Abstract: A catalyst for the hydrogenation of a hydrocarbon material which is a member selected from the group consisting of red mud, iron oxides, iron ores, hard coals, lignites impregnated with heavy metal salts, carbon black, soots from gasifiers, and cokes produced by the hydrogenation of virgin residues, the catalyst being comprised of at least two separate particle size fractions such that the combined fractions have a particle size distribution between 0.1 and 2,000 microns with 10-40 wt. % of the particles having a particle size greater than 100 microns, and the mixture of fractions not being represented by a straight line when the accumulative weight of the particles vs. particle size which is plotted on log (minus log) vs. log graph paper has a correlation coefficient R.sup.2 less than 0.96 as determined from the equation: ##EQU1## wherein n is the number of experimental points, y is ln [-ln (n/1000)] and x is ln (dp), wherein dp is the particle size (.mu.m) of the particles.

Abstract: Process for the hydrogenative conversion of heavy oils and residual oils, used oils and waste oils, mixed with sewage sludge in a typical liquid phase hydrogenator with gases containing hydrogen, with the addition of a finely ground substance that preferably has a large internal surface area, as additive. The additive is added in two different particle size ranges so that a portion of the additive is present as a fine particle size fraction iwth a particle size of 90 .mu.m or less and another portion as a coarse particle size fraction with a particle size of 100 .mu.m to 2000 .mu.m, preferably 100 to 1000 .mu.m with the procedure being carried out with a weight ratio of raw oils to sewage sludge used of 10:1 to 1:1.5. Conversion of vacuum residue of a Venezuelan heavy oil with the addition of 2 wt. % of lignite coke as additive and with the admixture of 10 wt.

Abstract: A process for the hydrogenation of heavy oils, residual oils, waste oils, used oils, shell oils, and tar sand oils by hydrogenating a slurry of the oil at a partial hydrogen pressure of 50-300 bar, a temperature of 250.degree.-500.degree. C., a space velocity of 0.1-5 T/m.sup.3 h, and a gas/liquid ratio of 100-10000 Nm.sup.3/ T, wherein the additive comprises two different grain size portions, a fine grain portion having a grain size of 90 microns or less and a coarse grain portion having a grain size of 100-1000 microns.