105 results match your criteria: "Center for Surface Chemistry and Catalysis[Affiliation]"

Correction for 'Performance of ferrite nanoparticles in inductive heating swing adsorption (IHSA): how tailoring material properties can circumvent the design limitations of a system' by Maxim De Belder , , 2024, , 4144-4149, https://doi.org/10.1039/d4mh00377b.

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The organic compound niacin or nicotinic acid, also known as vitamin B (VitB), is essential for human nutrition and metabolic regulation. However, in high doses, it can provoke side effects, such as hyperglycemia, liver damage, and flushing. Development of a controlled release system that slowly releases VitB into the organism would avoid high dosing peaks, thus contributing to decrease the occurrence of side effects in nutritional supplementation.

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Inductive heating swing adsorption (IHSA) using hybrid adsorbents incorporating a porous material and ferrite nanoparticles holds promise to be a performant, electrified alternative for conventional gas separation. Successful implementation of hybrid adsorbents in IHSA depends on achieving a maximal specific absorption rate (SAR) in the conditions and at the frequency of the induction setup. This paper outlines and demonstrates successful strategies for optimization of the particle composition, tailoring the coercivity and susceptibility of the ferrite particles to optimal performance in a given alternating magnetic field.

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Eu doped ZnAl layered double hydroxides as calibrationless, fluorescent sensors for carbonate.

Chem Commun (Camb)

November 2023

Instituto de Física da Universidade de São Paulo, 05508-090 - São Paulo, SP, Brazil.

The photoluminescence properties (PL) of Eu hosted in the hydroxide layers of layered double hydroxides (LDHs) enables calibrationless quantification of anions in the interlayers. The concept is demonstrated during the nitrate-to-carbonate ion exchange in Zn/Al/Eu LDHs and can be implemented as a remote optical sensor to detect intrusion of anions such as Cl or CO.

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ConspectusSince the discovery of synthetic zeolites in the 1940s and their implementation in major industrial processes involving adsorption, catalytic conversion, and ion exchange, material scientists have targeted the rational design of zeolites: controlling synthesis to crystallize zeolites with predetermined properties. Decades later, the fundamentals of zeolite synthesis remain largely obscured in a black box, rendering rational design elusive. A major prerequisite to rational zeolite design is to fully understand, and control, the elementary processes governing zeolite nucleation, growth, and stability.

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CoFeO inverse opals with tunable catalytic activity for high-performance overall water splitting.

Nanoscale

June 2023

Quantum Solid-State Physics (QSP), Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200 D, 3001 Leuven, Belgium.

The development of earth-abundant and high-performance bifunctional catalysts for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) in alkaline electrolytes is required to efficiently produce hydrogen by electrochemical water splitting, but remains a challenge. We have fabricated mesoporous cobalt iron oxide inverse opals (m-CFO IO) with different mole ratios of cobalt and iron by a wet chemical method using polystyrene beads as a hard template, followed by calcination in air. The performance of the m-CFO IO as OER and HER electrocatalysts was investigated.

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A guideline for zeolite phase selection in inorganic synthesis media is proposed, based on a systematic exploration of synthesis from inorganic media using liquid Na, K, and Cs aluminosilicate. Although the Si/Al ratio of the zeolites is a continuous function of the synthesis conditions, boundaries between topologies are sharp. The here-derived phase selection criterion relates the obtained zeolite topology to the Si/Al ratio imposed by the synthesis medium.

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Porous silica is used as a drug delivery agent to improve the bioavailability of sparsely soluble compounds. In this approach, the active pharmaceutical ingredient (API) is commonly loaded into the porous silica by incipient wetness impregnation using organic solvents. Subsequent solvent elimination is critical as the residual solvent concentration cannot exceed threshold values set by health and safety regulations (e.

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Water plays a central role in the crystallization of a variety of organic, inorganic, biological, and hybrid materials. This is also true for zeolites and zeolite-like materials, an important class of industrial catalysts and adsorbents. Water is always present during their hydrothermal synthesis, either with or without organic species as structure-directing agents.

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Current nucleation models propose manifold options for the formation of crystalline materials. Exploring and distinguishing between different crystallization pathways on the molecular level however remain a challenge, especially for complex porous materials. These usually consist of large unit cells with an ordered framework and pore components and often nucleate in complex, multiphasic synthesis media, restricting in-depth characterization.

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Using hydrated silicate ionic liquids, phase selection and framework silicon-to-aluminum ratio during inorganic zeolite synthesis were studied as a function of batch composition. Consisting of homogeneous single phasic liquids, this synthesis concept allows careful control of crystallization parameters and evaluation of yield and sample homogeneity. Ternary phase diagrams were constructed for syntheses at 90 °C for 1 week.

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A reproducible synthesis strategy for ultracrystalline K,Na-aluminosilicate JBW zeolite is reported. The synthesis uses a Na-based hydrated silicate ionic liquid (HSIL) as a silicon source and gibbsite as the aluminum source. Al and Na NMR spectra exhibit crystalline second-order quadrupole patterns in the hydrated as well as dehydrated states and distinct resonances for different T-sites demonstrating an exceptional degree of order of the elements of the JBW framework, observed for the first time in a zeolite.

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An important aspect within zeolite synthesis is to make fully tunable framework materials with controlled aluminium distribution. A major challenge in characterising these zeolites at operating conditions is the presence of water. In this work, we investigate the effect of hydration on the Al NMR parameters of the ultracrystalline K,Na-compensated aluminosilicate JBW zeolite using experimental and computational techniques.

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LEV type zeolites were synthesized with four different structure-directing agents and converted to copper loaded NH-SCR catalysts. The synthesis recipe was found to impact the respective Al population in the two topologically different framework sites in double and single 6-rings, resolvable by Al MAS NMR spectroscopy. Hydrothermal stability was found to be related to the silanol concentration, Si/Al ratio, particle size, crystal morphology, crystal defects, external surface area, and microporosity.

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Industrial ammonia production without CO emission and with low energy consumption is one of the technological grand challenges of this age. Current Haber-Bosch ammonia mass production processes work with a thermally activated iron catalyst needing high pressure. The need for large volumes of hydrogen gas and the continuous operation mode render electrification of Haber-Bosch plants difficult to achieve.

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Storing methane in clathrates is one of the most promising alternatives for transporting natural gas (NG) as it offers similar gas densities to liquefied and compressed NG while offering lower safety risks. However, the practical use of clathrates is limited given the extremely low temperatures and high pressures necessary to form these structures. Therefore, it has been suggested to confine clathrates in nanoporous materials, as this can facilitate clathrate's formation conditions while preserving its CH volumetric storage.

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γ- and δ-alumina are popular catalyst support materials. Using a hydrothermal synthesis method starting from aluminum nitrate and urea in diluted solution, spherical core-shell particles with a uniform particle size of about 1 μm were synthesized. Upon calcination at 1000 °C, the particles adopted a core-shell structure with a γ-alumina core and δ-alumina shell as evidenced by 2D and 3D electron microscopy and 27Al magic angle spinning nuclear magnetic resonance spectroscopy.

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Strongly Reducing (Diarylamino)benzene-Based Covalent Organic Framework for Metal-Free Visible Light Photocatalytic HO Generation.

J Am Chem Soc

November 2020

COMOC - Center for Ordered Materials, Organometallics and Catalysis, Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent, Belgium.

Photocatalytic reduction of molecular oxygen is a promising route toward sustainable production of hydrogen peroxide (HO). This challenging process requires photoactive semiconductors enabling solar energy driven generation and separation of electrons and holes with high charge transfer kinetics. Covalent organic frameworks (COFs) are an emerging class of photoactive semiconductors, tunable at a molecular level for high charge carrier generation and transfer.

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Ammonia is an industrial large-volume chemical, with its main application in fertilizer production. It also attracts increasing attention as a green-energy vector. Over the past century, ammonia production has been dominated by the Haber-Bosch process, in which a mixture of nitrogen and hydrogen gas is converted to ammonia at high temperatures and pressures.

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A protocol for the detection of trace amounts of quartz in amorphous silica gels by NMR spectroscopy was developed and tested on commercially available samples. Using natural abundance Si MAS NMR spectroscopy with CPMG acquisition and standard addition of crystalline quartz, quantitative detection of quartz concentrations down to 0.1% wt.

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In this study the structure directing effect of a gemini-type piperidine-based multi-ammonium surfactant during hydrothermal zeolite synthesis was investigated for two cases: with and without a source of aluminum. The absence of an aluminum source led to the formation of an amorphous mesoporous MCM-48 type silica material, while the presence of aluminum guaranteed the formation of zeolite beta with a hierarchical pore system. The two opposing cases were studied in a time and temperature-dependent manner.

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High-Performance CO-Selective Hybrid Membranes by Exploiting MOF-Breathing Effects.

ACS Appl Mater Interfaces

January 2020

Center for Surface Chemistry and Catalysis , University of Leuven, Celestijnenlaan 200F , Post Box 2461, B3001 Leuven , Belgium.

Conventional CO separation in the petrochemical industry via cryogenic distillation or amine-based absorber-stripper units is energy-intensive and environmentally unfriendly. Membrane-based gas separation technology, in contrast, has contributed significantly to the development of energy-efficient systems for processes such as natural gas purification. The implementation of commercial polymeric membranes in gas separation processes is restricted by their permeability-selectivity trade-off and by their insufficient thermal and chemical stability.

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By using flexible metal organic frameworks such as MIL-53(Al), the selective uptake of 4-methylguaiacol was achieved from a simulated bio-oil (40 wt%). Similar high uptake capacity of phenolics (27 wt%) was observed from a real pyrolysis bio-oil, with good selectivity towards a variety of phenolics, e.g.

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Stand-alone and portable lab-on-chips (LOC) can be obtained by exploiting capillary flow in porous media. Polymethylmethacrylate (PMMA) platforms obtained through powder-based three-dimensional (3D) printing are appropriate for capillarity-driven LOCs. However, fluid flow in such platforms needs to be characterized well.

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Sensitivity improvement in 5QMAS NMR experiments using FAM-N pulses.

Solid State Nucl Magn Reson

August 2019

School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St Andrews, St Andrews, KY16 9ST, UK. Electronic address:

The multiple-quantum magic-angle spinning (MQMAS) experiment is a popular choice for obtaining high-resolution solid-state NMR spectra of quadrupolar nuclei with half-integer spin quantum number. However, its inherently poor sensitivity limits its application in more challenging systems. In particular, the use of higher-order multiple-quantum coherences, which have the potential to provide higher resolution in the isotropic spectrum, results in a further decrease in sensitivity.

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