The invention relates to a method for preparing a chemical compound from a starting compound using a ruthenium metal catalyst on a zirconium oxide support. The invention also relates to a ruthenium metal catalyst on a zirconium oxide support suitable for use in said chemical reaction.

The demand for chemicals, materials and fuels around the world is ever increasing, which in turn has placed greater pressure upon the fossil reserves from which they are derived and the environmental problems associated with their exploitation. Ultimately, the exhaustion of these reserves will force a switch to more renewable sources, such as those obtained from lignocellulosic biomass. Consequently, much effort has been made to develop methodologies of utilizing biomass such that the energy demand is minimal and close to being carbon neutral.

As in the petrochemical industry, a number of promising biomass- derived platform molecules (also known as building blocks) have been identified. Such platform molecules include acids (e.g. levulinic acid (LA) and lactic acid), furans (e.g. furfural, hydroxymethylfurfural (HMF), and alkoxymethylfurfurals (e.g. methoxymethylfurfural (MMF))), saccharides (e.g. glucose, fructose, xylose and galactose), polyols (e.g. glycerol, sorbitol and xylitol), and monoalcohols (e.g. ethanol). These molecules can be converted by a catalytic reaction, such as a reduction or an oxidation reaction, into other valuable products which can be used as renewable chemicals, additives, solvents and liquid fuels.

In particular, LA can be converted via catalytic reactions, such as a hydrogenation or deoxygenation reaction, into another valuable chemicals, such as gamma-valerolactone (GVL), methyltetrahydrofuran (MTHF), pentanoic acid (PA), pentanediol (PD), ethyl levulinate (EL) or a pentanoic acid ester (PE).

Glycerol can be converted via catalytic reactions, such as a oxidation or hydrogenolysis reaction, into another valuable chemical, such as glyceric acid, 1,3-propanediol, propylene glycol, lactic acid. Sorbitol can be converted via catalytic reactions, such as hydrogenolysis, into another valuable chemical, such as propylene glycol, 1,3-propanediol, ethylene glycol, and glycerol. Xylitol can be converted via catalytic reactions, such as hydrogenolysis, into another valuable chemical, such as propylene glycol, ethylene glycol and glycerol.

HMF can be converted via catalytic reactions, such as a hydrogenation, hydrogenolysis, oxidation or reduction reaction, into another valuable chemical, such as 2,5-dimethylfuran (DMF), 2,5-furandicarboxylic acid (2,5-FDCA) and its dimethyl ester (DMFD), 2,5-bis(hydroxymethyl) furan (2,5-BHMF) and 2,5-bis(hydroxymethyl) tetrahydrofuran (2,5- BHTHF).

Saccharides, in particular sugars (i.e. monosaccharides and disaccharides), as well as oligosaccharides and polysaccharides (e.g.

cellulose), preferably derived from lignocellulose biomass, can be converted via catalytic reactions, such as a hydrogenation or oxidation reaction, into another valuable chemical, such as their corresponding polyols (also known as "sugar alcohols") and their corresponding carboxylic acids (also known as "sugar acids"). Sugar acids typically include aldonic acids, ulosonic acids uronic acids and aldaric acids.

Various catalysts have been evaluated for their use in the conversion of biomass- derived platform chemicals including supported noble metal and base metal catalysts (Besson, M. et al. Chem. Rev. 3 (2014) 1827- 1870; and Alonso, D.M. et al. Green Chem. 12 (2010) 1493-1513). Supported ruthenium based catalysts, in particular catalyst comprising ruthenium on a carbon support (Ru/C), have been reported as one of the most used and most effective catalysts for a number of catalytic reactions, such as hydrogenation and hydrogenolysis reactions.

For the hydrogenation of LA into GVL in the presence of either hydrogen or a liquid hydrogen donor, near quantitative yields are obtained (Wright, W.R.H. et al. ChemSusChem 5 (2012) 1657-1667). Ruthenium metal on a carbon support catalyst has also been used for the production of dimethylfuran via the hydrogenation of HMF in the presence of a hydrogen donor in a one step process with high yields (Jae, J. et al. ChemSusChem 6 (2013) 1158-1162; Jae, J. et al. ChemCatChem 6 (2014) 848-856; and, Hu„ L. et al. Ind. Eng. Chem. Res. 53 (2014) 3056-3064). Hydrogenation of sugars, such as glucose, glyceraldehyde, maltose and galactose, to their corresponding polyols has also been shown to be efficient and highly selective when using a ruthenium on a carbon support catalyst (Sifontes Herrera, V.A. J. Chem. Technol. Biotechnol. 86 (2011) 658-668; and, Aho, A. et al. Catal. Sci. Technol. 5 (2015) 953-959). For the hydrogenolysis of glycerol, the use of carbon- supported Ru based catalysts has been reported in the literature (Maris, E. et al. J. Catal. 249 (2007) 328-337).

A drawback of this type of catalyst which has been reported in the literature is its instability, with deactivation being observed in certain solvents upon recycling (Wettstein, S.G. et al. Appl. Catal. B 117 (2012) 321- 329; and, Yan, Z. et al. Energy Fuels 23 (2009) 3853-3858). Carbon supports are also known to not be suitable for certain industrial use, due to them not being resistant to the multiple thermal treatments that are required for catalyst regeneration by coke-burn off.

Furthermore, the Ru/C catalyst has been reported in the literature to perform poorly in the presence of non-pure feedstocks of biomass derived platform chemicals. In particular, LA feedstocks containing some traces of the contaminant sulfuric acid (e.g. 0.1 wt.%) result in the Ru/C catalyst being poisoned which leads to poor activity and selectivity to the desired products of EL or GVL (Pan, T. et al. Green Chem. 15 (2013) 2967-2974; and Heeres, H. et al. Green Chem. 11 (2009) 1247-1255).

Supported ruthenium catalysts, in general, have been described as being poorly compatible with sulfuric acid, with ruthenium on a titanium oxide support catalyst also being reported as another example of a supported ruthenium catalyst which performs poorly in the presence of sulfuric acid (H2SO4) (Alonso, D.M. et al. Green Chem. 12 (2010) 1493-1513, Pan, T. et al. Green Chem. 15 (2013) 2967-2974; and Heeres, H. et al. Green Chem. 11 (2009) 1247-1255). These trace amounts of sulfuric acid are typically carried over from the previous step of biomass conversion, in which cellulose is hydrolyzed by acid catalysis step by H2SO4 or sugars which are converted to LA and alkoxymethylfurfurals in an acid-catalyzed reaction, and can lead to problems further downstream in the production process.

In the last few years, a large variety of catalysts have been developed in order to obtain high GVL yields starting from pure LA feedstocks. Heterogeneous ruthenium catalysts based on different supports have been reported to perform the best, with Ru/C and Ru/TiC typically giving the highest activities (Wright, W.R.H. et al. ChemSusChem 5 (2012) 1657-1667). Other metallic active phases, including bimetallic alloys, have also been developed for this reaction, also with good yields being reported (Lange, J.-P., et al. Angew. Chem. Int. Ed. 49 (2010) 4479-4483). Catalyst stability, both upon long term use or extensive recycling as well as in the presence of contaminants that can be present in the LA feedstocks, is much less studied and often not commented on. For those limited studies in which catalyst stability is commented on, deactivation is commonly observed.

Moreover, the few examples in the open literature that report on the effect of contaminants on catalytic performance in the LA-to-GVL reaction show a large drop in activity in the presence of non-pure LA feedstocks containing traces of sulfuric acid (Braden, D.J. et al. Green Chem. 13 (2011) 1755- 1765). In an industrial process, any catalyst used will nonetheless encounter non-pure LA feedstocks, with typical traces of contaminants (e.g. mineral acids (e.g. H2SO4, H3PO4, HBr, HNO3, HCIO4 and HC1), halide compounds, phenolics, lignins, furans, small organic acids (i.e. C1-C2 organic acids) and humins and combinations thereof being present as a result of the hydrolysis process used to produce the LA feedstocks.

Accordingly, there remains a need for a catalyst useful in catalyzing the conversion of a starting compound, in particular a starting compound selected from the group consisting of a levulinic acid source, saccharides, furans and alcohols, and more in particular a levulinic acid source, into another useful chemical compound as mentioned herein-above, in particular a catalyst that is advantageous in one or more of the following aspects: catalytic activity, catalytic selectivity towards a specific useful compound of interest, catalytic productivity, and robustness under reaction conditions (resistant to sintering or poisoning).

In particular the inventors have surprisingly found that a specific group of catalysts display a satisfactory activity, selectivity, productivity and/or robustness for a prolonged period of time in a method for converting a biomass- derived platform chemical, such as LA, into another useful compound, such as GVL. More in particular the inventors found that such catalysts are preparable by a specific method.

Accordingly, the invention relates to a method for preparing a chemical compound from a starting compound in a contaminant containing feedstock comprising the steps of contacting the contaminant containing feedstock with a metal catalyst on a support, and preparing a chemical compound by a chemical reaction, wherein the feedstock comprises a contaminant in the amount of at least 0.01 wt. %, based on the weight of the feedstock, wherein the contaminant is selected from the group consisting of sulfur compounds, halide salts, mineral acids and salts thereof, phenolics, lignins, furans, small organic acids (i.e. C1-C2 organic acids), humins, and combinations thereof, and preferably comprises a sulfur compound or humin, wherein the starting compound is subjected to a chemical reaction catalyzed by a metal catalyst on a support in the presence of the

contaminant as defined herein, wherein the metal comprises ruthenium and wherein the support comprises zirconium oxide.

Further, the invention relates to a method for the production of a fuel component or a monomer or a solvent comprising the steps of forming gamma-valerolactone according to the method of the invention, and converting gamma-valerolactone into a fuel component; a monomer or a solvent. In case of the production of a monomer, the monomer preferably is a monomer for the production of a polyamide or a polyester.

Further, the invention relates to a ruthenium catalyst on a zirconium oxide support, wherein the catalyst is obtainable by a metal-ion impregnation method.

In a further preferred aspect, the invention relates to a metal catalyst on a zirconium oxide support, wherein metal comprises ruthenium and optionally one or more other metals, wherein the metal on the support is present on the support in the form of metal atoms (monoatomic) and/or nanoparticles, wherein said catalyst comprises metal in an amount of in the range of 0.1-20 wt.%, based on the weight of the catalyst, wherein said catalyst has an average pore diameter in the range of 0.5-100 nm and a total pore volume of at least 0.1 cm ³ /g.

As illustrated in the Examples, using a ruthenium metal catalyst on a zirconium oxide support in the method of the invention is particularly advantageous in that it results in a more robust method under reaction conditions with an improved resistance to poisoning when converting a starting compound, such as the biomass-derived platform molecules described hereinabove, to a specific useful chemical compound of interest, especially GVL.

The method of the invention is in particular advantageous in that it allows for the conversion of a starting compound, in particular when the starting compound is a feedstock, preferably a levulinic acid source (LA source), to a desired product, in particular GVL, in the presence of a contaminant, such as sulfuric acid, in an amount of 0.01 wt. % or more, based on the weight of the feedstock, without (significant) deactivation of the catalyst or at least with greatly reduced deactivation compared to e.g. a Ru catalyst on carbon (as commercially available from Sigma- Aldrich).

Without wishing to be bound to any theory, it is believed that the catalyst of the invention acts as a contaminant (such as sulphates and phosphates), , sequestering (scavenging) sorbent.

Figure 1 shows the production of GVL (black column) during the hydrogenation of a LA feedstock in the presence of H2SO4 in an amount in the range of 0.1-1 wt.%, based on the weight of the feedstock, the LA conversion (grey square) and the Zr/S molar ratio (dark grey diamond), using a monometallic 1 wt.% Ru/Zr02 catalyst made with a metal ion impregnation method.

Figure 2 shows the production of GVL (black column) during the hydrogenation of a LA feedstock in the presence of H2SO4 in an amount in the range of 0-0.1 wt.%, based on the weight of the feedstock, the LA conversion (grey square) and the Ru/S molar ratio (dark grey diamond), using a monometallic 5 wt.% Ru/C reference catalyst (Sigma-Aldrich).

Figures 3 shows the production of GVL during the hydrogenation of a LA feedstock in the presence of H2SO4 in an amount of 0.1 wt.%, based on the weight of the feedstock, using a 5 wt.% Ru/C reference catalyst (Sigma-Aldrich), a 1 wt.% Ru/Zr02 catalyst and 5 wt.% Ru and 10 wt.% of Mo and Re, respectively, of the bimetallic Ru,Mo/C and Ru,Re/C reference catalysts.

Figure 4 shows the production of GVL during the hydrogenation of a LA feedstock in the presence of H2SO4 in an amount of 0.1 wt.%, based on the weight of the feedstock, using a 0.5 wt.% and a 1 wt.% Ru/Zr02 catalyst. Figure 5 shows the production of GVL during the hydrogenation of a LA feedstock in the presence of no impurity, H2SO4 in an amount of 0.1 wt.%, H2SO4 in an amount of 0.5 wt.%, Na2S0 ₄ in an amount of 0.7 wt.%, and Na2S04 H2S0 ₄ in an amount of 0.7 wt.%/0.1 wt.%, based on the weight of the feedstock, using a 1 wt.% Ru/Zr02 catalyst at time intervals of 30 min (dark column), 1 h (dark grey column), 2 h (medium grey column), and 3 h (light grey column).

Figure 6 shows the production of GVL during the hydrogenation of a LA feedstock in the presence of no impurity, HC1 in an amount of 0.5 wt.%, HC1 in an amount of 0.1 wt.%, HC1 in an amount of 0.05 wt.%, NaCl in an amount of 0.5 wt.%, and H3PC in an amount of 0.5 wt.%, based on the weight of the feedstock, using a 1 wt.% Ru/Zr02 catalyst at time intervals of 30 min (dark column), 1 h (dark grey column), 2 h (medium grey column), and 3 h (light grey column).

Figure 7 shows the production of GVL during the hydrogenation of a LA feedstock in the presence of no impurity, formic acid (FA) in an amount of 0.5 wt.% and acetic acid (AA) in an amount of 0.5 wt.%, based on the weight of the feedstock, using a 1 wt.% Ru/Zr02 catalyst at time intervals of 30 min (dark column), 1 h (dark grey column), 2 h (medium grey column), and 3 h (light grey column).

Figure 8 shows the production of GVL during the hydrogenation of a LA feedstock in the presence of no impurity, HMF in an amount of 0.5 wt.%, humins in an amount of 0.5 wt.% and guaiacol in an amount of 0.5 wt.%, based on the weight of the feedstock, using a 1 wt.% Ru/Zr02 catalyst at time intervals of 30 min (dark column), 1 h (dark grey column), 2 h (medium grey column), and 3 h (light grey column).

Figure 9 shows the production of GVL during the hydrogenation of a LA feedstock as a function of the number of recycling test using Ru/Zr02 catalyst and in the presence of 0.1 wt.% of H2SC for the methods A: the catalyst was washed with acetone after test (grey column); B: the catalyst has been washed with 250 niL of hot water (black column) and C: 10 wt% of water has been added to the LA feedstock and the catalyst was washed with acetone prior to recycling (reuse).

Figure 10 shows the STEM analysis of the unused, reduced Ru/Zr02 catalyst at different magnifications a) scale bar 50 nm and b) scale bar 10 nm BF-STEM images which demonstrate that the Zr02 agglomerates are devoid of discrete Ru nanoparticles; and c) and d) HAADF-STEM images showing atomically dispersed Ru decorating the Zr02 surface.

Figure 11 shows the STEM analysis of once-recycled Ru/Zr02 catalyst consisting of HAADF-STEM images with a) a discrete hep metallic Ru nanoparticle and, b) a more disordered Ru-containing nanoparticle, and c) a measured particle size distribution of the Ru-nanoparticles (not inclusive of the monatomic metal) in the once-recycled catalyst; and the STEM analysis of five times recycled Ru/Zr02 catalyst consisting of HAADF- STEM images of d) atomically dispersed Ru on Zr02 support, e) a

representative example showing a metallic hep Ru nanoparticle and f) a measured particle size distribution of the Ru-nanoparticles (not inclusive of the monatomic metal) in the five-times recycled catalyst.

The term "or" as used herein is defined as "and/or" unless specified otherwise.

The term "a" or "an" as used herein is defined as "at least one" unless specified otherwise.

The phrase "the metal catalyst on the support" is abbreviated herein after as "the metal catalyst" or "the catalyst".

The term "metal" is generally used herein in a strict sense, namely to refer to the metallic form of one or more elements, unless specified or evident otherwise (e.g. when referring to metal ions or to a metal salt). Thus, the term "metal catalyst" is used for a catalyst that comprises at least one catalytically active metallic element

(characteristically ruthenium). A specific form of a metal is an alloy. When referring to a noun (e.g. a compound, an additive, etc.) in the singular, the plural is meant to be included.

For the purpose of clarity and a concise description features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include

embodiments having combinations of all or some of the features described.

The term "substantial(ly)" or "essential(ly)" is generally used herein to indicate that it has the general character, appearance or function of that which is specified. When referring to a quantifiable feature, these terms are in particular used to indicate that it is for more than 50 %, in particular at least 75 %, more in particular at least 90 %, even more in particular at least 95 % of the maximum that feature.

The phrase "essentially consisting" of a substance (e.g. a metal or a support material, such as Zr02) as used herein, in general means that other components than said substance are not detectible or present at a level that is generally considered an impurity. In particular, "essentially consisting of means for more that 98 wt.%, more in particular for more than 99 wt.%, more in particular for more than 99.5 wt.%.

As used herein, the phrase "catalytic selectivity towards a specific useful compound" is defined (calculated) as ratio of the molar amount of the reactant (e.g. LA) converted to said compound (e.g. GVL) relative to the total molar amount of converted reactant (LA).

The term "impregnation" is also referred herein as "wet- impregnation" or "anion excess impregnation". The term "wet impregnation" as used herein, is defined as a wet impregnation without anion excess.

Preferably, the starting compound is derived from or is a renewable feedstock, such as lignocellulosic biomass, preferably LA.

Typically, the feedstock comprises a starting compound, a contaminant and a liquid. The phrase "weight of the feedstock" as used herein is defined as the combined weight of all the components present in the feedstock (e.g. a starting compound, a contaminant and a liquid). The liquid is usually an organic solvent and/or water.

In a preferred embodiment, the liquid is an organic solvent and water, wherein the amount of water present in the feedstock is from 1 wt.% to 50 wt.%, preferably 5 wt.% to 50 wt.%, more preferably 10 wt.% to 45 wt.%, and most preferably 10 wt.% to 40 wt.% based on the weight of the feedstock.

Surprisingly, the addition of water to the liquid was found to have a positive effect on the catalytic activity and stability in the method of the invention, in particular for converting LA to GVL in the presence of a sulfur compound contaminant (such as sulfuric acid), enabling the catalyst to be recycled/reused over a number of runs (i.e. repeating a chemical reaction using the same catalyst) without substantial loss of activity. This is believed to be due to the water acting to prevent the deposition of contaminants onto the surface of the catalyst. Suitable organic solvents are known in the art and may be selected from the list consisting of dioxane, alcohols, lactones, tetrahydrofuran (THF), hexalactone, γ-octalactone and GVL, and preferably GVL. The alcohols may be selected from linear alcohols (e.g. methanol, ethanol, n-butanol), branched alcohols (e.g. isoalcohols, such as isopropanol), cycloalkanols (e.g. cyclohexanol and phenols (e.g. phenol, alkylphenols). The advantage of using GVL as the solvent in the method of the invention is that it has a high stability in the presence of water and oxygen and a low toxicity and flammability risk.

Typically, the starting compound is selected from the group consisting of a levulinic acid source, alcohols, furans, and saccharides, and preferably the starting compound is a levulinic acid source.

Usually, the levulinic acid source is selected from the group consisting of levulinic acid, levulinic acid anhydrides, levulinic acid salts, levulinic acid esters, levulinic acid amides and combinations thereof, and preferably levulinic acid. Angelica lactone is a preferred LA lactone. In particular, good results have been achieved with levulinic acid.

The saccharide is usually selected from the group consisting of monosaccharides, disaccharides, oligosaccharides, polysaccharides and combinations thereof. Preferably, the saccharide is derived from

lignocellulose biomass. Monosaccharides and disaccharides are also known as "simple sugars" or "sugars". Suitable monosaccharides to be used in the method of the invention may be selected from the group consisting of C5 sugars and C6 sugars, in particular the group consisting of glucose, fructose, xylose, arabinose, ribose, rhamnose, galactose and combinations thereof. Suitable disaccharides to be used in the method of the invention may be selected from the group consisting of maltose, lactose, cellobiose, sucrose, and combinations thereof. Suitable oligosaccharides to be used in the method of the invention may be selected from the group consisting of aldohexoses, ketohexoses, aldopentoses, ketopentoses and combinations thereof. Suitable polysaccharides to be used in the method of the invention may be selected from the group consisting of cellulose, hemicellulose, chitin, starch, glycogen, pectins, arabinoxylans and combinations thereof, preferably cellulose or chitin. Preferably, the saccharide is a monosaccharide or disaccharide.

Usually, the furan is selected from the group consisting of furfural, hydroxylmethylfurfural, alkoxymethylfurfurals (e.g.

methoxymethylfurfural) and combinations thereof.

The alcohol is usually selected from the group of monoalcohols, polyols and combinations thereof. Suitable monoalcohols include linear or branched C1-C12 alcohols, and in particular the monoalcohol is selected from the group consisting of methanol, ethanol, propanol, butanol and combinations thereof. Suitable polyols may be selected from the group consisting of mannitol, xylitol, sorbitol, glycerol, maltitol and isosorbide, and in particular the polyol is glycerol or sorbitol. Usually, the contaminant is present in the feedstock in an amount of less than 5 wt. %, preferably in an amount of 0.02-3 wt.%, more

preferably in an amount of 0.03-2 wt. %, in particular in an amount of 0.05-1 wt. %, more in particular in an amount of 0.1-0.7 wt. %, even more in particular 0.1-0.5 wt. %, based on the weight of the feedstock. The amount of the contaminant present in the feedstock is defined herein as the amount of each individual contaminant present in the feedstock before the chemical reaction involving the metal catalyst and the starting compound

commences. Preferably, the contaminant is not used as a co-catalyst in the method of the invention. Typically, the total amount of all contaminants present in the feedstock is less than 50 wt.%. In a preferred embodiment the amount of the contaminant at the start of the reaction is in increasing order of preference less than 30 wt. %, less than 25 wt. %, less than 20 wt. %, less than 15 wt. %, less than 10 wt. %, less than 5 wt. %, less than 4 wt. %, less than 3 wt. %, less than 2.5 wt. %, less than 2 wt. %, less than 1.8 wt. %, less than 1.5 wt. %, less than 1.4 wt. %, less than 1.3 wt. %, less than 1.2 wt. %, less than 1.1 wt. % or less than 1.0 wt. %.

The contaminant is selected from the group consisting of sulfur compounds, halide salts, mineral acids and salts thereof, phenolics, lignins, humins, and combinations thereof, and preferably comprises a sulfur compound or a humin.

The sulfur compound may be selected from the group consisting of sulfur containing acids, sulfates, sulfides, sulfites and combinations thereof, in particular the sulfur compound is a sulfur containing acid, and more in particular the sulfur compound is selected from the group consisting of sulfuric acid, methane sulfonic acid, toluene sulfonic acid, benzene sulfonic acid, methionine, cysteine, cystine and combinations thereof, and even more in particular the sulfur compound is sulfuric acid. Usually, the halide salt is a metal halide salt. Suitable halides may be selected from the group consisting of fluoride, chloride, bromide and iodide, and preferably chloride or bromide.

Usually, the mineral acid and salt thereof is selected from the group consisting of sulfuric acid (H2SO4), phosphoric acid (H3PO4), hydrobromic acid (HBr), boric acid (H3BO3), hydrofluoric acid (HF), nitric acid (HNO3), perchloric acid (HCIO4) and hydrochloric acid (HC1) and salts thereof. The salt of the mineral acid (also known as "mineral salt") is usually a metal salt.

Humins are usually carbonaceous polymeric or oligomeric products of irregular molecular composition formed via a chemical reaction, such as, (cross-)condensation of sugars, sugar dehydration intermediates, HMF, and LA and other condensable molecules present (e.g. amino acids) during (hydro)thermal, acid-catalyzed conversion of sugars, or sugar- containing sources such as cellulose or whole biomass. Humin products are also typically referred to as humin-like substances or humic solids.

Typically, the amount of the chemical compound prepared in the presence of a contaminant is in increasing order of preference at least 25 %, at least 30%, at least 35 %, at least 40 %, at least 45%, at least 50%, at least 55%, at least 60 %, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% of the amount of that chemical compound when prepared in the absence of the contaminant(s) in a given time period under otherwise identical conditions. A given time period is typically determined by both the chemical reaction carried out and the chemical compound of interest and can be suitably chosen based on the information disclosed herein, the cited prior art and references cited therein, common general knowledge and optionally a limited amount of testing.

In a preferred embodiment, the metal catalyst used in the method of the invention, is obtainable by a metal-ion impregnation method, which metal-ion impregnation method uses an anion-excess or wet impregnation, and more preferably uses the wet impregnation, and, wherein said catalyst comprises ruthenium metal and optionally at least one other metal.

In a preferred embodiment, the metal catalyst as used in the method of the invention has a molar ratio of Zr:contaminant of at least 2:1, more preferably at least 4:1, even more preferably at least 5:1 most preferably at least 10:1, in particular of at least 15:1. Said ratio may be up to 150:1, up to 300:1 or even higher. The molar ratio of Ru to contaminant is in a preferred embodiment at least 1:40, more preferably at least 1:20, even more preferably at least 1:10, most preferably at least 1:6, in particular at least 1:4. Said ratio may be up to 2.5:1, 5:1 or even higher.

The reaction conditions of the method for preparing the chemical compound in a contaminant containing feedstock can also be chosen dependent on the chemical compound of interest (e.g. GVL), the starting compound (e.g. LA), the information disclosed herein, the cited prior art and references cited therein, common general knowledge and optionally a limited amount of testing.

As illustrated in the Examples, the catalyst can be used well under acidic conditions and under non-acidic conditions. Thus, in a first preferred embodiment, the chemical reaction is carried out in the presence of at least one contaminant under acidic conditions; in a second preferred embodiment, the chemical reaction is carried out in the presence of at least one contaminant under about neutral pH conditions; in a third preferred embodiment, the chemical reaction is carried out in the presence of at least one contaminant under alkaline pH conditions. The skilled person will be able to select preferred pH conditions, dependent on the specific chemical reaction used to produce the chemical compound, using the information disclosed herein and common general knowledge.

Usually, the chemical reaction catalyzed by the metal catalyst is selected from the group consisting of reduction reactions and oxidation reactions, preferably from the group consisting of hydrogenation reactions, dehydrogenation reactions and hydrogenolysis reactions. Preferably, the chemical reaction selected is catalyzed by a metal catalyst.

In a preferred embodiment, the chemical reaction used for converting a LA source is a hydrogenation reaction. Suitable reducing agents are preferably selected from the group of hydrogen, secondary alcohols, formic acid and formate salts, in particular a formate salt of formate and a monovalent cation, such as ammonium formate or sodium formate. Typically, formic acid is co-produced with LA source in sugar dehydration/reduction reaction and is consequently present in such LA sources. Preferably GVL is formed in the hydrogenation reaction.

The reaction conditions for hydrogenating LA source to GVL can be based on common general knowledge and the information provided in the present disclosure.

In particular, GVL is usually prepared at a temperature in the range of 25-250 °C, preferably at a temperature in the range of 120-230 °C, and more preferably at a temperature in the range of 150-220 °C.

In particular, GVL is usually prepared at a hydrogen pressure of 1-100 bar, preferably of 20-70 bar, in particular of 30-60 bar, and more in particular 20-50 bar.

In case formic acid ("hydrogen formate") or a formate salt is used, the molar ratio of formate to the LA-source is typically at least about 1. The formate can be applied in any excess, but usually the ratio of formate to the LA-source is 1000 or less, in particular 100 or less, and more in particular 10 or less.

The amount of catalyst can be chosen based on common general knowledge, depending on the type of reactor system.

The GVL prepared in accordance with the invention can be used in the preparation of another compound. In a specific embodiment, the GVL is subjected to an acid or base catalysed ring-opening reaction to produce a mixture of pentenoic acids.

In a specific embodiment, the GVL is subjected to an acid or base- catalysed ring-opening reaction in the presence of an alcohol to produce a mixture of alkyl pentenoates, preferably methyl pentenoates.

In a specific embodiment, the GVL is subjected to an acid or base- catalysed ring-opening in the presence of ammonia to produce a mixture of pentenenitriles. In these mixtures the double bond can be in the 2-, the 3- or the 4-position. Where applicable, the double bond may be cis or trans. These ring opening reactions can be advantageously performed in the gas phase or in the liquid phase. In the latter case the ring-opening reaction can advantageously be executed as a reactive distillation.

In a specific embodiment, the GVL is subjected to an acid or base- catalyzed reaction with an aldehyde to form an alpha-alkylidene-gamma- valerolactone. Preferably, the aldehyde used is formaldehyde which when used in the reaction forms alpha-methylene-gamma-valerolactone.

In a specific embodiment, the GVL is subjected to a reaction with ammonia or an N-alkylamine to form 5-methyl-pyrrolidinone or N-alkyl-5- methyl-pyrrolidinone. Preferably, the N-alkylamine used is methylamine, which when used in the reaction forms N-methyl-5-methyl-pyrrolidinone.

In a specific embodiment, the GVL is hydrogenated to form 1,5- pentanediol.

In a specific embodiment, the GVL is hydrogenated to form 2- methyltetrahydrofuran.

In a specific embodiment, the GVL is hydrogenated to form pentanoic acid.

In a specific embodiment, a LA-source is converted into a salt of 4- hydroxypentanoic acid or 4-hydroxypentanamide.

In a preferred embodiment, the invention relates to the use of gamma-valerolactone prepared in accordance with the invention in the production of a fuel; a monomer, in particular a monomer for the production of a polyamide; or a solvent. For instance GVL can be converted into methyltetrahydrofuran which is suitable for use as a solvent or a fuel.

In a preferred embodiment, the chemical reaction used for converting a furan, in particular HMF, to a chemical compound of interest is a hydrogenation reaction. The reducing agents are preferably selected from the group of hydrogen, formic acid, formate salts and alcohols, in particular an alcohol, such as 2-propanol. Preferably, DMF, 2,5-BHMF or 2,5-BHTHF is formed in the hydrogenation reaction.

The reaction conditions for hydrogenating HMF to form DMF,

2,5-BHTHF or 2,5-BHMF can be based on common general knowledge and the information provided in the present disclosure.

In particular, DMF, 2,5-BHTHF or 2,5-BHMF is usually prepared at a temperature in the range of 25-250 °C; DMF is preferably prepared at a temperature in the range of 120-230 °C, and more preferably at a temperature in the range of 180-220 °C; 2,5-BHTHF or 2,5-BHMF are preferably prepared at a temperature in the range of 50-180 °C, more preferably at a temperature in the range of 60-150 °C.

In particular, DMF, 2,5-BHTHF or 2,5-BHMF is usually prepared at a hydrogen pressure of 1-100 bar, preferably of 20-70 bar, in particular of 40-50 bar, and more in particular 20-40 bar.

The amount of catalyst for this hydrogenation reaction can be chosen based on common general knowledge, depending on the type of reactor system used.

The DMF, 2,5-BHTHF or 2,5-BHMF prepared in accordance with the invention can be used in preparation of another compound.

In a specific embodiment, the DMF is subjected to an acid- catalyzed reaction to produce p-xylene.

In a preferred embodiment, the chemical reaction used for converting a saccharide, in particular a saccharide selected from the group of monosaccharides, disaccharides and combinations thereof, to a chemical compound of interest is a hydrogenation reaction. The monosaccharides may be pentoses or hexoses. The disaccharides may be composed of two pentoses, two hexoses or a pentose and a hexose.

The reducing agent in a reduction or hydrogenation reaction is preferably selected from the group of hydrogen, secondary alcohols, formic acid and formate salts.

Preferably at least one sugar alcohol, more preferably a C5 sugar alcohol a C6 sugar alcohol, or both are formed in the hydrogenation reaction.

The reaction conditions for hydrogenating monosaccharides or disaccharides to form the sugar alcohol, can be based on common general knowledge and the information provided in the present disclosure.

In particular, the sugar alcohol is prepared at a temperature in the range of 25-200 °C, preferably at a temperature in the range of 120-180 °C, and more preferably at a temperature in the range of 120-150 °C.

In particular, the sugar alcohol, is prepared at a hydrogen pressure of 1-100 bar, preferably of 20-70 bar, in particular of 40-50 bar.

The amount of catalyst for this hydrogenation reaction can be chosen based on common general knowledge, depending on the type of reactor system used, and the information disclosed herein.

The sugar alcohol, prepared in accordance with the invention can be used in preparation of another compound.

In a specific embodiment, the sugar alcohol is subjected to a dehydration reaction to produce their corresponding cyclic ethers.

In a preferred embodiment, the chemical reaction used for converting a saccharide, in particular a saccharide selected from the group of monosaccharides, disaccharides and combinations thereof, to a chemical compound of interest is an oxidation reaction. The oxidizing agent is preferably selected from the group of molecular oxygen or air. Preferably, at least one compound selected from the group of lactones, bislactones, and C5- C12 sugar acids is formed in the oxidation reaction.

The reaction conditions for oxidizing a monosaccharide or disaccharide to form a sugar acid, a lactone or a bislactone can be based on common general knowledge and the information provided in the present disclosure.

In particular, the sugar acid, lactone or bislactone is prepared at a temperature in the range of 25-150 °C, and preferably at a temperature in the range of 25-100 °C.

The amount of catalyst for the oxidation reaction can be chosen based on common general knowledge and the information disclosed herein, depending on the type of reactor system used.

In a preferred embodiment, the chemical reaction used for converting glycerol or sorbitol to a chemical compound of interest is a hydrogenolysis reaction. Preferably, butanediols, propanediols, 1,2-ethylene glycol, or glycerol are respectively formed in the hydrogenolysis reaction.

The reaction conditions for the hydrogenolysis of glycerol or sorbitol to form butanediols, propanediols, 1,2-ethylene glycol, or glycerol, respectively, can be based on common general knowledge and the

information provided in the present disclosure.

In particular, butanediols, propanediols, 1,2-ethylene glycol, or glycerol are prepared at a temperature in the range of 25-250 °C, preferably at a temperature in the range of 120-230 °C, and more preferably at a temperature in the range of 180-220 °C.

In particular, butanediols, propanediols, 1,2-ethylene glycol, or glycerol are prepared at a hydrogen pressure of 1-150 bar, preferably of 20-

70 bar, in particular of 40-50 bar. The amount of catalyst for this hydrogenation reaction can be chosen based on common general knowledge and the information disclosed herein, depending on the type of reactor system used.

The butanediols, propanediols, 1,2-ethylene glycol, or glycerol prepared in accordance with the invention can be used in preparation of another compound.

In a specific embodiment, glycerol is subjected to a dehydration reaction to produce acrolein.

The catalyst of the invention comprises ruthenium and optionally one or more other metals on a zirconium oxide support.

In a specific embodiment, the metal consists essentially of ruthenium.

In another specific embodiment, the metal of the metal catalyst comprises ruthenium and at least one other metal selected from the group of platinum, palladium, iridium, rhodium, rhenium, silver, gold, molybdenum, copper, cobalt and nickel, preferably palladium, rhenium or platinum.

Ruthenium and the other metal(s) preferably form an alloy. A preferred alloy essentially consists of ruthenium and at least one of palladium and platinum. An alloy of ruthenium and palladium, in particular an alloy essentially consisting of ruthenium and palladium, has been found to be particularly advantageous in the metal catalyst, in particular when said catalyst is obtained by an anion excess impregnation method, due to its high catalytic activity, selectivity toward GVL and stability.

The molar ratio of the total of the metals other than ruthenium (such as palladium or platinum) to ruthenium in this embodiment can be chosen within wide limits, usually in the range of 1:99 to 90:10, in particular in the range of 5:95 to 80:20, and more in particular in the range of 20:80 to 70:30. If palladium is present, the ratio of palladium to ruthenium is preferably at least 10:90, in particular at least 30:70, and more in particular at least 40:60. In general, the higher the palladium content, the longer the metal catalyst maintains a satisfactory selectivity, in particular towards GVL.

The total metal concentration usually is in the range of 0.1-20 wt.%, in particular in the range of 0.5-15 wt.%, more in particular 1- 10 wt.%, even more in particular 1.0-5 wt.%, and preferably 1.5-5.0 wt.%, based on the weight of the metal catalyst. The weight percent of the total metal concentration, as defined herein, is based on the weight of the reduced metal catalyst.

The metal catalyst usually contains at least 0.1 wt.% ruthenium, based on the total weight of metal(s) and support (of the reduced catalyst), preferably at least 0.3 wt.% ruthenium, in particular at least 0.5 wt.% ruthenium. The ruthenium content of the metal catalyst, based on the total weight of metal(s) and support (of the reduced catalyst) usually is less than 10 wt.%, preferably 5 wt.% or less, in particular 2 wt.% or less.

In a specific embodiment, the support consists essentially of zirconium oxide. The zirconium oxide used in the support may have a monoclinic, tetragonal or cubic crystal structure, and preferably is

monoclinic. Such a support has been found to be advantageously suitable for a catalyst suitable for converting a starting compound (e.g. LA) in a contaminant (e.g. H2SO4) containing feedstock into a valuable compound of interest (e.g. GVL) due to its resistance to poisoning.

In another specific embodiment, the support comprises zirconium oxide and at least one other support material selected from the list consisting of titanium oxide, silica, alumina, silica-alumina, zinc oxide, magnesium oxide, calcium oxide, metal silicates, metal aluminates, zeolites, cerium oxide, yttrium oxide, hafnium oxide, niobium oxide, carbon and combinations thereof.

The size of the support material is not critical. Usually, when preparing the metal catalyst on a support a particulate support is provided, such as a powder. In an advantageous embodiment for the preparation of the catalyst, the particles are microparticles (particles typically having a size < 1 mm, in particular in the range of 1-200 micrometer). After the catalyst has been prepared, it may be used as such or may be shaped in a desired form, e.g. pelletized.

In an embodiment, the metal catalyst has a BET surface area of between 10-1000 m ² /g, in particular 30-600 m ² /g, and more in particular 50- 200 m ² /g. In particular for a Zr02 support, the BET surface area is advantageously in the range of 10-150 m ² /g, in particular in the range of 30- 150 m ² /g. The BET surface defined herein, is the value measured by determining the amount of nitrogen adsorbed at 77 K and P/Po of

approximately 0.3 and assuming a nitrogen cross sectional area of 16.2 A ² , after degassing the sample at 250 °C on Micromeritics ASAP 2420.

In a preferred embodiment, the metal catalyst has a total pore volume of 0.1-1.0 cm ³ /g, more preferably 0.1-0.7 cm ³ /g, in particular 0.2-0.5 cm ³ /g. The total pore volume is measured by determining the volume of liquid nitrogen adsorbed at P/ Po of approximately 1 using Micromeritics ASAP 2420. In a specific embodiment, the metal catalyst also typically has an average pore diameter in the range of 0.5-100 nm, in particular in the range of 1-50 nm, and more in particular in the range of 2-20 nm. The average pore diameter is determined by dividing the total pore volume by the BET surface area, and assuming that the pores are cylindrical. The BJH method is used to calculate the pore distributions from experimental isotherms using the Kelvin model of pore filling.

In an advantageous embodiment, the metal on the support is present on the support surface in the form of metal atoms (monoatomic) and/or nanoparticles having an average particle size in the range of 0.1 to less than 100 nm, in particular 0.1 to 20 nm, more in particular less than 0.1 to 10 nm, even more in particular 0.1-5 nm, and preferably 0.1 -4 nm. Typically, the average particle size of the metal atoms and/or nanoparticles of the catalyst, as defined herein, is the value determined by high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) images using an aberration corrected JEM ARM 200CF microscope operating at 200kV. Particle size distribution analysis was performed from the HAADF-STEM images using Image J.

In a preferred embodiment, the metal on the support is present on the support surface in the form of nanoparticles having an average particle size in the range of 0.5 to less than 100 nm, in particular 0.5-20 nm, more in particular 0.5-10 nm, even more in particular 0.5-5 nm, and preferably 1-4 nm, and more preferably in the form of metal clusters, deposited on the support. These metal clusters preferably have a particle size in the range of 0.5 to 10 nm.

It is further contemplated that— in an advantageous embodiment - a metal catalyst obtainable by anion excess impregnation in accordance with the invention is characterisable by a relatively high abundance of metal clusters present on the support, more preferably clusters having a size of about 0.5 to 5 nm and/or a relatively low polydispersity with respect to the particle size distribution of the metal nano-particles. Without being bound by theory, it is contemplated that in the case that metal catalyst is prepared using excess anions— in particular chloride ions— that these ions stabilise relatively small ruthenium or ruthenium-palladium alloy nanoparticles or clusters. Chloride is in particular considered favourable for realising a random alloy formation. Further, the inventors have found that an advantage of preparing a metal catalyst by the method of anion excess impregnation is that even if a halide salt is used in the preparation of said catalyst, that the reduced catalyst obtained by this method is essentially free of halides, as determined by XPS.

With respect to the metal catalyst, wherein the metal is an alloy, it is further contemplated that— in an advantageous embodiment— the metal-alloy is characterisable by an essentially homogeneous distribution of ruthenium and the other metal(s), in particular a random alloy structure, rather than e.g. a core- shell alloy which one would expect to perform differently. It has further been found that a metal catalyst wherein the metal is a metal alloy, in particular an alloy of ruthenium and palladium, in particular a metal catalyst wherein the metal is a metal alloy obtained by anion excess impregnation method, the particle size stability of the metal particles is improved, compared to particles of a single metal, such as only ruthenium or only palladium.

In an advantageous embodiment - a metal catalyst obtainable by wet impregnation in accordance with the invention, typically comprises an essentially monoatomic dispersion of Ru metal on the support of the reduced catalyst, which following use in a chemical reaction results in the occurrence of metal nanoparticles in combination with the monatomic dispersion of Ru metal on the support. Surprisingly, the presence of metal atoms on the support of the unused catalyst of the invention occurred with a high metal loading (e.g. at least 1 wt.%), since in the literature almost exclusively atomically dispersed Ru atoms have been seen only at a metal loading an order of magnitude lower. Further, replacing the Zr02 substrate of the catalyst of the invention with T1O2 did not result in the occurrence of a monoatomic Ru dispersion on the T1O2 support only Ru nanoparticles.

The metal catalyst may be prepared by a metal-ion impregnation method of either a wet impregnation method or an anion excess

impregnation method.

In a method for preparing the metal catalyst on a support an impregnation solution is provided comprising a precursor for the metal catalyst. The liquid phase is usually a polar solvent, in particular a highly polar solvent, such as an aqueous liquid. As used herein "highly polar" means having about the same polarity as water or a higher polarity than water.

The metal precursor, such as the ruthenium precursor and optionally at least one other metal precursor selected from the group of platinum, palladium, iridium, rhodium, rhenium, silver, gold, molybdenum, copper, cobalt, and nickel, preferably palladium or platinum, usually is a metal salt dissolved in water or an aqueous liquid. Examples of metal salts which are suitable for use in the anion excess impregnation method are halogen salts (e.g. chloride, fluoride, iodide and bromide) and organic acid salts. Examples of metal salts which are suitable for use in the wet impregnation method are nitrate salts.

In a specific embodiment, good results have been achieved with a chloride salt when used in the anion excess impregnation method. Chloride has been found in particular to contribute to providing a catalyst with good catalytic properties. Preferably the impregnation solution used in the anion excess impregnation method is essentially free (less than 1 wt.%) of nitrates and/or sulfates.

In a specific embodiment, good results have also been achieved with the wet impregnation method when the nitrate salt is a nitrosyl nitrate.

The total concentration of the metal ions used in the wet impregnation method or the anion excess impregnation method is usually in the range of 1 mg metal ions/mL to 100 mg metal ions 1/mL, in particular in the range of 2 mg metal ions /mL to 25 mg metal ions /mL, preferably in the range of 3 mg metal ions/mL to 10 mg metal ions /mL.

In the wet impregnation method, the source of anions in the impregnation solution used is typically from the salt serving as the source for the metal ions which serve as the precursor for the catalytic metal.

In the anion excess impregnation method, the impregnation solution used typically comprises an additional source of anions, in addition to the anions from the salt serving as the source for the metal ions which serve as the precursor for the catalytic metal. This additional source of anions may be selected from the group of acids and salts of anions with volatile bases, in particular from the group of HC1, organic acids, ammonium chloride and salts of ammonium and an organic acid. The concentration of the acid or salt of the anions and a volatile base used in the anion excess impregnation method, preferably is 10-100 mL of a 0.1-10 M solution, in particular 15-30 mL of a 0.1 to 5 M solution, per 0.5 to 5 gram support.

The wet impregnation method or the anion excess impregnation method may be carried out based on methodology known per se.

The support is advantageously mixed with the impregnation solution by agitation, for instance by vigorous stirring, e.g. using a magnetic bar/stirrer set-up above 900 rpm, whereby the mixing of support and impregnation liquid is effected. The impregnation method can be carried out at any temperature between the melting point and the boiling point of the liquid phase, and is advantageously carried out at ambient temperature, e.g. at about 25 °C. During or after mixing of the support with the impregnation solution, the temperature is preferably raised to about 50-90 °C. This will allow evaporation of the solvent at a desired evaporation rate.

The impregnated support prepared by both impregnation methods is typically dried. Drying may be carried out in a manner known per se. In particular good results have been achieved with a method wherein the slurry of support in the impregnation solution is dried in hot open air atmosphere typically at a temperature in the range of 50-95 °C. The drying is preferably carried out whilst agitating the slurry, for instance by stirring or drying in a fluidized bed. The agitation is preferably vigorous enough to achieve intensive mixing of the contents of the slurry. The drying is usually continued until a visually dry product is obtained. The drying usually takes 24 hours or less, in particular 1-20 hours, more in particular 5-20 hours.

If desired, the dried product is ground, prior to reduction. In a specific embodiment, the dried impregnated support is calcined prior to reduction. Thus, in this embodiment the catalyst is a calcined catalyst. Typically, the catalyst prepared by the wet impregnation method is calcined prior to reduction. The dried impregnated support is calcined at a temperature usually in the range of 300-700 °C. The

calcination is preferably carried out for a period of at least 1 h, in particular for a period of 2 h to 10 h. Preferably, the temperature is gradually raised until the desired maximum temperature is reached, in particular at a ramp- rate in the range of 1-5 °C/min.

In a specific embodiment, the dried impregnated support is reduced without first having been subjected to a calcination step. Thus, in this embodiment the catalyst is a non-calcined catalyst. Typically, the catalyst prepared by the anion excess impregnation is reduced without first having been subjected to a calcination step. As is generally known,

'reducing' means that the metal ions that are the precursor for the metal catalysts are reduced from the ionic state to the metallic state (oxidation state = 0). In the art, calcination is generally known as a heat treatment of a catalyst precursor in an oxidizing atmosphere (of variable composition) for variable amount of time and at a temperature sufficient to convert essentially all precursors into oxides, i.e. to remove essentially all anions except oxygen as well as any solvent molecules.

Reduction is preferably carried out using hydrogen, for instance 1- 10 vol.% hydrogen in an inert gas, such as nitrogen, argon and/or helium. The reduction is preferably carried out at a temperature in the range of 250 °C to 600 °C. Preferably, the temperature is gradually raised until the desired maximum temperature is reached, in particular at a ramp-rate in the range of 1-5 °C/min.

The reduction is preferably carried out for a period of at least 1 h, in particular for a period of 2 h to 10 h.

The resultant metal catalyst on the metal support prepared by the impregnation method is then allowed to cool.

In a specific embodiment, the metal catalyst is regenerated (recycled/reused) between chemical reactions (i.e. runs) by carrying out a rinsing step wherein the metal catalyst is rinsed with a liquid, wherein preferably said liquid comprises water, having a temperature of at least 80- 120 °C, after which it is typically dried as described hereinabove.

Surprisingly, this method enables the performance of the metal catalyst to be restored/maintained without any substantial loss of activity or

selectivity. It is believed, without being bound to any theory, that by carrying out this rinsing step the surface of the metal catalyst is essentially cleaned of any deposits present. Preferably, the used (spent) catalyst is rinsed with an organic solvent, such as acetone, prior to recycling/reuse.

The invention is illustrated by the following examples.

Example 1

Preparation of 1 wt.% Ru/ZrQ2 catalyst

A 1 wt.% Ru/Zr02 catalyst was prepared using a wet

impregnation method.

RuNO(N03)3 (Alfa Aesar) was used as the ruthenium precursor and was dissolved in deionized water to form an aqueous precursor solution with a ruthenium concentration of 4 mg / mL.

Monoclinic Zr02 (Degussa) was used in the amount of 3 g as the support which was crushed and then dried for 2 h at a temperature of 393 K, after which the support was dispersed in 50 mL distilled water in a clean 100 mL round bottom flask fitted with a stirrer and was stirred at 450 rpm for 30 min. 10 mL of the precursor solution was added to the slurry and then the slurry mixture was stirred for 1 h. After evaporation of the water under vacuum at 333 K, the catalyst was dried at a temperature of 333 K overnight under static air, calcined at a temperature of 773 K for 3.5 h with a heating ramp 5 K/min under a N2 flow of 100 mL/ min, followed by reduction at a temperature of 723 K, for 5 h, under a H2 flow of 80 mL/min.

The following properties of the catalyst of Example 1 were determined and are shown in Table 1 below. The BET surface area (BET SA), total pore surface area (TPSA) (also known as the BJH Adsorption cumulative surface area of pores; as determined by N2 physisorption isotherms with a Micromeritics Tristar 3000 setup operating at 77 K, in which the samples were outgasses prior to performing the measurement for 20 h at 473 K in a N2 flow), the total pore volume (TPV) and the average pore diameter (APD) of the catalyst was determined as described hereinabove.

The average particle size (APS) of the Ru metal particles for Example 1 was measured using transmission electron microscopy (TEM) on a TECNAI 20FEG microscope, and using HAADF-STEM on an aberration corrected JEM ARM 200CF microscope operating at 200kV to take images which were analyzed using Image J.

Table 1

# APS of the Ru metal particles determined using TEM on a TECNAI 20FEG microscope

* APS of the Ru metal particles determined using HAADF-STEM on an aberration corrected JEM ARM 200CF microscope operating at 200kV to take images which were analyzed using Image J

These results in Table 1 show that the presence of monoatomic Ru on the support could only be determined using the technique of HAADF-STEM on an aberration corrected JEM ARM 200CF microscope operating at 200kV, due to the higher resolution and strong contrast obtainable using this imaging technique.

Example 2

Preparation of 0.5 wt.% Ru/ZrQ2 catalyst A 0.5 wt.% Ru/Zr02 catalyst was prepared according to the same method as described for Example 1, with the exception that the aqueous precursor solution had a ruthenium concentration of 2 mg / mL. Method of testing the catalysts

Reactions were performed with a feedstock of 10 wt.% levulininc acid (3 g, 25 mmol) in dioxane (27 g) with varying amounts of the catalysts. The reactions were run in a 50 mL Parr batch autoclave at a temperature of 423 K using a hydrogen pressure of 50 bar and a stirring speed of 1250 rpm. In a typical reaction, the batch autoclave reactor was loaded with the catalyst, starting compound (i.e. levulinic acid), contaminant (i.e. sulfuric acid and/or sodium sulfate; HC1; NaCl; H ₃ P0 ₄ ; FA; AA; HMF; humins;

guaiacol) and the solvent (i.e. dioxane); purged three times with argon after which the reaction mixture was heated to reaction temperature (i.e. 423 K under standard conditions) and charged with ¾ to 50 bar. This was taken as the starting point of the reaction; during the reaction samples were typically taken regularly and 1 wt.% of anisole was added as an internal standard to the samples. After the reaction, the autoclave was cooled to room temperature (i.e. 293-298 K), the ¾ was released and 1 wt.% anisole was added as an internal standard. The catalyst was separated by filtration.

The reaction products were analyzed using a Shimadzu GC-2010A gas chromatograph equipped with a CPWAX 57-CB column (25 m x 0.2 mm x 0.2 μηι) and FID detector. Products were identified with a GC-MS from Shimadzu with a CP-WAX 57CB column (30 m x 0.2 mm x 0.2 μηι).

Results

Test 1: Influence of H2SO4 on the catalyst of Example 1 The activity and selectivity of the 1 wt.% Ru/Zr02 catalyst in hydrogenating LA to GVL in the presence of H2SO4 in an amount of 0.1-5 wt.%, based on the weight of the feedstock was determined for a reaction time of 1 h. A LA/Ru molar ratio of 350 was used for these experiments. The results of these experiments are shown in Figure 1. From Figure 1 it can be seen that for H2SO4 in the amounts of in the range of 0.1-0.5 wt.%, that LA could be converted to GVL with yields above 65 %. Figure 1 also shows the LA conversion which is above 70 % for H2SO4 in the amounts of in the range of 0.1-0.5 wt.%. In addition, Figure 1 shows the Zr/S molar ratio for all the reactions and that even at a value of a molar ratio of about 5, GVL yields above 65 % could be achieved. Test 2: Influence of H2SO4 on 5 wt.% Ru/C reference catalyst

The activity and selectivity of a 5 wt.% Ru/C reference catalyst (Ruthenium, 5 wt. % on carbon; Sigma-Aldrich; product # 206180-25G) was determined similarly to that of Test 1 above, with the exception that the hydrogen pressure was 30 bar and the amounts of H2SO4 used was in the range of 0-0.1 wt.%. A LA/Ru molar ratio of 500 was used for these experiments. The results of these experiments are shown in Figure 2. From Figure 2 it can be clearly seen that the sensitivity of this catalyst toward the presence of sulfuric acid is much higher than the catalyst of Example 1, as it deactivates at much smaller amounts of H2SO4. Figure 2 also shows the LA conversion is about 10 %, in the presence of the contaminant H2SO4 in the amount of 0.05 wt.%. In addition, Figure 2 shows the Ru/S molar ratio for these reactions.

Test 3: Influence of H2SO4 on the activity/selectivity/stability of different catalysts

The activity and selectivity of a number of different catalysts was determined similarly to that of Test 1 above, with the exception that the reaction times were up to 100 h and the amount of H2SO4 used was only 0.1 wt.%. The different catalysts tested included the 5 wt.% Ru/C reference catalyst (Sigma-Aldrich), the 1 wt.% Ru/Zr02 catalyst of Example 1 and 5 wt.% Ru and 10 wt.% of Mo and Re, respectively, of the bimetallic RuMo/C and RuRe/C reference catalysts. The RuRe/C and RuMo/C catalysts were prepared according to the method as described in the literature (Braden, D.J. et al. Green Chem. 13 (2011) 1755-1765). A LA/Ru molar ratio of 350 was used for these experiments. The results of these experiments are shown in Figure 3. From Figure 3 it can be seen that both bimetallic catalysts are more active compared to the Ru/C reference catalyst. Nevertheless, reaction times of 80 to 100 h for these bimetallic catalysts are required to achieve GVL yields above 50%. In contrast, the Ru/ZrCh catalyst obtained high GVL yields in only a few hours of reaction (2-3 h). This clearly demonstrates the advantage of the method of the invention.

Test 4: Influence of the Ru loading on the Zr02 support

The activity and selectivity of the catalysts of Examples 1 and 2 were determined similarly to that of Test 1 above, with the exception that the reaction times were 3 h and the amount of H2SO4 used was only 0.1 wt.%. A LA/Ru molar ratio of 700 (0.37 g of 1 wt.% Ru/Zr0 ₂ and 0.75 g of 0.5 wt.% Ru/ZrC ) was used for these experiments. The results of these experiments are shown in Figure 4. From Figure 4 it can be seen that the catalyst of Example 2 obtained almost complete conversion of LA to GVL yield of 99.6 %, which was higher than the catalyst of Example 1 which had a GVL yield 86.4%. Both the catalysts of Examples 1 and 2 clearly outperform the other catalysts tested in Tests 2 and 3, which again demonstrates the advantages of using such catalysts in the method of the invention.

Test 5: Influence of contaminants on monometallic Ru supported catalyst

The activity and selectivity of the catalyst of Example 1 was determined similarly to that of Test 1 above, except that different contaminants were tested and the reaction time was up to 3 h. The first contaminants used were Na2S0 ₄ , in an amount of 0.7 wt.% (equimolar amount of sulfate anion as in 0.5 wt.% of H2SO4) and a mixture of

Na2S04 H2S0 ₄ in an amount of 0.7 wt. % and 0.1 wt.%, respectively. The result of these experiment were that Na2S0 ₄ and Na2S0 ₄ /H2S0 ₄ were found not to influence the activity or selectivity and a high GVL yield was obtained. The results of this test are shown in Figure 5. These results indicate that the catalyst of the invention is not sensitive to sulfate as a contaminant in the hydrogenation process of LA.

The next contaminants used were HC1 in amounts of 0.5 wt.%, 0.1 wt.% and 0.05 wt.%, NaCl in an amount of 0.5 wt.%, and HsP0 ₄ in an amount of 0.5 wt.%. The results of these tests are shown in Figure 6. These results show that HC1 strongly deactivates the catalyst of the invention, even when used in small amounts and is due to chloride poisoning of the Ru- catalyst. Surprisingly, the results for HsP0 ₄ indicate that the catalyst of the invention is not sensitive to it as a contaminant in the hydrogenation process of LA.

The performance of the Ru metal on zirconium oxide was also assessed by employing two organic acids as contaminants, these were formic acid (FA) and acetic acid (AA). The results of these tests are shown in Figure 7. The results show that for both contaminants a high GVL yield was obtained after three hours of carrying out the hydrogenation reaction.

However, Figure 7 shows that unlike the contaminant AA, the presence of FA resulted in some temporary reversible inhibition during the first two hours of the hydrogenation reaction since there were substantially no GVL yields obtained. This is believed to be because the decomposition products of FA (i.e. CO) covering the surface of the ruthenium, which are then removed, e.g. by the water gas shift (WGS) reaction, resulting in the LA being rapidly converted again. The effect of the contaminants hydroxymethylfurfural (HMF), humins and guaiacol was also assessed. The results of these tests are shown in Figure 8. Figure 8 shows that the addition of humins and guaiacol did impact the activity of the catalyst with full conversion of LA and maximum GVL yields only being obtained after 2 h of reaction instead of 1 h. A more pronounced effect was seen for added HMF in Figure 8, with high GVL yields only being obtained after 3 h of reaction. The initial reversible inhibition of activity due to the presence of HMF is similar to that shown in Figure 7 for formic acid.

Test 6: Effect of water added to LA feedstocks containing H2SO4 impurity (0.1 wt.%) in the recvclability of Ru/Zr02

The ability of the catalyst according to Example 1 to be recycled and reused again in a hydrogenation reaction (i.e. a run) was assessed after use in the hydrogenation reaction according to Test 1 by three different methods: (A) the catalyst was rinsed with 100 mL of acetone and then dried at 333 K overnight for about 18 h; (B) the catalyst was rinsed with 250 mL of water having a temperature of 373 K (i.e. hot water), followed by drying overnight at a temperature of 333 K under static air; and, (C) 10 wt.% water was added to the feedstock and the catalyst had been rinsed with acetone after Test 1 prior to assessment. The activity and selectivity of the recycled catalyst of Example 1 were determined similarly to that of Test 1 above, with the exception that the reaction times were 3 h. A LA/Ru molar ratio of 700 (0.37 g of 1 wt.% Ru/Zr0 ₂ and 0.75 g of 0.5 wt.% Ru/Zr0 ₂ ) was used for these experiments.

The results of these experiments are shown in Figure 9. From Figure 9 it can be seen that method (A) is not sufficient as after the first recycling more than 90% of the catalyst's activity was lost. In contrast, method (B) showed that the rinsing with hot water lead to the spent catalyst being able to be recycled up to four times without any loss of activity or selectivity. Only in the fifth run (fourth recycle), the first signs of

deactivation occurred, with the γ-valerolactone (GVL) yields decreasing from 95% till 85%. This latter drop is thought to be due to gradual buildup of carbonaceous deposits. Method (C) also showed improved results in comparison with method (A), with it being possible to maintain the catalyst's stability for up to four runs, after which the activity dropped with yields of GVL only 60% in the fifth run (fourth recycle).

Test 7: STEM characterization of Ru/ZrO2 (unused, once recycled and five-times recycled catalyst) tests

STEM images were taken of a unused, once recycled and five- times recycled catalyst of Example 1 in a hydrogenation reaction according to Test 1, with the exception that no contaminant was present. Samples for examination by STEM by dry dispersing the catalyst powder onto holey carbon supported by a 300 mesh copper TEM grid. Bright filed (BF) and

HAADF STEM images were both taken using an aberration corrected JEM ARM 200CF microscope operating at 200kV. Particle size distribution analysis was performed from the HAADF-STEM images using Image J.

The results for the unused catalyst are shown in Figure 10.

Figure 10 shows BF-STEM images at different magnifications a) scale bar 50 nm and b) scale bar 10 nm; and c) and d) shows HAADF-STEM images of a unused catalyst of Example 1. Both Figure 10 a) and b) show that the ZrO2 agglomerates are essentially devoid of discrete Ru nanoparticles. Figure 10 c) and d) show atomically dispersed Ru on the ZrO2 surface. Ru atoms dispersed on the ZrO2 support material could be visualized by virtue of its higher atomic number (Z = 44) as compared to the atoms making up the support (ZZr =40, ZO = 8). Figure 10 also shows that the Ru atoms were consistently found to be located on the Zr column sites of the ZrO2 support.

The results for the once recycled and five-times recycled catalyst are shown in Figure 11. Figure 11 a) and b) shows that after having been recycled once (i.e. used twice in catalysis), some changes in the Ru phase of the Ru/Zr02 material occurred, in that some discrete Ru nanoparticles were detected, although majority of the Ru metal remained in atomically dispersed form. Further, Figure 11 a) shows that the lattice fringes in some of the particles could be indexed to hep Ru metal, while in Figure li b) the Ru particles were more disordered in character. Figure 11 c) shows a particle size distribution of this rather sparse population of Ru particles which had an average particle size of 3.3 nm. Figure li e) shows that after the fifth recycle (reuse), the Ru/Zr02 catalyst exhibited many more discrete Ru nanoparticles, however in Figure 11 d) a small fraction of atomically dispersed Ru could still be detected on some Zr02 support grains. Most of the supported Ru nanoparticles in this sample measured showed lattice fringe spacings and intersection angles that were consistent with hep Ru metal. Figure 11 f) shows a particle size distribution of the Ru nanoparticles which had an average particle size of 2.8 nm. Figures 10 and 11 not only demonstrate that the structural features of the Zr02 support does not change and that it is stable under the reducing conditions, but also reveal some evolution in Ru speciation (i.e. from a monoatomic Ru dispersion to Ru nanoparticles).