Gina Noh

Last Name

Noh

First Name

Gina

ORCID

0000-0003-4717-5767

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Publications 1 - 9 of 9

The Influence of ZnO-ZrO2 Interface in Hydrogenation of CO2 to CH3OH
Šot, Petr; Noh, Gina; Weber, Ines; et al. (2022)
Helvetica Chimica Acta
The influence of the interface in ZnO-ZrO2 catalysts for the selective hydrogenation of CO2 to CH3OH is investigated. Specifically, we perturbed its structure using two different synthetic methods: surface organometallic chemistry (SOMC) and flame-spray pyrolysis (FSP) and investigated the speciation of the resulting materials by spectroscopic techniques, such as XAS, NMR, IR, UV-Vis, and EPR. The results indicate that oxidic Zn particles that co-exist with ZrO2, as synthesized by FSP, show a superior selectivity in contrast to Zn(0) nanoparticles or Zn(II) single sites on ZrO2, formed using SOMC. Further experiments underlined the importance of the ZnO-ZrO2 interface in the process: only materials with such an interface exhibit highly selective production of CH3OH, proceeding likely via the formation of the surface CH3O intermediates.
Selective Hydrogenation of CO2 to CH3OH on Supported Cu Nanoparticles Promoted by Isolated TiIV Surface Sites on SiO2
Noh, Gina; Lam, Erwin; Alfke, Jan L.; et al. (2019)
ChemSusChem
Small and narrowly distributed Cu nanoparticles, supported on SiO2 decorated with isolated TiIV sites, prepared via surface organometallic chemistry, show significantly improved CO2 hydrogenation activity and CH3OH selectivity compared to the corresponding Cu nanoparticles supported on SiO2. We propose that these isolated Lewis acid TiIV sites, evidenced by UV-Vis spectroscopy, stabilize surface intermediates at the interface between Cu nanoparticles and the support.
Silica-Supported PdGa Nanoparticles: Metal Synergy for Highly Active and Selective CO2-to-CH3OH Hydrogenation
Docherty, Scott; Phongprueksathat, Nat; Lam, Erwin; et al. (2021)
JACS Au
The direct conversion of CO2 to CH3OH represents an appealing strategy for the mitigation of anthropogenic CO2 emissions. Here, we report that small, narrowly distributed alloyed PdGa nanoparticles, prepared via surface organometallic chemistry from silica-supported GaIII isolated sites, selectively catalyze the hydrogenation of CO2 to CH3OH. At 230 °C and 25 bar, high activity (22.3 molMeOH molPd–1 h–1) and selectivity for CH3OH/DME (81%) are observed, while the corresponding silica-supported Pd nanoparticles show low activity and selectivity. X-ray absorption spectroscopy (XAS), IR, NMR, and scanning transmission electron microscopy–energy-dispersive X-ray provide evidence for alloying in the as-synthesized material. In situ XAS reveals that there is a dynamic dealloying/realloying process, through Ga redox, while operando diffuse reflectance infrared Fourier transform spectroscopy demonstrates that, while both methoxy and formate species are observed in reaction conditions, the relative concentrations are inversely proportional, as the chemical potential of the gas phase is modulated. High CH3OH selectivities, across a broad range of conversions, are observed, showing that CO formation is suppressed for this catalyst, in contrast to reported Pd catalysts.
CO2 Hydrogenation to CH3OH on Supported Cu Nanoparticles: Nature and Role of Ti in Bulk Oxides vs Isolated Surface Sites
Noh, Gina; Docherty, Scott; Lam, Erwin; et al. (2019)
The Journal of Physical Chemistry C
CO2 hydrogenation on Cu-catalysts generated from ZnII single-sites: Enhanced CH3OH selectivity compared to Cu/ZnO/Al2O3
Lam, Erwin; Noh, Gina; Larmier, Kim; et al. (2021)
Journal of Catalysis
The hydrogenation of CO2 to CH3OH is mostly performed by a catalyst consisting mainly of copper and zinc (Cu/ZnO/Al2O3). Here, Cu-Zn based catalysts are generated using surface organometallic chemistry (SOMC) starting from a material consisting of isolated ZnII surface sites dispersed on SiO2 – ZnII@SiO2. Grafting of [Cu(OtBu)]4 on the surface silanols available on ZnII@SiO2 followed by reduction at 500 °C under H2 generates CuZnx alloy nanoparticles with remaining ZnII sites according to X-ray absorption spectroscopy (XAS). This Cu-Zn/SiO2 material displays high catalytic activity and methanol selectivity, in particular at higher conversion compared to benchmark Cu/ZnO/Al2O3 and most other catalysts. In situ XAS shows that CuZnx alloy is partially converted into Cu(0) and Zn(II) under reaction conditions, while ex situ solid state nuclear magnetic resonance and infrared spectroscopic studies only indicate the presence of methoxy species and no formate intermediates are detected, in contrast to most Cu-based catalysts. The absence of formate species is consistent with the higher methanol selectivity as recently found for the related Cu-Ga/SiO2.
Correction to “Silica-Supported PdGa Nanoparticles: Metal Synergy for Highly Active and Selective CO2‑to-CH3OH Hydrogenation”
Docherty, Scott R.; Phongprueksathat, Nat; Lam, Erwin; et al. (2022)
JACS Au
Methane-to-Methanol on Mononuclear Copper(II) Sites Supported on Al2O3: Structure of Active Sites from Electron Paramagnetic Resonance
Meyet, Jordan; Ashuiev, Anton; Noh, Gina; et al. (2021)
Angewandte Chemie. International Edition
The selective conversion of methane to methanol remains one of the holy grails of chemistry, where Cu-exchanged zeolites have been shown promote this reaction under stepwise conditions. Over the years, several active sites have been proposed, ranging from mono-, di- to trimeric CuII. Herein, we report the formation of well-dispersed monomeric CuII species supported on alumina using surface organometallic chemistry and their reactivity towards the selective and stepwise conversion of methane to methanol. Extensive studies using various transition alumina supports combined with spectroscopic characterization, in particular electron paramagnetic resonance (EPR), show that the active sites are associated with specific facets, which are typically found in γ- and η-alumina phase, and that their EPR signature can be attributed to species having a tri-coordinated [(Al2O)CuIIO(OH)]− T-shape geometry. Overall, the selective conversion of methane to methanol, a two-electron process, involves two monomeric CuII sites that play in concert.
Enhanced CH3OH Selectivity in CO2 Hydrogenation using Cu-based Catalysts Generated via SOMC from GaIII Single-Sites
Lam, Erwin; Noh, Gina; Chan, Ka Wing; et al. (2020)
Chemical Science
CO2 Hydrogenation on Cu/Al2O3: Role of Metal/Support Interface in Driving Activity and Selectivity of a Bifunctional Catalyst
Lam, Erwin; Corral‐Pérez, Juan J.; Larmier, Kim; et al. (2019)
Angewandte Chemie. International Edition

Publications 1 - 9 of 9

Gina Noh

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