Claudia E. Quincoces

Effect of addition of CaO on Ni/Al2O3 catalysts over CO2 reforming of methane

The Ni/γ–Al2O3 catalyst was modified by CaO in order to improve the thermal stability and the carbon deposition resistance during the CO2 reforming of methane to syngas reaction. The catalytic performance, thermal stability, structure, dispersivity of nickel and carbon deposition of the modified and unmodified catalysts were investigated by a series of characterization techniques (X-ray diffraction (XRD), BET, H2 chemisorption, temperature programmed reduction (TPR) and flow-reaction). Results showed that catalysts modified with CaO improve their stability better than the nickel-based catalysts.

Role of Mo in CO2 reforming of CH4 over Mo promoted Ni/Al2O3 catalysts

A series of Ni/Al2O3 catalysts modified by Mo was prepared to show the effect of preparation sequence and reduction step on catalytic properties as well as the thioresistance and carbon deposition during CO2 reforming of methane. The catalysts were prepared by successive impregnations with Ni and Mo salts (2% p/p Ni and Mo/Ni=0.06). The solids were activated by reduction in pure H2 and H2/He (1:10) mixture. The results indicate that a low amount of Mo sensibly increased the resistance to sulfur and led to a decrease in carbon deposition.

Studies on H2S Adsorption and Carbon Deposition Over Mo-Ni/Al2O3 Catalysts

The influence of molybdenum on the CO2 reforming of methane, simultaneous sulphur poisoning and carbon formation over alumina-supported Ni catalysts was studied. A series of Ni/Al2O3 catalysts modified by Mo was prepared to enable the effect of molybdenum content on H2S adsorption and the catalytic properties of the solids to be studied. The atomic Mo/Ni ratio in such catalysts varied in the range 0.01–1.00 while the Ni content was maintained constant at 3.3%. The catalysts were characterized by TPR, hydrogen adsorption and TEM methods. The H2S adsorption capacities of the catalysts were determined at 923 K employing a mixture consisting of 50 ppm H2S in a hydrogen stream. The results obtained indicate that the Mo promoter had a very favourable influence on the sulphur resistance of the Ni-based catalyst and led to a reduction in the rate of carbon deposition and the formation of graphitic species over the same.

Preparation of supported Cu/ZSM-5 zeolite films for DeNOx reaction

Abstract This work reports the in situ synthesis of ZSM-5 zeolite films on cordierite and the performance of a Cu/ZSM-5-coated monolithic catalyst in the lean NO x reduction reaction. At the end of the hydrothermal crystallization, a zeolite/cordierite composite was obtained which consists of a continuous zeolite film that strongly attaches to the sustrate surface. The monolithic catalysts so prepared are active for the reduction of NO.

Ni/γ-Al2O3 catalyst from kaolinite for the dry reforming of methane

Abstract A catalyst consisting of a 5% Ni over a γ-Al 2 O 3 novel support was evaluated under high-temperature reaction conditions. The γ-Al 2 O 3 -rich phase was obtained by selective dissolution of siliceous components of heat-treated kaolinite. The support was appropriate to prepare a catalyst with high surface area (170 m 2 /g) that showed to be active and stable for dry reforming of methane at 650 °C and a CH 4 /CO 2 =0.5 molar ratio. Compared to the conventional Ni/α-Al 2 O 3 catalyst, this new material showed an improved sulfur resistance when it was reduced in hydrogen steam at the reaction temperature. In industrial conditions, CH 4 /CO 2 =1, deactivation by carbon deposition was not increased. The content and type of deposited carbon were analyzed by TPH and TPO techniques. As regeneration methods of the coked catalysts, hydrogen and oxygen carbon treatments were employed. After the treatment with hydrogen the catalyst reaches the initial activity, but with oxygen the activity only is partially regenerated.

CO2 reforming of CH4 over Mo promoted nickel-based catalysts

Abstract It has been studied the effects of Mo addition on the stability, the sulfur poisoning and carbon deposition over Ni based catalysts for CO 2 reforming of methane. The Ni catalysts promoted with small amount of Mo increases the stability of the catalyst and decreases the carbon deposition. In order to characterize the carbon deposited on the catalysts during CO 2 reforming reaction, TEM and TPO experiments were carried out after reaction. Formation of filamentous carbon was determined. In the presence of H 2 S containing feeds (0.1 ppm), Ni thioresistance also increases with Mo content.

Effects of reduction and regeneration conditions on the activity of CuO-ZnO catalysts

The influence of thermal and hydrothermal treatments and reduction processes on the activity of CuO-ZnO catalysts was studied. Temperature-programmed reduction (TPR) was used in the study of catalyst activation with different reduction mixtures. A mixture of H2 and N2 in the range of 500 to 573 K was the most effective reducing agent. High temperature, water vapor and a high partial pressure of hydrogen enhance Cu sintering and Cu-Zn alloy formation, with a decrease in catalytic activity. XRD analysis of reactivated catalysts showed that their deactivation can be related to the formation of surface spine species. Reoxidation at 623 K and subsequent reduction of the aged catalyst led to metal redispersion but not catalyst regeneration.

Effect of Rh addition on activity and stability over Ni/γ-Al2O3 catalysts during methane reforming with CO2

Abstract The effect of low Rh contents was studied in Ni/γ-Al 2 O 3 catalysts. Activity, stability and carbon deposition on these catalysts were analyzed for methane reforming with CO 2 . Catalysts were characterized by XRD, TGA, TPR and flow-reaction. Results indicated that the catalyst promoted by Rh showed a higher activity and a similar carbon deposition than the Rh and Ni monometallic catalysts. Rh addition favors an interaction compound in the Rh-Ni/γ-Al 2 O 3 that would improve the methane reforming activity of the supported Ni-based catalysts.

Zr-supported CuFe 2 O 4 Nanoparticles as Catalysts for the Combustion of Propane

Fil: Lavat, Araceli. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingenieria Olavarria; Argentina

Preparation and Characterization of Supported Vanadia Catalyst for the Selective Catalytic Reduction of NO with NH3

The structure characteristics and the catalytic behavior are analyzed on catalysts obtained by oxidative degradation of a planar VO complex on alumosilicate support (cordierite). By means of different techniques (FTIR, DRX, TGA), vanadium oxide formation was determined during the thermal decomposition of the organometallic precursor and the formation of NH4 species during the reaction. Besides, the catalytic activity was also determined for the selective reduction of NO with ammonia.