Carbon dioxide reforming of methane over bimetallic catalysts of Pt-Ru/γ-Al₂O₃ for thermochemical energy storage

Abstract

The reaction of CO₂ reforming of CH₄ has been investigated with γ-Al₂O₃-supported platinum and ruthenium bimetallic catalysts, with the specific purpose of thermochemical energy storage. The catalysts were prepared by using the wetness impregnation method. The prepared catalysts were characterized by a series of physico-chemical characterization techniques such as BET surface area, thermo-gravimetric (TG), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). In addition, the amount of carbon deposits on the surface of the catalysts and the type of the carbonaceous species were discussed by TG. It was found that the bimetallic Pt-Ru/γ-Al₂O₃ catalysts exhibit both superior catalytic activity and remarkable stability by comparison of monometallic catalysts. During the 500 h stability test, the bimetallic catalyst showed a good performance at 800 °C in CO₂ reforming of CH₄, exhibiting an excellent anti-carbon performance with the mass loss of less than 8.5%. The results also indicate that CO₂ and CH₄ have quite stable conversions of 96.0 % and 94.0 %, respectively. Also, the selectivity of the catalysts is excellent with the products ratio of CO/H₂ maintaining at 1.02. Furthermore, it was found in TEM images that the active carbonaceous species were formed during the catalytic reaction, and well-distributed dot-shaped metallic particles with a relatively uniform size of about 3 nm as well as amorphous carbon structures were observed. Combined with BET, TG, TEM tests, it is concluded that the selected bimetallic catalysts can work continuously in a stable state at the high temperature, which has a potential to be utilized for the closed-loop cycle of the solar thermochemical energy storage in future industry applications.

Keywords

carbon dioxide reforming of methane / Pt-Ru/γ-Al₂O₃ catalysts / long-term stability / thermochemical energy storage

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