Abstract
In this work, bimetallic catalysts (Pt-Ni/CeO2-Al2O3) in the form of powder and structured samples were employed for the oxidative steam reforming of fuel grade bioethanol. The stability performance of the above samples was investigated in a stainless steel tubular reactor at 500°C and 1 atm by feeding a commercial fuel grade ethanol stream with a H2O/C2H5OH = 4 and O2/C2H5OH = 0.5. Preliminarily, the ceria loading (between 25 and 45 wt%) as well as the Pt content (between 2 and 5 wt%) were optimized with respect to the washcoat (wc) content for the powder sample. Stability tests were carried out for 24 hours at 500°C and WHSV (Weight Hourly Space Velocity) = 12 h-1. The highest endurance performance was recorded over the 3Pt-10Ni/35CeO2/wc, which assured an ethanol conversion of almost 98% at the end of the test with a corresponding hydrogen yield of 50%. When the most promising formulation was transferred on a Ni-Fe substrate (made of an open cell foam), a clear improvement in the catalyst performance was recorded. In particular, the structured catalyst, able to assure a very good heat management within the catalytic bed as well as an improved mass transport, displayed a more stable behaviour compared to the corresponding powder, even in the presence of the typical bioethanol impurities; moreover, no significant formation of unwanted by-products (coke precursors) was observed during 24 hours of time-on- stream (TOS).
