Conversion of the rosin acid fraction of crude tall oil into fuels and chemicals

Tall oil rosin acid, a forest product industry residue, has been converted into a diesel fuel additive in a single step process. Fractionation of crud e tall oil produces an excess of rosin acids. This material is an abundant, inexpensive and chemically desirable feedstock. Two components, abietic ac id and dehydroabietic acid, comprise about 70% of the rosin acid fraction o f tall oil, The carboxylic acid functionality of these compounds must be re moved and double bonds in the ring structure hydrogenated to obtain diesel fuel additives. Hydrotreatment of the rosin acid fraction achieves both goa ls. The experiments were performed in a laboratory-scale batch reactor usin g three commercial sulfided Ni-Mo and Co-Mo catalysts. For each of the cata lysts, three different factors were studied: temperature, hydrogen pressure , and reaction time. Experiments probe the effects of these variables on li quid product yield, cetane index, hydrogen-to-carbon ratio, and degree of c racking. The liquid products, mainly saturated tricyclic ring compounds, we re analyzed by elemental analysis (C, H, S, and O) and by GC-MS. Boiling po int distributions and densities were also determined. From these data, ceta ne indexes were calculated.