Abstract
Developing a catalyst with high SO2 and H2O resistance to achieve high-performance CO oxidation for specific industrial applications is highly desirable. Here, three catalysts were prepared using cerium titanium composite oxide (CeTi), molybdophosphate with Keggin structure-modified CeTi (Keg-CeTi), and molybdophosphate without Keggin structure-modified CeTi (MoP-CeTi) as supports, and their sulfur and water resistance in CO oxidation were tested. The characterization of XRD, BET, SO2/H2O-DRIFTS, XPS, TEM, SEM, NH3/SO2-TPD, H2-TPR, and ICP techniques revealed that the high SO2 and H2O resistance of Pt/Keg-CeTi in CO oxidation was related to its stronger surface acidity, better reduction of surface cerium and molybdenum species, and lower SO2 adsorption and transformation compared to Pt/CeTi and Pt/MoP-CeTi.
Highlights
Carbon monoxide (CO) is one of the major air pollutants mainly originating from the incomplete combustion of fossil fuels or from industrial production.It affects the atmospheric chemistry and climate and the health of human beings and animals [1]
The gold catalysts and a few transition metal oxide catalysts commonly show a higher performance in CO oxidation at low temperature compared to the PGM ones, but the two former types of catalysts suffer from the easy deactivation in the presence of sulfur and moisture
In addition,no nosimilar peak that could be assigned to metallic platinum or its oxides catalyst, indicating the destruction of the Keggin structure after the high-temperature was observed in the X-ray diffraction (XRD) curves of the three samples, implying the high dispersion of Pt
Summary
Carbon monoxide (CO) is one of the major air pollutants mainly originating from the incomplete combustion of fossil fuels (e.g., coal and oil) or from industrial production. The PGM catalysts, platinum, have been investigated for nearly a century since Langmuir’s pioneering work [22], which showed high activities for CO oxidation in the temperature range of 150 to 250 ◦ C with high resistance to sintering and water tolerance [23,24]. Pt-DG possessed a higher sulfur and water resistance due to the fact that carbon divacancy makes Pt less attractive toward SO2 and H2 O molecules compared to Pt-SG, revealing the effect of the support structure to catalyst performance. Yoshida [36] reported that the Keggin-type polyoxometalate-supported gold catalyst exhibited a high catalytic activity for CO oxidation at low temperature and extremely high stability. The above results inspired us to investigate the promotion of the Keggin structure to the sulfur and water resistance of Pt/CeTi catalysts for CO oxidation. Pt/MoP-CeTi catalysts, revealing the remarkable promotion effect of the Keggin structure
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