Ceramic foams coated with Pt-Ni/CeO2-ZrO2 for bioethanol steam reforming

摘要

The catalytic activity of bimetallic Pt-Ni/CeO2-ZrO2 powders and foams, with a silicon carbide carrier and containing silica or boehmite as binder, was investigated for ethanol steam reforming in the low temperature range (400-500 degrees C). A parametric experimental study was preliminary performed to analyze the effect of different operative conditions (temperature, water/ethanol ratio and contact time) on coke selectivity: low temperatures and space velocities as well as high water contents in the feeding stream minimized carbon deposits formation and reactor plugging. Moreover, once analyzed the individual influence of C2H4O, C3H7OH, C4H9OH and C5H11OH, selected among the main bioethanol contaminants, on catalyst deactivation, a model mixture, containing 1% mol of all the impurities, was fed to the reformer at 15,000 h(-1), T = 450 degrees C and water/ethanol ratio equal to 6. In order to test catalytic behavior in more stressful conditions, contact time was decreased and the stability of powder and foam catalysts was investigated at 50,000 h(-1). Despite very similar H-2 selectivities were recorded, the structured samples, containing boehmite as binder, showed the most interesting catalytic performance, as total ethanol conversion was assured for more than 1 day of time-on-stream. Foams geometry, in fact, enhanced coke gasification reactions, limiting, at the same time, plugging phenomena. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.