Organic Hydrogen Carriers Research Articles

Thermodynamic evaluations of the acceptorless dehydrogenation and hydrogenation of pre-aromatic and aromatic N-heterocycles in acetonitrile.

N-heterocycles are important chemical hydrogen-storage materials, and the acceptorless dehydrogenation and hydrogenation of N-heterocycles as organic hydrogen carriers have been widely studied, with the main focus on the catalyst synthesis and design, investigation of the redox mechanisms, and extension of substrate scope. In this work, the Gibbs free energies of the dehydrogenation of pre-aromatic N-heterocycles (YH2) and the hydrogenation of aromatic N-heterocycles (Y), i.e., ΔGH2R(YH2) and ΔGH2A(Y), were derived by constructing thermodynamic cycles using Hess' law. The thermodynamic abilities for the acceptorless dehydrogenation and hydrogenation of 78 pre-aromatic N-heterocycles (YH2) and related 78 aromatic N-heterocycles (Y) were well evaluated and discussed in acetonitrile. Moreover, the applications of the two thermodynamic parameters in identifying pre-aromatic N-heterocycles possessing reversible dehydrogenation and hydrogenation properties and the selection of the pre-aromatic N-heterocyclic hydrogen reductants in catalytic hydrogenation were considered and are discussed in detail. Undoubtedly, this work focuses on two new thermodynamic parameters of pre-aromatic and aromatic N-heterocycles, namely ΔGH2R(YH2) and ΔGH2A(Y), which are important supplements to our previous work to offer precise insights into the chemical hydrogen storage and hydrogenation reactions of pre-aromatic and aromatic N-heterocycles.

A new hydrogenation-coupling approach for supra-equilibrium conversion in a water–gas shift reaction: Simultaneous hydrogen generation and chemical storage

This work reports a practical system of hydrogenation-coupled water–gas shift reaction (HC-WGSR) for simultaneous hydrogen production and storage. The performance of the HC-WGSR system was predicted through thermodynamic simulation. The proof-of-concept tandem water–gas shift and propene hydrogenation strategy was successfully demonstrated using a bifunctional catalyst. The hydrogen produced from the WGSR was successfully stored in propane simultaneously, and the overall CO conversion of nearly 100% overcame the equilibrium limitation of the WGSR over a wide range of space velocities (3000 - 6000 h−1) at 200 °C and 1 bar. This study demonstrated that the in situ removal/storage of H2 using the hydrogenation-coupling approach is promising even in a CO2-rich environment (20% CO2). The new approach shall see a great opportunity in using organic hydrogen carriers, e.g., benzene, toluene, N-ethylcarbazole, to expand the industrial applications, underpinning the global supply chain for hydrogen energy.

Reversible Hydrogenation–Dehydrogenation of Acetylpyridine-Pd-MIL-101(Cr) for Chemical Hydrogen Storage

3-Acetylpyridine (AcP), as an organic hydrogen carrier, and Pd nanoparticles, as a catalyst, were incorporated into MIL-101(Cr) for chemical hydrogen storage. AcP was first grafted into MIL-101(Cr)...

Unraveling Metal/Pincer Ligand Effects in the Catalytic Hydrogenation of Carbon Dioxide to Formate

The hydrogenation of carbon dioxide to formate is an intriguing reaction from both an environmental and an energy perspective, primarily due to the prospective uses of the product as a platform chemical in numerous applications such as an organic hydrogen carrier. Although several transition-metal-based catalysts have been shown to facilitate this chemical transformation, few guidelines exist on how best to tune the catalysts in order to achieve maximum activity. Here, we use linear scaling relationships and molecular volcano plots to gauge the potential of different metal–pincer catalysts for the aforementioned reaction. Analysis of combinations of five metals (Ru, Os, Co, Rh, and Ir) and seven tridentate pincer-type ligands reveals several complexes lying near the volcano top, suggesting that these species have nearly ideal energetic profiles for facilitating the hydrogenation reaction. In particular, catalysts bearing group 9 metal centers (Ir, Rh, Co) with π-acidic ligands provide a clear route to imp...

ChemInform Abstract: A Novel and Convenient Way of Hydride Formation of Rare Earth Intermetallic Compounds by Reaction with Organic Hydrogen Carriers.

AbstractIt is shown that hydrogen transfer reaction occurs between R2Co7 (R: rare earth metal) and organic hydrogen carriers such as MeOH, EtOH, or 2‐propanol.

A novel and convenient way of hydride formation of rare earth intermetallic compounds by reaction with organic hydrogen carriers

A novel and convenient way of hydride formation of rare earth intermetallic compounds by reaction with organic hydrogen carriers