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 K a = 0.00959 exp[1755.3/ T (K)]. The standard properties of the reaction at 298.15 K were estimated: Δ H ° = −14.59 kJ mol −1, Δ G ° = −3.07 kJ mol −1, and Δ S ° = −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 k c = 2.39 × 10 9 exp[−6200.9/ T (K)] (mol g cat −1 min −1 ) and k s,D = 2.25 × 10 −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.