Petroleum residue upgrading with dispersed catalysts Part 1. Catalysts activity and selectivity

The results of a study aimed at the identification of the relevant chemical aspects involved in the process of upgrading heavy feedstocks in the prese nce of dispersed catalysts are discussed. The catalytic activity of differe nt compounds was compared in terms of products yields and quality. Moreover , a detailed and systematic characterization of the catalysts recovered at the end of the reactions was achieved. The experimental work provided quite a large set of data, allowing to investigate the factors that may affect c atalyst activity (precursor solubility, rate of activation, degree of dispe rsion, presence of promoters etc.). The results of this study demonstrate t hat the best performances are obtained by the microcrystalline molybdenite generated in situ by oil-soluble precursors. The nature of the organic Liga nd does not play a very relevant role in influencing the hydrogenation acti vity. The presence of phosphorus, however, significantly enhances hydrodeme tallation, at least in terms of vanadium removal. Bimetallic precursors sho w a slight synergistic effect towards the hydrodesulfurization reaction, Mi crosized powdered catalyst precursors have a much lower catalytic activity compared to the oil-soluble ones. (C) 2000 Elsevier Science B.V. All rights reserved.