ES2642143B1 - Catalytic process for depolymerization of lignin - Google Patents

Abstract

Catalytic process for the depolymerization of lignin. # The invention relates to a catalytic process for depolymerization of lignin, which employs a catalyst consisting of a transition metal and a support selected from the list consisting of nanoparticles of metal oxides, a one-dimensional structure and metal oxide nanoparticles supported in a one-dimensional structure. Furthermore, the invention refers to said catalyst and the use of said catalyst for depolymerization of lignin.

Description

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Catalytic process for depolymerization of lignin DESCRIPTION

The invention relates to a catalytic process for the depolymerization of lignin, through the use of a catalyst consisting of a transition metal and a support selected from those in the list consisting of nanoparticles based on metal oxides, a one-dimensional structure and nanoparticles based on metal oxides and supported in a one-dimensional structure. Furthermore, the invention relates to said catalyst and the use thereof for depolymerization of lignin.

STATE OF ART

Lignin is one of the main components of all vascular plants and the second most abundant natural polymer. Lignin can be processed by biological, thermochemical or catalytic pathways.

The main disadvantages of the biological conversion are the slow kinetics of the metabolic processes and the complexity of the process operation, since the reaction conditions must be carefully controlled to avoid the inactivation of the microorganisms. On the other hand, in thermochemical routes, thermal energy is used to depolymerize the lignin structure in light, liquid and solid gases, for later use in the production of fuels and energy. Unfortunately, these processes involve reactions by free radicals, which makes controlling the selectivity of the depolymerization process complicated. By contrast, chemical depolymerization offers high conversion rates, greater selectivity, robust operation and easier scalability. This improvement process can be carried out in a cascade process, in which it is possible to purify, depolymerize and convert the lignin fragments into fuels and other chemicals.

DESCRIPTION OF THE INVENTION

The present invention discloses a catalytic route that manages to depolymerize lignin by selectively breaking specific bonds at high speeds and generates oligomers and monomers, which can be separated to produce compounds.

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aromatic or transformed into fuels and intermediates for the synthesis of chemical products.

Therefore, a first aspect of the present invention relates to a process for the depolymerization of lignin, where the process comprises at least one stage a) of contacting a lignin current with a catalyst consisting of a supported transition metal,

where the support selected from the list consisting of:

• metal oxide nanoparticles

• a one-dimensional structure and

• nanoparticles of metal oxides supported in a one-dimensional structure

and said step is carried out in the presence of

• a reducing agent; Y

• a solvent selected from the list consisting of water, ethanol, methanol, propanol, butanol, decalin, benzene, toluene, xylene, cyclohexane, gasoline, diesel and combinations thereof.

The term "lignin current" refers here to a current comprising lignin. For example, this lignin current is obtained from the cellulose ethanol production process vinasses.

In a preferred embodiment, the transition metal is selected from the list consisting of Sn, Ga, Mg, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo , Ru, Rh, Pd, Ag, Cd, La, Hf, Ta, W, Re, Os, Go, Pt, Au and combination thereof. Preferably, the transition metal is selected from the list consisting of Ni, Ru, Pd, Fe, Mo, Co, Cu, Fe and combination thereof. More preferably, the transition metal is selected from Ru, Ni, and a combination thereof.

In another preferred embodiment, the transition metal is in the form of a metal aggregate with a particle size between 1 and 100 nm, preferably between 2 and 50 nm, whose composition has been mentioned above.

A further embodiment of the present invention relates to a process for depolymerization of lignin, where the metal oxide nanoparticles are

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selected from the list consisting of SiO2, TiO2, V2O5, Cr2O3, MnO2, MgO, Fe2O3, FeO, CoO, ZnO, Y2O3, ZrO2, Nb2O5, CdO, La2O3, SnO2, HfO2, Ta2O5, ^ VO3, Re2O7, Re2O7

Al2O3, CeO2, Cs2O and combination thereof. Preferably, the metal oxide nanoparticles are selected from the list consisting of TiO2, V2O5, Cr2O3, MnO2, ZrO2, CeO2 and combination thereof. More preferably, the metal oxide nanoparticles are selected from the list consisting of TiO2, V2O5, MnO2, ZrO2, CeO2 and combination thereof.

The term "one-dimensional structure" refers here to filaments, wires, fibers, hairs, rods, ribbons and tubes whose lateral dimensions are within the range of 50 to 5000 nm.

In a preferred embodiment, the one-dimensional structure is selected from the list consisting of C nanotubes, TiO2 nanotubes, V2O5 nanotubes, MnO2 nanotubes, ZrO2 nanotubes, carbon fibers, graphene sheets and combination thereof.

Preferably, the carbon one-dimensional structure is C nanotubes, that is, carbon nanotubes. More preferably, the carbon nanotubes have an aspect ratio length: diameter (L / D) between 5 and 2000 and lengths between 50 and 5000 nm.

In a preferred embodiment, the one-dimensional structure comprises magnetic nanoparticles on its surface.

Preferably, the magnetic nanoparticles are Fe (II I) oxide nanoparticles such as Fe2O3, NiOFe2O3, CuOFe2O3, MgOFe2O3 and a combination thereof; These magnetic nanoparticles facilitate the extraction and separation of the catalyst from the reaction mixture after reaction, by using an electromagnetic separation unit.

In a preferred embodiment, the percentage by weight of the magnetic nanoparticles of Fe (III) oxides in the one-dimensional structure is in the range of 5 to 60% by mass. Preferably, the percentage by weight of the magnetic nanoparticles of Fe (III) oxides in the one-dimensional structure is between 10% and 50%, and more preferably between 20% and 40%.

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As mentioned above, step a) of the lignin depolymerization process is carried out in the presence of

• a reducing agent; Y

• a solvent selected from the list consisting of water, ethanol, methanol, propanol, butanol, decalin, benzene, toluene, xylene, cyclohexane, gasoline, diesel and combinations thereof.

In a preferred embodiment, the reducing agent is selected from the list consisting of hydrogen, formic acid, ethanol, methanol and combinations thereof.

In another preferred embodiment, step a) is carried out at pressures between 10 bar and 100 bar and temperatures between 150 ° C and 400 ° C.

Preferably, step a) is carried out at pressures between 10 bar and 70 bar, preferably at pressures between 30 bar and 60 bar and, more preferably between 40 bar and 60 bar.

Preferably, step a) is carried out at temperatures between 150 ° C and 300 ° C, preferably at temperatures between 150 ° C and 250 ° C, and more preferably between 180 ° C and 200 ° C.

A further embodiment of the present invention provides a process for depolymerization of lignin, where the lignin current previously used in step a) has been previously purified.

In another preferred embodiment, the pH of the lignin current of step a) is between 4 and 8, preferably between 4 and 6.

In addition, another preferred embodiment of the present invention relates to the above process which further comprises a step b) of catalyst recovery. Preferably, the recovery of the catalyst is carried out by filtration, for example using a hydrocyclone or a particulate filter. In a further embodiment, step b) is followed by a step b ’) comprising the recovery of the catalyst by applying a magnetic field between 0.1 Tesla and 5 Tesla, said catalyst comprising a one-dimensional structure comprising nanoparticles

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magnetic on its surface. For example, an electromagnetic cyclone can be used.

In another preferred embodiment, the mentioned process further comprises a step c) of purifying the current obtained in step b) or in step b ') by separating a stream consisting of a solvent and a non-depolymerized lignin stream of a stream consisting of aromatic compounds derived from lignin. For example, this separation is a distillation of the current obtained in stage b) or in stage b ’).

Another aspect of the present invention relates to the process of obtaining ethanol and / or butanol comprising

• steps a) to c) of depolymerization of lignin according to the process described above; Y

• a stage d) of contact between genetically modified microorganisms and the aromatic compounds derived from lignin obtained during stage c).

Preferably, genetically modified microorganisms are selected from the list consisting of basidiomycetes fungi, chrysosporium phanerochaete, and streptomyces spp.

A third aspect of the invention relates to a catalyst consisting of a transition metal and a support, where the support is formed by nanoparticles of metal oxides supported in a one-dimensional structure.

In a preferred embodiment, the transition metal is chosen from a list consisting of Sn, Ga, Mg, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo , Ru, Rh, Pd, Ag, Cd, La, Hf, Ta, W, Re, Os, Go, Pt, Au and combination thereof. Preferably, the transition metal is selected from the list consisting of Ni, Ru, Pd, Fe, Mo, Co, Cu, Fe and combination thereof. More preferably, the transition metal is selected from Ru, Ni and and combination thereof.

In another preferred embodiment, the transition metal is in the form of a metal aggregate with a particle size between 1 and 100 nm, preferably

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between 2 and 50 nm, and more preferably between 2 and 5 nm, whose composition is mentioned above.

A further embodiment of the catalyst refers to metal oxide nanoparticles selected from the list consisting of SiO2, TiO2, V2O5, Cr2O3, MnO2, MgO, Fe2O3, FeO, CoO, ZnO, Y2O3, ZrO2, Nb2O5, CdO, La2O3, SnO2 , HfO2, Ta2O5,

WO3, Re2O7, Al2O3, CeO2, Cs2O and combination thereof. Preferably, the metal oxide nanoparticles are selected from the list consisting of TiO2, V2O5, Cr2O3, MnO2, ZrO2, CeO2 and combination thereof. More preferably, the metal oxide nanoparticles are selected from the list consisting of TiO2, V2O5, MnO2, ZrO2, CeO2 and combination thereof.

Another embodiment of the catalyst refers to a one-dimensional structure, selected from the list consisting of C nanotubes, TiO2 nanotubes, V2O5 nanotubes, MnO2 nanotubes, ZrO2 nanotubes, carbon fibers, graphene sheets and combination thereof .

Preferably, the one-dimensional structure are carbon nanotubes. More preferably, the carbon nanotubes have a length: diameter (L / D) aspect ratio between 5 and 2000 with lengths between 50 nm and 5000 nm.

In a preferred embodiment, the one-dimensional structure comprises magnetic nanoparticles on its surface. Preferably, the magnetic nanoparticles are Fe (III) magnetic oxide nanoparticles such as Fe2O3, NiOFe2O3, CuOFe2O3, MgOFe2O3 and a combination thereof.

In a preferred embodiment, the percentage by weight of the magnetic nanoparticles of Fe (III) oxides in the one-dimensional structure vary between 5 and 60%. Preferably, the percentage by weight of the nanoparticles of Fe (III) oxides in the one-dimensional structure varies between 10 and 50%, more preferably between 20 and 40%.

The last aspect of the invention is related to the use of the catalyst mentioned above for the depolymerization of lignin.

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Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by a person skilled in the art to which the present invention belongs. Procedures and materials similar or equivalent to those described herein may be used in the practice of the present invention. Throughout the description and claims, the word "comprises" and its variations are not intended to exclude other technical characteristics, additives, components or stages. Objectives, advantages and additional features of the invention will be apparent to those skilled in the art after examination of the description or can be learned by the practice of the invention The following examples and drawings are provided by way of illustration and are not intended to be limiting of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 Cascade process scheme for the isolation, purification and depolymerization of lignin currents using heterogeneous catalysts.

FIG. 2 Cascade process scheme for the isolation, purification and depolymerization of lignin currents using heterogeneous catalysts.

FIG. 3 GC-MS chromatogram of the main products identified in Example 1; 1) 4-ethylphenol, 2) 2,3-dihydro-1-benzofuran, 3) 1- (2-methoxyphenyl) ethanol, 4) 2,6-dimethoxy-4- (prop-2-en-1-yl) phenol, 5) methyl (2E) -3- (4-hydroxyphenyl) prop-2-enoate.

FIG 4 Reverse correlation spectrum of 1H-13C (HSQC) measured in DMSO-d6 at 25 ° C of dried vinasse (material with lignin content) derived from cellulosic bioethanol before catalytic depolymerization.

FIG 5 Reverse correlation spectrum of 1H-13C (HSQC) measured in DMSO-d6 at 25 ° C of dried vinasse (material with lignin content) derived from cellulosic bioethanol after methanol treatment for 4 h at 200 ° C, 750 rpm and 25 bar of H2 in the absence of catalyst.

FIG. 6 GC-MS chromatogram of the main products identified in Example 2; 1) 4-ethylphenol, 2) 2,3-dihydro-1-benzofuran, 3) 1- (2-methoxyphenyl) ethanol, 4) 2,6-dimethoxy-4- (prop-2-en-1-yl) phenol, 5) methyl (2E) -3- (4-hydroxyphenyl) prop-2-enoate.

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FIG 7: Inverse correlation spectrum of 1H-13C (HSQC) measured in DMSO-d6 at 25 ° C of dry lignin derived from the production of cellulosic bioethanol after 4 h of reaction at 200 ° C, 25 bar of H2 and 750 Stirring rpm in the presence of 50 mg of a 5% Ru / ZrO2 catalyst. The initial mass of lignin was approximately 500 mg and 20 ml of methanol was used as solvent.

FIG 8: GC-MS chromatogram of the main products identified in Example 3; 1) 4-ethylphenol, 2) 2,3-dihydro-1-benzofuran, 3) 1- (2-methoxyphenyl) ethanol, 4) 2,6-dimethoxy-4- (prop-2-en-1-yl) phenol, 5) methyl (2E) -3- (4-hydroxyphenyl) prop-2-enoate.

FIG 9: GC-MS chromatogram of the main products identified in Example 4; 1) 4-ethylphenol, 2) 2,3-dihydro-1-benzofuran, 3) 1- (2-methoxyphenyl) ethanol, 4) 2,6-dimethoxy-4- (prop-2-en-1-yl) phenol, 5) methyl (2E) -3- (4-hydroxyphenyl) prop-2-enoate.

FIG 10: Inverse correlation spectrum of 1H-13C (HSQC) measured in DMSO-d6 at 25 ° C of dry lignin derived from the production of cellulosic bioethanol after 4 h of reaction at 200 ° C, 25 bar of H2 and 750 Stirring rpm in the presence of 50 mg of a 5% Ru / ZrO2 / MWCNT catalyst. The initial mass of lignin was approximately 500 mg and 20 ml of methanol was used as solvent.

EXAMPLES

A cascade process for the isolation, purification and depolymerization of lignin currents using a heterogeneous catalyst is described below.

Figure 1 shows the detailed process diagram for the isolation, purification and depolymerization of lignin currents, e.g. vinasses from the production of cellulosic bioethanol. Initially, the ligninic stream (1) is fed into the purification unit (19) operating at temperatures between 298 K and 373 K, in which an aqueous acid solution is added by the stream (6). In this purification unit (19) any cellulose and / or hemicellulose residue present in the stream (1) is solubilized, while lignin polymers precipitate selectively.

The resulting stream (2) is fed to the separation unit (20), in which the solids comprising lignin polymers are separated into the stream (7) and the liquid fraction, stream (3), is sent to the unit acid recovery (21). The

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recovery unit (21) separates any additional solid and organic material from the acid solution, obtaining a stream rich in acid (6) that is recycled to the unit (19), while the stream enriched in impurities (5) is sent to Water treatment facility. In order to keep the pH constant in the unit (19), fresh acid is added to the process through the stream (4), consisting of concentrated acid.

The lignin current (7) is fed to the unit (22) to adjust its pH and perform the final conditioning. The stream (9) can be either an aqueous solution diluted with basic pH, or a water stream with neutral pH. The stream (8) containing the liquid fraction is sent to the wastewater treatment plant, while the solid stream (10) containing the purified lignin is sent to the reactor (23) containing the catalyst. Alternatively, the lignin current produced in the unit (20) can be sent directly to the reaction unit (23) by means of the current (11), by deriving or avoiding the pH adjustment unit (22). In another alternative, the lignin current (1) can be fed directly into the reactor (23) by means of the current (18) by deriving or avoiding the units (19), (20) and (22); If the purity of the lignin current is high enough, i. and. It has a low ash and cellulose content.

The reactor (23) can be operated in a single liquid phase or in a biphasic liquid phase depending on the concentration of water in the incoming ligninic stream: streams (10), (11) and (18).

In one embodiment, the reactor (23) operates in a single phase comprising dilute water or alcohols (26), lignin macromolecules, the hydrogenation catalyst (A) and a reducing agent stream (12).

In another embodiment, the reactor (23) operates in a biphasic mode in the liquid phase, which includes aqueous phases (eg water, alcohols or mixtures thereof) and organic phases (eg aromatic compounds derived from lignin, gasoline, diesel or toluene ) with volumetric ratios of aqueous to organic phase between 0.1: 1 and 10: 1.

The lignin depolymerization product (14) is fed to the separation unit (24) that separates the solvent and the unpolymerized lignin to be

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recycled in the stream (13) of the aromatic stream derived from lignin in the stream (15).

Alternatively, the purified aromatic compounds separated in the process unit (24) are fed to the reactor (25), in which they are converted into value-added products (eg ethanol, butanol) (17) using genetically modified microorganisms to metabolize the aromatic compounds

Figure 2 shows in detail an alternative process diagram for the isolation, purification and depolymerization of lignin currents, e.g. vinasses from the production of cellulosic bioethanol using a catalyst with magnetic properties. In this process, an output current (27) from the reactor (23) reaches an electromagnetic separator (28) that recovers the catalyst by applying a magnetic field. The purified stream (30) is fed back to the reactor (23). In addition, the use of an electromagnetic separator allows the extraction of partially depolymerized lignin (stream 29) of the catalyst retained in the electromagnetic separator and the monomers (stream 31). The current (31) is fed to the process unit (24) for the subsequent fractionation of the phenolic compounds.

The most critical stage of the cascade process described by Figures 1 and 2 is the depolymerization of the lignin currents using the reactor (23), which operates in single phase.

To evaluate this critical stage the following catalysts were synthesized (see Table 1):

Sample A: 5% nanoparticles M / ZrO ?, where M = transition metal

Zirconia (ZrO2 nanoparticles) was synthesized by precipitation of zirconium hydroxide. First, 37.53 g of hydrated Zr (IV) oxynitrate were added to 405.7 ml of deionized water and the mixture was stirred for 2 h until the salt dissolved completely. An ammonium solution was then added dropwise to initiate precipitation, until a pH of 10 was reached. Once precipitated, the solid was aged at room temperature between 65 and 72 hours, controlling and adjusting the pH when necessary to ensure that the pH was maintained at 10 throughout the process. The resulting solid was filtered and washed with deionized water, until the pH of the

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wash water was equal to 7. This solid was washed 3 times with ethanol to remove additional impurities. The solid was dried in an oven for 12 h and calcined in a flask at 500 ° C for 10 h. The final mass of ZrO2 was 12.87 g.

Sample A1: the 5% Ru / ZrO2 catalyst was synthesized by excess impregnation. For this synthesis, a certain amount of the precursor salt (RuCl3) was dissolved in deionized water, in order to obtain a solution that allowed to produce a catalyst with 5% by weight of the active metal in the support. The solution was impregnated in the desired support and the catalyst was dried in an oven at 100 ° C overnight. The resulting catalyst was calcined in a muffle in an air atmosphere, with a temperature ramp of 2 hours to reach 400 ° C and then the catalyst was maintained at 400 ° C for 4h.

Sample A2: the 5% Ni / ZrO2 catalyst was synthesized following the same procedure as for the previous catalyst, but the active metal was impregnated by impregnation to incipient moisture, the precursor being used Ni (NO3) 2.

Sample B: 5% X / MWCNT, where X = transition metal or ZrO2 nanoparticles

5 g of MWCNT-MgO-Al2O3 were prepared by chemical deposition in the carbon vapor phase on a FeCo catalyst. The following precursors were dissolved in 35 ml of deionized water: 8.97 g of Mg (NO3) 2.6H2O, 31.35 mg of (NH4) aMo7O24.4H2O, 870 mg of Fe (NO3) 3.9H2O and 5.54 g of Al (NO3) 3.9 H2O The salts were mixed with 5 g of citric acid. The dried solid was calcined for 3 h at 773 K. To grow the MWCNT, 500 mg of FeCo-MgO-Al2O3 was placed inside a flow reactor heated to 773 K in a continuous flow of H2 for 30 minutes. Then, the temperature rose to 973 K in He flow for 20 minutes. Finally, a flow of C2H4 in He was fed with a volumetric ratio of 1: 3 (C2H4: He) for 10 min at 973 K to obtain MWCNT-MgO-Al2O3. Then the MgO-Al2O3 used as support was eliminated: 5 g of MWCNT-MgO-Al2O3 were treated in a 10% HF solution for 1 h and 323 k to remove the support of metal oxides (MgO and Al2O3), obtaining the MWCNT . The resulting material was washed with distilled water until it reaches a neutral pH. Then, 1 g of purified MWCNT was treated with 50 ml of nitric acid (HNO3, 16 M) under stirring for 3 h at 393 K. The resulting product was cooled to room temperature and then filtered using nylon filters with a pore size from 0.22 pm. The solids

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The recovered ones were washed repeatedly with deionized water until a pH of 7 was reached. The oxidized carbon nanotubes (MWCNT-COOH, treated with acid) were dried at 343 K overnight in a vacuum oven. Then, 1 g of MWCNT-COOH was added to a mixture of 20 ml of sulfuric acid (H2SO4, 18 M) and 300 ml of acetic anhydride ((CH3-CO) 2O), under constant stirring at 353 K. After 2 h , the reaction mixture was cooled to room temperature and the thick mixture obtained was filtered and washed with deionized water to remove any residual acid, and then dried overnight in a 343 K vacuum oven.

Sample B1: the 5% Ru / MWCNT catalyst was synthesized by the impregnation method to incipient moisture. A certain amount of the precursor salt (RuCl3) was dissolved in a mixture with a 1: 1 (v / v) ratio of methanol and deionized water, in order to obtain a solution that allows obtaining a catalyst with 5% by weight of the active metal in the support. The solution was impregnated in the desired support and then the catalyst was dried in an oven at 100 ° C overnight. Then, the calcination of the catalyst was carried out in a tubular quartz reactor, with a vertical nitrogen flow of 20 ml / min. A temperature ramp of 3 ° C / min was established to reach 400 ° C and then the catalyst was maintained at this temperature for 4 h under nitrogen flow.

Sample B2: the 5% Ni / MWCNT catalyst was synthesized following the same procedure as for the previous catalyst, but the precursor used was Ni (NO3) 2.

Sample B3: The 50% ZrO2 / MWCNT catalyst was prepared using a 70 vol zirconium propolis solution. % in propanol (C12H28O4Zr) obtained from Sigma-Aldrich to prepare an impregnation solution of the precursor in isopropanol (99.99% of Sigma-Aldrich). To impregnate 200 mg of MWCNT-purified (supplied by SouthWest NanoTechnologies), 0.49 ml of 70 vol. Zirconium isopropoxide. % in propanol were dissolved in 0.31 ml of isopropanol. The solution was impregnated by impregnation to incipient moisture in an inert atmosphere. The impregnated material was dried in an oven at 100 ° C overnight. The solids were then calcined in a piston flow reactor with a vertical nitrogen flow of 20 ml / min. A temperature ramp of 3 ° C / min was established to reach 400 ° C and then the catalyst was maintained at this temperature for 4 hours under nitrogen flow.

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Sample C: 5% M / ZrO2 / MWCNT, where M = transition metal

Sample C1: The 5% Ru / ZrO2 / MWCNT catalyst was synthesized by the method of impregnation to incipient moisture. A certain amount of the precursor salt (RuCl3) was dissolved in a certain amount of 1: 1 (v / v) mixture of methanol and water, in order to obtain a solution that allowed to obtain a catalyst with 5% by weight of the active metal in the support. The support used for this catalyst was the 50% ZrO2 / MWCNT catalyst described above. The solution was impregnated in the desired support and then the catalyst was dried in an oven at 100 ° C overnight. Then, the calcination of the catalyst was carried out in a tubular quartz reactor, with a vertical nitrogen flow of 20 ml / min. A temperature ramp of 3 ° C / min was established to reach 400 ° C, the catalyst being kept at this temperature for 4 hours under nitrogen flow.

Sample D: 5% M / ZrO2 / MWCNT- magnetic Fe2O3 nanoparticles, where M = transition metal

Sample D1: the catalyst of M / ZrO2 / MWCNT-magnetic nanoparticles of Fe2O3 with magnetic properties was synthesized according to the following steps:

The first step was the oxidation of the carbonaceous support (MWCNT) to generate oxygenated functional groups. Such functional groups should anchor the magnetic Fe2O3 nanoparticles. For the oxidation of the carbonaceous support (MWCNT), a certain amount of carbon nanotubes was added to a solution of 60% v / v of HNO3, stirring at 65 ° C for 3 hours and at 300 rpm. Then, the mixture was neutralized, first by dilution with deionized water and then slowly adding ammonium until the pH was equal to 7. The neutralized mixture was filtered with a Büchner and the solid obtained was washed with deionized water. Said solid was dried in an oven at 80 ° C overnight.

The second step was to anchor the Fe2O3 magnetic nanoparticles on the surface of the support (MWCNT) by deposition methods such as excessive impregnation and / or impregnation to incipient moisture. For the incorporation of the magnetic particles, a solution of FeN3O9.H2O was prepared first. The oxidized carbon nanotubes from the previous step were added to this solution and the mixture was kept under stirring for 3 hours and then the solution was evaporated.

Maintaining agitation The solids were recovered and dried in an oven at 100 ° C overnight. Then, the solid was heat treated at 750 ° C for 3 hours in a flow of 100 ml / min of nitrogen, to form the iron magnetic species. The solid obtained was screened and the fraction with a particle size of 5 below 100 pm was recovered for use as a magnetic support.

The third step consisted in the impregnation with ZrO2 and Ru of the MWCNT support comprising magnetic particles of Fe2O3 in the same way as with sample C1.

10 The following Table 1 summarizes the synthesis of the catalysts.

Table 1: Catalysts used in depolymerization of lignin currents

 Sample A 5% M / ZrO2 Nanoparticles

 Sample B Nanoparticles 5% X / MWCNT X = M or ZrO2 Sample C 5% M / ZrO2 / MWCNT Sample D 5% M / ZrO2 / MWCNT - magnetic nanoparticles of Fe2O3

 Sample A1 5% Ru / ZrO2 Nanoparticles

 Sample B1 5% Ru / MWCNT Sample C1 5% Ru / ZrO2 nanoparticles / MWCNT Sample D1 5% Ru / ZrO2 / MWCNT- Fe2O3 magnetic nanoparticles

 Sample A2 5% Ni / ZrO2 Nanoparticles

 Sample B2 5% Ni / MWCNT

 Sample B3 5% ZrO2 / MWCNT nanoparticles

15 In order to demonstrate the performance of the catalysts described above, a series of examples were made. Table 2 mentions the number of the example performed using the different catalysts.

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Table 2: Example number against the catalyst used

 Catalyst

 Example 1: Comparative

 Without catalyst

 Example 2

 Sample A1 5% Ru / ZrO2 Nanoparticles

 Example 3

 Sample B1 5% Ru / MWCNT

 Example 4:

 Sample C1 5% Ru / ZrO2 / MWCNT nanoparticles

 Example 5: Comparative

 Ru / C

The characterization methods used in each example were the following:

In order to identify the products obtained in each example, 1 ml of the liquid product was extracted and filtered to be analyzed by gas chromatography with a mass spectrometer (GC-MS) equipped with an HP-5 chromatographic column (Agilent) with a diameter of 0.32 pm and 30 m in length. The rest of the reaction mixture was centrifuged at 9000 rpm for 30 minutes to precipitate the dispersed solids. The liquid fraction was collected in a flask for further analysis and the solids were washed with 15 ml of a methanol: ethyl acetate mixture (2: 1) and then centrifuged again at 9000 rpm for 30 minutes. The liquid obtained after the second centrifugation was separated from the solids and added to the first collected liquid fraction. The final liquid fraction was concentrated by a rotary evaporator, removing methanol and ethyl acetate from the reaction medium and the washing process.

Catalytic and selective rupture of the C-O-C bonds of lignin was performed to depolymerize lignin effectively. Catalysts were selected for the hydrogenolysis of the C-O bonds of lignin (see Table 1) while seeking to achieve a minimum hydrogenation of the aromatic rings.

The 2D NMR spectra of lignin were analyzed to quantify the degree of depolymerization of lignin, by determining the concentration of p-O-4 bonds.

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Sample preparation for 2D NMR involved an acetalization process in a solution of acetic acid: pyridine (1: 1, v / v) stirred at room temperature for 48 hours. Then, the reaction mixture was concentrated in vacuo, the resulting residue was dissolved in DMSO, centrifuged and the supernatant (acetylated lignin) was lyophilized. The NMR spectra of the acetylated samples were performed in DMSO-d6, to avoid fractionation of the sample before NMR analysis and to increase both the solubility and the dispersion of the chemical displacement of the side chains.

Reverse correlation spectra of 1H-13C (HSQC) were measured at 25 ° C on a Bruker AVANCE III 700 MHz instrument equipped with a 5mmTCI cryogenically cooled gradient probe with inverse geometry, the proton coil closest to the sample. HSQC (heteronuclear single quantum coherence) experiments were performed using the Brukers pulse program “hsqcetgpsisp2.2” (pulsed adiabatic version) with spectrum widths of 5000 Hz (from 10 to 0 ppm) and 20843 Hz (from 165 to 0 ppm) for dimensions 1H- and 13C. The number of complex points recorded was 2048 for the 1H dimension with a recycle delay of 1.5 s. The number of transients was 64, and 256 time increments were recorded in dimension 13C in all cases. A 1 Jch of 145 Hz was used. The processing employed a typical combined Gaussian apodization in the 1H dimension and a squared cosine window apodization in the 13C dimension. Before performing the Fourier transform, the data matrices were filled with zeros up to 1024 points in dimension 13C to have a continuous series of data. The central peak of the solvent was used as internal reference (5C 39.5; 5H 2.49). Evolution times of the long range J coupling of 66 and 80 ms were used in different heteronuclear multiple link correlations (multiple heteronuclear link correlation, HMBC) for acquisition experiments. The peaks were assigned by comparison with bibliography.

The examples made are as follows:

Example 1: depolymerization of lignin without catalyst

In this experiment, 502.4 mg of lignin was placed inside the reactor (23) without catalyst. Then, 30 ml of methanol was added to the reactor before closing it and performing a leak test with N2. The reactor was purged three times with H2 to remove

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any remaining N2 and O2 present in the medium, and then it was pressurized at 25 bar with H2. The stirring speed was set at 750 rpm and the temperature was raised from room temperature to 200 ° C in 120 min. Once the desired temperature was reached, the reaction began. After 4 h of reaction the heating and stirring were turned off and the reactor was cooled in an ice bath. When the reactor temperature was below 20 ° C, the reactor was carefully depressurized.

The analysis of the samples revealed the following results: the organics recovered in the flask accounted for 242 mg. The solids recovered were weighed, obtaining 262.1 mg, which correspond to solid lignin.

The closing of the balance of matter was 100.3%, with 48.2% corresponding to lignin converted into liquid products and 52.2% into solid products

Figure 3 shows the GC-MS chromatogram obtained, in which the total area of the products obtained is 1.0 x 107 and the main products identified were: 1) 4-ethylphenol, 2) 2,3-dihydro-1- benzofuran, 3) 1- (2-methoxyphenyl) ethanol, 4) 2,6-dimethoxy-4- (prop-2-en-1-yl) phenol, 5) methyl (2E) -3- (4-hydroxyphenyl) prop-2-enoato.

Figure 4 shows the HSQC spectrum obtained for the dry vinasses of the bioethanol production process, which contains macromolecular lignin in high concentrations. In this figure it is possible to identify ferulato, p-coumarato, coumaril, guaiacil, siringil, p-O-P ’, p-O-4, p-O-5’, -CH3, and -OCH3. In addition, signals corresponding to oligosaccharides could be detected, which may be due to residual cellulose from the enzymatic hydrolysis and fermentation process. In this sample, the p-O-4 link represents about 42% of the lignin bonds, a value similar to those found in the literature.

Figure 5 shows the results of HSQC obtained for the same lignin sample after being treated in methanol for 4 h at 200 ° C, 750 rpm, and 25 bar of H2 in the absence of catalyst. Various functional groups can be identified, as well as lignin monomers such as ferulate, p-coumarate, coumaril, guaiacil, siringil, p-O-P ’, p-O-4, P-O-5’, -CH3, and -OCH3. In addition, signals corresponding to oligosaccharides could be detected, which may be due to residual cellulose from the enzymatic hydrolysis and fermentation process. In this sample the links p-O-4

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They represented 37% of the total, indicating that only 12% of the bonds degraded after this treatment.

Example 2: Depolymerization of lignin using nanoparticles of a 5% Ru / ZrO2 catalyst (Sample A1)

In this experiment 50.5 mg of 5% Ru / ZrO2 was placed inside the reactor (23) together with 500.7 mg of lignin. Then, 30 ml of methanol was added to the reactor before closing the system and performing a leak test with N2. The reactor was purged three times with H2 to remove any remaining N2 and O2 present in the medium, and then pressurized at 25 bar with H2. The stirring speed was set at 750 rpm and the temperature was raised from room temperature to 200 ° C in 120 min. Once the desired temperature was reached, the reaction began. After 4 h of reaction the heating and stirring were turned off and the reactor was cooled in an ice bath. When the reactor temperature was below 20 ° C, the reactor was carefully depressurized.

Analysis of the samples revealed the following results: organic recovered in the flask accounted for 309.7 mg. The solids recovered were weighed, obtaining 312.2 mg, corresponding to solid lignin and the catalyst.

The closing of the balance of matter was 114.2%, with 52.4% corresponding to lignin converted into liquid products and 61.9% into solid products.

Figure 6 shows the GC-MS chromatogram obtained, in which the total area of the products obtained is 1.1 x 107 and the main products identified were: 1) 4-ethylphenol, 2) 2,3-dihydro-1- benzofuran, 3) 1- (2-methoxyphenyl) ethanol, 4) 2,6-dimethoxy-4- (prop-2-en-1-yl) phenol, 5) methyl (2E) -3- (4-hydroxyphenyl) prop-2-enoato.

Figure 7 shows the results of HSQC obtained from the dry vinasses of the bioethanol production process, which contains macromolecular lignin in high concentrations, the same sample used in Example 1, after being treated in methanol for 4 h at 200 ° C, 750 rpm, and 25 bar of H2 in the presence of 5% Ru / ZrO2 catalyst nanoparticles (Sample A1). Various functional groups can be identified, as well as lignin monomers such as ferulate, p-coumarate, coumaril, guaiacil, siringil, p-O-P ’, p-O-4, p-O-5’, -CH3, and -OCH3. In addition, they could

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detect signals corresponding to oligosaccharides, which may be due to residual cellulose of enzymatic hydrolysis and fermentation process. In this sample, the p-O-4 bonds represented 25% of the total, indicating that only 60% of the bonds degraded after this treatment.

Example 3: Depolymerization of lignin using the catalyst 5% Ru / MWCNT (Sample B1)

In this experiment 50.0 mg of 5% Ru / MWCNT was placed inside the reactor (23) together with 500.0 mg of lignin. Then, 30 ml of methanol was added to the reactor before closing the system and performing a leak test with N2. The reactor was purged three times with H2 to remove any remaining N2 and O2 present in the medium, and then pressurized at 25 bar with H2. The stirring speed was set at 750 rpm and the temperature was raised from room temperature to 200 ° C in 120 min. Once the desired temperature was reached, the reaction began. After 4 h of reaction the heating and stirring were turned off and the reactor was cooled in an ice bath. When the reactor temperature was below 20 ° C, the reactor was carefully depressurized.

Analysis of the samples revealed the following results: organic recovered in the flask accounted for 260.7 mg. The solids recovered were weighed, obtaining 312.2 mg, with 52.1% of lignin converted into liquid products.

Figure 7 shows the GC-MS chromatogram obtained, in which the total area of the products obtained is 2.4 x 107 and the main products identified were: 1) 4-ethylphenol, 2) 2,3-dihydro-1- benzofuran, 3) 1- (2-methoxyphenyl) ethanol, 4) 2,6-dimethoxy-4- (prop-2-en-1-yl) phenol, 5) methyl (2E) -3- (4-hydroxyphenyl) prop-2-enoato.

Example 4: Depolymerization of lignin using the catalyst 5%

Ru / ZrO? / MWCNT (Sample C1)

In this experiment 50.6 mg of 5% Ru / ZrO2 / MWCNT were placed inside the reactor (23) together with 500.4 mg of lignin. Then, 30 ml of methanol was added to the reactor before closing the system and performing a leak test with N2. The reactor was purged three times with H2 to remove any remaining N2 and O2 present in the medium, and then pressurized at 25 bar with H2. The stirring speed was set to 750

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rpm and the temperature was raised from room temperature to 200 ° C in 120 min. Once the desired temperature was reached, the reaction began. After 4 h of reaction the heating and stirring were turned off and the reactor was cooled in an ice bath. When the reactor temperature was below 20 ° C, the reactor was carefully depressurized.

The analysis of the samples revealed the following results: the organics recovered in the flask accounted for 280.4 mg. The solids recovered were weighed, obtaining 235.2 mg, corresponding to solid lignin and the catalyst.

The closing of the balance of matter was 92.93%, with 56.04% corresponding to lignin converted into liquid products and 36.89% into solid products.

Figure 9 shows the GC-MS chromatogram obtained, in which the total area of the products obtained is 8.4 x 105 and the main products identified were: 1) ethyl 3- (4-hydroxy-3-methoxyphenyl) propanoate, 2) methyl-3- (4-hydroxyphenyl) acrylate, 3) 2,3-dihydro-1-benzofuran, 4) 4-ethylphenol and 5) methyl (2E) -3- (4-hydroxyphenyl) prop-2- enoate .

Figure 10 shows the results of HSQC obtained for the same lignin sample, after being treated in methanol for 4 h at 200 ° C, 750 rpm, and 25 bar of H2 in the presence of 5% Ru / ZrO2 / MWCNT catalyst nanoparticles . Various functional groups can be identified, as well as lignin monomers such as ferulate, p-coumarate, coumaril, guaiacil, siringil, p-O-P ’, p-O-4, p-O-5’, -CH3, and -OCH3. In addition, signals corresponding to oligosaccharides could be detected, which may be due to residual cellulose from the enzymatic hydrolysis and fermentation process. In this sample the p-O-4 bonds represented 8.1% of the total, which indicates that 80.7% of the bonds degraded after this treatment.

Example 5: Depolymerization of lignin using a 5% Ru / C catalyst

In this experiment, 50.4 mg of 5% Ru / C were placed inside the reactor (23) together with 500.1 mg of lignin. Then, 30 ml of methanol was added to the reactor before closing the system and performing a leak test with N2. The reactor was purged three times with H2 to remove any remaining N2 and O2 present in the medium, and then pressurized at 25 bar with H2. The stirring speed was set to 750

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rpm and the temperature was raised from room temperature to 200 ° C in 120 min. Once the desired temperature was reached, the reaction began. After 4 h of reaction the heating and stirring were turned off and the reactor was cooled in an ice bath. When the reactor temperature was below 20 ° C, the reactor was carefully depressurized

GC-MS analysis revealed the following results: the organics present in the flask were weighed, assuming 278.3 mg. The previously separated solids were also collected in a flask and dried in a rotary evaporator to remove any remaining solvent. The solids recovered were weighed, obtaining 278 mg, corresponding to solid lignin and the catalyst.

The closing of the balance of matter was 101.2%, with 55.6% of lignin converted to liquid products and 45.5% in solid products. The main products identified were: 1) 4-ethylphenol, 2) 2,3-dihydro-1-benzofuran, 3) 1- (2-

methoxyphenyl) ethanol, 4) 2,6-dimethoxy-4- (prop-2-en-1-yl) phenol, 5) methyl (2E) -3- (4- hydroxyphenyl) prop-2-enoate.

Main results

The reaction results are summarized in Table 3 where it can be identified that the percentage of mass of liquid produced using catalysts was increased compared to the blank (experiment without catalyst). It is possible to identify that when a catalyst is not used in the process the mass of organic liquids is significant (48%) when compared to the results observed when Ru / C and Ru / MWCNT are used as catalysts, in which the liquid fraction it represents 56% and 62%, respectively. It is important to consider that the fraction of liquids obtained after the reaction does not necessarily correlate with the degree of depolymerization since the liquid contains a mixture of oligomers that can be produced through the breaking of non-objective bonds such as -OH, O-CH3 , CC, and C = O, which lead to the formation of monomers. In contrast, 2D NMR can report the true degree of depolymerization since it is possible to determine the relative concentration of the target bonds (C-O of the p-O-4 type) in the lignin after reaction.

Table 3: Balance of matter, organic liquid and solid fractions obtained after the depolymerization reaction of vinasses (lignin current) of examples 15:

 Example

 Catalyst Recovered mass of organic liquid (%) Recovered mass of solids (%) Closing balance of matter (%)

 one

 Without catalyst 48 52 100

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 Sample A1: 5% Ru / ZrO2 Nanoparticles 62 52 114

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 Sample B1: 5% Ru / MWCNT 52

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 Sample C1: 5% Ru / ZrO2 / MWCNT 56 37 93

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 5% Ru / C 53 42 95

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The results obtained in the different 1H-13C inverse correlation spectra (HSQC) measured are shown in Table 4. The C-O bonds represent 60% of the total lignin bonds. Specifically, the p-O-4 bonds represent approximately 40% of the total C-O bonds in lignin, which have been considered as the target links. For this reason, the percentage of depolymerization of lignin was estimated using the relative change in the concentration of the p-O-4 bonds in the lignin (see Equation 1) after reaction.

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%

Depolymerization

[% P O 4] initial [% P O 4] f¿nai

[% P ~ 0—4] started

Ec. 1

The quantification of the pO-4 bonds in the lignin was based on the C2-H (G2) signals of the guaiacil (G) as an internal standard, since the C2 position of the guaiacil unit is never substituted, and is easily identifiable in the spectrum of HSQC (Ec. 2) and 20 where S is the area under the surface (HSQC).

% p-0- 4 = ^ reag- ° -4 * 100 Ec. 2

I Area p_0_4 + Area s2 + Area2G)

Table 4: Degree of depolymerization of p-O-4 obtained from the inverse correlation spectrum of 1H-13C (HSQC) measured in DMSO-d6 at 25 ° C for the lignin vinasses of the bioethanol production process, using methanol as solvent.

 Example

 Catalyst Reaction volume (ml)% P-O-4% depolymerization of p-O-4

 one

 Without catalyst 50 33.6% 19.8%

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 Sample A1: 5% Ru / ZrO2 50 23.4% 44.0%

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 Sample B1: 5% Ru / MWCNT 50 10.6% 74.7%

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 Sample C1: 5% Ru / ZrO2 / MWCNT 50 8.1% 80.7%

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 5% Ru / C 50 17.6% 57.9%

The catalytic activity towards depolymerization of the p-O-4 bonds of lignin varies significantly from one catalyst to another. For example, when the reaction is performed using the Ru / ZrO2 nanoparticle catalyst (Sample A1), the degree of depolymerization reached values of 44%. On the contrary, when the Ru / ZrO2 / MWCNT or Ru / MWCNT catalysts were used, the concentration of p-O-4 reduced by 80.7% and 74%, respectively. It is clear that making the catalyst more accessible to the bulk of the lignin polymer structure 15 by increasing the catalytic surface that interacts with the lignin is critical to maximize catalyst efficiency and therefore the degree of depolymerization of lignin.

However, when a high surface area material with high microporosity 20 (i.e. pore size less than 2 nm) such as activated carbon is used as a support

del Ru, the degree of depolymerization only reaches values between 57.9 and 70%,

depending on the volume of the reactor used. This indicates the strong dependence of the system on the accessibility of lignin to the active site. Lignin is a macromolecule that forms large agglomerates in solution (D = 0.1 pm - 2 pm) with a high diffusional radius, which makes it difficult to access the internal surface 5 of a material with a small pore size (2 nm - 50 nm) Therefore, when active carbon is used, lignin is not able to diffuse efficiently through the porous structure of the support to reach active sites. Instead, only small fragments (eg oligomers, dimers, and monomers) diffuse within the porous structure of active carbon, limiting their catalytic activity.

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Claims (50)

5 10 fifteen twenty 25 30 35 1. A process for the depolymerization of lignin, where the process comprises at least one stage a) of contact between a stream containing lignin with a catalyst consisting of a transition metal and a support, where the support is selected from the list consisting of • metal oxide nanoparticles • a one-dimensional structure • nanoparticles of metal oxides supported in a one-dimensional structure and said step (a) is carried out in the presence of • a reducing agent; Y • a solvent selected from the list consisting of water, ethanol, methanol, propanol, butanol, decalin, benzene, toluene, xylene, cyclohexane, gasoline, diesel and a combination thereof. 2. The process according to claim 1, wherein the transition metal is selected from the list consisting of Sn, Ga, Mg, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, La, Hf, Ta, W, Re, Os, Go, Pt, Au and combination thereof. 3. The process according to claim 2, wherein the transition metal is selected from the list consisting of Ni, Ru, Pd, Fe, Mo, Co, Cu, Fe and combination thereof. 4. The process according to claim 3, wherein the transition metal is selected from Ru, Ni and a combination thereof. 5. The process according to any one of claims 1 to 4, wherein the transition metal is in the form of a metal aggregate with a particle size between 1 and 100 nm. 6. The process according to claim 5, wherein the transition metal is in the form of a metal aggregate with a particle size between 2 and 50 nm. 10 fifteen twenty 25 7. The process according to claim 6, wherein the transition metal is in the form of a metal aggregate with a particle size between 2 and 5 nm. 8. The process according to any one of claims 1 to 7, wherein the metal oxide nanoparticles are selected from the list consisting of SiO2, TiO2, V2O5, Cr2O3, MnO2, MgO, Fe2O3, FeO, CoO, ZnO, Y2O3, ZrO2 , Nb2O5, CdO, La2O3, SnO2, HfO2, Ta2O5, WO3, Re2O7, Al2O3, CeO2, Cs2O and combination thereof. 9. The process according to claim 8, wherein the metal oxide nanoparticles is selected from the list consisting of TiO2, V2O5, Cr2O3, MnO2, ZrO2, CeO2 and combination thereof. 10. The process according to claim 9, wherein the metal oxide nanoparticles are selected from the list consisting of TiO2, V2O5, MnO2, ZrO2, CeO2 and combination thereof. 11. The process according to any one of claims 1 to 10, wherein the one-dimensional structure is selected from the list consisting of C nanotubes, TiO2 nanotubes, V2O5 nanotubes, MnO2 nanotubes, ZrO2 nanotubes, carbon fibers, sheets of graphene and combination thereof. 12. The process according to claim 11, wherein the one-dimensional structure is nanotubes of C. 13. The process according to claim 12, wherein the nanotubes of C have a length: diameter aspect ratio that varies between 5 and 2000 with lengths between 50 nm and 5000 nm. 14. The process according to any of claims 11 to 13, wherein the one-dimensional structure comprises magnetic nanoparticles on its surface. 15. The process according to claim 14, wherein the magnetic nanoparticles are Fe (III) oxide nanoparticles. 16. The process according to claim 15, wherein the weight percentage of the Fe (III) metal oxides nanoparticles in the one-dimensional structure vary between 5% and 60% by weight. The process according to claim 16, wherein the percentage by weight of the Fe (III) metal oxide nanoparticles in the one-dimensional structure vary between 10% and 50% by weight. 18. The process according to claim 17, wherein the weight percentage of the 10 nanoparticles of Fe (III) metal oxides in the one-dimensional structure vary between 20% and 40% by weight. 19. The process according to any of claims 1 to 18, wherein the agent reducer is selected from the list consisting of hydrogen, formic acid, ethanol, 15 methanol and combination thereof. 20. The process according to any of claims 1 to 19, wherein step a) is carried out at pressures between 10 bar and 100 bar and temperatures between 150 ° C and 400 ° C. twenty 21. The process according to claim 20, wherein step a) is carried out at pressures between 10 bar and 70 bar. 22. The process according to claim 21, wherein step a) is carried out at pressures 25 between 30 bar and 60 bar. 23. The process according to claim 22, wherein step a) is carried out at pressures between 40 bar and 60 bar. 24. The process according to any of claims 20 to 23, wherein step a) is performed at temperatures between 150 ° C and 300 ° C. 25. The process according to claim 24, wherein step a) is carried out at temperatures between 150 ° C and 250 ° C. 26. The process according to claim 25, wherein step a) is carried out at temperatures between 180 ° C and 200 ° C. 27. The process according to any one of claims 1 to 26, wherein the current which 5 contains lignin used in step a) has been previously purified. 28. The process according to any one of claims 1 to 27, wherein the pH of the current containing lignia of step a) is between 4 and 8. The process according to claim 28, wherein the pH of the stream it contains lignin from stage a) is between 4 and 6. 30. The process according to any one of claims 1 to 29, comprising a step b) of catalyst recovery. fifteen 31. The process according to claim 30, wherein step b) of catalyst recovery is carried out by filtration. 32. The process according to any of claims 30 or 31, which comprises a 20 stage b ’) of catalyst recovery through the application of a field magnetic between 0.1 Teslas and 5 Teslas, where said catalyst comprises a one-dimensional structure comprising magnetic nanoparticles on its surface. The process according to any one of claims 1 to 32, which comprises a step c) of purification of the stream obtained in stages b) or b ’) by separating a stream consisting of a solvent and a stream containing non-depolymerized lignin from another stream consisting of aromatic compounds derived from lignin. 30 34. A process for obtaining ethanol and / or butanol comprising • steps a) to c) of depolymerization of lignin according to any of claims 1 to 33; Y • a stage d) of contact between genetically microorganisms 35 modified with the aromatic compounds derived from lignin in the stage c). 10 fifteen twenty 25 30 35. The process according to claim 34, wherein the genetically modified microorganisms is selected from the list consisting of basidiomycetes fungi, chrysosporium phanerochaete, and streptomyces spp. 36. A catalyst comprising a transition metal and a support, where the support consists of nanoparticles of metal oxides supported in a one-dimensional structure. 37. The catalyst according to claim 36, wherein the transition metal is selected from the list consisting of Sn, Ga, Mg, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, La, Hf, Ta, W, Re, Os, Go, Pt, Au and combination thereof. 38. The catalyst according to claim 37, wherein the transition metal is selected from the list consisting of Ni, Ru, Pd, Fe, Mo, Co, Cu, Fe and combination thereof. 39. The catalyst according to claim 38, wherein the transition metal is selected from Ru, Ni and combinations thereof. 40. The catalyst according to any of claims 36 to 39, wherein the transition metal is in the form of a metal aggregate with particle sizes between 1 nm and 100 nm. 41. The catalyst according to claim 40, wherein the transition metal is in the form of a metal aggregate with particle sizes between 2 nm and 50 nm. 42. The catalyst according to claim 41, wherein the transition metal is in the form of a metal aggregate with particle sizes between 2 and 5 nm. 43. The catalyst according to any of claims 36 to 42, wherein the metal oxide nanoparticles are selected from the list consisting of SiO2, TiO2, V2O5, C2O3, MnO2, MgO, Fe2O3, FeO, CoO, ZnO, Y2O3, ZrO2 , Nb2O5, CdO, 10 fifteen twenty 25 30 La2Ü3, SnO2, HfO2, Ta2Ü5, WO3, Re2O7, AI2O3, CeO2, CS2O and combination thereof. 44. The catalyst according to claim 43, wherein the metal oxide nanoparticles are selected from the list consisting of TiO2, V2O5, Cr2O3, MnO2, ZrO2, CeO2 and combination thereof. 45. The catalyst according to claim 44, wherein the metal oxide nanoparticles are selected from the list consisting of TiO2, V2O5, MnO2, ZrO2, CeO2 and combination thereof. 46. The catalyst according to any of claims 36 to 45, wherein the one-dimensional structure selected from the list consisting of C nanotubes, TiO2 nanotubes, V2O5 nanotubes, MnO2 nanotubes, ZrO2 nanotubes, carbon fibers, sheets of graphene, and combination thereof. 47. The catalyst according to claim 46, wherein the one-dimensional structure are nanotubes of C. 48. The catalyst according to claim 47, wherein the C nanotubes have a length: diameter aspect ratio that varies between 5 and 2000 with lengths between 50 nm and 5000 nm. 49. The catalyst according to claim 48, wherein the one-dimensional structure comprises magnetic nanoparticles on its surface. 50. The catalyst according to claim 49, wherein the magnetic nanoparticles are magnetic nanoparticles of Fe (III) oxide. 51. The catalyst according to claim 50, wherein the percentage by weight of the magnetic nanoparticles of Fe (III) in the one-dimensional structure varies between 5% and 60% by weight. 52. The catalyst according to claim 51, wherein the percentage by weight of the magnetic nanoparticles of Fe (III) oxides in the one-dimensional structure varies between 10% and 50% by weight. 53. The catalyst according to claim 52 wherein the percentage by weight of the magnetic nanoparticles of Fe (III) oxides in the one-dimensional structure varies between 20% and 40% by weight 5 54. Use of the catalyst described in any of claims 36 and 53 for depolymerization of lignin. 10