INCAPE   05401
INSTITUTO DE INVESTIGACIONES EN CATALISIS Y PETROQUIMICA "ING. JOSE MIGUEL PARERA"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Pt-Ge catalysts supported on functionalized granular carbon and prepared by conventional impregnation and control surface reaction for the citral hydrogenation
Autor/es:
JULIETA VILELLA, IRINA BORBÁTH, FERENC SOMODI; JOSZEF L. MARGITFALVI, SERGIO R. DE MIGUEL, O. SCELZA
Lugar:
Porto de Galinhas (Brasil)
Reunión:
Congreso; 14 Congresso Brasileiro de Catalise; 2007
Resumen:
The liquid-phase citral hydrogenation carried out at 70ºC and atmospheric pressure over PtGe catalysts supported on activated carbon powder was investigated. Two series of PtGe catalysts supported on carbon purified and then functionalized with nitric acid (C-PN) were prepared. One series by conventional successive impregnation (CI) with H2PtCl6 and GeCl4 and another series was prepared by controlled surface reaction (CSR). The performance of all these catalysts in the citral hydrogenation was related with the characteristics of the metallic phase, analyzed by test reactions (cyclohexane dehydrogenation and cyclopentane hydrogenolysis) and H2 chemisorption in order to postulate the models of the metallic surface. Results showed that in catalysts prepared by CI, Ge was located mainly on the support and it does not improve in an important way either the activity or the selectivity to unsaturated alcohols. CSR catalysts show much better activities and selectivities to unsaturated alcohols, nerol and geraniol (UA). It is needed a large concentration of Ge to polarize the carbonyl group in case of CI catalysts probably because Ge would be located mainly over the support, on the surroundings of the Pt particles and small quantities would be deposited over the Pt particles. Nevertheless, in CSR catalysts, Ge moieties would polarize the carbonyl group since they would be placed near PtGe nanoclusters, thus giving good selectivity to unsaturated alcohols. Results showed that in catalysts prepared by CI, Ge was located mainly on the support and it does not improve in an important way either the activity or the selectivity to unsaturated alcohols. CSR catalysts show much better activities and selectivities to unsaturated alcohols, nerol and geraniol (UA). It is needed a large concentration of Ge to polarize the carbonyl group in case of CI catalysts probably because Ge would be located mainly over the support, on the surroundings of the Pt particles and small quantities would be deposited over the Pt particles. Nevertheless, in CSR catalysts, Ge moieties would polarize the carbonyl group since they would be placed near PtGe nanoclusters, thus giving good selectivity to unsaturated alcohols.