TY - GEN
T1 - Thermal stability of Pt nanoparticles supported on WOx/Al 2O3 for n-heptane hydroconversion
AU - Contreras, J. L.
AU - Fuentes, G. A.
AU - Salmones, J.
AU - Zeifert, B.
PY - 2010
Y1 - 2010
N2 - The thermal stabilization of γ-Al2O3 using W+6 ions has been found useful to the synthesis of Pt/Al 2O3 catalysts. The sequential impregnation method was used to study the effect of W6+ upon Pt/ γ-Al2O 3 reducibility, Pt dispersion, Raman spectroscopy and ç-heptane hydroconversion. The W/Pt atomic ratios varied from 3.28 to 75. We found that the W6+ ions delayed reduction of a fraction of Pt+4 atoms beyond 773 K. At the same time, W6+ inhibited sintering of the metallic crystallites once they were formed on the surface. For the sample with a W/Pt atomic ratio of 3.28, W6+ did not inhibit the H2 reduction of Pt oxides even below of 773 K, the Pt oxides were reduced completely, however, the Pt dispersion decreased for this sample with respect to the Pt/γ-Al2O3 catalyst. After reduction at 1073 K, sequential samples impregnating Pt on WOx/γ-Al 2O3 were more active and stable during n-heptane hydroconversion than monometallic Pt/γ-Al2O3 catalyst. Selectivities for dehydrocyclization, isomerization and Hydrocracking changed significantly when the W/Pt atomic ratio and reduction temperature increased. Initial and final reaction rates were more sensitive to reduction temperature. W6+ ions promoted high thermal stability of Pt crystallites when sequential catalysts were reduced at 1073 K and deactivation of bimetallic catalysts reduced at 773 K and 1073 K was less than the deactivation of Pt/Al2O3 catalyst.
AB - The thermal stabilization of γ-Al2O3 using W+6 ions has been found useful to the synthesis of Pt/Al 2O3 catalysts. The sequential impregnation method was used to study the effect of W6+ upon Pt/ γ-Al2O 3 reducibility, Pt dispersion, Raman spectroscopy and ç-heptane hydroconversion. The W/Pt atomic ratios varied from 3.28 to 75. We found that the W6+ ions delayed reduction of a fraction of Pt+4 atoms beyond 773 K. At the same time, W6+ inhibited sintering of the metallic crystallites once they were formed on the surface. For the sample with a W/Pt atomic ratio of 3.28, W6+ did not inhibit the H2 reduction of Pt oxides even below of 773 K, the Pt oxides were reduced completely, however, the Pt dispersion decreased for this sample with respect to the Pt/γ-Al2O3 catalyst. After reduction at 1073 K, sequential samples impregnating Pt on WOx/γ-Al 2O3 were more active and stable during n-heptane hydroconversion than monometallic Pt/γ-Al2O3 catalyst. Selectivities for dehydrocyclization, isomerization and Hydrocracking changed significantly when the W/Pt atomic ratio and reduction temperature increased. Initial and final reaction rates were more sensitive to reduction temperature. W6+ ions promoted high thermal stability of Pt crystallites when sequential catalysts were reduced at 1073 K and deactivation of bimetallic catalysts reduced at 773 K and 1073 K was less than the deactivation of Pt/Al2O3 catalyst.
UR - http://www.scopus.com/inward/record.url?scp=79952554583&partnerID=8YFLogxK
U2 - 10.1557/proc-1279-31
DO - 10.1557/proc-1279-31
M3 - Contribución a la conferencia
AN - SCOPUS:79952554583
SN - 9781605112565
T3 - Materials Research Society Symposium Proceedings
SP - 123
EP - 141
BT - New Catalytic Materials
PB - Materials Research Society
ER -