Transition metal tetrachloroaluminate catalysts for probe reactions simulating petroleum resids upgrading

Several transition metal tetrachloroaluminates [MCl_x-(AlCl₃)_x] have been evaluated as catalysts for probe reactions simulating petroleum resids upgrading. Six transition metal chlorides, VCl₃, CoCl₂, NiCl₂, ZnCl₂, MoCl₃ and PdCl₂, and three kinds of alkali metal chlorides, LiCl, NaCl and KCl, were used for preparing the catalysts. We selected four compounds as models, including 4-(1-naphthlymethyl) bibenzyl (NMBB), eicosane (n-C₂₀), dibenzothiophene and pyrene. Batch tests were carried out at 425 °C for 20 min under hydrogen pressure. Very interesting results were obtained from model compounds reactions that demonstrated the unusual and promising feature of transition metal tetrachloroaluminates. For example, some of the transition metal containing catalysts were found to strongly promote hydrocracking of a long-chain paraffin to levels which are 200-300% of those achieved with alkali metal tetrachloroaluminates. Mo-containing catalyst displayed especially higher activity for desulfurization and hydrogenation. The results of NMBB reactions provided insight into reaction mechanism, and the selectivity of cleavage of C-C bonds in NMBB correlated with the i-C₄/n-C₄ ratio of the gaseous products, which is a relative measure of the acidity of the catalysts.