| With the increasing global exploitation of petroleum which is a non-renewable resource and the aggravating air pollution resulted from its burning, searching for renewable and environmental friendly alternative energies is an effective method to solve the energy crisis currently. As biodiesel burns almost the same as fossil diesel and can be reproduced as well as environmental friendly, it is an excellent alternative energy. However the large-scale production of biodiesel is mainly restricted by its high production cost severely. The cheap feedstocks such as wasted cooking oil and hogwash oil usually contain a good deal of free fatty acids(FFA). If the feedstocks are not processed, it will result in lower catalyst activity and saponification. Usually the traditional technique adopts acidic catalyst esterification to reduce the acid value of feedstocks containing much FFA and uses transesterification to produce the biodiesel later. But common homogenous acid catalytic reactions have problems such as slow reaction speed, equipment corrosion and difficulty in separation operation. However solid acid catalyst is a very good substitution for its high catalytic activity, easy separation and recycle, so it is becoming the popular issues.The cheap plant oil Jatropha curcas L.oil was choosed as feedstock in this thesis whose goal reaction was esterification. Two kinds of low cost acid catalysis were made which were ST-NaB and SZ-NaB and a detailed study on the influence factors of the preparation condition was performed including the calcination temperature, calcination duration, catalyst mix proportion, concentration of acid impregnating solution. Meanwhile, the influence factors of the esterification of Jatropha Curcas oil were also studied, such as reaction temperature, molar ratio of methanol to oil, catalyst loading and reaction duration. Experimental investigation showed that the best condition to prepare solid acid catalyst SZ-NaB was the mass ratio of bentonite to ZrO2being54.2%, concentration of impregnating H2SO4being lmol-L-1, calcining3hours at550℃. And the optimum esterification condition was reaction temperature being150℃,10%wt. ST-NaB with a molar ratio of methanol to oil20:1and a4h reaction duration. The highest conversion rate was94.1%. While researches manifested that calcination temperature affected the catalyst activity more severely than calcination duration when preparing the ST-NaB solid acid catalyst. And the best esterification preparation condition of SZ-NaB was calcination at550℃for3hours. The best reaction parameters were170℃,5%wt. SZ-NaB, with a molar ratio of methanol to oil30:1and5h reaction duration. The highest conversion was95.1%.Using SEM, XRD, BET determination technique, it showed that the ST-NaB solid acid catalyst had holey loosen surface, with a grain diameter being2-10um and specific surface area being16.543m2/g. With higher calcination temperature, the ingredient of SO42-gradually degenerated leading to a declined catalyzing ability. Comparatively speaking, the ST-NaB catalyst had the same surface properties, whose pecific surface area was101.483m2/g. As the calcination temperature increased, TiO2crystallization was enhanced and the catalytic ability decreased.Both of the ST-NaB and SZ-NaB solid acid catalysts could be recycled several times. With the reaction times increased, the acid ingredients dissoluted into the reaction system which was mainly responsible for the degeneration of catalytic ability. During the reusing process of the catalysts, the organic compounds absorbed on their surface and the reaction holes were obstructed which influences the catalytic ability. When the catalysts lost their catalysis, calcination directly or after acidified could recovery the catalyst activity effectively. |
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