n-BUTANE DEHYDROGENATION ON TRIMETALLIC CATALYSTS PtSnIn AND PtSnGa SUPPORTED ON SUPPORTS PREPARED BY WASHCOATING.

ADRIANA D. BALLARINI; PATRICIA D. ZGOLICZ; SONIA A. BOCANEGRA; OSVALDO A. SCELZA; SERGIO R. DE MIGUEL

Cancun

Congreso; XXV International Materials Research Congress; 2016

In this paper the catalytic performance of trimetallic catalysts supported on gamma-Al2O3, prepared by washcoating on spheres of alpha-Al2O3 (gamma-A-wc), in the n-butane dehydrogenation is studied. For this purpose, Pt, PtSnIn and PtSnGa catalysts were prepared. Besides, the effect of the of In (0.3 and 0.5 wt%) and Ga (0.18 and 0.3 wt%) addition to Pt(0.3 wt %)Sn(0.5wt%) catalyst on the activity and selectivity was analyzed. The catalysts characterization was carried out by using cyclohexane dehydrogenation (CHD) cyclopentane hydrogenolysis (CPH), temperature programmed reduction (TPR), scanning electronic microscopy (SEM) and XPS. Catalytic results show that those trimetallic catalysts have better performance than monometallic ones. The best catalysts were PtSnIn(0.5%) y PtSnGa(0.3%), those with the highest content of the third metal. These results are in agreement with those of characterization, which show important electronic and geometric (dilution and blocking) effects due to the addition of metallic promoters to Pt. Results of hydrogen chemisorptions and cyclopentane hydrogenolysis, showed that promoters atoms (Sn, In and Ga) produce geometric effects, dilution and blocking effects, on Pt atoms in PtSnIn(0.5)/gamma-A-wc and PtSnGa(0.3)/gamma-A-wc catalysts. PtSnIn catalysts would show a higher fraction of intermetallic alloys (much higher than PtSnGa) and a slightly better catalytic performance, which could be due to the different alloy concentrations in both catalysts. Xps results confirm the presence of surface metallic Pt(0), In(0) or Ga(0), Sn(II)/Sn(IV) species in a high concentration and minor amount of surface Sn(0), probably forming small quantities of alloy particles with Pt and Ma=In or Ga. The effect of the Sn, In or Ga addition to Pt observed during the initial steps of the reaction leads to the inhibition of the reactions which produce coke. Finally, the method of washcoating on gamma-alumina spherical nuclei alpha alumina seems to be a suitable method for preparing multimetal structured catalysts supports.