Research On The Synthetical Rules Of Biodiesel Catalyzed By Solid Alkali Catalysts

As supply of fossil fuels is limited whilst energy demand continues to rise, research is increasingly directed towards alternative renewable fuels. Biodiesel, consisting of fatty acids produced by transesterification of vegetable oils or animal fats with methanol, has attracted considerable recent attention because of its environmental benefits and the fact that it comes from renewable resources.The preparing methods of biodiesel can be divided into four sorts as following: direct mix, decomposition under high temperature, tiny emulsification and transesterification. Currently, transesterification has been widely used in industrial biodiesel production. And more recent research on transesterification has focused on the use of solid base catalysts. Being a heterogeneous basic catalyst, it has the advantages of high activity, high selectivity, facile reaction condition, an easy phase separation, cycle using and so on. At present, a number of studies of the preparation of biodiesel by the transesterification of vegetables oils have been reported using a variety of solid base catalysts, but these processes have ilka disadvantages.In this thesis, new-style solid base catalysts were designed and prepared. Via contrast and filtration, mesoporous MCM-41 which has well-defined pore size and shape, high specific surface and large adsorption capability was chosen as carrier of solid base catalysts. Because there was no catalytic activity center on mesoporous MCM-41, it was modified in two ways: impregnation and chemical grafting. Catalytic activity centers were produced while alkali metals and organic amine were introduced into the inside surface of MCM-41.Modified mesoporous MCM-41 was characterized by XRD, SEM, TEM, FTIR, TGA, CO2-TPD. It indicated that silica materials have been modified with alkali metals and organic amine, maintain hexagonal phase and obtain a number of strong alkali sites. Their catalytic activity of transesterification to produce biodiesel from soybean oil was investigated. The influence of category of active component, different active component loading, molar ratio of methanol to oil, dosage of solid base catalysts and reaction time on transesterification was studied. Under the following conditions: 8.0 wt% Na2O loading, molar ratio of methanol to oil 16:1, catalyst dosage 3.0 wt%, reaction temperature 130℃and reaction time 2 h, the yield of biodiesel could reach 89.8%. And the kinetics of transesterification between methyl ester and reaction time was analyzed as well. It supplied the theoretic to the optimization and fine control of biodiesel industry.