Carbon Dioxide Reduction on a Metal-Supported Solid Oxide Electrolysis Cell

Abstract

Using iACRES, which is an ironmaking system based on the Active Carbon Recycling Energy System concept, to reduce or recycle CO 2 emitted from ironmaking processes, we electrolyzed CO 2 with a metalsupported solid oxide electrolysis cell (MS-SOEC) capable of providing a large cell surface area for the processing of large amounts of CO 2. The MS-SOEC current-density-voltage (I-V) curves reveal a change in slope at around 0.8 V, which is the theoretical decomposition voltage of CO 2. The CO production rate was 0.88 μmol cm − 2 s − 1 when 2.0 V was applied between the cathode and the anode at 800°C, while that for O 2 was 0.44 μmol cm − 2 s − 1 , which is consistent with the stoichiometry for CO 2 electrolysis. The Faraday efficiency was 48% at 900°C. Gas was observed to leak from the cell; this leakage will need to be overcome through improvements in the layer-production process in order to achieve an efficiency close to 100%. On the basis of the cell-based experimental results, the feasibility of a blast furnace based on iACRES and driven by an HTGR (high-temperature gas-cooled reactor) was evaluated. To reduce CO 2 emissions by 30.0%, the required MS-SOEC surface area was estimated to be 8.30 × 10 4 and 3.98 × 10 4 m 2 with 968 and 480 MWth of HTGR thermal output under Faraday efficiency of 48% and 100%, respectively. We confirmed that iACRES using MS-SOEC contributes to realizing low-carbon ironmaking by recycling CO 2 and reducing its emissions into the atmosphere.

Progress in metal-supported solid oxide electrolysis cells: A review

“…Significantly higher performance was achieved recently by switching to a metal-supported design utilizing a much thinner 10 m thick electrolyte layer and SSC anode deposited by PLD, Fig. 4 CO2 electrolysis was also demonstrated with a YSZ-based cell deposited by plasma spray onto a 430 stainless steel mesh support [8]. The electrolyte was ~200 m thick and quite porous, resulting in low cell performance.…”

“…This is due to the similarity to standard solid oxide fuel cells utilizing hydrogen fuel [2], and the promise of utilizing hydrogen as an energy carrier throughout the economy [3]. A number of other electrolysis applications have been demonstrated with SOEC, including: ethylene production from methane [4]; co-electrolysis of carbon dioxide and steam to produce syngas or methane [5,6]; methane-assisted steam electrolysis to produce hydrogen with low electrical energy requirement [7]; and, carbon dioxide reduction to produce CO for further chemical reactions [8], or to generate oxygen from the Mars atmosphere for life support [9].…”

“…Low steam utilization conditions are also of interest, as stainless steel is expected to oxidize more quickly at higher steam content as discussed below in Section 3.1. Air is the oxidant atmosphere of choice due to the ease of implementing it in a lab setting, although nitrogen flush has also been used in one case [8]. In all cases so far, long-term operation was conducted galvanostatically at current density ranging from 0.166 to 0.8 A cm -2 .…”

“…The supports are sintered porous structures unless indicated otherwise. All used air on the anode side, except for[8] which used nitrogen. In many studies, performance at various conditions were reported, and a single representative point is shown here.…”

Development of Metal Supported SOEC for Carbon Recycling Iron Making System

“…18) Here, we proposed a metal-supported SOEC (MS-SOEC). 19) Since MS-SOEC is supported by metal, the area can be made larger and it can be stacked. Therefore, it is expected to achieve compaction and large-scale CO 2 reduction.…”