Effect of the nickel impregnation method on clay supports in the hydroconversion reaction of n-decane

Abstract

Ni bifunctional catalysts supported on vermiculite, halloysite and bentonite previously modified by means of delamination or acid treatment were synthesized. The Ni was incorporated using three synthesis methods: auto-combustion (AC), microwave-assisted auto-combustion (AM) and the wet impregnation method (WI). The solids obtained were characterized under different conditions: i) as oxides prior to the reaction, using X-ray diffraction (XRD), N₂ physisorption and temperature programmed reduction (H₂-TPR), ii) under “in situ” reaction conditions using infrared spectroscopy with probe molecule (NH₃-DRIFTS) accompanied by titration with HCl, iii) “ex situ” using high resolution transmission electron microscopy (HRTEM) and iv) post-reaction catalysts were characterized using thermogravimetric analysis (TGA-DSC), Raman and infrared spectroscopy. The catalytic performance of the materials was evaluated in the hydroconversion of decane (C₁₀). In addition, the influence of the impregnation method on the mineral used was analyzed. In the case of the solids obtained from bentonite and halloysite, the methods that most favored the catalytic activity were those of auto-combustion, while in the case of the catalysts obtained with vermiculite as a support, the most favorable method was wet impregnation (WI), which was related to the number of reducible species, the dispersion and acid properties that each method favored depending on the clay mineral used. Finally, all the catalysts presented a high resistance to the formation of carbonaceous residues on their surface, indicating a high activity and low deactivation of the materials.