ZSM-5 Supported Catalyst Catalyzes Transesterification Of Microalgae Oil To Produce Biodiesel

With the rapid development of science and technology,human footprint has spread all over the world.Vehicles driven by fossil fuels,such as automobiles,ships and planes,emit a lot of carbon monoxide,hydrocarbons,nitrogen oxides and other exhaust gases,which have a serious impact on the climate and environment.At the same time,the limited reserves of oil and coal also lead to the rising price of fossil fuels.With the development of energy revolution,many countries are actively seeking clean renewable and new energy.Biodiesel is a typical representative of biomass energy,which is composed of long-chain monoalkyl esters.It has the advantages of non-toxic,sustainable and biodegradable,and can be used as a substitute for petrochemical diesel.The research and development of heterogeneous catalysts for the preparation of biodiesel by alkali catalyzed transesterification will help to provide strong support for the industrial continuous production of biodiesel.The specific research contents are as follows:（1）Spirulina platensis oil was extracted by chloroform-methanol method.The oil extraction rate was 27.6%,and the acid value was 0.95 mg KOH/g,which could be used for alkali-catalyzed transesterification reaction.The fatty acid composition of Spirulina oil was determined by gas chromatography-mass spectrometry.The physicochemical properties of biodiesel met GB and EN fuel standards.It had the similar structure with petrochemical diesel,and can replace or mix with petrochemical diesel for engine fuel.（2）MgO/ZSM-5 catalyst was synthesized from magnesium acetate and ZSM-5 by impregnation-ultrasonic method.The physical and chemical properties of the catalyst were characterized and analyzed by TG,XRD,CO₂-TPD,SEM-EDS,FTIR and BET.Compared with the catalyst without ultrasonic treatment,S-MgO/ZSM-5-650 prepared by impregnation-ultrasonic method had the stable structure,strongest basicity and better morphology.The cavitation effect of ultrasonic promoted the particle size of active phase to be small and uniform.（3）The reaction conditions of Spirulina biodiesel were optimized by Taguchi method.The optimal conditions were determined by using SNR and ANOVA,that is,the molar ratio of ethanol to oil was 15/1,the concentration of catalyst was 3 wt%,the reaction temperature was 75 ^oC,the reaction time was 1 h,and the yield of biodiesel could reach92.1%.The yield of the catalyst remained above 85%after 5 times of use,indicating that the supported catalyst prepared by impregnation-ultrasonic method had excellent stability.（4）The kinetic and thermodynamic studies showed that the transesterification followed pseudo first-order reaction with activation energy of 49.67 k J/mol,which was a non spontaneous endothermic reaction.The engineering economic analysis showed that the catalyst can effectively reduce the production cost of biodiesel,and the cost of the third generation biodiesel was close to or slightly higher than that of the first generation and the second generation.The research of green chemistry showed that the production of biodiesel by alkali catalyzed transesterification had high conversion and environmental protection.Therefore,the synthesis of supported catalyst provided a feasible choice for reducing the cost of industrial production and realizing efficient continuous clean production.