Contents lists available at ScienceDirect Applied Catalysis B: Environmental journal homepage: www.elsevier.com/locate/apcatb Activity and stability of powder and monolith-coated Ni/GDC catalysts for CO 2 methanation Antonio Vita a, ⁎ , Cristina Italiano a , Lidia Pino a , Patrizia Frontera b,c , Marco Ferraro a , Vincenzo Antonucci a a CNR-ITAE “Nicola Giordano”, Via Salita S. Lucia sopra Contesse 5, 98126, Messina, Italy b Dept. of Civil Engineering, Energy, Environment and Materials (DICEAM), University “Mediterranea” of Reggio Calabria, Via Graziella, Feo di Vito, 89124, Reggio Calabria, Italy c National Interuniversity Consortium of Materials Science and Technology (INSTM), Via G. Giusti 9, 50121, Firenze, Italy ARTICLE INFO Keywords: CO 2 methanation Ni catalysts Gadolinia doped ceria Structured catalyst Solution combustion synthesis ABSTRACT The methanation of CO 2 via the Sabatier process is gaining interest for power-to-gas (P2G) application. In this work, CO 2 methanation activity and stability were investigated over Ni/GDC (gadolinium-doped-ceria) catalysts at atmospheric pressure varying reaction temperature (T SET = 300–600 °C) and space velocity (GHSV = 10,000–50,000 h -1 ). Powder catalysts with different Ni content (15–50 wt.%) were synthesized by the solution combustion synthesis (SCS). The same method was adopted to in situ deposit the Ni/GDC (50 wt.%Ni) coating layer on the cordierite monolith (500 cpsi). The catalysts were characterized by N 2 adsorption-deso- rption, X-ray diffraction (XRD), H 2 temperature programmed reduction (H 2 -TPR), CO 2 temperature programmed desorption (CO 2 -TPD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Temperature profiles along the structured catalytic bed were discussed to interpret the experimental results. Catalytic performance increased by increasing the Ni content due to enhanced metal-to-support interaction, basicity and oxygen vacancies. Uniform, thin and high-resistance catalytic layers were in situ deposited on the cordierite monoliths by the fully reproducible SCS method. Structured catalysts showed high methane pro- ductivity per unit weight of catalyst due to simultaneous low catalytic loading and high flow rate. Excellent stability was observed over 200 h of time-on-stream. The results reported in this manuscript pinpointed on the important aspects of realizing CO 2 methanation on structured catalysts, providing a platform for further opti- mization studies. 1. Introduction A successful transition towards a cleaner and more sustainable en- ergy system in 2050 requires large-scale implementation of sustainable and renewable energy source. In contrast with conventional energy sources, the intermittency and fluctuation of renewable energy make difficult its integration into the existing energy grid [1,2]. Recently, Power-to-Gas (P2G) technologies have been introduced with the aim to store the excess of non-programmable renewable energy. In particular, P2G technologies involve two stage: (i) conversion of electrical power to hydrogen via electrolysis and (ii) conversion of hydrogen to high- value chemicals or fuels thought reaction with CO 2 [3–5]. In this con- test, the production of Substitute Natural Gas (SNG) by CO 2 methana- tion, also called Sabatier reaction, proceeds according to [6,7]: CO 2 + 4H 2 ↔ CH 4 + 2H 2 O ΔH ° 298k = –165 kJ/mol It is a reaction of great technological and environmental potential, leading to (i) storage of excess H 2 generated from renewable energy, (ii) reduction of CO 2 emissions (greenhouse gas) from the atmosphere and (iii) production of SNG whose distribution infrastructures are readily available [8–10]. CO 2 methanation is a complex reaction because it is strongly exo- thermic and thermodynamically favored at low temperatures where kinetic rates are low [11]. Moreover, the high concentration of CO 2 involved results in large potential temperature increases and hot spot formation, lowering the yield and leading to catalyst deactivation by sintering and carbon deposition. For these reasons, the catalyst should be active and stable both at low and high temperature [12]. In the last three decades, several systems have been widely investigated as catalyst https://doi.org/10.1016/j.apcatb.2017.12.078 Received 24 October 2017; Received in revised form 20 December 2017; Accepted 31 December 2017 ⁎ Corresponding author. E-mail address: antonio.vita@itae.cnr.it (A. Vita). Applied Catalysis B: Environmental 226 (2018) 384–395 Available online 02 January 2018 0926-3373/ © 2018 Elsevier B.V. All rights reserved. T