Lisiane V. Mattos

Production of hydrogen from ethanol: review of reaction mechanism and catalyst deactivation.

Mechanism and Catalyst Deactivation Lisiane V. Mattos,† Gary Jacobs,‡ Burtron H. Davis,‡ and Fab́io B. Noronha* †Departamento de Engenharia Química e de Petroĺeo, Universidade Federal Fluminense (UFF), Rua Passo da Pat́ria, 156-CEP 24210-240, Niteroí, RJ, Brazil ‡Center for Applied Energy Research, The University of Kentucky, 2540 Research Park Drive, Lexington, Kentucky 40511, United States Instituto Nacional de Tecnologia−INT, Av. Venezuela 82, CEP 20081-312, Rio de Janeiro, Brazil

Partial oxidation of methane on Pt/Ce–ZrO2 catalysts

The mechanism of partial oxidation of methane was studied on Pt/Al2O3, Pt/ZrO2 and Pt/Ce–ZrO2 catalysts. The reducibility and oxygen transfer capacity were evaluated by temperature programmed reduction (TPR) and oxygen storage capacity (OSC). The effect of the support on the cleaning mechanism of the catalyst surface was investigated by the sequence of CH4/O2 pulses. Moreover, temperature programmed surface reaction (TPSR) measurements were performed to evaluate the reaction mechanism. Pt/Ce–ZrO2 catalysts proved to be more active, stable and selective than Pt/Al2O3 and Pt/ZrO2 catalysts. The results were explained by the higher reducibility and oxygen storage/release capacity of Pt/Ce–ZrO2 catalysts, which allowed a continuous removal of carbonaceous deposits from the active sites, favoring the stability and activity of the catalysts, as revealed by the CH4/O2 pulses. TPSR experiments showed that the partial oxidation of methane proceeded through a two-step mechanism.

The Effect of Metal Type on Hydrodeoxygenation of Phenol Over Silica Supported Catalysts

Different metals supported on SiO2 were tested for the hydrodeoxygenation of phenol. For Pt/SiO2, Pd/SiO2 and Rh/SiO2 catalysts, phenol is mainly tautomerized, followed by hydrogenation of the aromatic ring. The direct dehydroxylation of phenol followed by hydrogenolysis is favored over more oxophilic metals (Ru, Co and Ni).Graphical Abstract

Nickel / Doped Ceria Solid Oxide Fuel Cell Anodes for Dry Reforming of Methane

In this work, the catalytic performance of Ni supported on ceria doped with Zr, Pr and Nb used as anodes for solid oxide fuel cell (SOFC) operating directly on fuels containing methane and CO2 was studied. The anodes were prepared by a hydrothermal method using a Ni content (14 vol%) lower than that of a conventional SOFC anodes (30 vol%). The materials obtained were characterized by X-ray diffraction, temperature-programmed reduction, Raman spectroscopy and thermogravimetric analyses. The results showed that the sample containing Zr exhibited the lowest Ni crystallite size, which led to a high initial activity on dry reforming of methane at 1073 K. However, the Ni/CePr catalyst showed the lowest carbon formation. This was attributed to the higher oxygen mobility of CePr support that promotes the carbon removal mechanism.

Comparison of two different synthesis methods of perovskites, SrCo0.5FeO3 type, aiming at evaluating their use as membranes for partial oxidation of methane

In this work two different synthesis methods of perovskites, SrCo0.5FeO3, were compared: combustion synthesis and oxides mixture aiming at evaluating their use as membranes for partial oxidation of methane. The combustion synthesis method explores an exothermic, generally very fast and self-sustaining chemical reaction between the desired metal salts and a suitable organic fuel, which is ignited at a temperature much lower than the actual phase formation temperature. The oxides mixture are based on a physical mixture of the powder oxides followed by calcination to obtain the desired phase. In order to obtain the membranes, we studied the conformation of bodies and the temperatures of sintering in the two powders synthesized. The powders were analyzed by density and grain size distribution and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). After conformation, in cylindrical form, the green bodies were analyzed by density. After sintering at 1150 °C, the membranes were analyzed by density and they were characterized by XRD and SEM. The powder obtained by combustion synthesis shows lower density and fine grains than the other obtained by oxides mixture. The membranes obtained present very different morphology depending on the precursor powder synthesis. The sintered membranes obtained by combustion method also present a very uniform morphology without segregation.

Autothermal Reforming of Methane under low Steam/Carbon ratio on supported Pt Catalysts

Abstract Pt/Ce 0.75 Zr 0.25 O 2 , Pt/Ce 0.14 Zr 0.86 O 2 and Pt/CeO 2 catalysts proved to be more stable than Pt/Ce 0.50 Zr 0.50 O 2 , Pt/CeO 2 (prec), Pt/ZrO 2 and Pt/Al 2 O 3 catalysts on the autothermal reforming of methane under low S/C ratio (0.2). The results showed that the good stability of the Pt/Ce 0.75 Zr 0.25 O 2 , Pt/Ce 0.14 Zr 0.86 O 2 and Pt/CeO 2 catalysts is related to a proper amount of oxygen available per metal-support interfacial area on these materials. The high reducibility and oxygen storage/release capacity of support promotes the mechanism of continuous removal of carbonaceous deposits from the active sites, which takes place at the metal-support interfacial perimeter.

The effect of pt loading and space velocity on the performance of Pt/CeZrO2/Al2O3 catalysts for the partial oxidation of methane

Abstract In this study, the perfomance of Pt/CeZrO 2 /Al 2 O 3 with Pt loadings of 0.5, 1.0 and 1.5 wt on the partial oxidation of methane was evaluated. The results showed that the increase of metal content caused a decrease of the metal dispersion, but it did not affect the catalysts reducibility properties. The methane conversion and CO selectivity increased with the use of higher Pt content. The deactivation observed for the lower Pt contents could be due to the unbalance between methane decomposition and oxygen transfer process. The increase of space velocity decreased the catalyst stability and selectivity for H 2 and CO.

The performance of pt/cezro2/al2o3 catalysts on the partial oxidation and autothermal reforming of methane

Abstract The goal of this work was to evaluate the effect of the support calcination temperature (1073, 1173 and 1273 K) on the Pt/CeZrO 2 /Al 2 O 3 performance on the partial oxidation and autothermal reforming of methane. The sample calcined at 1273 K was less stable on the partial oxidation of methane probably due to the smaller contact between mixed oxide and Pt on the alumina surface, which favors the coke deposition. Moreover, for all samples, the addition of water led to a better activity and stability on autothermal reforming of methane.