In situ NAP-XPS spectroscopy during methane dry reforming on ZrO₂/Pt(1 1 1) inverse model catalyst

Abstract

Due to the need of sustainable energy sources, methane dry reforming is a useful reaction for conversion of the greenhouse gases CH and CO to synthesis gas (CO + H). Syngas is the basis for a wide range of commodity chemicals and can be utilized for fuel production via Fischer-Tropsch synthesis. The current study focuses on spectroscopic investigations of the surface and reaction properties of a ZrO/Pt inverse model catalyst, i.e. ZrO particles (islands) grown on a Pt(1 1 1) single crystal, with emphasis on in situ near ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) during MDR reaction. In comparison to technological systems, model catalysts facilitate characterization of the surface (oxidation) state, surface adsorbates, and the role of the metal-support interface. Using XPS and infrared reflection absorption spectroscopy we demonstrated that under reducing conditions (UHV or CH) the ZrO particles transformed to an ultrathin ZrO film that started to cover (wet) the Pt surface in an SMSI-like fashion, paralleled by a decrease in surface/interface oxygen. In contrast, (more oxidizing) dry reforming conditions with a 1:1 ratio of CH and CO were stabilizing the ZrO particles on the model catalyst surface (or were even reversing the strong metal support interaction (SMSI) effect), as revealed by in situ XPS. Carbon deposits resulting from CH dissociation were easily removed by CO or by switching to dry reforming conditions (673-873 K). Thus, at these temperatures the active Pt surface remained free of carbon deposits, also preserving the ZrO/Pt interface.

Carbide-Modified Pd on ZrO2 as Active Phase for CO2-Reforming of Methane—A Model Phase Boundary Approach

“…From a fundamental scientific viewpoint, a group of highly active catalysts on noble metal basis exhibiting enhanced coking resilience deserve particular attention [8,9,[11][12][13][14][15][16][17]. In a recent near-ambient-pressure in-situ X-ray photoelectron spectroscopy (NAP-XPS) study of our group, the particular anti-coking and carbon-converting role of the Pd/ZrO 2 phase boundary was highlighted [18].…”

Metal–Support Interactions and C1 Chemistry: Transforming Pt-CeO2 into a Highly Active and Stable Catalyst for the Conversion of Carbon Dioxide and Methane

“…In general, when optimizing the performance Pt MDR catalysts scientist has followed two different approaches: changing the oxide support (Al2O3, MgO, CeO2, ZrO2, CeO2-ZrO2) and alloying Pt with a second metal (Fe, Co, Ni, Cu). 6,[25][26][27][28][29][53][54][55] Our results show the important role that ceria plays as an active support/participant in the MDR process. It is superior with respect to Al2O3 and MgO because these oxides usually do not interact strongly with supported metals like ceria does.…”

Comparison of novel Ni doped exsolution perovskites as methane dry reforming catalysts

“…However, MDR has a significantly lower energy consumption compared to other methane reforming processes and a product ratio suitable for direct conversion of the formed synthesis gas into further valuable products such as long chain hydrocarbons (via the Fischer-Tropsch process) or methanol [1]. Dry reforming can also easily be extended from methane to other hydrocarbons, making the reaction very important for the processing of natural gas resources or renewable feedstocks such as biogas [2].…”