Activity For Dehydrogenation Of Formic Acid Research Articles

Computational study on graphdiyne supported PdxCuy clusters as potential catalysts for formic acid dehydrogenation

Designing low-cost and efficient catalysts for formic acid dehydrogenation (FAD) is crucial to facilitate the practical applications of formic acid as a hydrogen carrier. Using density functional theory calculations, we designed nine graphdiyne-supported Pd/Cu single-, double-, and triple-atom catalysts, investigating their stability and formic acid dehydrogenation performance. The results indicate that as the number of active metal sites increases, the catalytic activity for formic acid dehydrogenation improves, i.e., M3@GDY > M2@GDY > M1@GDY (M = Pd/Cu). Moreover, a synergistic effect between Pd and Cu atoms is observed in PdxCu3-x@GDY, where the activity sequence of triple-atom catalysts was Pd1Cu2@GDY > Pd2Cu1@GDY > Pd3@GDY > Cu3@GDY. Particularly, Pd1Cu2@GDY exhibits superior FAD catalytic activity and hydrogen selectivity, presenting a potential novel formic acid dehydrogenation catalyst. Electronic structure analysis indicates that the band center difference Δε (Δε = εd - εp) serves as an assessment descriptor for formic acid dehydrogenation activity. Microkinetic analysis further confirms the performance of TACs predicted by DFT results, and shows that all TACs have good H2 selectivity even at a high temperature.

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.

Iridium Catalyst Immobilized on Crosslinked Polyethyleneimine for Continuous Hydrogen Production Using Formic Acid.

Hydrogen is an alternative fuel that can play a critical role in achieving net zero emissions, leading to global environment sustainability. An iridium-immobilized catalyst based on polyethyleneimine (PEI) was synthesized and utilized for hydrogen production via formic acid dehydrogenation (FADH). Iridium complex is cross-linked with its ligand and PEI to form the immobilized catalyst, where the iridium content could be easily varied in the range of 1-10 %. The structure of the iridium-immobilized catalyst was confirmed using solid-state NMR, DNP NMR, and FTIR spectroscopies. The iridium-immobilized catalyst with PEI showed excellent catalytic activity for FADH, exhibiting the catalyst's highest turnover frequency (TOF) value of 73 200 h-1 and a large turnover number (TON) value of over 1 130 000. The catalyst could be used for continuous hydrogen production via FADH, exhibiting high durability for over 2 000 h with TON value of 332 889 without any degradation in catalytic activity. The obtained hydrogen gas was evaluated for power generation using a standard fuel cell, as well as achieved 5 h of stable power generation.

Efficient formic acid dehydrogenation on AuPd/N-TiO2: The role of N dopant and the effect of TiO2 crystalline phase

Nitrogen-doped TiO2 (N-TiO2) was prepared by direct pyrolysis of the amino-functionalized titanium metal–organic framework NH2-MIL-125(Ti) in air, and highly dispersed AuPd nanoparticles were anchored on N-TiO2. The synthesized catalysts showed excellent activity for formic acid dehydrogenation. At 60 °C, the total turnover frequency value of Au2Pd8/N-TiO2-catalyzed dehydrogenation reaction was 7725 h−1, which was 2.9 times that of the N-free catalyst (Au2Pd8/TiO2) under the same conditions. The excellent performance of the Au2Pd8/N-TiO2 catalyst was attributed to the high content of anatase TiO2, the synergistic effect between the N-TiO2 support and the metal nanoparticles, the alloying effect between Au and Pd and the small size of the metal particles. The presence of N can enhance the interaction between AuPd and the support, effectively prevent the aggregation of AuPd on the surface of the support, and improve the catalytic activity and reusability of the catalyst. The effect of TiO2 crystalline phase (anatase and rutile) and N doping on the performance of Au2Pd8/N-TiO2-catalyzed formic acid decomposition was analyzed by means of theoretical calculations. The results showed that the anatase and N-TiO2-based catalysts could reduce the barrier for formic acid dehydrogenation. This work combined experiments with theoretical calculations to provide a new approach to the modification of formic acid dehydrogenation catalysts.

Second Sphere Effects Promote Formic Acid Dehydrogenation by a Single‐Atom Gold Catalyst Supported on Amino‐Substituted Graphdiyne

AbstractRegulating the second sphere of homogeneous molecular catalysts is a common and effective method to boost their catalytic activities, while the second sphere effects have rarely been investigated for heterogeneous single‐atom catalysts primarily due to the synthetic challenge for installing functional groups in their second spheres. Benefiting from the well‐defined and readily tailorable structure of graphdiyne (GDY), an Au single‐atom catalyst on amino‐substituted GDY is constructed, where the amino group is located in the second sphere of the Au center. The Au atoms on amino‐decorated GDY displayed superior activity for formic acid dehydrogenation compared with those on unfunctionalized GDY. The experimental studies, particularly the proton inventory studies, and theoretical calculations revealed that the amino groups adjacent to an Au atom could serve as proton relays and thus facilitate the protonation of an intermediate Au−H to generate H2. Our study paves the way to precisely constructing the functional second sphere on single‐atom catalysts.

Second Sphere Effects Promote Formic Acid Dehydrogenation by a Single-Atom Gold Catalyst Supported on Amino-Substituted Graphdiyne.

Regulating the second sphere of homogeneous molecular catalysts is a common and effective method to boost their catalytic activities, while the second sphere effects have rarely been investigated for heterogeneous single-atom catalysts primarily due to the synthetic challenge for installing functional groups in their second spheres. Benefiting from the well-defined and readily tailorable structure of graphdiyne (GDY), an Au single-atom catalyst on amino-substituted GDY is constructed, where the amino group is located in the second sphere of the Au center. The Au atoms on amino-decorated GDY displayed superior activity for formic acid dehydrogenation compared with those on unfunctionalized GDY. The experimental studies, particularly the proton inventory studies, and theoretical calculations revealed that the amino groups adjacent to an Au atom could serve as proton relays and thus facilitate the protonation of an intermediate Au-H to generate H2. Our study paves the way to precisely constructing the functional second sphere on single-atom catalysts.

Air-mediated construction of O, N-rich carbon: An efficient support of palladium nanoparticles toward catalytic formic acid dehydrogenation and 4-nitrophenol reduction

Oxygen and nitrogen-rich functional groups which are generally present in carbon materials may significantly affect their catalytic properties. The development of O, N-rich functional carbon materials with a simplified and low-budget strategy is of great importance for practical application. Herein, we describe a facile and straightforward method to prepare high contents of nitrogen and oxygen-rich carbon derived from ethylenediamine tetra-acetic acid tetra-sodium salt (Na4EDTA) by one-step carbonization in muffle furnace without inert gas protection. Compared with the carbon (EC-N700) synthesized in an argon atmosphere, the carbon (EC-A700) synthesized in an air-rich condition was more conducive to the formation of edge defects and topological defects and possessed higher contents of N and O elements. Consequently, the O, N-rich carbon EC-A700 was used as an efficient support of palladium nanoparticles toward catalytic formic acid dehydrogenation and nitroarene reduction. The catalyst Pd/EC-A700 achieved outstanding activity for formic acid dehydrogenation with a turnover frequency (TOF) up to 7039 h−1 at 60 °C. At the same time, the obtained catalyst Pd/EC-A700 also demonstrated exceptional catalytic performance in the 4-nitrophenol (4-NP) reduction with corresponding rate constant k of 0.72 min−1 under mild reaction conditions, which proved that the prepared catalyst Pd/EC-A700 has potentially applied in catalytic hydrogenation. This low-cost and simple approach breaks the tradition in mind that pyrolysis should always operate under inert conditions and provides a straightforward route to construct O, N-rich carbon as appealing materials for a wide variety of applications.

Crafting Porous Carbon for Immobilizing Pd Nanoparticles with Enhanced Catalytic Activity for Formic Acid Dehydrogenation

AbstractThe development of highly active heterogeneous catalytic systems that catalyze formic acid (FA) to generate CO‐free H2 holds great promise for future energy demands, but is often limited by the low catalytic activity and stability of metal catalysts under ambient conditions. It is thus highly desirable to rationally design a catalyst to boost the catalytic performance. Herein, a general room‐temperature HNO3‐treatment approach (RTHTA) is developed to accomplish surface modification of various porous carbon materials for immobilizing ultrafine palladium nanoparticles (Pd NPs). A significantly enhanced catalytic performance of the immobilized Pd NPs toward the selective dehydrogenation of FA is achieved, which gives a record‐high turnover frequency of 13333 h−1 at 60 °C, corresponding to a calculated H2 generation rate of 50.8 L H2 min−1 gPd−1. The results presented here may provide insight into the formation and stabilization of highly active immobilized metal nanoparticles, as well as the enhanced catalytic performance of Pd NPs for catalytic dehydrogenation reactions.

Remarkable enhancement of PdAg/rGO catalyst activity for formic acid dehydrogenation by facile boron-doping through NaBH4 reduction

A novel boron-doped PdAg alloy anchored on reduced graphene oxide (rGO) was synthesized via a facile aqueous chemical reduction method using NaBH4 as the reducing agent. The characterization results confirm the formation of ultrafine PdAgB alloy nanoparticles that are uniformly dispersed on the surface of rGO. The as-prepared PdAgB/rGO catalysts show composition-dependent catalytic activity for the hydrogen generation from formic acid/sodium formate aqueous solution, with Pd0.90Ag0.10B/rGO exhibiting the highest activity at 298 K. Compared to Pd0.90Ag0.10/rGO prepared by using N2H4·H2O as the reductant, Pd0.90Ag0.10B/rGO displays higher activity towards dehydrogenation of formic acid irrespective of its relatively larger particle size, suggesting the significant promotion of B to the catalytic performance. The superior performance of Pd0.90Ag0.10B/rGO could be attributed to the combination of engineered alloy nanostructure and electronic modification effect of boron species.

Fabrication of a Spherical Superstructure of Carbon Nanorods.

Hierarchical superstructures in nano/microsize have attracted great attention owing to their wide potential applications. Herein, a self-templated strategy is presented for the synthesis of a spherical superstructure of carbon nanorods (SS-CNR) in micrometers through the morphology-preserved thermal transformation of a spherical superstructure of metal-organic framework nanorods (SS-MOFNR). The self-ordered SS-MOFNR with a chestnut-shell-like superstructure composed of 1D MOF nanorods on the shell is synthesized by a hydrothermal transformation process from crystalline MOF nanoparticles. After carbonization in argon, the hierarchical SS-MOFNR transforms into SS-CNR, which preserves the original chestnut-shell-like superstructure with 1D porous carbon nanorods on the shell. Taking the advantage of this functional superstructure, SS-CNR immobilized with ultrafine palladium (Pd) nanoparticles (Pd@SS-CNR) exhibits excellent catalytic activity for formic acid dehydrogenation. This synthetic strategy provides a facile method to synthesize uniform spherical superstructures constructed from 1D MOF nanorods or carbon nanorods for applications in catalysis and energy storage.

Dehydrogenation of Formic Acid Catalyzed by Water‐Soluble Ruthenium Complexes: X‐ray Crystal Structure of a Diruthenium Complex

Dehydrogenation of formic acid over various Ru‐arene complexes containing N‐donor chelating ligands was investigated in H2O and isolated and characterized several important catalytic intermediate species to elucidate the reaction pathway for formic acid dehydrogenation. Among the studied complexes, Ru‐arene complexes, namely [(η6‐C6H6)Ru(κ2‐NpyNH2‐AmQ)Cl]+ (C‐2), [(η6‐C10H14)Ru(κ2‐NpyNH2‐AmQ)Cl]+ (C‐3) and [(η6‐C6H6)Ru(κ2‐NpyNHMe‐MAmQ)Cl]+ (C‐4) [AmQ = 8‐aminoquinoline and MAmQ = 8‐(N‐methylamino)quinoline] were proved to be the efficient catalysts for formic acid dehydrogenation at 90 °C, even in the absence of base. With an initial TOF of 940 h–1, complex C‐4 displayed the highest catalytic activity for formic acid dehydrogenation in H2O and it can be recycled up to 5 times with a TON of 2248. Effect of temperature, pH, formic acid and catalyst concentration on the reaction kinetics were also investigated in detail. Extensive mechanistic investigations using mass spectrometry and NMR evidenced the formation of a coordinatively unsaturated species [(η6‐C6H6)Ru(κ2‐NpyNH‐AmQ)]+ (C‐2A)/[(η6‐C6H6)Ru(κ2‐NpyNMe‐MAmQ)]+ (C‐4A) as the active component during the catalytic dehydrogenation of formic acid. We further characterized the dimer‐form of C‐2A, possibly the catalyst resting state, by single‐crystal X‐ray crystallography.

The Formation, Structure and Activity for Formic Acid Dehydrogenation of Evaporated Pd—Au Alloy Films

Article The Formation, Structure and Activity for Formic Acid Dehydrogenation of Evaporated Pd—Au Alloy Films was published on October 1, 1969 in the journal Zeitschrift für Physikalische Chemie (volume 67, issue 4_6).