Abstract
The aim of the present work is to study the application of a fluidized bed reactor for oxidative steam reforming of ethanol (OESR) over a bimetallic 3wt% Pt-10wt% Ni/CeO2-SiO2 catalyst. In particular, the effect of cerium salt precursor (nitrate (N), ammonium nitrate (AN) and acetylacetonate (AC)) on catalyst activity and stability was investigated. Three catalysts were synthetized. In all cases, the support was composed of a CeO2-SiO2 mixed oxide and the ceria content for all the catalysts was fixed to 30 wt%. The tests were carried out at a steam to ethanol ratio (f.r.) of 4 and oxygen to ethanol ratio (o.r.) of 0.5; temperature was fixed to 500°C and the weigh hourly space velocity (WHSV) to 12.3 h-1. All the samples displayed a partial deactivation with time-on-stream and ethanol was completely converted only for few hours. The initial H2 yield was very close to the predicted thermodynamic value (41.5%) and a gradual yield lowering was observed over the three catalysts. However, after 80 h of test, all the samples reached a plateau condition, with no more variation in selectivity. It is worthwhile noting that, for the sample AC, the final conversion was attested to 75%, while the other two catalysts displayed a similar behaviour with plateau conversion of almost 60%. In addition, a higher H2 yield (20%) was recorded after 100 h of test for the sample AC and the carbon formation rate measured after the test on the latter catalyst was almost 1 half of the values found for the catalysts N and AN: in the case of acetylacetonate, the organic group of the salt probably assures a templanting effect, which protects ceria molecules, improving their dispersion and increasing catalyst activity towards both reforming and carbon gasification reactions.
