Renewable gasoline production from oleic acid by oxidative cleavage followed by decarboxylation

Hydrocarbons in a range of the renewable gasoline chain-length were produced by oxidative cleavage of unsaturated fatty acid, oleic acid, followed by decarboxylation. The effects of the emulsifier, concentration of oxidizing agent, reaction temperature, and atmospheric conditions were investigated. As a result, the optimum condition was found for oxidative cleavage to be 1.0 wt% emulsifier, KMnO4/oleic acid = 4/1 (mol/mol), at 40 °C, for 30 min to obtain about 93 mol% pelargonic acid (C9 monocarboxylic acid) and 86 mol% azelaic acid (C9 dicarboxylic acid). Decarboxylation of these obtained short-chain fatty acids, pelargonic and azelaic acids, gave 98.2 mol% n-octane (C8) and 73.1 mol% n-heptane (C7), respectively, under the appropriate conditions of 300 °C/10 MPa and 300 °C/5 MPa (N2 pressure) with 6 mol% Pd/C for 2-3 h. Although decarboxylation of azelaic acid resulted in lower yield, the obtained results highlight a potential of plant oil conversion to hydrocarbons as renewable gasoline.