Estudo da oxidação parcial do metano a gás de síntese usando catalisadores de platina suportada

by Napolitano, Marcos Nogueira

Abstract (Summary)
Catalysts containing 1.5% (wt) of Pt supported in Nb2O5, LaCoO3, ZrO2,CeZrO2 e CeZrO2-M mesoporous were prepared and characterized using the followingtechniques: temperature programmed reduction (TPR), x-ray diffraction (XRD) andtemperature programmed desorption of CO2 e CO chemisorbed at room temperatureafter reduction at 500ºC under H2 flow. The catalysts were analyzed by partial oxidationand reforming of methane reactions with CO2 and H2O, at same temperature (800ºC),pression (1 atm) and space velocity (180000 h-1). The results showed that the magnitudeof conversion of methane during partial oxidation reaction decreased in the followingorder: Pt/CeZrO2 > Pt/CeZrO2-M > Pt/ZrO2 > Pt/LaCoO3 > Pt/Nb2O5 ≈ 0. Such resultswere in accordance with the evolution of existing redox/basic sites and with the balancebetween these sites and metallic interfacial sites.Reducibility of the catalysts follows the same order, except for Pt/LaCoO3,which was more reducible than Pt/ZrO2.A triangular scheme of mechanism, where direct and indirect steps of synthesisgas formation coexist, explains all the existing results, either modifying reactionalcondition or changing employed catalyst.The result of reforming of methane with CO2 and H2O revealed the followingincreasing order of activity: Pt/CeZrO2-M > Pt/CeZrO2 > Pt/ZrO2 >>> Pt/LaCoO3,Pt/Nb2O5 ≈ 0. They are coherent with the bifunctional mechanism, where the balancebetween metallic and redox sites was of key importance to obtain synthesis gas in aratio H2/CO = 2, as in partial oxidation.
This document abstract is also available in Portuguese.
Bibliographical Information:

Advisor:Ricardo Reis Soares

School:Universidade Federal de Uberlândia

School Location:Brazil

Source Type:Master's Thesis

Keywords:catalisadores metano oxidação de platina engenharia quimica


Date of Publication:02/21/2005

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