Identification of Highly Selective Surface Pathways for Methane Dry Reforming Using Mechanochemical Synthesis of Pd–CeO₂

Abstract

The methane dry reforming (DRM) reaction mechanism was explored via mechanochemically prepared Pd/CeO2 catalysts (PdAcCeO2M), which yield unique Pd–Ce interfaces, where PdAcCeO2M has a distinct reaction mechanism and higher reactivity for DRM relative to traditionally synthesized impregnated Pd/CeO2 (PdCeO2IW). In situ characterization and density functional theory calculations revealed that the enhanced chemistry of PdAcCeO2M can be attributed to the presence of a carbon-modified Pd0 and Ce4+/3+ surface arrangement, where distinct Pd–CO intermediate species and strong Pd–CeO2 interactions are activated and sustained exclusively under reaction conditions. This unique arrangement leads to highly selective and distinct surface reaction pathways that prefer the direct oxidation of CH x to CO, identified on PdAcCeO2M using isotope labeled diffuse reflectance infrared Fourier transform spectroscopy and highlighting linear Pd–CO species bound on metallic and C-modified Pd, leading to adsorbed HCOO [1595 cm–1] species as key DRM intermediates, stemming from associative CO2 reduction. The milled materials contrast strikingly with surface processes observed on IW samples (PdCeO2IW) where the competing reverse water gas shift reaction predominates.

Photocatalytic C–N coupling towards urea synthesis with a palladium-supported CeO2 catalyst

“…89-4897) emerged in 12% Pd–CeO 2 and 16% Pd–CeO 2 due to the agglomeration of Pd species. 36 Besides, the XRD patterns of CeO 2 doped with other metals are shown in Fig. S3 †…”

Deactivation Mechanism and Anti-Deactivation Measures of Metal Catalyst in the Dry Reforming of Methane: A Review

“…In addition, the presence of CZ in the support helps to keep Rh in the metallic state and minimize carbon deposition under the reaction conditions. Jiménez et al [63] prepared a Pd/CeO 2 (PdAcCeO 2 M) catalyst using mechanical force chemistry, which exhibited a unique reaction mechanism and higher DRM reactivity and resistance to carbon deposition compared to Pd/CeO 2 (PdCeO 2 IW) catalysts synthesized via conventional impregnation. It was found that the enhanced chemistry of PdAcCeO 2 M can be attributed to the presence of carbon-modified Pd 0 and Ce 4+/3+ surface arrangements, where the unique Pd-CO intermediate species and strong Pd-CeO 2 interactions are fully activated and sustained under the reaction conditions.…”

Noble Metals in Recent Developments of Heterogeneous Catalysts for CO2 Conversion Processes

“…Recent studies by Jiménez et al [274] and Shen et al [245] have shed light on the potential benefits of using Pd and Pt supported over CeO 2 , respectively, using different synthesis methods. Jiménez et al [274] presented an interesting study with Pd supported over CeO 2 prepared via a mechanochemical synthesis and compared to a traditional incipient wetness impregnation synthesis. They found that the mechanochemically prepared Pd/CeO 2 catalysts presented unique PdÀ Ce interfaces, which led to a distinct reaction mechanism and higher reactivity for DRM (323 μ molH2 .g cat À 1 •s À 1 ;500 μmol CO .g cat À 1 •s À 1 ).…”

“…The synthesis method is also an effective strategy to enhance catalyst activity for DRM. Recent studies by Jiménez et al [274] and Shen et al [245] have shed light on the potential benefits of using Pd and Pt supported over CeO 2 , respectively, using different synthesis methods. Jiménez et al [274] presented an interesting study with Pd supported over CeO 2 prepared via a mechanochemical synthesis and compared to a traditional incipient wetness impregnation synthesis.…”