Showing papers in "Journal of Catalysis in 1988"

TL;DR: In this paper, the photooxidation rate of 22 organic solutes over a UV illuminated film of Degussa P25 titanium dioxide was studied over a 100-fold concentration range for each solute, generally from about 1 to 100 mg liter−1.

TL;DR: In this paper, a van der Waals model for the interaction energy and the sticking force of a molecule lodging in a pore is used to rationalize semiquantitatively a number of well-accepted observations, e.g., the role of zeolites as molecular traps, the origin of the surface barrier postulated to reconcile the large divergence between intracrystalline (self-diffusion) and macroscopically measured (nonequilibrium) diffusion coefficients; the rapid diffusion of molecules in tight-fitting zeolite pores; the window effect observed for

TL;DR: In this paper, a photocatalytic decomposition of H2O to form H2 and O2 over NiOK4Nb6O17 powder (1-10 μm, band gap = 3.3 eV), which is an ion-exchangeable layered compound, proceeds steadily more than 50 h under the bandgap irradiation.

TL;DR: In this paper, a new model was proposed to explain carbon filament growth on supported transition metal catalysts, based on the assumption that an unstable bulk carbide governs the filament growth, and the new model explains all observations and agrees with available thermodynamic equilibrium data, providing in a natural way a driving force for the migration of carbon atoms through the catalyst particle.

TL;DR: Vanadium-magnesium oxides were found to be active and selective catalysts for the oxidative dehydrogenation of propane to propene as discussed by the authors, achieving a selectivity of up to 65% at 10% conversion, but decreased with increasing conversion.

TL;DR: In this paper, the authors deal with the adsorption and temperature-programmed reaction spectroscopy of (i) formaldehyde on polycrystalline copper, poly-stalline zinc oxide and (ii) methanol on a copper/zinc oxide/alumina (60:30:10) catalyst.

TL;DR: In this article, the effects of adding CeO2 to PdAl2O3 as a catalyst modifier were investigated by X-ray photo-electron spectroscopy and Xray diffraction.

TL;DR: In this paper, the effects of pore structure and experiments designed to concentrate the oxides in either the smaller (~9 nm) or the larger pores (15-30 nm) were examined.

TL;DR: In this article, a new method for preparation of high-specific-surface (60-400 m2/g) SiC is described, which consists of the attack of high specific-surface activated carbon by SiO vapor generated by the high-temperature reaction of Si and SiO2.

TL;DR: In this article, a temperature-programmed reaction (TPR) of MoO 3 with ammonia producing first Mo 2 N which was subsequently converted to α-MoC 1− x by TPR with a CH 4 /H 2 mixture.

TL;DR: In this paper, the addition of sufficient amounts of cerum oxides (≥2 wt% Ce) to the Rh/Al 2 O 3 catalyst was found to cause the following changes in CO oxidation kinetics: suppression of the CO inhibition effect, decreased sensitivity of the reaction rate to gas-phase O 2 concentration, and decreased apparent activation energy.

TL;DR: The poisoning effect of nonsterically hindered nitrogen compounds, expressed as inhibition adsorption constants derived from Langmuir-Hinshelwood kinetics for thiophene hydrodesulfurization (HDS), correlated well with gas-phase basicity (proton affinity).

TL;DR: In this paper, a model is proposed to interpret the influence of the doping oxide: the thermal stabilization is related to the presence of LnAlO3 microdomains in the corundum nucleation sites.

TL;DR: In this article, the partial oxidation of methane to formaldehyde by molecular oxygen has been studied, with molybdenum(VI) oxide-silica and related catalysts.

TL;DR: In this article, the effects of various parameters on the photoassisted reduction of silver ions to metallic deposits on powder titanium dioxide has been studied, and it was shown that the initial deposition rate varied with the starting concentration of Ag+ ions according to a Langmuir-Hinshelwood mechanism, and was almost independent of the temperature around 300 K.

TL;DR: In this article, the number of acid sites was investigated by thermogravimetry of adsorbed pyridine, and the types of acid site were examined by infrared spectroscopy of adhesives of the material, showing that both Lewis and Bronsted acid sites were present on the surfaces of V2O5 and MoO3.

TL;DR: In this article, the authors investigated the role of temperature-programmed reduction (TPR), desorption (TPD), and extended X-ray absorption fine structure (EXAFS) on the formation of Pt particles and the influence of H+ and added metal cations on it.

TL;DR: In this article, the electronic structure of zeolites was systematically investigated by utilizing XPS, and the basic strength of framework oxygen increases with increasing Al content regardless of the crystal structure and with the decreasing electronegativity of the counter cation.

TL;DR: In this article, the effect of support on the catalytic activity and properties of molybdenum sulfide catalysts was investigated in order to obtain the fundamental information necessary for designing better hydrotreating catalysts.

TL;DR: In this paper, a fixed-bed flow reactor, operating at atmospheric pressure, achieved a 45% C 2 (sum of ethane and ethylene) selectivity at a 33% methane conversion over 2.0 g of 15 wt% Na CaO catalyst at 725 °C with a gas mixture of CH 4 O 2 = 2.

TL;DR: In this article, simple devices were described for the purification of water combining adsorption of organic impurities with in situ photocatalytic oxidation regeneration of the adsorbent/photocatalyst.

TL;DR: The kinetic significance of C1 aldehydic species such as adsorbed formyl and formaldehyde is supported by experimental evidence and theoretical calculations in this paper, where the C1 coupling mechanism overrides various CO insertion paths to ethanol over the present Cs/Cu/ZnO catalyst.

TL;DR: In this paper, the effects of potassium on ammonia synthesis over model iron single-crystal catalysts of (111), (100), and (110) orientation have been studied under high-pressure reaction conditions (20 atm reactant pressure of nitrogen and hydrogen).

TL;DR: In this paper, the metal-support effect responsible for higher CO hydrogenation rates over certain metal/TiO 2 catalysts represents a phenomenon capable of activating carbonyl bonds in general.

TL;DR: In this paper, a survey on the effects of varying several operating conditions shows that under certain conditions significant gas-phase oxidative coupling can occur in the absence of catalysts, and the implications that the observed results might have on catalytic oxidative coupling of methane have also been considered.

TL;DR: In this paper, the authors measured the rate of CH3OH synthesis on a series of Cu ZnO and related catalysts prepared by different techniques under reaction conditions of 523 K, 50 atm, and H2/CO/CO2 = 70/24/6.

TL;DR: In this article, a series of silica and alumina-supported Pt catalysts of widely varying mean particle size was studied and a correlation of the oxidation extent (as measured by temperature-programmed reduction) with mean particle radius (as determined from chemisorption measurements) was determined.

TL;DR: Stoltze and Norskov as mentioned in this paper showed that the largest contribution to the activation enthalpy for the catalytic synthesis of NH3 at high pressures is the energetic cost of creating two free sites on the surface of the working catalyst.

TL;DR: In this paper, a linear correlation has been found between the statistical amount of three-coordinatively unsaturated molybdenum ions in the (1010) edge plane of the MoS2 slabs and hydrogenation activity.

TL;DR: In this paper, the authors have chosen the HDN of quinoline at moderately high pressure as a model reaction, and they have used the same carbon-supported transition metal sulfide catalysts studied by Vissers et al.