Highly sulfur-tolerant Pt/Ce_0.8Gd_0.2O_1.9 catalyst for steam reforming of liquid hydrocarbons in fuel cell applications

A sulfur-tolerant Pt catalyst has been developed for fuel processors being developed for use with fuel cells, using a fluorite-type Ce_0.8Gd_0.2O_1.9 support. The catalyst calcination temperature is crucial to ensure the maintenance of sulfur tolerance. The catalyst calcined at 800 °C retained its activity and selectivity for entire 100-h test period in the steam reforming of iso-octane with ≥300 μg/g of sulfur, whereas the catalyst calcined at 600 °C obviously lost activity in this course. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) for CO and CO/H₂S adsorption was performed to characterize the nature of the Pt sites and to evaluate their ability to tolerate sulfur. Strongly electron-deficient Pt sites, evidenced by a CO adsorption band at ν_max 2104-2108 cm^-1, were immune to sulfur poisoning and were uniformly formed with the calcination at 800 °C. In addition, thiophene sulfur was completely converted into H₂S and likely complied with a redox mechanism.