A5017416587- Zeolite Catalysis and Synthesis
- Mesoporous Materials and Catalysis
- Metal-Organic Frameworks: Synthesis and Applications
- Chemical Synthesis and Characterization
- Catalytic Processes in Materials Science
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Catalysis and Oxidation Reactions
- Catalysis and Hydrodesulfurization Studies
- Advanced NMR Techniques and Applications
- Crystal Structures and Properties
- Covalent Organic Framework Applications
- Ammonia Synthesis and Nitrogen Reduction
- Carbon Dioxide Capture Technologies
- Catalysis for Biomass Conversion
- Nanomaterials for catalytic reactions
- Polyoxometalates: Synthesis and Applications
- Glass properties and applications
- Clay minerals and soil interactions
- Membrane Separation and Gas Transport
- Inorganic and Organometallic Chemistry
- Radioactive element chemistry and processing
- Synthesis and Properties of Aromatic Compounds
- Crystallography and molecular interactions
- Advanced ceramic materials synthesis
Pohang University of Science and Technology
2016-2025
Korea Post
2008-2020
Sogang University
1996-2010
University of St Andrews
2004-2009
Durham University
2009
Korea Research Institute of Chemical Technology
2003-2009
Korea Institute of Machinery and Materials
2006-2008
Chungbuk National University
2001-2007
University of Portsmouth
2004-2007
Chungnam National University
2007
Abstract Diesel engine technology is still the most effective solution to meet tighter CO 2 regulations in mobility and transport sector. In implementation of fuel‐efficient diesel engines, poor thermal durability lean nitrogen oxides (NO x ) aftertreatment systems remains as one major technical hurdle. Divalent copper ions when fully exchanged into high‐silica LTA zeolites are demonstrated exhibit excellent activity maintenance for NO reduction with NH 3 under vehicle simulated conditions...
A series of LTA zeolites with Si/Al = 8.3-∞ and a UFI zeolite 11 are synthesized using benzylimidazolium-based cations as organic structure-directing agents in fluoride media, if required, together the tetramethylammonium ion. Two 16 showed an enhanced operating temperature window excellent thermal durability for selective catalytic reduction NOx NH3, compared to Cu-SSZ-13 commercially being used automotive applications.
ConspectusZeolites and related crystalline microporous materials with cavities channels of molecular dimensions are major importance for applications ranging from ion-exchange to adsorption catalysis. Because their unique shape-selective properties closely the size, shape, dimensionality intracrystalline cavities, much interest has been devoted discovery novel zeolitic over last several decades. As a result, dramatic expansion in structural domain materials, as well compositional range,...
Low-temperature standard NH3-SCR over copper-exchanged zeolite catalysts occurs on NH3-solvated Cu-ion active sites in a quasi-homogeneous manner. As key kinetically relevant reaction steps, the intermediate CuII(NH3)4 ion hydrolyzes to CuII(OH)(NH3)3 gain redox activity. The also transfers between neighboring cages form highly reactive intermediates. Via operando electron paramagnetic resonance spectroscopy and SCR kinetic measurements density functional theory calculations, we demonstrate...
Incorporation of Al atoms in particular sites the ZSM-5 structure is governed by Si/Al ratio during synthesis, and their distribution over twelve types tetrahedral (T1–T12) crystallization occurs a nonrandom manner according to results 27Al MAS NMR measurements on series as-made zeolites with Si/Al=14–250. Further support for this conclusion was provided MQMAS spectra (see picture) simulated X-ray diffraction data. Supporting information article available WWW under...
The synthesis, crystal structure, characterization, and catalytic properties of the novel medium-pore zeolite TNU-9 (framework type TUN), one most crystallographically complex zeolites known to date, are described. was found crystallize under hydrothermal conditions at expense a lamellar precursor over very narrow range SiO2/Al2O3 NaOH/SiO2 ratios in presence 1,4-bis(N-methylpyrrolidinium)butane Na+ ions as structure-directing agents. A combination molecular modeling Rietveld refinement...
A solid understanding of the molecular-level mechanisms responsible for zeolite crystallization remains one most challenging issues in modern science. Here we investigated formation pathway high-silica LTA crystals simultaneous presence tetraethylammonium (TEA(+)), tetramethylammonium (TMA(+)), and Na(+) ions as structure-directing agents (SDAs) with goal better charge density mismatch synthesis approach, which was designed to foster cooperation between two or more different SDAs. Nucleation...
A wide variety of different linear, diquaternary alkylammonium ions have been used as supplementary crystallization structure-directing agents (SDAs) in the synthesis UZM-12, a high-silica version zeolite erionite, via charge density mismatch (CDM) approach. When tetraethylammonium is CDM SDA, UZM-12 was found to be critically dependent not only on type alkali metal cations added another SDA mixture, but also size groups ammonium ion employed and length its central polymethylene chain that...
The mechanisms of m-xylene isomerization and disproportionation over 13 medium-pore zeolites three large-pore ones are investigated. While H-TNU-10 H-ZSM-57 with intersecting 10- 8-ring channels were found to show considerably higher p/o ratios than H-ZSM-5, a commercial catalyst, the GC-MS results from used zeolite catalysts demonstrate intrazeolitic build-up tri- tetramethylated diphenylmethane species, whose existence during transformation any acidic catalyst has not been experimentally...
We have recently reported an increase in low-temperature NH3–SCR activity of the copper-exchanged (Cu/Al = 0.50), high-silica (Si/Al 23) LTA catalyst when it is hydrothermally aged at 1023–1173 K. Here we demonstrate that this unexpected phenomenon originates from migration Cu+ ions present inside sod cages Cu-LTA to vacant single 6-rings which accompanies their oxidation Cu2+ during (hydro)thermal aging. Hence, cages, are inaccessible almost all reactant species so as be regarded useless...
Framework deformation, driven by the cations in channels, determines CO<sub>2</sub> ad- and desorption behavior of zeolites. This allows to tune zeolite properties efficient temperature swing adsorption processes.
UCSB-6 (framework type SBS) and UCSB-10 (SBT), two three-dimensional phosphate-based molecular sieves with supercages accessible through 12-ring (circumscribed by 12 tetrahedral atoms) windows, are structurally similar to the hexagonal cubic polytypes of faujasite or zeolite Y, an industrially relevant catalyst, but cage structures substantially different. Nonetheless, their inherent thermal instability has precluded any catalytic application so far. By using multiple inorganic cation charge...
27Al magic-angle spinning (MAS) and triple quantum (3Q) MAS NMR spectroscopic techniques were used to characterise zeolite Beta samples with framework Si/Al ratios between 9 215, obtained by synthesis in fluoride medium. A carefully controlled stepwise calcination procedure was adopted obtain H-Beta. partial resolution of the T-sites observed spectra, increasing ratios. The relative intensity these peaks varied gradually, ratio showing that occupancy crystallographic changes ratio....
A high-silica zeolite (Si/Al = 7.1) with the STI framework topology, denoted TNU-10, has been synthesized in presence of 1,4-bis(N-methylpyrrolidinium)butane and Na(+) cations as structure-directing agents, its structure proton form refined against laboratory powder X-ray data space group Fmmm (a 13.533(1) A, b 17.925(2) c 17.651(2) A). The symmetry is supported by electron diffraction energy minimization studies. as-made TNU-10 are extensively characterized elemental thermal analyses,...