Sustainable Diesel from Pyrolysis of Unsaturated Fatty Acid Basic Soaps: The Effect of Temperature on Yield and Product Composition.

The production of sustainable diesel without hydrogen addition remains a challenge for low-cost fuel production. In this work, the pyrolysis of unsaturated fatty acid (UFA) basic soaps was studied for the production sustainable diesel (bio-hydrocarbons). UFAs were obtained from palm fatty acids distillate (PFAD), which was purified by the fractional crystallization method. Metal hydroxides were used to make basic soap composed of a Ca, Mg, and Zn mixture with particular composition. The pyrolysis reactions were carried out in a batch reactor at atmospheric pressure and various temperatures from 375 to 475 °C. The liquid products were obtained with the best yield (58.35%) at 425 °C and yield of diesel fraction 53.4%. The fatty acids were not detected in the pyrolysis liquid product. The gas product consisted of carbon dioxide and methane. The liquid products were a mixture of hydrocarbon with carbon chains in the range of C7 and C20 containing n-alkane, alkene, and iso-alkane.

The effect of Ca/Mg/Zn mixing ratio on the research octane number of bio-gasoline during basic soap pyrolysis.

Pyrolysis is one of the available technologies to convert oleic basic soap into gasoline-compatible fuel. In this research, the process mentioned was applied using the mixture of Ca, Mg, Zn in the production of oleic basic soap. The reactions were carried out in a batch glass reactor at atmospheric pressure at the temperature of 450 °C. Meanwhile, the basic soaps were made by reacting oleic acid mixed with metal hydroxides. The parameters observed were the Research Octane Number (RON) of bio-gasoline and the hydrocarbon content in the liquid product. The higher the octane number is, the better gasoline resists detonation and the smoother the engine runs. As observed, pyrolysis of oleic basic soap produced gasoline range hydrocarbon. GC-DHA results indicated that the highest RON (89.6) was achieved with Ca/Mg/Zn ratio of 0.15:0.85:1 (Ca-metal ratio of 0.15 mol). The products of the pyrolysis process comprised bio-hydrocarbon, solid residue, water, and gas. The bio-hydrocarbon contents were paraffin (5.9 wt%), iso-paraffin (31.3 wt%), olefin (18.5 wt%), naphthene (25.3 wt%), and aromatic compounds (15.3 wt%).