Functionalized nanodiamonds and catalysts thereof for high-flow rate catalytic of h 2 delivery from solid storage

Abstract

The present invention relates to metallic nanoparticles stabilized by a diamondoid ligand. Nanoparticles, and networks of nanoparticles, of controlled small sizes below 10 nm, are used and recycled for the efficient delivering, in high rate, of hydrogen gas H2, extracted from solid organic sources in hydrolysis and solvolysis reactions.

Description

[0001]Functionalized nanodiamonds and catalysts thereof for high-flow rate catalytic ofH2 delivery from solid storage Technical field The present invention relates to nanoparticles stabilized with diamondoidligands, and networks of these nanoparticles, and their use for the delivery ofhydrogen (H2) from chemical solid storage using borohydrides or borane compounds.Background art France aims for carbon neutrality in 2050 (Law N°2019-1147 of 8 November 2019 relative to energy and climate). Among the objectives set by government, thereis a focus on development of H2 solution as decarbonated clean energy vector for thefuture energy mix (both at a storage and transport solution).The existing solutions for H2 storage are gaseous and / or liquid. However,these solutions require huge volume of storage and there are risks of accident linkedto H2, such as fire or explosion. Specific regulations relating to H2 storage andconception and exploitation of H2 distribution resorts have thus been created. Thereis thus a need to develop safer and economical routes for H2 storage, notably in linkwith transportation and mobility applications but also concerning societal acceptability. The chemical storage of H2under solid form represents a secure and cleanenergy vector. It is for example known the solid storage of H2 under the form of light-mass solids, highly hydrogenated, able to release H2 upon thermolysis or solvolysis,in the presence of a catalyst or not, such as borane derivatives. However, there is aneed to provide methods for controlled and secured delivery of H2 via solid route.There is also a need to provide such method than can be more environmentallyfriendly and cost effective by using low traces of metal and / or and that enables todeliver very high-flow rate of H2 in reduced time. The development of specific, easily recoverable and recyclable, catalysts that can provide very high rates of extraction of H2 from storable as secured solid sources, is a key issue in this perspective. Summary of the invention The present invention relates to metallic nanoparticles stabilized bydiamondoid ligands, wherein each diamondoid molecule is substituted by at leastone group, identical or different, selected in the group consisting of PR2; wherein R, identical or different, represents H; a C5-C10aryl group, preferably phenyl,a C5-C10 cycloalkyl group, preferably cyclohexyl; or a C1-C30 alkyl, preferably C1-C10alkyl, more preferably C1-C5alkyl, linear or branched, saturated or partially or totally unsaturated; preferably R is H;wherein the metal of the nanoparticle is selected in the group consisting of Fe, Ni,Co, Cr, V, Rh, Ru, Os, Re, preferably Ni or Ru; andwherein the atomic ratio of the metal of the nanoparticle to the ligand of thenanoparticle is equal or greater than 5 / 1, preferably comprised between 5 / 1 and20 / 1, preferably comprised between 8 / 1 and 15 / 1. Preferably, the metal of the nanoparticle is ruthenium, nickel, platinum, rhodium or cobalt, preferably ruthenium or nickel, preferably ruthenium. According to one embodiment, the diamondoid ligand is chosen among compound having the formula : -[CnHn+6-m](PR2)m, wherein:^ n is 10, 14, 18, 22, 26 or 30^ m is from 1 to 10, preferably from 1 to 6, more preferably from 1 to 4,even more preferably m is 2^ R, identical or different, represents H; a C5-C10 aryl group, preferablyphenyl, a C5-C10 cycloalkyl group, or a C1-C30 preferably C1-C10 alkyl,more preferably C1-C5 alkyl, linear or branched, saturated or partially ortotally unsaturated; preferably R is H.- [C10qH16q-r-s](PR2)s, wherein:^ q is 2 or 3^ r is 2 when q is 2, r is 4 when q is 3^ s is from 1 to 10, preferably from 1 to 6, more preferably from 1 to 4; evenmore preferably s is 2^ R, identical or different, represents H; a C5-C10 aryl group, preferablyphenyl, a C5-C10 cycloalkyl group, preferably; or a C1-C30 preferably C1-C10 alkyl, more preferably C1-C5alkyl, linear or branched, saturated or partially or totally unsaturated; preferably R is H.According to one embodiment, the diamondoid ligand is chosen amongcompounds having the following formula (I) or (II): wherein m is from 1 to 6 in formula (I), preferably from 1 to 4, more preferablym is 2, and m is from 1 to 8 in formula (II), preferably from 1 to 6, more preferablyfrom 1 to 4, even more preferably m is 2wherein R, identical or different, represents H; a C5-C10 aryl group, preferably phenyl, a C5-C10 cycloalkyl group, preferably cyclohexyl; or a C1-C30 preferably C1-C10 alkyl, more preferably C1-C5 alkyl, linear or branched, saturated or partially or totallyunsaturated; preferably R is H.In the above embodiments, R is preferably H. The invention also relates to the use of a metallic nanoparticle stabilized by diamondoid ligands, wherein each diamondoid molecule is substituted by at least one group, identical or different, selected in the group consisting of COOR, PR2, SR or NR2;wherein R, identical or different, represents H; a C5-C10 aryl group, preferably phenyl, a C5-C10 cycloalkyl group, preferably cyclohexyl; or a C1-C30 preferably C1-C10 alkyl, more preferably C1-C5 alkyl, linear or branched, saturated or partially or totally unsaturated; preferably R is H;wherein the metal of the nanoparticle is selected in the group consisting of Fe, Ni, Co, Cr, V, Rh, Ru, Os, Re, preferably Ni or Ru; and wherein the atomic ratio of the metal of the nanoparticle to the ligand of the nanoparticle is equal or greater than 5 / 1, preferably comprised between 5 / 1 and 20 / 1, preferably comprised between 8 / 1 and 15 / 1, as catalyst for the recovery of H2 by hydrolysis or solvolysis of borohydrides or borane compounds, wherein the solvent is preferentially a polar hydrogen donor, more preferentially an alcohol or water. The present invention also relates to a process for recovering H2from borohydrides or borane compounds by hydrolysis or solvolysis in the presence of ametallic nanoparticle as disclosed above.In one embodiment, the diamondoid ligand is chosen among compound having the formula :- [CnHn+6-m](Z)m, wherein:^ Z is selected in the group of COOR, PR2, SR or NR2^ n is 10, 14, 18, 22, 26 or 30^ m is from 1 to 10, preferably from 1 to 6, more preferably from 1 to 4,even more preferably m is 2 ^R, identical or different, represents H; a C5-C10 aryl group, preferablyphenyl, a C5-C10 cycloalkyl group, preferably cyclohexyl; or a C1-C30 preferably C1-C10 alkyl, more preferably C1-C5 alkyl, linear or branched, saturated or partially or totally unsaturated; preferably R is H,- [C10qH16q-r-s](Z)s, wherein:^ Z is selected in the group of COOR, PR2, SR or NR2^ q is 2 or 3^ r is 2 when q is 2, r is 4 when q is 3^ s is from 1 to 10, preferably from 1 to 6, more preferably from 1 to 4; evenmore preferably s is 2 ^R, identical or different, represents H; a C5-C10 aryl group, preferablyphenyl, a C5-C10 cycloalkyl group, preferably; or a C1-C30 preferably C1-C10 alkyl, more preferably C1-C5 alkyl, linear or branched, saturated or partially or totally unsaturated; preferably R is H.In one embodiment, the diamondoid ligand is chosen among compoundshaving the following formula (VIII) or (IX): (VIII) (IX) Wherein:^ Z is selected in the group of -COOR, -PR2, SR or -NR2, preferably -COOR, -PR2, or -NR2, more preferably -COOR, -PR2;^ wherein m is from 1 to 6 in formula (VIII), preferably from 1 to 4, more preferablym is 2, and m is from 1 to 8 in formula (IX), preferably from 1 to 6, morepreferably from 1 to 4, even more preferably m is 2^ R, identical or different, represents H; a C5-C10 aryl group, preferably phenyl, aC5-C10cycloalkyl group, preferably cyclohexyl; or a C1-C30preferably C1-C10alkyl, more preferably C1-C5 alkyl, linear or branched, saturated or partially or totallyunsaturated; preferably R is H. In one embodiment, borohydrides are sodium borohydride (NaBH4) orlithium borohydride (LiBH4). In one embodiment, borane compounds are amine-borane or analogous amine-borane, hydrazine-borane. Preferably, the analogous amine-borane is of formula NR2'H-BH3 or BH3-NR2'-(CH2)m- NR2'-BH3, wherein R' identical or different, represent H, a C5-C10 aryl group,preferably a phenyl group; or a C1-C30, preferably C1-C10 alkyl, more preferably C1-C5alkyl group, linear or branched, saturated or unsaturated, m is 1, 2 or 3, preferably,the amine-borane is NH3-BH3 (AB), NMeH2-BH3 (methylamineborane MeAB), NMe2H-BH3 (dimethyl amine-borane DMAB) or H3B-NH2CH2CH2H2N-BH3 (ethylene diamine bisborane EDAB). In one embodiment, the solvolysis is carried out using ethanol. Preferably, the reaction is carried out at a temperature comprised between - 90 °C and 100 °C, preferably between -40 °C and 80 °C, more preferentially between 0 °C and 30 °C, more preferentially 20 °C. Preferably, the reaction is carried out so that the molar ratio of metal fromthe nanoparticle to the borane compound is comprised between 0.0001 and 0.1,preferably between 0.001 and 0.05, more preferentially between 0.01 and 0.025. In one embodiment, the process according to the invention further comprisesa step of recycling the nanoparticles, preferably carried out by recovering the nanoparticles and washing the recovered nanoparticles with the solvent used for the hydrolysis or solvolysis of the borane compound. Brief description of the Figure The diamondoid ligands present the advantage to have a highly regular andrigid structure with chemical functional groups. This enables to stabilize the surfaceof the individual nanoparticles by strong bonds, but also the advantage to link thenanoparticles together in dense networks. The formation of a network during nanoparticles growth advantageously enables to control the size of the nanoparticles,preferably between 1 and 3 nm with a narrow particle size distribution. Narrowparticle size distribution is characterized by a standard deviation of the particle sizeof at most 1 nm. Interparticle distance corresponds to nanoparticles surface tosurface distance. Such small size and high density of metallic nanoparticlesadvantageously lead to high activity because of large exposed metal surface. Thisapproach to stabilize nanoparticles, without external supplementary support of theoxide or carbon also makes it possible to overcome the possible instability of isolated nanoparticles. Figure 1 represents a fragment of three nanoparticles stabilized withdiamondoid ligand according to the invention and forming a network.Detailed description The invention is now described in more detail and in a non-limiting manner in the following description. The following terms and expressions contained herein are defined as follows. As used herein, the term "diamondoid" (alternatively named “ nanodiamond”, ND) refers to hydrocarbons containing at least one adamantane unitor largely superimposable on the diamond lattice. Typically, one or more adamantaneunits are present, the diamondoid can be classified according to their number ofcarbon atoms. All other terms used in the description of the present invention have their meanings as is well-known in the art. The present invention relates to metallic nanoparticle stabilized bydiamondoid ligands, wherein each diamondoid molecule is substituted by at leastone group, identical or different, selected in the group consisting of PR2; wherein R, identical or different, represents H; a C5-C10 aryl group, preferably phenyl, a C5-C10 cycloalkyl group, preferably cyclohexyl; or a C1-C30 preferably C1-C10 alkyl,more preferably C1-C5 alkyl, linear or branched, saturated or partially or totally orunsaturated; preferably R is H;wherein the metal of the nanoparticle is selected in the group consisting of Fe, Ni,Co, Cr, V, Rh, Ru, Os, Re, preferably Ni or Ru; andwherein the atomic ratio of the metal of the nanoparticle to the ligand of thenanoparticle is equal or greater than 5 / 1, preferably comprised between 5 / 1 and20 / 1, preferably comprised between 8 / 1 and 15 / 1. Preferably, the metallic nanoparticles have a mean diameter, as measured from transmission electronic microscopy in the solid state or diffusion light scatteringin liquid dispersion, comprised between 0.5 and 50 nm, preferably between 0.5 and10 nm, more preferably between 0.5 and 2 nm. Preferably, the diamondoid ligand is chosen among compound of formula :- [CnHn+6-m](PR2)m, wherein:^ n is 10, 14, 18, 22, 26 or 30^ m is from 1 to 10, preferably from 1 to 6, more preferably from 1 to 4;even more preferably m is 2^ R, identical or different, represents H; a C5-C10 aryl group, preferablyphenyl, a C5-C10 cycloalkyl group, preferably cyclohexyl ; or a C1-C30 preferably C1-C10 alkyl, more preferably C1-C5 alkyl, linear or branched, saturated or partially or totally or unsaturated; preferably R is H ;- [C10qH16q-r-s](PR2)s, wherein:^ q is 2 or 3^ r is 2 when q is 2, r is 4 when q is 3^ s is from 1 to 10, preferably from 1 to 6, more preferably from 1 to 4; evenmore preferably s is 2 ^R, identical or different, represents H; a C5-C10 aryl group, preferablyphenyl, a C5-C10cycloalkyl group, preferably; or a C1-C30preferably C1-C10alkyl, more preferably C1-C5alkyl, linear or branched, saturated or partially or totally unsaturated; preferably R is H.The diamondoid ligand is chosen among compound having the followingformula (I), (II), (III), (IV) or (V) wherein m is from 1 to 6 in formula (I), preferably from 1 to 4, more preferably m is2; m is from 1 to 8 in formula (II), preferably from 1 to 6, more preferably from 1 to4, even more preferably m is 2, m is from 1 to 10 in formula (III) to (V), preferablyfrom 1 to 6, more preferably from 1 to 4; even more preferably m is 2;wherein in formula (VI) and (VII) 1 to 10 hydrogen atoms, preferably 1 to 6, morepreferably from 1 to 4, even more preferably 2 hydrogen atoms, is substituted by PR2;wherein R, identical or different, represents H; a C5-C10 aryl group, preferably phenyl, a C5-C10 cycloalkyl group, preferably cyclohexyl; or a C1-C30 preferably C1-C10 alkyl, more preferably C1-C5 alkyl, linear or branched, saturated or partially or totally unsaturated; preferably R is H. Preferably, the diamondoid ligand is of formula (I), (II) or (VI). Preferably, the diamondoid ligand is of formula (I), (II) or (VI) and PR2 is PH2.Preferably, the diamondoid ligand is of formula (I), (II) or (VI) and m is 2. Preferably, the diamondoid ligand is of formula (I), (II) or (VI), m is 2 and PR2is PH2. Preferably, the diamondoid ligand is of formula (I) or (II). Preferably, the diamondoid ligand is of formula (I) or (II) and PR2is PH2. Preferably, the diamondoid ligand is of formula (I) or (II) and m is 2. Preferably, the diamondoid ligand is of formula (I) or (II), m is 2 and PR2is PH2. Preferably, the diamondoid ligand is of formula (I) or (II) and comprises twogroups PR2, preferably PH2, in positions 1 and 3 in formula (I) and positions 4 et 9 informula (II). Positions of PR2 formula (I) and (II) are illustrated below. Preferably, R of diamondoid ligand of the metallic nanoparticle is H. The diamondoid ligand according to the present invention can be synthetized by method known by the skilled person and especially following the process disclosedin: Min Y., Nasrallah H., Poinsot D., Lecante P., Tison Y., Martinez H., Roblin P., FalquiA., Poteau R., Rosal I., Gerber I. C., Hierso J-C., Axet M. R., Serp P. 3D rutheniumnanoparticle covalent assemblies from polymantane ligands for confined catalysis.Chemistry of Materials 2020, 32, 2365-2378; Moncea O., Gunawan M. A., Poinsot D.,Cattey H., Becker J., Yurchenko R. I., Butova E. D., Hausmann H., Sekutor M., Fokin A.A., Hierso J-C., Schreiner P. R. The Journal of Organic Chemistry.2016, 81, 8759-8769. When each diamondoid ligand is substituted by at least one group, identicalor different, of formula PR2 such as defined above with R is H; a C5-C10 aryl group,preferably phenyl, a C5-C10 cycloalkyl group, preferably cyclohexyl; or a C1-C30 preferably C1-C10alkyl, more preferably C1-C5alkyl, linear or branched, saturated orpartially or totally unsaturated, the nanoparticles are arranged in the form of anetwork of different nanoparticles linked by diamondoid ligand.Advantageously, when a nanoparticle network is formed each nanoparticlehas a mean diameter, as measured from transmission electronic microscopy in thesolid state or diffusion light scattering in liquid dispersion, comprised between 0.5and 10 nm, more preferably between 0.5 and 2 nm. Advantageously, the inventorshave found that the network formation enables to control the nanoparticle size to the most reduced size. The metal of the nanoparticle is preferably, ruthenium, nickel, platinum,rhodium, cobalt, preferably nickel or ruthenium, more preferably ruthenium. Thispreferable embodiment can be combined with any of definition of the diamondoid ligand and preferred diamondoid ligand given above.The nanoparticle stabilized by the diamondoid ligand according to the presentinvention can be prepared by mixing an excess of a metallo-organic complex asmolecular precursor of nanoparticles formation with diamondoid ligand, in thepresence of a metal reducing agent (preferably hydrogen H2, LiAlH4, NaBH4, etc.) in asuitable solvent (preferably not or weakly coordinating, toluene, THF, etc.) at mildtemperature (below 100 °C) for short reaction times (preferably below 24 h). Thepreferably diamondoid ligand because of its polar sites is able to coordinate metalatoms either as a chelating agent at the surface of a single nanoparticle, or as a linker between two nanoparticle surfaces. The atomic ratio of the metal of the nanoparticle to the metal of the metallocene is greater than 5 / 1, preferably comprised between 5 / 1 and 20 / 1, preferably comprised between 8 / 1 and 15 / 1. As a typical example, the metallo-organic complex as molecular precursor ofnanoparticles formation is the bis(2-methylallyl)(1,5-cyclooctadiene)ruthenium(II)complex. The solvent is preferably the aprotic solvent tetrahydrofuran (THF). Thediamondoid ligand is preferably the 4,9-diphosphinodiamantane. The resultingsolution is preferably pressurized with 3 bars of H2 and heated under stirring at 60 °Covernight. The nanoparticles stabilized by the diamondoid ligand, according to thepresent invention, shall be distinguished from metallic complexes, which are formedfrom one metal and one ligand reaction, or when a ratio of less than five metal forone ligand is used in the synthesis.The present invention also relates to the use of a metallic nanoparticle stabilized by diamondoid ligands,wherein each diamondoid molecule is substituted by at least one group, identical ordifferent, selected in the group consisting of COOR, PR2, SR or NR2;wherein R, identical or different, represents H; a C5-C10aryl group, preferably phenyl, a C5-C10 cycloalkyl group, preferably cyclohexyl; or a C1-C30 preferably C1-C10 alkyl, more preferably C1-C5 alkyl, linear or branched, saturated or partially or totally unsaturated; preferably R is H; wherein the metal of the nanoparticle is selected in the group consisting of Fe, Ni,Co, Cr, V, Rh, Ru, Os, Re, preferably Ni or Ru; and wherein the atomic ratio of themetal of the nanoparticle to the ligand of the nanoparticle is equal or greater than 5 / 1, preferably comprised between 5 / 1 and 20 / 1, preferably comprised between 8 / 1and 15 / 1, as catalyst for the recovery of H2 by hydrolysis or solvolysis of borohydridesor borane compounds, wherein the solvent is preferentially a polar hydrogen donor, more preferentially an alcohol or water. Preferably, the metallic nanoparticle of the invention used as a catalystcontains diamondoid ligand chosen among compound having the formula- [CnHn+6-m](Z)m, wherein:^ Z is selected in the group of COOR, PR2, SR or NR2, preferably COOR, PR2,or NR2, preferably COOR or PR2; ^n is 10, 14, 18, 22, 26 or 30, preferably 10 or 14;^ m is from 1 to 10, preferably from 1 to 6, more preferably from 1 to 4,even more preferably m is 2; ^R, identical or different, represents H; a C5-C10 aryl group, preferablyphenyl, a C5-C10 cycloalkyl group, preferably cyclohexyl; or a C1-C30 preferably C1-C10 alkyl, more preferably C1-C5 alkyl, linear or branched, saturated or partially or totally unsaturated; preferably R is H,- [C10qH16q-r-s](Z)s, wherein:^ Z is selected in the group of COOR, PR2, SR or NR2, preferably COOR, PR2,or NR2, preferably COOR or PR2; ^q is 2 or 3^ r is 2 when q is 2, r is 4 when q is 3^ s is from 1 to 10, preferably from 1 to 6, more preferably from 1 to 4; evenmore preferably s is 2 ^R, identical or different, represents H; a C5-C10 aryl group, preferablyphenyl, a C5-C10 cycloalkyl group, preferably; or a C1-C30 preferably C1-C10 alkyl, more preferably C1-C5 alkyl, linear or branched, saturated or partially or totally unsaturated; preferably R is H. Preferably, Z is COOR or PR2 wherein R is as defined above, preferably R is H. Preferably, m is 2, Z is COOR or PR2 wherein R is as defined above, preferably R is H. Preferably, the diamondoid ligand of the metallic nanoparticle used as a catalyst is chosen among compound having the following formula (VIII) or (XIV) wherein Z represents at least one group, identical or different, selected in the groupconsisting of COOR, PR2, SR or NR2, preferably COOR, PR2, or NR2, preferably COORor PR2;wherein m is from 1 to 6 in formula (VIII), preferably from 1 to 4, more preferably mis 2; m is from 1 to 8 in formula (IX), preferably from 1 to 6, more preferably from 1to 4, even more preferably m is 2, m is from 1 to 10 in formula (X) to (XII), preferablyfrom 1 to 6, more preferably from 1 to 4; even more preferably m is 2. wherein in formula (XIII) and (XIV), from 1 to 10, preferably from 1 to 6, morepreferably from 1 to 4, even more preferably 2, hydrogen atom is substituted by Z,wherein R, identical or different, represents H; a C5-C10aryl group, preferably phenyl, a C5-C10 cycloalkyl group, preferably cyclohexyl; or a C1-C30 preferably C1-C10 alkyl, more preferably C1-C5alkyl, linear or branched, saturated or partially or totally unsaturated; preferably R is H. Preferably, the diamondoid ligand of the metallic nanoparticle used as a catalyst is of formula (VIII), (IX) or (XIII). Preferably, the diamondoid ligand of the metallic nanoparticle used as a catalyst is of formula (VIII), (IX) or (XIII) and m is 2. Preferably, the diamondoid ligand of the metallic nanoparticle used as a catalyst is of formula (VIII), (IX) or (XIII) and Z is COOR or PR2. Preferably, the diamondoid ligand of the metallic nanoparticle used as acatalyst is of formula (VIII), (IX) or (XIII), m is 2 and Z is COOR or PR2. Preferably, the diamondoid ligand of the metallic nanoparticle used as a catalyst is of formula (VIII), (IX) or (XIII) and Z is COOH or PH2. Preferably, the diamondoid ligand of the metallic nanoparticle used as a catalyst is of formula (VIII), (IX) or (XIII), m is 2 and Z is COOH or PH2. Preferably, the diamondoid ligand of the metallic nanoparticle used as acatalyst is of formula (VIII) or (IX). Preferably, the diamondoid ligand of the metallic nanoparticle used as a catalyst is of formula (VIII) or (IX) and m is 2. Preferably, the diamondoid ligand of the metallic nanoparticle used as a catalyst is of formula (VIII) or (IX) and Z is COOR or PR2. Preferably, the diamondoid ligand of the metallic nanoparticle used as a catalyst is of formula (VIII) or (IX), m is 2 and Z is COOR or PR2. Preferably, the diamondoid ligand of the metallic nanoparticle used as a catalyst is of formula (VIII) or (IX) and Z is COOH or PH2. Preferably, the diamondoid ligand of the metallic nanoparticle used as a catalyst is of formula (VIII) or (IX), m is 2 and Z is COOH or PH2. Preferably, the diamondoid ligand of the metallic nanoparticle used as acatalyst is of formula (VIII) or (IX) and comprises two group Z in positions 1 and 3 informula (VIII) and positions 4 et 9 in formula (IX). Positions of formula (VIII) and (IX)are illustrated below. Preferably, in the diamondoid ligand of the metallic nanoparticle used as acatalyst, Z is COOH or PR2 and preferably, R, of diamondoid ligand of the metallicnanoparticle used as a catalyst, is H.The present invention also relates to a process for recovering H2fromborohydrides or boranes compounds by hydrolysis or solvolysis in the presence of ametallic nanoparticle as defined above.Preferably, borane compounds are amine-boranes or analogous amine-boranes, hydrazine-borane.Preferably, borohydrides are sodium borohydride (NaBH4) or lithiumborohydride (LiBH4). Preferably, the analogous amine-borane is of formula NR2'H-BH3 or BH3-NR2'-(CH2)m- NR2'-BH3, wherein R' identical or different, represent H, a C5-C10 aryl group,preferably a phenyl group; or a C1-C30,preferably C1-C10alkyl, more preferably C1-C5alkyl group, linear or branched, saturated or unsaturated, m is 1, 2 or 3, preferably,the amine-borane is NH3-BH3(AB), NMeH2-BH3(methylamineborane MeAB), NMe2H-BH3(dimethyl amine-borane DMAB) or H3B-NH2CH2CH2H2N-BH3(ethylene diamine bisborane EDAB). Advantageously, the delivery of H2in the present invention can be done either by hydrolysis or solvolysis of bororohydrides, amine-boranes, analogous amine-boranes or hydrazine-borane compounds. The use of water or solvent enables tocover a large range of temperatures to implement the process. Indeed, with water itis possible to implement the process between 0 °C and 100 °C, whereas by choosinganother solvent it is possible to implement the process at lower temperature. This isof particular interest for application where the external temperature has an influence, for example in automotive field. The process can thus be carried out at a temperature comprised between thetemperature of –90 °C and 100 °C, preferably between –40 °C and 80 °C, morepreferentially between 0 °C and 30 °C, more preferentially 20 °C. Preferably, the solvent is a polar hydrogen donor. The polar hydrogen donoris preferably an alcohol. The alcohol is for example monoalcohol or polyol, preferablymonoalcohol. The monoalcohol can be chosen among ethanol or methanol. Thepolyol is for example polyalkylene glycol, preferably polyethyelene glycol. Preferably,the solvent is methanol or ethanol. The amine-borane that can be used in the present invention is not particularlylimited. Preferably, the amine-borane is of formula NR2'H→BH3 or BH3←NR2'–(CH2)m–NR2'→BH3, wherein R' identical or different, represent H, a C5-C10 aryl group, preferably phenyl; or a C1-C30, preferably C1-C10 alkyl, more preferably C1-C5 alkylgroup, linear or branched, saturated or unsaturated; m is 1, 2 or 3. Preferably, theamine-borane is NH3→BH3 (ammonia-borane, AB), NMeH2→BH3 (methylamineborane, MeAB), NMe2H→BH3 (dimethyl amine-borane, DMAB) orH3B←NH2(CH2)2H2N→BH3 (ethylene diamine bis-borane, EDAB). The hydrazine-borane according to the invention is a compound of formula N2H4–BH3 (HB).Preferably, in the process of delivery of H2 from borohydrides or boranecompounds according to the invention, the nanoparticle according to the invention is used so that the molar ratio of metal from the nanoparticle to the boranecompound is comprised between 0.0001 and 0.1, preferably between 0.001 and 0.05,more preferentially between 0.01 and 0.025. Advantageously, the nanoparticle according to the invention can be recycledand reused in the process. The recycling of the nanoparticle according to theinvention can be done by recovering the nanoparticle and then washing therecovered nanoparticles with the solvent used for the hydrolysis or solvolysis of theborohydrides or borane compounds, possibly in combination or with non-polarhydrocarbon solvent (preferably pentane). The recovery of the nanoparticleaccording to the invention can be done by any method known by the skilled personand for example by centrifugation. The invention is now described with respect to the following non limitingexamples. Materials and Methods: General synthetic conditions The solvents were purified with a solvent purification system MBraun SPS-800solvent purification system and degassed by freezing cycles. The other reagents andprecursors were purchased from Commercial Suppliers and used withoutpurifications. The glassware was oven-dried at 100°C before use. All reactions wereperformed under an atmosphere of dry argon in Schlenk tubes, Fisher−Porter bottleor two-necked flask. Bis(2-methylallyl)(1,5-cyclooctadiene)ruthenium(II) complexwas purchased from commercial sources. The ligands 1,3-Adamantanedicarboxylic,4,9-Diamantanedicarboxylic acid and 4,9-Diamantanediphosphine were synthesizedaccording to the processes described in the scientific literature, and especiallyreferring to: Min Y., Nasrallah H., Poinsot D., Lecante P., Tison Y., Martinez H., RoblinP., Falqui A., Poteau R., Rosal I., Gerber I. C., Hierso J-C., Axet M. R., Serp P. 3Druthenium nanoparticle covalent assemblies from polymantane ligands for confinedcatalysis. Chemistry of Materials 2020, 32, 2365-2378; Moncea O., Gunawan M. A.,Poinsot D., Cattey H., Becker J., Yurchenko R. I., Butova E. D., Hausmann H., SekutorM., Fokin A. A., Hierso J-C., Schreiner P. R. The Journal of Organic Chemistry. 2016,81, 8759-8769. Preparation of Ad(COOH)2 Synthesis of ligands DAd(COOH)2 and DAd(PH2)2Preparation of 4,9-Diamantanedicarboxylic Acid DAd(COOH)2 General procedure for the synthesis of Ru NPs stabilized by diamondoid ligandsThe bis(2-methylallyl)(1,5-cyclooctadiene)ruthenium(II) complex and the desiredligand were introduced in a Fisher−Porter bottle, and left in vacuum during 30minutes. Anhydrous tetrahydrofuran (THF) was then added and the mixture wasstirred 1 h under argon at room temperature. The resulting clear solution waspressurized with 3 bars of H2. The solution was kept under stirring and heatedovernight at 60 °C. After this period of time, excess of H2 was eliminated and the volume of the solvent was reduced to approximately 10 mL under vacuum. Pentanewas then added to the colloidal suspension. After several hours, a dark precipitateappeared. The solution was then filtered under argon atmosphere using a cannula,washed with pentane two times and dried under vacuum giving rise to nanoparticlesas black powder.General procedure for hydrolysis of sodium borohydride (SB) with a catalystA solution of sodium borohydride (SB, NaBH4) in water (2 mmol SB) was added to acolloidal suspension of the Ru nanoparticles (0.02 mmol Ru) in waterthermoregulated to 20 °C using syringe under stirring at 600 rpm in 25 mL double-necked round-bottomed flask. H2 generation was monitored by registering theincrease of pressure in a gas burette. Once the reaction of SB dehydrogenation wascomplete, the catalyst was recovered by centrifugation and washed 3 times withwater (i. e. solvolysis solvent) in order to use it for the next cycle. Water and a solutionof SB in water (1 mmol) were successively added to the nanoparticles and H2generation was again monitored.General procedure for ethanolysis of ammonia-borane (AB) with a catalystA solution of ammonia-borane (AB, NH3BH3) in ethanol (2 mmol AB) was added to acolloidal suspension of the Ru nanoparticles (0.02 mmol Ru) in ethanolthermoregulated to 20 °C using syringe under stirring at 600 rpm in 25 mL double-necked round-bottomed flask. H2generation was monitored by registering the increase of pressure in a gas burette. In addition, pH of the water bubbler wasmonitored to detect possible ammonia release. No detectable change in pH wasobserved. Once the reaction of AB dehydrogenation was complete, the catalyst wasrecovered by centrifugation and washed 3 times with ethanol (i.e., solvolysis solvent)in order to use it for the next cycle. Ethanol and a solution of AB in ethanol (1 mmol)were successively added to the nanoparticles and H2generation was again monitored. Preparation of non-stabilized particles (comparative examples)The bis(2-methylallyl)(1,5-cyclooctadiene)ruthenium(II) complex is pressurized with3 bars of H2 in THF at 60 °C during 18 hours. After evaporation of THF, the particlesare precipitated with pentane and recovered by centrifugation. Results of hydrolysis of sodium borohydrideThe conditions of the hydrolysis of sodium borohydride (SB) at 293 K, are thefollowing:SB: 167 mM in H2O, Ru: 0.02 mmol, 3.33 mMThe TOF (molH2.molcat−1.min−1) is calculated as follows: mmol H2 / (mmol Ru.min-1). Ru / L Assay (L=Ad(COOH)2Reaction timeTOF (min-1)-ratio (min))1 20 / 1 6.3 64.02 10 / 1 3.3 116.03 10 / 1 3.3 120.04 10 / 1 2.8 148.05 5 / 1 28 16.06 1 / 031 12.0(Comparative example) (no ligand) 7 0 / 0 (Comparative2100 0.06exampl (no catalyst)e) Results of hydrolysis of ammonia-boraneThe conditions of the hydrolysis of ammonia-borane at 293 K, are the following:AB: 187 mM in H O, Ru: 0.02 mmol, 3.33 mM2−1 −1 -1 The TOF (mol .mol .min ) is calculated as follows: mmol H / (mmol Ru.min ).H2 cat 2-1 TOF (min )Reaction timeAssay Ru / L-ratio(min) 20 / 12.5 1208 (L=Ad(COOH) )2 20 / 12.1 16392(L=DAd(COOH) ) 20 / 12.1 164102(L=DAd(PH) ) 11 10 / 1 (L=Ad(COOH)2)1.5 21012 10 / 1 (L=DAd(COOH)2)2.3 14213 10 / 1 (L=DAd(PH)2)1.3 26014 (Comparative 1 / 0 example) (no ligand)14 11Results of hydrolysis of ammonia-borane (AB) with different concentrationsThe conditions of the hydrolysis of ammonia-borane at 293 K (20 ° C), are thefollowing:AB: 6.9 M in H2O, Ru: 0.02 mmol, 34.72 mMThe TOF (molH2.molcat−1.min−1) is calculated as follows: mmol H2 / (mmol Ru.min-1). Ru / AB Ru / L Reaction time (min) TOF (min-1)Assay (L= Ad(COOH)2)- ratio 15 0.02 10 / 1 0.25 137416 0.01 10 / 1 0.34 109917 0.001 10 / 1 24 26818 0.0002 10 / 1 360 8619 0.0001 10 / 1 1380 40The results clearly show that the nanoparticles of the present invention enable todeliver great amount of H2 in reduced time (short reaction time) at very high flow-rate (high TOFs) with the use of water as solvent (examples 1 to 5, 8 to 13, 15 to 19),this in comparison to the particles non-stabilized by the diamondoid ligands(Comparative examples 6 and 14) or without catalyst (comparative example 7). Inaddition, the nanoparticles of the present invention cost-effective and more environmentally friendly by using low traces of metal (low Ru / AB molar ratio,examples 12 to 16). This is attributed in part to the organization in networks usingdiamondoid ligands that contributes to both controlling the small size of nanoparticles, and favoring their global stability. Since the process can use different solvent and for example water and alcohol, it is thus implementable whatever thetemperature, i. e. even if the temperature is well below 0 °C. At higher temperaturethe activity measured in TOF (min–1) is greatly enhanced above the present values.

Claims

Claims1. Metallic nanoparticle stabilized by diamondoid ligands,wherein each diamondoid molecule is substituted by at least one group,identical or different, selected in the group consisting of PR2;wherein R, identical or different, represents H; a C5-C10 aryl group, preferably phenyl, a C5-C10 cycloalkyl group, preferably cyclohexyl; or a C1-C30 preferablyC1-C10 alkyl, more preferably C1-C5 alkyl, linear or branched, saturated or partially or totally unsaturated; preferably R is H; wherein the metal of the nanoparticle is selected in the group consisting ofFe, Ni, Co, Cr, V, Rh, Ru, Os, Re, preferably Ni or Ru; andwherein the atomic ratio of the metal of the nanoparticle to the ligand of thenanoparticle is equal or greater than 5 / 1, preferably comprised between 5 / 1and 20 / 1, preferably comprised between 8 / 1 and 15 / 1.

2. Metallic nanoparticle according to claim 1, wherein the metal of thenanoparticle is ruthenium, nickel, platinum, rhodium or cobalt, preferablyruthenium or nickel, preferably ruthenium.

3. Metallic nanoparticle according to any one of claims 1 and 2, wherein thediamondoid ligand is chosen among compound having the formula- [CnHn+6-m](PR2)m, wherein:^ n is 10, 14, 18, 22, 26 or 30^ m is from 1 to 10, preferably from 1 to 6, more preferably from 1 to 4,even more preferably m is 2 ^R, identical or different, represents H; a C5-C10 aryl group, preferablyphenyl, a C5-C10 cycloalkyl group, preferably; or a C1-C30 preferably C1-C10 alkyl, more preferably C1-C5 alkyl, linear or branched, saturated or partially or totally unsaturated; preferably R is H;- [C10qH16q-r-s](PR2)s, wherein:^ q is 2 or 3^ r is 2 when q is 2, r is 4 when q is 3^ s is from 1 to 10, preferably from 1 to 6, more preferably from 1 to 4;even more preferably s is 2 ^R, identical or different, represents H; a C5-C10 aryl group, preferablyphenyl, a C5-C10 cycloalkyl group, preferably; or a C1-C30 preferably C1- C10 alkyl, more preferably C1-C5 alkyl, linear or branched, saturated or partially or totally unsaturated; preferably R is H.

4. Metallic nanoparticle according to any one of claims 1 to 3, wherein thediamondoid ligand is chosen among compound having the following formula (I) or (II)wherein -PR2 can occupy any position in formula (I) or (II),wherein m is from 1 to 6 in formula (I), preferably from 1 to 4, more preferably m is 2, and m is from 1 to 8 in formula (II), preferably from 1 to 6, more preferably from 1 to 4, even more preferably m is 2, wherein R, identical or different, represents H; a C5-C10 aryl group, preferably phenyl, a C5-C10 cycloalkyl group, preferably cyclohexyl; or a C1-C30 preferablyC1-C10 alkyl, more preferably C1-C5 alkyl, linear or branched, saturated or partially or totally unsaturated; preferably R is H.

5. Metallic nanoparticle according to any one of claims 1 to 4, wherein:– m is 2; or- R is H; or– m is 2 and R is H.

6. Use of a metallic nanoparticle stabilized by diamondoid ligands,Wherein each diamondoid molecule is substituted by at least one group,identical or different, selected in the group consisting of COOR, SR, PR2 or NR2;wherein R, identical or different, represents H; a C5-C10 aryl group, preferably phenyl, a C5-C10 cycloalkyl group, preferably cyclohexyl; or a C1-C30 preferably C1-C10 alkyl, more preferably C1-C5 alkyl, linear or branched, saturated or partially or totally unsaturated; preferably R is H;wherein the metal of the nanoparticle is selected in the group consisting of Fe, Ni, Co, Cr, V, Rh, Ru, Os, Re, preferably Ni or Ru; and wherein the atomic ratio of the metal of the nanoparticle to the ligand of the nanoparticle is equal or greater than 5 / 1, preferably comprised between 5 / 1 and 20 / 1, preferably comprised between 8 / 1 and 15 / 1, as catalyst for the recovery of H2by hydrolysis or solvolysis of borohydrides or borane compounds, wherein the solvent is preferentially a polar hydrogen donor, more preferentially an alcohol or water.

7. Use according to claim 6, wherein the diamondoid ligand is chosen amongcompound having the formula -[CnHn+6-m](Z)m, wherein:^ Z is selected in the group of COOR, PR2, SR or NR2^ n is 10, 14, 18, 22, 26 or 30^ m is from 1 to 10, preferably from 1 to 6, more preferably from 1 to 4,even more preferably m is 2 ^R, identical or different, represents H; a C5-C10 aryl group, preferablyphenyl, a C5-C10 cycloalkyl group, preferably; or a C1-C30 preferably C1-C10 alkyl, more preferably C1-C5 alkyl, linear or branched, saturated or unsaturated; preferably R is H,- [C10qH16q-r-s](Z)s, wherein:^ Z is selected in the group of COOR, PR2, SR or NR2^ q is 2 or 3^ r is 2 when q is 2, r is 4 when q is 3^ s is from 1 to 10, preferably from 1 to 6, more preferably from 1 to 4;even more preferably s is 2 ^R, identical or different, represents H; a C5-C10 aryl group, preferablyphenyl, a C5-C10cycloalkyl group, preferably; or a C1-C30preferably C1- C10alkyl, more preferably C1-C5alkyl, linear or branched, saturated or partially or totally unsaturated; preferably R is H.

8. Use according to claim 7, wherein the diamondoid ligand is chosen amongcompound having the following formula (VIII) or (IX)Wherein: ^Z is selected in the group of COOR, PR2, SR or NR2, preferably COOR or PR2^ wherein m is from 1 to 6 in formula (I), preferably from 1 to 4, morepreferably m is 2, and m is from 1 to 8 in formula (II), preferably from 1 to 6, more preferably from 1 to 4, even more preferably m is 2, ^R, identical or different, represents H; a C5-C10 aryl group, preferablyphenyl, a C5-C10 cycloalkyl group, preferably cyclohexyl; or a C1-C30 preferably C1-C10 alkyl, more preferably C1-C5 alkyl, linear or branched, saturated or partially or totally unsaturated; preferably R is H.

9. Use according to claim 7 or 8 whereinm is 2; or Z is COOR or PR2; orZ is COOH or PH2; or m is 2 and Z is COOR or PR2; or m is 2 and Z is COOH or PH2.

10. Process for recovering H2 from borohydrides or borane compounds byhydrolysis or solvolysis in the presence of a metallic nanoparticle as definedin any one of claim 1 to 9.

11. Use according to any one of claim 6 to 9, or process according to claim 10,wherein boranes compounds are amine-boranes or analogous amine-boranes, hydrazine-borane.

12. Use according to any one of claim 6 to 9 and 11, or process according to anyone of claim 10 or 11, wherein the borohydride is sodium borohydride(NaBH4) or lithium borohydride (LiBH4).

13. Use according to any one of claim 6 to 9, 11 and 12, or process according toany one of claim 10 to 12 wherein the analogous amine-borane is of formula NR2'H-BH3 or BH3-NR2'-(CH2)m- NR2'-BH3, wherein R' identical or different,represent H, a C5-C10 aryl group, preferably a phenyl group; or a C1-C30, preferably C1-C10alkyl, more preferably C1-C5alkyl group, linear or branched, saturated or unsaturated, m is 1, 2 or 3, preferably, the amine-borane is NH3- BH3 (AB), NMeH2-BH3 (methylamineborane MeAB), NMe2H-BH3 (dimethyl amine-borane DMAB) or H3B-NH2CH2CH2H2N-BH3(ethylene diamine bisborane EDAB).

14. Use according to any one of claim 6 to 9 and 11 to 13, or process according toany one of claim 10 to 13, wherein the solvolysis is carried out using ethanol.

15. Process according to any one of claim 10 to 14, wherein the reaction is carriedout at a temperature comprised between –90 °C and 100 °C, preferablybetween –40 °C and 80 °C, more preferentially between 0 °C and 30 °C, morepreferentially 20 °C.

16. Process according to any one of claim 10 to 15, wherein the reaction is carriedout so that the molar ratio of metal from the nanoparticle to the boranecompound is comprised between 0.0001 and 0.1, preferably between 0.001and 0.05, more preferentially between 0.01 and 0.025.

17. Process according to any one of claims 10 to 16 further comprises a step ofrecycling the nanoparticles, preferably the recycling is carried out by recovering the nanoparticles and washing the recovered nanoparticles with the solvent used for the hydrolysis or solvolysis of the borane compound.

Images