| The most attractive feature of poly-[3-hydroxybutyrate](PHB) is that its physicalproperties are comparable to conventional plastics. However, the unique exception isthat PHB is able to be aerobically degraded to carbon dioxide and water by a numberof different soil-bacteria and fungi. As a result, PHB has gained much attention in theplastic industry. 3-Hydroxybutyrac acid and ethyl 3-hydroxybutyrate are the mainmonomers for producing PHB, an important biodegradable plastic. By far, monomershave not been produced on commercial scale. The research described in thisdissertation focuses on the oxidization of 3-hydroxybutyraldehyde, the esterificationof 3-hydroxybutic acid, and determination the corresponding viscosity data of theoxidized system in different temperature and isobaric vapor-liquid equilibrium forethyl 3-hydroxybutyrate-ethyl crotonate-ethanol system at 101.325KPa.The effects of structure parameters of the airlift loop reactor (ALR) on theoxidation of 3-hydroxubutanal were studied. The optimal structure was confirmed.Liquid circulation rate and gas holdup in an ALR were experimentally investigated aschanging with the superficial gas velocity for the system of air-water. Relationshipsbetween gas holdup and liquid circulation rate were established on the basis of themomentum balance and drift-flux model, the method of determining localfrictional-loss coefficients was introduced, and the coefficients and the distributionparameter were calculated. The calculation result by this model showed that relatederrors of liquid rates and gas holdup between calculated value and their experimentaldata were 2.50% and 0.39 % respectively.Using 3-hydroxybutanal, oxygen and air as raw material, the 3-hydroxybutic acidwas synthesized by liquid phase oxidation in 0.5L ALR. In the experiment, the variousfactors which influenced the synthesization of 3-hydroxybutic acid were studied. Theresult showed that the reaction time was the most remarkable effect factor for theyield of the synthesized reaction, the amount of the solvent and the reaction pressurewere secondly, and other effect factors were less for the yield. By orthogonalexperimental design, the optimal reaction conditions were obtained which were thefollowings: reaction time being 5h, reaction pressure being 1MPa, the rate of oxygenflowrate being 0.30L/min, the temperature of reaction being 60℃, and themass ratioof solvent and catalyst cobalt acetate to 3-hydroxybutanal being 100%,0.5%respectively. Under the above conditions, the yield was 88.99%. 3-Hydroxybutic acidwas synthesized in another 4L loop reactor which was designed and manufactured byourselves. The orthogonal analysis showed that reaction time was the mostremarkable effect factor for the yield. the minor factors were the solvent amount andthe reaction pressure .The optimal reaction conditions were following:time being5h,pressure being 1MPa,oxygen flow rate being 0.16m3/h,temperature being 60℃,mass ratio of solvent and catalyst cobalt acetate to 3-hydroxybutanal being140%,0.5%respectively. Under the above conditions, the average yield was 88.1%.Preparation of ethyl 3-hydroxybutyrate from 3-hydroxybutyric acid and ethanolwas studied, too. Reaction was carried out in a Soxhlet extracting set. Various reactionparameters were also examined. Experimental results showed that the productivity ofethyl 3-hydroxybutyrate was obviously improved by adding dehydrating agent andwater carrier in the reaction system. The productivity of ethyl 3-hydroxybutyratecould be 96.60% under the following optimum conditions: 3-hydroxybutyric acid 0.1mol, ethanol 0.12mol, paratoluenesulfonic acid 0.7175 g, cyclohexane 50 mL,CaO18.70 g and reaction time 3h.
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