CATALYTIC SELECTIVITY AND H-TRANSFER IN THE HYDROCONVERSION OF A PETROLEUM RESIDUE USING DISPERSED CATALYSTS

Hydroconversion of a deasphalted vacuum residue of a crude oil has bee n performed in the presence of various disposable, dispersed catalysts at low concentration (450 ppm of metal) under identical conditions: a plasma-prepared nickel-carbon catalyst, an oil-soluble molybdenum nap hthenate, and a commercial nickel-molybdenum supported on alumina, in order to obtain some insight into their influence upon the mechanisms of hydrogen transfer, and to evaluate their selectivities toward the p roduction of various hydrocarbon groups. For this last purpose, a quan titative, rapid and accurate method for hydrocarbon group type analysi s (saturates +/-0.5 wt %, alkylaromatics +/-0.6 wt %, aromatics +/-1.0 wt %, polars +/-0.4 wt % and an uneluted asphaltenic group +/-0.2 wt %) has been used, based on an improved system of thin-layer chromatogr aphy with name ionization detection. The catalysts significantly affec t the quantitative distribution of hydrocarbon groups without producin g new chemical families. The total hydrogen consumption is only slight ly increased in the presence of these kind of catalysts. However, a di fferent distribution of the hydrogen is achieved depending on the cata lyst. Molybdenum naphthenate exhibits the higher hydrogen incorporatio n to its derived distillates, which in turn present significantly high er number-average molecular weight and percentage of saturates than th ose obtained with the other catalysts. For every catalyst studied, the more the incorporation of hydrogen in the distillates, the less the p roduction of coke and gas. Throughout this paper, the agreement betwee n the data obtained from TLC-FID and hydrogen balance is evidenced and explained.