Dehydrogenation Of Formic Acid Research Articles

Dehydrogenation of Formic Acid Catalyzed by an Osmium-Polyhydride: Relevance of Acid Assistance in the CO2 Formation Stage

Dehydrogenation of Formic Acid Catalyzed by an Osmium-Polyhydride: Relevance of Acid Assistance in the CO₂ Formation Stage

Selective Photocatalytic Dehydrogenation of Formic Acid on Graphite Carbon Nitride with Dual-Sited Cobalt and Platinum Cocatalysts

Selective Photocatalytic Dehydrogenation of Formic Acid on Graphite Carbon Nitride with Dual-Sited Cobalt and Platinum Cocatalysts

Unveiling proton-responsive sites and reaction mechanisms in formic acid dehydrogenation catalyzed by Cp*Ir(III)-Pyridylpyrrole complexes: A DFT study

Transition metal catalysts based on proton-responsive ligands are crucial in the realm of chemical hydrogen storage. Nevertheless, the existence of multiple proton-responsive active sites on the ligand adds complexity to the mechanism, limiting our understanding of mechanistic preferences. In this study, density functional theory calculations are used to clarify the mechanistic preferences of iridium catalysts with multiple proton-responsive sites on the ligand for formic acid dehydrogenation. The calculated results show that, with the assistance of the α carbon atom (C2) of the pyrrole ligand site, the catalyst undergoes through an inner-sphere stepwise dehydrogenation mechanism. Moreover, the proton shuttle mechanism efficiently reduces the activation energy needed for H2 production, and solvent-assisted dehydrogenation shows lower energy barriers than substrate-assisted dehydrogenation. The reasons for mechanistic selectivity are further elucidated through Fukui function analysis, molecular plane parameter analysis, and the distortion-interaction model. These findings are anticipated to establish a theoretical foundation for the future design of high-performance catalysts for formic acid dehydrogenation.

Expanding the Scope of Aluminum Chemistry with Noninnocent Ligands.

ConspectusAluminum is the most abundant metal in the earth's crust at 8%, and it is also widely available domestically in many countries worldwide, which ensures a stable supply chain. To further the applications of aluminum (Al), such as in catalysis and electronic and energy storage materials, there has been significant interest in the synthesis and characterization of new Al coordination compounds that can support electron transfer (ET) and proton transfer (PT) chemistry. This has been achieved using redox and chemically noninnocent ligands (NILs) combined with the highly stable M(III) oxidation state of Al and in some cases the heavier group 13 ions, Ga and In.When ligands participate in redox chemistry or facilitate the breaking or making of new bonds, they are often termed redox or chemically noninnocent, respectively. Al(III) in particular supports rich ligand-based redox chemistry because it is so redox inert and will support the ligand across many charge and protonation states without entering into the reaction chemistry. To a lesser extent, we have reported on the heavier group 13 elements Ga and In, and this chemistry will also be included in this Account, where available.This Account is arranged into two technical sections, which are (1) Structures of Al-NIL complexes and (2) Reactivity of Al-NIL complexes. Highlights of the research work include reversible redox chemistry that has been enabled by ligand design to shut down radical coupling pathways and to prevent loss of H2 from unsaturated ligand sites. These reversible redox properties have in turn enabled the characterization of Class III electron delocalization through Al when two NIL are bound to the Al(III) in different charge states. Characterization of the metalloaromatic character of square planar Al and Ga complexes has been achieved, and characterization of the delocalized electronic structures has provided a model within which to understand and predict the ET and PT chemistry of the NIL group 13 compounds. The capacity of Al-NIL complexes to perform ET and PT has been employed in reactions that use ET or PT reactivity only or in reactions where coupled ET/PT affords hydride transfer chemistry. As an example, ligand-based PT reactions initiate metal-ligand cooperative bond activation pathways for catalysis: this includes acceptorless dehydrogenation of formic acid and anilines and transfer hydrogenation chemistry. In a complementary approach, ligand based ET/PT chemistry has been used in the study of dihydropyridinate (DHP-) chemistry where it was shown that N-coordination of group 13 ions lowers kinetic barriers to DHP- formation. Taken together, the discussion presented herein illustrates that the NIL chemistry of Al(III), and also of Ga(III) and In(III) holds promise for further developments in catalysis and energy storage.

Improving the Performance of Pd for Formic Acid Dehydrogenation by Introducing Barium Titanate.

Formic acid, a safe and widely available organic compound, produces hydrogen under mild conditions, with the existence of Pd-based catalysts. Efficiently generating hydrogen via formic acid decomposition (FAD) is restricted by the cleavage of the C-H bond in adsorbed HCOO* and strong adsorption of hydrogen on the Pd surface. Herein, tetragonal-phase barium titanate (TBT) was in situ grown on reduced graphene oxide (rGO) to support Pd (Pd/TBT/rGO) for FAD. The internal electric field exists around TBT owing to its spontaneous polarization capacity. The physical characterizations illustrate that the introduction of barium titanate affects the catalytic performance of the catalyst by decreasing the particle size of Pd nanoparticles (NPs) and forming electron-rich Pd. The as-synthesized Pd/TBT/rGO exhibited excellent catalytic activity and hydrogen selectivity for FAD with a high initial turnover frequency up to 3019.72 h-1 at 333 K. The reason for this enhancement is not only the small-size Pd NPs but also the internal electric field from TBT, which promotes the desorption of adsorbed hydrogen on the Pd surface. Additionally, the electron-rich Pd is favorable to the cleavage of the C-H bond in HCOO*. This work will improve the understanding of the characterization of barium titanate and provide a new design strategy for the FAD catalyst.

Synthesis of Cr(OH)3/ZrO2@Co-based metal-organic framework from waste poly(ethylene terephthalate) for hydrogen production via formic acid dehydrogenation at low temperature

Recycling waste polyethylene terephthalate (PET) bottles into value-added ligand materials for synthesizing metal-organic frameworks derived catalysts is an eco-friendly and economically viable process. The waste PET bottles were readily broken down into 1,4-benzenedicarboxylic acid (BDC) ligands in a highly alkaline environment. Herein, we fabricated a Co@Cr(OH)3/ZrO2 catalyst via the carbonization of PET-derived UiO-66 metal-organic frameworks for the catalytic dehydrogenation of formic acid at low temperatures. The as-prepared Co@Cr(OH)3/ZrO2 NP catalyst provides a turnover frequency (TOF) of 7685 h-1 for hydrogen generation (120 mL in 1.5 min) at ambient temperature. This is due to the uniform dispersion of the fine metal NPs (Co NPs, ∼3.75 nm) and the synergistic effect of the Co NPs and Cr(OH)3/ZrO2 supports. In addition, the characterization results indicate that porous Zr-MOFs may effectively enclose extremely small particles, which is favorable for enhanced dehydrogenation performance. In addition, the Co@Cr(OH)3/ZrO2 catalysts demonstrated excellent stability against aggregation and were recyclable over seven cycles without any significant catalytic loss. Thus, this study provides a sustainable methodology for the development of MOF-derived, effective, and stable catalysts for formic acid (FA) dehydrogenation towards hydrogen production.

Unveiling the formic acid dehydrogenation dynamics steered by Strength-Controllable internal electric field from barium titanate

Formic acid is a desirable liquid hydrogen storage compound for solving transport and storage problems of hydrogen for onboard fuel cells. Optimizing adsorption/desorption energy of intermediates can directly modulate the performance of Pd catalysts in formic acid dehydrogenation (FAD). Herein, we introduce internal electric field with controllable strength to regulate the adsorption/desorption of intermediates on Pd. Non-ferroelectric cubic-phase barium titanate (CBT) is heat-treated at high temperature to obtain ferroelectric tetragonal-phase barium titanate (TBT(C)), which exhibits internal electric field. The strength of the internal electric field is successfully adjusted by heat treatment at different temperatures. The size of Pd nanoparticles is restricted between 2.2 and 2.7 nm, and the electronic effect of Pd is effectively eliminated by coating TBT(C) with mesoporous carbon shell (TBT(C)@SC). Experimental results prove that the internal electric field promotes the desorption of hydrogen on Pd. Pd/TBT(C)@SC-800 obtained by heat treatment at 800 °C, with the optimal internal electric field strength, exhibits high activity and hydrogen selectivity for FAD. This work provides a new strategy for designing FAD catalysts.

Efficient Atomically Dispersed Co/N-C Catalysts for Formic Acid Dehydrogenation and Transfer Hydrodeoxygenation of Vanillin.

Atomically dispersed catalysts have gained considerable attention due to their unique properties and high efficiency in various catalytic reactions. Herein, a series of Co/N-doped carbon (N-C) catalysts was prepared using a metal-lignin coordination strategy and employed in formic acid dehydrogenation (FAD) and hydrodeoxygenation (HDO) of vanillin. The atomically dispersed Co/N-C catalysts showed outstanding activity, acid resistance, and long-term stability in FAD. The improved activity and stability may be attributed to the high dispersion of Co species, increased surface area, and strong Co-N interactions. XPS and XAS characterization revealed the formation of Co-N3 centers, which are assumed to be the active sites. In addition, DFT calculations demonstrated that the adsorption of formic acid on single-atom Co was stronger than that on Co13 clusters, which may explain the high catalytic activity. The Co/N-C catalyst also showed promising performance in the transfer HDO of vanillin with formic acid, without any external additional molecular H2.

Mechanistic Insights of the Ir‐bipyridonate Catalyzed Aqueous Methanol Dehydrogenation and Transfer Dehydrogenation to Acetophenone: Experimental and DFT Study

AbstractThe mechanisms of the Cp*IrIII(bpyOO)‐catalyzed (bpyOO=bidentate (NN) doubly deprotonated 2,2′‐bipyridine‐6,6′‐diol) acceptorless methanol dehydrogenation and acetophenone transfer hydrogenation by methanol under basic conditions have been explored by the combination of 1H NMR, kinetics, and DFT computational studies. During dehydrogenation of methanol and of its dehydrogenated derivatives, the presence of two iridium hydride species (anionic [Cp*Ir(bpyOO)H]−, C* and neutral [Cp*Ir(bpyOOH)H], D*), which interconvert depending on pH, was detected. The DFT studies on a Cp model system highlighted three interrelated catalytic cycles of methanol, formaldehyde and formic acid dehydrogenation, all leading to the same hydride intermediates C and D. The dehydrogenation of methanol prefers a direct β‐hydride transfer pathway from the methoxide ion to Ir, rather than the classical β‐hydride elimination pathway from a coordinated methoxide ligand, but an alternative bifunctional H+/H− transfer with involvement of a ligand O atom may become competitive at lower pH. The transfer hydrogenation of acetophenone using methanol as hydrogen source features species C* as resting state, with the acetophenone reduction being rate‐determining and following the reverse pathway of methanol oxidation, with a first‐order acetophenone decay and a kinetic isotope effect of 2.36±0.09.

A Palladium Catalyst Supported on Boron-Doped Porous Carbon for Efficient Dehydrogenation of Formic Acid.

Formic acid has emerged as a highly promising hydrogen storage material, and the development of efficient catalysts to facilitate its dehydrogenation remains imperative. In this study, a novel catalyst consisting of palladium nanoparticles supported on boron-doped porous carbon (Pd/BPC) was successfully synthesized to enable efficient hydrogen production through the dehydrogenation of formic acid. The impacts of the boron doping ratio, doping temperature, and palladium reduction temperature on the catalyst's performance were systemically investigated. The results demonstrated the Pd/BPC catalyst synthesized with a carbon-to-boron ratio of 1:5 by calcination at 900 °C and subsequent reduction at 60 °C exhibited superior formic acid dehydrogenation performance, being 2.9 and 3.8 times greater than that of the Pd/PC catalysts without boron doping and commercial Pd/C, respectively. Additionally, the catalyst showed excellent cycle stability with no significant activity reduction after five consecutive cycles. Experimental and theoretical results reveal that boron doping not only facilitates the homogenous distribution of Pd nanoparticles but also induces a stronger support-metal interaction, thereby reinforcing the catalytic performance. This research is expected to provide valuable insights into the economically viable and efficient production of environmentally friendly hydrogen energy.

Potential-Rate Correlations of Supported Palladium-Based Catalysts for Aqueous Formic Acid Dehydrogenation.

Aqueous formic acid dehydrogenation (FAD) is a crucial process for hydrogen production, as hydrogen is a clean energy carrier. During this process, formic acid converts into hydrogen and carbon dioxide over a catalyst. Pd-based catalysts have exhibited significant potential in FAD due to their high activity and selectivity. In this study, we investigated aqueous thermal FAD in a mixture of formic acid and sodium formate using electrochemical open-circuit potential (OCP) measurement by loading the catalysts onto a conductive substrate as a working electrode. By varying the reaction conditions such as the concentration of reactants and modifying Pd with Ag, different FAD rates were obtained. Consequently, we revealed the correlation between the catalyst OCP and FAD rate; superior FAD rates reflected a more negative catalyst OCP. Furthermore, deactivation was observed across all catalysts during FAD, with a concurrent increase in catalyst OCP. Interestingly, we found that the logarithm of the FAD rate showed a linear correlation with the OCP of the catalyst during the decay phase, which we quantitatively explained based on the reaction mechanism. This study presents a new discovery that bridges thermal and electrocatalysis.

Exploring the Effects Behind the Outstanding Catalytic Performance of PdAg Catalysts Supported on Almond Shell‐Derived Activated Carbon Towards the Dehydrogenation of Formic Acid

In this work, highly efficient carbon‐supported Pd‐based catalysts for formic acid dehydrogenation were synthesized by a straightforward wet impregnation‐reduction method. The carbon support was obtained from a biomass residue (almond shell) prepared via H3PO4‐assisted hydrothermal carbonization (HTC) and thermal activation. This carbon support was doped with nitrogen groups to study the effect on the electronic properties and catalytic performance of the catalysts. Investigating the formation of PdAg alloys with varying Pd:Ag molar ratios resulted in catalysts exhibiting enhanced catalytic activity compared to monometallic Pd counterparts. Notably, the Pd1Ag0.5/NAS catalyst displayed outstanding catalytic performance, achieving an initial TOF of 1716 h‐1 (calculated in the first 3 minutes of reaction and expressed per mole of Pd) and maintaining substantial activity over 6 consecutive reaction cycles. This work elucidates the successful synthesis of effective catalysts, emphasizing the influence of nitrogen doping and PdAg alloy composition on catalytic behavior and stability.

Boosting the catalytic activity of Pd-nanocatalysts by anchoring transition metal atoms on carbon supports for formic acid dehydrogenation

Liquid formic acid (FA) dehydrogenation, which needs high-performance catalysts to generate green hydrogen at room temperature, is a promising chemical hydrogen storage technology that can replace fossil fuels in energy-related devices. In this work, a novel nanocatalyst with ultrafine palladium nanoparticles (Pd NPs) immobilized on a transition metal atom-decorated carbon support was synthesized for the dehydrogenation of liquid FA. Via a hydrothermal of glucose and carbonitride with a following Co doping through a heat treatment process, porous carbons with evenly dispersed Co-sites on it were strategically achieved, which could be used as a support for immobilizing Pd NPs. The obtained Pd/NC-Co1% catalyst exhibited much superior catalytic activities to those samples without Co doping on the support (Pd/NC and PdCo1%/NC), showing an impressive turnover frequency of 3045 h−1 at 50 °C for FA dehydrogenation. Other transition metal species such as Fe- and Ni-decorated carbon nanocatalysts also showed an improved catalytic activity for FA dehydrogenation. This work not only provides an efficient method to synthesize nanocatalysts with ultrafine metal NPs but also demonstrates that highly dispersed metal atoms on the support can effectively affect the immobilized NPs, resulting in an enhancement of catalytic performance.

Unravelling the reaction mechanism for H2 production via formic acid decomposition over Pd: Coverage-Dependent microkinetic modeling

As a key liquid organic hydrogen carrier, investigating the decomposition of formic acid (HCOOH) on the Pd (111) transition metal surface is imperative for harnessing hydrogen energy. Despite a multitude of studies, the major mechanisms and key intermediates involved in the dehydrogenation process of formic acid remain a great topic of debate due to ambiguous adsorbate interactions. In this research, we develop an advanced microkinetic model based on first-principles calculations, accounting for adsorbate–adsorbate interactions. Our study unveils a comprehensive mechanism for the Pd (111) surface, highlighting the significance of coverage effects in formic acid dehydrogenation. Our findings unequivocally demonstrate that H coverage on the Pd (111) surface renders formic acid more susceptible to decompose into H2 and CO2 through COOH intermediates. Consistent with experimental results, the selectivity of H2 in the decomposition of formic acid on the Pd (111) surface approaches 100 %. Considering the influence of H coverage, our kinetic analysis aligns perfectly with experimental values at a temperature of 373 K.

Bimetallic PdAg clusters loaded on hierarchical self-pillared pentasil zeolite as efficient catalysts for formic acid dehydrogenation

In the present study, siliceous self-pillared pentasil (SPP) zeolite with regular mesopores was synthesized and used as a support for anchoring bimetallic PdAg clusters through a facile impregnation-reduction method. The as-prepared PdAg/SPP catalysts with different Pd/Ag ratios were demonstrated to catalyze formic acid dehydrogenation for hydrogen production. XRD results confirmed the formation of PdAg alloy on the surface of SPP zeolite. The Pd7Ag3/SPP catalyst showed high activity at 80 °C with an initial turn-over frequency (TOF) of 1263.6 h−1, proving the strategy using hierarchical SPP zeolite as carrier is advantageous over bulky zeolites for making highly active formic acid dehydrogenation catalysts.

Carbon-supported Metal Nanoparticle Catalysts for Dehydrogenation of Formic Acid and Hydrodeoxygenation of Polyols

Carbon-supported Metal Nanoparticle Catalysts for Dehydrogenation of Formic Acid and Hydrodeoxygenation of Polyols

Plasmon-Switched Kinetics for Formic Acid Dehydrogenation: Selective Adsorption Driven by Local Field and Hot Carriers.

Understanding illumination-mediated kinetics is essential for catalyst design in plasmon catalysis. Here we prepare Pd-based plasmonic catalysts with tunable electronic structures to reveal the underlying illumination-enhanced kinetic mechanisms for formic acid (HCOOH) dehydrogenation. We demonstrate a kinetic switch from a competitive Langmuir-Hinshelwood adsorption mode in dark to a non-competitive type under irradiation triggered by local field and hot carriers. Specifically, the electromagnetic field induces a spatial-temporal separation of dehydrogenation-favorable configurations of reactant molecule HCOOH and HCOO- due to their natural different polarities. Meanwhile, the generated energetic carriers can serve as active sites for selective molecular adsorption. The hot electrons act as adsorption sites for HCOOH, while holes prefer to adsorb HCOO- . Such unique non-competitive adsorption kinetics induced by plasmon effects serves as another typical characteristic of plasmonic catalysis that remarkably differs from thermocatalysis. This work unravels unique adsorption transformations and a kinetic switching driven by plasmon nonthermal effects.

Ultrafine PdCo nanoparticles on amine-functionalized CeZrSBA-15 with short channels for efficient H2 production from formic acid dehydrogenation

The rational design of heterogeneous catalysts with remarkable activity and low cost is essential yet challenging for formic acid (HCOOH, FA) dehydrogenation. Herein, ultrafine bimetallic PdCo nanoparticles (NPs) dispersed on the amine-functionalized CeZrSBA-15 (CeZrSBA-15-NH2) with short channels have been successfully prepared. The optimized catalyst Pd3Co2/CeZrSBA-15-NH2 (the Pd/Co molar ratio is 3:2) displayed the extraordinary catalytic performance of FA dehydrogenation with 100 % FA conversion and H2 selectivity. Furthermore, in the presence of sodium formate (SF) as an additive, the catalytic system achieved an impressive initial turnover frequency (TOF) of 2001 h−1 at a temperature of 323 K, which is better than the TM (transition metal)-containing Pd-based heterogeneous systems ever published under the similar reaction conditions. The exceptional catalytic activity is ascribed to several key factors, including the presence of short channels that facilitate the efficient transfer of reactants, the ultrafine size (1.6 nm) and uniform dispersion of PdCo nanoparticles, which serve as the active catalytic sites on the CeZrSBA-15-NH2 support. Additionally, the regulated electronic effects induced by Pd and Co, coupled with the metal-support interaction (MSI) effect, further enhance the catalytic performance. This work affords a new paradigm into developing effective mesoporous silica-based heterogeneous catalysts for H2 production from FA dehydrogenation.

Pd Nanoparticles Supported on Carbon Nanotubes with Carbonyl-Driven Pd0–Pdδ+ Interface Formation for the Catalytic Dehydrogenation of Formic Acid

Pd Nanoparticles Supported on Carbon Nanotubes with Carbonyl-Driven Pd⁰–Pd^δ+ Interface Formation for the Catalytic Dehydrogenation of Formic Acid

Exceptional activity of amino-modified rGO-immobilized PdAu nanoclusters for visible light-promoted dehydrogenation of formic acid

Formic acid (FA), which is obtainable through CO2 hydrogenation with green hydrogen or biomass conversion, has been used as a prospective liquid organic hydrogen carrier (LOHC) because of the abundant advantages of renewability, wide availability, stability, and high volumetric capacity (53 g H2/L). The development of highly efficient catalytic systems to achieve enhanced catalytic activity is attractive but still challenging. Herein, ultrafine and highly dispersed PdAu nanoclusters (NCs) anchored on amino-modified reduced graphene oxide (ArGO) were successfully synthesized via a facile impregnation-reduction method and applied as a catalyst toward formic acid dehydrogenation (FAD). Benefiting from the promoting effect of amino groups, the strain and ligand effect in the alloy, and the Mott-Schottky effect between PdAu NCs and ArGO, the resultant PdAu/ArGO affords an ultrahigh activity under visible light irradiation with an exceptional turnover frequency value of 10699.5 h−1 at 298 K without any additives, more than 2.6 times improvement than that under dark, which is the highest among all reported catalysts under the same conditions. This study provides a green and convenient strategy for developing more efficient and sustainable FAD catalysts and promotes the effective utilization of FA as a prospective renewable LOHC.