Nature of active palladium sites on nitrogen doped carbon nanofibers in selective hydrogenation of acetylene

Чесноков, В. В.; Кривенцов, В. В.; Malykhin, S. E.; Svintsitskiy, Dmitry A.; Podyacheva, O. Yu.; Lisitsyn, A.S.; Richards, Ryan M.

doi:10.1016/j.diamond.2018.08.007

Cited by 21 publications

(17 citation statements)

References 62 publications

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“…The presence of chlorine atoms was not found in the samples. Single Au atoms as well as single Pt-group metals atoms are known to be present in a cationic state and not in a metallic state on different supports [9,32,34,35,38,[43][44][45][46]. Single Au atoms observed by HAADF/STEM ( Figures 1 and 2) either present in a small concentration, or present initially in a cationic state but can be photo-reduced during the XPS measurements [44].…”

Section: Xps Studymentioning

confidence: 99%

“…Recently, we demonstrated that N-doping of carbon supports for Pd [32][33][34], Pt [35], Ru [35,36], and Cu [37] catalysts significantly promoted the gas-phase formic acid decomposition. The promotion was assigned to improving the metal dispersion for Cu [37] and appearance of novel active sites-single metal atoms of Pt-group metals stabilized by N-species of the support [32][33][34][35]38]. Liquid-phase formic acid decomposition over some Pd/C catalysts was also reported to be improved by N-doping of the carbon support [25,26,39,40].…”

Section: Introductionmentioning

confidence: 98%

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Hydrogen Production from Formic Acid over Au Catalysts Supported on Carbon: Comparison with Au Catalysts Supported on SiO2 and Al2O3

et al. 2019

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Characteristics and catalytic activity in hydrogen production from formic acid of Au catalysts supported on porous N-free (Au/C) and N-doped carbon (Au/N-C) have been compared with those of Au/SiO2 and Au/Al2O3 catalysts. Among the catalysts examined, the Au/N-C catalyst showed the highest Au mass-based catalytic activity. The following trend was found at 448 K: Au/N-C > Au/SiO2 > Au/Al2O3, Au/C. The trend for the selectivity in hydrogen production was different: Au/C (99.5%) > Au/Al2O3 (98.0%) > Au/N-C (96.3%) > Au/SiO2 (83.0%). According to XPS data the Au was present in metallic state in all catalysts after the reaction. TEM analysis revealed that the use of the N-C support allowed obtaining highly dispersed Au nanoparticles with a mean size of about 2 nm, which was close to those for the Au catalysts on the oxide supports. However, it was by a factor of 5 smaller than that for the Au/C catalyst. The difference in dispersion could explain the difference in the catalytic activity for the carbon-based catalysts. Additionally, the high activity of the Au/N-C catalyst could be related to the presence of pyridinic type nitrogen on the N-doped carbon surface, which activates the formic acid molecule forming pyridinium formate species further interacting with Au. This was confirmed by density functional theory (DFT) calculations. The results of this study may assist the development of novel Au catalysts for different catalytic reactions.

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Section: Xps Studymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Hydrogen Production from Formic Acid over Au Catalysts Supported on Carbon: Comparison with Au Catalysts Supported on SiO2 and Al2O3

et al. 2019

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“…It is formed due to oxidation of the metallic Pd surface by atmospheric oxygen. Alternatively, some Pd 2+ species may exist in atomically dispersed state strongly interacting with nitrogen, oxygen or carbon defects of the support [13][14][15]35,36]. This Pd could not be observed by the HRTEM equipment used in this work.…”

Section: Characterization Of the Pd Catalystsmentioning

confidence: 88%

“…The lowest value of the Pd3d 5 / 2 binding energy among the Sibunit-containing catalysts is observed for the Pd/C catalyst and corresponds to 335.8 eV. This Pd state is usually attributed to small metal particles interacting with the carbon support [13,35,37]. The Pd3d 5 / 2 lines for the Pd/Mel/C (muf) and Pd/Mel/C (MW) catalysts are strongly shifted to higher binding energies (336.4 and 336.3 eV, respectively) as compared to that for the Pd/C sample.…”

Section: Characterization Of the Pd Catalystsmentioning

confidence: 99%

Boosting Hydrogen Production from Formic Acid over Pd Catalysts by Deposition of N-Containing Precursors on the Carbon Support

et al. 2019

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Formic acid is a promising liquid organic hydrogen carrier (LOHC) since it has relatively high hydrogen content (4.4 wt%), low inflammability, low toxicity and can be obtained from biomass or from CO2. The aim of the present research was the creation of efficient 1 wt% Pd catalysts supported on mesoporous graphitic carbon (Sibunit) for the hydrogen production from gas-phase formic acid. For this purpose, the carbon support was modified by pyrolysis of deposited precursors containing pyridinic nitrogen such as melamine (Mel), 2,2′-bipyridine (Bpy) or 1,10-phenanthroline (Phen) at 673 K. The following activity trend of the catalysts Pd/Mel/C > Pd/C ~ Pd/Bpy/C > Pd/Phen/C was obtained. The activity of the Pd/Mel/C catalyst was by a factor of 4 higher than the activity of the Pd/C catalyst at about 373 K and the apparent activation energy was significantly lower than those for the other catalysts (32 vs. 42–46 kJ/mol). The high activity of the melamine-based samples was explained by a high dispersion of Pd nanoparticles (~2 nm, HRTEM) and their strong electron-deficient character (XPS) provided by interaction of Pd with pyridinic nitrogen species of the support. The presented results can be used for the development of supported Pd catalysts for hydrogen production from different liquid organic hydrogen carriers.

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“…In another context, highly dispersed Pd nanoparticles supported on carbon nanofibers [111] and nitrogen doped carbon nanofibers, Pd/NCNFs, [112] for the selective acetylene hydrogenation have been also investigated. Different metal contents were explored, however, single Pd atoms were formed at the surface when Pd concentration was below 0.2 wt.% or less, existing as two states with ratio strongly depending on the metal loading and, consequently conditioning the catalytic performance.…”

Section: Other Porous Carbonsmentioning

confidence: 99%

Carbon-Based Materials for the Development of Highly Dispersed Metal Catalysts: Towards Highly Performant Catalysts for Fine Chemical Synthesis

et al. 2020

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Single-atom catalysts (SACs), consisting of metals atomically dispersed on a support, are considered as advanced materials bridging homogeneous and heterogeneous catalysis, representing the catalysis at the limit. The enhanced performance of these catalysts is due to the combination of distinct factors such as well-defined active sites, comprising metal single atoms in different coordination environments also varying its valence state and strongly interacting with the support, in this case porous carbons, maximizing then the metal efficiency in comparison with other metal surfaces consisting of metal clusters and/or metal nanoparticles. The purpose of this review is to summarize the most recent advances in terms of both synthetic strategies of producing porous carbon-derived SACs but also its application to green synthesis of highly valuable compounds, an area in which the homogeneous catalysts are classically used. Porous carbon-derived SACs emerge as a type of new and eco-friendly catalysts with great potential. Different types of carbon forms, such as multi-wall carbon nanotubes (MWCNTs), graphene and graphitic carbon nitride or even others porous carbons derived from Metal–Organic-Frameworks (MOFs) are recognized. Although it represents an area of expansion, experimentally and theoretically, much more future efforts are needed to explore them in green fine chemical synthesis.

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Nature of active palladium sites on nitrogen doped carbon nanofibers in selective hydrogenation of acetylene

Cited by 21 publications

References 62 publications

Hydrogen Production from Formic Acid over Au Catalysts Supported on Carbon: Comparison with Au Catalysts Supported on SiO2 and Al2O3

Hydrogen Production from Formic Acid over Au Catalysts Supported on Carbon: Comparison with Au Catalysts Supported on SiO2 and Al2O3

Boosting Hydrogen Production from Formic Acid over Pd Catalysts by Deposition of N-Containing Precursors on the Carbon Support

Carbon-Based Materials for the Development of Highly Dispersed Metal Catalysts: Towards Highly Performant Catalysts for Fine Chemical Synthesis

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