Selective Dehydrogenation Of Formic Acid Research Articles

Hydrogen Generation from Additive-Free Formic Acid Decomposition Under Mild Conditions by Pd/C: Experimental and DFT Studies

Safe and efficient hydrogen generation and storage has received much attention in recent years. Herein, a commercial 5 wt% Pd/C catalyst has been investigated for the catalytic, additive-free decomposition of formic acid at mild conditions, and the experimental parameters affecting the process systematically have been investigated and optimised. The 5 wt% Pd/C catalyst exhibited a remarkable 99.9% H2 selectivity and a high catalytic activity (TOF = 1136 h−1) at 30 °C toward the selective dehydrogenation of formic acid to H2 and CO2. The present commercial catalyst demonstrates to be a promising candidate for the efficient in-situ hydrogen generation at mild conditions possibiliting practical applications of formic acid systems on fuel cells. Finally DFT studies have been carried out to provide insights into the reactivity and decomposition of formic acid along with the two-reaction pathways on the Pd (111) surface.

A Stable Nanocobalt Catalyst with Highly Dispersed CoNx Active Sites for the Selective Dehydrogenation of Formic Acid

AbstractNovel nanostructured catalysts with highly dispersed cobalt have been synthesized by the pyrolysis of metal phenanthroline complexes. Materials with significantly different properties were obtained by simply tuning the metal/ligand ratio. The catalytic potential of this class of compounds is shown by the first example of the dehydrogenation of formic acid under the catalysis of atomically dispersed cobalt. From TEM, XPS, and XRD characterization, KSCN poisoning, and acid leaching, the formation of CoNx species as the active site seems key to the success of this reaction. Excellent stability and recyclability make this new catalyst also attractive for other applications.

A Stable Nanocobalt Catalyst with Highly Dispersed CoNx Active Sites for the Selective Dehydrogenation of Formic Acid.

Novel nanostructured catalysts with highly dispersed cobalt have been synthesized by the pyrolysis of metal phenanthroline complexes. Materials with significantly different properties were obtained by simply tuning the metal/ligand ratio. The catalytic potential of this class of compounds is shown by the first example of the dehydrogenation of formic acid under the catalysis of atomically dispersed cobalt. From TEM, XPS, and XRD characterization, KSCN poisoning, and acid leaching, the formation of CoNx species as the active site seems key to the success of this reaction. Excellent stability and recyclability make this new catalyst also attractive for other applications.

Selectivity Effects in Bimetallic Catalysis: Role of the Metal Sites in the Decomposition of Formic Acid into H2 and CO2 by the Coinage Metal Binuclear Complexes [dppmMM′(H)]+

AbstractDesign of new bimetallic catalysts requires an understanding of how cooperative effects of the metal sites influences reactivity. Here we show how switching one or both of the silver atoms in binuclear silver hydride cations, [dppmAg2(H)]+ (dppm=1,1‐Bis(diphenylphosphino)‐methane), with all combinations of copper and/or gold maintains selective dehydrogenation of formic acid, enhancing reactivity by up to 2 orders of magnitude. This is a key step in the selective, catalyzed extrusion of carbon dioxide from formic acid, HO2CH, with important applications in hydrogen storage and in situ generation of H2. Decarboxylation of [dppmMM′(O2CH)]+ through collision induced dissociation regenerates [dppmMM′(H)]+. DFT calculations provide insights into these cooperative effects. The copper homobinuclear catalyst performs best overall.

Selective Formic Acid Dehydrogenation Catalyzed by Fe-PNP Pincer Complexes Based on the 2,6-Diaminopyridine Scaffold

Fe(II) hydrido carbonyl complexes supported by PNP pincer ligands based on the 2,6-diaminopyridine scaffold were studied as homogeneous, non-precious-metal-based catalysts for selective formic acid dehydrogenation to hydrogen and carbon dioxide, reaching quantitative yields and high TONs under mild reaction conditions.

Ionic liquid-modified fibrous silica microspheres loaded with PbS nanoparticles and their enhanced catalytic activity and reusability for the hydrogen production by selective dehydrogenation of formic acid

A new type of catalyst based on the ionic liquid (IL) modified fibrous nano-silica material KCC-1, with a high surface area, as the support and PbS nanoparticles (NPs) as the active sites (KCC-1/IL/PbS), has been successfully prepared through a facile and environmentally-friendly approach and characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA). The synthesized catalyst exhibited high catalytic performance in the selective dehydrogenation of aqueous solutions of HCOOH/HCOONa to H2 and CO2 gas due to not only the unique dendritic fibrous morphology of the support, which made the active sites accessible, but also the synergistic effect between KCC-1/IL and the small PbS NPs. Additionally, KCC-1/IL/PbS had good recyclability, mainly attributed to the IL groups, which acted as robust anchors to avoid PbS NP leaching from the support. This synthetic method provides a green way to effectively prepare low cost PbS based catalysts and is promising for the development of other useful materials.

An active, stable and recyclable Ru(ii) tetraphosphine-based catalytic system for hydrogen production by selective formic acid dehydrogenation

Efficient catalytic formic acid dehydrogenation was achieved with Ru(ii) complexes ofmeso-tetraphos-1 under batch and continuous feed conditions.

Microscopic View of the Active Sites for Selective Dehydrogenation of Formic Acid on Cu(111)

Formic acid is an important molecule, due to its potential for hydrogen storage and the role of formate in methanol synthesis. Formic acid can decompose on metals and oxides via dehydrogenation or dehydration, although dehydrogenation is preferred for most applications. These two pathways are linked via the water–gas shift reaction (WGSR), making them hard to separate, and debate over the mechanisms still exists. Cu catalysts are known to selectively decompose formic acid via dehydrogenation to produce CO2 and H2. Formic acid’s interaction with Cu(110) has been extensively studied, but despite the (111) facet being predominant in many nanoparticles, Cu(111) has received little attention. Using temperature-programmed desorption/reaction (TPD/R) and scanning tunneling microscopy (STM), we have probed key steps in the decomposition of formic acid on Cu(111) at the atomic scale, observing intact adsorption and surface intermediates, as well as the surface after product desorption. Our model system allows us t...

Interfacial Effects in PdAg Bimetallic Nanosheets for Selective Dehydrogenation of Formic Acid

AbstractTwo‐dimensional ultrathin PdAg bimetallic nanosheets are fabricated and used as model catalysts for understanding the synergetic effects in bimetallic nanocatalysts. The ultrathin nature of the nanosheets allows us to probe the electronic and geometric structures using XPS and X‐ray absorption spectroscopy. The as‐prepared bimetallic nanosheets show high catalytic activity for selective dehydrogenation of formic acid, especially when the Ag/Pd ratio reaches 1. The superior activity is attributed to the electronic and geometric effect generated from the Pd–Ag interfaces in the catalysts. Our studies reveal increased bond distances of Pd–Pd and decreased Ag–Ag bond lengths in the PdAg bimetallic nanosheets. Pd is electronically promoted by Ag to give enhanced catalysis. Moreover, the geometric effect generated from the PdAg alloyed surface enhances the catalysis by suppressing CO poisoning on the catalysts, which is confirmed by electrochemical FTIR measurements.

Hydrogen from Formic Acid via Its Selective Disproportionation over Nanodomain-Modified Zeolites

Sodium germanate is a nontransition-metal catalyst that is active in the selective dehydrogenation of formic acid. However, bulk sodium germanate has a very low surface area, limiting the availability of the germanate sites for catalysis. The dispersion of germanate in the zeolite ZSM-5 has been investigated both computationally and experimentally as a method for the provision of greater surface area and, therefore, higher activity per germanate site. Nanodomain islets of germanate dispersed in the germanium ZSM-5 zeolite invert selectivity from dehydration (in ZSM-5) to dehydrogenation of formic acid, potentially making Na-Ge-ZSM-5 a cost-effective catalyst for releasing hydrogen from formic acid.

Hydrogen from formic acid through its selective disproportionation over sodium germanate--a non-transition-metal catalysis system.

A robust catalyst for the selective dehydrogenation of formic acid to liberate hydrogen gas has been designed computationally, and also successfully demonstrated experimentally. This is the first such catalyst not based on transition metals, and it exhibits very encouraging performance. It represents an important step towards the use of renewable formic acid as a hydrogen-storage and transport vector in fuel and energy applications.

Hydrogen from Formic Acid through Its Selective Disproportionation over Sodium Germanate—A Non‐Transition‐Metal Catalysis System

AbstractA robust catalyst for the selective dehydrogenation of formic acid to liberate hydrogen gas has been designed computationally, and also successfully demonstrated experimentally. This is the first such catalyst not based on transition metals, and it exhibits very encouraging performance. It represents an important step towards the use of renewable formic acid as a hydrogen‐storage and transport vector in fuel and energy applications.

Hydrogen generation from formic acid decomposition at room temperature using a NiAuPd alloy nanocatalyst

Formic acid has been widely regarded as a safe and sustainable hydrogen storage material. Despite tremendous efforts, developing low-noble-metal-loading material with high activity for the dehydrogenation of formic acid remains a great challenge. Here, carbon supported highly homogeneous trimetallic NiAuPd alloy nanoparticles are prepared and employed as catalyst for the selective dehydrogenation of formic acid. Unexpectedly, at Ni molar contents as high as 40%, the resultant Ni0.40Au0.15Pd0.45/C exhibits high activity and 100% hydrogen selectivity for hydrogen generation from formic acid aqueous solution without any additives even at 298 K. Such a low-noble-metal-loading catalyst with high activity may greatly encourage the practical application of formic acid as a hydrogen storage material.

Aluminium–ligand cooperation promotes selective dehydrogenation of formic acid to H2 and CO2

Selective conversion of formic acid to H2 and CO2 is catalysed by a molecular aluminum complex. Metal–ligand cooperative interactions stabilize a transition state for an outer-sphere β-hydride abstraction mechanism for catalysis.

Formic acid dehydrogenation catalysed by ruthenium complexes bearing the tripodal ligands triphos and NP3

The selective formic acid dehydrogenation to a mixture of CO(2) and H(2) was achieved with moderate to good productivities in the presence of homogeneous Ru catalysts bearing the polydentate tripodal ligands 1,1,1-tris-(diphenylphosphinomethyl)ethane (triphos) and tris-[2-(diphenylphosphino)ethyl]amine (NP(3)), either made in situ from suitable Ru(III) precursors or as molecular complexes. Preliminary mechanistic studies highlighting subtle differences due to ligand effects in the corresponding systems under study are also presented.

Hydrogen Storage in Formic Acid - Amine Adducts.

Formic acid, containing 4.4 wt% of hydrogen, is a non-toxic liquid at ambient temperature and therefore an ideal candidate as potential hydrogen storage material. Formic acid can be generated via catalytic hydrogenation of CO2 or bicarbonate in the presence of an amine with suitable ruthenium catalysts. In addition selective dehydrogenation of formic acid amine adducts can be carried out at ambient temperatures with either ruthenium phosphine catalyst systems as well as iron-based catalysts. In detail we obtained with the [RuCl2(benzene)]2/dppe catalyst system a remarkable TON of 260,000 at room temperature. Moreover applying Fe3(CO)12 together with tribenzylphosphine and 2,2':6',2"-terpyridine under visible light irradiation a TON of 1266 was obtained, which is the highest activity known to date for selective dehydrogenation of formic acid applying non-precious metal catalysts.

Low activation energy dehydrogenation of aqueous formic acid on platinum–ruthenium–bismuth oxide at near ambient temperature and pressure

Highly selective dehydrogenation of formic acid in water was observed at near ambient temperature on a metal/metal oxide catalyst composed of platinum ruthenium and bismuth with a low activation energy of 37.3 kJ mol(-1).