235 research outputs found
Elucidation of the mechanism of conversion of methanol and ethanol to hydrocarbons on a new type of synthetic zeolite
Molecular traffic control in single-file networks with fast catalysts
As a model for molecular traffic control (MTC) we investigate the diffusion
of hard core particles in crossed single-file systems. We consider a square
lattice of single-files being connected to external reservoirs. The (vertical)
alpha-channels, carrying only A-particles, are connected to reservoirs with
constant density ra. B-particles move along the (horizontal) beta-channels,
which are connected to reservoirs of density rB. We allow the irreversible
transition A to B at intersections. We are interested in the stationary density
profile in the alpha- and beta- channels, which is the distribution of the
occupation probabilities over the lattice. We calculate the stationary currents
of the system and show that for sufficiently long channels the currents (as a
function of the reservoir densities) show in the limit of large transition
rates non analytic behavior. The results obtained by direct solution of the
master equation are verified by kinetic Monte Carlo simulations.Comment: 11 page
Preparation, characterization and catalytic behavior for propanepartial oxidation of Ga-promoted MoVTeO catalysts
[EN] Two sets of Ga-promoted MoVTeO catalysts were synthesized hydrothermally and heat-treated at 600 degrees C in N-2: (i) materials prepared from gels with Mo/V/Te/Ga atomic ratios of 1/0.60/0.17/x (x=0-0.12) (A-series) and (ii) materials prepared from gels with Mo/V/Te/Ga atomic ratios of 1/0.60-x/0.17/x (x=0.15 or 0.25) (B-series). In addition, a Ga-containing MoVTeO catalyst was also prepared from M1-containing MoVTeO material by impregnation with aqueous solution of gallium and heat-treated at 450 degrees C in N-2. Catalysts were characterized by means of powder XRD, TEM, Raman spectroscopy, NH3-TPD and XPS and tested in the partial oxidation of propane. The results showed that the addition of small amount of gallium significantly increase the selectivity to acrylic acid (AA) at low propane conversion. However, at high propane conversion, the selectivity to AA strongly depends on both the catalyst composition and the gallium incorporation method. The higher selectivity to acrylic acid over Ga-containing MoVTeO catalysts has been related to: (i) structural changes in the M1 phase by the incorporation of Ga3+ into the octahedral structural framework and/or (ii) incorporation of Ga3+ species on the catalyst surface thus modifying catalysts acid properties. (C) 2014 Elsevier B.V. All rights reserved.Financial support from DGICYT in Spain (Project CTQ2012-37925-C03-1 and Program Severo Ochoa SEV-2012-0267) is gratefully acknowledged. EGG acknowledges finantial support through spanish project MAT2010-19837-C06-05 and the ICTS-Microscopia Electronica in Madrid for facilities.Hernández Morejudo, S.; Massó Ramírez, A.; García-González, E.; Concepción Heydorn, P.; López Nieto, JM. (2015). Preparation, characterization and catalytic behavior for propanepartial oxidation of Ga-promoted MoVTeO catalysts. Applied Catalysis A: General. 504:51-61. https://doi.org/10.1016/j.apcata.2014.12.039S516150
Toward better understanding of the catalytic action of acidic zeolites: investigation in methane and ethane activation and transformation
Selective Nanocatalysis of Organic Transformation by Metals: Concepts, Model Systems, and Instruments
Electron spin density distribution in the CO<sup>+</sup>, CO<sub>2</sub><sup>-</sup> and O<sub>2</sub><sup>-</sup> radicals as a function of geometry
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