Novel (Co-,Ni)-p-tert-Butylcalix[4]arenes as Dispersed Catalysts for Heavy Oil Upgrading: Synthesis, Characterization, and Performance Evaluation

This study investigates the promotional effects of a potentially new class of oil-soluble dispersed catalyst precursors for the upgrading of vacuum gas oil (VGO), i.e. metal-based p-tert-butylcalix[4]arenes (TBCs[4]). Co- and Ni-TBC[4] were synthesized, where the metal-ligand complexation was confirmed by SEM-EDX, ICP, XRD, UV-Vis, FT-IR, and 1H NMR. The thermogravimetric and calorimetric behaviors of the synthesized complexes, which are key properties of dispersed hydrocracking catalysts, were also studied. The differential scanning calorimetry (DSC) profile of Ni-TBC[4] and Co-TBC[4] showed that the organometallic structure has lower thermal stability compared with that of the parent TBC[4]. This apparent drawback can be positively exploited by employing the TBC[4] as a carrier of the metal, where the active sites are formed in-situ by the destruction of the organometallic complex upon reaching the desired reaction conditions. The catalytic performance of the synthesized precursors was evaluated using a...