| The energy and environmental issues are the two of main problems which human society now faced. How to deal with or realize the harmonious development of these two problems became a challenge for all humans including our researchers. Since the 21st century, the rapid development of industrial biotechnology has given solutions for various bottleneck problems of traditional industry faces. Therefore, the industrial biotechnology is an appropriate solution for energy and environmental problems. Liquid bio-fuels, one of the most important forms of bio-energy, as its good compatibility with traditional fossil fuels, are now being widely used. Furthermore, the synthesis technology of liquid biofuels from biomass has become one of the hotspots in bioenergy research.Waste cooking oils (WCOs), as its potential food security issues, are mainly been used as raw materials for liquid biofuels. However, the complex origins of WCOs making the traditional transformation methods difficultly,. Therefore, how to efficiently transform WCOs to high quality liquid biofuels with low cost was the main problem for the development of the technology. Due to the reason above, a new process of Candida sp.99-125 lipase synthesized biodiesel with glucose as additive was developed in this work. The use of glucose as assistant lower the cost of biodiesel synthesis process, and a industrial equipment with capacity of 30 thousands tones annual was established. Meanwhile, in order to expand the application scope of WCOs, the hydrodeoxygenation, hydrocracking and hydroisomerization of fatty acids methyl esters (FAMEs) from WCOs was attempted to transform it into bio-jet fuel. Finally, a new one-step process of transforming FAMEs to bio-jet fuel was developed and the catalyst for this process was designed and prepared. The results are as follows:1. In order to efficiently transform WCOs to biodiesel and lower thecatalyst cost, a new enzyme catalyzed biodiesel synthesis process with Candida sp.99-125 lipase and glucose as assistant of the lipase was developed. The optimal conditions were:lipase dosage 40U/g oil, the weight of additives to lipase was 1:1(w/w), temperature 40℃, water content 2 wt%, stoichiometric amount of methanol added 6 times in 24h,200rpm. The use of glucose as assistant lower the cost of the process, and the process were scaled up to 200 L,5,000 L,10,000 L, with the yield of 90.8%,90.2% and 89.2%, respectively. Furthermore, a low cost treatment process for enzymatic solution without distillation was developed. The cost of the process was 195 RMB/ton. the cost of non-distillation process was 25% of the original process, and the product was used in low speed diesel engine for over 100 hours successfully.2. The high contents of saturated fatty acid in WCOs led to poor low temperature property of biodiesel, which limited its usage. In order to improve the low temperature property of biodiesel, two methods were attempted in this thesis:the combined urea complexation and synthesis of isopropyl ester (UCIE), and synthesis of fusel alcohol fatty acid ester (FAE). Using UCIE method, the cold filter plugging point (CFPP) of biodiesel could decrease from 5℃ to-3 ℃. Furthermore, the molecular dynamics simulation result showed an obvious increase of average molecular distance in UCIE system, which meant that the isopropyl ester prevented the crystallization process. Meanwhile, fusel alcohols, a low cost resource of branched chain alcohols was found and the fusel alcohol fatty acid ester was synthesized to improve the low temperature property of biodiesel. With FAE treatment, the CFPP of biodiesel decreased from 5℃ to-11 ℃, which expanded the application of biodiesel.3. In order to expand the application scope of WCOs, and eliminate the shortcoming of high oxygen content, a non-sulfured Ni-Mo/y-Al2O3 catalyst was prepared. The catalyst was used for the hydrodeoxygenation process of FAMEs. Meanwhile, the type and loading amounts of active metal were identified. The optimal active metal was Ni-Mo, and the loading amounts of Ni and Mo were 5% and 10%, respectively. Using this catalyst, the hydrodeoxygenation ratio of FAMEs and the contents of bio-jet fuel in the product could reach up to 97.1% and 24.4%, respectively. Furthermore, the catalyst was characterized by XRD, SEM and EDS.4. Normally, the process of transforming FAMEs or oil and fats to bio-jet fuel including a multi-step process of hydrodeoxygenation, hydrocracking, and hydroisomerization. However, the traditional process led to a high process lost and low bio-jet fuel yield. Based on this, a new one-step process was established in this thesis, which combined the three processes with a multi-functional catalyst. The one-step catalyst was a combination of the Ni-Mo/γ-Al2O3 catalyst and modified Meso-SAPO-11. With this catalyst, the FAMEs could be transformed to bio-jet fuel directly. In this process, the hydrodeoxygenation ratio of FAMEs and the contents of bio-jet fuel reached up to 98.8% and 59.8%, respectively. Furthermore, the total yields of bio-jet fuel in one-step process could increase to 40.2%, which were higher than traditional multi-step process. |
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