Goede, A.

Kyriakou, V.

Middelkoop, V.

Neagu, D.

Pandiyan, A.

Sharma, R.

Tsampas, M. N.

Weber, S.

Welzel, S.

English

DIFFER: Publications

CO2 plasmolysis Oxygen Separator Solid Oxide Electrolyte Cell ARUNKUMAR PANDIYAN*, DRAGOS NEAGU**, VASILEIOS KYRIAKOU*, RAKESH SHARMA*, VESNA MIDDELKOOP***, SOPHIE WEBER****, ADELBERT GOEDE*, STEFAN WELZEL*, MICHAIL N. TSAMPAS*  * DIFFER, Dutch Institute for Fundamental Energy Research, Eindhoven, the Netherlands.  ** School of Chemical Engineering and Advanced Materials, Newcastle University, UK. *** VITO, Flemish Institute for Technological Research, Mol, Belgium.  **** Cerpotech, Ceramic Powder Technology, Trondheim, Norway. ELECTROCHEMICAL MEMBRANE REACTOR FOR OXYGEN SEPARATION AFTER CO2 PLASMOLYSIS Introduction  Plasmolysis is an energy efficient process for converting CO2 into CO and O2 towards reintroducing CO2 into energy and chemical cycles. The main bottleneck of this process is that CO remains mixed with O2 and residual CO2 [1]. Therefore, efficient gas separation and recuperation are essential for obtaining pure CO, which can be used to produce CO2-neutral fuels using water gas shift (WGS) and Fischer-Tropsch reactions. In the framework of European project KEROGREEN, we aim to overcome this obstacle and investigate a novel CO2 valorisation route to produce sustainable aviation fuel synthesised from H2O and CO2 powered by renewable electricity. Electrochemical Oxygen Separation Our approach is to electrochemically separate O2 by employing a solid oxide electrolysis cell (SOEC) as shown in Fig.1. The SOECs consist of perovskite electrode materials and yttria-stabilized zirconia based electrolyte. They exhibit remarkable properties, which can be fully utilized for gas-separation processes (downstream of plasma-reactor) in a cost-effective manner [2]. The main challenge of this concept is the optimization of the plasma electrode to exhibit (i) chemical and structural stability under CO2 plasma atmosphere and (ii) poor catalytic activity for the back reaction, i.e. CO oxidation. La/Sr-based perovskite oxygen electrode materials have been widely reported for SOEC application due to their excellent oxygen reduction reaction (ORR) activity and redox stability under operating conditions [2]. However, their catalytic activity towards CO oxidation at a high temperature as plasma electrode is yet to be explored. Thus, in present work, we examine the use of La/Sr based material as plasma exposed electrode by following a three-step approach, i.) Evaluation of the catalytic activity in powder samples in a straightforward gas stream, ii.) Electrocatalytic activity in SOECs and iii.) Performance under CO2 plasmolysis conditions.  Experimental  The perovskites that were screened in our study were prepared using the spray pyrolysis technique by Cerpotech. After an extensive pre-assessment of potential materials with low CO oxidation activity [3], Zn and Ga doped lanthanum strontium titanates (LSZT, LSGT) were fabricated and subsequently compared with standard electrode materials optimized for conventional SOECs applications, i.e La0.8Sr0.2MnO3 (LSM), La0.6Sr0.4Co0.2Fe0.8O3 (LSCF), La0.75Sr0.25Cr0.5Mn0.5O3 (LSCM). All samples were physicochemically characterized using SEM, XRD and BET techniques. The catalytic performance was evaluated with the temperature programmed oxidation experiments (100 to 850°C, with 5oC/min), using a fixed bed quartz reactor loaded with 200 mg of pre-sintered (at 1100oC for 2 h) material. The CO2 and CO were continuously recorded using an IR analyser.  Results and discussion  The oxygen separation process from gas mixture (7%CO2, 3%CO and 1.5%O2) will be performed using SOEC. Hence, the initial screening of materials was meant to identify the plasma exposed electrode with reduced catalytic activity towards the CO oxidation and selectivity for oxygen reduction reaction. Following, three parameters were used to quantify the catalytic performance towards the back reaction: Temperature at which 5% (ignition point) and 50% of CO conversion are achieved (T5% and T50% respectively). The CO conversion at nominal SOEC operating temperature (To=700°C ).  LSGT and LSZT catalytic performance were fairly low, while LSM, LSCF and LSCM show very high activity even at low temperature (Fig. 2.). At To, both LSGT and LSZT shows reduced CO conversion rate of 23% and 18% respectively. The obtained results suggest that both LSGT and LSZT are suitable for plasma facing electrode in SOEC. Further electrochemical studies with LSGT and LSZT are required to identify the best candidate for the electrochemical oxygen separator in the plasma process.  Conclusions   The KEROGREEN project could lead to a renewable way to develop sustainable fuel for the future aviation industry. In this work, we focus on developing materials with reduced catalytic activity towards the CO oxidation as well as increased ORR activity towards oxygen molecule. Among the studied materials, LSGT and LSZT are found to be the best candidates for electrochemical (SOEC) oxygen separation after CO2 plasmolysis. Acknowledgment The KEROGREEN project receives funding from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement 763909.  References: [1] A. Fridman, Plasma Chemistry; Cambridge University Press, 2008 [2] J.T. Irvine, D. Neagu, M.C. Verbaeken, C. Chatzichristodoulou, C. Graves, M.B. Mogensen, Nature Energy, 1 15014 (2016) 1-13. [3] D. Neagu, PhD thesis (2012) 

Electrochemical membrane reactor for oxygen separation after CO2 plasmolysis

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Electrochemical membrane reactor for oxygen separation after CO2 plasmolysis

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