COGENERATION OF C2 HYDROCARBONS AND ELECTRICAL POWER FROM METHANE USING SOLID OXIDE FUEL CELL TYPE REACTOR

Abstract

This work developed the new anode catalysts for co-generation of C2 hydrocarbons and electric power from methane. The study is divided into 2 parts in two different types of reactor: 1) Fixed bed reactor (FBR) and (2) Solid oxide fuel cell reactor (SOFC). In part 1, the experiments were performed using co-feeds of methane, oxygen and nitrogen inert gas molar ratio of 4:1:5 at various temperatures (700-900 oC). Three types of catalysts; Au/La0.6Sr0.4MnO3 (Au/LSM), La0.25Sr0.75Cr0.5Mn0.5O3 (LSCM) and LiFeO2 (LFO), have been investigated. The catalyst was doped with ceria in order to improve its catalytic activity. The results indicated that the addition of Ce promoter could promote the C2 selectivity. In part 2, La0.8Sr0.2MnO3 (LSM) and La0.8Sr0.2FeO3 (LSF) were uses as the cathode while 8 mol% yttria-stabilized zirconia (8YSZ) was used as the electrolyte. The various types of electrode catalyst for anode have been investigated. Membrane cell has been fabricated by the tape casting and solution impregnation method. For the anode catalyst, the CeO2-LSCM infiltrated provided the excellent electrode performance. Ce/LSCM catalyst provided the C2 selectivity of 85%, CH4 conversion of 3.4%, and the maximum power densities of 221 mW.cm-2 at 800oC under a load of 0.3 V. In case of LFO catalyst, it was suitable to operate under the temperature lower than 800 oC. The La0.9Sr0.1Ga0.8Mg0.2O3 (LSGM) has been used as the electrolyte at low temperature operation. It provided the CH4 conversion of 3.1%, C2 selectivity of 85.2% and the maximum power densities of 38 mW.cm-2 at 750oC under a load of 0.3 V.