Comparisons of Pt catalysts supported on active carbon, carbon molecular sieve, carbon nanotubes and graphite for HI decomposition at different temperature

A series of Pt catalysts supported on activated carbon (AC), carbon molecular sieve (CMS), carbon nanotubes (CNT) and graphite (GR) were prepared by the impregnation method. Their catalytic performances in HI decomposition were evaluated in a fixed bed reactor at temperatures ranging from 400 to 550 °C under atmospheric pressure. The different Pt catalysts before and after HI decomposition at different temperature were characterized by BET, XRD and TEM, respectively. The results of the activity evaluation indicated that the activity order of different Pt catalysts changed significantly with the variation of reaction temperature. At 400 °C, different supported Pt catalysts activities decreased in order of Pt/CMS > Pt/AC > Pt/CNT > Pt/GR. At 450 °C, the activities of different Pt catalysts followed the order of Pt/AC ≈ Pt/CNT > Pt/CMS > Pt/GR. At 500 and 550 °C, the Pt/CNT showed the optimum activity and stability during HI decomposition, which could be attributed to the high dispersion of Pt particles and the special microstructure of CNT. The XRD and TEM results illustrated that the Pt particle size or Pt dispersion in different supported Pt catalysts showed different sensitivity to the reaction temperature.