Hydrogenation and ring-opening of tetralin on Ni and NiMo supported on alumina-pillared α-zirconium phosphate catalysts.: A thiotolerance study

Two different nickel supported on alumina-pillared ce-zirconium phosphate materials with metal loading of 20 and 30 wt% have been prepared. In both cases, before reduction, the typical lines of NiO are observed in the XRD patterns. The reduced catalysts exhibit similar metallic area and dispersion values. On the other hand, the catalyst with 20 wt% Ni has the highest surface acidity. Two other NiMo catalysts with 20 wt% Ni and 5 or 10 wt% Mo have been also synthesized. Their XRD patterns show the presence of the NiMoO4 spinel together with an excess of the NiO phase. XPS analysis reveals the existence, in both samples, of 51 and 76% Ni as spinel. After reduction, all these catalysts were tested in the hydrogenation and ring-opening of tetralin at 6.0 MPa. The catalyst with the lowest Ni content (20 wt%) is very active at 623 K, with a conversion of 85% and a high yield of decalins (40%) and cracking compounds (CC) (close to 45%). However, these catalysts strongly deactivate in the presence of 1000 ppm of dibenzotiophene (DBT) in the feed. The incorporation of molybdenum to these catalysts (Ni: Mo weight ratios of 20: 5 and 20: 10) favours the ring-opening to the detriment of the hydrogenation process, attributable to new acid sites associated with the molybdenum species. In addition, the NiMo-20: 10 catalyst exhibits a high thiotolerance in the presence of 1000 ppm of DBT, maintaining its activity after 7 h of time on stream, with a conversion higher than 65% and with good yield of decalins (45%), and maintaining an interesting yield of cracking compounds (18%). (C) 2001 Academic Press.