Hydrotreating of non-food feedstocks over Raney nickel for the production of synthetic diesel fuel

ABSTRACT

Non-food feedstocks including castor oil, palm fatty acid distillate and waste tallow were successfully converted into liquid hydrocarbon mixtures. This was achieved by a batch hydrotreating process over commercial Raney nickel as a catalyst within 5 h at a reaction temperature of 360 °C and an initial hydrogen pressure of 90 bar. The obtained liquid products consist of straight chain alkanes in the range from C₈ to C₂₀. Low amounts (2.5–4.4%) of higher n-alkanes (up to C₂₈) could be detected. The occurrence of the latter indicates a Fischer-Tropsch like process under the chosen conditions besides the expected decarbonylation/decarboxylation and accompanying cracking reactions. Products obtained from castor oil also comprised an overall amount of 19% of ketones in the range from C₈ to C₁₉. All obtained products were tested on important fuel properties according to well-established methods given in EN 590, the European Standard for diesel fuel. Comparison with the obligatory boundary values given within this specification suggests an excellent suitability as blending components for fossil diesel fuel. For a full replacement further upgrading would be necessary.

KEYWORDS:

• Synthetic diesel fuel
• hydrotreatment
• Raney nickel
• biofuel
• non-food feedstock

Disclosure statement

No potential conflict of interest was reported by the authors.