Steam reforming of acetic acid over Ni-based catalysts derived from La1−xCaxNiO3 perovskite type oxides

Abstract Ni/CaO-La2O3 catalysts generated by in situ reduction of La1−xCaxNiO3 perovskite systems (x = 0; 0.15; 0.30 and 0.50) were prepared and evaluated in steam reforming of acetic acid under steady state conditions. The objective of this work was to study the effect of calcium content towards activity and syngas formation in such catalytic systems. The catalytic materials were characterized by in situ X-ray diffraction and temperature programmed reduction. The catalytic activity was evaluated in a packed bed reactor in a temperature range from 400 to 700 °C for LaNiO3 reduced samples and at 600 °C for the La1−xCaxNiO3 reduced precursors. The tests indicated that the presence of calcium oxide directly promotes hydrogen formation, by permitting a greater amount of water to be converted and limits the occurrence of ketonization

Palladium-supported catalysts in methane combustion: comparison of alumina and zirconia supports

Palladium catalysts supported on alumina and zirconia were prepared by the impregnation method and calcined at 600 and 1000 ºC. Catalysts were characterized by BET measurements, XRD, XPS, O2-TPD and tested in methane combustion through temperature programmed surface reaction. Alumina supported catalysts were slightly more active than zirconia supported catalysts, but after initial heat treatment at 1000 ºC, zirconia supported palladium catalyst showed better performance above 500 ºC A pattern between temperature interval stability of PdOx species and activity was observed, where better PdOx stability was associated with more active catalysts

Synthesis and characterization of perovskites LaMnO3 and γ-alumina as catalysts for methane combustion reaction

<p></p><p>ABSTRACT Perovskite-type Catalysts, LaMnO3, were synthesized by citrate and coprecipitation methods. Some of these materials was supported on γ-alumina or impregnated with Pd and/or Sn by wet impregnation, in 1% mass concentration. The catalysts were evaluated in the reaction of methane total combustion, and its activity measured by temperature programmed surface reaction (TPSR). The samples were heated to 800°C at a rate of 10°C / min under a flow rate of 50 mL / min of a mixture containing CH4, O2 and N2 at molar concentrations of 4%, 1% and 95 %, and He (50mL / min).As a standard of comparison, was synthesized also a reference sample PdO /γ-Al2O3. The samples were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and had its surface area measured by BET. The samples containing palladium were further analyzed in temperature programmed oxidation reaction (TPO) in order to determine the stability of PdO phases present in these materials. All samples were active to the methane combustion reaction, and the materials from citrate route higher than the coprecipitated material. The addition of palladium, even in low concentrations, was positive for catalytic activity, unlike tin, that resulted in a reduction in the final methane conversion for these materials.</p><p></p

Chemical pathways in the partial oxidation and steam reforming of acetic acid over a Rh-Al2O3 catalyst

The catalytic partial oxidation (CPO) and the steam reforming (SR) of acetic acid (HAc) over a 2wt% Rh/α-Al2O3 were investigated in an isothermal annular reactor. The experiments were performed at GHSV values up to 2.0×106 l(NTP)/kgcat/h by feeding highly diluted HAc/O2 and HAc/H2O mixtures; temperature was varied from 200 to 850°C. In analogy with the CPO of hydrocarbons, also the CPO of HAc showed a low temperature regime characterized by the oxidation of the acid, while the production of synthesis gas occurred above 450°C. Deep oxidation was observed below 300°C. In between 300 and 450°C, a progressive decline of O2 conversion was observed (a very unique feature), accompanied by decrease of CO2 production and formation of CO with traces of H2. C-accumulation was observed starting from 400°C. The data suggest that an increasing fraction of the surface sites was active in an oxygen-lean chemistry. This could be explained by assuming that competitive adsorption displaced oxygen in favor of acetic acid.Dedicated SR tests confirmed that the production of CO and H2 became significant only above 450-500°C, while the process was hindered, likely by C-poisoning, at lower temperatures.Raman measurements confirmed that at the intermediate temperatures (450°C) the surface was enriched by unsaturated C-species. The TPO profiles after CPO test at 450°C indicated a major peak at 350°C, suggesting the presence of C-species with intermediate reactivity or intermediate proximity to the metal particles, in between the highly reactive CHX fragments on metal sites and the polymeric C-species stored on the support

Pirólise rápida de biomassa de eucalipto na presença de catalisador Al-MCM-41

<p></p><p>ABSTRACT Latin America has considerable potential in the production of biomass, mainly for the use of its waste, Brazil being one of the most important representatives in the generation of energy from these renewable sources. In this sense, the paper approaches eucalyptus biomass, in the form of residue, as a promising source of low cost for the production of energy and chemical products. The objective of this work is to perform the fast pyrolysis at 500 °C in the presence of mesoporous Al-MCM-41 catalyst to evaluate the performance of the phases (bio-oil, biogas and bio-coal), as well as to analyze the products generated in the liquid phase using a gas chromatograph with a coupled mass spectrometer. The catalysts and the biomass were characterized by scanning electron microscopy (SEM) and X-ray fluorescence (FRX). Elemental analysis, immediate analysis, calorific value and thermogravimetric analysis were performed for eucalyptus. Bio-oil, bio-gas and bio-carbon yields were obtained, compatible with the literature, besides proving that the presence of the catalyst influences directly in this distribution. The main compounds identified were acetic acid, 1-hydroxy-2-propanone, 1-1-diethoxyethane, furfural, confirming the importance of the process for obtaining chemical products.</p><p></p