METHOD FOR SYNTHESISING A LIQUID ORGANIC HYDROGEN CARRIER (LOHC) LOADED WITH HYDROGEN USING HYDROGEN PRODUCED FROM A METHANISATION DIGESTATE

Abstract

A synthesis process of a liquid organic hydrogen carrier charged with hydrogen, Hn-LOHC, wherein a methanisation digestate is used as a hydrogen source, including at least the steps of: a) production of gaseous ammonia from the methanisation digestate; b) division of the gaseous ammonia produced in step a) into a first and a second flow; c) catalytic amination of a liquid organic hydrogen carrier not charged with hydrogen, H0-LOHC, by reaction with the gaseous ammonia from the first flow to convert the H0-LOHC into an aminated H0-LOHC and produce hydrogen; d) catalytic dissociation of gaseous ammonia from the second flow to produce hydrogen; and e) catalytic hydrogenation of the aminated H0-LOHC obtained in step c), by reacting with the hydrogen produced in steps c) and d), whereby the Hn-LOHC is obtained.

Claims

1. A synthesis process of a liquid organic hydrogen carrier charged with hydrogen, H.sub.n-LOHC, comprising at least the steps of: a) production of gaseous ammonia from a methanisation digestate; b) division of the gaseous ammonia produced in step a) into a first and a second flow; c) catalytic amination of a liquid organic hydrogen carrier not charged with hydrogen, H.sub.0-LOHC, by reaction with the gaseous ammonia from the first flow to convert the H.sub.0-LOHC into an aminated H.sub.0-LOHC and produce hydrogen; d) catalytic dissociation of the gaseous ammonia from the second flow to produce hydrogen; and e) catalytic hydrogenation of the aminated H.sub.0-LOHC obtained in step c), by reaction with the hydrogen produced in steps c) and d), whereby the H.sub.n-LOHC is obtained.

2. The process of claim 1, wherein the methanisation digestate is a liquid digestate comprising ammoniacal nitrogen.

3. The process of claim 2, wherein the production of gaseous ammonia comprises a desorption of the ammoniacal nitrogen of the liquid digestate in the form of gaseous ammonia.

4. The process of claim 3, wherein the desorption comprises a circulation of the liquid digestate in a packing column, against a flow of nitrogen or a gas essentially consisting of nitrogen.

5. The process of claim 1, further comprising a purification of the gaseous ammonia produced.

6. The process of claim 1, wherein the catalytic dissociation of the gaseous ammonia is carried out in a reactor heated to a temperature between 450? C. and 800? C.

7. The process of claim 1, further comprising a purification of the hydrogen produced by the catalytic dissociation of gaseous ammonia.

8. The process of claim 1, wherein the H.sub.0-LOHC is an aromatic or heteroaromatic, monocyclic or polycyclic, compound, optionally substituted by one or more alkyl, aryl, heteroaryl, arylalkyl or heteroarylalkyl groups.

9. The process of claim 8, wherein the H.sub.0-LOHC is toluene, 2-benzyltoluene, 4-benzyltoluene, 2,3-dibenzyltoluene, 2,4-dibenzyltoluene, naphthalene, N-ethylcarbazole, indole, 1-methylindole, 2-methylindole, 3-methylindole, 4-methylindole, 5-methylindole, 6-methylindole, 1,2-dimethylindole, 2,3-dimethylindole, 2,5-dimethylindole, dibenzofuran, phenazine, 2-(N-methylbenzyl)pyridine or 4,4-bipiperidine.

10. The process of claim 1, wherein the catalytic amination of the H.sub.0-LOHC is carried out in a reactor heated at a temperature between 200? C. and 800? C. and at a pressure between 0.1 MPa and 90 MPa.

11. The process of claim 1, further comprising a purification of the hydrogen produced by the catalytic amination of the H.sub.0-LOHC.

12. The process of claim 1, wherein the catalytic hydrogenation of the aminated H.sub.0-LOHC is carried out with a hydrogen pressure between 5 MPa and 10 MPa.

13. The process of claim 6, wherein the reactor is heated by heat or electricity produced from a methanisation biogas.

14. A process for recycling organic waste, comprising at least the steps of: methanisation of the organic waste to produce a methanisation digestate and a biogas; synthesis of a liquid organic hydrogen carrier charged with hydrogen, H.sub.n-LOHC, from the methanisation digestate by implementing the process of claim 1; and production of heat or electricity from the biogas.

15. A process for producing hydrogen, comprising at least the steps of: synthesis of a liquid organic hydrogen carrier charged with hydrogen, H.sub.n-LOHC, by implementing the process of claim 1; packaging the H.sub.n-LOHC for storage and/or transport; and catalytic dehydrogenation of the H.sub.n-LOHC thus packaged.

16. The process of claim 10, wherein the reactor is heated by heat or electricity produced from a methanisation biogas.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0081] FIG. 1 schematically illustrates a preferred mode of implementation of the synthesis process of an H.sub.n-LOHC according to the invention and embodiment of an installation designed for this mode of implementation.

[0082] FIG. 2 schematically illustrates a preferred mode of implementation of the process for recycling organic waste according to the invention and embodiment of an installation designed for this mode of implementation.

DETAILED DISCLOSURE OF A PARTICULAR MODE OF IMPLEMENTATION

[0083] Reference is made to FIG. 1 which schematically represents a preferred mode of implementation of the synthesis process of an H.sub.n-LOHC according to the invention and embodiment of an installation, referenced 10, designed for this mode of implementation.

[0084] In this mode of implementation, the process comprises:

[0085] 1. production of gaseous ammonia, NH.sub.3, by desorption (or stripping) of ammoniacal nitrogen from a liquid digestate;

[0086] 2. purification of the gaseous ammonia thus produced and splitting thereof into a first and a second flow;

[0087] 3. catalytic amination of an H.sub.0-LOHC by means of the gaseous ammonia from the first flow to convert this H.sub.0-LOHC into an aminated H.sub.0-LOHC and produce hydrogen;

[0088] 4. catalytic dissociation of gaseous ammonia from the second flow to produce hydrogen;

[0089] 5. purification of the hydrogen produced by the catalytic amination of the H.sub.0-LOHC and by the catalytic dissociation of ammonia; and

[0090] 6. catalytic hydrogenation of the aminated H.sub.0-LOHC by means of the hydrogen thus purified to convert this aminated H.sub.0-LOHC into an aminated H.sub.n-LOHC.

[0091] For this purpose and as seen in FIG. 1, the installation 10 comprises a desorption column 11, which is filled with a packing 12 such as Raschig or Pall rings and wherein the production of gaseous ammonia is carried out.

[0092] The liquid digestate, which is subjected to this desorption, is obtained from the separation into a solid phase and a liquid phase of a methanisation digestate.

[0093] This liquid digestate essentially comprises nitrogen of which ammoniacal nitrogen, phosphorus in oxide form (P.sub.2O.sub.5), potassium in oxide form (K.sub.2O), calcium in oxide form (CaO) and magnesium, also in oxide form (MgO), in variable concentrations according to the organic waste from which the methanisation digestate was obtained.

[0094] The column 11 is supplied: [0095] at the top, with the liquid digestate via a pump (not shown in FIG. 1), and [0096] at the base, with a transfer gas which can be nitrogen or a gas essentially consisting of nitrogen such as air but which, in the case of the mode of implementation of the process illustrated in FIG. 1, is nitrogen, which is injected under pressure in the column 11 from a nitrogen source 13.

[0097] The liquid digestate and the nitrogen therefore circulate countercurrently in the column 11.

[0098] The nitrogen can be heated prior to its entry into the column 11, for example at a temperature of 50? C. to 70? C., to promote the desorption of the ammoniacal nitrogen.

[0099] At the top of the column 11, a gas phase is recovered essentially formed of ammonia and nitrogen and, at the base of the column 11, an ammoniacal nitrogen-depleted liquid digestate.

[0100] The gas phase thus recovered is directed towards a purification device 14, for example of the membrane filter type, making it possible to purify the ammonia by separating it from nitrogen and any other gases generated by the desorption, whereas the ammoniacal nitrogen-depleted digestate is removed from the process while being, for example, directed towards a storage unit (not shown in FIG. 1) with a view to subsequent spreading.

[0101] As seen in FIG. 1, the nitrogen coming out of the purification device 14 can, after itself undergoing an optional purification, be directed towards the nitrogen source 13 with a view to its reinjection into the column 11. Alternatively, it can also be removed from the process for its reuse in other applications or, more simply, its release into the atmosphere.

[0102] As regards the ammonia coming out of the purification device 14, it is split into two flows: a first flow which is directed towards a reactor 15 intended for the catalytic amination of the H.sub.0-LOHC and which is, therefore, supplied with this H.sub.0-LOHC, and a second flow which is directed towards a reactor 16 intended for the catalytic dissociation of ammonia.

[0103] In the reactor 15, the catalytic amination of the H.sub.0-LOHC is, for example, carried out at a temperature between 350? C. and 500? C. and at a pressure between 1.5 MPa and 11 MPa, using an Ni/CeO.sub.2 type catalyst.

[0104] As mentioned above, the yield from the animation of the H.sub.0-LOHC can be increased by consuming a portion of the hydrogen generated by this amination, by supplying the reactor 15 with a oxidising gas such as oxygen, carbon monoxide, carbon dioxide, nitrogen monoxide, nitrogen dioxide, hydrogen peroxide or air. In which case, the portion of the hydrogen generated by the catalytic amination of the H.sub.0-LOHC which is not consumed in the reactor 15 is evacuated from this reactor through, for example, a membrane filter to separate it from the oxidising gas.

[0105] Whether an oxidising gas is used or not for the catalytic amination of the H.sub.0-LOHC, the hydrogen coming out of the reactor 15 is then directed towards a purification device 18, for example of the membrane filter type, whereas the aminated H.sub.0-LOHC is directed towards a reactor 17 intended for its hydrogenation.

[0106] In parallel, in the reactor 16, the catalytic dissociation of the gaseous ammonia from the second flow from the purification device 14 is carried out. This dissociation is, for example, performed at a temperature between 550? C. and 700? C. and using an Ni/MgO catalyst.

[0107] The hydrogen produced in the reactor 16 is then directed towards the purification device 18 where it joins the hydrogen evacuated from the reactor 15.

[0108] Once purified by the purification device 18, the hydrogen is directed towards the reactor 17 to be used for the catalytic hydrogenation of the aminated H.sub.0-LOHC.

[0109] This hydrogenation is, for example, carried out with a hydrogen pressure between 5 MPa and 10 MPa and using a Ru/Al.sub.2O.sub.3 type catalyst.

[0110] The aminated H.sub.n-LOHC produced in the reactor 17 is then sent to a zone intended for its packaging (not shown in FIG. 1) for storage and/or transport.

[0111] Reference is made to FIG. 2 which schematically represents a preferred mode of implementation of the process for recycling organic waste according to the invention and an installation, referenced 20, designed for this mode of implementation.

[0112] In this mode of implementation, the process for recycling organic waste comprises:

[0113] 1. methanisation of the organic waste to produce a methanisation digestate, on one hand, and a biogas, on the other;

[0114] 2. separation of the methanisation digestate into a solid phase, referred to as solid digestate, and a liquid phase, referred to as liquid digestate;

[0115] 3. synthesis of an H.sub.n-LOHC from the liquid digestate by the synthesis process of an H.sub.n-LOHC according to the invention; and

[0116] 4. cogeneration, i.e. simultaneous production of electricity and heat, from the biogas.

[0117] For this purpose and as seen in FIG. 2, the organic waste, which can in particular be agricultural waste such as cattle manure, pig manure or cereal residue, urban waste such as household waste or wastewater treatment plant sludge, industrial waste such as agri-food industry waste, or a mixture of waste from different sources, are introduced into the methaniser, also known as digester, of a methanisation unit 21, wherein they are subjected to an anaerobic fermentation, typically at a temperature between 20? C. and 60? C., which results in the formation, on one hand, of a pasty product called methanisation digestate and, on the other, a biogas which essentially consists of CH.sub.4 and CO.sub.2.

[0118] The methanisation digestate, once evacuated from the methaniser 21, is directed towards a solid/liquid separation unit 22 wherein it is separated into a solid digestate and a liquid digestate, for example by means of one or more screw press, belt press, filter press or centrifuge type devices.

[0119] The solid digestate thus obtained can be sent to a storage unit (not shown in FIG. 2) with a view to subsequent spreading and/or to a post-treatment unit (not shown in FIG. 2) of the drying or composting unit type.

[0120] As regards the liquid digestate, it is directed towards an installation 23 intended for the synthesis of the H.sub.n-LOHC, which can in particular be an installation of the type of that shown in FIG. 1. The H.sub.n-LOHC thus synthesised is then directed towards a zone intended for its packaging (not shown in FIG. 2) for storage and/or transport.

[0121] In parallel, the biogas produced in the methaniser 21 is directed towards a cogeneration unit 24 comprising, for example, a gas turbine coupled with an alternator and a heat recovery unit.

[0122] As illustrated in FIG. 2, the electricity and/or heat thus produced can in particular be used for operating: [0123] the methanisation unit 21 and, in particular, for heating the methaniser, [0124] the solid/liquid separation unit 22, and/or [0125] the installation 23 intended for the synthesis of the H.sub.n-LOHC and, in particular, for heating the transfer gas used for the desorption of ammoniacal nitrogen if the gaseous ammonia is produced by desorption and for heating the reactors wherein the catalytic dissociation of the gaseous ammonia and, where applicable, the catalytic amination of the H.sub.0-LOHC are carried out.

[0126] Optimal recycling of organic waste is thus carried out.

CITATION

[0127] Purna Chandra Rao and Minyoung Yoon, Energies 2020, 13(22), 1-23