Manufacture of biobased monomers and value-added products from soybean oil.

摘要

The depletion of non-renewable resources by modern societies and the need for a sustainable chemical industry are major factors that contribute to an increasing interest to study and develop new biobased polymers. The specific goal of this research was to study the synthesis of biobased polymer building blocks through ozonolysis of soybean-oil-based fatty acid methyl esters (FAMEs), evaluate their purification feasibility by distillation and evaluate their potential for biobased polymer applications.;Ozonolysis reactions were conducted in two different solvent systems, in both batch and continuous reaction mode. In the first system, methanol was used both as solvent and esterification reagent, while sodium methoxide was added as the esterification catalyst. In the second system, water was used as solvent without catalyst addition. In the methanol system ozone oxidizes the double bonds of unsaturated FAMEs, producing aldehydes (around 50% molar yield) and methyl esters (less than 15% molar yield). With dimethyl azelate as the target compound for biobased polyester building blocks, Oxone was used to convert the aldehydes into methyl esters, improving their molar yields to between 65% and 73%. In the water system, ozonolysis reactions yield aldehydes and carboxylic acids. The products from water system were also primarily aldehydes including hexanal, nonanal and methyl 9-oxononanoate with molar yields between 62% and 71%. For room temperature assays in a continuous system, the optimal flow rate for maximizing product formation during ozonolysis in methanol system was found to be 15 ml/min (ratio of methanol to fame 2:1), while in water system was 40 ml/min (ratio of water to fame 3:1).;For purification of the ozonolysis products from both methanol and water systems, two distillation processes were designed and evaluated using simulation results. A fractional distillation was designed and simulated in Aspen Plus for products generated from the two systems, and most of the purity of products was above 0.99 with recoveries higher than 0.98. As some of the products are sensitive to temperature, an alternative distillation method was evaluated using wiped film distillation (WFD). This system was modeled using an equilibrium simulation with a flash separation module in Aspen Plus to predict the separation efficiency of multiple components. When the operating pressure in WFD is fixed, the study showed that modeling pressure in Aspen Plus is proportional to the pseudo bubble pressure of the mixture under the heating oil temperature of WFD. Since the WFD is similar to one-stage flash separation under a certain pressure, it is not recommended for separation of complex products with close relative volatility, like in the case of mixed products from ozonolysis of FAMEs.;To evaluate the usage of biobased aldehydes for polymer applications, polyvinyl acetals were prepared during polymerization reactions of polyvinyl alcohol (PVOH) with three aldehydes generated from ozonolysis of FAMEs in water system. Properties including decomposition temperature, glass transition and melting temperature for various types of biobased polyvinyl acetals were evaluated and compared with a commercial product polyvinyl butyral (PVB). The above mentioned properties for polyvinyl hexanal (PVH) are comparable to PVB, suggesting that biobased PVH could potentially become a marketable green polyvinyl acetal polymer.