Synthesis Of Binary Solid Alkaline Catalysts And Its Catalytic Performance For Biodiesel Production

Biodiesel is the compound of various kinds of chain fatty acid methyl?ethyl?esters,with the merits of low toxicity,low cost,low sulfur,high cetane index and so on,which is the alternative of oil fuel.In addition,solid catalysts have the advantages of high catalytic activity,mild reaction condition and convenient recyclability.With the development of biodiesel preparation,catalyst design,catalyst selection and the range of application became the focus of research.In this work,we prepared four binary basic solid catalysts and made a detailed analysis in microstructures,acid-resistance,water-resistance,reusability and catalytic activity.First,the method of sol-gel was applied to preparing SiO₂@Ca O alkaline catalyst,choosing polystyrene as hard template and P123 as soft template to control the microstructure.Furthermore,the obtained solid catalyst was applied to the transesterification of soybean and methanol.Also,the nano-solid base catalyst was analyzed by means of X-ray diffraction?XRD?,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,CO₂-TPD and N₂ absorption-desorption?BET?,proving that SiO₂@CaO alkaline catalyst had an ordered morphology and core-shell structure.In addition,ratio of m?SiO₂?:m?CaO?1:5,reaction temperature 70 ^oC,catalyst dosage 2.0 wt.%and ratio of n?oil?:n?methanol?1:12were the best reaction condition,and the biodiesel yield can reach 95.6%.Then,the methods of precipitation-impregnation and calcination were applied to preparing chestnut involucre-shaped MgO@CaO alkaline catalyst,choosing CH₃CH₂OH and H₂O mixed solution as solvent and Mg?OH?₂ as support,which was made by hydrothermal method.Furthermore,the obtained solid catalyst was applied to the reaction of soybean oil and methanol,evaluating its performance.Catalyst calcination temperature 700 ^oC,calcination time 3 h,reaction temperature 70 ^oC,catalyst dosage 1.5 wt.%and ratio of n?oil?:n?methanol?1:15 were found to be the best reaction condition,and the biodiesel yield can reach 98.8%.In addition,the water-resistance and reusability of MgO@CaO alkaline catalyst were studied,as a result,the MgO@CaO alkaline catalyst performed excellent stable and reusability.All of these would make MgO@CaO alkaline catalyst to be a good choice for biodiesel industrial production.Furthermore,the methods of sol-gel and calcination were used to prepare magnetic core??-Fe₂O₃ and hematite Fe₂O₃?,which were applied to supporting CaO,preparing two heterogeneous catalysts as?-Fe₂O₃@CaO and hematite Fe₂O₃@CaO.In addition,the magnetism and catalytic performance of the two prepared heterogeneous catalysts were investigated,as a comparison,?-Fe₂O₃@CaO showed better than hematite Fe₂O₃@CaO in both magnetism and alkalinity.Under the condition of 4 mg KOH/g acid value,?-Fe₂O₃@CaO still possessed high activity.Moreover,the biodiesel yield still could arrive at 80.2%after 4th used.Finally,my article used banana peel as raw resource to prepare K₂O-KCl alkaline catalyst with the calcination temperature of 600 ^oC.During the process of calcination,the decomposition of carbon fiber protected K₂O-KCl alkaline catalyst from aggregation,so it showed a better dispersion than which was prepared by simple physical mixing.In addition,under the optimized reaction conditions of catalyst dosage 1.5 wt.%,ratio of n?oil?:n?methanol?1:15,reaction time 1 h and reaction temperature 70 ^oC,biodiesel yield could achieve 95.1%.Furthermore,the prepared alkaline catalyst perfected well in both water-resistance and recyclability.