“…Thus, the attempts that have been undertaken to improve the stability of DRM nickel catalysts have focused on the use of different oxides as supports (e.g., Al 2 O 3 , SiO 2 , La 2 O 3 , CeO 2 , ZrO 2 ) (Pompeo et al, 2007;Bereketidou and Goula, 2012;Li et al, 2016) or the use of a variety of dopants that include transition metals (e.g., Fe, Co, Sn) (Ay and Uner, 2015;Theofanidis et al, 2015;Zhao et al, 2016), noble metals (e.g., Ag, Pt, Pd, Ir) Yentekakis et al, 2015;Yu et al, 2015), lanthanide metals (e.g., La, Ce, Pr) (Goula et al, 2016a;Vasiliades et al, 2016;Xiang et al, 2016) and alkaline earth metals (e.g., Sr, Ca, Ba) (Bellido et al, 2009;Sutthiumporn and Kawi, 2011). Although ZrO 2 is an oxide with a relatively low surface area, its notable thermal stability, strength and toughness, as well as, the fact that it is an acid-basic bi-functional oxide (as it contains both basic and acidic properties over its surface that have the capacity to work either independently or in cooperation), which has redox functions, makes it attractive for use in reforming reactions (Sarkar et al, 2007;Goula et al, 2017;Charisiou et al, in press). Shiju et al (2009) suggested that tungstated zirconia possesses mainly acid sites, but their number and strength is strongly depended on the preparation conditions chosen for the support and its calcination temperature.…”