| It is well known most of the present commercial biodiesel is produced from oils catalyzed by liquid acid or liquid base.However,these technologies for biodiesel production have many disadvantages including the high cost for feedstocks,the difficulties in catalysts recycling and products separation,and large quantity of wastewaters coming from during the biodiesel prouction process.To solve these problems choosing cheap oil raw materials and heterogeneous catalyst for biodiesel production is an effective treatment approach.Therefore,two cheap non-edible oils,soybean acid oil（SAO）and Jatropha oil were chosen as feedstocks of biodiesel in this study.According to the characteristics of the selected lipid feedstocks,the catalytic esterification of SAO with commercial strong acid ion exchange resins and the catalytic transesterification of Jatropha oil with modified bentonite solid base were set up to synthesize biodiesel.The main research contents and the corresponding results are as follows:1.The esterification of free fatty acids（FFAs）in soybean acid oil（SAO）reacting with methanol over four commercial strong acid cation-exchange resins for synthesizing biodiesel were studied.The corresponding reaction conditions of the catalytic esterificatio were optimized.In addition,the activity and stability of the optimal resins in the esterification of different oil feedstocks having high FFAs were assessed.Besides,the esterification kinetics and thermodynamics of the reaction of the FFAs in SAO with methanol were studied.The results are as follows:（1）the optimal resin（LS-50）had a high catalytic activity with high FFAs conversion（91.02%）in the esterification of SAO under the conditions of a catalyst/oil mass ratio of 6.0 wt%,reaction temperature of 120℃,methanol/oil molar ratio of 13.86:1,600 r·min-1 stirring speed and 140 min reaction time.Under the same conditions,the respective FFAs conversions of the esterification reactions of another three oils including palm acid oil（PAO）,frying waste oil（FWO）and cook waste oil（CWO）with methanol were 93.62%,89.73%and 87.35%.（2）Moreover,LS-50 could be successfully reused for at least 8 cycles in the esterification of PAO and SAO.However,its deactivation was found in the reuse of the esterification of FWO and CWO,which was attributed to that a part of H+ ions on the sulfonic acid groups were exchange by sodium cations and iron cations in the two oils.The deactivated resin can be regenerated by acid activation.（3）Within 90～120℃,the esterification reaction of SAO and methanol catalyzed by LS-50 fitted well to the pseudo-second-order kinetic model.（4）The thermodynamic study indicated that the esterification reaction of mix fatty acids and methanol was an exothermic and spontaneous reaction.2.Jatropha oil was converted to biodiesel by catalyzed with solid base.Bentonite and its modified products were applied in the refining of raw lipid material,biodiesel synthesis and crude biodiesel purification process.（1）Crude Jatropha oil was refined with the activated clay that loaded with citric acid and calcium hydroxide,respectively.The effecting factors of degumming and deacidification for crude Jatropha oil were investigated.Finally,the degumming and deacidification process were coupled together.to strengthen the refining process in one-step.The results indicated that the phosphatide content of the refined Jatropha oil decreased to 0.09 mg·g-1 and the acid value decreased to 0.23 mgKOH·g-1 in the one-step refinement process.When the refined oil was used as the feedstock,catalyzed by a homogeneous alkaline catalyst,for biodiesel production,the mass fraction of methyl ester in the final product is greater than 99%.（2）Bentonite-type solid bases prepared by modifying successively activated clay（AC）with Ca（OH）2 and NaOH were applied in the transestcrification of Jatropha oil and methanol.Moreover,the relationship between the structure of catalyst and catalytical performance was extensively explored with the help of analytical technologies including Hammett indicator method,CO2-TPD,FT-IR,XRD,N2 adsorption and SEM.The results showed that the catalyst prepared using NaOH dosage of 3.0 mmol·g-1,Ca（OH）2 dosage of 9.0 mmol·g-1 and calcined at 200℃ for 2 h,showed the optimum catalytic performance.In addition,it displayed higher activity than the catalyst without the participation of Ca（OH）2.The characterization results showed that Ca（OH）2 could neutralize or cover the acid sites of AC,which could protect the montmorillonite structure of AC from NaOH corrosion to some extent,improve the formation of strong base sites on AC and enhance the performance of catalyst.（3）The optimal solid base was applied to catalyze the transesterification of Jatropha oil and methanol,and the kinetics and the thermodynamics of the transesterification reaction was studied.Results showed that the solid base had a high catalytic activity and a catalytic selectivity,employing a catalyst/oil mass ratio of 3.0 wt%,reaction temperature of 65℃,methanol/oil molar ratio of 12:1,reaction time of 4 h and stirring speed of 600 r min-1,an oil conversion of 96.70%was achieved.And the catalyst maintained an acceptable activity in reuses test,and the conversion still over 80%in the third use.The activity of the used catalyst was recovered by treatment with the reclaimed filtrate from the catalyst preparation process.Moreover,the transesterification reaction can be well described using the pseudo-first-order kinetic model with the activation energy of 67.87 kJ-mol-1.And the thermodynamics analysis reveals,in the temperature range of 50～65 ℃,the standard Gibbs free energy change of the reaction is positive,the equilibrium constant was about 0.97,the reaction was close to thermodynamic equilibrium.（4）To remove free glycerin,the crude biodiesel from the transesterification of Jatropha oil catalyzed by solid base was purified with natural bentonite as adsorbent at room temperature.The effects of bentonite dosage and adsorption time on free glycerin removal were investigated.In addition,the storage stability of the two blend fuel samples B5 and B20 were investigated（B5 and B20 respectively from the mixing 5%and 20%biodiesel with conventional diesel,per volume）.The results showed that the purified biodiesel could meet the requirements of the European Standard for biodiesel fuel（EN 14214）with the yield of biodiesel over 96%,under the conditions of a bentonite dosage of 3.0 wt%and 30 min reaction time.Moreover,the two blend fuel samples B5 and B20 could meet the requirements of the Chinese Standard for biodiesel fuel blends B5（GB/T 25199-2014）,and the storage stability test evinced that the physicochemical properties of B5 and B20 samples remained stable even after 30 and 90 days from their preparation. |
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