Process and catalyst for producing gamma-valerolactone

Abstract

The present invention relates to a heterogeneous ruthenium catalyst, which comprises elemental ruthenium supported on activated carbon carrier, where the catalyst has a total pore volume in the range of 0.3 to 0.6 ml / g, in particular in the range of 0.35 to 0.5 ml / g, and where pores having a pore diameter in the range of 10 to 200 nm contribute at least 50%, in particular at least 60%, especially at least 70%, to the total pore volume of the heterogeneous ruthenium catalyst. The present invention also relates to a process for the production of gamma-valerlactone, which comprises a hydrogenation of an levulinic acid or alkyl levulinate, such as methyl levulinate or ethyl levulinate, with hydrogen in the presence of a heterogeneous ruthenium catalyst, which comprises elemental ruthenium supported on activated carbon carrier, where the catalyst has a total pore volume in the range of 0.3 to 0.6 ml / g, and where pores having a pore diameter in the range of 10 to 200 nm contribute at least 50% to the total pore volume of the heterogeneous ruthenium catalyst.

Description

[0001] Process and catalyst for producing gamma-valerolactone

[0002] The present invention relates to a process for and a ruthenium catalyst for producing gamma- valerolactone, which comprises a hydrogenation of a levulinic acid compound in the presence of a heterogeneous ruthenium catalyst.

[0003] Gamma-valerolactone (GVL), also referred to as 5-methyloxolan-2-on, is a valuable organic compound that can be used for numerous purposes. For example, it is a promising substitute for potentially problematic solvents, such as N-methyl pyrrolidone and dimethylformamide, and can be used for the production of adipic acid. GVL can be produced from levulinic acid which itself can be obtained biological feedstock. GVL was identified as a potential "green fuel”, as it retains 97% of the energy of glucose and can be blended by itself in gasoline where it performs comparably to conventional ethanol / gasoline mixtures. Morover, GVL has been suggested as a solvent in the thermocatalytic production of soluble carbohydrates from lignocellulosic materials, such as corn stover and wood at high yields.

[0004] WO 02 / 074760 desribes the production of GVL by hydrogenation of levulicinc acid in the presence of a catalytic amount of supported transition metal catalyst having both a hydrogenation and a ring-closing function. The catalyst can be carbon supported ruthenium catalysts. The experiments were carried out in dioxan and often resulted in poor selectivity towards GVL and low conversion of levulinic acid, respectively.

[0005] EP 2537840 suggests overcomming the disadvantages of poor selectivity towards GVL and low conversion of levulinic acid by carrying out the hydrogenation of levulinic acid in the presence of a solid ruthium catalyst, e. g. a carbon supported ruthenium catalysts, and at least 0.08% b.w. of water relative to the amount of levulinic acid. However, the conversion of levulinic acid was not satisfactory.

[0006] EP 3184517 suggests that the poor selectivity towards GVL can be overcome by hydrogenating levulinic acid under conditions that produce 4-hydroxyvaleric acid followed by conversion of the 4-hydroxyvaleric acid under conditions where further hydrogenation is prevented. The process of requires the hydrogenation of levulinic acid at low temperatures of at most 120°C and a separate reaction step for the conversion 4-hydroxyvaleric to GVL to provide the desired selectivity, which results in low conversion rates and makes the process less economic.

[0007] It was surpsingly found that a novel carbon supported heterogeneous ruthenium catalyst having a total pore volume in the range of 0.3 to 0.6 ml / g and where pores having a pore diameter in the range of 10 to 200 nm contribute at least 50% a gamma-valerolactone to the total pore volume of the catalyst provide

[0008] M / BASFTR-4221-PC GVL with high selectivity and high conversion rates in a process which comprises the hydrogenation of levulinic acid or an alkyl levulinate in the presence of said heterogeneous ruthenium catalyst.

[0009] Therefore, the present invention relates to a heterogeneous ruthenium catalyst, which comprises elemental ruthenium supported on a porous carbon carrier, where the catalyst has a total pore volume in the range of 0.3 to 0.6 ml / g, in particular in the range of 0.35 to 0.5 ml / g, and where pores having a pore diameter in the range of 10 to 200 nm contribute at least 50%, in particular at least 60%, especially at least 70%, to the total pore volume of the heterogeneous ruthenium catalyst.

[0010] The present invention also relates to a process for the production of gamma-valerlactone, which comprises the hydrogenation of levulinic acid or of an alkyl levulinate, such as methyl levulinate or ethyl levulinate, with hydrogen the presence of a heterogeneous ruthenium catalyst, which comprises elemental ruthenium supported on porous carbon carrier, where the catalyst has a total pore volume in the range of 0.3 to 0.6 ml / g, in particular in the range of 0.35 to 0.5 ml / g, and where pores having a pore diameter in the range of 10 to 200 nm, in particular pores having a pore diameter in the range of 10 to 100 nm, contribute at least 50%, in particular at least 60%, especially at least 70%, to the total pore volume of the heterogeneous ruthenium catalyst.

[0011] The catalyst and process of the present invention provide several benefits. First of all, the use of the catalyst in the hydrogenation of levulinic acid or alkyl levulinate, in particular the methyl levulinate or the ethyl levulinate, provides GVL with high conversion rates and high selectivities towards the formation of GVL. In particular conversion rates are much higher than in hydrogenation reactions using ruthenium catalysts containing ruthenium on oxidic carriers, such as zirconium oxide or aluminium oxide, or other carbon supported heterogeneous ruthenium catalysts. The heterogeneous ruthenium catalysts of the present invention show no significant loss of activity when used in the process of the present invention, even after prolonged use and a high selectivity towards the formation of 4-hydroxyvalerates and gamma valerolactone. In particular overreduction to valeric acid or alkyl valerate or 2-methyltetrahydrofurane is minimized or does not occur at all. The process does not necessarily require a second reaction step for the transformation of the intermediately formed 4-hydroxyvaleric acid or alkyl 4-hydroxyvalerate, respectively, into GVL. The process of the inventive process can be easily carried out in fixed bed reactors allowing an easy and efficient upscaling to industrial production and high catalyst load. The process is particularly suitable for using an alkyl levulinate starting material, which turned out to cause less corrosions which is sometimes faced when using levulinic acid feedstock. Moverover, the alkanol formed in the reaction can be easily recovered from the reaction product and used for other purposes.

[0012] M / BASFTR-4221-PC Here and in the following, the values of the pore volume and the pore diameter of the catalyst as well as of the porous carbon carrier, in particular the distribution of pore sizes with respect to the pore volume, is determined by mercury intrusion porosimetry (MIP) in accordance with DIN ISO 15901-1 :2019 DE. For further details on the determination of the total pore volume and distribution of pore sizes with respect to the pore volume we refer to the experimental part of this application.

[0013] The ruthenium catalyst of the present invention contains elemental ruthenium on a porous carbon carrier and has a carachteristic pore volume and a characteristic distribution of pore sizes which is characterized in that the majority of the pore volume of the catalyst, I. e. at least 50%, in particular at least 60%, especially at least 70% of the pore volume, e. g. 50 to 100% or 50 to 99%, in particular 60 to 99% or 60 to 95%, especially 70 to 95% or 70 to 90% of the pore volume of the catalyst, is provided by pores having a pore diameter in the range of 10 to 200 nm.

[0014] In particular at least 50%, more particular at least 60%, especially at least 70% of the pore volume, e. g. 50 to 100% or 50 to 99%, in particular 60 to 99% or 60 to 95%, especially 70 to 95% or 70 to 90% of the pore volume of the catalyst, is provided by pores having a pore diameter in the range of 10 to 100 nm.

[0015] In particular, the pores having a pore diameter of less than 10 nm contribute at most 20%, more particular at most 15%, e. g. 0 to 20% or 1 to 20%, in particular 1 to 15% or 5 to 15% to the total pore volume of the catalyst of the present invention.

[0016] In particular, the pores having a pore diameter of more than 200 nm contribute at most 20%, more particular at most 15%, e. g. 0 to 20% or 1 to 20%, in particular 1 to 15% or 5 to 15% to the total pore volume of the catalyst of the present invention.

[0017] In particular, the pores having a pore diameter of more than 100 nm contribute at most 20%, more particular at most 15%, e. g. 0 to 20% or 1 to 20%, in particular 1 to 15% or 5 to 15% to the total pore volume of the catalyst of the present invention.

[0018] All percentages mentioned in respect to pore volume of the catalyst of the present invention refer to volume percentages (vol%) with respect to the total pore volume of the catalyst.

[0019] In particular, catalysts are preferred, where pores having a pore diameter in the range of 10 to 200 nm contribute to the total pore volume in an amount in the range of 0.2 to 0.6 ml / g, especially in the range of 0.25 to 0.5 ml / g. More particularly, catalysts are preferred, where pores having a pore diameter in the

[0020] M / BASFTR-4221-PC range of 10 to 100 nm contribute to the total pore volume in an amount in the range of 0.2 to 0.6 ml / g, especially in the range of 0.25 to 0.5 ml / g.

[0021] Generally, the catalyst of the present invention has a BET surface of at least 150 m2 / g, preferably at least 200 m2 / g, in particular in the range of 150 to 400 m2 / g, especially in the range of 200 to 400 m2 / g, as determined in accordance with DIN ISO 9277 using nitrogen physisorption.

[0022] The catalyst may have any form and size wich is suitable for heterogeneous catalysts. For example, the catalyst can have the form of a powder, in irregular form, such as split, in the form of a shaped body, such as strands, lobes, rings or pellets of the catalyst material, or in the form of spheres of the catalyst material. Herein, the term lobes refers to shaped bodies in the form of strands having a cross section in the form of at least 2 circles which overlap each other including trilobal, quadlobal, pentalobal or hexalobal shapes. The lobes may have a central circular hole.

[0023] Typical catalyst powders have a weight average particle sizes of not more than 200 pm, e. g. in the range of 5 to 200 pm, in particular in the range of 10 to 100 pm. In contrast thereto, the catalyst materials having split form as well as shaped bodies of catalyst material have larger sizes, e. g. average diameters in the range of 500 pm to 20.000 pm, in particular in the range of 500 pm to 10.000 pm or in the range of 500 to 5000 pm. Here, the values of the particle size refer to the D50 value as determined by sieving in accordance with DIN 66165-1 2018. In particular, shaped bodies have dimensions of at least 1.0 mm, in particular at least 1.1 mm, especially at least 1 ,3 mm, e. g. in the range of 1.0 to 20 mm, in particular 1 ,1 to 18 mm or 1.3 to 15 mm in all directions of the space.

[0024] In the shaped bodies and similarly in the split particles, the elemental ruthenium is preferably located predominantly on or near the outer surface of the shaped body or split particles, "near the outer surface" means in particular a distance of at most 300 pm, in particular at most 250 pm and especially at most 200 pm from the outer surface of the shaped body. In other words, "on or near the outer surface” defines a space between the outer surface and a surface inside the split or the molded body that is a close to but in a certain distance from the outer surface, whereby this distance is preferably no more than 300 pm, preferably no more than 250 pm, and in particular no more than 200 pm. Thus the majority of the ruthenium atoms, in particular at least 60% of the ruthenium atoms, especially at least 80% of the ruthium atoms are located in this space within a distance of at most 300 pm, in particular at most 250 pm and especially at most 200 pm from the outer surface of the shaped body or the split particle.

[0025] M / BASFTR-4221-PC The distribution of ruthenium and other elements, such as chlorine, sodium or metals other than ruthenium or sodium in the shaped body can be determined by Electron Dispersive X-ray Spectroscopy (EDXS) or by Wavelength Dispersive X-ray Spectroscopy (WDXS) as described in the elemental section.

[0026] In a preferred groups of embodiments of the invention, the catalyst is in the form of a shaped body of porous carbon doped with elemental ruthenium, where the shaped bodies have dimensions of at least 1.0 mm, in particular at least 1.1 mm, especially at least 1 ,3 mm, e. g. in the range of 1.0 to 20 mm, in particular 1 ,1 to 18 mm or 1.3 to 15 mm in all directions of the space. In this preferred group of embodiments, the elemental ruthenium is preferably predominately located on or near the outer surface of the shaped body thereby forming a shell with a high density of ruthenium atoms near the surface of the shaped body. In particlar, the majority of the ruthenium atoms, e. g. at least 60% of the ruthenium atoms, especially at least 80% of the ruthium atoms are located within a distance of at most 300 m, in particular at most 250 pm and especially at most 200 pm from the outer surface of the shaped body.

[0027] The ruthenium catalyst of the present invention contains elemental ruthenium on a porous carbon carrier. Irrespective of its form, the heterogeneous ruthenium catalyst generally contains 1 to 10% by weight, in particular 1 .5 to 8% by weight, especially 2 to 6% by weight of ruthenium, based on the dry weight of the catalyst and calculated as elemental ruthenium.

[0028] In particular, the heterogeneous ruthenium catalyst of the present invention does not contain signifcant amount of metals different from ruthenium. In particular, the total amount of other metals, such as alkalimetals and earth alkaline metals, does not exceed more than 10% by weight, in particular less than 7% by weight, based on the total amount of ruthenium present in the catalyst. In particular, the heterogeneous ruthenium catalyst of the present invention contains less than 0.5% by weight, in particular at most 0.3% by weight of sodium, based on the dry weight of the catalyst and calculated as elemental sodium.

[0029] The amounts of ruthenium and other metals, such as alkalimetals and transition metals, can be determined by elemental analysis, e. g. by inductively coupled plasma optical emission spectrometry (ICP-OES) using an external calibration with matrix matched standards, blank subtraction, and internal standard correction. For further details we refer to the experimental part. Here, the amounts of metal are calculated on the basis of their elemental mass.

[0030] The heterogeneous ruthenium catalyst can be produced by analogy to well known methods for producing catalysts comprising elemental ruthenium on inorganic carrier materials. These methods typically comprise the treatement of the porous carbon carrier with a ruthenium compound that can be converted

[0031] M / BASFTR-4221-PC into elemental ruthenium after the treatment of the porous carbon carrier material. In particular, the ruthenium compound is converted into elemental ruthenium by subjected the treated carrier material containing the ruthenium compound to a reduction step, where the ruthenium compound is converted to elemental ruthenium.

[0032] Here and in the following, the term "porous carbon” refers to a carbon material having pores resulting in a pore volume as defined herein.

[0033] Principally a porous carbon material of any origin can be used as a carrier material for the the heterogeneous ruthenium catalyst of the present invention, as long as it ensures the total pore volume and the high contribution of pores having a pore diameter in the range of 10 to 200 nm to the total pore volume of the catalyst.

[0034] Examples of porous carbon include porous carbon produced from petrochemical feedstock, porous carbon from hard coal or peat, porous carbon from lignite, porous carbon of animal origin and porous carbon of plant origin, such as wood, bamboo, coconut shell, hereinafter also referred to as plant derived porous carbon.

[0035] The porous carbon material may be in particular an activated carbon, I. e. a carbon material which has been activated by physical processes, such treatment with CO2 or steam, or by chemical treatment, such as treatment with an acid, such as H3PO4 or ZnCl2, alkali metal halides or by alkali or by both physical activation and chemical treatment.

[0036] Generally, the porous carbon carrier has a total pore volume and a pore size distribution similar to the total pore volue and the pore size distribution of the ruthenium catalyst of the present invention. Hoever, the pore volume as well as the contribution of larger pores, I. e. pores having a diameter of 10 nm or above may be somewhat larger than in the catalyst.

[0037] Generally, the porous carbon carrier has a total pore volume in the range of 0.3 to 0.7 ml / g, in particular in the range of 0.35 to 0.6 ml / g, and pores having a pore diameter in the range of 10 to 200 nm, in particular pores having a pore diameter in the range of 10 to 100 nm, contribute at least 50%, in particular at least 60%, especially at least 70%, to the total pore volume of the heterogeneous ruthenium catalyst.

[0038] Generally, 50 to 100% or 50 to 99%, in particular 60 to 99% or 60 to 95%, especially 70 to 95% or 70 to 90% of the pore volume of the porous carbon carrier, is provided by pores having a pore diameter in the range of 10 to 200 nm.

[0039] M / BASFTR-4221-PC In particular at least 50%, more particular at least 60%, especially at least 70% of the pore volume, e. g. 50 to 100% or 50 to 99%, in particular 60 to 99% or 60 to 95%, especially 70 to 95% or 70 to 90% of the pore volume of the porous carbon carrier, is provided by pores having a pore diameter in the range of 10 to 100 nm.

[0040] In particular, the pores of the porous carbon carrier having a pore diameter of less than 10 nm contribute at most 20%, more particular at most 15%, e. g. 0 to 20% or 1 to 20%, in particular 1 to 15% or 5 to 15% to the total pore volume of porous carbon carrier.

[0041] In particular, the pores of the porous carbon carrier having a pore diameter of more than 200 nm contribute at most 20%, more particular at most 15%, e. g. 0 to 20% or 1 to 20%, in particular 1 to 15% or 5 to 15% to the total pore volume of the porous carbon carrier of the present invention.

[0042] In particular, the pores having a pore diameter of more than 100 nm contribute at most 20%, more particular at most 15%, e. g. 0 to 20% or 1 to 20%, in particular 1 to 15% or 5 to 15% to the total pore volume of the catalyst of the present invention.

[0043] All percentages mentioned in respect to pore volume of the porous carbon carrier refer to volume percentages (vol%) with respect to the total pore volume of the porous carbon carrier.

[0044] Generally, the porous carbon carrier has a BET surface of at least 150 m2 / g, in particular in the range of 150 to 400 m2 / g, especially in the range of 200 to 400 m2 / g, as determined in accordance with DIN ISO 9277 using nitrogen physisorption.

[0045] In particular, the heterogeneous ruthenium catalyst is obtainable by a process which comprises the treatment of the porous carbon carrier with an aqueous solution of a ruthenium compound, in particular with an aqueous solution of a ruthenium salt, followed by a treatment of the treated porous carbon carrier with a reducing agent, in particular with hydrogen and / or with an organic reducing agent.

[0046] Typical ruthenium compounds suitable for the treatement of the porous carbon carrier include ruthenium nitrosyl nitrate, ruthenium sulfates, such as ruthenium (III) sulfate, ruthenium halides, such as ruthenium (III) choride, and salts of ruthenic acid such as sodium ruthenate. Preferred ruthenium salts are ruthenium nitrosyl nitrate and ruthenium(lll) chloride.

[0047] M / BASFTR-4221-PC Preferably, the aqueous solution of the ruthenium compound used for the treatment of the porous carbon carrier has an acidic pH in order to avoid a precipitation of the ruthenium compound. In particular, the aqueous solution of the ruthenium compound has a pH of at most pH3, in particular at most pH 2. In particular the pH of the solution of the ruthenium compound used for the treatment of the porous carbon carrier has a pH in the range of 0.5 to 3, in particular in the range of 1 to 2.5. Here, the pH values refers to the values determined by a calibrated pH electrode at 22°C and ambient pressure, preferably in accordance with DIN 19268:2021. If necessary, the pH of the aqueous solution of the ruthenium compound can be adjusted to the aformenentioned ranges by means of an acid, in particular, selected from mineral acids, such as hydrochlorid acid, nitric acid or sulfuric acid.

[0048] The treatment of the porous carbon carrier material with the aqueous solution of the ruthenium compound can be carried out by analogy to techniques common to a skilled person. Typically, the porous carbon carrier is impregnated or soaked, respectively, by the aqueous solution of the ruthenium compound or immersed in the aqueous solution of the ruthenium compound or by combinations thereof. For example, the aqueous solution of the ruthenium compound can be sprayed onto a moving bed of the porous carbon carrier material, e. g. by means of a rotating drum coater, in order to ensure even distribution of the ruthenium compound on the carrier material. Alternatively, the porous carbon carrier material can be immersed or suspended in the aqueous solution of the ruthenium compound.

[0049] The concentration of the ruthenium compound and the amount of the solution are chosen such that the amount of ruthenium compound absorbed by the porous carbon carrier corresponds to the intended amount of elemental ruthenium on the porous carbon carrier in the final catalyst. The necessary amounts of the solution of the ruthenium compound and the concentratons can be determined by routine and estimated from the absorption capacity of the porous carbon carrier material for aqueous solutions.

[0050] The treatment of the porous carbon carrier material with the aqueous solution of the ruthenium compound is typically carried out at a temperature in the range of 20°C up to the boiling of the aqueous solution and typcially at temperatures in the range of 40 to 99 °C, especially in the range of 50 to 95°C.

[0051] As mentioned before, the treatment of the porous carbon carrier is preferably carried out with an acidic aqueous solution of the ruthenium compound, in partiuclar a ruthenium salt, to avoid a precipitation of the ruthenium compound that may cause a clogging of the ruthenium compound in the pores of the carrier material.

[0052] It has also been found to be advantageous to carry out a subsequent treatment of the treated porous carbon carrier with a base, in particular with an inorganic base, in order to fix the ruthenium compound

[0053] M / BASFTR-4221-PC absorbed in the pores of the porous carbon carrier material. For example, the porous carbon carrier previously treated with the acidic solution of the ruthenium compound is subsequently treated with an aqueous solution of a base, in particular an inorganic base. Alternatively, the porous carbon carrier can first be suspended in an acidic solution of the ruthenium compound and, after a certain time, e. g. after 10 to 240 minuntes, the pH value of the aqueous solution is raised to a neutral or basic pH value of at least pH 6, e. g. to pH 6 to 11 by adding a base, in particular by the additon of an aqueous solution of an inorganic base, to the suspension of the porous carbon carrier in the aqueous solution of the ruthenium compound.

[0054] Suitable bases for this purpose are in particular inorganic bases, such as alkalimetal carbononates, alkalimetal hydrogencarboates and alkalimetal hydroxides, such as sodium carbonate, sodium bicarbonate or sodium hydroxide.

[0055] Here and in the following the term "alkalimetal” refers to lithium, sodium, potassium, rubidium and cesium, in particular to soidum and potassium.

[0056] The treatment with the base is typically carried out at a temperature in the range of 20°C up 110°C and typcially at temperatures in the range of 40 to 100 °C, especially in the range of 50 to 95°C.

[0057] Subsequent to the treatment of the porous carbon carrier with the ruthenium compound and after the optional treatment with the base, the treated porous carbon carrier is subjected to a reducing step to convert the ruthenium compound contained in the treated carrier into elemental ruthenium. In the reducing step the porous carbon carrier that has been previously treated with the ruthenium compound and optionally with a base is treated with a reducing agent suitable for reducing the ruthenium compound to elemental ruthenium. Suitable reducing agents include in particular hydrogen or organic reducing agents, in particular organic reducing agents that during the reduction of the ruthenium compound to elemental ruthenium are converted to carbon dioxide. A particular suitable organic reducing agent is selected from formic acid and the salts thereof, in particular the alkalimetal salts of formic acid, especially sodium formate.

[0058] In a preferred group of embodiments, the reducing step for obtaining the ruthenium catalyst used in the hydrogenation alkyl levulinate to gamma valerolactone comprises the reduction of the treated porous carbon carrier with an alkalimetal formate, such as sodium formate, in the presence of a base. In particular, the base is an inorganic base as mentioned above, which is in particular selected from the group consisting of alkalimetal carbononates, alkalimetal hydrogencarboates and alkalimetal hydroxides, such as sodium carbonate, sodium bicarbonate or sodium hydroxide.

[0059] M / BASFTR-4221-PC In particular, the reduction with formic acid or the salt thereof is carried out at a pH of at least pH 9, more particularly at least pH 10. For this, the treated porous carbon carrier is preferably treated with an aqueous solution of formic acid or a salt thereof at a pH of at least pH 9, in particular at least pH 10, e. g. pH 9 to 13, especially pH 10 to 12. For example, the treated porous carbon carrier can be treated with an aqueous solution of an alkalimetal formate having pH of at least pH 9, in particular at least pH 10, e. g. pH 9 to 13, especially pH 10 to 12 or first with an aqueous solution of formic acid or sodium formate having preferably a pH in the range of 6 to 9 followed by a treatment under alkaline conditions, e. g. with an aqueous solution of the base at having pH of at least pH 9, in particular at least pH 10, e. g. pH 9 to 13, especially pH 10 to 12. Preferably, the reduction with an alkalimetal formate, such as sodium formate, in the presence of a base is carried out at a temperature of at least 60°C, in particular at least 80°C, e. g. in the range of 80 to 100°C. The time required for the reduction of the ruthenium compound with formic acid or a formate salt will depend on the temperature and can be determined by routine. The time required is typically in the range of 10 to 240 minutes. Typically, the treated and reduced catalyst is washed with water, in particular with deionized water to remove halogen.

[0060] In another preferred group of embodiments, the reducing step for obtaining the ruthenium catalyst used in the hydrogenation alkyl levulinate to gamma valerolactone comprises the reduction of the treated porous carbon carrier with hydrogen. Preferably, the reduction with an hydrogen is carried out by passing a stream of hydrogen of a mixture of hydrogen and nitrogen containing in particular 2 to 20 vol.-% of H2, through the treated porous carbon carrier material at a temperature of at least 120°C, in particular at a temperature in the range of 140 to 240°C. The time required for the reduction of the ruthenium compound with hydrogen will depend on the temperature and can be determined by routine. The time required is typically in the range of 1 to 10 h.

[0061] Of course, it is also possible to reduce the ruthenium compound on the treated porous carbon carrier material by a combination of the reduction with formic acid or salt thereof and a reduction with hydrogen. In particular, the treated porous carbon carrier material can be first subjected to a reduction with formic acid or salt thereof followed by a reduction with hydrogen.

[0062] It is assumed that, in the case of carbon shaped bodies made from the porous carbon material according to the invention, this method leads to a localization of the ruthenium near the surface, in particular if the optional treatment with the base is carried out by immersing the still moist shaped body, which has been impregnated with the aqueous ruthenium salt solution, in an aqueous solution of the base.

[0063] M / BASFTR-4221-PC The ruthenium catalyst containing elemental ruthenium on an porous carbon carrier, in particular the ruthenium catalyst, which is obtainable by the process described herein, is particularly useful for the hydrogenation of levulinic acid or alkyl levulinate, respectively, in particular methyl levulinate or ethyl levulinate, with hydrogen to obtain gamma valerolactone.

[0064] Preferably, the catalyst of the present invention is used for the hydrogenation of alkyl levulinate to obtain gamma valerolactone and the alkanol from the alkyl portion of alkyl levulinate. Suitable alkyl levulinates are C1-C4 alkyl levulinates and in particular methyl levulinate and ethyl levulinate. Particularly suitable is ethyl levulinate.

[0065] According to the invention levulinic acid or an alkyl levulinate are hydrogenated with elemental hydrogen (H2) in the presence of the heterogeneous ruthenium catalyst of the present invention.

[0066] The hydrogenation of levulinic acid or alkyl levulinate, respectively, in particular of methyl levulinate or of ethyl levulinate, with hydrogen to obtain gamma valerolactone can be carried out by analogy to the hydrogenation of organic ketones with elemental hydrogen in the presence of a supported transition metal catalyst containing a transition metal on a carrier material.

[0067] To this end, the levulinic acid or alkyl levulinate, respectively, in particular the methyl levulinate or the ethyl levulinate, can be subjected to the hydrogenation in the form of liquid phase or gas phase, preferably in the form of liquid phase. For this, the levulinic acid or the alkyl levulinate, respectively, is brought into contact with the ruthenium catalyst in the presence of hydrogen.

[0068] The hydrogenation can be designed to take place either continuously or else batchwise, preference being given here to the continuous design of the process.

[0069] In a continuous process, the liquid phase, a liquid stream of levulinic acid and / or alkyl levulinate, in particular the methyl levulinate or the ethyl levulinate, can by way of example be passed over a fluidized bed of ruthenium catalyst (fluidized bed method) or can be passed over a fixed bed of ruthenium catalyst (fixed bed method). In a batchwise design is also possible to carry out the hydrogenation in a suspension of the ruthenium catalyst in a liquid phase containing the levulinic acid or the alkyl levulinate, such as methyl levulinate or ethyl levulinate, in particular in a liquid phase which essentially consists of the alkyl levulinate, such as methyl levulinate or ethyl levulinate.

[0070] The batchwise hydrogenation can use a reaction apparatus conventionally used for this purpose, e.g. a stirred reactor.

[0071] M / BASFTR-4221-PC In the process of the invention, it is preferable that the hydrogenation of the levulinic acid or alkyl levulinate, respectively, is carried out in a fixed-bed reactor. For this, the hydrogenation is carried out continuously by passing the levulinic acid or the alkyl levulinate, in particular the methyl levulinate or the ethyl levulinate, and the hydrogen through a fixed bed of the ruthenium catalyst. It is preferable that the hydrogenation of the invention is carried out continuously in fixed-bed reactors in upflow mode or in particular in downflow mode, also referred to as sump mode. The hydrogen here can be passed over the catalyst cocurrently with the levulinic acid or alkyl levulinate, respectively, in particular methyl levulinate or ethyl levulinate, to be hydrogenated, or else in countercurrent. Preferably, the hydrogen here is passed over the catalyst cocurrently with the levulinic acid or alkyl levulinate, respectively.

[0072] Suitable apparatuses for conducting fluidized-bed-catalyst hydrogenation and fixed-bed-catalyst hydrogenation are known in the prior art, e.g. from Ullmanns Enzyklopadie der Technischen Chemie [Ullmann's Encyclopedia of Industrial Chemistry], 4thedition, volume 13, pp. 135 ff., and also from P. N. Rylander, "Hydrogenation and Dehydrogenation" in Ullmann's Encyclopedia of Industrial Chemistry, 5th edn. on CD-ROM.

[0073] Preferably, the hydrogenation of the levulinic acid and alkyl levulinate, respectively, in particular methyl levulinate or ethyl levulinate, is carried out to a degree of conversion of at least 90%, in particular at least 95%, based on the alkyl levulinate subjected to the hydrogenation.

[0074] The hydrogenation of the levulinic acid or alkyl levulinate, respectively, in particular methyl levulinate or ethyl levulinate, can be carried out in an organic solvent that is inert under the hydrogenation conditions. Suitable solvents are in particular aliphatic and alicyclic ethers, for example tetraydrofurane, dioxane, or a dialkylene glycol, such as diethylene glycol, or a mono- or dialkyl ether thereof, for example glyme, di- glyme and the like. Preferably, the hydrogenation of the levulinic acid or alkyl levulinate, respectively, is carried out in the absence of organic solvents, i. e. levulinic acid or alkyl levulinate, respectively, subjected to the hydrogenation is in essentially pure form.

[0075] Essentially in pure form is understood that the levulinic acid and the alkyl levulinate, such as methyl levulinate or ethyl levulinate, respectively, which is subjected to the hydrogenation has a purity of at least 95% by weight, in particular at least 97% by weight. Impurities may be e. g. water, alkanols, such as methanol or ethanol.

[0076] The hydrogenation of the levulinic acid and alkyl levulinate, respectively, in particular methyl levulinate or ethyl levulinate, is generally carried out at elevated hydrogen pressure. Preference is given to a hydrogen

[0077] M / BASFTR-4221-PC pressure in the range of 10 to 80 bar, in particular in the range of 15 to 70 bar, especially in the range of 20 to 60 bar.

[0078] The hydrogenation of the levulinic acid and the alkyl levulinate, respectively, in particular methyl levulinate or ethyl levulinate, is preferably carried out at a temperature in the range from 100 to 200°C, in particular at temperature in the range of 120 to 180°C.

[0079] Generally, the amount of the ruthenium catalyst of the present invention is chosen such that the amount of ruthenium is in the range of 0.02% to 2 % by weight, in particular 0.05 to 1% by weight, based on the amount of levulinic acid or alkyl levulinate, respectively. In a continuous hydrogenation the levulinic acid and the alkyl levulinate, respectively, in particular in a continuous hydrogenation of methyl levulinate or ethyl levulinate, the catalyst load, I. e. the amount of alkyl levul inate / levuli nic acid per time and amount of catalyst is typically in the range of 20 to 1000 kg / h of alkyl levulinate / levulinic acid per 1 kg of the ruthenium catalyst, in particular in the range of 40 to 400 kg / h of alkyl levulinate / levulinic acid per 1 kg of the ruthenium catalyst.

[0080] The amount of hydrogen used for the hydrogenation of the levulinic acid and alkyl levulinate, respectively, in particular the amount of hydrogen used for the hydrogenation of methyl levulinate and ethyl levulinate, respectively, is generally in the molar range 1 to 15 times of the stochiometric amount of hydrogen theoretically needed for the complete hydrogenation of the keto group in the levulinic acid or alkyl levulinate.

[0081] Preferably, the hydrogenation is carried out in such a way that at least 90%, in particular at least 95%, especially at least 97% of the levulinic acid and the alkyl levulinate, respectively, is converted, i. e. is consumed in the hydrogenation reaction. The degree of conversion can be monitored by analyzing the effluent of the reactor via gas chromatography and the reaction conditions can be adjusted accordingly.

[0082] The time required for achieving the desired conversion will depend on the conditions of the hydrogenation reaction and can be established by routine. Generally, the required reaction time is in the range of 2 to 12 h, in particular in the range of 4 to 10 h. In a continuously operated reactor, the average residence time in the hydrogenation zone containing the ruthenium catalyst of the present invention is typically in similar ranges.

[0083] As explained above, the production of gamma valerolactone via hydrogenation of levulinic acid or alkyl levulinates, such as methyl levulinate or ethyl levulinate, includes a hydrogenation of the keto carbonyl group the respective substrate, I. e. levulinic acid and alkyl levulinate, whereby 4-hydroxyvaleric acid or

[0084] M / BASFTR-4221-PC alkyl 4-hydroxyvalerate, respectively, is formed as an intermediate, which cyclizes to gamma valerolactone with formation of an alkanol as a side product.

[0085] Preferably, the process according to the invention is carried out in such a way that the 4-hydroxyvaleric acid or alkyl 4-hydroxyvalerate, respectively, formed as an intermediate makes up at most 20 mol%, in particular at most 15 mol%, based on the total amount of gamma-valerolactone and 4-hydroxyvaleric acid or alkyl 4-hydroxyvalerate, respectively, formed in the hydrogenation step. Preferably, therefore, at least 80 mol%, in particular at least 85 mol%, of the 4-hydroxyvaleric acid or alkyl 4-hydroxyvalerate, respectively, formed in the intermediate cyclize to gamma-valerolactone during the hydrogenation.

[0086] In order to further increase the yield of gamma valerolactone, the reaction mixture obtained from the hydrogenation reaction containing up to 20 mol-% of 4-hydroxyvaleric acid or alkyl 4-hydroxyvalerate, respectively, may be subjected again to a catalytic hydrogenation or to a subsequent cyclization step.

[0087] In a particular embodiment of the claimed process, a first portion P1 of the reaction mixture of the hydrogenation reaction which contains gamma valerolactone and the intermediately formed 4- hydroxyvaleric acid or alkyl 4-hydroxyvalerate, respectively, is mixed with fresh levulinic acid or alkyl levulinate, respectively, in particular with levulinic acid, methyl levulinate and / or ethyl levulinate, respectively. The thus obtained mixture is then returned into the hydrogenation in the presence of the ruthenium catalyst of the present invention. The remainder of the reaction mixture of the hydrogenation reaction which contains gamma valerolactone and the intermediately formed 4-hydroxyvaleric acid or alkyl 4-hydroxyvalerate, respectively, hereinafter also referred to the second portion P2, is subjected to a workup, in particular to a distillation, in order to purify the gamma valerolactone and separate it from the 4- hydroxyvaleric acid or alkyl 4-hydroxyvalerate, respectively. The 4-hydroxyvaleric acid or alkyl 4- hydroxyvalerate, respectively, may be subjected to a cyclization or returned into the hydrogenation reaction together with the mixture of the first portion P1 and fresh levulinic acid or alkyl levulinate, respectively. The ratio of the first portion and the second portion, hereinafter referred to as ratio P1 / P2, may vary depending on the composition of the reaction mixture of the hydrogenation reaction. Preferably the ratio P1 / P2 is in the range of 1 :2 to 80:1 and in particular in the range of 1 :1 to 50:1 on a weight basis.

[0088] In another particular embodiment of the claimed process, a first portion PT of the reaction mixture of the hydrogenation reaction which contains gamma valerolactone and the intermediately formed 4- hydroxyvaleric acid or alkyl 4-hydroxyvalerate, respectively, and non-reacted levulinic acid or alkyl levulinate, respectively, is mixed with fresh alkyl levulinate or levulinic acid, in particular with levulinic acid, methyl levulinate and / or ethyl levulinate, respectively. The thus obtained mixture is then returned into the hydrogenation in the presence of the ruthenium catalyst of the present invention. The remainder of the

[0089] M / BASFTR-4221-PC reaction mixture of the hydrogenation reaction which contains gamma valerolactone, the intermediately formed 4-hydroxyvaleric acid or alkyl 4-hydroxyvalerate, respectively, and non-reacted levulinic acid or alkyl levulinate, respectively, hereinafter also referred to the second portion P2', is subjected to a hydrogenation under forced reaction conditions, in particular at higher temperature and / or higher hydrogen pressure and / or lower load to drive the hydrogenation and cyclization to higher conversion, e. g. to conversion of above 95 mol-%, based on the total amount of alkyl levulinate and alkyl 4-hydroxyvalerate (or levulinic acid and 4-hydroxyvaleric acid) in the second portion P' . The ratio of the first portion and the second portion, hereinafter referred to as ratio P17P2', may vary depending on the composition of the reaction mixture of the hydrogenation reaction. Preferably the ratio P17P2’ is in the range of 1 :2 to 80:1 and in particular in the range of 1 :1 to 50:1 on a weight basis.

[0090] The final reaction product may be subjected to a fine distillation for increasing the purity of the gamma valerolactone.

[0091] In the following, the invention is described by way of figures and examples.

[0092] Figures 1a and 1b:

[0093] Different magnifications of a photography of the cross section area perpendicular to the longitudinal axis of the catalyst pellet from Example 3 determined by Electron Dispersive X-ray Spectroscopy (EDXS).

[0094] Figure 2:

[0095] Mass distribution of ruthenium and chlorine along the diameter of the circular cross-section perpendicular to the longitudinal axis of the catalyst pellet from Example 3 as determined by Wavelength Dispersive X- ray Spectroscopy (WDXS).

[0096] The bright areas in Figures 1a and 1b indicate that ruthenium is concentrated near the surface. This is confirmed by the distribution curve of the ruthenium concentration in Figure 2, which shows a sharply increased ruthenium concentration near the surface, whereas the ruthenium concentration inside the catalyst strand drops to values close to 0.

[0097] Experimental Section:

[0098] Abbreviations: wt-% % by weight cat catalyst

[0099] M / BASFTR-4221-PC EDXS Electron Dispersive X-ray Spectroscopy

[0100] EtLev ethyl levulinate

[0101] Ex. Example

[0102] GC Gas chromatography

[0103] GVL gamma valerolactone

[0104] Et4Hval ethyl 4-hydroxyvalerate

[0105] MIP Mercury Intrusion Porosimetry n.d. not determined vol-% volume percent

[0106] WDXS Wavelength Dispersive X-ray Spectroscopy

[0107] Analytics:

[0108] Gas Chromatography (GC)

[0109] Determination of pore volume and the pore size distribution by MIP:

[0110] Pore volume and the pore size distribution was determined by mercury intrusion porosimetry (MIP) according to DIN ISO 15901-1 :2019 DE. For this, a sample is subjected to increasing pressure using mercury as the intrusion fluid. The pressure is gradually increased, forcing the mercury to penetrate into the pores of the material. As the pressure increases, the mercury intrudes into smaller and smaller pores, allowing for the determination of the pore size distribution.

[0111] The measuring cell was filled with Hg at low pressure. The amount of mercury intruded into the sample in the range of 14.8Kpa (100pm Pore diameter) to 413MPa (3nm Pore diameter) was measured, and this data is used to calculate the pore volume, pore size distribution and pore surface assuming a cylindrical pore geometry.

[0112] Intrusion Volumes and porosity percentages are calculated with 100pm pore diameter (14.8Kpa) as starting point for the measurement.

[0113] The measurements were performed using a Micromeritics Autopore 5 system.

[0114] M / BASFTR-4221-PC Determination of BET surface:

[0115] BET was determined by in accordance with DIN ISO 9277 using the following protocol:

[0116] Samples were activated at 200°C for 12 h under vacuum. Free space was measured by He-dosing. The isotherms were measured at 77K. The pressure range for the BET fit was chosen as P / Po= 0.05-0.22. The measurements were performed using a Micromeritics ASAP2420 device.

[0117] Elemental analysis (ruthenium):

[0118] An aliquot of the sample (0.1 -0.7 g) was accurately weighed into an alumina crucible, to which 2.5 g Na2O2 were added and mixed with the sample. The crucible was inserted into a quartz vessel, covered a quartz lid and placed into a microwave muffle furnace. The muffle furnace program was initiated, which heated its contents stepwise to 720 °C (total heating cycle duration ca. 1 hour). After cooling down, the alumina crucible containing the digested sample material was added to a 250 mL beaker to which 30 mL concentrated HCI and ca. 60 mL H2O were added. The beaker was coved with a watch glass and heated over a heating plate to the boiling point for ca. 30 minutes. After total dissolution of the digested mass and cooling down to room temperature, the liquid contents of the beaker were transferred and rinsed quantitatively to a 250 ml volumetric flask and the volume completed with deionized water. Each sample was prepared in duplicate. A blank sample was prepared in the same manner.

[0119] The content of Ru was determined in the thus obtained solution via inductively coupled plasma optical emission spectrometry (ICP-OES) using an external calibration with matrix matched standards, blank subtraction, and internal standard correction. The reported result was the mean of both duplicates.

[0120] Elemental analysis (sodium):

[0121] An aliquot of the sample (0.05-0.20g) was accurately weighed into a beaker covered with a watch glass dish, to which 5 mL of H2SO4 were added, followed by 5 mL of HNO3. Next, 5 mL of a mixture of H2SO4, HNO3 and HCIO4 (1 :2:1 by volume) were added. This last step was repeated until the resulting solution was transparent and clear in appearance. Over the course of these first acid addition steps, the beaker was heated on a hot plate in a fume hood to a final temperature of approximately 300°C, adjusting the temperature stepwise according to the respective digestive reaction taking place. Finally, all acid was steamed off by tilting the watch glass dish up to not allow anymore condensation and reflux and adjusting the temperature such that the solution was gently simmering. The resulting salts were solubilized in either HCI, HNO3 or aqua regia depending on the analyte in question.

[0122] A blank sample was prepared in the same manner.

[0123] The content of Na was determined in the thus obtained solution via inductively coupled plasma optical emission spectrometry (ICP-OES) using an external calibration with matrix matched standards, blank subtraction, and internal standard correction. The reported result was the mean of both duplicates.

[0124] M / BASFTR-4221-PC Determination of the Ruthenium and other elements in the shaped carbon bodies

[0125] 1) Sample preparation

[0126] Each shaped body is placed in a gelatin capsule filled with PMMA and impregnated in a vacuum (Epovac, Struers). After curing at 60 °C overnight, the capsule is cast in ClaroCit and cut transversely to one axis of the shaped body approximately in the middle (Secotom 50) and the cut surface is wet-polished mechanically with a diamond suspension (Tegramin-20, Struers). For analysis in the SEM or electron probe microanalyzer, the section is coated with approximately 30 nm of carbon (Carbon Evaporator CED 030).

[0127] 2a) WDXS-Measurement

[0128] The distribution of Ru and Cl in the cross-section of the shaped body is analyzed using wavelength dispersive X-ray spectroscopy on the electron beam microprobe (JXA 8230, Jeol) at an acceleration voltage of 20 kV along a line scan. The line scan covers the entire cross-section and is positioned at a representative point in the backscatter image, with a step size of 20 pm at the edge (0-400 pm) and 100 pm in the center.

[0129] 2b) EDXS-Measurement

[0130] The analysis of all elements contained and their spatial distribution in the cross-section of the shaped body is performed using energy dispersive X-ray spectroscopy on a scanning electron microscope (Hitachi, SU3500, EDS detector UltraDRy 60M) at an acceleration voltage of 15 kV or 20 kV, depending on the expected elemental composition.

[0131] The following porous carbon materials were used:

[0132] Carrier 1 : A commercial activated carbon extrudate having a strand diameter of 2 mm and a BET surface about 1150 m2 / g and 35-45 vol% of pores within the diameter range of 10 to 100 nm - Commercial product: Filtercarb® ES2-K of Carbonitalia.

[0133] Carrier 2: A commercial steam activated extrudate having a diameter of of 3 mm and a BET surface area about 1100 m2 / g and less than 15 vol% of pores within the diameter range of 10 to 100 nm - Commercial product: Sorbonorit® 3 of Norit.

[0134] Carrier 3: A porous carbon pellet with a diameter of 3 mm and a BET surface area of about 320 m2 / g and 80-90 vol% of pores within the diameter range of 10 to 100 nm - Commercial product MesoC+ of SiCat.

[0135] M / BASFTR-4221-PC Carrier 4: An activated carbon pellet with a diameter of 4 mm and a BET surface area of about 1100 m2 / g and less than 25 vol% of pores within the diameter range of 10 to 100 nm - Commercial product Super- sorbon C-IV spezial of Donau Carbon GmbH.

[0136] Carrier 5: A strand of porous carbon with hexalobal cross section having a diameter of about 5 mm and having a central hole with a diameter, of 1 mm. The strand has a BET surface area of about 320 m2 / g with 80-90 vol% of pores within the diameter range of 10 to 100 nm - Commercial product MesoC+ of SiCat.

[0137] A Production of catalysts

[0138] Example 1 : 5wt% Ru (target loading) on Carrier 1

[0139] (a) 50g of the carrier 1 were placed in a 250mL pear-shaped flask (with four indentations for better mixing).

[0140] (b) In a beaker the appropriate amount of a ruthenium(lll) chloride solution (target loading 5wt%) was diluted with distilled water to a volume corresponding to approximately 95% of the water absorption of the carrier (the water absorption corresponds approximately to the pore volume).

[0141] (c) The ruthenium chloride solution was then sprayed onto the carrier within the slowly rotating pear- shaped flask over a period of 30 minutes using a spray lance in a rotary evaporator modified for this purpose.

[0142] (d) The sprayed carrier was then kept rotating in the apparatus for one hour.

[0143] (e) In another beaker, a diluted sodium formate solution was prepared by mixing about 6g sodium formate in about 21g distilled water.

[0144] (f) In another beaker, a 30% NaOH solution was prepared by mixing NaOH with distilled water.

[0145] (g) 750mL distilled water was placed in a 1L HWS vessel (double-jacketed container) and adjusted to a pH value of 10 using the NaOH solution from step (f). The intermediate obtained in step (d) was then added.

[0146] (h) The suspension was then heated to 93°C in the double-jacketed HWS vessel and stirred for 45 minutes (40rpm).

[0147] (I) Then the sodium formate solution prepared in step (e) was slowly dripped into the catalyst suspension over a period of 15 minutes while stirring.

[0148] (j) The temperature was increased to 95°C and hold for 30 minutes.

[0149] (k) Afterwards the suspension was allowed to cool and filtered using a Buchner funnel.

[0150] (l) The obtained filter cake was washed with distilled water until the filtrate was chloride-free.

[0151] (m) The product was packed in a moist state and its residual moisture was determined.

[0152] M / BASFTR-4221-PC Example 2: 5wt% Ru on Carrier 1, reduced with hydrogen and then passivated (reference example)

[0153] (a) 50g of the carrier 1 were placed in a 250mL pear-shaped flask (with four indentations for better mixing).

[0154] (b) In a beaker the appropriate amount of a ruthenium(lll) chloride solution (target loading 5wt%) was diluted with distilled water to a volume corresponding to approximately 95% of the water absorption of the carrier (the water absorption corresponds approximately to the pore volume).

[0155] (c) The ruthenium chloride solution was then sprayed onto the carrier within the slowly rotating pear- shaped flask over a period of 30 minutes using a spray lance in a rotary evaporator modified for this purpose.

[0156] (d) The sprayed carrier was then kept rotating in the apparatus for one hour.

[0157] (e) In another beaker, a 30% NaOH solution was prepared by mixing NaOH with distilled water.

[0158] (f) 750mL distilled water was placed in a 1L HWS vessel (double-jacketed container) and adjusted to a pH value of 10 using the NaOH solution from step (e). The intermediate obtained in step (d) was then added.

[0159] (g) The suspension was then heated to 93°C in the double-jacketed HWS vessel and stirred for 45 minutes (40rpm).

[0160] (h) Afterwards the suspension was allowed to cool and filtered using a Buchner funnel.

[0161] (i) The wet catalyst was placed in a rotary flask oven and dried by overflowing with nitrogen (95 mL / h) at 80°C.

[0162] (j) Then the temperature was increased to 180°C (2K / min) and the gas phase was switched to 5% hydrogen in nitrogen. Under these conditions the catalyst was reduced for 5h.

[0163] (k) The reduced catalyst was allowed to cool to room temperature under 5% hydrogen in nitrogen and then passivated using 2% air in nitrogen for 30 minutes.

[0164] (l) Afterwards the dry product was packed.

[0165] Example 3: 5wt% Ru (target loading) on carrier 2 (reference example)

[0166] (a) 50g of the carrier 2 were placed in a 250mL pear-shaped flask (with four indentations for better mixing).

[0167] (b) In a beaker the appropriate amount of a ruthenium(lll) chloride solution (target loading 5wt%) was diluted with distilled water to a volume corresponding to approximately 95% of the water absorption of the carrier (the water absorption corresponds approximately to the pore volume).

[0168] (c) The ruthenium chloride solution was then sprayed onto the carrier within the slowly rotating pear- shaped flask over a period of 30 minutes using a spray lance in a rotary evaporator modified for this purpose.

[0169] M / BASFTR-4221-PC (d) The sprayed carrier was then kept rotating in the apparatus for one hour.

[0170] (e) In another beaker, a diluted sodium formate solution was prepared by mixing about 6g sodium formate in about 21g distilled water.

[0171] (f) In another beaker, a 30% NaOH solution was prepared by mixing NaOH with distilled water.

[0172] (g) 750mL distilled water was placed in a 1L HWS vessel (double-jacketed container) and adjusted to a pH value of 10 using the NaOH solution from step (f). The intermediate obtained in step (d) was then added.

[0173] (h) The suspension was then heated to 93°C in the double-jacketed HWS vessel and stirred for 45 minutes (40 rpm).

[0174] (I) Then the sodium formate solution prepared in step (e) was slowly dripped into the catalyst suspension over a period of 15 minutes while stirring.

[0175] (j) The temperature was increased to 95°C and hold for 30 minutes.

[0176] (k) Afterwards the suspension was allowed to cool and filtered using a Buchner funnel.

[0177] (l) The obtained filter cake was washed with distilled water until the filtrate was chloride-free.

[0178] (m) The product was packed in a moist state and its residual moisture was determined.

[0179] Example 4: 5wt% Ru (target value) on Carrier 3 (according to the invention)

[0180] (a) 50g of the carrier 3 were placed in a 250mL pear-shaped flask (with four indentations for better mixing).

[0181] (b) In a beaker the appropriate amount of a ruthenium(lll) chloride solution (target loading 5wt%) was diluted with distilled water to a volume corresponding to approximately 95% of the water absorption of the carrier (the water absorption of carrier 3 is 0.40 ml / g).

[0182] (c) The ruthenium chloride solution was then sprayed onto the carrier within the slowly rotating pear- shaped flask over a period of 30 minutes using a spray lance in a rotary evaporator modified for this purpose.

[0183] (d) The sprayed carrier was then kept rotating in the apparatus for one hour.

[0184] (e) In another beaker, a diluted sodium formate solution was prepared by mixing about 6g sodium formate in about 21g distilled water.

[0185] (f) In another beaker, a 30% NaOH solution was prepared by mixing NaOH with distilled water.

[0186] (g) 750mL distilled water was placed in a 1L HWS vessel (double-jacketed container) and adjusted to a pH value of 10 using the NaOH solution from step (f). The intermediate obtained in step (d) was then added.

[0187] (h) The suspension was then heated to 93°C in the double-jacketed HWS vessel and stirred for 45 minutes (40rpm).

[0188] M / BASFTR-4221-PC (i) Then the sodium formate solution prepared in step (e) was slowly dripped into the catalyst suspension over a period of 15 minutes while stirring.

[0189] (j) The temperature was increased to 95°C and hold for 30 minutes.

[0190] (k) Afterwards the suspension was allowed to cool and filtered using a Buchner funnel.

[0191] (l) The obtained filter cake was washed with distilled water until the filtrate was chloride-free.

[0192] (m) The product was packed in a moist state and its residual moisture was determined.

[0193] Example 5: 5wt% Ru on Carrier 4

[0194] (a) 50g of the carrier Supersorbon IV were placed in a 250mL pear-shaped flask (with four indentations for better mixing).

[0195] (b) In a beaker the appropriate amount of a ruthenium(lll) chloride solution (target loading 5wt%) was diluted with distilled water to a volume corresponding to approximately 95% of the water absorption of the carrier (the water absorption corresponds approximately to the pore volume).

[0196] (c) The ruthenium chloride solution was then sprayed onto the carrier within the slowly rotating pear- shaped flask over a period of 30 minutes using a spray lance in a rotary evaporator modified for this purpose.

[0197] (d) The sprayed carrier was then kept rotating in the apparatus for one hour.

[0198] (e) In another beaker, a diluted sodium formate solution was prepared by mixing about 6g sodium formate in about 21g distilled water.

[0199] (f) In another beaker, a 30% NaOH solution was prepared by mixing NaOH with distilled water.

[0200] (g) 750mL distilled water was placed in a 1L HWS vessel (double-jacketed container) and adjusted to a pH value of 10 using the NaOH solution from step (f). The intermediate obtained in step (d) was then added.

[0201] (h) The suspension was then heated to 93°C in the double-jacketed HWS vessel and stirred for 45 minutes (40rpm).

[0202] (I) Then the sodium formate solution prepared in step (e) was slowly dripped into the catalyst suspension over a period of 15 minutes while stirring.

[0203] (j) The temperature was increased to 95°C and hold for 30 minutes.

[0204] (k) Afterwards the suspension was allowed to cool and filtered using a Buchner funnel.

[0205] (l) The obtained filter cake was washed with distilled water until the filtrate was chloride-free.

[0206] (m) The product was packed in a moist state and its residual moisture was determined.

[0207] Example 6: 5wt% Ru (target loading) on Carrier 5

[0208] The catalyst of example 6 was prepared by analogy to the protocol of example 4 using carrier 5 instead of carrier 3.

[0209] M / BASFTR-4221-PC Table 1 : Properties of the catalysts

[0210] 2) % pores having a diameter in the range of 10 to 100 nm, determined by MIP

[0211] B Hydrogenation in autoclave (batch operation)

[0212] The hydrogenation of alkyl levulinate was carried out in a 100 ml autoclave equipped with a stirrer. 40 g ethyl levulinate and 4 g of the respective catalyst were added to the autoclave (split in the catalyst basket, powder without catalyst basket). The reaction mixture was then purged with nitrogen. Thereafter, hydrogen was pressurized to approx. 10 bar, the stirrer speed was set to 1000 rpm and the reaction mixture was heated to 180°C. After reaching the reaction temperature, hydrogen was pressurized to 40 bar and the pressure was maintained at 40 bar by adding hydrogen gas. After 6 h the heating was switched off and the autoclave was allowed to cool to 22°C. Samples were taken after 2 h, 4 h and after cooling and analyzed by GC. The results are summarized in table 2.

[0213] Table 2:

[0214] 1) reference examples, not according to the invention

[0215] 2) inventive example

[0216] 3) % GVL, Et4H Vai or EtLev in the product, determined by GC and given as area %

[0217] M / BASFTR-4221-PC

Claims

Claims1 . A heterogeneous ruthenium catalyst, which comprises elemental ruthenium supported on porous carbon carrier, where the catalyst has a total pore volume in the range of 0.3 to 0.6 ml / g and where pores having a pore diameter in the range of 10 to 200 nm contribute at least 50% to the total pore volume, where the pore volume and the pore diameter is determined by mercury porosimetry in accordance with DIN ISO 15901 -1 :2019 DE.

2. A process for the production of gamma-valerlactone, which comprises a hydrogenation of levulinic acid or an alkyl levulinate with hydrogen the presence of a heterogeneous ruthenium catalyst, which comprises elemental ruthenium supported on the porous carbon carrier, where the catalyst has a total pore volume in the range of 0.3 to 0.6 ml / g and where pores having a pore diameter in the range of 10 to 200 nm contribute at least 50% to the total pore volume, where the pore volume and the pore diameter is determined by mercury porosimetry in accordance with DIN ISO 15901- 1 :2019 DE.

3. The catalyst of claim 1 or the process of claim 2, where pores having a pore diameter of less than 10 nm contribute at most 15% to the total pore volume of the catalyst.

4. The catalyst of claim 1 or the process of claim 2, where pores having a pore diameter of more than 200 nm contribute at most 15% to the total pore volume of the catalyst.

5. The catalyst or process of any one of the preceding claims, where pores having a pore diameter in the range of 10 to 200 nm contribute to the total pore volume in an amount of 0.2 to 0.6 ml / g.

6. The catalyst or process of any one of the preceding claims, where the heterogeneous ruthenium catalyst has a BET surface in the range of 150 to 400 m2 / g, as determined in accordance with DIN ISO 9277 using nitrogen physisorption.

7. The catalyst or process of any one of the preceding claims, where the heterogeneous ruthenium catalyst contains 0.5 to 8% by weight, in particular 1 to 5% by weight of ruthenium, based on the dry weight of the catalyst and calculated as elemental ruthenium.

8. The catalyst or process of any one of the preceding claims, where the heterogeneous ruthenium catalyst contains less than 0.5% by weight, in particular at most 0.3% by weight of sodium, basedM / BASFTR-4221-PCon the dry weight of the catalyst and calculated as elemental sodium.

9. The catalyst or process of any one of the preceding claims, which is in the form of a shaped body of the porous carbon carrier doped with elemental ruthenium, where the shaped body has in particular dimensions of at least 1 .0 mm, e. g. in the range of 1 .0 to 20 mm in all directions of the space.

10. The catalyst or process of any one of the preceding claims, where the elemental ruthenium is predominately located on or near the outer surface of the shaped body.11 . The catalyst or process of claim 10, where at least 60% by weight of the elemental ruthenium, based on the total weight of elemental ruthenium is located within a distance of at most 300 pm, in particular at most 250 pm and especially at most 200 pm from the outer surface of the shaped body.

12. The catalyst or process of any one of the preceding claims, where the heterogeneous ruthenium catalyst is obtainable by a process comprising the treatment of an porous carbon carrier with an aqueous solution of a ruthenium salt followed by a treatment of the impregnated porous carbon carrier with a reducing agent.

13. The catalyst or process of claim 12, where the reducing agent is hydrogen.

14. The catalyst or process of claim 12, where the reducing agent is formic acid or a salt thereof.

15. The process of any one of claims 2 to 14, where an alkyl levulinate is subjected to the hydrogenation.

16. The process of claim 15, where the alkyl levulinate is methyl levulinate or ethyl levulinate.

17. The process of claim any one of claims 2 to 16, which is carried out in such a way that at least 90% of the levulinic acid and alkyl levulinate, respectively, subjected to the hydrogenation is consumed.

18. The process of any one of claims 2 to 17, where the hydrogenation is carried out such that the levulinic acid and the alkyl levulinate, respectively, are in the liquid state.

19. The process of any one of claims 2 to 18, where the hydrogenation is carried at a temperature in the range of 100 to 200°C.M / BASFTR-4221-PC20. The process of any one of claims 2 to 19, where the hydrogenation is carried at a hydrogen pressure in the range of 10 to 60 bar. 21 . The process of any one of claims 2 to 20, where the hydrogenation is carried out continuously by passing the levulinic aicd or the alkyl levulinate, respectively, and the hydrogen through a fixed bed of the ruthenium catalyst.M / BASFTR-4221-PC

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