1 research outputs found
Influence of Support Acidity and Ir Content on the Selective Ring Opening of Decalin over Ir/SiO<sub>2</sub>–Al<sub>2</sub>O<sub>3</sub>
The
influence of the addition of HCl and Ir (1 wt %) to different
SiO<sub>2</sub>–Al<sub>2</sub>O<sub>3</sub> supports of varying
silica content was studied in the reaction of selective ring opening
of decalin. The addition of HCl to silica–alumina supports
containing 70 and 80 wt % SiO<sub>2</sub> 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 effect more noticeable in the low acidity supports, i.e.,
those containing 30–40 wt % SiO<sub>2</sub>. The iridium-containing
materials display the highest yield of cracking products, ring opening
products, and ring contraction products. Increasing the reaction temperature
promotes cracking and dehydrogenation but markedly decreases the selectivity
to ring contraction products. At 350 °C a slight decrease in
selectivity to ring opening products occurs, though the overall increase
in conversion results in an increased yield of these products. An
optimum ratio between the acid sites and metal activity that favors
the formation of ring opening products was found. At lower acid sites/metal
activity ratios the isomerization reaction which leads to C<sub>5</sub> cycle isomers is low, and ring opening by hydrogenolysis is limited
as a consequence. On the other hand, at high acid sites/metal activity
ratios the cracking reactions are favored, decreasing the yield of
RO products