An investigation was carried out to study the feasibility of using 5% nickel/alumina catalysts synthesized with different methods and metal precursors for the hydrogenation of tetralin. The catalysts were characterized using atomic absorption spectroscopy, thermogravimetric analysis, X-ray powder diffraction, X-ray photoelectron spectroscopy (XPS), hydrogen chemisorption, and surface area and pore volume analyses. The catalysts were tested in a continuous-flow, fixed-bed, reactor using solvent-free tetralin feed under the conditions of 5 barg hydrogen, 210 °C, a weight hourly space velocity of 5 h −1 , and a H 2 /HC ratio of 7.5 (gas hourly space velocity, 4220 h −1 ). These reaction conditions were much milder than the ones reported in literature but showed considerably higher catalytic activity even with low metal loadings. The study indicated that the product's isomer ratio was governed by kinetics. Indeed, a remarkable difference was observed in the selectivity for the catalysts synthesized with different metal precursors in relation to cis/trans decalin ratios, where catalysts derived from nickel carbonate showed higher selectivity to cis-decalin compared to catalysts prepared from nickel nitrate. It was speculated that the dispersion and particle size played an important role in this variance, as suggested by XPS and hydrogen chemisorption. It was also found that this change in selectivity was not related to conversion. Similarly, different deactivation patterns were observed over these catalysts.

Catalyst deactivation is a well-recognized phenomenon in the petroleum and chemical processing industries. Identifying the root causes of this phenomenon is an important factor for enhancing catalyst efficiency and preventing undesirable failures. In this study, state-of-the-art instruments were utilized to investigate the causes of catalyst deactivation that led to the replacement of the catalyst bed in one of the sulfur recovery units at a Saudi Aramco gas plant. Titania catalysts have been examined to determine the inherent deactivation mechanism and also to find out the possibilities of its curement. Understanding the root cause of the deactivation is mandatory for field engineers to minimize future catalyst deactivation. The collected analysis data revealed that the deactivation mechanism occurred for the Ti catalyst due to irreversible chemical phase transformation of the catalyst caused by a temperature runway in the catalytic converter.

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