Influence of Na content on the catalytic properties of Pt-Ir/Al2O3catalysts for selective ring opening of decalin

MARIA ANA VICERICH; MARCELO OPORTUS; VIVIANA M. BENITEZ; PATRICIO REYES; CARLOS L. PIECK

APPLIED CATALYSIS A-GENERAL

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2014 vol. 480 p. 42 - 49

0926-860X

tThe influence of the Na addition on Pt-Ir/Al2O3on the reaction of selective ring opening of decalin andmethyl cyclopentane was studied. The catalysts were evaluated by means of TPR, pyridine TPD, TEM, FTIR-CO and by the reaction tests of cyclohexane dehydrogenation, hydrogenolysis of cyclopentane, selectivering opening of decalin and methyl cyclopentane. It was found that Na strongly decreases the acidity andinfluences the metal properties of Pt-Ir/Al2O3catalysts. The interaction between Pt and Ir is increasedby the presence of Na, with larger metal crystals being obtained on the support modified by Na. As aconsequence, the catalytic properties are also modified and the CP/CH ratio (parameter of demanding/notdemanding reaction) is increased with sodium concentration. In the case of MCP reaction, Na stronglydecreases the aromatic and n-C6formation and favors the selective reaction mechanism, thus favoring theformation of 2MP and 3MP. For the decalin reaction, it was found that the yield to the dehydrogenatedproduct of the catalysts supported on Al2O3-Na is lower than that of the free Na-alumina supportedcatalyst, whereas the opposite occurs with the yield to C1due to the higher hydrogenolytic and lowerdehydrogenation activity of the catalysts with Na. The yield to ring contraction (RC) products is higheron the catalyst without Na due to the higher acidity which favors the ring contraction reaction and thelower metallic activity; thus, the transformation of the RC product to ring opening products is decreased.