Effect of the Synthesis Method of MgAl2O4 and of Sn and Pb Addition to

SONIA BOCANEGRA; MARÍA JULIA YAÑEZ; OSVALDO SCELZA; SERGIO DE MIGUEL

INDUSTRIAL & ENGINEERING CHEMICAL RESEARCH

American Chemical Society

Año: 2010 vol. 49 p. 4044 - 4054

0888-5885

The MgAl2O4 spinels, synthesized by using two different methods (ceramic and co-precipitation), show very low acidity and good interaction with the metallic phase, these properties being suitable for the use of this material as supports. However, the MgAl2O4cer displays higher acidity than the MgAl2O4cop which seems to influence in the metal-support interaction, since Pt/MgAl2O4cer catalyst shows higher metallic dispersion, lower metal particle sizes and better catalytic behavior than the Pt/MgAl2O4cop one. The Sn addition to Pt supported on MgAl2O4 improves the performance in the dehydrogenation process, increasing the activity, stability and selectivity to butenes. This behavior is due to the presence of important Pt-Sn interactions,  mainly in bimetallic catalysts supported on MgAl2O4cer. On the other hand, the Pb addition to monometallic catalysts does not enhance the catalytic performance in dehydrogenation. This behavior is in agreement with the characterization results of metallic phase that indicate important blocking effects in PtPb/MgAl2O4cop catalysts, and segregation effects in  PtPb/MgAl2O4cer. In conclusion, the ceramic method of MgAl2O4 preparation provides the best support for metallic catalysts in n-butane dehydrogenation reaction, and the PtSn(0.3)/MgAl2O4cer catalyst was the one that showed the best catalytic performance in this reaction.