Dry Reforming of Methane: Catalytic Performance and Stability of Ir Catalysts Supported on γ-Al2O3, Zr0.92Y0.08O2−δ (YSZ) or Ce0.9Gd0.1O2−δ (GDC) Supports

Abstract

The impact of the support on the Ir-catalyzed dry (CO 2 ) reforming of methane (DRM) reaction is explored in the present study. With this aim, supported iridium catalysts Ir/c-Al 2 O 3 , Ir/YSZ and Ir/GDC with 1 wt% iridium loading, using c-Al 2 O 3 , 8 mol% Y 2 O 3 stabilized ZrO 2 (YSZ: Zr 0.92 Y 0.08 O 2-d ) and 10 mol% Gd 2 O 3 doped CeO 2 (GDC: Ce 0.9 Gd 0.1 O 2-d ) as supports were comparatively studied in the temperature range of 400-850°C. The feasibility of tuning the catalytic performance and/or stability of the Ir active phase during DRM reaction, via support-induced interactions, was investigated. All catalysts were found to be extremely active and stable over time on stream. No significant effects induced by the support were observed at the high operating temperature of DRM. However, opposite to Ir/cAl 2 O 3 and Ir/YSZ samples, Ir/GDC provides the benefit to be stable in oxidation steps and/or oxidation-reduction cycles. This is of significant practical importance since such treatment procedures are often used in practice for catalysts regeneration. Besides catalytic performance measurements, extended hydrogen temperature-programmed reduction experiments, supported further by transmission electron microscopy characterization studies were carried out in order to reveal the impact of the support on the aforementioned stability and its origin.

Effect of support oxygen storage capacity on the catalytic performance of Rh nanoparticles for CO2 reforming of methane

“…For example, CexZr1-xO2-δ composites, which are widely used in three-way catalytic chemistry due to their high oxygen storage capacity (OSC) [36][37][38], improved both the efficiency and long term stability of Ni catalysts in DRM [20,27,34,35]. Noble metal-based catalysts exhibit comparable DRM activity to Ni formulations, but also greater resistance to carbon deposition, [3,[9][10][11][39][40][41][42][43][44][45][46][47], which offsets their high cost for potential large-scale application.…”

“…They are nevertheless effective because they are continuously replenished by labile O 2species provided by the support. At very high temperatures, where the lifetime of O δspecies is significantly shortened[40], their promotional effect is correspondingly diminished. The Arrhenius diagrams inFig.…”

Biogas Management: Advanced Utilization for Production of Renewable Energy and Added-value Chemicals

“…Methane (external) reforming (route#1-1, Figure 4) is a well-established technology for synthesis gas (H 2 +CO) or H 2 production (e.g., Ashcroft et al, 1991;Bradford and Vannice, 1999;Verykios, 2003;Papadopoulou et al, 2012;Yentekakis et al, 2015). Practically, any composition (poor, equimolar, or rich in CH 4 ) of the purified biogas itself is a suitable feed for the dry reforming of methane (DRM) process, which occurs through the reaction (R18):…”

The Effect of WO3 Modification of ZrO2 Support on the Ni-Catalyzed Dry Reforming of Biogas Reaction for Syngas Production

“…In theory, coke deposition can be avoided by: (i) altering the electronic properties of metal-support interactions, (ii) influencing the size of metallic particles and, (iii) improving the oxygen storage capacity and mobility within supporting material (Roh et al, 2006;Kumar et al, 2007;Chen et al, 2008;Goula et al, 2014;Yentekakis et al, 2015Yentekakis et al, , 2016Han et al, 2017). 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).…”