EP4658633A1

EP4658633A1 - A process for preparing one or more of a mono-alcohol, a diol and a triol, each having two or three carbon atoms

Info

Publication number: EP4658633A1
Application number: EP24703029.9A
Authority: EP
Inventors: Jean-Pierre Berkan LINDNER; Moritz Otto HAUS; Marius Kirchmann; Kirsten Braunsmann; Alexander Czaja; Thomas Heidemann; Dagmar Pascale Kunsmann-Keitel
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2023-02-03
Filing date: 2024-02-01
Publication date: 2025-12-10
Also published as: WO2024160963A1; KR20250143326A; JP2026505895A; CN120641385A

Abstract

The present invention relates to a process for preparing one or more of a mono-alcohol, a diol and a triol, each having two or three carbon atoms and more specifically to a process preparing one or more of a monoalcohol, a diol and a triol, employing a catalyst comprising nickel, wherein the catalyst comprises zirconium oxide, wherein from 5 to 60 wt.-% of the catalyst consist of zirconium oxide, calculated as ZrO₂.

Description

A process for preparing one or more of a mono-alcohol, a diol and a triol, each having two or three carbon atoms

The present invention relates to a process for preparing one or more of a mono-alcohol, a diol and a triol, each having two or three carbon atoms and more specifically to a process preparing one or more of a mono-alcohol, a diol and a triol, employing a catalyst comprising nickel, wherein the catalyst comprises zirconium oxide, wherein from 5 to 50 wt.-% of the catalyst consist of zirconium oxide, calculated as ZrC>2.

The chemical industry has identified the need to reduce product carbon footprints, i.e. the amount of carbon dioxide equivalent emissions per unit of output. Thus, the use of renewable feedstocks derived from biomass is receiving growing attention. A subclass of these feedstocks are sugars and common sugar derivatives, such as sugar alcohols.

It is known that sugar alcohols, such as sorbitol, can be reacted with hydrogen (hydrogenolysis reaction) to obtain diols, triols and polyols, alcohols and even alkanes. Among these products, 1 ,2-propanediol (1 ,2-PDO, PDA, propylene glycol) and ethylene glycol (EG) have received most attention, due to potential use as formulation additives in the polymer, food, feed, agro, personal care and homecare industry. It is also known that the selective conversion of sorbitol to said glycols requires specific reaction conditions and additives. Most notably, alkaline and earth alkaline metal hydroxides are added to the aqueous and I or alcoholic sorbitol feed mixture.

However, the use of dissolved bases in addition to the required hydrothermal conditions pose an immediate problem to the stability of the employed catalyst. Accordingly, catalyst stability is named as a persistent challenge in a recent summary of heterogeneous catalyst research for sorbitol hydrogenolysis (Journal of Environmental Chemical Engineering 2022, 10, 107229; DOI: 10.1016/j.jece.2022.107229). Wang et al. (ChemCatChem 2019, 11 , 4123-4129; DOI: 10.1002/cctc.201900299) presented a catalyst comprising Cu and an activated carbon carrier. During subsequent batch reactions with an aqueous sorbitol feed (5 wt.-%) and Ca(OH)2 as additive, catalyst activity decreased continuously. This indicated a lack of catalyst stability under the tested reaction conditions (240 °C, 50 bar).

Attempts at operating without base additive were also discussed in the academic literature. For example, Xin Jin et al. (ACS CataL 2015, 5, 6545-6558; DOI: 10.1021 /acscatal.5b01324), presented a catalyst comprising Cu, CaO and AI2O3 and discussed its use for the hydrogenolysis of sorbitol (0.18 mol/L). Even without the addition of hydroxide base, the catalyst was unstable at 230 °C and 76 bar, leading to continuously decreasing substrate conversion in successive batch experiments. Chen et al. (Catalysis Communications 2013, 39, 86-89; DOI: 10.1016/j.cat- com.2013.05.012) presented a catalyst comprising Ni and MgO and tested the conversion of aqueous sorbitol solution (20 wt.-%). The applied reaction conditions led to an erosion of the support (MgO) and decreased sorbitol conversion. In the above prior art, it is likely that basic oxides in the catalyst formulation CaO and MgO replaced hydroxide additives at the expense of dissolution effects limiting catalyst stability. US 6,900,361 B2 describes a continuous three-step conversion process of lactose to glycols. The third step is the hydrogenolysis of an alditol-containing intermediate derived in the process to obtain glycols. Nickel-containing catalysts are suggested as particularly useful hydrogenation catalysts and US 5,814,112 and US 6,152,975 are given for reference. US 5,814,112 discloses catalysts comprising nickel and ruthenium, where the ruthenium is added to retard or reduce agglomeration or sintering of the nickel dispersed phase. Respective tests were performed with an aqueous phenol reaction mixture without a base additive. US 6,152,975 also discloses the addition of metals other than ruthenium to a nickel comprising catalyst to retard or reduce agglomeration or sintering. Again, tests were performed with an aqueous phenol reaction mixture without a base additive. Finally, the initial concentration of lactose in the aqueous feed of US 6,900,361 B2 is specified as 5 to 20 wt.-%, which is low and significantly diminishes the economics of said process.

EP 2 403 818 A1 discloses a process to obtain glycols (e.g. 1 ,2-PDO, EG, GLY) from sorbitol. The claimed catalysts comprise a polyacid promoted zirconium oxide support impregnated with at least one catalytically active metal, such as nickel. The polyacid promoter is specified to comprise at least one of chromium, molybdenum, tungsten, phosphorous, sulphur or organic polyacids. Examples of catalyst stability are not provided. An average sorbitol conversion of 71 % was achieved, severely limiting the overall yield of glycols. Thus, the state of the art is lacking catalysts for the production of glycols from sugar alcohols in high yields, which are sufficiently stable at the required operating conditions.

Despite the large number of catalysts which have been developed for the preparation of diols and a triols, each having two or three carbon atoms from sugars and a sugar alcohols, there still remains the need for yet more effective catalysts, which can be used at industrial scale overcoming the stability limitations. In particular, there remains the need for catalysts, which are stable in water at high temperatures, for example at temperatures above 100 °C and in particular in the presence of an acid or a base, thus allowing for a highly efficient process for the preparation of diols and a triols, each having two or three carbon atoms from sugars and a sugar alcohols.

It was therefore a further object of the present invention to provide a process for preparing one or more of a diol and a triol, each having two or three carbon atoms, which is not limited by a lack of catalyst stability. This includes the selection of a catalyst, which is mechanically and chemically stable in aqueous solutions of sugars and sugar alcohols at high temperature, for example at temperatures above 100 °C. Preferably, the stability of said catalyst must remain high in the presence of an acid or a base additive during the hydrogenolysis reaction. In addition, the selected catalyst comprises hydrogenating metals, such as nickel and nickel and copper, to achieve high activity in the hydrogenolysis of sugars and sugar alcohols. This is required to achieve high levels of feedstock conversion and product yields. Additionally, it was surprisingly found that the selected catalyst compositions comprising high concentrations of hydrogenating metals, such as nickel and copper, and in particular, that 40 to 90 wt.-% of the catalyst consists of nickel, and/or of nickel and copper achieve high activity in the hydrogenolysis of sugars and sugar alcohols. Therefore, the present invention relates to a process for preparing one or more of a mono-alcohol, a diol and a triol, each having two or three carbon atoms, the process comprising

(i) providing a liquid aqueous feed stream comprising one or more of a sugar and a sugar alcohol, each having three, five or six carbon atoms;

(ii) feeding the liquid aqueous feed stream provided according to (i) into a reaction zone comprising a catalyst which comprises nickel, and subjecting the feed stream to reaction conditions in the reaction zone, obtaining a reaction mixture comprising the one or more of a mono-alcohol, a diol and a triol;

(iii) removing a liquid aqueous effluent stream comprising the one or more of a mono-alcohol, a diol and a triol from the reaction zone; wherein the catalyst comprises zirconium oxide, wherein from 5 to 60 wt.-% of the catalyst consist of zirconium oxide, calculated as Zr©2.

It is preferred that the catalyst further comprises metal oxides, wherein the metal of the metal oxides is preferably selected from the group consisting of Na, Mg, Al, Si, K, Ca, Ti, Mn, Co, Cu, Zn, Nb, Mo, La, Hf, and W, including combinations of two or more thereof, more preferably from the group consisting of Na, Mg, Al, Si, Ca, Ti, Mn, Co, Cu, La, and Hf, including combinations of two or more thereof, more preferably from the group consisting of Al, Si, Mn, Co and Cu, including combinations of two or more thereof, more preferably from the group consisting of Cu and Co, including combinations thereof, more preferably the metal of the metal oxides is Cu, wherein more preferably the catalyst further comprises metal oxides selected from the group consisting of CuO, CoO, CO2O3 and CO3O4 including mixtures thereof, more preferably the catalyst further comprises CuO.

It is preferred that the catalyst has a degree of crystallinity in the range of from 60 to 100 %, preferably from 80 to 100 %, more preferably from 90 to 100 %, based on the total catalyst, as determined from the powder X-ray diffraction pattern of the catalyst, preferably as determined from the powder X-ray diffraction pattern of the catalyst according to the following formula:

Degree of Crystallinity wherein corresponds to the signal area attributed to the crystalline sample components and A corresponds to the signal area attributed to X-ray amorphous sample components, more preferably as determined from the powder X-ray diffraction pattern of the catalyst according to Example 4-1.

It is preferred that the powder X-ray diffraction pattern of the catalyst shows signal peaks in the ranges of from 28 to 29° and from 31 to 32° 20 angle.

The signal peaks in the ranges of from 28 to 29° and from 31 to 32° 20 angle are indicative of crystalline ZrO₂ in the monoclinic crystalline phase. It is preferred that the difference between maximum signal intensity and baseline signal intensity in the ranges of from 28 to 29° and from 31 to 32° 20 angle is greater than the difference between maximum signal intensity and baseline signal intensity in the range of from 29.5 to 31 ° 20 angle. It is preferred that the difference between maximum signal intensity and baseline signal intensity in the range of from 28 to 29° 20 angle is at least three times higher than the difference between maximum signal intensity and baseline signal intensity in the range of from 29.5 to 31 ° 20 angle. It is preferred that the difference between maximum signal intensity and baseline signal intensity in the range of from 28 to 29° 20 angle is at least six times higher than the difference between maximum signal intensity and baseline signal intensity in the range of from 29.5 to 31 ° 20 angle.

It is preferred that the catalyst comprises a monoclinic crystalline phase comprising zirconium oxide and optionally a tetragonal crystalline phase comprising zirconium oxide, preferably wherein the monoclinic crystalline phase comprises zirconium oxide in an amount of from 5 to 100 wt.-% and the tetragonal crystalline phase comprises zirconium oxide in an amount of from 0 to 20 wt.- %, based on 100 wt.-% of all crystalline phases in the catalyst, as determined from the powder X-ray diffraction pattern of the catalyst, preferably as determined from the powder X-ray diffraction pattern of the catalyst according to Example 4-1 .

It is preferred that the monoclinic crystalline phase comprises zirconium oxide in an amount of from 10 to 80 wt.-% and the tetragonal crystalline phase comprises zirconium oxide in an amount of from 0 to 10 wt.-%, based on 100 wt.-% of all crystalline phases in the catalyst, as determined from the powderX-ray diffraction pattern of the catalyst, preferably as determined from the powder X-ray diffraction pattern of the catalyst according to Example 4-1 . It is preferred that the monoclinic crystalline phase comprises zirconium oxide in an amount of from 25 to 70 wt.-% and the tetragonal crystalline phase comprises zirconium oxide in an amount of from 0 to 5 wt.-%, based on 100 wt.-% of all crystalline phases in the catalyst, as determined from the powder X-ray diffraction pattern of the catalyst, preferably as determined from the powder X-ray diffraction pattern of the catalyst according to Example 4-1 . It is preferred that the monoclinic crystalline phase comprises zirconium oxide in an amount of from 30 to 60 wt.-% and the tetragonal crystalline phase comprises zirconium oxide in an amount of from 0 to 5 wt.-%, based on 100 wt.-% of all crystalline phases in the catalyst, as determined from the powder X-ray diffraction pattern of the catalyst, preferably as determined from the powder X-ray diffraction pattern of the catalyst according to Example 4-1 .

It is preferred that from 40 to 90 wt.-% of the catalyst consists of nickel, preferably from 45 to 85 wt.-%, more preferably from 50 to 80 wt.-%, calculated as NiO.

It is preferred that from 40 to 90 wt.-% of the catalyst consists of nickel and copper, preferably from 60 to 85 wt.-%, calculated as NiO and CuO.

It is preferred that the catalyst contains substantially no aluminum oxide, preferably substantially no AI2O3. It is preferred that from 40 to 60 wt.-% of the catalyst consists of nickel, calculated as NiO, from 10 to 30 wt.-% of the catalyst consists of copper, calculated as CuO, and from 20 to 40 wt.-% of the catalyst consists of zirconium oxide, calculated as ZrC>2.

It is preferred that the catalyst contains substantially no CrOs and/or C^Os, preferably substantially no CrOs and C^Os.

It is preferred that the catalyst is in the form of a molding and/or in powder form, preferably in the form of a molding, more preferably in the form of extrudates and/or tablets and more preferably in the form of cylindrical tablets.

In the case where the catalyst is in the form of cylindrical tablets, it is preferred that the cylindrical tablets have a diameter x height in the range of from 1 x 1 to 10 x 10 mm, preferably of from 1 .5 x 1 .5 to 7 x 7 mm, more preferably of from 2.0 x 2.0 to 6 x 6 mm.

It is preferred that the sugar having three carbon atoms is glyceraldehyde.

It is preferred that the one or more of the sugar having five carbon atoms is selected from the group consisting of ribose, arabinose, xylose, and lyxose, including combinations of two or more thereof.

It is preferred that the one or more of the sugar having six carbon atoms is preferably selected from the group consisting of glucose, galactose, maltose, lactose, sucrose, allose, altrose, mannose, gulose, idose, talose, including combinations of two or more thereof.

It is preferred that the sugar alcohol having three carbon atoms is glycerol.

It is preferred that the one or more of the sugar alcohol having five carbon atoms is selected from the group consisting of arabitol, ribitol and xylitol, including combinations of two or more thereof, more preferably the sugar alcohol having six carbon atoms comprises xylitol.

It is preferred that the one or more of the sugar alcohol having six carbon atoms is selected from the group consisting of mannitol, iditol, galactitol and sorbitol including combinations of two or more thereof, more preferably the sugar alcohol having six carbon atoms comprises sorbitol.

It is preferred that the one or more of a mono-alcohol, a diol and a triol, each having two or three carbon atoms is selected from the group consisting of 1 ,2-propanediol, ethylene glycol, 1 ,3-pro- panediol, glycerol, 1 -propanol, 2-propanol and ethanol, including combinations of two or more thereof.

It is preferred that the one or more of a diol and a triol, each having two or three carbon atoms is selected from the group consisting of 1 ,2-propanediol, ethylene glycol and glycerol including combinations of two or more thereof. It is preferred that the diol having two carbon atoms comprises ethylene glycol.

It is preferred that the diol having three carbon atoms comprises 1 ,2-propanedioL

It is preferred that the triol having three carbon atoms comprises glycerol.

It is preferred that the liquid aqueous feed stream in (ii) comprises from 20 to 99 wt.-% of a sugar or a sugar alcohol, each having three, five or six carbon atoms, preferably from 25 to 60 wt.-%, more preferably from 25 to 40 wt.-%.

It is preferred that the liquid aqueous feed stream provided in (i) further comprises a solvent, preferably a solvent comprising a mono-alcohol, preferably the mono-alcohol is selected from the group consisting of methanol, ethanol, 1 -propanol, 2-propanol and 1 -butanol, more preferably the mono-alcohol is selected from the group consisting of methanol, ethanol and 1 -butanol, more preferably the mono-alcohol is ethanol.

It is preferred that the process relates to the preparation of one or more of a diol and a triol, each having two or three carbon atoms.

It is preferred that the liquid aqueous feed stream provided in (i) comprises one or more of a sugar and a sugar alcohol, each having five or six carbon atoms.

It is preferred that the liquid aqueous feed stream provided in (i) further comprises a compound selected from the group consisting of a base, a Lewis acid and a combination thereof, preferably the liquid aqueous feed stream provided in (i) further comprises a base.

In case where the liquid aqueous feed stream provided in (i) further comprises a base, it is preferred that in (i), the base is selected from the group consisting of metal hydroxide and metal carbonate, wherein the metal of the metal hydroxide and of the metal carbonate is preferably selected from the group consisting of Li, Na, K, Ca, and Mg, including combinations of two or more thereof, wherein more preferably the base comprises one or more metal hydroxide and meatal carbonate selected from the group consisting of LiOH, NaOH, Na2CC>3, KOH, K2CO3, Ca(OH)2, and Mg(OH)2, including mixtures of two or more thereof, preferably from the group consisting of NaOH, Na2CO3, KOH, K2CO3, Ca(OH)2 and Mg(OH)2, including combinations of two or more thereof, wherein more preferably the base comprises one or more metal hydroxide and metal carbonates selected from the group consisting of NaOH, Na2CO3, KOH and K2CO3, including combinations of two thereof, more preferably the base comprises, preferably is NaOH.

In case where the liquid aqueous feed stream provided in (i) further comprises a base, it is preferred that the liquid aqueous feed stream provided in (i) comprises from 0.1 to 8 wt.-% of the base, preferably from 0.3 to 7 wt.-%, more preferably from 4 to 6 wt.-%. In case where the liquid aqueous feed stream provided in (i) further comprises a Lewis acid, it is preferred that in (i), the Lewis acid is selected from the group consisting of metal polyacids, wherein the metal of the metal polyacid is preferably selected from the group consisting of Mo and W, including combinations of two or more thereof, wherein more preferably the Lewis acid comprise one or more metal polyacids selected from the group consisting of H2WO4 and (N H₄)₂MOO₂, including combinations thereof.

It is preferred that the reaction conditions according to (ii) comprise a reaction pressure in the range of from 40 to 250 bar, preferably from 60 to 200 bar and more preferably from 80 to 120 bar.

It is preferred that the reaction conditions according to (ii) comprise a temperature in the range of from 140 to 220 °C, preferably from 170 to 200 °C.

It is preferred that the reaction conditions according to (ii) comprise a liquid hourly space velocity in the range of from 0.1 to 5 IT¹, preferably of from 0.2 to 5 IT¹.

It is preferred that the liquid aqueous feed stream provided in (i) and fed into the reaction zone in (ii) further comprises H₂.

In case where the liquid aqueous feed stream provided in (i) and fed into the reaction zone in (ii) further comprises H₂, it is preferred that the liquid aqueous feed stream displays an H₂ : sugar or sugar alcohol molar ratio of H₂ to sugar or sugar alcohol in the range of from 1 to 8, preferably of from 1 .5 to 7, more preferably of from 1 .8 to 7.

It is preferred that the liquid aqueous effluent stream removed in (iii) comprises from 10 to 95 mol%C of the one or more of a mono-alcohol, a diol and a triol, each having two or three carbon atoms, preferably from 30 to 95 mol%C, more preferably from 40 to 95 mol%C, more preferably from 50 to 90 mol%C, based on 100 mol%C of the one or more of a sugar and a sugar alcohol, each having five or six carbon atoms, wherein mol%C is defined according to equation (I):

(i); wherein the subscript n refer to weight, molar mass and number of carbon atoms of 1 ,2-propane- diol, glycerol and ethylene glycol, respectively. The subscript a refers to weight, molar mass and number of carbon atoms of the one or more of a sugar and a sugar alcohol.

It is preferred that the liquid aqueous effluent stream removed in (iii) comprises from 10 to 95 mol%C of 1 ,2-propanediol, glycerol and ethylene glycol, preferably from 30 to 95 mol%C, more preferably from 40 to 95 mol%C, more preferably from 50 to 90 mol%C, based on 100 mol%C of the one or more of a sugar and a sugar alcohol, each having five or six carbon atoms, wherein mol%C is defined according to equation (II):

(ii); wherein the subscript 1-3 refer to weight, molar mass and number of carbon atoms of 1 ,2-pro- panediol, glycerol and ethylene glycol, respectively. The subscript a refers to weight, molar mass and number of carbon atoms of the one or more of a sugar and a sugar alcohol.

It is preferred that the liquid aqueous effluent stream removed in (iii) comprises from 10 to 95 mol%C of 1 ,2-propanediol, preferably from 20 to 95 mol%, more preferably from 30 to 95 mol%C, more preferably from 40 to 90 mol%C, based on 100 mol%C of the one or more of a sugar and a sugar alcohol, each having five or six carbon atoms, wherein mol%C is defined according to equation (III):

(HI); wherein the subscript a refers to weight, molar mass and number of carbon atoms of the one or more of a sugar and a sugar alcohol.

It is preferred that the process is a continuous process.

It is preferred that the process is operated in a trickle bed reactor.

The present invention further relates to a process for preparing a catalyst, preferably the catalyst for the process according to the present invention, the process comprising

(a) preparing a first mixture comprising zirconium oxide and water;

(b) preparing a second mixture comprising a nickel precursor selected from the group consisting of nickel nitrate, nickel halide, nickel acetate, nickel sulfate and, optionally, a copper precursor selected from the group of copper nitrate, copper halide, copper acetate, copper sulfate, copper amine complexes including combinations of two or more thereof and water;

(c) mixing the first mixture obtained in (a), the second mixture obtained in (b) and a precipitating agent, obtaining a slurry comprising a solid and water;

(d) removing the water from the slurry obtained in (c), obtaining a solid; (e) optionally, drying the solid obtained in (d) at a temperature in the range of 80 to 150 °C, obtaining a dried solid;

(f) calcining the solid obtained in (d), preferably the dried solid obtained in (e), at a temperature in the range of 300 to 700 °C, obtaining a catalyst comprising nickel oxide and zirconium oxide, wherein from 5 to 60 wt.-% of the catalyst consist of zirconium oxide, calculated as Zr©2, preferably the catalyst for the process of any of embodiments 1 to 41 .

In case the present invention relates to a process for preparing a catalyst, it is preferred that (a) comprises

(a.1 ) preparing a solution comprising a zirconium precursor selected from the group consisting of zirconium nitrate, zirconium halide, zirconyl halide, zirconium acetate, zirconium sulfate including combinations of two or more thereof and water;

(a.2) mixing the solution, prepared in (a.1) with a precipitation agent, obtaining a suspension;

(a.3) removing the water from the suspension obtained in (a.3), obtaining a solid;

(a.4) optionally, drying the solid obtained in (a.4) at a temperature in the range of 80 to 150 °C, obtaining a dried solid;

(a.5) calcining the solid obtained in (a.3), preferably the dried solid obtained in (a.4), at a temperature in the range of 400 to 800 °C, obtaining zirconium oxide.

It is preferred that the zirconium oxide has a degree of crystallinity in the range of from 60 to 100 %, preferably from 80 to 100 %, more preferably from 90 to 100 %, based on the total zirconium oxide, as determined from the powder X-ray diffraction pattern of the zirconium oxide, preferably as determined from the powder X-ray diffraction pattern of the zirconium oxide according to the following formula:

Degree of Crystallinity wherein corresponds to the signal area attributed to the crystalline sample components and A corresponds to the signal area attributed to X-ray amorphous sample components, more preferably as determined from the powder X-ray diffraction pattern of the zirconium oxide according to Example 1-1 .

It is preferred that the powder X-ray diffraction pattern of the zirconium oxide shows signal peaks in the ranges of from 28 to 29° and from 31 to 32° 20 angle, preferably the signal peaks are indicative of crystalline zirconium oxide in the monoclinic crystalline phase.

It is preferred that the difference between maximum signal intensity and baseline signal intensity in the ranges of from 28 to 29° and from 31 to 32° 20 angle is greater than the difference between maximum signal intensity and baseline signal intensity in the range of from 29.5 to 31 ° 20 angle. It is preferred that the difference between maximum signal intensity and baseline signal intensity in the range of from 28 to 29° 20 angle is at least two times higher than the difference between maximum signal intensity and baseline signal intensity in the range of from 29.5 to 31 ° 20 angle. It is preferred that the difference between maximum signal intensity and baseline signal intensity in the range of from 28 to 29° 20 angle is at least four times higher than the difference between maximum signal intensity and baseline signal intensity in the range of from 29.5 to 31 ° 20 angle.

It is preferred that zirconium oxide comprises a monoclinic crystalline phase and optionally a tetragonal crystalline phase, preferably wherein zirconium oxide comprises the monoclinic crystalline phase in an amount of from 50 to 100 wt.-% and the tetragonal crystalline phase in an amount of from 0 to 50 wt.-%, based on 100 wt.-% of all crystalline phases in zirconium oxide, as determined from the powder X-ray diffraction pattern of the zirconium oxide, preferably as determined from the powder X-ray diffraction pattern of the zirconium oxide according to Example 1-1. It is preferred that zirconium oxide comprises the monoclinic crystalline phase in an amount of from 70 to 100 wt.-% and the tetragonal crystalline phase in an amount of from 0 to 30 wt.-%, based on 100 wt.-% of all crystalline phases in zirconium oxide, as determined from the powder X-ray diffraction pattern of the zirconium oxide, preferably as determined from the powder X-ray diffraction pattern of the zirconium oxide according to Example 1-1. It is preferred that zirconium oxide comprises the monoclinic crystalline phase in an amount of from 80 to 100 wt.-% and the tetragonal crystalline phase in an amount of from 0 to 20 wt.-%, based on 100 wt.-% of all crystalline phases in zirconium oxide, as determined from the powder X-ray diffraction pattern of the zirconium oxide, preferably as determined from the powder X-ray diffraction pattern of the zirconium oxide according to Example 1-1. It is preferred that zirconium oxide comprises the monoclinic crystalline phase in an amount of from 90 to 100 wt.-% and the tetragonal crystalline phase in an amount of from 0 to 10 wt.-%, based on 100 wt.-% of all crystalline phases in zirconium oxide, as determined from the powder X-ray diffraction pattern of the zirconium oxide, preferably as determined from the powder X-ray diffraction pattern of the zirconium oxide according to Example 1- 1.

It is preferred that in (c) and/or in (a.3), the precipitating agent is selected from the group consisting of sodium carbonate, sodium hydroxide, ammonia and ammonium hydroxide, including combinations of two or more thereof.

In one embodiment, the catalyst is obtained through a sequence of precipitation, washing, drying and annealing steps. After the annealing step, the catalyst is in its oxidized state. The oxidized state is characterized in that the metals are present in the form of metal oxides or mixed metal oxides. Preferably, Ni is present as NiO, Zr is present as ZrO₂ and Cu is present as CuO. The catalyst composition is determined by analyzing the elemental content of the material in its oxidized state. The obtained values are converted into oxide contents using the molecular weights of the metals and the oxides.

In one embodiment, the catalyst is reduced prior to use or reduces during use. Accordingly, the active catalyst comprises nickel in its reduced state, preferably as nickel metal. In this case, the catalyst comprises nickel comprising an oxidation state of 0. In one embodiment, the catalyst reduction is incomplete. Accordingly, the active catalyst comprises nickel in its oxidized state, preferably as nickel oxide, preferably as NiO. In this case, the catalyst comprises nickel comprising an oxidation state selected from the group consisting of +l, -HI, +III and +IV, including combinations of two or more thereof, more preferably the catalyst comprises nickel comprising an oxidation state of -HI.

In one embodiment, in case where Cu is present in the catalyst, the catalyst is reduced prior to use or reduces during use. Accordingly, the active catalyst comprises copper in its reduced state, preferably as copper metal. In this case, the catalyst comprises copper comprising an oxidation state of 0.

It was a further an object of the present invention to provide a process for preparing one or more of a diol and a triol, each having two or three carbon atoms, which is not limited by a lack of catalyst stability. This includes the selection of a catalyst, which is mechanically and chemically stable in aqueous solutions of sugars and sugar alcohols at high temperature. Preferably, the stability of said catalyst must remain high in the presence of a base additive during the hydrogenolysis reaction. In addition, the selected catalyst comprises hydrogenating metals, such as nickel and nickel and copper, to achieve high activity in the hydrogenolysis of sugars and sugar alcohols. This is required to achieve high levels of feedstock conversion and product yields. Additionally, it was surprisingly found that the selected catalyst compositions comprising high concentrations of hydrogenating metals, such as nickel and copper, and in particular, that 40 to 90 wt.-% of the catalyst consists of nickel, and/or of nickel and copper achieve high activity in the hydrogenolysis of sugars and sugar alcohols.

Therefore, the present invention further relates to a process for preparing one or more of a diol and a triol, each having two or three carbon atoms, the process comprising

(i) providing a liquid aqueous feed stream comprising one or more of a sugar and a sugar alcohol, each having five or six carbon atoms;

(ii) feeding the liquid aqueous feed stream provided according to (i) into a reaction zone comprising a catalyst which comprises nickel, and subjecting the feed stream to reaction conditions in the reaction zone, obtaining a reaction mixture comprising the one or more of a diol and a triol;

(iii) removing a liquid aqueous effluent stream comprising one or more of a diol and a triol from the reaction zone; wherein the catalyst comprises zirconium oxide, wherein from 5 to 50 wt.-% of the catalyst consist of zirconium oxide, calculated as ZrC>2 and wherein from 0 to 15 wt.-% of the catalyst consist of aluminum oxide, calculated as AI2O3.

In one embodiment, the catalyst is obtained through a sequence of precipitation, washing, drying and annealing steps. After the annealing step, the catalyst is in its oxidized state. The oxidized state is characterized in that the metals are present in the form of metal oxides or mixed metal oxides. Preferably, Ni is present as NiO, Zr is present as Zr©2 and Al is present as AI2O3. The catalyst composition is determined by analyzing the elemental content of the material in its oxidized state. The obtained values are converted into oxide contents using the molecular weights of the metals and the oxides.

In one embodiment, the catalyst is reduced prior to use or reduces during use. Accordingly, the active catalyst comprises nickel in its reduced state, preferably as nickel metal. In this case, the catalyst comprises nickel comprising an oxidation state of 0.

In one embodiment, the catalyst reduction is incomplete. Accordingly, the active catalyst comprises nickel in its oxidized state, preferably as nickel oxide, preferably as NiO. In this case, the catalyst comprises nickel comprising an oxidation state selected from the group consisting of +l, -HI, +III and +IV, including combinations of two or more thereof, more preferably the catalyst comprises nickel comprising an oxidation state of +II.

In one embodiment, the catalyst contains substantially no aluminum oxide, preferably substantially no AI2O3. In the case where the catalyst contains substantially no aluminum oxide, preferably substantially no AI2O3, 0 wt.-% of the catalyst consist of aluminum oxide, calculated as AI2O3. In a further embodiment, the catalyst comprises aluminum oxide, wherein from 0.01 to 15 wt.-% of the catalyst consist of aluminum oxide, calculated as AI2O3.

It is preferred that the catalyst further comprises metal oxides, wherein the metal of the metal oxides is preferably selected from the group consisting of Na, Mg, Si, K, Ca, Ti, Mn, Co, Cu, Zn, Nb, Mo, La, Hf, and W, including combinations of two or more thereof, more preferably from the group consisting of Na, Mg, Si, Ca, Ti, Mn, Cu, Mo, La, Hf, and W, including combinations of two or more thereof, more preferably from the group consisting of Si, Ca, Cu, Mn, and Mo, including combinations of two or more thereof, more preferably from the group consisting of Si, and Mo, including combinations thereof, wherein more preferably the catalyst further comprises metal oxides selected from the group consisting of SiO2, CuO and MoO_x, wherein x is 1 to 3, including mixtures thereof.

It is preferred that from 0 to 10 wt.-% of the catalyst consist of aluminum oxide, preferably from 0 to 5.5 wt.-%, calculated as AI2O3.

It is preferred that from 40 to 90 wt.-% of the catalyst consists of nickel, preferably from 60 to 85 wt.-%, calculated as NiO.

It is preferred that from 0.1 to 5.5 wt.-% of the catalyst consists of aluminum oxide, preferably from 2 to 5.5 wt.-%, more preferably from 3 to 5 wt.-%, calculated as AI2O3.

It is preferred that from 65 to 75 wt.-% of the catalyst consists of nickel, calculated as NiO, from 5 to 7 wt.-% of the catalyst consists of zirconium oxide, calculated as ZrO2 and from 3 to 5 wt.-% of the catalyst consists of aluminum oxide, calculated as AI2O3. It is preferred that from 65 to 75 wt.-% of the catalyst consists of nickel, calculated as NiO, from 5 to 7 wt.-% of the catalyst consists of zirconium oxide, calculated as ZrC>2, from 3 to 5 wt.-% of the catalyst consists of aluminum oxide, calculated as AI2O3, from 15 to 25 wt.-% of the catalyst consists of silicon oxide, calculated as SiC>2.

In one embodiment, the catalyst comprises nickel and copper. In the case where the catalyst comprises nickel and copper, it is preferred that from 40 to 90 wt.-% of the catalyst consists of nickel and copper, preferably from 60 to 85 wt.-%, calculated as NiO and CuO.

In one embodiment, the catalyst is obtained through a sequence of precipitation, washing, drying and annealing steps. After the annealing step, the catalyst is in its oxidized state. The oxidized state is characterized in that the metals are present in the form of metal oxides or mixed metal oxides. Preferably, Ni is present as NiO, Cu is present as CuO, Zr is present as ZrO2 and Mo is present as MoOs. The catalyst composition is determined by analyzing the elemental content of the material in its oxidized state. The obtained values are converted into oxide contents using the molecular weights of the metals and the oxides.

In one embodiment, the catalyst is reduced prior to use or reduces during use. Accordingly, the active catalyst comprises nickel and copper in its reduced state, preferably as nickel metal and copper metal. In this case, the catalyst comprises nickel and copper comprising an oxidation state of O.

In one embodiment, the catalyst reduction is incomplete. Accordingly, the active catalyst comprises nickel and copper in its oxidized state, preferably as nickel oxide and copper oxide, preferably as NiO and CuO. In this case, the catalyst comprises nickel and copper comprising an oxidation state selected from the group consisting of +l, -HI, +III and +IV, including combinations of two or more thereof, more preferably the catalyst comprises nickel and copper comprising an oxidation state of -HI .

In the case where the catalyst comprises nickel and copper, it is preferred that the catalyst contains substantially no aluminum oxide, preferably substantially no AI2O3.

In the case where the catalyst comprises nickel and copper, it is preferred that from 40 to 60 wt.- % of the catalyst consists of nickel, calculated as NiO, from 10 to 30 wt.-% of the catalyst consists of copper, calculated as CuO, and from 20 to 40 wt.-% of the catalyst consists of zirconium oxide, calculated as ZrO2.

In the case where the catalyst comprises nickel and copper, it is preferred that from 40 to 60 wt.- % of the catalyst consist of nickel, calculated as NiO, from 10 to 30 wt.-% of the catalyst consists of copper, calculated as CuO, from 20 to 40 wt.-% of the catalyst consists of zirconium oxide, calculated as ZrO2, and from 0.1 to 5 wt.-% of the catalyst consists of molybdenum oxide, calculated as MoOs. It is preferred that zirconium oxide comprises one or more crystalline phases and/or is amorphous, wherein the one or more crystalline phases of zirconium oxide are selected from the group consisting of the monoclinic, tetragonal, and cubic phases of zirconium oxide, including mixtures of two or three thereof.

In the case where the catalyst is in the form of cylindrical tablets, it is preferred that the cylindrical tablets have a diameter x height in the range of from 1 x 1 to 10 x 10 mm, preferably of from 2 x 2 to 7 x 7 mm, more preferably of from 2.5 x 2.5 to 6 x 6 mm.

It is preferred that the one or more of a diol and a triol, each having two or three carbon atoms is selected from the group consisting of 1 ,2-propanediol, ethylene glycol, 1 ,3-propanediol, and glycerol, including combinations of two or more thereof, preferably the one or more of a diol and a triol, each having two or three carbon atoms is selected from the group consisting of 1 ,2-propane- diol, ethylene glycol and glycerol including combinations of two or more thereof.

It is preferred that the diol having two carbon atoms comprises ethylene glycol.

It is preferred that the triol having three carbon atoms comprises glycerol. It is preferred that the liquid aqueous feed stream prepared in (ii) comprises from 20 to 60 wt.-% of a sugar or a sugar alcohol, each having five or six carbon atoms, preferably from 25 to 50 wt.- %, more preferably from 25 to 40 wt.-%.

It is preferred that the liquid aqueous feed stream provided in (i) further comprises a solvent, preferably a solvent comprising a monohydric alcohol, more preferably the monohydric alcohol is selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol and 1 -butanol.

It is preferred that the liquid aqueous feed stream provided in (i) further comprises a compound selected from the group consisting of a base, a Lewis acid and a combination thereof, preferably a base.

In case where the liquid aqueous feed stream provided in (i) further comprises a base, it is preferred that the base is selected from the group consisting of metal hydroxides, wherein the metal of the metal hydroxide is preferably selected from the group consisting of Li, Na, K, Ca, and Mg, including combinations of two or more thereof, wherein more preferably the base comprise one or more metal hydroxides selected from the group consisting of LiOH, NaOH, KOH, Ca(OH)2, and Mg(OH)2, including mixtures of two or more thereof, preferably from the group consisting of NaOH, KOH, Ca(OH)2, and Mg(OH)2, including combinations of two or more thereof, wherein more preferably the base comprise one or more metal hydroxides selected from the group consisting of NaOH and KOH, including combinations of two thereof, more preferably the base comprises NaOH.

In case where the liquid aqueous feed stream provided in (i) further comprises a base, it is preferred that the liquid aqueous feed stream provided in (i) comprises from 0.1 to 8 wt.-% of the base, preferably from 0.3 to 7 wt.-%, more preferably from 4 to 6 wt.-%.

In case where the liquid aqueous feed stream provided in (i) further comprises an acid, it is preferred that the acid is selected from the group consisting of phosphoric acid and sulfuric acid, including combinations thereof.

In case where the liquid aqueous feed stream provided in (i) further comprises a Lewis acid, it is preferred that the Lewis acid is selected from the group consisting of metal polyacids, wherein the metal of the metal polyacid is preferably selected from the group consisting of Mo and W, including combinations of two or more thereof, wherein more preferably the Lewis acid comprise one or more metal polyacids selected from the group consisting of H2WO4 and (NH4)2MoO2, including combinations thereof.

It is preferred that the reaction conditions according to (ii) comprise a reaction pressure in the range of from 40 to 170 bar, preferably from 60 to 150 bar and more preferably from 80 to 120 bar. It is preferred that the reaction conditions according to (ii) comprise a temperature in the range of from 140 to 210 °C, preferably from 170 to 200 °C.

It is preferred that the liquid aqueous feed stream provided in (i) and fed into the reaction zone in (ii) further comprises H2.

In case where the liquid aqueous feed stream provided in (i) and fed into the reaction zone in (ii) further comprises H2, it is preferred that the liquid aqueous feed stream displays an H2 : sugar or sugar alcohol molar ratio of H2 to sugar or sugar alcohol in the range of from 1 to 8, preferably of from 1 .5 to 7, more preferably of from 1 .8 to 7.

It is preferred that the liquid aqueous effluent stream removed in (iii) comprises from 10 to 95 mol%C of the one or more of a diol and a triol, each having two or three carbon atoms, preferably from 15 to 95 mol%C, more preferably from 20 to 85 mol%C, more preferably from 25 to 80 mol%C, based on 100 mol%C of the one or more of a sugar and a sugar alcohol, each having five or six carbon atoms, wherein mol%C is defined according to equation (I):

(i); wherein, the subscript n refers to weight, molar mass and number of carbon atoms of the one diol or more of a diol and a triol . The subscript a refers to weight, molar mass and number of carbon atoms of the one or more of a sugar and a sugar alcohol.

It is preferred that the liquid aqueous effluent stream removed in (iii) comprises from 10 to 95 mol%C of 1 ,2-propanediol, glycerol and ethylene glycol, preferably from 15 to 90 mol%C, more preferably from 20 to 85 mol%C, more preferably from 25 to 80 mol%C, based on 100 mol%C of the one or more of a sugar and a sugar alcohol, each having five or six carbon atoms, wherein mol%C is defined according to equation (II): wherein, the subscript 1-3 refer to weight, molar mass and number of carbon atoms of 1 ,2-pro- panediol, glycerol and ethylene glycol, respectively. The subscript a refers to weight, molar mass and number of carbon atoms of the one or more of a sugar and a sugar alcohol.

It is preferred that the liquid aqueous effluent stream removed in (iii) comprises from 10 to 80 mol%C of 1 ,2-propanediol, preferably from 15 to 75 mol%, more preferably from 20 to 70 mol%C, more preferably from 25 to 65 mol%C, based on 100 mol%C of the one or more of a sugar and a sugar alcohol, each having five or six carbon atoms, wherein mol%C is defined according to equation (III):

It is preferred that the process is a continuous process.

It is preferred that the process is operated in a trickle bed reactor.

The present invention is further illustrated by the following set of embodiments and combinations of embodiments resulting from the dependencies and back-references as indicated. In particular, it is noted that in each instance where a range of embodiments is mentioned, for example in the context of a term such as "The ... of any one of embodiments 1 to 4", every embodiment in this range is meant to be explicitly disclosed for the skilled person, i.e. the wording of this term is to be understood by the skilled person as being synonymous to "The ... of any one of embodiments 1 , 2, 3, and 4". Further, it is explicitly noted that the following set of embodiments is not the set of claims determining the extent of protection, but represents a suitably structured part of the description directed to general and preferred aspects of the present invention.

1 . A process for preparing one or more of a mono-alcohol, a diol and a triol, each having two or three carbon atoms, the process comprising

(iii) removing a liquid aqueous effluent stream comprising the one or more of a monoalcohol, a diol and a triol from the reaction zone; wherein the catalyst comprises zirconium oxide, wherein from 5 to 60 wt.-% of the catalyst consist of zirconium oxide, calculated as Zr©2.

2. The process of embodiment 1 , wherein the catalyst further comprises metal oxides, wherein the metal of the metal oxides is preferably selected from the group consisting of Na, Mg, Al, Si, K, Ca, Ti, Mn, Co, Cu, Zn, Nb, Mo, La, Hf, and W, including combinations of two or more thereof, more preferably from the group consisting of Na, Mg, Al, Si, Ca, Ti, Mn, Co, Cu, La, and Hf, including combinations of two or more thereof, more preferably from the group consisting of Al, Si, Mn, Co and Cu, including combinations of two or more thereof, more preferably from the group consisting of Cu and Co, including combinations thereof, more preferably the metal of the metal oxides is Cu, wherein more preferably the catalyst further comprises metal oxides selected from the group consisting of CuO, CoO, CO2O3 and CO3O4 including mixtures thereof, more preferably the catalyst further comprises CuO.

3. The process of embodiment 1 or 2, wherein the catalyst has a degree of crystallinity in the range of from 60 to 100 %, preferably from 80 to 100 %, more preferably from 90 to 100 %, based on the total catalyst, as determined from the powder X-ray diffraction pattern of the catalyst, preferably as determined from the powder X-ray diffraction pattern of the catalyst according to the following formula:

Degree of Crystallinity wherein corresponds to the signal area attributed to the crystalline sample components and A corresponds to the signal area attributed to X-ray amorphous sample components, more preferably as determined from the powder X-ray diffraction pattern of the catalyst according to Example 4-1 .

4. The process of any of embodiments 1 to 3, wherein the powder X-ray diffraction pattern of the catalyst shows signal peaks in the ranges of from 28 to 29° and from 31 to 32° 20 angle, preferably the difference between maximum signal intensity and baseline signal intensity in the ranges of from 28 to 29° and from 31 to 32° 20 angle is greater than the difference between maximum signal intensity and baseline signal intensity in the range of from 29.5 to 31⁰ 20 angle, more preferably the difference between maximum signal intensity and baseline signal intensity in the range of from 28 to 29° 20 angle is at least three times higher than the difference between maximum signal intensity and baseline signal intensity in the range of from 29.5 to 31 ° 20 angle, more preferably the difference between maximum signal intensity and baseline signal intensity in the range of from 28 to 29° 20 angle is at least six times higher than the difference between maximum signal intensity and baseline signal intensity in the range of from 29.5 to 31⁰ 20 angle.

5. The process of any of embodiments 1 to 4, wherein the catalyst comprises a monoclinic crystalline phase comprising zirconium oxide and optionally a tetragonal crystalline phase comprising zirconium oxide, preferably wherein the monoclinic crystalline phase comprises zirconium oxide in an amount of from 5 to 100 wt.-% and the tetragonal crystalline phase comprises zirconium oxide in an amount of from 0 to 20 wt.-%, based on 100 wt.-% of all crystalline phases in the catalyst, as determined from the powder X-ray diffraction pattern of the catalyst, preferably as determined from the powder X-ray diffraction pattern of the catalyst according to Example 4-1 , preferably wherein the monoclinic crystalline phase comprises zirconium oxide in an amount of from 10 to 80 wt.-% and the tetragonal crystalline phase comprises zirconium oxide in an amount of from 0 to 10 wt.-%, based on 100 wt.-% of all crystalline phases in the catalyst, as determined from the powder X-ray diffraction pattern of the catalyst, preferably as determined from the powder X-ray diffraction pattern of the catalyst according to Example 4-1 , more preferably wherein the monoclinic crystalline phase comprises zirconium oxide in an amount of from 25 to 70 wt.-% and the tetragonal crystalline phase comprises zirconium oxide in an amount of from 0 to 5 wt.-%, based on 100 wt.-% of all crystalline phases in the catalyst, as determined from the powder X-ray diffraction pattern of the catalyst, preferably as determined from the powder X-ray diffraction pattern of the catalyst according to Example 4-1 , more preferably wherein the monoclinic crystalline phase comprises zirconium oxide in an amount of from 30 to 60 wt.-% and the tetragonal crystalline phase comprises zirconium oxide in an amount of from 0 to 5 wt.-%, based on 100 wt.-% of all crystalline phases in the catalyst, as determined from the powder X-ray diffraction pattern of the catalyst, preferably as determined from the powder X-ray diffraction pattern of the catalyst according to Example 4-1 .

6. The process of any of embodiments 1 to 5, wherein from 40 to 90 wt.-% of the catalyst consists of nickel, preferably from 45 to 85 wt.-%, more preferably from 50 to 80 wt.-%, calculated as NiO.

7. The process of any of embodiments 1 to 6, wherein from 40 to 90 wt.-% of the catalyst consists of nickel and copper, preferably from 60 to 85 wt.-%, calculated as NiO and CuO.

8. The process of any of embodiments 1 to 7, wherein the catalyst contains substantially no aluminum oxide, preferably substantially no AI2O3.

9. The process of any of embodiments 1 to 8, wherein from 40 to 60 wt.-% of the catalyst consists of nickel, calculated as NiO, from 10 to 30 wt.-% of the catalyst consists of copper, calculated as CuO, and from 20 to 40 wt.-% of the catalyst consists of zirconium oxide, calculated as ZrO₂.

10. The process of any of embodiments 1 to 9, wherein the catalyst contains substantially no CrOs and/or Cr₂O3, preferably substantially no CrOs and Cr₂O3.

11 . The process of any of embodiments 1 to 10, wherein the catalyst is in the form of a molding and/or in powder form, preferably in the form of a molding, more preferably in the form of extrudates and/or tablets and more preferably in the form of cylindrical tablets. 12. The process of embodiment 11 , wherein the cylindrical tablets have a diameter x height in the range of from 1 x 1 to 10 x 10 mm, preferably of from 1.5 x 1.5 to 7 x 7 mm, more preferably of from 2.0 x 2.0 to 6 x 6 mm.

13. The process of any of embodiments 1 to 12, wherein the sugar having three carbon atoms is glyceraldehyde.

14. The process of any of embodiments 1 to 13, wherein the one or more of the sugar having five carbon atoms is selected from the group consisting of ribose, arabinose, xylose, and lyxose, including combinations of two or more thereof.

15. The process of any of embodiments 1 to 14, wherein the one or more of the sugar having six carbon atoms is preferably selected from the group consisting of glucose, galactose, maltose, lactose, sucrose, allose, altrose, mannose, gulose, idose, talose, including combinations of two or more thereof.

16. The process of any of embodiments 1 to 15, wherein the sugar alcohol having three carbon atoms is glycerol.

17. The process of any of embodiments 1 to 16, wherein the one or more of the sugar alcohol having five carbon atoms is selected from the group consisting of arabitol, ribitol and xylitol, including combinations of two or more thereof, more preferably the sugar alcohol having six carbon atoms comprises xylitol.

18. The process of any of embodiments 1 to 17, wherein the one or more of the sugar alcohol having six carbon atoms is selected from the group consisting of mannitol, iditol, galactitol and sorbitol including combinations of two or more thereof, more preferably the sugar alcohol having six carbon atoms comprises sorbitol.

19. The process of any of embodiments 1 to 18, wherein the one or more of a mono-alcohol, a diol and a triol, each having two or three carbon atoms is selected from the group consisting of 1 ,2-propanediol, ethylene glycol, 1 ,3-propanediol, glycerol, 1 -propanol, 2-propanol and ethanol, including combinations of two or more thereof.

20. The process of any of embodiments 1 to 19, wherein the one or more of a diol and a triol, each having two or three carbon atoms is selected from the group consisting of 1 ,2-propane- diol, ethylene glycol and glycerol including combinations of two or more thereof.

21 . The process of any of embodiments 1 to 20, wherein the diol having two carbon atoms comprises ethylene glycol. 22. The process of any of embodiments 1 to 21 , wherein the diol having three carbon atoms comprises 1 ,2-propanedioL

23. The process of any of embodiments 1 to 22, wherein the triol having three carbon atoms comprises glycerol.

24. The process of any of embodiments 1 to 23, wherein the liquid aqueous feed stream in (ii) comprises from 20 to 99 wt.-% of a sugar or a sugar alcohol, each having three, five or six carbon atoms, preferably from 25 to 60 wt.-%, more preferably from 25 to 40 wt.-%.

25. The process of any of embodiments 1 to 24, wherein the liquid aqueous feed stream provided in (i) further comprises a solvent, preferably a solvent comprising a mono-alcohol, preferably the mono-alcohol is selected from the group consisting of methanol, ethanol, 1 -propanol, 2- propanol and 1 -butanol, more preferably the mono-alcohol is selected from the group consisting of methanol, ethanol and 1 -butanol, more preferably the mono-alcohol is ethanol.

26. The process of any of embodiments 1 to 25, wherein the process relates to the preparation of one or more of a diol and a triol, each having two or three carbon atoms.

27. The process of any of embodiments 1 to 26, wherein the liquid aqueous feed stream provided in (i) comprises one or more of a sugar and a sugar alcohol, each having five or six carbon atoms.

28. The process of any of embodiments 1 to 27, wherein the liquid aqueous feed stream provided in (i) further comprises a compound selected from the group consisting of a base, a Lewis acid and a combination thereof, preferably the liquid aqueous feed stream provided in (i) further comprises a base.

29. The process of embodiment 28, wherein in (i), the base is selected from the group consisting of metal hydroxide and metal carbonate, wherein the metal of the metal hydroxide and of the metal carbonate is preferably selected from the group consisting of Li, Na, K, Ca, and Mg, including combinations of two or more thereof, wherein more preferably the base comprises one or more metal hydroxide and meatal carbonate selected from the group consisting of LiOH, NaOH, Na2CC>3, KOH, K2CO3, Ca(OH)2, and Mg(OH)2, including mixtures oftwo or more thereof, preferably from the group consisting of NaOH, Na2CO3, KOH, K2CO3, Ca(OH)2 and Mg(OH)2, including combinations of two or more thereof, wherein more preferably the base comprises one or more metal hydroxide and metal carbonates selected from the group consisting of NaOH, Na2CO3, KOH and K2CO3, including combinations of two thereof, more preferably the base comprises, preferably is NaOH.

30. The process of embodiment 28 or 29 wherein the liquid aqueous feed stream provided in (i) comprises from 0.1 to 8 wt.-% of the base, preferably from 0.3 to 7 wt.-%, more preferably from 4 to 6 wt.-%. 31 . The process of embodiment 28, wherein in (i), the Lewis acid is selected from the group consisting of metal polyacids, wherein the metal of the metal polyacid is preferably selected from the group consisting of Mo and W, including combinations of two or more thereof, wherein more preferably the Lewis acid comprise one or more metal polyacids selected from the group consisting of H2WO4 and (NH4)2MoO2, including combinations thereof.

32. The process of any of embodiments 1 to 31 , wherein the reaction conditions according to (ii) comprise a reaction pressure in the range of from 40 to 250 bar, preferably from 60 to 200 bar and more preferably from 80 to 120 bar.

33. The process of any of embodiments 1 to 32, wherein the reaction conditions according to (ii) comprise a temperature in the range of from 140 to 220 °C, preferably from 170 to 200 °C.

34. The process of any of embodiments 1 to 33 wherein the reaction conditions according to (ii) comprise a liquid hourly space velocity in the range of from 0.1 to 5 IT¹, preferably of from 0.2 to 5 IT¹.

35. The process of any of embodiments 1 to 34, wherein the liquid aqueous feed stream provided in (i) and fed into the reaction zone in (ii) further comprises H2.

36. The process of embodiment 35, wherein the liquid aqueous feed stream displays an H2 : sugar or sugar alcohol molar ratio of H2 to sugar or sugar alcohol in the range of from 1 to 8, preferably of from 1 .5 to 7, more preferably of from 1 .8 to 7.

37. The process of any of embodiments 1 to 36, wherein the liquid aqueous effluent stream removed in (iii) comprises from 10 to 95 mol%C of the one or more of a mono-alcohol, a diol and a triol, each having two or three carbon atoms, preferably from 30 to 95 mol%C, more preferably from 40 to 95 mol%C, more preferably from 50 to 90 mol%C, based on 100 mol%C of the one or more of a sugar and a sugar alcohol, each having five or six carbon atoms, wherein mol%C is defined according to equation (I):

(i); wherein the subscript n refer to weight, molar mass and number of carbon atoms of 1 ,2-pro- panediol, glycerol and ethylene glycol, respectively. The subscript a refers to weight, molar mass and number of carbon atoms of the one or more of a sugar and a sugar alcohol.

38. The process of any of embodiments 1 to 37, wherein the liquid aqueous effluent stream removed in (iii) comprises from 10 to 95 mol%C of 1 ,2-propanediol, glycerol and ethylene glycol, preferably from 30 to 95 mol%C, more preferably from 40 to 95 mol%C, more preferably from 50 to 90 mol%C, based on 100 mol%C of the one or more of a sugar and a sugar alcohol, each having five or six carbon atoms, wherein mol%C is defined according to equation (II):

(ii); wherein the subscript 1-3 refer to weight, molar mass and number of carbon atoms of 1 ,2- propanediol, glycerol and ethylene glycol, respectively. The subscript a refers to weight, molar mass and number of carbon atoms of the one or more of a sugar and a sugar alcohol. The process of any of embodiments 1 to 38, wherein the liquid aqueous effluent stream removed in (iii) comprises from 10 to 95 mol%C of 1 ,2-propanediol, preferably from 20 to 95 mol%, more preferably from 30 to 95 mol%C, more preferably from 40 to 90 mol%C, based on 100 mol%C of the one or more of a sugar and a sugar alcohol, each having five or six carbon atoms, wherein mol%C is defined according to equation (III):

(HI); wherein the subscript a refers to weight, molar mass and number of carbon atoms of the one or more of a sugar and a sugar alcohol. The process of any of embodiments 1 to 39, wherein the process is a continuous process. The process of any of embodiments 1 to 40, wherein the process is operated in a trickle bed reactor. A process for preparing a catalyst, preferably the catalyst for the process of any of embodiments 1 to 41 , the process comprising

(a) preparing a first mixture comprising zirconium oxide and water;

(c) mixing the first mixture obtained in (a), the second mixture obtained in (b) and a precipitating agent, obtaining a slurry comprising a solid and water; (d) removing the water from the slurry obtained in (c), obtaining a solid;

(e) optionally, drying the solid obtained in (d) at a temperature in the range of 80 to 150 °C, obtaining a dried solid;

(f) calcining the solid obtained in (d), preferably the dried solid obtained in (e), at a temperature in the range of 300 to 700 °C, obtaining a catalyst comprising nickel oxide and zirconium oxide, wherein from 5 to 60 wt.-% of the catalyst consist of zirconium oxide, calculated as Zr©2, preferably the catalyst for the process of any of embodiments 1 to 41.

43. The process of embodiment 42, wherein (a) comprises

(a.2) mixing the solution, prepared in (a.1 ) with a precipitation agent, obtaining a suspension;

44. The process of embodiment 42 or 43, wherein the zirconium oxide has a degree of crystallinity in the range of from 60 to 100 %, preferably from 80 to 100 %, more preferably from 90 to 100 %, based on the total zirconium oxide, as determined from the powder X-ray diffraction pattern of the zirconium oxide, preferably as determined from the powder X-ray diffraction pattern of the zirconium oxide according to the following formula:

Degree of Crystallinity wherein corresponds to the signal area attributed to the crystalline sample components and A corresponds to the signal area attributed to X-ray amorphous sample components, more preferably as determined from the powder X-ray diffraction pattern of the zirconium oxide according to Example 1-1.

45. The process of any of the embodiments 42 to 44, wherein the powder X-ray diffraction pattern of the zirconium oxide shows signal peaks in the range of from 28 to 29° and from 31 to 32° 2 0 angle, preferably the signal peaks are indicative of crystalline zirconium oxide in the monoclinic crystalline phase, more preferably the difference between maximum signal intensity and baseline signal intensity in the ranges of from 28 to 29° and from 31 to 32° 20 angle is greater than the difference between maximum signal intensity and baseline signal intensity in the range of from 29.5 to 31 ° 20 angle, more preferably the difference between maximum signal intensity and baseline signal intensity in the range of from 28 to 29° 20 angle is at least two times higher than the difference between maximum signal intensity and baseline signal intensity in the range of from 29.5 to 31 ° 20 angle, more preferably the difference between maximum signal intensity and baseline signal intensity in the range of from 28 to 29° 20 angle is at least four times higher than the difference between maximum signal intensity and baseline signal intensity in the range of from 29.5 to 31 ° 20 angle.

46. The process of any of the embodiments 42 to 45, wherein zirconium oxide comprises a monoclinic crystalline phase and optionally a tetragonal crystalline phase, preferably wherein zirconium oxide comprises the monoclinic crystalline phase in an amount of from 50 to 100 wt.- % and the tetragonal crystalline phase in an amount of from 0 to 50 wt.-%, based on 100 wt.- % of all crystalline phases in zirconium oxide, as determined from the powder X-ray diffraction pattern of the zirconium oxide, preferably as determined from the powder X-ray diffraction pattern of the zirconium oxide according to Example 1-1 , preferably wherein zirconium oxide comprises the monoclinic crystalline phase in an amount of from 70 to 100 wt.-% and the tetragonal crystalline phase in an amount of from 0 to 30 wt.-%, based on 100 wt.-% of all crystalline phases in zirconium oxide, as determined from the powder X-ray diffraction pattern of the zirconium oxide, preferably as determined from the powder X-ray diffraction pattern of the zirconium oxide according to Example 1-1 , more preferably wherein zirconium oxide comprises the monoclinic crystalline phase in an amount of from 80 to 100 wt.-% and the tetragonal crystalline phase in an amount of from 0 to 20 wt.-%, based on 100 wt.-% of all crystalline phases in zirconium oxide, as determined from the powder X-ray diffraction pattern of the zirconium oxide, preferably as determined from the powder X-ray diffraction pattern of the zirconium oxide according to Example 1-1 , more preferably wherein zirconium oxide comprises the monoclinic crystalline phase in an amount of from 90 to 100 wt.-% and the tetragonal crystalline phase in an amount of from 0 to 10 wt.-%, based on 100 wt.-% of all crystalline phases in zirconium oxide, as determined from the powder X-ray diffraction pattern of the zirconium oxide, preferably as determined from the powder X-ray diffraction pattern of the zirconium oxide according to Example 1-1.

47. The process of any of the embodiments 42 to 46, wherein in (c) and/or in (a.3), the precipitating agent is selected from the group consisting of sodium carbonate, sodium hydroxide, ammonia and ammonium hydroxide, including combinations of two or more thereof.

The present invention is further illustrated by the following second set of embodiments and combinations of embodiments resulting from the dependencies and back-references as indicated. The second set of embodiments may be combined with any one of the first set of embodiments above and the third set of embodiments below. In particular, it is noted that in each instance where a range of embodiments is mentioned, for example in the context of a term such as "The ... of any one of embodiments T to 4’ ", every embodiment in this range is meant to be explicitly disclosed for the skilled person, i.e. the wording of this term is to be understood by the skilled person as being synonymous to "The ... of any one of embodiments T, 2’, 3’, and 4’ ". Further, it is explicitly noted that the following set of embodiments is not the set of claims determining the extent of protection, but represents a suitably structured part of the description directed to general and preferred aspects of the present invention.

T. A process for preparing one or more of a diol and a triol, each having two or three carbon atoms, the process comprising

2’. The process of embodiment T, wherein the catalyst further comprises metal oxides, wherein the metal of the metal oxides is preferably selected from the group consisting of Na, Mg, Si, K, Ca, Ti, Mn, Co, Cu, Zn, Nb, Mo, La, Hf, and W, including combinations of two or more thereof, more preferably from the group consisting of Na, Mg, Si, Ca, Ti, Mn, Cu, Mo, La, Hf, and W, including combinations of two or more thereof, more preferably from the group consisting of Si, Ca, Mn, Cu and Mo, including combinations of two or more thereof, more preferably from the group consisting of Si, Cu and Mo, including combinations thereof, wherein more preferably the catalyst further comprises metal oxides selected from the group consisting of SiO2, CuO and MoO_x, wherein x is 1 to 3, including mixtures thereof.

3’. The process of embodiment T or 2’, wherein from 0 to 10 wt.-% of the catalyst consist of aluminum oxide, preferably from 0 to 5.5 wt.-%, calculated as AI2O3.

4’. The process of any of embodiments 1 ’ to 3’, wherein from 40 to 90 wt.-% of the catalyst consists of nickel, preferably from 60 to 85 wt.-%, calculated as NiO.

5’. The process of any of embodiments T to 4’, wherein from 0.1 to 5.5 wt.-% of the catalyst consists of aluminum oxide, preferably from 2 to 5.5 wt.-%, more preferably from 3 to 5 wt.- %, calculated as AI2O3.

6’. The process of any of embodiments 1 ’ to 5’, wherein from 65 to 75 wt.-% of the catalyst consists of nickel, calculated as NiO, from 5 to 7 wt.-% of the catalyst consists of zirconium oxide, calculated as Zr©2 and from 3 to 5 wt.-% of the catalyst consists of aluminum oxide, calculated as AI2O3. T. The process of any of embodiments 1 ’ to 6’, wherein from 65 to 75 wt.-% of the catalyst consists of nickel, calculated as NiO, from 5 to 7 wt.-% of the catalyst consists of zirconium oxide, calculated as ZrC>2, from 3 to 5 wt.-% of the catalyst consists of aluminum oxide, calculated as AI2O3 and from 15 to 25 wt.-% of the catalyst consists of silicon oxide, calculated as SiC>2

8’. The process of any of embodiments 1 ’ to 4’, wherein from 40 to 90 wt.-% of the catalyst consists of nickel and copper, preferably from 60 to 85 wt.-%, calculated as NiO and CuO.

9’. The process of any of embodiments T to 4’ or 8’, wherein the catalyst contains substantially no aluminum oxide, preferably substantially no AI2O3.

10’. The process of any of embodiments T to 4’, 8’ or 9’, wherein from 40 to 60 wt.-% of the catalyst consists of nickel, calculated as NiO, from 10 to 30 wt.-% of the catalyst consists of copper, calculated as CuO, and from 20 to 40 wt.-% of the catalyst consists of zirconium oxide, calculated as ZrO2.

11 ’.The process of any of embodiments 1 ’ to 4’, 8’, 9’ or 10’ wherein from 40 to 60 wt.-% of the catalyst consist of nickel, calculated as NiO, from 10 to 30 wt.-% of the catalyst consists of copper, calculated as CuO, from 20 to 40 wt.-% of the catalyst consists of zirconium oxide, calculated as ZrO2, and from 0.1 to 5 wt.-% of the catalyst consists of molybdenum oxide, calculated as MoOs.

12’. The process of any of embodiments T to 1 T, wherein zirconium oxide comprises one or more crystalline phases and/or is amorphous, wherein the one or more crystalline phases of zirconium oxide are selected from the group consisting of the monoclinic, tetragonal, and cubic phases of zirconium oxide, including mixtures of two or three thereof.

13’. The process of any of embodiments T to 12’, wherein the catalyst contains substantially no CrOs and/or CT2O3, preferably substantially no CrOs and CT2O3.

14’. The process of any of embodiments T to 13’, wherein the catalyst is in the form of a molding and/or in powder form, preferably in the form of a molding, more preferably in the form of extrudates and/or tablets and more preferably in the form of cylindrical tablets.

15’. The process of embodiment 14’, wherein the cylindrical tablets have a diameter x height in the range of from 1 x 1 to 10 x 10 mm, preferably of from 2 x 2 to 7 x 7 mm, more preferably of from 2.5 x 2.5 to 6 x 6 mm.

16’. The process of any of embodiments T to 15’, wherein the one or more of the sugar having five carbon atoms is selected from the group consisting of ribose, arabinose, xylose, and lyx- ose, including combinations of two or more thereof. ’. The process of any of embodiments T to 16’, wherein the one or more of the sugar having six carbon atoms is preferably selected from the group consisting of glucose, galactose, maltose, lactose, sucrose, allose, altrose, mannose, gulose, idose, talose, including combinations of two or more thereof. ’. The process of any of embodiments T to 17’, wherein the one or more of the sugar alcohol having five carbon atoms is selected from the group consisting of arabitol, ribitol and xylitol, including combinations of two or more thereof, more preferably the sugar alcohol having six carbon atoms comprises xylitol. ’. The process of any of embodiments T to 18’, wherein the one or more of the sugar alcohol having six carbon atoms is selected from the group consisting of mannitol, iditol, galactitol and sorbitol including combinations of two or more thereof, more preferably the sugar alcohol having six carbon atoms comprises sorbitol. ’. The process of any of embodiments T to 19’, wherein the one or more of a diol and a triol, each having two or three carbon atoms is selected from the group consisting of 1 ,2-propane- diol, ethylene glycol, 1 ,3-propanediol, and glycerol, including combinations of two or more thereof, preferably the one or more of a diol and a triol, each having two or three carbon atoms is selected from the group consisting of 1 ,2-propanediol, ethylene glycol and glycerol including combinations of two or more thereof. ’.The process of any of embodiments 1 ’ to 20’, wherein the diol having two carbon atoms comprises ethylene glycol. ’. The process of any of embodiments T to 2T, wherein the diol having three carbon atoms comprises 1 ,2-propanediol ’. The process of any of embodiments T to 22’, wherein the triol having three carbon atoms comprises glycerol. ’. The process of any of embodiments T to 23’, wherein the liquid aqueous feed stream prepared in (ii) comprises from 20 to 60 wt.-% of a sugar or a sugar alcohol, each having five or six carbon atoms, preferably from 25 to 50 wt.-%, more preferably from 25 to 40 wt.-%. ’. The process of any of embodiments 1 ’ to 24’, wherein the liquid aqueous feed stream provided in (i) further comprises a solvent, preferably a solvent comprising a monohydric alcohol, more preferably the monohydric alcohol is selected from the group consisting of methanol, ethanol, 1 -propanol, 2-propanol and 1 -butanol. ’. The process of any of embodiments 1 ’ to 25’, wherein the liquid aqueous feed stream provided in (i) further comprises a compound selected from the group consisting of a base, a Lewis acid and a combination thereof, preferably a base. 27’. The process of embodiment 26’, wherein in (i), the base is selected from the group consisting of metal hydroxides, wherein the metal of the metal hydroxide is preferably selected from the group consisting of Li, Na, K, Ca, and Mg, including combinations of two or more thereof, wherein more preferably the base comprise one or more metal hydroxides selected from the group consisting of LiOH, NaOH, KOH, Ca(OH)2, and Mg(OH)2, including mixtures of two or more thereof, preferably from the group consisting of NaOH, KOH, Ca(OH)2, and Mg(OH)2, including combinations of two or more thereof, wherein more preferably the base comprise one or more metal hydroxides selected from the group consisting of NaOH and KOH, including combinations of two thereof, more preferably the base comprises NaOH.

28’. The process of embodiment 26’ or 27’ wherein the liquid aqueous feed stream provided in (i) comprises from 0.1 to 8 wt.-% of the base, preferably from 0.3 to 7 wt.-%, more preferably from 4 to 6 wt.-%.

29’. The process of embodiment 26’, wherein in (i), the acid is selected from the group consisting of phosphoric acid and sulfuric acid, including combinations thereof.

30’. The process of embodiment 26’, wherein in (i), the Lewis acid is selected from the group consisting of metal polyacids, wherein the metal of the metal polyacid is preferably selected from the group consisting of Mo and W, including combinations of two or more thereof, wherein more preferably the Lewis acid comprise one or more metal polyacids selected from the group consisting of H2WO4 and (NH4)2MoO2, including combinations thereof.

31 ’.The process of any of embodiments 1 ’ to 30’, wherein the reaction conditions according to (ii) comprise a reaction pressure in the range of from 40 to 170 bar, preferably from 60 to 150 bar and more preferably from 80 to 120 bar.

32’. The process of any of embodiments T to 31 ’, wherein the reaction conditions according to (ii) comprise a temperature in the range of from 140 to 210 °C, preferably from 170 to 200 °C.

33’. The process of any of embodiments 1 ’ to 32’, wherein the reaction conditions according to (ii) comprise a liquid hourly space velocity in the range of from 0.1 to 5 IT¹, preferably of from 0.2 to 5 IT¹.

34’. The process of any of embodiments 1 ’ to 33’, wherein the liquid aqueous feed stream provided in (i) and fed into the reaction zone in (ii) further comprises H2.

35’. The process of embodiment 34’, wherein the liquid aqueous feed stream displays an H2 : sugar or sugar alcohol molar ratio of H2 to sugar or sugar alcohol in the range of from 1 to 8, preferably of from 1 .5 to 7, more preferably of from 1 .8 to 7. 36’. The process of any of embodiments T to 35’, wherein the liquid aqueous effluent stream removed in (iii) comprises from 10 to 95 mol%C of the one or more of a diol and a triol, each having two or three carbon atoms, preferably from 15 to 90 mol%C, more preferably from 20 to 85 mol%C, more preferably from 25 to 80 mol%C, based on 100 mol%C of the one or more of a sugar and a sugar alcohol, each having five or six carbon atoms, wherein mol%C is defined according to equation (I):

37’. The process of any of embodiments T to 36’, wherein the liquid aqueous effluent stream removed in (iii) comprises from 10 to 95 mol%C of 1 ,2-propanediol, glycerol and ethylene glycol, preferably from 15 to 90 mol%C, more preferably from 20 to 85 mol%C, more preferably from 25 to 80 mol%C, based on 100 mol%C of the one or more of a sugar and a sugar alcohol, each having five or six carbon atoms, wherein mol%C is defined according to equation (II):

(ii); wherein the subscript 1-3 refer to weight, molar mass and number of carbon atoms of 1 ,2- propanediol, glycerol and ethylene glycol, respectively. The subscript a refers to weight, molar mass and number of carbon atoms of the one or more of a sugar and a sugar alcohol.

38’. The process of any of embodiments T to 37’, wherein the liquid aqueous effluent stream removed in (iii) comprises from 10 to 80 mol%C of 1 ,2-propanediol, preferably from 15 to 75 mol%, more preferably from 20 to 70 mol%C, more preferably from 25 to 65 mol%C, based on 100 mol%C of the one or more of a sugar and a sugar alcohol, each having five or six carbon atoms, wherein mol%C is defined according to equation (III): (in); wherein the subscript a refers to weight, molar mass and number of carbon atoms of the one or more of a sugar and a sugar alcohol.

39’. The process of any of embodiments 1 ’ to 38’, wherein the process is a continuous process.

40’. The process of any of embodiments 1 ’ to 39’, wherein the process is operated in a trickle bed reactor.

DESCRIPTION OF THE FIGURES

The term „bar“ as used in the context of the present invention refers to „bar(abs)”, i.e. bar (absolute), sometimes also referred to as “bara”.

Figure 1 : Representation of X-ray diffraction pattern of the ZrO2 powder synthesized in Example 1-1. Markers in the graph represent the positions of diffraction signals given in database references for specific zirconium oxide crystal phases. References are taken from the Powder Diffraction File database and are identified by PDF numbers (XX-XXX-XXXX) in the legend. Matching the recorded signal positions with those of the references discloses the qualitative phase composition of the zirconium dioxide powder of Example 1 -1 .

Figure 2: Representation of X-ray diffraction patterns of Catalyst A-1 prior to use as synthesized in Example 2-1 and after operation according to Example 3-1 . Qualitative evaluation by matching reference patterns was done in the same way as for Figure 1 I Example 1-1 .

Figure 3: Representation of X-ray diffraction patterns of Catalyst B prior to use as synthesized in Comparative Example 1-1 and after use in Comparative Example 2-1. Qualitative evaluation by matching reference patterns was done in the same way as for Figure 1 I Example 1-1 .

EXPERIMENTAL SECTION

The present invention is further illustrated by the following examples and comparative examples.

Example 1-1 : Synthesis of support material for catalyst A-1

Zirconium oxide (ZrO2) powder was prepared by a sequence of precipitation, washing, drying and calcination steps. Zr(NOs)4 solution (10.7 wt.% Zr) was used as starting material. 25 wt.% NH3 solution was used as precipitation agent.

A mixing vessel was filled with one part (by weight) deionized water and one part 25 wt.% NH3 solution. No heating was applied and the mixture temperature was <40 °C. Subsequently, two parts (by weight) Zr(NOs)4 solution were added continuously to the stirred vessel over a period of 25 min. Following addition of the nitrate, the mixture pH was measured with a glass electrode. The value was adjusted to 7.5, using nitric acid, if required. The mixing vessel contents were heated to 85°C and stirred for an additional 6 h. The resulting suspension was filtered, and the filter cake was washed with deionized water until the electrical conductivity of the filtrate was below 200 piS/cm as measured with a WTW Cond 330i device equipped with a TetraCon 325 probe. The cake was then dried at a temperature of 120°C in a drying cabinet. The precursor obtained in this manner was calcined in flowing air at a temperature of 520°C over a period of 1 hour, leading to the final zirconium oxide powder.

The zirconium oxide powder obtained as described above was subjected to powder X-ray diffraction (PXRD) for characterization. Data was collected using a diffractometer (D8 Advance Series II, Bruker AXS GmbH) equipped with a LYNXEYE detector operated with a Copper anode X-ray tube running at 40kV and 40mA. The geometry was Bragg-Brentano, and air scattering was reduced using an air scatter shield. Prior to measurement, the sample was ground with an IKA TubeMill at 20000 rpm for 2 minutes in 30 second intervals. The sample was homogenized in a mortar and then pressed into a standard flat sample holder provided by Bruker AXS GmbH for Bragg-Brentano geometry data collection. A flat sample surface was achieved using a glass plate to compress and flatten the sample powder. Data was collected from the angular range 10 to 70° 20 with a step size of 0.02° 20 while the variable divergence slit was set to a fixed angle of 0.3°.

The recorded diffraction pattern is displayed in Figure 1 . Comparing signal positions with database references and contemplating relative signal intensities reveals a dominant contribution of the monoclinic crystal phase to the overall diffraction pattern.

The degree of sample crystallinity, the crystalline phase composition (w_Cryst) and crystallite sizes (CS) were computed from the recorded diffractogram using the modelling software DIF- FRAC. TOPAS V7 provided by Bruker AXS GmbH, Karlsruhe. The background intensity, the crystal structures of the identified phases and the instrumental parameters were accounted for in the regression of the recorded PXRD pattern. A first order Chebychev coefficient was used to simulate the background. The degree of crystallinity was defined as the percentage of signal area, after background subtraction, which was accounted for by crystalline phases:

Degree of Crystallinity

Where corresponds to the signal area attributed to crystalline sample components and A corresponds to the signal area attributed to X-ray amorphous sample components.

According to the evaluation, the as-synthesized ZrC>2 powder exhibited a total degree of crystallinity of 100 %. Amorphous phases were not required to represent the experimental PXRD pattern. 91 wt.% of crystalline ZrC>2 in the sample was found to have crystallized in the monoclinic phase, as opposed to 9 wt.% being present in the tetragonal crystalline phase. Thus, the sample was shown to consist predominantly of crystalline ZrC>2 of the monoclinic crystalline phase.

Example 2-1: Synthesis of the catalyst A-1 A catalyst powder nominally comprising 52 wt.% NiO, 17 wt.% CuO, and 31 wt.% ZrC>2 was prepared by a sequence of precipitation, washing, drying and calcination steps. Nickel nitrate (Ni(NOs)2), copper nitrate (Cu(NOs)2) and zirconium oxide (ZrC>2) powder from Example 1-1 were used as starting materials. Sodium carbonate (Na2COs) was used as precipitation agent. Nitrates and carbonates were used as aqueous solutions with pre-defined concentrations. The consumed amounts follow from the above catalyst composition and from the amount of ZrC>2.

Nickel nitrate (14.2 wt.% Ni) and copper nitrate (15.6 wt.% Cu) solutions were mixed to form a metal precursor solution. A mixing vessel was filled with 1.5 L deionized water and 156 g of zirconium oxide powder from Example 1-1 were added. The vessel was heated to 65°C. Subsequently, the metal precursor solution was continuously added to the mixing vessel over a period of 1 hour. 20 wt.% sodium carbonate solution was co-added in such a way, that the pH measured with a glass electrode was maintained at 6.2. After complete addition of the metal precursor solution, the pH was adjusted to 7.7 using sodium carbonate solution. The vessel contents were stirred at constant temperature for another 1 .5 hours.

The resulting suspension was filtered, and the filter cake was washed with deionized water until the electrical conductivity of the filtrate was below 200 pS/cm as measured with a WTW Cond 330i device equipped with a TetraCon 325 probe. The cake was then dried at a temperature of 120°C in a drying cabinet. The hydroxide-carbonate mixture obtained in this manner was calcined in flowing air at a temperature of 520°C over a period of 1 hour, leading to the stated oxide composition.

The catalyst powder was mixed with 3 % graphite by weight and 3x3 mm (diameter x height) cylindrical tablets were formed by compression. The tablets were calcined in flowing air at a temperature of 500°C over a period of 1 hour. Before use, the catalyst tablets were reduced in a flowing gas mixture, containing 50 vol.% H2 and 50 vol.% N2, at 280°C for 2 hours, followed by cooling and passivation with air at ambient temperature.

Example 3-1 : Sorbitol hydrogenolysis using catalyst A-1

The conversions using the catalyst A were run in a fixed bed reactor (10 mL). After loading of the catalyst, a standard reduction procedure was employed. To this end, the reactor including the catalyst was heated to 120°C under an N2 (120 nL/h) atmosphere. After reaching the temperature N2-feed was stopped and H2 (50nL/h) were added for one hour. Temperature was increased to 200°C and for another 4 hrs. After the procedure the reactor was cooled to room temperature under N2.

After reduction of the catalyst the feed, consisting of 40 wt.-% sorbitol and 5wt% NaOH, was pumped through the reactor under 110 bar and 200 °C under LHSV = 2.9 IT¹. Details are presented in Table 1-1 . Yields of glycols are depicted in mol%C, which describes the molar conversion of C-atoms of starting material (e.g. sorbitol) into the desired glycols 1 ,2-propanediol (1 ,2-PDO), ethylene glycol (EG) and glycerol (GLY). Yields were calculated according to the general equation (IV): The following equation gives an example of mol%C of 1 ,2-PDO in experiment 7 in Table 1-1.

12,8

72 g/mol

32.07 mol%C

40 g

182 g/mol

Table 1-1 : Conversion tests of sorbitol using the catalyst A-1. Example 4-1 : Analysis of original and spent catalyst A-1

Catalyst A-1 was analyzed prior to use (as synthesized according to Example 2-1) and after operation (sorbitol hydrogenolysis according to Example 3-1).

Radial side crush strength (SCS) of single tablets was used as a descriptor of mechanical stability. The analysis was performed on a commercial Sotax ST50 system operated in “Constant Speed” mode. For each measurement, the catalyst cylindrical tablet was positioned between a fixed bracket and the moving piston, approaching at 0.35 mm/s. The force required to press the piston forward was monitored until the catalyst tablet broke and the maximum force in Newton was recorded as SCS value of the tablet. The measurement was repeated for 20 individual tablets per catalyst type and the arithmetic mean of resulting values was formed.

Chemical stability was tested by elemental analysis. An aliquot of ground catalyst was submitted to measurements of metal content by ICP-OES (inductively coupled plasma optical emission spectroscopy). A mixture of H2SO4, HNO3 and HCIO4 was applied for sample digestion. After evaporating the digested solution to dryness, the solid residue was redissolved in dilute HCI (10 vol.-%). The resulting solution was analyzed on an Agilent 5100 spectrometer. Results were quantified after subtracting the blank value and using an external calibration. Results are given in terms of elemental ratios. This is to exclude the effects of absolute mass changes, which follow from catalyst reduction and from the adsorption of organics.

Table 2-1 : Analytical results on mechanical and chemical stability of catalyst A-1 synthesized in Example 2-1 .

In summary, no significant change was observed in the mechanical properties of catalyst tablets, indicating high mechanical stability of catalyst materials described in this invention. Moreover, results of chemical analysis indicate that there is no or very limited dissolution of catalyst components, which would shift the determined metal ratios. Thus, the presented material has high chemical stability, which makes it suitable for use in hydrothermal operation conditions and with basic additives in the feed mixture.

Table 3-1 : Analytical results on phase composition of catalyst A-1 synthesized in Example 2-1 determined by powder X-ray diffraction. *While NiCu alloy was used for a representative fit of the recorded diffraction patterns, contributions of metallic Ni and Cu would also be suitable for a description of the sample.

Characterization of as-synthesized Catalyst A-1 and of Catalyst A-1 after use in Example 3-1 by PXRD followed the methods described in Example 1-1. The respective powder X-ray diffraction patterns are given in Figure 2. Qualitative analysis of the signal positions and intensities as compared to references, shows that the monoclinic crystal phase of zirconium oxide is dominant in both samples. Contributions from amorphous matter and tetragonal ZrO₂ are negligible. The quantitative evaluation of the diffraction patterns does not show significant changes in crystalline phase composition (w_Cryst), nor in crystallite size (CS), underlining the discussed favorable stability characteristics of Catalyst A-1 (Table 3-1 ).

Comparative Example 1-1 : Synthesis of the catalyst B-1

A catalyst powder nominally comprising 51 wt.% NiO, 17 wt.% CuO, 1.5 wt.% MoOs, and 30.5 wt.% ZrO₂ was prepared by a sequence of precipitation, washing, drying and calcination steps. Nickel nitrate (Ni(NOs)2), ammonium heptamolybdate ((NH4)6MoyO24), copper nitrate (Cu(NOs)2) and zirconium acetate (Zr(C2H3O2)4) were used as starting materials. Sodium carbonate (Na2COs) was used as precipitation agent. The respective amounts used follow from the above catalyst composition and the given concentration levels.

Nickel nitrate, copper nitrate and zirconium acetate solutions were mixed with deionized water to obtain a solution with the following metal contents: 7.0 wt.% Ni, 2.4 wt.% Cu and 4.1 wt. Zr. The mixed solution was continuously added to a mixing vessel over a period of 2 hours. 20 wt.% sodium carbonate solution was co-added in such a way, that the pH measured with a glass electrode was maintained at 6.2. The vessel was temperature controlled at 65°C. After complete addition of the metal precursor solution, the pH was adjusted to 7.7 using sodium carbonate solution. The vessel contents were stirred at constant temperature for another 1 .5 hours.

The resulting suspension was filtered, and the filter cake was washed with deionized water until the electrical conductivity of the filtrate was below 200 pS/cm as measured with a WTW Cond 330i device equipped with a TetraCon 325 probe. The still moist filter cake was mixed with solid ammonium heptamolybdate. The cake was then dried at a temperature of 120°C in a drying cabinet. The hydroxide-carbonate mixture obtained in this manner was calcined in flowing air at a temperature of 520°C over a period of 1 hour, leading to the stated oxide composition.

The catalyst powder was mixed with 3% graphite by weight and 3x3 mm (diameter x height) cylindrical tablets were formed by compression. The tablets were calcined in flowing air at a temperature of 500°C over a period of 1 hour. Before use, the catalyst tablets were reduced in a flowing gas mixture, containing 50 vol.% H2 and 50 vol.% N2, at 280°C for 2 hours, followed by cooling and passivation with air at ambient temperature.

Comparative Example 2-1 : Sorbitol hydrogenolysis using catalyst B-1

The conversions using the catalyst B-1 were run in a fixed bed reactor (10 mL). After loading of the catalyst, a standard reduction procedure was employed. To this end, the reactor including the catalyst was heated to 120°C under an N2 (120 nL/h) atmosphere. After reaching the temperature N2-feed was stopped and H2 (50nL/h) were added for one hour. Temperature was increased to 200°C and for another 4 hrs. After the procedure, the reactor was cooled to room temperature under N2.

After reduction of the catalyst the feed, consisting of 40 wt.-% sorbitol and 5wt% NaOH, was pumped through the reactor under 110 bar and 200 °C under LHSV = 2.9 IT¹. Details are presented in Table 3-1 .

Yields of glycols are depicted in mol%C, which describes the molar conversion of C-atoms of starting material (e.g. sorbitol) into the desired glycols 1 ,2-propanediol (1 ,2-PDO), ethylene glycol (EG) and glycerol (GLY). Yields were calculated according to the general equation (IV):

The following equation gives an example of mol%C of 1 ,2-PDO in experiment 4 in Table 3-1 .

12,8 g

72 g/mol

33.22 mol%C

40 g

182 g/mol

Table 4-1 : Conversion tests of sorbitol using the catalyst B-1.

Comparative Example 3-1 : Analysis of original and spent catalyst B-1

Catalyst B-1 was analyzed prior to use (as synthesized according to Comparative Example 1-1 ) and after the operation (sorbitol hydrogenolysis according to Comparative Example 2-1 ). The methods were the same as in Example 4-1 . The only exception being that contributions from tetragonal ZrO2 to the diffraction pattern of catalyst B-1 could not be modelled by a defined crystalline phase. Thus, the regression accounted for a contribution from amorphous ZrO2 instead. The inability to model ZrC>2 in catalyst B-1 as a crystalline phase, likely stems from the presence of small crystallites with insufficient long-range order.

Table 5-1 : Analytical results on mechanical and chemical stability of catalyst B-1 synthesized according to Comparative Example 1-1.

As compared to Example 4-1 , the results show evidence of lacking mechanical and chemical catalyst stability of Catalyst B. The mechanical stability of catalyst tablets is severely degraded after the test, which may cause fines formation, increased pressure drop, or even reactor clogging in commercial operation. The elemental analysis shows a clear reduction in the Zr/Ni weight ratio of the spent catalyst. Chemical instability and leaching of the zirconium oxide support comprised in Catalyst B-1 is therefore likely. The material is not suitable for use in the tested reaction conditions.

Table 6-1 : Analytical results on phase composition of comparative catalyst B-1 synthesized in Comparative Example 1-1 determined by X-ray diffraction.

The X-ray diffraction pattern of as-synthesized Catalyst B-1 and of Catalyst B-1 after use in Comparative Example 2-1 are given in Figure 3. Notably, crystalline monoclinic ZrO₂ was not observed in these experiments, as can be deducted from the lack of corresponding signal peaks in recorded PXRD patterns. Instead, the zirconium oxide support is in amorphous configuration prior to use. After use, a defined tetragonal zirconium oxide phase has formed, exemplifying a strong change in the material, which likely underlies the unfavorable stability traits of Catalyst B-1 .

The PXRD pattern of Catalyst B-1 after use in Comparative Example 2-1 also shows evidence of SiC inert material, which could not be fully separated from the catalyst due to break-down of most tablets in the catalyst bed. Thus, quantitative evaluation is only given for Catalyst B-1 in the as-synthesized state. Sample crystallinity was overall lower for as-synthesized Catalyst B-1 than for Catalyst A-1 , underlining the presence of X-ray amorphous matter in Catalyst B-1 . Moreover, contributions of ZrO2 to the crystalline phase composition of Catalyst B-1 were insignificant. Crystallite sizes determined for Catalyst B-1 were lower than for Catalyst A-1 .

Overall, a low degree of crystallinity and the absence of crystalline Zr©2 in the monoclinic crystalline phase are indicative of the lacking stability of Catalyst B-1 .

Example 1 : Synthesis of the catalyst A

A catalyst powder containing 71.0 wt.% NiO, 6.0 wt.% ZrO2, 4.3 wt.% AI2O3, 18.7 wt.% SiO2 was prepared by a sequence of precipitation, washing, drying and annealing steps. Nickel nitrate (Ni(NOs)2), zirconium nitrate (Zr(NOs)4), sodium aluminate (NaAIO2) and diatomite (amorphous SiO2) were used as starting materials. Sodium carbonate (Na2COs) was used as precipitation agent. The respective amounts used follow from the above catalyst composition and the given concentration levels.

A 1.8 wt.% sodium aluminate solution was first prepared in a mixing vessel. Then, one weight equivalent of 20 wt.% sodium carbonate solution was added. The mixture was heated to 95°C, followed by the addition of diatomite. A second quantity of 20 wt.% sodium carbonate solution equivalent to the first was added to the mixing vessel. Then, zirconium nitrate solution (10.8 wt.% Zr content) was added over a period of 0.5 hours. The pH measured with a glass electrode was 9.7. The precipitation was finished by continuously adding nickel nitrate solution (13.5 wt.% Ni content) over a period of 1.5 hours, leading to a reduction in pH value. After complete addition the pH measured with a glass electrode was 8.3.

The resulting suspension was filtered, and the filter cake was washed with deionized water until the electrical conductivity of the filtrate was below 200 pS/cm as measured with a WTW Cond 330i device equipped with a TetraCon 325 probe. The cake was then dried at a temperature of 100°C in a drying cabinet or a spray dryer. The hydroxide-carbonate mixture obtained in this manner was annealed in flowing air at a temperature of 500°C over a period of 4 hours, leading to the stated oxide composition.

The catalyst powder was mixed with 4% graphite by weight and 3x3 mm (diameter x height) cylindrical tablets were formed by compression. Before use, the catalyst tablets were dried in flowing nitrogen at 350°C for 2 hours and reduced in a flowing gas mixture, containing 50 vol.% H2 and 50 vol.% N2, at 450°C for 12 hours, followed by cooling and passivation with air at ambient temperature.

Example 2: Synthesis of the catalyst B

A catalyst powder containing 51 wt.% NiO, 17 wt.% CuO, 1.5 wt.% MoOs, and 30.5 wt.% Zr©2 was prepared by a sequence of precipitation, washing, drying and annealing steps. Nickel nitrate (Ni(NOs)2), ammonium heptamolybdate ((NH4)6MoyO24), copper nitrate (Cu(NOs)2) and zirconium acetate (Zr(C2H3O2)4) were used as starting materials. Sodium carbonate (Na2COs) was used as precipitation agent. The respective amounts used follow from the above catalyst composition and the given concentration levels. Nickel nitrate, copper nitrate and zirconium acetate solutions were mixed with deionized water to obtain a solution with the following metal contents: 7.0 wt.% Ni, 2.4 wt.% Cu and 4.1 wt. Zr. The mixed solution was continuously added to a mixing vessel over a period of 2 hours. 20 wt.% sodium carbonate solution was co-added in such a way, that the pH measured with a glass electrode was maintained at 6.2. The vessel was temperature controlled at 65°C.

The resulting suspension was filtered, and the filter cake was washed with deionized water until the electrical conductivity of the filtrate was below 200 pS/cm as measured with a WTW Cond 330i device equipped with a TetraCon 325 probe. The still moist filter cake was mixed with solid ammonium heptamolybdate. The cake was then dried at a temperature of 100°C in a drying cabinet or a spray dryer. The hydroxide-carbonate mixture obtained in this manner was annealed in flowing air at a temperature of 500°C over a period of 4 hours, leading to the stated oxide composition.

The catalyst powder was mixed with 3% graphite by weight and 6x3 mm (diameter x height) cylindrical tablets were formed by compression. The tablets were annealed in flowing air at a temperature of 500°C over a period of 4 hours. Before use, the catalyst tablets were reduced in a flowing gas mixture, containing 50 vol.% H2 and 50 vol.% N2, at 240°C for 2 hours, followed by cooling and passivation with air at ambient temperature.

Examples 3 and 4: Mechanical and chemical testing of catalysts of Examples 1 and 2

Catalysts of Examples 1 and 2 were subjected to a test of catalyst stability. For this purpose, 15 g of reduced and air-stabilized catalyst was filled into the coaxial collector mesh of a 300 mL stainless steel autoclave. The autoclave was filled with 180 g of aqueous feed solution, containing 25 wt.-% sorbitol and 2 wt.-% sodium hydroxide (NaOH). The sealed autoclave was heated to 200° C. H2 gas was admitted to a pressure of 110 bar under continuous stirring. After 12 hours the reaction was stopped, the reactor cooled and depressurized. The spent catalyst samples were collected and dried.

Radial side crush strength (SCS) of single tablets was used as a descriptor of mechanical stability. The analysis was performed on a commercial Sotax ST50 system operated in “Constant Speed” mode. For each measurement, the catalyst cylindrical tablet was positioned between a fixed bracket and the moving piston, approaching at 0.35 mm/s. The force required to press the piston forward was monitored until the catalyst tablet broke and the maximum force in Newton was recorded as SCS value of the tablet.

The measurement was repeated for 20 individual tablets per catalyst type and the arithmetic mean of resulting values was formed.

Where the index “spent catalyst” refers to tablets that were subjected to reaction conditions, retrieved and dried, /indicates the counter of the consecutive measurements of 20 individual tablets. The same procedure and evaluation was performed for 20 catalyst tablets prior to use.

Where “fresh catalyst” refers to the reduced, air-stabilized tablets prior to subjection to reaction conditions.

The remaining mechanical stability after subjecting catalysts to reaction conditions was expressed as percentage of the values of the fresh catalysts according to the following equation:

The solid-free reaction solution from above-described tests was submitted to measurements of metal content by ICP-OES (inductively coupled plasma optical emission spectroscopy). A mixture of H2SO4, HNO3 and HCIO4 was applied for sample digestion. After evaporating the digested solution to dryness, the solid residue was redissolved in dilute HCI (10 vol.-%). The resulting solution was analyzed on an Agilent 5100 spectrometer. Results were quantified after subtracting the blank value and using an external calibration. Results of all measurements related to Examples 3 and 4 are given in Table 1 .

Table 1 : Mechanical and chemical stability of catalysts of Examples 1 to 2.

The test results for dissolved nickel in the reaction solution indicates that chemical corrosion is low for the catalysts described in Examples 1 and 2. The catalysts of Examples 1 and 2 also retain their tablet shape after being subjected to the test conditions. The relative decline in SCS observed for the catalyst of Example 1 is compensated by a high absolute SCS value of the spent catalyst. For the catalyst of Example 2, the SCS is almost completely retained after the stated test. Thus, the catalysts of Examples 1 and 2 have high stability in terms of corrosion and mechanical degradation under conditions relevant to the invention.

Comparative Example 1 : Synthesis of the catalyst C

A catalyst powder containing 72.3 wt.% NiO, 8 wt.% ZrO2, 19.5 wt.% AI2O3 and 0.2 wt.% Na2O was prepared by a sequence of precipitation, washing, drying and annealing steps. Nickel nitrate (Ni(NOs)2), zirconium oxide (ZrO2) and aluminum nitrate (AI(NOs)3) were used as starting materials. Sodium carbonate (Na2COs) was used as precipitation agent. The respective amounts used follow from the above catalyst composition and the given concentration levels. First, deionized water and zirconium oxide powder were added to a mixing vessel to form a slurry containing 1.8 wt.% of solids. In a separate vessel, nickel nitrate and aluminum nitrate solutions were mixed with deionized water to obtain a solution with the following concentrations calculated based on metals: 7.0 wt.% Ni and 1 .3 wt.% Al. The mixed solution was continuously added to the mixing vessel containing the zirconium oxide suspension over a period of 0.25 hours. 20 wt.% sodium carbonate solution was co-added in such a way, that the pH measured with a glass electrode was maintained at 8.1 . The vessel was temperature controlled at 50°C.

The catalyst powder was mixed with 3% graphite by weight and 5x3 mm (diameter x height) cylindrical tablets were formed by compression. Before use, the catalyst tablets were annealed in flowing air at a temperature of 460°C over a period of 4 hours. Subsequent reduction was performed in a flowing gas mixture, containing 50 vol.% H2 and 50 vol.% N2, at 400°C for 5 hours, followed by cooling and passivation with air at ambient temperature.

Comparative Example 2: Synthesis of catalyst D

A catalyst powder containing 58 wt.% CuO, 30 wt.% AI2O3 and 12 wt.% MnC>2 was prepared by a sequence of precipitation, washing, drying and annealing steps. Copper nitrate (Cu(NC>3)2), sodium aluminate (NaAIO2) and manganese nitrate (Mn(NC>3)2) were used as starting materials. Sodium carbonate (Na2COs) was used as precipitation agent. The respective amounts used follow from the above catalyst composition and the given concentration levels.

Copper nitrate (15.5 wt.% Cu content), manganese nitrate (15 wt.% Mn content)and sodium aluminate solutions (12.5 wt.% Al) were prepared in accordance with the target catalyst composition. These solutions were continuously added to a mixing vessel containing deionized water equivalent to one fourth of the volume of copper nitrate solution. 20 wt.% sodium carbonate solution was co-added in such a way, that the pH measured with a glass electrode was maintained at 7.0. The vessel was temperature controlled at 25°C.

The resulting suspension was filtered, and the filter cake was washed with deionized water until the electrical conductivity of the filtrate was below 200 pS/cm as measured with a WTW Cond 330i device equipped with a TetraCon 325 probe. The cake was then dried at a temperature of 100°C in a drying cabinet or a spray dryer. The hydroxide-carbonate mixture obtained in this manner was annealed in flowing air at a temperature of 600°C over a period of 4 hours, leading to the stated oxide composition.

The catalyst powder was mixed with 3% graphite by weight and compressed into granules in such a way to obtain a specific bulk density equal to 40-50% of the value of the corresponding tablet product. The granules were then compressed to form 3.2x3.2 mm (diameter x height) cylindrical tablets. The catalyst tablets were annealed in flowing air at a temperature of 750°C over a period of 4 hours, leading to a specific bulk density of 1 .1 g/mL. Subsequent reduction was performed in a flowing gas mixture, containing 50 vol.% H2 and 50 vol.% N2, at 220°C for 2 hours, followed by cooling and passivation with air at ambient temperature.

Comparative Example 3: Synthesis of catalyst E

A catalyst in extrudate shape was prepared according to the procedure disclosed in Example 1 of WO 2020/117532 A1 . The calcination temperature was chosen as 600°C. The resulting material contained 76.2 wt.-% CuO, 13.6 wt.-% SiO2, 5.9 wt.-% CaO, 0.9 wt.-% MnO2 and 3.4 wt.-% Na2O. Before use, the catalyst tablets were reduced in a flowing gas mixture, containing 50 vol.% H2 and 50 vol.% N2, at 220 °C for 2 hours, followed by cooling and passivation with air at ambient temperature.

Comparative Examples 4 to 6: Mechanical and chemical testing of catalysts of Comparative Examples 1 to 3

Catalysts of Comparative Examples 1 to 3 were subjected to a test of catalyst stability as described for the Examples 3 and 4. For the catalysts of Comparative Examples 1 and 2, the radial side crush strength (SCS) of a single tablet was used as a descriptor of mechanical stability. The measurement was performed as described in Examples 3 and 4.

Cutting hardness (CH) of single extrudate strands was used as a descriptor of mechanical stability for the catalyst of Comparative Example 3. The analysis was performed on a Zwick BZ2.5/TS1S system. For each single strand measurement, the catalyst extrudate was positioned between a fixed bracket and a moving blade of 0.3 mm width, approaching at a constant velocity of 0.027 mm/s. The force required to push the blade forward was monitored until the strand broke and the maximum force in Newton was recorded as SH value of the strand. Breaking was detected, when the measured force fell 30% below the maximum force of the current test.

The measurement was repeated for 20 individual strands per catalyst type and the arithmetic mean of resulting values was formed.

Where the index “spent catalyst” refers to extrudate strand that were subjected to reaction conditions, retrieved and dried, /indicates the counter of the consecutive measurements of 20 individual strands.

The same procedure and evaluation was performed for 20 catalyst strands prior to use.

The solid-free reaction solution from above-described tests was submitted to measurements of metal content by ICP-OES (inductively coupled plasma optical emission spectroscopy). The measurement details are the same as in Examples 3 and 4. Results of all measurements related to Comparative Examples 5 and 6 are given in Table 2.

Table 2: Mechanical and chemical stability of catalysts of Comparative Examples 3 and 4. ^a measurement not possible due to loss of tablet integrity ^b not applicable

The test results for dissolved metals in the reaction solution indicates that chemical corrosion takes place for the catalyst described in Comparative Example 2, but not for the catalysts of Comparative Examples 1 and 3. However, the catalyst of Comparative Example 1 suffers from loss of tablet integrity under test conditions. The catalysts of Comparative Examples 2 and 3 retain their shape after being subjected to test conditions. However, the relative decline in SCS or SH with the catalysts of Comparative Examples 2 and 3 is high as compared to the catalysts of Examples 1 and 2. The remaining absolute SCS or SH value of the spent catalysts of Comparative Examples 2 and 3 is also low. Thus, the Comparative Examples 3 to 6 demonstrate that the catalysts of Comparative Examples 1 to 3 have low stability in terms of corrosion and mechanical degradation in conditions relevant to the inventive process.

Example 5: Conversion tests of sorbitol using the catalyst of Example 1

The conversions using the catalyst of Example 1 were run in a fixed bed reactor (200 mL). After loading of the catalyst, no additional reduction procedure was employed. The feed, consisting of 10 to 40 wt.-% sorbitol and 0.0 to 0.45 wt.-% NaOH, was pumped through the reactor under 110 bar and 200 °C under LHSV = 0.3 IT¹. Details are presented in Table 3. Yields of glycols are depicted in mol%C, which describes the molar conversion of C-atoms of starting material (e.g. sorbitol) into the desired glycols 1 ,2-propanediol (1 ,2-PDO), ethylene glycol (EG) and glycerol (GLY). Yields were calculated according to the general equation (IV):

The following equation gives an example of mol%C of 1 ,2-PDO in experiment 4 in table 3.

12,8 g

72 g/mol

40,5 mol%C

40 g

182 g/mol

Table 3: Conversion tests of sorbitol using the catalyst of Example 1 .

Table 5 shows full conversion of sorbitol under all applied reaction conditions. Selectivity of up to 40.5 mol%C for 1 ,2-propanediol (1 ,2 PDO), 22.5 mol%C for glycerol (GLY) and 16.0 mol%C for ethylene glycol (EG) were achieved. Yields of 1 ,2-PDO, GLY and EG are depicted in mol%C as calculated according to equation (I).

Example 6: Conversion tests of sorbitol using the catalyst of Example 1

The conversions using the catalyst of Example 1 were run in a fixed bed reactor (200 mL). After loading of the catalyst, no additional reduction procedure was employed. The feed, consisting of 40 wt.-% sorbitol and 0.45 wt.-% NaOH, was pumped through the reactor under 110 to 150 bar, 200 °C and LHSV = 0.15 - 1.2 IT¹. Details are presented in Table 4.

Table 4: Conversion tests of sorbitol using the catalyst of Example 1 .

Table 4 shows full conversion of sorbitol under all applied reaction conditions. Selectivity of up to 30.7 mol%C for 1 ,2-propanediol (1 ,2-PDO), 23.5 mol%C for glycerol (GLY) and 15.4 mol %C for ethylene glycol (EG) were achieved. Yields of 1 ,2-PDO, GLY and EG are depicted in mol%C as calculated according to equation (I).

Examples 7 and 8 and Comparative Example 7: High throughput screening

The catalysts of Examples 1 and 2 and Comparative Example 1 were tested in a high throughput reactor system, which can include up to 16 parallel fixed-bed reactors. The reactors were loaded with 0.6 mL or 2.4 mL catalyst to establish different LHSVs in a particle size fraction of 250-315 pm. All reactors are connected to the same liquid feed and same educt gases and can be individually heated to the reaction temperature. The products are condensed in liquid condenser while the gases continue to a multiport valve and are analyzed by an online gas chromatograph. The condensed liquid samples are analyzed offline by offline gas chromatography and HPCL. The throughput reactor system is demonstrated in Figure 1 .

Example 7: High throughput screening of sorbitol using the catalyst of Example 1

The reactions were run in a fixed bed reactor (0.6 mL) for 48 hours per Experiment. After loading of the catalyst, no additional reduction procedure was employed. The feed, consisting of 40 wt.- % sorbitol and from 0.72 to 4.88 wt.-% NaOH, was pumped through the reactor under 110 bar . Temperature and space velocity were adjusted throughout the series of Experiments. Details are presented in Table 5.

Table 5: Results from high throughput screening of sorbitol using the catalyst of Example 1 . Table 5 shows a conversion of sorbitol of up to 100 mol%C under all applied reaction conditions. Selectivity of up to 43.83 mol%C for 1 ,2-propanediol (1 ,2 PDO), 26.4 mol%C for glycerol (GLY) and 15.00 mol%C for ethylene glycol (EG) were achieved. Yields of 1 ,2-PDO, GLY and EG are depicted in mol%C as calculated according to equation (I).

Example 8: High throughput screening of sorbitol using the catalyst of Example 2

The conversions using the catalyst of Example 2 were run in a fixed bed reactor (0.6 mL) for 48 hours per Experiment. After loading of the catalyst, no additional reduction procedure was employed. The feed, consisting of 40 wt.-% sorbitol and from 0.72 to 4.88 wt.-% NaOH, was pumped through the reactor under 110 bar. Temperature and space velocity were adjusted throughout the series of Experiments. Details are presented in Table 6.

Table 6: Results from high throughput screening of sorbitol using the catalyst of Example 2.

Table 6 shows a conversion of sorbitol of up to 100 mol%C under all applied reaction conditions Selectivity of up to 45.31 mol%C for 1 ,2-propanediol (1 ,2 PDO), 23.99 mol%C for glycerol (GLY) and 16.13 mol%C for ethylene glycol (EG) were achieved. Yields of 1 ,2-PDO, GLY and EG are depicted in mol%C as calculated according to equation (I).

Comparative Example 7: High throughput screening of sorbitol using the catalyst of Comparative Example 1

The reactions using the catalyst of the Comparative Example 1 were run in a fixed bed reactor (0.6 mL) for 48 hours per Experiment. After loading of the catalyst, no additional reduction procedure was employed. The feed, consisting of 40 wt.-% Sorbitol and from 0.72 to 4.88 wt.-% NaOH, was pumped through the reactor under 110 bar. Temperature and space velocity were adjusted throughout the series of Experiments. Details are presented in Table 7.

Table 7: Results from high throughput screening of sorbitol using the catalyst of the Comparative Example 1.

Table 7 shows a conversion of sorbitol of up to 100 mol%C under all applied reaction conditions. Selectivity of up to 44.89 mol%C for 1 ,2-propanediol (1 ,2-PDO), 22.7 mol%C for glycerol (GLY) and 15.29 mol%C for ethylene glycol (EG) were achieved. Yields of 1 ,2-PDO, GLY and EG are depicted in mol%C as calculated according to equation (I). However, Comparative Example 4 revealed insufficient mechanical stability of the catalyst of Comparative Example 1 . Accordingly, the presented conversion and selectivity results of Table 7 cannot be sustainably achieved in an industrial process utilizing the catalyst of Comparative Example 1.

Comparative Example 8: High throughput screening of sorbitol using the catalyst of Comparative Example 2

The reactions using the catalyst of the Comparative Example 2 were run in a fixed bed reactor (0.6 mL) for 48 hours per Experiment. After loading of the catalyst, no additional reduction procedure was employed. The feed, consisting of 40 wt.-% Sorbitol and from 0.72 to 4.88 wt.-% NaOH, was pumped through the reactor under 110 bar. Temperature and space velocity were adjusted throughout the series of Experiments. Details are presented in Table 8.

Table 8: Results from high throughput screening of sorbitol using the catalyst of the Comparative Example 2.

Table 8 shows a conversion of sorbitol of up to 100 mol%C under all applied reaction conditions. Selectivity of up to 42.71 mol%C for 1 ,2-propanediol (1 ,2-PDO), 7.15 mol%C for glycerol (GLY) and 9.76 mol%C for ethylene glycol (EG) were achieved. Yields of 1 ,2-PDO, GLY and EG are depicted in mol%C as calculated according to equation (I). Testing had to be aborted after Experiment 4 due to rising pressure drop over the reactor caused by loss of catalyst stability. Accordingly, the presented conversion and selectivity results of Table 8 cannot be sustainably achieved in an industrial process utilizing the catalyst of Comparative Example 2.

Comparative Example 9: High throughput screening of sorbitol using the catalyst of Comparative Example 3

The reactions using the catalyst of the Comparative Example 3 were run in a fixed bed reactor (0.6 mL) for 48 hours per Experiment. After loading of the catalyst, no additional reduction procedure was employed. The feed, consisting of 40 wt.-% Sorbitol and from 0.72 to 4.88 wt.-% NaOH, was pumped through the reactor under 110 bar. Temperature and space velocity were adjusted throughout the series of Experiments. Details are presented in Table 9.

Table 9: Results from high throughput screening of sorbitol using the catalyst of the Comparative Example 3.

Table 9 shows a conversion of sorbitol of up to 100 mol%C under all applied reaction conditions. Selectivity of up to 41 .98 mol%C for 1 ,2-propanediol (1 ,2-PDO), 11 .51 mol%C for glycerol (GLY) and 10.37 mol%C for ethylene glycol (EG) were achieved. Yields of 1 ,2-PDO, GLY and EG are depicted in mol%C as calculated according to equation (I). In Table 9 Experiment 1 and 7 show results obtained at identical operating conditions at the start and the end of the catalyst testing procedure. In Experiment 7, the conversion of sorbitol is significantly below the value of Experiment 1 , indicating a loss in catalyst activity and therefore lacking catalyst stability. Accordingly, the presented conversion and selectivity results of Table 9 cannot be sustainably achieved in an industrial process utilizing the catalyst of Comparative Example 3.

Cited prior art:

- US 6,900,361 B2

- EP 2 403 818 A1

- US 5,814,112 A

- US 6,152,975 A

- Journal of Environmental Chemical Engineering 2022, 10, 107229

- Wang et al. (ChemCatChem 2019, 11 , 4123-4129 - Xin Jin et al. (ACS Catal. 2015, 5, 6545-6558

Chen et al. (Catalysis Communications 2013, 39, 86-89

Claims

(iii) removing a liquid aqueous effluent stream comprising the one or more of a monoalcohol, a diol and a triol from the reaction zone; wherein the catalyst comprises zirconium oxide, wherein from 5 to 60 wt.-% of the catalyst consist of zirconium oxide, calculated as ZrC>2.

2. The process of claim 1 , wherein the catalyst further comprises metal oxides, wherein the metal of the metal oxides is preferably selected from the group consisting of Na, Mg, Al, Si, K, Ca, Ti, Mn, Co, Cu, Zn, Nb, Mo, La, Hf, and W, including combinations of two or more thereof, more preferably from the group consisting of Na, Mg, Al, Si, Ca, Ti, Mn, Co, Cu, La, and Hf, including combinations of two or more thereof, more preferably from the group consisting of Al, Si, Mn, Co and Cu, including combinations of two or more thereof, more preferably from the group consisting of Cu and Co, including combinations thereof, more preferably the metal of the metal oxides is Cu, wherein more preferably the catalyst further comprises metal oxides selected from the group consisting of CuO, CoO, CO2O3 and CO3O4 including mixtures thereof, more preferably the catalyst further comprises CuO.

3. The process of claim 1 or 2, wherein the catalyst has a degree of crystallinity in the range of from 60 to 100 %, based on the total catalyst, as determined from the powder X-ray diffraction pattern of the catalyst.

4. The process of any of claims 1 to 3, wherein the powder X-ray diffraction pattern of the catalyst shows signal peaks in the ranges of from 28 to 29° and from 31 to 32° 20 angle.

5. The process of any of claims 1 to 4, wherein the catalyst comprises a monoclinic crystalline phase comprising zirconium oxide and optionally a tetragonal crystalline phase comprising zirconium oxide, preferably wherein the monoclinic crystalline phase comprises zirconium oxide in an amount of from 5 to 100 wt.-% and the tetragonal crystalline phase comprises zirconium oxide in an amount of from 0 to 20 wt.-%, based on 100 wt.-% of all crystalline phases in the catalyst, as determined from the powder X-ray diffraction pattern of the catalyst.

6. The process of any of claims 1 to 5, wherein from 40 to 90 wt.-% of the catalyst consists of nickel, preferably from 45 to 85 wt.-%, more preferably from 50 to 80 wt.-%, calculated as NiO.

7. The process of any of claims 1 to 6, wherein from 40 to 90 wt.-% of the catalyst consists of nickel and copper, preferably from 60 to 85 wt.-%, calculated as NiO and CuO.

8. The process of any of claims 1 to 7, wherein the one or more of the sugar having six carbon atoms is preferably selected from the group consisting of glucose, galactose, maltose, lactose, sucrose, allose, altrose, mannose, gulose, idose, talose, including combinations of two or more thereof.

9. The process of any of claims 1 to 8, wherein the one or more of a mono-alcohol, a diol and a triol, each having two or three carbon atoms is selected from the group consisting of 1 ,2- propanediol, ethylene glycol, 1 ,3-propanediol, glycerol, 1 -propanol, 2-propanol and ethanol, including combinations of two or more thereof.

10. The process of claim 9, wherein the one or more of a diol and a triol, each having two or three carbon atoms is selected from the group consisting of 1 ,2-propanediol, ethylene glycol and glycerol including combinations of two or more thereof.

11 . The process of any of claims 1 to 10, wherein the liquid aqueous feed stream in (ii) comprises from 20 to 99 wt.-% of a sugar or a sugar alcohol, each having three, five or six carbon atoms, preferably from 25 to 60 wt.-%, more preferably from 25 to 40 wt.-%.

12. The process of any of claims 1 to 11 , wherein the liquid aqueous feed stream provided in (i) further comprises a compound selected from the group consisting of a base, a Lewis acid and a combination thereof, preferably the liquid aqueous feed stream provided in (i) further comprises a base, wherein preferably the base is selected from the group consisting of metal hydroxide and metal carbonate, wherein the metal of the metal hydroxide and of the metal carbonate is preferably selected from the group consisting of Li, Na, K, Ca, and Mg, including combinations of two or more thereof, wherein more preferably the base comprises one or more metal hydroxide and meatal carbonate selected from the group consisting of LiOH, NaOH, Na2CC>3, KOH, K2CO3, Ca(OH)2, and Mg(OH)2, including mixtures of two or more thereof, preferably from the group consisting of NaOH, Na2CO3, KOH, K2CO3, Ca(OH)2 and Mg(OH)2, including combinations of two or more thereof, wherein more preferably the base comprises one or more metal hydroxide and metal carbonates selected from the group consisting of NaOH, Na2CO3, KOH and K2CO3, including combinations of two thereof, more preferably the base comprises, preferably is NaOH.

13. The process of any of claims 1 to 12, wherein the reaction conditions according to (ii) comprise a reaction pressure in the range of from 40 to 250 bar, preferably from 60 to 200 bar and more preferably from 80 to 120 bar.

14. The process of any of claims 1 to 13, wherein the reaction conditions according to (ii) comprise a temperature in the range of from 140 to 220 °C, preferably from 170 to 200 °C.

15. The process of any of claims 1 to 14, wherein the liquid aqueous feed stream provided in (i) and fed into the reaction zone in (ii) further comprises H2.

16. A process for preparing a catalyst, preferably the catalyst for the process of any of claims 1 to 15, the process comprising

(a) preparing a first mixture comprising zirconium oxide and water;

(d) removing the water from the slurry obtained in (c), obtaining a solid;

(f) calcining the solid obtained in (d), preferably the dried solid obtained in (e), at a temperature in the range of 300 to 700 °C, obtaining a catalyst comprising nickel oxide and zirconium oxide, wherein from 5 to 60 wt.-% of the catalyst consist of zirconium oxide, calculated as ZrC>2, preferably the catalyst for the process of any of claims 1 to 15.