Thiotolerant Ir/SiO2–Al2O3 bifunctional catalysts: Effect of metal–acid site balance on tetralin hydroconversion

The hydroconversion of tetralin over iridium nanoparticles supported on amorphous silica–alumina (ASA) has been investigated in a continuous high-pressure gas-phase micro-reactor in the presence of H2S. In order to tune the Ir particle size, the bifunctional Ir/ASA catalysts have been submitted to sintering treatments. The samples have been characterized by HRTEM and XPS. From careful analysis of tetralin conversion products by comprehensive two-dimensional gas chromatography (GC×GC–MS) and NMR, compound families have been unambiguously distinguished. Hydrogenation, dehydrogenation, (saturated and aromatic) ring-contraction products, and (saturated and aromatic) one-ring-opening products are formed, without significant cracking. The catalysts exhibit stable activity in the presence of sulfur. As the mean particle size increases from 1.5 to 8 nm, the ring-opening/contraction selectivity increases dramatically. This effect is related to an increase of the acid/metal site ratio.

Ir supported on amorphous silica–alumina is sulfur tolerant and catalyzes tetralin hydrogenation, ring contraction, and ring opening without cracking. The selectivity to ring opening increases with the acid/metal site ratio.Figure optionsDownload high-quality image (110 K)Download as PowerPoint slideResearch highlights
► Ir nanoparticles supported on amorphous silica–alumina are resistant to sulfur.
► Tetralin is hydroconverted to decalins and ring-opening/contraction products.
► The selectivity to ring-opening products increases with the acid/metal site ratio.
► The GC×GC–MS technique was used to separate ring-opening products.