Selective Ring Opening of Ethylbenzene on Bifunctional Catalyst Pt-Ir over Hierarchical USY Zeolite

摘要

A bifunctional catalyst for selective ring opening (SRO) has been designed using a hierarchical zeolite as support. This material was prepared introducing additional mesoporosity in the microporous structure of a USY zeolite, by surfactant-templating post-synthetic mesostructuring process. Monometallic and bimetallic Pt(x)-Ir(y) catalysts with different metal loadings and Pt/Ir mole ratio have been prepared. In addition, to optimise the acid-metal balance, the acidity of the support has been modulated via ion-exchange process with Na+. The catalytic behaviour of the prepared materials has been evaluated with ethylbenzene hydrogenation and SRO simultaneous reaction in a continuous-flow fixed-bed reactor, at 275 degrees C and 3 MPa. Pt(2)-Ir(1) resulted the most promising metallic combination. The high hydrogenolytic activity of Ir, along with the high hydrogenation activity and cracking limitation of Pt attained a high paraffins production. This behaviour was improved modulating the acidity of the support. Thus, Pt(2)-Ir(1)/Na-FAU-CTAB catalyst maximized the yield to paraffins which improve the cetane number of fuels.