A5013665296- Catalytic Processes in Materials Science
- Zeolite Catalysis and Synthesis
- Catalysis and Oxidation Reactions
- Catalysts for Methane Reforming
- Carbon Dioxide Capture Technologies
- Metal-Organic Frameworks: Synthesis and Applications
- Advanced Chemical Physics Studies
- Chemical Synthesis and Characterization
- Ga2O3 and related materials
- Mesoporous Materials and Catalysis
- Advanced NMR Techniques and Applications
- Luminescence Properties of Advanced Materials
- Ammonia Synthesis and Nitrogen Reduction
- Solid-state spectroscopy and crystallography
- Spectroscopy and Laser Applications
- Methane Hydrates and Related Phenomena
- Layered Double Hydroxides Synthesis and Applications
- Transition Metal Oxide Nanomaterials
- Electrocatalysts for Energy Conversion
- Catalysis and Hydrodesulfurization Studies
- Surface Chemistry and Catalysis
- Quantum, superfluid, helium dynamics
- Inorganic Fluorides and Related Compounds
- Advanced Materials Characterization Techniques
- Advanced materials and composites
N.D. Zelinsky Institute of Organic Chemistry
2011-2024
University of South Carolina
2006-2010
Russian Academy of Sciences
2000-2004
Three γ/β-Ga2O3 nanoparticle catalysts that differ in the relative ratio of γ-Ga2O3 to β-Ga2O3 were prepared evaluate effect H2 treatment (500 °C, 2 h) on coordination environment bulk and surface Ga sites, Lewis acidity catalytic activity propane dehydrogenation (PDH). Independent treatment, initial PDH increases with fraction phase. This is explained by presence weak acid sites (LAS) while such are absent γ-Ga2O3. Treatment all three but for different reasons. For higher fractions β-Ga2O3,...
The formation and nature of surface indium species in zirconia-supported catalysts for the hydrogenation CO2 to methanol has been investigated by infrared (IR) spectroscopy. We studied dissociation hydrogen on In2O3/m-ZrO2, In2O3/t-ZrO2, In2O3/am-ZrO2 m-ZrO2:In (m-, t- am- refers monoclinic, tetragonal amorphous, respectively is a solid solution material), with without redox pretreatment. Indium hydride hydroxyl groups form at room temperature all redox-treated upon their exposure hydrogen....
The influence of the phase ZrO2 support (monoclinic, tetragonal, and amorphous, referred to as m-, t-, am-, respectively) on nature surface species involved in methanol synthesis rates their formation ZrO2-supported, In-based catalysts for CO2 hydrogenation has been investigated. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) at 300 °C 20 bar (H2:CO2:N2 = 3:1:1 volume ratio) m-ZrO2:In, In2O3/t-ZrO2, In2O3/am-ZrO2 (m-ZrO2:In is a solid solution) shows that...
Comparison of DRIFT spectra OH groups in MFI with framework Si/Al ratios equal to 25 or 40 the same zeolites after reaction zinc vapour at 773 K indicated quantitative substitution acidic hydroxyls by Zn2+ ions. Complete protons indicates that high some cations are localized isolated aluminium occupied oxygen tetrahedra single negative charges. This results formation sites only partially compensated excessive positive charges bivalent cations. In parallel, amount negatively charged remains...
The copper-modified ZSM-5 zeolites, prepared by ion-exchange in an aqueous solution of Cu(CH3COO)2 and subjected to different treatments were studied FTIR spectroscopy using molecular hydrogen adsorbed at 77 K room temperature as a probe. For reduced calcined CuZSM-5 samples broad range IR spectra measured discussed detail. At least two Cu+ sites with CO distinguished It was established that the copper adsorption which strongly perturb molecules are ions also adsorb dinitrogen molecules....
Ni−ZSM-5 zeolite reduced in CO was characterized by DRIFTS measurements of adsorbed CO, N2, and H2 molecules EPR spectroscopy. The results indicate that N2 on Ni+ ions are strongly perturbed, resulting large bathochromic shifts their vibration frequencies. sites stable up to moderately high temperatures (550−600 K). At higher temperatures, the converted Ni0 Ni2+ according following disproportionation reaction: 2Ni+ → + Ni0.
The formation and nature of surface indium species in the alumina-supported oxide (In2O3/Al2O3) catalytic material has been investigated by means UV–vis spectroscopy IR adsorbed probe molecules CO H2. It found for first time that high-temperature reduction hydrogen results substitution protons hydroxyl groups alumina support (In+) cations form low-dimensional cationic clusters/associates. Oxidation In+ leads to oxo-species. These oxo-species have be active heterolytic dissociation hydrogen,...
This work explores how H2 pretreatment at 550 °C induces structural transformation of two gallia-based propane dehydrogenation (PDH) catalysts, viz. nanocrystalline γ/β-Ga2O3 and amorphous Ga2O3 (GaO x ) supported on silica (γ-Ga2O3/SiO2 Ga/SiO2, respectively) it affects their activity, propene selectivity stability with time stream (TOS). Ga/SiO2-H2 shows poor activity selectivity, no coking deactivation TOS, similar to Ga/SiO2. In contrast, the high initial γ-Ga2O3/SiO2-H2 decline TOS but...
Dehydration of Zn2+ exchanged NaY zeolite was studied by means DRIFT spectra adsorbed dihydrogen and carbon monoxide as molecular probes. Unlike alkaline earth forms faujasites dehydration ZnY at moderately high temperatures results in the formation bridging protons nanometric ZnO or mixed hydroxylated microclusters instead hydroxy groups MeOH+ cations. After subsequent above 573 K zinc oxide clusters interact with acidic resulting ions localized SII sites. These sites adsorb hydrogen its...
Parallel spectral measurements allow comparison of intensities the 1H MAS-NMR peaks from bridging and silanol hydroxyl groups for same samples HMOR, HY HZSM-5 zeolites pretreated in vacuum at 400 °C with those corresponding DRIFT bands. The results obtained indicate that IR extinction coefficients acidic are several times higher than less groups. This can be explained by polarization ability former, resulting stretching OH bonds upon vibrational excitation. It is suggested O–H vibrations...
The results of a DRIFT study carbon monoxide molecular adsorption and hydrogen dissociative on gallium-modified mordenite MFI (ZSM-5) zeolites are presented. It was found that in the reduced (Ga-MOR) both Ga(3+) Ga(+) exchanged cations present can be detected by CO adsorption. Ga-MOR dissociatively adsorb at elevated temperatures, resulting formation gallium hydride species acidic hydroxyl groups. In Ga-MFI evacuated 823 K under medium vacuum conditions only intrazeolite were detected....