PROGRAMMA DI RICERCA
Direzione Generale
Ufficio Accordi e Relazioni Internazionali
ACCORDO CNR/RFBR -
PROGRAMMA DI RICERCA
Stato progetto:Rinnovo
Titolo italiano: STOCCAGGIO CHIMICO DI IDROGENO IN AMMONIACA-BORANO (AB): SINTESI DI CATALIZZATORI DI DEIDROGENAZIONE DI AB E STUDI COMBINATI SPETTROSCOPICI/COMPUTAZIONALI DEL MECCANISMO DI RILASCIO DI IDROGENO
Titolo inglese: CHEMICAL HYDROGEN STORAGE THROUGH AMMONIA- BORANE (AB): SYNTHESIS OF AB DEHYDROGENATION CATALYSTS AND COMBINED SPECTROSCOPIC/COMPUTATIONAL STUDIES OF THE MECHANISM OF HYDROGEN RELEASE
Dipartimento di afferenza del progetto di ricerca: Scienze chimiche e tecnologie dei materiali
Proposta di ricerca: The transition from a global economy based on the unsustainable exploitation of fossil fuels to produce energy to a new lifestyle founded on the widespread use of hydrogen as a green energy vector is generally invoked to satisfy the growing energy needs for the whole mankind in the second part of this century. As it is generally accepted, the development of a mature and diffuse "hydrogen economy" is hampered by two severe drawbacks: (i) a "sustainable" hydrogen production not only from coal or natural gas but mainly from renewable energies (such as solar, biomass and wind); (ii) the development of a reliable and cheap hydrogen transportation system. Unfortunately, hydrogen transportation and handling is difficult, making its use for any kind of renewable energy device rather problematic. To solve this problem, hydrogen must be stored into chemical compounds, which easily release hydrogen on demand. Recently, B-N compounds (amine- boranes) have attracted considerable interest in this regard, as they offer an appropriate balance of volumetric and gravimetric energy densities. Among the most promising materials in this field, a special role is taken by the lightweight and hydrogen-rich species ammonia-borane (NH3BH3, AB, 19.3 max.% wt. H). AB is non-flammable and stable under standard conditions; its dehydrogenation/hydrolysis mediated by organometallic catalysts offers the potential to tune both rate and extent of H2 release. Over the past five years, relatively expensive transition metals (Ir, Rh, Ru, Pd) have been exploited as homogeneous catalysts when combined with suitable ligand sets. However, as the final application of these catalysts is the transportation sector, the development of cost-effective catalytic systems based on more Earth abundant metals (e.g. Mn, Fe, Co, Ni, Cu, Zn) are warmly encouraged to make the process really sustainable. On the other hand, heterogeneous catalysis, based on both metallic (supported metal nanoparticles, Metal- Organic Frameworks) and non-metallic (light-heterodoped nanocarbons) materials have been used to promote AB thermal dehydrogenation to produce H2 in a sustainable manner. The combination of AB nanoconfinement into porous and ordered scaffolds (that prevents
AB oligomerization and reduces the amount of undesired side-products like ammonia, diborane or borazine) with the presence of exposed metal sites (that strongly interact with AB polar B-H and N-H bonds) represents a convenient and commonly pursued approach to the design of an optimal AB dehydrogenation catalyst featuring the target of reducing the minimum H2 release temperature with respect to pristine AB (that occurs at around 100 °C) and increasing release rates and H2 yields in terms of wt. H %. One main challenge of modern heterogeneous catalysis is re-thinking fundamental metal-based catalytic processes in light of tailored metal-free catalytic architectures, designed and fabricated from cheap and easily accessible building blocks. The catalysts to be studied are both homogeneous and heterogeneous in nature and will basically consist in: (i) late transition metal (NCP) pincer hydrides (with particular attention to complexes of 3d metals); (ii) metal-free N-doped carbon nanotubes (N-CNTs). In both cases the assorted N-containing heterocycles will be used as part of the pincer ligand or as modifiers of the nanotubes outer surface. Preliminary data collected by the Italian team show their potential for the project purposes. The polytopic dissymmetrical (NCP) pincer ligands were designed recently at ICCOM and will be used to prepare novel metal hydride complexes as the homogeneous single-site catalysts. Their structure, reactivity and interaction with AB will be studied at both INEOS and ICCOM laboratories. Variable temperature spectroscopic [multinuclear (1H, 13C, 31P, 11B) NMR, IR, UV-Visible] measurements and quantum-chemical calculations will be performed to study the reaction mechanism, possibly leading to H2 formation and evolution after an initial dihydrogen bonding (DHB) between the hydridic and protic H atoms. The data on structure and properties of various reaction intermediates will be obtained, together with the kinetic and thermodynamic parameters of each step. Attempts to isolate the reaction intermediates identified during these studies will be made (if stable at ambient conditions). The metal atom influence on structure, vibrational frequencies, electron density distribution and reactivity of the starting catalysts will be acquired. Special attention will be paid to the study of the solvent effects. The heterogeneously-catalyzed AB dehydrogenation by selected N-CNTs will be performed after an initial nanotube impregnation with AB solutions (at a given molarity) in THF at room temperature, followed by solvent removal.
The as-prepared AB@N-CNT solid will be characterized through the ordinary solid-state techniques (powder X-ray diffraction, TG-MS, IR, TEM microscopy, 11B solid-state NMR, BET surface area measurements). The thermal H2 release will be monitored via TPD-MS to determine the release temperatures and yields. The results will be compared with those coming from pristine AB, to clarify the effect of its nanoconfinement into the heterogeneous catalyst. Quantum-chemical calculations will be also exploited to gain insights into the AB@N-CNT interaction mechanism and overall energetics [evaluation of the reaction thermodynamics (DG) and kinetics (DG#, Transition States)].
Obiettivi:
The objective of this bilateral CNR/RFBR project is the preparation of novel homogeneous and heterogeneous AB dehydrogenation catalysts and the analysis of their catalytic performance, using a comprehensive approach based on the combination of experimental and theoretical methods. A special emphasis will be put on the assessment of the role of the intermolecular dihydrogen bonding that preceeds the H2 release and influence the final reaction pathway. In addition, the effect of the type of substituents on the pincer ligands or the N-containing dangling groups on CNTs on the H2 release temperatures, kinetics and yields will be rationalized, with the aim of creating second-generation systems with improved efficiency. The project involves the Istituto di Chimica dei Composti Organometallici of Florence (ICCOM) of the National Research Council (CNR) and the Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences (INEOS) of Moscow. The participants are largely experienced in this research field, and have a sound track of highly positive international collaborations including the participation, either as Coordinating or Participating team, in numerous international projects (4th RFP, 5th RFP, 6th RFP, INTAS, NATO, GDRI). This collaboration has already produced 11 joint publications and over 25 joint presentations at International and
National meetings.
PIANIFICAZIONE DEL LAVORO
Piano di lavoro primo anno: 1) Synthesis and characterization (single crystal X-ray diffraction, NMR, IR) of the homogeneous catalysts: group 8 (FeII, RuII, OsII) transition metal hydrides bearing asymmetrical (NCP) pincer ligands with pyrazole and thiazole substituents. 2) Spectroscopic (VT-IR, VT-NMR) and theoretical (DFT) studies of their relative basicity/acidity through reactions with simple OH or NH acids. 3) Initial tests of the complexes as homogeneous catalysts of AB and amine-boranes (NHR2BH3, NH2RBH3; R
= cyclic/linear alkyl groups) dehydrogenation. Isolation and characterization of the stable intermediates (if present). Measurements of the equivalents of released H2 (when occurring). 4) Synthesis of the heterogeneous catalysts: impregnation of tailored pyridine- decorated carbon nanotubes (N-CNTs) with AB solutions in THF to prepare AB@N-CNT; characterization of the as-synthesized material (powder X-ray diffraction, TG-MS, IR, TEM microscopy, 11B NMR-MAS, BET surface area measurements).
Piano di lavoro secondo anno: 1) Synthesis and characterization of group 10 (XxXX, PdII, PtII) transition metal hydrides bearing asymmetrical (NCP) pincer ligands with pyrazole and thiazole substituents. 2) Initial tests of these complexes as homogeneous catalysts of AB and amine-boranes dehydrogenation. Isolation and characterization of the stable intermediates. Measurements of the equivalents of released H2. 3) Computational screening of the H2 evolution mechanism, based on the experimental results collected. Evaluation of the thermodynamic (DG) and kinetic (DG#) reaction parameters. Calculation of the Transition States (TS) of the process. 4) Thermal H2 production from AB@N-CNT monitored via TPD-MS and VT-IR (solid state) to determine the release reaction temperatures and yields. 5) Spectroscopic investigation of AB interaction with selected heterocycles dangling from the CNT surface (pyridines, pyrroles),to understand the mechanism of hydrogen production.
Piano di lavoro terzo anno: 1) Use of differently substituted pincer (NCP) ligands (either by changing their side-arms or by introducing different groups on the central phenyl ring) for the creation of second generation of catalysts, with the same metal sets. Analysis of their reaction with acids and AB/amine-boranes. 2) Analysis of the dependence of the hydrides activity (TON, TOF) on the metal, ligand properties. Comparison to known (PCP) pincer hydrides. In depth study of the AB dehydrogenation kinetics as a function of temperature, concentration and solvent. 3) Additional impregnation procedures with AB solutions in THF of novel N-CNTs bearing different N-containing dangling groups (pyrroles, quaternary nitrogens) or in situ N-doped systems, to get a second generation of AB@N- CNT materials; monitoring of their H2 release temperatures and rates via TPD-MS and VT- IR, and comparison with the data of pristine AB. Assessment of the best-performing catalyst.
COLLABORATORI ITALIANI
Cognome: ROSSIN Nome: XXXXXX
Codice terzo: 0
Matricola: 11654
Codice fiscale: XXXXXX00X00X000X
Istituto: ISTITUTO DI CHIMICA DEI COMPOSTI ORGANO METALLICI
Rapporto CNR: Dipendente
Posizione: III LIVELLO - RICERCATORE
Curriculum allegato:CV_5_pagine_rossin.pdf
Cognome: GIAMBASTIANI Nome: XXXXXXXX
Codice terzo: 0
Matricola: 8701
Codice fiscale: XXXXXX00X00X000X
Istituto: ISTITUTO DI CHIMICA DEI COMPOSTI ORGANO METALLICI
Rapporto CNR: Dipendente
Posizione: II LIVELLO - I RICERCATORE
Email: x.xxxxxxxxxxxx@xxxxx.xxx.xx
Curriculum allegato:CV_breve Xxxxxxxxxxxx Xxxxxxxx.pdf
Cognome: LUCONI Nome: LAPO
Codice terzo: 115004
Matricola: 0
Codice fiscale: XXXXXX00X00X000X
Istituto: ISTITUTO DI CHIMICA DEI COMPOSTI ORGANO METALLICI
Rapporto CNR: Personale esterno Posizione: ASSEGNISTA
Email: xxxx.xxxxxx@xxxxx.xxx.xx
Selezionato con procedura comparativa: No Curriculum allegato:European CV Xxxx Xxxxxx-1.pdf
Cognome: TUCI Nome: GIULIA
Codice terzo: 152592
Matricola: 0
Codice fiscale: XXXXXX00X00X000X
Istituto: ISTITUTO DI CHIMICA DEI COMPOSTI ORGANO METALLICI
Rapporto CNR: Personale esterno Posizione: ASSEGNISTA
Email: xxxxxx.xxxx@xxxxx.xxx.xx
Selezionato con procedura comparativa: No Curriculum allegato:CVTemplate_IT_Giulia.pdf
COLLABORATORI STRANIERI
Cognome: Belkova Nome: Xxxxxxx Xxxxxxxxx: Ricercatore
Curriculum allegato: NBelkova_CV-european-format.pdf
Cognome: Xxxxxxxx Xxxx: Xxxx Xxxxxxxxx: Ricercatore
Curriculum allegato: CV-european-format_filippov-2014.pdf
Cognome: Golub Nome: Xxxx Xxxxxxxxx: Dottorando
Curriculum allegato: Xxxxx Xxxx CV eu.pdf
Cognome: Xxxxxxxx Nome: Xxxxxxxxx Xxxxxxxxx: Ricercatore
Curriculum allegato: CV_Kozinets.pdf
Cognome: Osipova Nome: Xxxxx Xxxxxxxxx: Tecnico
Curriculum allegato: CV Osipova-european-format.pdf
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