Enzyme Immobilization And Catalytic Synthesis Of Biodiesel In The Ionic Liquid

Biodiesel,a renewable, biodegradable, nontoxic and cleaning fuel, is made from plant oil or animal oil,is expected as a part of substitute for conventional fossil diesel. Biodiesel could have advantanges of solving energy crisis and reducing the emission of Greenhouse Gas.Respectively,tung oil from the south of Shaanxi province was assayed by chemical analysis technologe, its compositions of fatty acid was discovered with gas chromotography, and the behaviors of its thermal mass loss was investigated by thermogravimetry.As results, the main physical and chemical indexes of Tung oil were acid value 3.6601 mgKOH.g^-1, iodine value 167.2g.100g^-1,saponification number 191.6mgKOH.g^-1,paroxide value 4.428mol.L^-1.Gas chromatograpy analysis showed that the fatty acids of Tung oil consisted of hexadecanoic acid 3.51%, linolenic acid 15.61%, linoleic acid 3.58%, oleic acid 1.75%, eleostearic acid 73.81%, stearic acid 1.74%.Biodiesel from Tung oil was researched on the thermogravimetry property.The experimental results showed that the effects of different heating rates were indistinct for pyrolysis. At the same time,I found that Tung oil was the better materials for preparation biodiesel than the others.The partition behavior of Candida antarctica lipase (CAL) in aqueous two phase system(ATPS) was investigated. Respectively,temperature, molecule mass of polyethylene glycol(PEG),the concentration of NaCl and the concentration of ammonium sulfate were studied.The results showed that in ATPS, temperature was unimportant for partition coefficient of CAL (L_CAL),while the electric potential difference between top and bottom phase was important. It was also discovered that the less the molecule mass of PEG was, the more favorable conditions for the CAL congregation into the phase because of the increased hydrophobicity were formed. Under the room temperature, the optimized extraction conditions were as follows: 20% PEG, 12% (NH₄)₂SO₄,1.5%NaCl, and K_CAL was 81.6, the recovery rate of CAL was 91.6%.To study on mechanism of Candiada antartica lipase immobilized with macroporous carriers by adsorption.For four different carriers (NW-ZT2, NW-ZT3, NW-ZT4, NW-ZT1), their pore size distributions were investigated with the auto-absorption instrument by nitrogen low tempera -ture adsorption method. The behavior of lipase immobilized was researched by adsorption & cross-linking method, and immobilization lipase mechanism has been studied.NW-ZT2 should be the best carrier among these four carriers., and it's optimal conditions for immobiliza -tion: the amount of lipase 1400-1600ug/ml, glutaraldehyde concentration of 0.05% (V/V), buffer pH7.5, adsorption temperature 30℃,adsorption time 10h.We found that NW-ZT2 carrier was an ideal carrier for immobilizing Candiada antartica lipase by absorption. During the reaction processes with immobilization lipase as catalyzer, the loss of immobilization lipase activity was caused by lipase falling off the carrier. At the same time, we found it could play a role in strengthening lipase that lipase immobilized by absorption & cross-linked with NW-ZT2 and glutaraldehyde.In this paper, Candida antarctica lipase was immobilized by absorption & cross-linked method with NW-ZT2 and modified-conjugation method with silica gel-PEGThe final product silica gel-PEG-lipase(named Limczyme) was proved by analyzing IR spectrums.We have studied the optimum pH value, the optimum temperature, the thermo-stabilities and operational stabilities for two kinds of immobilized lipase.The study results show that the silica gel-PEG-lipase was better than the immobilized lipase by adsorption-cross-linked (named Liaclzyme), and both of them were efficient for transesterification reactions.There are some advantages for ionic liquids with non-volatile, non-combustible, electrical conductivity, big heat capacity, and small vapor pressure, stabilities and good solubility for many inorganic and organic compounds. Enzymes in ionic liquids have good catalytic properties.By inspecting the reaction temperature and reaction time,(?) determined the molar ratio 1:1 for chlorophthalic add n-butane and N-methyl imidazole,and reaction temperature was 75℃,reaction time was 54h, the reaction products(FAMEs) yield was 83.9% in [BMIM]C1; For the second step reaction, using intermittent microwave irradiation heating method to prepare [BMIM][BF₄],each heating 15s, stirring 30s with the magnetic stirrer after stopping heating.Finally,the total reaction time of heating 210s, [BMIM] Cl with NaBF₄ the molar ratio of 1.1:1,the yield of [BMIM][BF₄] based on the N-methyl imidazole was 86.3%. With Magnetic Resonance Spectroscopy,the results of the analysis confirmed that the end product was indeed [BMIM][BF₄]. Optimizing reaction conditions, I obtained the best technology parameters of preparation biodiesel from Tung oil using Limczyme as catalyzer by transesterification reaction: [BMIM] [BF₄] as reaction medium, pH7.5, reaction temperature 40℃,water content of 10%, immobilized lipase Limczyme amount of 5%, shaker speed of 200rpm, reaction time of 48 hours. As double substrates, the molar ratio of methanol to Tung oil should be maintained at 1.0, used to add methanol approach step by step,named "transesterification sieve plate theory".The kinetic of Limczyme catalyzed preparation of biodiesel was consistent with the double substrates Ping-Pong Bi Bi mechanism of alcohol inhibition mechanism. Kinetic equationobtained was (?),and the largest reactionrate V_max=1.76×10^-3mol.m^-3.min^-1.g^-1,the Michaelis constant Tung oil aK_m1=0.5738mol.m^-3, the Michaelis constant of methanol K_m2=1.3746mol.m^-3,methanol inhibition constant K_iMe= 0.2025mol.m^-3.