Deactivation of bi- and multimetallic reforming catalysts: influence of alloy formation on catalyst activity

A number of bi- and multimetallic reforming catalysts including Pt-Re, Pt-L r, Pt-Sn, Pt-Ge and Pt-lr-Ge were prepared and studied in this work. The al loy particles formed in these systems were analysed using transmission elec tron microscopy (TEM) and energy dispersive X-ray analysis (EDX). n-Octane reforming experiments were also performed using a pressurised microreactor system. Tin and germanium were found to modify the properties of these cata lysts mainly via a geometric effect. However, formation of bulk Pe-Sn and P t-Ge alloys contributed to the overall rate of deactivation of these system s. In the case of Pt-Zr and Pt-Re, metallic rhenium and iridium provided si tes for the hydrogenolysis of coke deposits resulting in improved resistanc e to deactivation. (C) 1998 Elsevier Science B.V. All rights reserved.