resumo
The stability and oxygen permeability of dense tubular membranes, made of (SrFeO(3-infinity))(0.7)(SrAl(2)O(4))(0.3) (SFSA) composite by cold isostatic pressing, were assessed under air/CO(2) and air/(CH(4) + CO(2)) gradients at 973-1173K. Mixed-conducting SFSA, comprising SrFe(Al)O(3-delta) perovskite-like and SrAl(2)O(4)-based phases, was selected as a model membrane material for the natural gas conversion reactors due to its attractive oxygen transport, catalytic and thermomechanical properties. As partial dissolution of SrAl(2)O(4) in the perovskite-like component leads to strontium deficiency of the perovskite phase, the composite exhibits an improved stability with respect to interaction with CO(2), although thermogravimetric analysis showed that carbon dioxide adsorption on SFSA is still significant. No degradation was revealed in the course of oxygen permeation tests during 200-300 h with subsequent scanning electron microscopy inspection. However, contrary to that observed for SFSA powders, methane conversion in the tubular SFSA membranes without surface modification results in predominant total combustion caused by the slow kinetics of the reforming reactions. Significantly higher conversion efficiency and synthesis gas yields were achieved passing the pre-reacted gas mixtures into an additional reactor with Pt/LaNiO(3)/Al(2)O(3) catalyst bed at the tubular membrane outlet. (C) 2008 Elsevier B.V. All rights reserved.
palavras-chave
METHANE OXIDATION; THERMOMECHANICAL PROPERTIES; OXYGEN PERMEABILITY; ION-TRANSPORT; SYNTHESIS GAS; CONVERSION; STABILITY; PERMEATION; DENSE; CO2
categoria
Engineering; Polymer Science
autores
Yaremchenko, AA; Kharton, VV; Valente, AA; Snijkers, FMM; Cooymans, JFC; Luyten, JJ; Marques, FMB
nossos autores
Aleksey Yaremchenko
Investigador Principal
Anabela Tavares Aguiar Valente
Investigador Principal
Fernando Manuel Bico Marques
Professor Catedrático