Enzymatic Synthesis Process Design And Scale-up Of Bio-based Plasticizer-fatty Acid Esters

Plasticizer,usually a kind of low molecular weight and low volatile compound,is widely used for adding in polymer material especially polyvinyl chloride(PVC).As a kind of additive,its main function is to reduce the glass transition temperature(Tg)as well as elastic modulus of the polymer materials,so as to improve the flexibility of polymer materials when processing.In the past decade,plasticizer has a vast market of 8 million tons a year around the globe.Among that,phthalic acid ester is the most commonly used type of plasticizer.But since the early 1880s,a lot of attention and even controversial about the impact on human health and the environment of phthalates appeared.Because of its possible carcinogenic and reproductive toxicity problems,various countries introduce regulations to limit its use.Hence,in order to meet the requirements of the quality of product and regulations,it is a must to committed developing new environmental friendly plasticizer.It was found in previous studies that adding some fatty acid ester into epoxy soybean oil,including fatty acid methyl ester and isooctyl fatty acid,was able to gain access to a mixed environment friendly plasticizer,which has good plasticizing effect.Hence,based on the lipase product(Candida sp.99-125 lipase)which was newly acquired by research group,the synthesis process of fatty acid methyl ester and isooctyl fatty acid was developed,and the synthesis process of fatty acid methyl ester was also industrialized,the results are described below.(1)A new process was developed to catalyze the synthesis of fatty acid methyl ester by lipase fermentation broth and diatomite immobilized lipase.Inthe process of synthesis of fatty acid methyl esterase,the reaction conversionrate of one-step reaction was low(80%).And the diatomite immobilized lipase leads to conglobation during reaction process.Because of it,the process of synthesis of fatty acid methyl ester by lipase fermentation fluid was invented.By stepwise reaction,the decline of catalytic efficiency of immobilized lipase by conglobation was solved.The conversion rate of fatty acid could be up to 95%.Based on the two-step process,from pilot trials to pilot-plant were worked.Besides,there was no significant difference between pilot-plant test and bench-scale test.(2)The process of catalyzing the synthesis of isooctyl fatty acid bydiatomite immobilized fermentation broth was invented.And at the same time,one our own design device can intelligent control the water activity of the reaction developing was used,thus improve the catalytic efficiency.On condition that lipase being 500 U/g(acid),the ratio of the carrier forimmobilization and lipase being 4:1,and water activity being 15%rh,theconversion rate of fatty acids could reach 95% or more.