Study On The Synthesis Of Ethyl Lactate

A process for efficient production of ammonium lactate by lactic acid bacteriumin pH-controlled batch fermentation was developed. Effects of pH on the biomass andammonium lactate in batch culture were studied. The final concentration of 136.8gammonium lactate per liter was obtained at the preferable condition of pH 6.5 and 25ml/h glucose fed-batch speed after 80h. The time reached the same concentration ofammonium lactate was approximately decreased 30h. Kinetic models of cell growth,ammonium lactate formation and glucose consumption in batch fermentation wereproposed and kinetic model parameters were determined. The calculated valuesagreed approximately with the experimental data.The magnetic particles of Fe₃O₄ and the solid super-acid catalyst SO₄^2--ZrO₂were assemble to become a novel ultra-fine catalyst SO₄^2--Fe₃O₄/ZrO₂ withmagnetism and strong super-acidity. The magnetic particles of Fe3O4 weresynthesized under the optimum conditions of n(Fe²⁺) /n(Fe³⁺) was 1:6, the mixturesolution of Fe²⁺ and Fe³⁺ dropped to 0.1mol/L NaOH solution and dropped speed was2ml/s. The results showed that the appropriate conditions made SO₄^2--Fe₃O₄/ZrO₂ were as follows: nFe3O4:nZrO2 was 1:10, baking temperature was 5000C. Theyield achieved 84 % with reaction time was 5 hours, weight of catalyst was 6.0% oflactic acid mass, the molar ratio of lactic acid to ethanol was 1:5. The catalyst couldbe isolated from other materials by magnetic separation and the reuse rate exceeded90%. The catalyst was characterized by techniques such as XRD, BET et al .The resultsshowed that average particle size of magnetic particles was smaller than 100nm,andmagnetism(σ_s) overtaken 80emu.g^-1 that was higher than the value had reported. XRDcurves of Fe₃O₄ prepared and standard Fe₃O₄ were essential the same. The specificsurface area of catalyst decreased with the increase of baking temperature, and thatwas 78.9m²/g when baking temperature was 5000C. The kinetics of the reaction of ethanol and lactic acid in the presence of SO42--Fe₃O₄/ZrO₂ were experimentally determined and the model for reactive kinetics wasobtained: At the same time, the problem of inducement period was also found whenthe temperature was lower.An extensive investigation of ethyl lactate synthesis by reactive distillation waspresented for the first time. The one-time yield of ethyl lactate achieved 51.64% infollow appropriate condition: the reflux ratio was 1:1, the molar ratio of ethanol tolactic acid was 4:1, lactic acid feeding flux was 0.6482 mol/h respectively. Based onthe experiment and the model for reactive kinetics, ASPEN PLUS software waschosen to simulate the temperature and concentration using equilibrium-staged model,good agreement between experimental data and the simulation results been achieved.The results indicated that the process was little pollution on the environment and littleerosion on the equipment, and ethyl lactate was a "green" solvent, so that technologywas a "green" technique and will have good prospective in the future.