Influence of Support Acidity and Ir Content on the Selective Ring Opening of Decalin over Ir/SiO 2 –Al 2 O 3

D?IPPOLITO, SILVANA A.; BALLARINI, ADRIANA D.; PIECK, CARLOS L.

ENERGY & FUELS (PRINT)

AMER CHEMICAL SOC

Año: 2017 vol. 31 p. 5461 - 5471

0887-0624

The influence of the addition of HCl and Ir (1 wt %) to different SiO2−Al2O3 supports of varying silica contentwas studied in the reaction of selective ring opening of decalin. The addition of HCl to silica−alumina supports containing 70and 80 wt % SiO2 was found to have little influence in the distribution of reaction products compared to the calcined supports.The incorporation of Ir to the silica−alumina catalysts has a beneficial effect, increasing the decalin conversion, being this effectmore noticeable in the low acidity supports, i.e., those containing 30−40 wt % SiO2. The iridium-containing materials display thehighest yield of cracking products, ring opening products, and ring contraction products. Increasing the reaction temperaturepromotes cracking and dehydrogenation but markedly decreases the selectivity to ring contraction products. At 350 °C a slightdecrease in selectivity to ring opening products occurs, though the overall increase in conversion results in an increased yield ofthese products. An optimum ratio between the acid sites and metal activity that favors the formation of ring opening productswas found. At lower acid sites/metal activity ratios the isomerization reaction which leads to C5 cycle isomers is low, and ringopening by hydrogenolysis is limited as a consequence. On the other hand, at high acid sites/metal activity ratios the crackingreactions are favored, decreasing the yield of RO products.