Bioethanol/glycerol mixture steam reforming over Pt and PtNi supported on lanthana or ceria doped alumina catalysts

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• 作者：M. El Doukkali ; ^{mohamed.eldoukkali@ehu.es} ; A. Iriondo ; P.L. Arias ; J.F. Cambra ; I. Gandarias ; V.L. Barrio
• 关键词：Ethanol/glycerol mixtures ; Catalytic steam reforming ; Hydrogen ; Platinum-nickel catalysts ; Alumina&ndash ; lanthana&ndash ; ceria ; Coke formation
• 刊名：International Journal of Hydrogen Energy
• 出版年：2012
• 期刊代码：42_03603199
• 类别：ch
• 出版时间：May, 2012
• 卷：37
• 期：10
• 页码：8298-8309
• 文件大小：1536 K

摘要

The catalytic activity of Pt and PtNi catalysts supported on 纬-Al₂O₃ modified by La and Ce oxides was investigated in the steam reforming of ethanol/glycerol mixtures. In general, all the catalysts fully converted the glycerol at the temperatures tested. However, the conversion of ethanol depended on the reaction temperature and catalyst type. The conversion into gaseous products operating at 500聽掳C and 450聽掳C was 100%using the most active catalysts (PtNiAl6La and PtNiAl10Ce). These two bimetallic catalysts gave H₂ yields close to those predicted by thermodynamic equilibrium at these temperatures. However, when the reaction temperature was lowered to 400聽掳C, these catalytic systems and the PtNiAl one recorded a significant decrease in ethanol conversion and H₂ yield, which moved away from the thermodynamic equilibrium value. This deviation was due to intermediate liquid products (acetaldehyde, acrolein, etc.) not being further reformed and the formation of other gaseous ones (light alkanes and ethylene). PtNiAl10Ce catalyst presented the highest conversion into gas at 400聽掳C, resulting in the largest H₂ yield, followed by PtNiAl6La and PtNiAl catalysts. This order is in agreement with the Ni/Al surface atomic ratio measured by XPS technique in reduced samples. However, filamentous carbon nanotubes were detected but this carbon type maintained the active sites accessible for reactants, since TEM and TGA results showed that the density of this carbon was lower for PtNiAl₁₀Ce catalyst. Pt catalysts presented lower activity than PtNi catalysts possibly due to the formation of carbon nanotubes, which covered some metallic active sites.