<b>Evaluation of the density, volatility and anti-knock rating physical-chemical properties of alternative butanol/gasoline fuel blends

Resumo

Butanol, popularly known as butyl alcohol, has been recently recognized by researchers from around the world as a promising component for use in blends with gasoline, because of its very similar physical-chemical properties. In this study, butan-1-ol (n-butanol) and 2-methylpropan-1-ol (isobutanol) were blended with pure gasoline in proportions of up to 30% mass. The blends density, volatility and anti-knock rating were experimentally determined and compared with Brazilian commercial gasoline specifications. The results showed that the blends properties kept a strong dependency on the linear or branched butanol molecular structure and with the interaction effects of its hydroxyl groups. In the blends, a polynomial increase in density was observed, with a consequent volatility reduction, affecting the vapor pressure and distillation curve, especially for specified 50 and 90% evaporated temperatures (T50 and T90). Minor effects were observed at the T10 and FBP curve extremes. Octane rating and anti-knock index gains were observed, with noted increase of MON for 2-methylpropan-1-ol based blends. At the tested butanol content range, blends characteristics presented satisfactory compatibility with Brazilian gasoline specifications.