CO2 Methanation over Rh/CeO2 Studied with Infrared Modulation Excitation Spectroscopy and Phase Sensitive Detection

Abstract

Methane is a well-established fuel molecule whose production from CO 2 through methanation garners increasing interest as an energy storage solution. While often produced with Ni based catalysts, other metals are of interest thanks to higher robustness and activity-selectivity numbers. The Rh/CeO 2 catalyst has shown appreciable properties for CO 2 methanation and its structural dynamics has been studied in situ. However, the reaction pathway is unknown. Here, we present infrared modulation excitation spectroscopy measurements with phase sensitive detection of a Rh/CeO 2 catalyst adsorbate composition during H 2 pulsing (0–2 vol.%) to a constant CO 2 (0.5 vol.%) feed. Various carbonyl (CO) and carbonate (b-CO 3 /p-CO 3 ) ad-species clearly respond to the hydrogen stimulus, making them potential reaction intermediates. The different CO ad-species are likely intermediates for product CO and CH 4 but their individual contributions to the respective formations are not unambiguously ascertained. As for the carbonate dynamics, it might be linked to the reduction/oxidation of the CeO 2 surface upon H 2 pulsing. Formate (HCOO) ad-species are clearly visible but appear to be, if not spectators, linked to slow side reactions possibly also affected by CeO 2 redox processes.

Elucidating Active CO–Au Species on Au/CeO2(111): A Combined Modulation Excitation DRIFTS and Density Functional Theory Study

“…particle shape and degree of reduction. Via an overlap, the neighboring signals or even the background might influence the regarded signal according to the relative intensity of it and the overlapping contribution, thus a mixing of time values occurs, as has been already described elsewhere [38]. Therefore it might as well be the case that these overlap effects lead to different time values of the same species on ceria sheets and polyhedra.…”

Role of ZrO2 and CeO2 support on the In2O3 catalyst activity for CO2 hydrogenation

“…6). [60] In addition to this, various types of O-H bands between 3400-3700 cm -1 , which are related to bridge as well as hydrogen-bonded OH groups, were observed over In 13 /ZrO 2 (Figure 7a). While over In 13 /CeO 2 , only two OH bands related to bridged species on Ce 3+ and Ce 4+ appeared at low temperatures which further disappeared at higher temperatures and only one OH band remained over the catalyst surface which is assigned to hydrogenbonded OH groups (Figure 7b).…”

Unraveling the Active Vanadium Sites and Adsorbate Dynamics in VOx/CeO2 Oxidation Catalysts Using Transient IR Spectroscopy

“…In fact, besides significant noise reduction, such an approach allows discrimination between active and spectator species and, thus, a focus on the crucial aspects of the mechanism. In heterogeneous catalysis, MES has been mostly used to study reactions of small molecules, e.g., CO oxidation, − NH 3 –SCR (selective catalytic reduction), − and CO 2 activation, − but to the best of our knowledge, there has been no application in the context of the economically important field of alkane oxidation catalysis.…”