A5005194597- Zeolite Catalysis and Synthesis
- Advanced NMR Techniques and Applications
- Chemical Synthesis and Characterization
- Catalysis and Oxidation Reactions
- Catalytic Processes in Materials Science
- Metal-Organic Frameworks: Synthesis and Applications
- Catalysis and Hydrodesulfurization Studies
- Mesoporous Materials and Catalysis
- Polyoxometalates: Synthesis and Applications
- Advanced Chemical Physics Studies
- Magnetism in coordination complexes
- Catalysis for Biomass Conversion
- Ga2O3 and related materials
- Analytical Chemistry and Chromatography
- Inorganic and Organometallic Chemistry
- Catalysts for Methane Reforming
- Advancements in Battery Materials
- Biodiesel Production and Applications
- Extraction and Separation Processes
- Nanocluster Synthesis and Applications
- Petroleum Processing and Analysis
- Ammonia Synthesis and Nitrogen Reduction
- Pigment Synthesis and Properties
- Electron and X-Ray Spectroscopy Techniques
- Advanced Data Processing Techniques
Boreskov Institute of Catalysis
2013-2024
Russian Academy of Sciences
2007-2012
Understanding methane activation pathways on Zn-modified high-silica zeolites (ZSM-5, BEA) is of particular importance because the possibility involvement in coaromatization with higher alkanes this type zeolites. Herein, two samples zeolite BEA containing exclusively either small zinc oxide clusters or isolated Zn2+ cations have been synthesized and thoroughly characterized by a range spectroscopic methods (1H MAS NMR, DRIFTS, XPS, EXAFS, HRTEM) to show that only one Zn-species, ZnO...
With regard to a general interest in methane utilization rational way the activation and transformation of on Ag-modified zeolite ZSM-5 (Ag/H-ZSM-5) have been studied with solid-state NMR. The occurs by dissociation C–H bond silver cations via "carbenium" pathway: cleavage results methoxy groups (O–CH3) possibly silver-hydride species (Ag–H). formation surface Ag/H-ZSM-5 has detected experimentally 13C CP/MAS NMR at 508–623 K for first time. A comparative analysis kinetics H/D exchange...
By using 13C solid-state NMR spectroscopy and GC-MS analysis, the activation of methane coaromatization propane have been monitored on gallium-modified zeolite BEA at 573−823 K. A noticeable degree involvement 13C-label from methane-13C into aromatic reaction products (benzene, toluene) has demonstrated. The major intermediate represents gallium-methyl species, which are formed by dissociative adsorption Ga2O3 species zeolite. minor activation, Ga-methoxy groups, provide aromatics...
Methane activation pathways as well methane involvement in the reaction of ethylene aromatization on In-modified H-ZSM-5 zeolite (In/H-ZSM-5) have been studied with solid-state NMR spectroscopy. The state indium In/H-ZSM-5 dependence procedure, reductive or oxidative, has analyzed X-ray photoelectron spectroscopy (XPS). On basis 1H MAS analysis evolution quantity Brønsted acid sites (BAS) and XPS it inferred that exists form either In+ InO+ isolated cationic species zeolite. interaction...
With regard to establishing the effect of nature Zn species loaded in a zeolite on aromatization propane, transformation 13C-labeled propane (propane-1-13C and propane-2-13C) has been monitored by 1H 13C (CP) MAS NMR at 296–623 K for two samples, containing exclusively either isolated Zn2+ cations (Zn2+/H-BEA sample) or small (ZnO)n clusters zinc oxide (ZnO/H-BEA sample). It established that similar intermediates, π-complex propene σ-allylzinc species, are formed aromatics both samples....
The analysis of n-but-1-ene transformation on Zn-modified zeolite H-BEA, containing zinc exclusively in the form either Zn2+ cations (Zn2+/H-BEA sample) or small clusters ZnO (ZnO/H-BEA sample), has been performed with 13C solid-state nuclear magnetic resonance (NMR) at 296–673 K. number intermediates, including π-complex n-but-2-ene, methylallylzinc, and delocalized carbanionic species formed by interaction oligomeric polyenes Zn sites, have identified for both samples. Methyl-substituted...
The effect of Zn2+ cations and small clusters ZnO on isobutene transformation to aromatic hydrocarbons Zn-modified zeolites (Zn2+/H-ZSM-5 ZnO/H-BEA) has been investigated with 13C MAS NMR FTIR spectroscopic techniques. It is inferred that mainly stabilized in the form a π-complex Zn2+/H-ZSM-5 zeolite at 296–573 K, whereas oligomerization olefin Brønsted acid sites (BAS) ZnO/H-BEA occurs 296 K. Using isobutene, selectively labeled isotope either ═CH2 or ═C< groups, for analysis evolution...
Silver-modified zeolites exhibit high selectivity for alkene transformation to aromatic hydrocarbons. To inquire into the effect of silver cations in zeolite on pathways propene aromatization, transformations H-ZSM-5 and Ag/H-ZSM-5 have been investigated by 13C MAS NMR Fourier-transform infrared spectroscopy. It is established that at 296–773 K occurs Brønsted acid sites (BAS) mechanism conjunct polymerization, as evidenced detection cyclopentenyl cation intermediates. On contrary, forms...
Kinetics of H/D hydrogen exchange between C1–n-C4 alkanes and Brønsted acid sites (BAS) both the pure acid-form zeolite BEA (H-BEA) Ga-modified (Ga/H-BEA) was monitored by 1H MAS NMR spectroscopy in situ at 423–563 K. Comparative analysis rates for H-BEA Ga/H-BEA zeolites reveals a remarkable increase rate 1–2 orders magnitude, decrease activation energy, an appearance regioselectivity into methyl groups C3-n-C4 upon modification with gallium. These data identify evident promoting effect Ga...
The peculiar role of either Zn2+ cations or small ZnO clusters located inside the zeolite pores in propylene transformation to aromatic hydrocarbons on Zn2+/H-ZSM-5 and ZnO/H-BEA zeolites has been analyzed. 13C MAS NMR FTIR spectroscopic investigation revealed similar properties different Zn-sites with respect oligomerization. Both species are capable convert higher C6–C9 olefins which represent precursors simple benzene-based aromatics. mechanism such oligomerization inferred include...
The interaction of olefins with metal oxides affords surface species which are considered to be the intermediates in olefin isomerization reactions. nature and structure these after earlier characterization by IR spectroscopy still remain debatable. In this paper using 13C solid-state NMR we have characterized formed from propene, n-butene, isobutene on γ-Al2O3 α-Ga2O3, based analysis specific chemical shifts expected for similar organometallic or oxygenated compounds. clearly shows that...
Abstract Coordinatively unsaturated metal sites (CUS) play an important role in catalysis by metal‐organic frameworks (MOF). Being intrinsic part of the framework CUS take acidic active industrially relevant processes such as condensation or oxidation reactions. The key step reactions represents coordination reagents to CUS. In MOFs mechanism reagent interaction with is poorly understood. Herein, we characterize a widely used acidity probe pyridine MIL‐100(Al) MOF means 2 H solid‐state NMR...
The signal of Zn in a tetrahedral environment was detected by 67 MAS NMR spectroscopy for the activated ZnO/H-ZSM-5 zeolite and that an octahedral hydrated 2+ /ZSM-5 zeolites.
Es gehören zwei dazu: Ein hoher Konversionsgrad für den Einbau der 13C-Atome von Methan in die Produkte einer Methan/Propan-Coaromatisierung am Zeolith Zn/H-BEA wurde durch 13C-Festkörper-NMR-Spektroskopie und GC-MS nachgewiesen. Isotopenmarkierungsexperimente zum Mechanismus ergaben, dass zunächst aus Propan gebildete aromatische Spezies methyliert werden, worauf eine Ringexpansion/-kontraktion folgt (siehe Schema).
In-modified zeolites possess promising catalytic properties for light alkane dehydrogenation and aromatization. However, the role of different indium species, which are present in zeolite pores after activation, remains unknown. Here, transformation propane on BEA containing either In+ or InO+ species has been monitored with 13C MAS NMR at 298–773 K. It is inferred that In+/H-BEA sites inactive conversion T < 723 The InO+/H-BEA occurs by two parallel routes: followed formed alkene...