Study On Biodiesel Synthesis By Transesterification With Microbial Oil

Biodiesel is a kind of renewable energy, the investigation was carried out preparation of biodiesel from microbial oil, which was fermentated by Mortierella alpina. In this work, three aspects were studyed:The NIR analysis technology was used for corn fiber quantitative analysis; Preparation of microbial oil from corn fiber; Preparation of biodiesel from microbial oil.This study discussed the moisture, ash, fibre, hemicellulose, lignin, starch, protein and fat in corn fibre by FT-NIRS. We used GB methods measured the composition of corn fiber. Chemical value and the near-infrared spectrum of synchronous detected by means of NIRS instruments of BUCHI N-400 FT-NIR, the Q value was 0.693012. The sample in the process of extraction, which did not participate in modeling were used to test the performance of the models.The result showed that the biomass was 19.35g/L and the lipid concentration reached 42.12%with the optimal fermentation temperature 28℃after 96h clture in 10L bioreactor. The rotation speed, air flow rate and corn fiber hydrolysate ratio were 200r/min,0.5v/(v·m) and 80%, (NH4)SO4, MgSO4, K2HPO4 and KH2PO4 addition. The microbial oil was extracted from dry-thallus, and the effect of differernt extraction process, organic solvents and time on lipid extraction was studied. The oil extracted with Soxhlet's extractor is pure than that with DMSO, and the extractant is petroleum ether(60-90℃), the circumfluence temperature is 95℃, circumfluence time is 8 hour.Two-step way prepared biodiesel was focused on in present work. Single factor experiments of the microbial oil biodiesel process, which used concentrated H2SO4 as a catalyst to reduce oil acid value was used to obtain the optimal reaction conditions as follows:the catalyst concentration of 5%methanol to oil molar ratio 12:1, reaction temperature is 65℃and reaction time 2h. During the optimization of reaction conditions, the acid value may drop to below 2mgKOH/g which meets the next step ester exchange response requirement.Based on single factor experiments (Response Surface Methodology, RSM), and using the Box-Benhnken center unitized design experiment and the response surface analysis, we came to a conclusion on the optimum response condition of ester exchange response under the using of KOH as follows:the catalyst concentration of 1.25%, methanol to oil molar ratio 10:1, reaction temperature is 57℃, reaction time was 1.47h. The microbial oil system were taked the biodiesel under this response condition to receive rate can up to 90%, while the fatty acid methyl ester mainly contained 16 or 18 carbon atoms. Physical and chemical indicators of biodiesel were determined. Main performance indicators of product were in line with national standards.