all of said nanoparticles comprise an alloy of palladium and iron. In one embodiment, only some of the nanoparticles comprise an alloy of palladium and iron.
  • the catalyst may comprise nanoparticles which consist of palladium, and nanoparticles which comprise an alloy of palladium and iron. In another embodiment, all, or substantially all, of the nanoparticles comprise an alloy of palladium and iron. In some embodiments, the nanoparticles consist of said alloy of palladium and iron.
  • nanoparticles which further comprise iron are typically bimetallic
  • the nanoparticles in the catalyst used in the process of the invention are bimetallic nanoparticles which comprise (i) said palladium, and (ii) iron.
  • the mean particle size of the nanoparticles which comprise palladium is less than 20 nm; even more typically, it is less than 10 nm.
  • the mean particle size of the nanoparticles in the solid catalyst which comprise palladium may be within the range of from 1 nm to 20 nm, or for instance within the range of from 1 nm to 10 nm. It could for instance be from 1 nm to 7 nm. In some embodiments, however, the mean particle size of the nanoparticles is equal to or less than 1 nm.
  • the particle size distribution of said nanoparticles which comprise palladium is such that at least 90 % of the nanoparticles have a particle size of less than 20 nm. More typically, at least 90 % of the nanoparticles have a particle size of less than 10 nm, or for instance less than 7 nm.
  • the mean particle size of the nanoparticles which comprise palladium is less than 5 nm.
  • the mean particle size of said nanoparticles may for instance be less than 3 nm, or for instance less than 1 nm.
  • the mean particle size of the nanoparticles which comprise palladium may for instance be from 1 nm to 5 nm, or for instance from 1 nm to 3 nm.
  • the mean particle size of the nanoparticles which comprise palladium is from 1.0 nm to 2.5 nm.
  • the mean particle size of said nanoparticles may be about 1.5 nm.
  • the particle size distribution of the nanoparticles which comprise palladium in the solid catalyst used in the process of the invention is such that at least 90 % of the nanoparticles have a particle size of less than 5 nm.
  • the particle size distribution of said nanoparticles may be such that at least 90 % of the nanoparticles have a particle size of less than 3.5 nm. Such a distribution is shown in Fig. 7. In some
  • the particle size distribution of said nanoparticles may be such that at least 90 % of the nanoparticles have a particle size of equal to or less than 1 nm.
  • the palladium may also be present in the solid catalyst in the form of individual palladium atoms. Typically, the individual palladium atoms are on the surface of the iron oxide.
  • the solid catalyst which is used in the process of the invention may comprise palladium both in the form of said nanoparticles which comprise palladium, and in the form of single palladium atoms dispersed on the iron oxide surface.
  • the mean particle size of said nanoparticles which comprise palladium is less than 5 nm
  • the particle size distribution of said nanoparticles is such that at least 90 % of the nanoparticles have a particle size of less than 10 nm
  • the catalyst further comprises individual atoms of palladium dispersed on the surface of the iron oxide.
  • the mean particle size of said nanoparticles which comprise palladium is less than 4 nm
  • the particle size distribution of said nanoparticles is such that at least 90 % of the nanoparticles have a particle size of less than 5 nm
  • the catalyst further comprises individual atoms of palladium dispersed on the surface of the iron oxide.
  • the iron oxide in the solid catalyst used in the process of the invention for producing a monohydric alcohol comprises Fe 2 0 3 .
  • Fe 2 0 3 is typically formed during a calcination step in the preparation of the catalyst.
  • the iron oxide in the solid catalyst may further comprise other, more reduced forms of iron oxide, particularly if the catalyst has undergone a pre-reduction step during the preparation of the catalyst, or for instance if the catalyst is being re-used after having been exposed to hydrogen already in a hydrogenolysis process (such as the process of the invention for producing a monohydric alcohol by hydrogenolysis of a polyol). It is known that the reduction of bulk iron oxide by hydrogen proceeds through the following steps:
  • the iron oxide in the solid catalyst used in the process of the invention typically comprises Fe 2 0 3 . It may however further comprise Fe 3 0 4 or FeO (which may be present due to partial reduction of Fe 2 0 3 ) or a mixture of Fe 3 0 4 and FeO, in addition to the Fe 2 0 3 .
  • the solid catalyst used in the process of the invention may further comprise Fe, i.e. iron metal.
  • Fe may for instance be present in the form of an alloy with the noble metal or nickel in the nanoparticles, as explained above.
  • iron metal may be present in the catalyst in the form of nanoparticles consisting of iron metal.
  • the iron oxide in the catalyst used in the process of the invention has a surface which has undergone reduction.
  • Such surface reduction of iron oxide may for instance have occurred during a pre -reduction step during the preparation of the catalyst, or for instance if the catalyst is being re-used after having been exposed to hydrogen already in a hydrogeno lysis process (such as the process of the invention for producing a monohydric alcohol). It is thought that the reduction of the surface of the iron oxide (with the noble metal or nickel in close proximity) will give nanoparticles comprising (a) Fe and (b) the noble metal or nickel (for instance Fe and palladium). These small but catalytically active clusters are thought to offer much enhanced catalyst activity and selectivity due to electronic modification of band structure.
  • oxygen vacancies will be formed in close vicinity to the Fe/noble metal or Fe/Ni nanoparticles on the defective iron oxide surface due to the maintenance of electrical neutrality upon reduction (their presence may stabilize the clusters), which may further assist adsorption of the ethylene glycol molecule
  • the iron oxide in the solid catalyst which is used in the process of the invention for producing a monohydric alcohol typically comprises oxygen vacancies.
  • the oxygen vacancies are at or near the surface of the iron oxide.
  • the metal (which is a noble metal or nickel) is present in the solid catalyst in an amount which is equal to or less than 50 weight %, based on the weight of the iron oxide. More typically, the metal is present in an amount which is equal to or less than 30 weight %, based on the weight of the iron oxide. The metal may for instance be present in an amount which is equal to or less than 20 weight %, or for instance which is equal to or less than 10 weight %, based on the weight of the iron oxide. In some embodiments, for instance, the metal is present in an amount which is equal to or less than 8 weight %, based on the weight of the iron oxide.
  • the metal (which is a noble metal or nickel) is present in the solid catalyst in an amount of from 0.1 weight % to 50 weight %, based on the weight of the iron oxide. More typically, the metal is present in an amount of from 0.5 weight % to 30 weight %, based on the weight of the iron oxide. The metal may for instance be present in an amount of from 1 weight % to 20 weight %, or for instance from 2 weight % to 10 weight %. In some embodiments, for instance, the metal is present in an amount of from 2 weight % to 8 weight %, based on the weight of the iron oxide, for instance from 3 weight % to 7 weight %.
  • the metal is a noble metal.
  • the noble metal is rhodium or palladium.
  • the catalyst used in the process of the invention for producing a monohydric alcohol is a catalyst which comprises iron oxide and
  • nanoparticles which nanoparticles comprise palladium
  • catalyst is obtainable by a process of the invention as defined herein for producing such a catalyst.
  • the iron oxide in the catalyst used in the process of the invention may be doped with a dopant element. It is a finding of the invention that doping the iron oxide support of the catalyst with a dopant element can lead to further improvements in the activity and/or selectivity of the catalyst, when used in the process of the invention.
  • the dopant element is a metal other than iron, for instance a transition metal other than iron.
  • the dopant element, when present, is present in the catalyst in addition to said noble metal or nickel.
  • the dopant element, when present is typically other than said metal which is a noble metal or nickel. (That is to say, when the metal is a noble metal, the dopant is typically a metal other than iron and other than said noble metal, and when the metal is nickel, the dopant is typically a metal other than iron and other than nickel.)
  • the dopant element may for instance be a first row transition metal other than iron.
  • the dopant element may be selected from Sc, Ti, V, Cr, Mn, Co, Ni and Cu.
  • the dopant is selected from Sc, Ti, V, Cr, Mn, Co and Cu. More typically, it is selected from V, Cr, Mn, Co and Cu.
  • the dopant element is cobalt (Co).
  • Such dopant elements, and especially cobalt may provide further improvements in the activity and selectivity of the catalyst.
  • the iron oxide in the catalyst used in the process of the invention may or may not be doped with a dopant element.
  • the dopant element is preferably cobalt.
  • the catalyst used in the process of the invention comprises (a) cobalt-doped iron oxide and (b) said metal which is a noble metal or nickel.
  • the iron oxide may alternatively, of course, not be doped with a dopant element, i.e. the iron oxide may be undoped. Catalysts in which the iron oxide is not doped with a dopant element (i.e. in which the iron oxide is "undoped") are described in further detail hereinbelow, in the Example.
  • the catalysts of the invention can be used to produce monohydric alcohols from of a wide range of polyols, ranging from sugar alcohols such as ethylene glycol and glycerol, sugars, including polysaccharides such as starch, and other polymeric polyols, for instance polyester polyols and polyether polyols.
  • sugar alcohols such as ethylene glycol and glycerol
  • sugars including polysaccharides such as starch
  • other polymeric polyols for instance polyester polyols and polyether polyols.
  • the polyhydric alcohol is a sugar alcohol, a sugar or a polymer.
  • the polyhydric alcohol is a sugar alcohol, it is usually a sugar alcohol of formula (I)
  • n is 0 or an integer equal to or greater than 1.
  • the variable n may for instance be 0 or an integer of from 1 to 5,000.
  • n may for instance be 0 or an integer of from 1 to 1 ,000, or for example n may be 0 or an integer of from 1 to 100. More typically, n is 0 or an integer from 1 to 8.
  • the sugar alcohol of formula (I), from which a monohydric alcohol may be produced in accordance with the process of the invention has from 2 to 10 carbon atoms.
  • n is 0 or an integer from 1 to 8.
  • sugar alcohols of formula I) include, but are not limited to, the following compounds:
  • n is 0 or an integer of 1 to 6.
  • the sugar alcohol is selected from ethylene glycol (C2), glycerol (C3), butane- 1 ,2, 3, 4-tetrol (C4), pentane-l ,2,3,4,5-pentol (C5), hexane-l,2,3,4,5,6-hexol (C6), heptane-l ,2,3,4,5,6,7-heptol (C7), octane-l,2,3,4,5,6,7,8-octol (C8). More typically, n is 0, 1, 2, 3 or 4.
  • the sugar alcohol is selected from ethylene glycol (C2), glycerol (C3), butane- 1,2,3, 4-tetrol (C4), pentane- 1,2, 3,4,5- pentol (C5) and hexane- 1,2,3, 4,5, 6-hexol (C6).
  • n is 0, 1 or 2 and the sugar alcohol is selected from ethylene glycol (C2), glycerol (C3) and butane- 1,2,3, 4-tetrol (C4).
  • n 0 or 1
  • the sugar alcohol is ethylene glycol or glycerol.
  • n is 0 and the sugar alcohol is ethylene glycol.
  • the polyhydric alcohol is a sugar
  • it may for instance be a sugar which comprises a compound of formula II)
  • n is an integer equal to or greater than 1.
  • the sugar of formula (II), from which a monohydric alcohol may be produced in accordance with the process of the invention has from 3 to 10 carbon atoms.
  • typically m is an integer from 1 to 8.
  • sugars of formula (II) include the following compounds:
  • the polyhydric alcohol may alternatively be a sugar which is a disaccharide, for instance sucrose, or an oligosaccharide, for instance a sugar with from 3 to 10 saccharide units.
  • the polyhydric alcohol may be a sugar which is also a polymer, i.e. a polysaccharide.
  • the polysaccharide may for instance comprise starch, amylose, amylopectin, glycogen, cellulose, pectin, chitin, laminarin, chrysolaminarin, xylan, arabinoxylan, mannan, fucoidan or galactomannan, or a mixture or one or more thereof.
  • Polyhydric alcohols also include other kinds of polymers for instance polyethers and polyesters.
  • the polyhydric alcohol is a polymer which is a polysaccharide, a polyether or a polyester.
  • the polyhydric alcohol is ethylene glycol or glycerol. In one embodiment, the polyhydric alcohol is ethylene glycol.
  • the polyhydric alcohol is glycerol.
  • Monohydric alcohols which can be produced by the process of the invention include compounds of formula ROH, wherein R is a C 1-10 alkyl group.
  • the process of the invention is a process for producing a monohydric alcohol of formula ROH, wherein R is a CMO alkyl group. More typically, though, R is a Ci -6 alkyl group. Even more typically, R is methyl or ethyl.
  • the process of the invention is a process for producing a monohydric alcohol of formula ROH, wherein R is selected from the group consisting of methyl and ethyl.
  • R is selected from the group consisting of methyl and ethyl.
  • the monohydric alcohol is methanol or ethanol.
  • more than one monohydric alcohol may be produced by the process of the invention, i.e. a mixture of products may be produced by the process of the invention which mixture may comprise more than one monohydric alcohol.
  • the process is for producing a mixture comprising said monohydric alcohol (which may be termed a first monohydric alcohol) and a second monohydric alcohol, by hydrogenolysis of said polyhydric alcohol.
  • the first monohydric alcohol may for instance be methanol and the second monohydric alcohol may for example be ethanol.
  • the process of the invention for producing a monohydric alcohol may therefore be a process for producing methanol and ethanol.
  • the process is for producing methanol.
  • any other monohydric alcohol that is produced by the process may be considered to be a byproduct, and the process may further comprise a purification step to separate that byproduct from the desired monohydric alcohol, methanol.
  • the process is for producing ethanol.
  • any other monohydric alcohol produced by the process may be considered to be a by-product, and the process may further comprise a purification step to separate the by-product from the desired monohydric alcohol, ethanol.
  • the polyhydric alcohol is glycerol or ethylene glycol
  • monohydric alcohol is methanol or ethanol.
  • the polyhydric alcohol is ethylene glycol
  • the monohydric alcohol is methanol or ethanol.
  • the polyhydric alcohol is glycerol, and the monohydric alcohol is methanol or ethanol.
  • the step of treating the polyhydric alcohol with hydrogen is carried out in the presence or absence of a solvent, typically in the presence of a solvent.
  • the solvent when present, should be an inert solvent.
  • inert solvent means a solvent which does not itself undergo hydrogenolysis
  • the solvent cannot be an organic compound which would undergo C-C bond cleavage and hydrogenolysis during the present process.
  • the solvent when present, is typically an inorganic solvent.
  • the solvent is water.
  • the source of the hydrogen used in the process of the invention may be a solid or liquid hydrogen storage material.
  • the solid or liquid hydrogen storage material may be any suitable hydrogen storage material that is capable of providing or releasing hydrogen in a form which is suitable for hydrogenolysis.
  • the hydrogen is provided in the form of molecular hydrogen.
  • the hydrogen storage material may be a material which is capable of releasing molecular hydrogen, for instance hydrogen gas.
  • the hydrogen may be provided by the hydrogen storage material in another reactive form, for instance in the form of single hydrogen atoms (hydrogen atom radicals) or hydride anions.
  • the hydrogen used in the process of the invention may be provided by such a hydrogen storage material in situ.
  • the step of treating said polyhydric alcohol with hydrogen may comprise treating the polyhydric alcohol with a solid or liquid hydrogen storage material.
  • the step of treating said polyhydric alcohol with hydrogen may for instance comprise treating the polyhydric alcohol with a solid or liquid hydrogen storage material and generating the hydrogen in situ from said hydrogen storage material.
  • the process of the invention may comprise generating said hydrogen from a solid or liquid hydrogen storage material.
  • the process of the invention comprises generating said hydrogen in situ from a solid or liquid hydrogen storage material.
  • the hydrogen storage material may be a compound which comprises hydrogen, i.e. a material in which hydrogen is stored chemically. Alternatively, it may be a material in which hydrogen is physically stored, for instance a solid onto which hydrogen is adsorbed or a liquid in which hydrogen is dissolved, and from which hydrogen can be released.
  • the hydrogen storage material may for instance comprise a chemical hydride, such as for instance a metal hydride; a chemical borohydride, for instance lithium borohydride; a protic solvent, for instance an alcohol such as isopropyl alcohol; a carbohydrate; a hydrocarbon; ammonia; an amine borane complex; formic acid; an imidazolium ionic liquid;
  • Such hydrogen storage materials are known in the art.
  • the hydrogen used in the process of the invention for producing a monohydric alcohol is molecular hydrogen. Typically, it is hydrogen gas.
  • the step of treating said polyhydric alcohol with hydrogen usually comprises treating said polyhydric alcohol with 3 ⁇ 4.
  • the step of treating said polyhydric alcohol with hydrogen usually comprises treating said polyhydric alcohol with hydrogen gas.
  • the process of the invention for producing a monohydric alcohol comprises treating said polyhydric alcohol with hydrogen gas.
  • the step of treating said polyhydric alcohol with hydrogen is carried out at a temperature of at least 50 °C.
  • the hydrogenolysis reaction is typically however carried out at relatively mild temperatures and pressures.
  • the step of treating the polyhydric alcohol with hydrogen is typically performed at a temperature of 250 °C (523 K) or less than 250 °C (473 K), and more typically at a temperature of 220 °C or less. In one embodiment, the step of treating the polyhydric alcohol with hydrogen is carried out at a temperature of 200 °C or less.
  • the step of treating the polyhydric alcohol with hydrogen is carried out at a temperature of from 50 °C to 250 °C, or for instance from 100 °C to 250 °C, from 100 °C to 220 °C, or for example from 150 °C to 200 °C.
  • the hydrogen pressure was found typically to affect the selectivity of the hydrogenolysis reaction for methanol, and was found to affect the conversion of the polyhydric alcohol to methanol.
  • the step of treating the polyhydric alcohol with hydrogen is usually performed at a hydrogen pressure of at least 1 bar, typically at least 12 bar, more typically at a hydrogen pressure of at least 15 bar, and even more typically at a hydrogen pressure of at least 18 bar.
  • the hydrogen pressure employed is from 1 bar to 250 bar, more typically from 12 bar to 250 bar, and even more typically from 15 bar to 250 bar, for instance from 18 bar to 250 bar. In one embodiment, the hydrogen pressure employed is about 20 bar.
  • the process of the invention may be carried out as continuous process or a batch process.
  • the process is a continuous process in which hydrogen is cofed in a recycled catalyst bed, either in the presence or absence of a solvent.
  • the step of treating the polyhydric alcohol with hydrogen is usually performed for longer than 5 hours, and more typically for at least 10 hours, in order to ensure that a relatively high percent conversion of the reactant is achieved. Even more typically, the reaction time is at least 15 hours, for instance for about 15 hours or for about 24 hours. In some embodiments, the step of treating the polyhydric alcohol with hydrogen is performed for longer than 24 hours, for instance for at least 72 hours. As shown in Fig. 5, the selectivity for methanol and ethanol was found to increase when the catalyst was used for such longer durations.
  • the monohydric alcohol produced by the process of the invention is recovered from the reaction mixture.
  • the reaction mixture comprises the monohydric alcohol product, the catalyst and, when the reaction is carried out in the presence of a solvent, the solvent.
  • the reaction mixture usually also comprises unreacted starting material, i.e. unreacted polyhydric alcohol.
  • the reaction mixture may also contain by-products (i.e. reaction products other than the monohydric alcohol of interest, which may for instance include other monohydric alcohols and other polyhydric alcohols) and/or impurities.
  • the step of recovering the monohydric alcohol from the reaction mixture typically involves separation of the monohydric alcohol from the catalyst, from any unreacted starting material and, when solvent is present, from the solvent.
  • the monohydric alcohol is also separated from that by-product or impurity.
  • the process of the invention further comprises the step of recovering said monohydric alcohol.
  • the monohydric alcohol produced by the process of the invention may be used as a fuel, typically an automotive fuel, or as a building block, reactant or feedstock in the production of other chemicals.
  • the monohydric alcohol may for instance be used to esterify unwanted free fatty acids present in the production of biodiesel.
  • the process of the invention can be used to convert the glycerol by-product of a biodiesel production process into methanol and/or ethanol, and that methanol and/or ethanol can in turn be used to esterify free fatty acids present in the biodiesel production process in order to produce further biodiesel.
  • the process of the invention further comprises esterifying a fatty acid with the monohydric alcohol thus produced.
  • the fatty acid is from a biodiesel production process and the esterification of the fatty acid with the monohydric alcohol produces further biodiesel.
  • the monohydric alcohol is methanol or ethanol and the compound which is converted to the monohydric alcohol in the first place is glycerol, which glycerol is a by-product of the same biodiesel production process.
  • the invention further provides a catalyst which comprises (a) iron oxide and (b) nanoparticles which comprise palladium.
  • the iron oxide in the catalyst of the invention can act as a support material.
  • the nanoparticles which comprise said palladium are supported on the iron oxide.
  • the palladium nanoparticles are typically present on the surface of the iron oxide.
  • the palladium in the nanoparticles of the catalyst of the invention is predominantly in metallic form, i.e. in the oxidation state 0.
  • the nanoparticles comprise said palladium in the oxidation state 0.
  • the nanoparticles may however further comprise palladium in an oxidation state other than 0, for instance in an oxidation state greater than 0, for instance an oxidation state of from +1 to +4.
  • Oxidation states greater than 0 for palladium include for instance +1, +2 and +4.
  • the nanoparticles consist of said palladium.
  • the catalyst of the invention may for instance comprise nanoparticles which consist of palladium, and nanoparticles which comprise iron and palladium.
  • all, or substantially all, of the nanoparticles further comprise iron.
  • the nanoparticles which further comprise iron may for instance consist of palladium and iron.
  • the iron present in the nanoparticles may be present in the nanoparticles in metallic form, i.e. in the oxidation state 0.
  • the iron present in the nanoparticles is usually present in the form of an alloy with the palladium.
  • said nanoparticles which further comprise iron comprise an alloy of palladium and iron.
  • some or all of said nanoparticles comprise an alloy of palladium and iron. In one embodiment, only some of the nanoparticles comprise an alloy of palladium and iron.
  • the catalyst may comprise nanoparticles which consist of palladium, and nanoparticles which comprise an alloy of palladium and iron. In another embodiment, all, or substantially all, of the nanoparticles comprise an alloy of palladium and iron.
  • the nanoparticles which comprise an alloy of palladium and iron may in some embodiments consist only of said alloy of palladium and iron.
  • nanoparticles which further comprise iron are typically bimetallic
  • the nanoparticles in the catalyst of the invention are bimetallic nanoparticles which comprise (i) said palladium, and (ii) iron.
  • the mean particle size of the nanoparticles in the catalyst of the invention is less than 50 nm. Usually for instance, the mean particle size of the nanoparticles in the catalyst of the invention is less than 20 nm. Even more typically, the mean particle size is less than 10 nm.
  • the mean particle size of the nanoparticles in the catalyst of the invention may be within the range of from 1 nm to 20 nm, or for instance within the range of from 1 nm to 10 nm. It could for instance be from 1 nm to 7 nm. In some embodiments, however, the mean particle size of the nanoparticles is equal to or less than 1 nm.
  • the particle size distribution of the nanoparticles in the catalyst of the invention is such that at least 90 % of the nanoparticles have a particle size of less than 20 nm. More typically, at least 90 % of the nanoparticles have a particle size of less than 10 nm, or for instance less than 7 nm.
  • the mean particle size of the nanoparticles in the catalyst of the invention is less than 5 nm.
  • the mean particle size of said nanoparticles may for instance be less than 3 nm, or for instance less than 1 nm.
  • the mean particle size of the nanoparticles in the catalyst of the invention may for instance be from 1 nm to 5 nm, or for instance from 1 nm to 3 nm. In a particularly preferred embodiment, the mean particle size of the nanoparticles in the catalyst of the invention is from 1.0 nm to 2.5 nm. For instance, the mean particle size of said nanoparticles may be about 1.5 nm.
  • the particle size distribution of the nanoparticles in the catalyst of the invention is such that at least 90 % of the nanoparticles have a particle size of less than 5 nm.
  • the particle size distribution of said nanoparticles may be such that at least 90 % of the nanoparticles have a particle size of less than 3.5 nm. Such a distribution is shown in Fig. 7.
  • the particle size distribution of said nanoparticles may be such that at least 90 % of the nanoparticles have a particle size of equal to or less than 1 nm.
  • the mean particle size of said nanoparticles is less than 3 nm and the particle size distribution of said nanoparticles is such that at least 90 % of the nanoparticles have a particle size of less than 5 nm.
  • the mean particle size of said nanoparticles may be less than 3 nm and the particle size distribution of said nanoparticles may be such that at least 90 % of the nanoparticles have a particle size of less than 3.5 nm.
  • the catalyst of the invention may further comprise palladium in the form of individual palladium atoms.
  • the individual palladium atoms are on the surface of the iron oxide.
  • the catalyst of the invention may comprise palladium both in the form of said nanoparticles which comprise palladium, and in the form of single palladium atoms dispersed on the iron oxide surface.
  • the mean particle size of said nanoparticles which comprise palladium is less than 5 nm
  • the particle size distribution of said nanoparticles is such that at least 90 % of the nanoparticles have a particle size of less than 10 nm
  • the catalyst of the invention further comprises individual atoms of palladium dispersed on the surface of the iron oxide.
  • the mean particle size of said nanoparticles which comprise palladium is less than 4 nm
  • the particle size distribution of said nanoparticles is such that at least 90 % of the nanoparticles have a particle size of less than 5 nm
  • the catalyst of the invention further comprises individual atoms of palladium dispersed on the surface of the iron oxide.
  • the mean particle size of the nanoparticles is less than 3 nm
  • the particle size distribution of said nanoparticles is such that at least 90 % of the nanoparticles have a particle size of less than 4 nm
  • the catalyst further comprises individual atoms of palladium dispersed on the surface of the iron oxide.
  • the mean particle size of the nanoparticles is in some embodiments less than or equal to 1 nm, and the particle size distribution of said nanoparticles may be such that at least 90 % of the nanoparticles have a particle size of less than 4 nm, and the catalyst further comprises individual atoms of palladium dispersed on the surface of the iron oxide.
  • the iron oxide in the catalyst of the invention comprises Fe 2 0 3 .
  • Fe 2 0 3 is typically formed during a calcination step in the preparation of the catalyst.
  • the iron oxide in the solid catalyst may further comprise other, more reduced forms of iron oxide, particularly if the catalyst has undergone a pre-reduction step during the preparation of the catalyst, or for instance if the catalyst has already been exposed to hydrogen in a hydrogenolysis process (such as the process of the invention for producing a monohydric alcohol by hydrogenolysis of a polyol).
  • the iron oxide in the catalyst of the invention typically comprises Fe 2 0 3 . It may however further comprise Fe 3 0 4 or FeO (which may be present due to partial reduction of Fe 2 0 3 ) or a mixture of Fe 3 0 4 and FeO, in addition to the Fe 2 0 3 .
  • the catalyst of the invention may further comprise Fe(0), i.e. iron metal.
  • Fe(0) i.e. iron metal.
  • Such Fe may for instance be present in the form of an alloy with palladium in the nanoparticles, as discussed hereinbefore.
  • iron metal may be present in the catalyst in the form of nanoparticles consisting only of iron metal.
  • the iron oxide in the catalyst of the invention has a surface which has undergone reduction.
  • Such surface reduction of iron oxide may for instance have occurred during a pre-reduction step during the preparation of the catalyst, or for instance if the catalyst has been already exposed to hydrogen in a hydrogenolysis process (such as the process of the invention for producing a monohydric alcohol). It is thought that the reduction of the surface of the iron oxide (with the palladium in close proximity) will cause the formation of nanoparticles comprising Fe and and palladium. These small but catalytically active nanoparticles are thought to offer much enhanced catalyst activity and selectivity due to electronic modification of band structure.
  • oxygen vacancies will be formed in the close vicinity of the Fe/Pd nanoparticles on the defective iron oxide surface due to the maintenance of electrical neutrality upon reduction.
  • the presence of oxygen vacancies may stabilize the clusters, and may further assist adsorption of the polyhydric alcohol molecule.
  • the iron oxide in the catalyst of the invention typically comprises oxygen vacancies.
  • the oxygen vacancies are at or near the surface of the iron oxide.
  • the palladium is present in the catalyst of the invention in an amount which is equal to or less than 50 weight %, based on the weight of the iron oxide. More typically, the palladium is present in an amount which is equal to or less than 30 weight %, based on the weight of the iron oxide. The palladium may for instance be present in an amount which is equal to or less than 20 weight %, or for instance which is equal to or less than 10 weight %, based on the weight of the iron oxide. In some embodiments, for instance, the palladium is present in an amount which is equal to or less than 8 weight %, based on the weight of the iron oxide.
  • the palladium is present in the catalyst of the invention in an amount of from 0.1 weight % to 50 weight %, based on the weight of the iron oxide. More typically, the palladium is present in an amount of from 0.5 weight % to 30 weight %, based on the weight of the iron oxide.
  • the palladium may for instance be present in an amount of from 1 weight % to 20 weight %, or for instance from 2 weight % to 10 weight %. In some embodiments, for instance, the palladium is present in an amount of from 2 weight % to 8 weight %, based on the weight of the iron oxide, for instance from 3 weight % to 7 weight %.
  • the iron oxide in the catalyst of the invention may be doped with a dopant element. It is a finding of the invention that doping the iron oxide support of the catalyst with a dopant element can lead to further improvements in the activity and/or selectivity of the catalyst, when used in the process of the invention.
  • the dopant element is a metal other than iron, for instance a transition metal other than iron.
  • the dopant element, when present, is present in the catalyst in addition to the palladium.
  • the dopant element, when present is typically other than palladium. (That is to say, the dopant is typically a metal other than iron and other than palladium.)
  • the dopant element may for instance be a first row transition metal other than iron.
  • the dopant element may be selected from Sc, Ti, V, Cr, Mn, Co, Ni and Cu.
  • the dopant is selected from Sc, Ti, V, Cr, Mn, Co and Cu. More typically, it is selected from V, Cr, Mn, Co and Cu.
  • the dopant element is cobalt (Co).
  • Such dopant elements, and especially cobalt may provide further improvements in the activity and selectivity of the catalyst.
  • the iron oxide in the catalyst of the invention may or may not be doped with a dopant element. When the iron oxide is doped with a dopant element, the dopant element is preferably cobalt.
  • the catalyst used in the process of the invention comprises (a) cobalt-doped iron oxide and (b) palladium.
  • the iron oxide may alternatively, of course, not be doped with a dopant element, i.e. the iron oxide may be undoped.
  • Catalysts in which the iron oxide is not doped with a dopant element i.e. in which the iron oxide is "undoped" are described in further detail hereinbelow, in the Example.
  • the invention further provides a catalyst of the invention as defined herein which is obtainable by a process of the invention as defined herein for producing such a catalyst.
  • the invention further provides the use of a catalyst as defined herein as a catalyst for the hydrogenolysis of a polyhydric alcohol.
  • the catalysts of the invention which comprise (a) iron oxide and (b) nanoparticles which comprise palladium, may be produced by the process of the invention for producing a catalyst, which process comprises:
  • a co-precipitation step comprising contacting (a) a solution, which solution comprises a palladium salt and an iron salt dissolved in a solvent, with (b) a base, to produce a precipitate which comprises one or more compounds comprising said iron and said palladium; (2) a separation step, comprising separating the precipitate from the solvent; and (3) a calcination step, comprising calcining the precipitate by heating the precipitate in air.
  • the process further comprises: (4) a reduction step, comprising heating the calcined precipitate in the presence of H 2 .
  • the percentage by weight of palladium in the catalyst can be accurately controlled by varying the proportions of the palladium and iron salts employed in the solution used in step (1).
  • any of the catalysts of the invention defined above, having any of the abovementioned percentages by weight of palladium based on the mass of iron oxide in the catalyst can be produced by dissolving the correct amounts of palladium and iron salts in the solution used in step (1).
  • the ratio of palladium to iron in said solution is selected to produce a catalyst wherein the palladium is present in an amount which is equal to or less than 50 weight %, based on the weight of the iron oxide. More typically, the ratio of palladium to iron in said solution is selected to produce a catalyst wherein the palladium is present in an amount which is equal to or less than 30 weight %, based on the weight of the iron oxide.
  • the ratio of palladium to iron in said solution may for instance be selected to produce a catalyst wherein the palladium is present in an amount which is equal to or less than 20 weight %, or for instance which is equal to or less than 10 weight %, based on the weight of the iron oxide. In some embodiments, for instance, the ratio of palladium to iron in said solution is selected to produce a catalyst wherein the palladium is present in an amount which is equal to or less than 8 weight %, based on the weight of the iron oxide.
  • the ratio of palladium to iron in said solution is selected to produce a catalyst wherein the palladium is present in the catalyst of the invention in an amount of from 0.1 weight % to 50 weight %, based on the weight of the iron oxide. More typically, the ratio of palladium to iron in said solution is selected to produce a catalyst in which the palladium is present in an amount of from 0.5 weight % to 30 weight %, based on the weight of the iron oxide.
  • the ratio of palladium to iron in said solution may for instance be selected to produce a catalyst wherein the palladium is present in an amount of from 1 weight % to 20 weight %, or for instance from 2 weight % to 10 weight %, based on the weight of the iron oxide.
  • the ratio of palladium to iron in said solution is selected to produce a catalyst wherein the palladium is present in an amount of from 2 weight % to 8 weight %, based on the weight of the iron oxide, or for instance from 3 weight % to 7 weight %.
  • the solvent used in the co-precipitation step comprises water.
  • the co-precipitation step (1) comprises contacting (a) a solution, which solution comprises a palladium salt and an iron salt dissolved in a solvent which comprises water, with (b) a base, to produce a precipitate which comprises one or more compounds comprising said iron and said palladium.
  • the palladium salt may be any suitable salt which is soluble in the solvent.
  • the solvent is typically water.
  • the palladium salt is a water soluble palladium salt. It is typically a water-soluble palladium (II) salt.
  • An example of a water soluble palladium salt is palladium nitrate.
  • the palladium salt may for instance be palladium nitrate.
  • the iron salt may be any suitable salt which is soluble in the solvent.
  • the solvent is typically water.
  • the iron salt is a water soluble iron salt. It is typically a water-soluble iron (III) salt.
  • An example of a water soluble iron salt is iron nitrate.
  • the iron salt may for instance be iron nitrate. Typically, it is iron (III) nitrate.
  • the co-precipitation step comprises contacting: (a) said solution, which is an aqueous solution, with (b) a second aqueous solution which comprises said base. The contacting may be performed whilst stirring.
  • any suitable base may be used in the process of the invention for producing a catalyst.
  • the base is a metal carbonate.
  • the metal carbonate is an alkali metal carbonate, for instance sodium carbonate.
  • the precipitate produced in step (1) generally comprises one or more hydroxide or oxide-hydroxide compounds comprising Pd and Fe.
  • the Pd atoms are usually atomically dispersed and bonded within a sol-gel like matrix, formed during the co-precipitation step, comprising an Fe-O-Fe network.
  • iron and palladium atoms are generally connected to one other via bridging oxygen atoms.
  • the precipitate produced in step (1) comprises a polymeric network comprising Pd atoms and Fe atoms bonded together via bridging oxygen atoms. A schematic representation of an example of such a network is shown in Fig. 1.
  • the precipitate produced in step (1) comprises one or more hydroxide or oxide-hydroxide compounds comprising said iron and said palladium.
  • the precipitate may for instance comprise a mixed hydroxide of iron and palladium, or a mixed oxide-hydroxide of iron and palladium.
  • the precipitate may comprise a mixture of palladium hydroxide and iron hydroxide, a mixture of palladium hydroxide and iron oxide-hydroxide, or any combination of these.
  • the precipitate produced in step (1) typically comprises one or more hydroxide or oxide-hydroxide compounds comprising said iron and said palladium.
  • the precipitate produced in step (1) may for instance comprise one or more hydroxide compounds comprising said iron and said palladium.
  • the precipitate produced in step (1) comprises a polymeric network comprising Pd atoms and Fe atoms bonded together via oxygen atoms.
  • the step of contacting said solution with said base comprises increasing the pH of the solution from a first pH to a second pH, wherein the second pH is greater than the first pH.
  • the second pH is at least 8.
  • the first pH is typically less than 8, for instance from 5 to 7.5, or for instance equal to or less than 7. More typically the second pH is at least 8.5, for instance at least 9.
  • the second pH is typically for instance from 8.0 to 12.0, for example from 8.5 to 10.0, for instance about 9.0.
  • the co-precipitation step (1) may further comprise an aging step.
  • the aging step may comprise allowing the precipitate to remain in contact with a solvent for a period of time.
  • the solvent is the solvent from which it was precipitated (usually water).
  • the period of time may for instance be at least 1 hour, for instance at least 5 hours, or for instance up to about 24 hours.
  • the aging step may or may not comprise heating the co- precipitate in the presence of said solvent.
  • the co-precipitate may be heated to a temperature of up to about 80 °C, or for instance up to about 90 °C, during said period of time.
  • the co-precipitate may be heated at the temperature for up to about 24 hours.
  • the aging step does not comprise heating.
  • any suitable means can be used to separate the precipitate from solution.
  • the separation may be performed by filtration or by
  • the separation step further comprises washing the precipitate, after separating the precipitate from solution.
  • the precipitate is washed with deionised water.
  • the separation step may additionally further comprise drying the precipitate.
  • the precipitate is typically dried at a temperature of equal to or greater than 70 °C, e.g. at a temperature of from 80 to 120 °C. It is typically dried at the temperature for a number of hours, e.g. for 4 hours or more. It is typically dried at the temperature for 8 to 16 hours.
  • the precipitate is usually dried in air.
  • the calcination step (3) typically comprises heating the precipitate in air to a temperature of at least 200 °C. More typically, the precipitate is heated in air to a temperature of at least 250 °C, or for instance to a temperature of at least 280 °C. Usually, the precipitate is heated in air to a temperature of about 300 °C.
  • the precipitate is heated in air at the temperature for at least 1 hour, more typically for at least 1.5 hours, for instance for about 2 hours.
  • the co-precipitate is typically heated to the temperature in static air.
  • the reduction step (4) comprises heating the calcined precipitate in the presence of H 2 .
  • the reduction step comprises heating the calcined precipitate in the presence of a mixture of H 2 and an inert gas, such as N 2 , and more typically under a flowing stream of H 2 and the inert gas.
  • the calcined product is typically heated in the presence of said H 2 for at least 1 hour.
  • the calcined precipitate may be heated in the presence of said 3 ⁇ 4 to a temperature of at least 120 °C. More typically, the reduction step (4) comprises heating the calcined product in the presence of said 3 ⁇ 4 to a temperature of at least 150 °C, or, for instance, to a temperature of at least 170 °C.
  • the calcined product is typically heated in the presence of said H 2 at said temperature for at least 1 hour.
  • the catalyst produced by the process of the invention for producing a catalyst which comprises (a) iron oxide and (b) nanoparticles which comprise palladium, may be as further defined herein for the catalyst of the invention.
  • the process of the invention for producing a catalyst typically further comprises recovering the catalyst.
  • the process further comprises: using the catalyst thus produced as a catalyst for the hydrogenolysis of a polyhydric alcohol.
  • the process of the invention for producing a catalyst which comprises (a) iron oxide and (b) nanoparticles which comprise palladium may further comprise: producing a monohydric alcohol, by treating a polyhydric alcohol with hydrogen in the presence of said catalyst.
  • the step of treating said polyhydric alcohol with hydrogen in the presence of said catalyst is as further defined herein for the process of the invention for producing a monohydric alcohol.
  • the invention further provides a catalyst which is obtainable by a process of the invention as defined above, for producing a catalyst which comprises (a) iron oxide and (b) nanoparticles which comprise palladium. Further provided is the use of such a catalyst for the hydrogenolysis of a polyhydric alcohol.
  • ethylene glycol the simplest representative of biomass-derived polyols
  • ethylene glycol is converted directly to the lower alcohols, by hydrogenolysis, with high selectivities (>80%) using a noble-metal / Fe 2 0 3 catalyst.
  • This opens up an exciting new catalytic process namely a non-enzymatic bio-alcohol production process which depends on concerted C-C or C-0 bond breakage and C-H bond formation.
  • a unique metal-support interaction within the carefully prepared co-precipitated catalyst, is revealed to give a supported metal phase of extremely high dispersion ranging from small nanoparticle clusters down to individual metal atoms, on defective iron oxide. This is thought to be responsible for highly cooperative catalysis.
  • a typical synthesis for preparing 1 g of 5 wt% Pd/Fe 2 0 3 catalyst i.e. Pd/Fe 2 0 3 containing 5 weight % Pd, based on the mass of the iron oxide
  • Pd/Fe 2 0 3 containing 5 weight % Pd, based on the mass of the iron oxide was as follows: 0.3309 g of palladium nitrate (containing 15.1 lwt% Pd) and 5.071 g of Fe(N0 3 ) 3 .9H 2 0 were dissolved in a 200 mL water at room temperature under stirring. Then, 1.0 M Na 2 C0 3 solution was added dropwise to the mixed solution until the pH of the final solution reached ca. 9.0.
  • Catalyst testing hydrogenolysis of ethylene glycol in a liquid phase batch reactor
  • the hydrogenolysis reaction was carried out in liquid phase using a 160 mL autoclave high pressure reactor.
  • 30 mL of ethylene glycol solution (0.85 mol/L) and 0.50 g of catalyst were loaded in a glove box.
  • the reactor was flushed with pure hydrogen to remove any traces of oxygen.
  • the autoclave was pressurized to 20 bars of hydrogen at room temperature. Then, it was heated up to 195°C and allowed to react for 24 hours with constant stirring
  • the autoclave was then cooled down to -60 °C by dry ice / acetone bath.
  • the gas phase was analysed by a Perkin Elmer Autosystem XL Arnel Gas phase GC- FID-Methanator in order to determinate the concentrations of CO, CH 4 and C0 2 after the reaction.
  • the liquid phase was analysed by a Perkin Elmer 200 series HPLC equipped with a refractive index detector where a 0.60 mL of 58 mmol/L sucrose solution was added as an external standard to determinate the concentration of ethylene glycol, methanol and ethanol after the reaction. The mass balance of this typical catalytic batch reaction of over 95% was ensured.
  • Catalysts containing 5 wt% Pd (based on the weight of the metal oxide) on various metal oxides (Fe 2 0 3 , ZnO, Ga 2 0 3 , Ce0 2 and A1 2 0 3 ) were prepared by a co-precipitation technique as described above, where 1.0 M Na 2 C0 3 solution was added dropwise to a mixed solution of the metal nitrates until the pH of the final solution reached ca. 9.0. Each sample was aged, dried and calcined in an identical manner. The samples were tested in ethylene glycol solution after a pre-reduction stage with hydrogen at 200°C for 1 h.
  • Figure 4 shows a further improvement in accumulative selectivity of over 50% after the catalyst was tested for 72h.
  • Time fraction analysis in Fig. 5 clearly suggests the catalyst initially gave higher ethylene glycol conversions but mainly producing C0 2 . This could be due to the aqueous reforming reaction of ethylene glycol to carbon dioxide and hydrogen (C 2 H 6 02 + 2H 2 0 ⁇ 2C0 2 + 5H 2 ) which is known to take place near our reaction temperature (R. D. Cortright, R. R. Davda, J. A. Dumesic, Nature 418, 964 (2002); J. W. Shabaker, G. W. Huber, R. R. Davda, R. D. Cortright, J. A.
  • ethylene glycol may act as a reductant for iron oxide (3C 2 H 6 0 2 + 5Fe 2 0 3 ⁇ 6C0 2 + 9H 2 0 + 1 OFe) in the presence of Pd. That the latter reaction has probably played an important part for the initial production of C0 2 .
  • selectivity for the alcohols was increased accordingly. After this induction, the catalyst gave much higher selectivity towards the alcohols. At least 80% selectivity (with methanol selectivity >50%) towards the lower alcohols (methanol and ethanol) was obtained at about 4.3% conversion between the period of 24 to 72 h.
  • a scanning transmission electron microscopy high angle annular dark field (STEM- HAADF) image of the sample after pre-reduction was taken using a JOEL 3000F electron microscope with both high-resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy (STEM) modes.
  • the image showed a large number of very small metal particles of high contrast in a number of thin areas, i.e. at the edge surfaces of the iron oxide support).
  • the particles are around ca.1.0-2.5 nm in diameter with 1.5 nm being the most probable particle size.
  • Using aberration corrected 2200MCO - HAADF STEM microscopy to focus on a thin area of iron oxide support near the edge confirmed the dense array of small metal particles.
  • the particle size distribution of the metal nanoparticles is shown in Fig. 7. Higher magnifications clearly showed the presence of even smaller metal clusters (many of them below 1.0 nm) with occasionally single atoms found on support surface. This result is very surprising with particular regards to the small metal sizes and their stability on surface since the sample had experienced various heat treatments. EDX analysis suggested that the surface clusters contained Pd and possibly Fe but it was unable to ascertain this measurement in the background of bulk iron oxide.
  • Fig. 8 shows XRD patterns of the pre-reduced Pd/Fe 2 0 3 (lh), which gives a characteristic Fe 2 0 3 phase but with no Pd peak observed, indicative of extremely small Pd particles on the iron oxide surface.
  • two additional broad diffraction peaks marginally differentiable from the background, as shown at 40.76 and 47.09 (2 ⁇ degree) were observed after the sample was tested for this reaction at prolonged time (a small degree of sintering).
  • the diffraction peaks of Pd (1 1 1) and Pd (2 0 0) are at 40.01 and 46.54 (2 ⁇ degree) and PdFe (1 1 1) and FePd (2 0 0) peaks at 40.79 and 47.27 (2 ⁇ degree), respectively.
  • the positions of the two peaks matched more closely with those of PdFe than Pd.
  • XRD peaks of our previously synthesized PdFe nanoparticles ca. 4.6 nm
  • a polyol process C. H. Yu, C. C. H. Lo, K. Tarn, S. C. Tsang, J Phys Chem C 11 1, 7879, 2007
  • thermodynamic driving force for this reaction Fig. 12 clearly shows the absence of typical hydrogen evolution peak of ⁇ -Pd-H (C. W. A. Chan, Y. Xie, N. Cailuo, K. M. K. Yu, J. Cookson, P. Bishop, S. C. Tsang, Chem. Commun. 47, 7971, 2011) as compared to alumina supported Pd at around 70°C (negative peak) in the second TPR profile, the fact is consistent with the formation of highly dispersive Pd atoms and PdFe clusters.
  • the linearity for the In k vs 1/T plot (Fig. 15) gave a slope of -Ea/R.
  • the apparent activation energy for methanol production was determined to be 96 kJmol "1 .
  • the stable -Fe-O-Fe- rich area will constituent to the bulk support where the reduced metal atoms and clusters may still be partially connected to the iron oxide support to offer the kinetic stability against sintering after the heat treatments.
  • the co-reduction of a small surface -Fe-O- network with Pd at close proximity will give PdFe clusters.
  • These small but catalytically active PdFe clusters are thought to offer much enhanced catalyst activity and selectivity due to electronic modification of band structure.
  • oxygen vacancies will be formed in close vicinity to the PdFe clusters on the defective surface due to the maintenance of electrical neutrality upon reduction (their presence may stabilize the clusters), which may further assist adsorption of the ethylene glycol molecule (T. L.

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Abstract

Cette invention concerne un procédé de production d'un alcool monohydroxylé par hydrogénolyse d'un polyol, ledit procédé consistant à traiter un polyol avec de l'hydrogène en présence d'un catalyseur solide qui comprend (a) de l'oxyde de fer et (b) un métal qui est un métal noble ou du nickel. Cette invention concerne en outre un catalyseur, qui comprend de l'oxyde de fer et des nanoparticules qui comprennent du palladium. Un procédé de production du catalyseur est également décrit, ledit procédé comprenant : (1) une étape de co-précipitation consistant à mettre en contact (a) une solution, qui comprend un sel de palladium et un sel de fer dissous dans un solvant, avec (b) une base, pour former un précipité qui comprend un ou plusieurs composés dont ledit fer et ledit palladium; (2) une étape de séparation, consistant à séparer le précipité du solvant; et (3) une étape de calcination, consistant à calciner le précipité par chauffage du précipité dans l'air. L'utilisation du catalyseur selon l'invention pout l'hydrogénolyse d'un polyol est également décrite.
PCT/GB2013/050881 2012-04-04 2013-04-04 Procédé de production d'alcool WO2013150305A2 (fr)

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CN103922893A (zh) * 2014-04-19 2014-07-16 青岛科技大学 一种复合催化剂催化甘油氢解制备1,2-丙二醇的方法
CN104086369A (zh) * 2014-06-18 2014-10-08 华南理工大学 木薯渣氢解制备低级醇的方法
CN104492436A (zh) * 2014-12-12 2015-04-08 中国科学院西双版纳热带植物园 一种碳基磁性固体碱催化剂及其应用
WO2017063558A1 (fr) * 2015-10-13 2017-04-20 吴倍任 Matériau composite dans une hydrogénolyse catalytique, son procédé de préparation et son utilisation
CN106902842A (zh) * 2017-03-20 2017-06-30 北京工业大学 一种以MOFs衍生碳基材料为载体的负载型钯催化剂的制备及应用
EP3375905A1 (fr) * 2017-03-16 2018-09-19 Kabushiki Kaisha Toshiba Système de réaction chimique
CN108579810A (zh) * 2018-03-12 2018-09-28 北京科技大学 一种合成贵金属MOFs复合材料的方法
CN109304213A (zh) * 2017-07-28 2019-02-05 中国科学院宁波材料技术与工程研究所 一种加氢裂化催化剂及其制备方法与应用

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CN107490610B (zh) * 2017-09-05 2019-09-27 济南大学 一种手性mof-石墨烯杂化材料及其制备方法和应用

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CN103922893A (zh) * 2014-04-19 2014-07-16 青岛科技大学 一种复合催化剂催化甘油氢解制备1,2-丙二醇的方法
CN103922893B (zh) * 2014-04-19 2015-11-25 青岛科技大学 一种复合催化剂催化甘油氢解制备1,2-丙二醇的方法
CN104086369A (zh) * 2014-06-18 2014-10-08 华南理工大学 木薯渣氢解制备低级醇的方法
CN104492436A (zh) * 2014-12-12 2015-04-08 中国科学院西双版纳热带植物园 一种碳基磁性固体碱催化剂及其应用
CN104492436B (zh) * 2014-12-12 2016-09-07 中国科学院西双版纳热带植物园 一种碳基磁性固体碱催化剂及其应用
WO2017063558A1 (fr) * 2015-10-13 2017-04-20 吴倍任 Matériau composite dans une hydrogénolyse catalytique, son procédé de préparation et son utilisation
EP3375905A1 (fr) * 2017-03-16 2018-09-19 Kabushiki Kaisha Toshiba Système de réaction chimique
CN106902842A (zh) * 2017-03-20 2017-06-30 北京工业大学 一种以MOFs衍生碳基材料为载体的负载型钯催化剂的制备及应用
CN109304213A (zh) * 2017-07-28 2019-02-05 中国科学院宁波材料技术与工程研究所 一种加氢裂化催化剂及其制备方法与应用
CN108579810A (zh) * 2018-03-12 2018-09-28 北京科技大学 一种合成贵金属MOFs复合材料的方法
CN108579810B (zh) * 2018-03-12 2020-09-11 北京科技大学 一种合成贵金属MOFs复合材料的方法

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