Oxygenated biofuels from butanol for diesel blends: synthesis of the acetal 1,1-dibutoxyethane catalyzed by amberlyst-15 Ion-exchange resin

The synthesis of 1,1-dibutoxyethane or acetaldehyde dibutylacetal was studied in a batch reactor by reacting butanol and acetaldehyde in a liquid phase, using Amberlyst-15 as the catalyst. The reaction equilibrium constant was experimentally determined in the temperature range 20-40 °C at 6 atm, where Ka = 0.00959 exp[1755.3/T (K)]. The standard properties of the reaction at 298.15 K were estimated: ΔH° = -14.59 kJ mol-1, ΔG° = -3.07 kJ mol-1, and ΔS° = -38.64 J mol-1 K-1. Kinetic experiments were performed in the temperature range 10-50 °C at 6 atm. A two-parameter kinetic law based on a Langmuir-Hinshelwood rate expression, using activity coefficients from the UNIFAC method, was used. The kinetic parameters are kc = 2.39 E9 exp[-6200.9/T (K)] (mol gcat -1 min-1) and ks,D = 2.25 E-4 exp[3303.1/T (K)]. The activation energy of the reaction is 51.55 kJ mol-1. This work is an important step for further implementation of an integrated reaction-separation process, such as a simulated moving-bed reactor