Search results for "LYST"

Electrocatalysis of the oxidation of methylenedioxyamphetamines at electrodes modified with cerium-doped zirconias

2004

The catalytic effect of monoclinic and tetragonal cerium-doped zirconias (m-CexZr1−xO2 and t-CexZr1−xO2, 0<x<0.10, respectively), prepared from gel precursors, on the oxidation of methylenedioxyamphetamine (MDA) and methylenedioxymetamphetamine (MDMA) at pH 7.0 has been studied. Upon attachment of synthetic specimens to polymer film electrodes, an oxidation peak near to +1.05 V vs AgCl/Ag appears that is unaffected by chloride ions and common interfering compounds, namely, dopamine, norepinephrine and ascorbic acid. The catalytic effect appears to be strongly influenced by crystallinity of specimens and coordination of cerium, increasing from the amorphous starting material to t-CexZr1−xO2 …

ChemInform Abstract: Rare Earth Metal Catalysts

2010

Host molecules containing electroactive cavities obtained by the molecular assembly of redox-active ligands and metal ions

1995

Self-assembly processes of nickel ions with the redox-active ligand 1,4,8,11-tetra(ferrocenylmethyl)-1,4,8,11-tetraazacyclotetradecane (Fc4cyclam) induces the formation of a redox-active cavity of potential use in electrocatalysis.

Cover Feature: Fundamental Insights into the Covalent Silane Functionalization of NiFe Layered Double Hydroxides (Chem. Eur. J. 29/2020)

2020

ChemInform Abstract: Enantioselective Mannich Reaction of β-Keto Esters with Aromatic and Aliphatic Imines Using a Cooperatively Assisted Bifunctiona…

2015

The title reaction tolerates aliphatic and aromatic substituents on both reaction partners, affording products (III) as a mixture of inseparable diastereomers with low or without any diastereoselectivity.

Gold catalysts supported on CeO2 and CeO2–Al2O3 for NO reduction by CO

2006

Abstract The reduction of NO x by CO was studied over gold catalyst supported on ceria and ceria–alumina. The mixed supports with different CeO 2 /Al 2 O 3 ratios were prepared by co-precipitation. The catalysts were characterized by means of XRD, TPR, XPS and Raman spectroscopy. The addition of alumina led to a slight enlargement of the gold particles, while the ceria particle size was decreased. Deeper oxygen vacancies formation in the presence of alumina was detected by TPR, XPS and Raman spectroscopy, compared to the pure ceria support. The samples exhibited a high and stable activity and 100% selectivity towards N 2 was reached at 200 °C.

Phase analysis and oxygen strorage capacity of ceria-lanthana-based TWC promoters prepared by sol-gel routes

2002

Ceria–lanthana-based promoters of three-way catalysts are synthesized by two different sol–gel routes, involving nitrate precursors. The oxygen uptake ability of these compounds is measured by O2 chemisorption. The specific surface area is determined by N2 adsorption (BET). X-ray diffraction data are analyzed by Rietveld refinement, demonstrating that lanthanum forms solid solution with CeO2; its total amount in ceria depends on the competitive formation of La–Al mixed oxides and on the synthetic method. The O2 uptake ability is essentially determined by the La content in the ceria–lanthana solid solution, while it is independent on the surface area and on the CeO2 particle size. The O2 upt…

The chloro‐substituent enhances performance of 2,4‐bis (imino)pyridylchromium catalysts yielding highly linear polyethylene

2020

The five unsymmetrical 2‐[1‐(2,4‐dibenzhydryl‐6‐chlorophenylimino)ethyl]‐6‐[1‐(arylimino)ethyl]pyridine compounds (aryl: 2,6‐Me2Ph L1 , 2,6‐Et2Ph L2 , 2,6‐i Pr2Ph L3 , 2,4,6‐Me3Ph L4 and 2,6‐Et2–4‐MePh L5 ) were prepared and characterized with FT‐IR and 1H/13C NMR spectroscopy as well as elemental analysis. The treatment of L1 – L5 with CrCl3·3THF affords the corresponding chromium chloride complexes (Cr1 – Cr5 ) in excellent yields. The molecular structures of Cr2 and Cr3 characterized by X‐ray diffraction show a distorted octahedral geometry with three nitrogen atoms and three chlorine atoms around the metal center. On activation with either MAO or MMAO, Cr1 – Cr5 collectively display hig…

Recyclable Catalyst Reservoir: Oxidation of Alcohols Mediated by Noncovalently Supported Bis(imidazolium)-Tagged 2,2,6,6-Tetramethylpiperidine 1-Oxyl

2013

Bis(imidazolium)-tagged 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) catalysts were adsorbed on different supports such as silica gel, silica gel modified with highly cross-linked polymeric imidazolium networks, and highly cross-linked polymeric imidazolium networks entrapping magnetic particles. These systems provided a convenient tool for the oxidation of both primary and secondary alcohols working as recyclable reservoirs for the bis(imidazolium)-tagged TEMPO catalysts. By using EPR spectroscopy it was demonstrated that the catalyst was released as the corresponding oxoammonium salt in the solution during the recycling step, thus promoting the oxidative process in a homogeneous fashion. …

Phase-distribution chromatography (PDC) of polystyrene

1970

A chromatographic technique is described where the stationary phase is a layer of a very high molecular polystyrene fraction (M = 107) on glass beads (ballotines). The mobile phase is cyclohexane passing the column at a constant temperature below the theta-temperature. A polystyrene sample of sufficiently low molecular weight (M ≤ 106) injected as a small plug at the top of the column is fractionated because the distribution between the mobile and the stationary phase depends on the molecular weight. Since the large molecules preferentially remain in the stationary phase, the smaller molecules leave the column first. The fractionation effect is inverse to that found in GPC experiments. The …