Reversible Grafting in Surface Organometallic Chemistry with a Late Transition‐Metal Amidinate Precursor DOI Creative Commons
Christian Ehinger, Christophe Copéret

Helvetica Chimica Acta, Journal Year: 2024, Volume and Issue: unknown

Published: Oct. 17, 2024

Abstract Supported catalysts are central to industrial catalytic processes. While traditional synthesis methods often yield poorly defined materials, thus complicating structural elucidation, Surface Organometallic Chemistry (SOMC) offers a solution, producing well‐defined structures. Recent advances in SOMC precursor development have shown that amidinate‐based complexes privileged class of precursors generate supported metallic nanoparticles. In context, this study investigates the grafting mechanism prototypical amidinate precursor, Ir(COD)(DIA) ( 1‐Ir ), onto SiO 2 . Unique complexes, is occur without ligand release, creating reversible covalent bond. Using tris( tert ‐butoxy)silanol as molecular analogue for silanol group on , structure grafted species elucidated by single X‐Ray diffraction, comparison IR spectroscopy, and absorption spectroscopy (XAS) data. The reversibility reaction with O−H groups demonstrated using variable‐temperature NMR DFT calculations. Notably, we show partial degrafting also possible at elevated temperatures under vacuum.

Language: Английский

Reactivity Switch of Platinum with Gallium: From Reverse Water Gas Shift to Methanol Synthesis DOI
Wei Zhou, Enzo Brack, Christian Ehinger

et al.

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(15), P. 10806 - 10811

Published: April 4, 2024

The development of efficient catalysts for the hydrogenation CO

Language: Английский

Citations

6
Decoding the Promotional Effect of Iron in Bimetallic Pt–Fe-nanoparticles on the Low Temperature Reverse Water–Gas Shift Reaction DOI
Colin Hansen, Wei Zhou, Enzo Brack

et al.

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: unknown

Published: Sept. 30, 2024

The reverse water-gas shift (RWGS) reaction is a key technology of the chemical industry, central to emerging circular carbon economy. Pt-based catalysts have previously been shown effectively promote RWGS, especially when modified by promoter elements. However, their active states are still poorly understood. Here, we show that intimate incorporation an iron into metal-oxide-supported nanoparticles can increase activity and selectivity for low temperature (LT-RWGS) substantially drastically outperform unpromoted materials. Specifically, study explores promotional effect in Pt-Fe bimetallic systems supported on silica (Pt

Language: Английский

Citations

3
Alloyed molybdenum enables efficient alcohol hydrodeoxygenation with supported bimetallic catalysts DOI Creative Commons
Christian Ehinger, Stephan Pollitt, Jordan De Jesus Silva

et al.

Chemical Science, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

Bimetallic heterogeneous catalysts combining group 9 metals (Rh, Ir) or 10 (Ni, Pd, Pt) with Mo on a silica-based support have been synthesized via surface organometallic chemistry and assessed in their catalytic activity for the hydrodeoxygenation (HDO) of alcohols particular emphasis structural evolution role Mo. The investigation was conducted an air-free approach to isolate any sample alterations exclusively those caused by reaction. Structural analysis performed using combination (S)TEM, IR, XAS. It found that Ir-Mo/SiO2, Rh-Mo/SiO2, Pt-Mo/SiO2 display high primary, secondary, tertiary alcohol deoxygenation, while Pd-Mo/SiO2 selectively catalyses deoxygenation. Other combinations as well corresponding monometallic materials do not same activity. X-ray absorption spectroscopy confirmed metallic states M (M = Ni, Rh, Ir, Pt), K-edge XANES showed varying amounts Mo(0), Mo(iv) Mo(vi) depending metal counterpart fresh materials, indicated complete conversion lower oxidation (IV 0) during For Pt, alloy formation (M-Mo) identified M-Mo paths EXAFS supported CO-IR spectroscopy. In contrast where some Mo(0) is present at nanoparticle surface, Pd-Mo forms but likely retains core, suggested CO-chemisorption. Reactivity studies suggest primarily undergo dehydration-hydrogenation, evidenced olefin MoO x /SiO2, Ir/SiO2 Ir-Mo/SiO2 under inert conditions. contrast, primary secondary follow different mechanism, correlated presence species highlighting C-O bond activation. These findings provide new insights into structure-activity relationships Mo-based bimetallic catalysts, underscoring influence strong substrate dependence mechanistic pathways.

Language: Английский

Citations

0
Unsymmetrical amidinate complexes of cobalt and manganese: Synthesis, structure and catalytic properties DOI

Xinhua Hu,

Hongbo Tong, Meisu Zhou

et al.

Polyhedron, Journal Year: 2025, Volume and Issue: unknown, P. 117562 - 117562

Published: April 1, 2025

Language: Английский

Citations

0
Implications of Ga promotion and metal–oxide interface from tailored PtGa propane dehydrogenation catalysts supported on carbon DOI Creative Commons
Enzo Brack, Milivoj Plodinec, Marc‐Georg Willinger

et al.

Chemical Science, Journal Year: 2023, Volume and Issue: 14(44), P. 12739 - 12746

Published: Jan. 1, 2023

Propane Dehydrogenation is a key technology, where Pt-based catalysts have widely been investigated in industry and academia, with development exploring the use of promoters (Sn, Zn, Ga, etc.) additives (Na, K, Ca, Si, towards improved catalytic performances. Recent studies focused on role Ga promotion: while computations suggest that plays enhancing selectivity stability PtGa through Pt-site isolation as well morphological changes, experimental evidence are lacking because oxide supports prevent more detailed investigation. Here, we develop methodology to generate Pt nanoparticles tailored interfaces carbon by combining surface organometallic chemistry (SOMC) specific thermolytic molecular precursors containing or not siloxide ligands. This approach enables preparation supported nanoparticles, exhibiting an interface, suitable for state-of-the art electron microscopy XANES characterization. We show introduction formation homogenously alloyed, amorphous sharp contrast highly crystalline monometallic nanoparticles. Furthermore, presence interface shown stabilize small particles, at expense propene loss (formation cracking side-products, methane/ethene), explaining such Na, K Ca industrial catalysts.

Language: Английский

Citations

9
Reactivity Switch of Platinum with Gallium: from Reverse Water Gas Shift to Methanol Synthesis DOI Creative Commons
Wei Zhou, Enzo Brack, Christian Ehinger

et al.

Published: Jan. 24, 2024

The development of efficient catalysts for the hydrogenation CO2 to methanol using “green” H2 is foreseen be a key step close carbon cycle. In this study, we show that small and narrowly distributed alloyed PtGa nanoparticles supported on silica, prepared via surface organometallic chemistry (SOMC) approach, display notable activity methanol, reaching 7.2 mol h-1 molPt-1 formation rate with 54% intrinsic CH3OH selectivity. This reactivity sharply contrasts what expected Pt, which favors reverse water gas shift reaction, albeit poor (2.6 molPt-1). situ XAS studies indicate ca. 50% Ga reduced Ga0 yielding nanoparticles, while remaining persist as isolated GaIII sites. catalyst slightly dealloys under conditions displays redox dynamics PtGa-GaOx interfaces, responsible promoting both Further tailoring interface by support in place silica enables improve factor ~5.

Language: Английский

Citations

2
Unveiling the Potential of Redox Chemistry to Form Size-Tunable, High-Index Silicon Particles DOI Creative Commons
Megan A. Parker,

Safa Khaddad,

Nicolas Farès

et al.

Chemistry of Materials, Journal Year: 2024, Volume and Issue: 36(22), P. 10986 - 10993

Published: Aug. 28, 2024

Silicon particles of intermediate sizes (75–200 nm) scatter visible wavelengths, making them promising candidates for optical devices. The solution synthesis silicon in this size range, however, has proved challenging chemists over the past few decades. Here, a solution-phase provides pathway toward reaching tunability between 45 and 230 nm via changing reactant ratio reaction Zintl phase (Na4Si4) with an amidinate-stabilized Si(IV) coordination complex. Coherent domain sizes, determined from powder X-ray diffraction, show that crystallite are uniform across all particle perhaps indicating aggregation mechanism growth. amidinate ligands act to stabilize surface. Combined surface techniques (ToF-SIMS, FTIR, photoelectron spectroscopy) confirm presence ligands, as well primary amine passive oxidation layer on particles. refractive index is measured individual using holographic microscopy, displaying nearly 4.1 at wavelength 532 nm. Thus, these should light intensely manipulation.

Language: Английский

Citations

1
Reactivity Switch of Platinum with Gallium: From Reverse Water Gas Shift to Methanol Synthesis DOI Creative Commons
Wei Zhou, Enzo Brack, Christian Ehinger

et al.

Published: March 28, 2024

The development of efficient catalysts for the hydrogenation CO2 to methanol using “green” H2 is foreseen be a key step close carbon cycle. In this study, we show that small and narrowly distributed alloyed PtGa nanoparticles supported on silica, prepared via surface organometallic chemistry (SOMC) approach, display notable activity methanol, reaching 7.2 mol h-1 molPt-1 formation rate with 54% intrinsic CH3OH selectivity. This reactivity sharply contrasts what expected Pt, which favors reverse water gas shift reaction, albeit poor (2.6 molPt-1). situ XAS studies indicate ca. 50% Ga reduced Ga0 yielding nanoparticles, while remaining persist as isolated GaIII sites. catalyst slightly dealloys under conditions displays redox dynamics PtGa-GaOx interfaces, responsible promoting both Further tailoring interface by support in place silica enables improve factor ~5.

Language: Английский

Citations

1
Impact of Alloying and Metal-Oxide Interface on PtGa Propane Dehydrogenation Catalysis from Tailored Catalysts on Carbon DOI Creative Commons
Enzo Brack, Milivoj Plodinec, Marc‐Georg Willinger

et al.

Published: Aug. 7, 2023

Propane Dehydrogenation is a key technology, where Pt-based catalysts have been widely investigated, with development focusing on optimising promoters (Sn, Ga, etc.) towards improved catalytic performances. Recent studies focused Ga promotional effect: while Pt-site isolation by has proposed to play role in enhancing stability and selectivity, other effects, such as morphological changes well the of supports additives, remain poorly understood. Here, we develop methodology generate (bi)metallic – Pt PtGa nanoparticles tailored interfaces combining surface organometallic chemistry carbon specific thermolytic molecular precursors, containing or not Si. This approach enables detailed characterization via electron microscopy X-ray absorption spectroscopy, shows that introduction yields amorphous nanoparticles, display higher performances, than corresponding highly crystalline suggested earlier computational studies. Furthermore, this study also presence an oxide interface increases catalyst activity, at expense selectivity (formation cracking side-products, methane/ethene), hence, use additives Na/K/Ca industrial catalysts.

Language: Английский

Citations

1
Reversible Grafting in Surface Organometallic Chemistry with a Late Transition‐Metal Amidinate Precursor DOI Creative Commons
Christian Ehinger, Christophe Copéret

Helvetica Chimica Acta, Journal Year: 2024, Volume and Issue: unknown

Published: Oct. 17, 2024

Abstract Supported catalysts are central to industrial catalytic processes. While traditional synthesis methods often yield poorly defined materials, thus complicating structural elucidation, Surface Organometallic Chemistry (SOMC) offers a solution, producing well‐defined structures. Recent advances in SOMC precursor development have shown that amidinate‐based complexes privileged class of precursors generate supported metallic nanoparticles. In context, this study investigates the grafting mechanism prototypical amidinate precursor, Ir(COD)(DIA) ( 1‐Ir ), onto SiO 2 . Unique complexes, is occur without ligand release, creating reversible covalent bond. Using tris( tert ‐butoxy)silanol as molecular analogue for silanol group on , structure grafted species elucidated by single X‐Ray diffraction, comparison IR spectroscopy, and absorption spectroscopy (XAS) data. The reversibility reaction with O−H groups demonstrated using variable‐temperature NMR DFT calculations. Notably, we show partial degrafting also possible at elevated temperatures under vacuum.

Language: Английский

Citations

0