Abstract
Positive environmental and technological contexts make dry methane reforming (DMR) an extensively studied reaction. During this process two main greenhouse gases CH4and CO2can be simultaneously converted into syngas – a mixture of CO and H2. Supported-nickel is one of the most frequently applied DMR catalysts. Their activity depends mainly on Ni concentration, kind of its precursor and a deposition method. As DMR is a demanding high-temperature reaction, it requires not only an active but first a very stable catalyst. Structural, textural and functional properties of such support remain thus of crucial efficiency. Main aim of this work was to elucidate how the synthesis of CeO2-ZrO2support obtained by supercritical fluid method (i.e.at temperature of 400°C under a pressure of 25 MPa), can influence the properties of Ni-based DMR catalysts. The supports of various compositions (CeO2content from 100 to 0 %), subsequently calcined at 800°C for 6h in air have been analyzed. Nickel was deposited from nitrate(V) precursor via classical wet impregnation. The final catalysts have been characterized structurally (XRD, RS), texturally (BET, SEM) and functionally (UV/Vis-DR, XPS). Catalytic tests in dry methane reforming reaction have been performed to determine activity and stability of the synthesized samples.
Highlights
Nowadays ceria-zirconia binary oxides belong to relatively frequently used catalytic supports for both metals and metal oxides deposited on their surfaces as catalytically active phases
It was quite interesting that for the samples analyzed after dry methane reforming (DMR) test, the trend related to the intensity ratio of two types of the observed oxygen species, contributing to O 1s window and discussed above, was opposite to that described for samples before catalytic test – defect oxygen predominated the X-ray photoelectron spectroscopy (XPS) spectra
It was confirmed within the current work, that the presence of CexZr1xO2 solid solutions was characteristic of the studied binary supports
Summary
Nowadays ceria-zirconia binary oxides belong to relatively frequently used catalytic supports for both metals and metal oxides deposited on their surfaces as catalytically active phases. It was reported by many authors that these binary oxides obtained via conventional methods from aqueous solutions of nitrate or chloride precursors of ZrO2 tend to loose their homogeneity under reducing DMR reactional conditions undergoing a progressive segregation [12, 15] This effect is directly linked with the characteristic speciation of Zr(IV) ions in the corresponding aqueous solutions of ZrO2 precursor, where zirconium component occurs in a form of hydroxo-aqua [Zr(OH)2 ● 4H2O]48+ complexes of tetrahedral coordination [16]. Such coordination can be partially stabilized within the final CeO2-ZrO2 binary system, facilitating its hightemperature evolution leading to a structural instability and a stepwise segregation. In the figures below the selected results for NiOx/Ce0.5Zr0.5O2 catalyst - the most active in DMR, are presented
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
