Methane Synthesis Characteristics of H_2O/CO_2 Co-electrolysis in Tubular Solid Oxide Electrolysis Cells

摘要

Producing methane by H_2O/CO_2 co-electrolysis through solid oxide electrolysis cell (SOEC) is a promising method to store unstable renewable power and reduce CO_2 emission simultaneously. In this paper, CH_4 synthesis characteristics in tubular SOEC (TSOEC) is studied in the temperature range of 550-650°C by combining experiment and simulation. Experiments demonstrate that adding H_2 increases CH_4 production ratio from 0 to 4.01% at 600°C. Besides, electricity significantly promotes CH_4 production, especially when H_2 is added. The voltage of 1.5 V increases CH_4 production ratio by ＜0.04% in the absence of H_2. But when 20% H_2 is fed in cathode, a voltage of 1.5 V can increase CH_4 production ratio by 3-4%. Finally, chemical reactions, thermal distribution and optimal operating condition are simulated by a well validated thermal model. A reasonable thermal distribution created by operating TSOEC in counter-flow mode and lower inlet steam partial pressure can dramatically improve CH_4 production.