Study On Liquefaction Of Microalgae And Epoxidation Of Propylene By Supercritical Fluid Technology

Energy and the environment are important to human survival and development. In recent years due to the vanishing of fossil enery and the increasing pollution of fossil fuels,researchers begin to explore the development and utilization of renewable energy and develop the new Green Chemical Technology replacing traditional fossil fuels to reduce and eliminate pollution as well. Supercritical fluid, which is widely used in extraction and reaction, also shows over advantage on dissolving and mass transfering.Supercritical fluid technology is an environmentally friendly and sustainable development new technology. The SCF technology has important practical significance in development of green chemical technology and renewable sources of energy. The SCF technology actualises the idea of green chemistry in liquefaction of microalgae and epoxidation of propylene reaction. Microalgae biomass, as a renewable energy through liquefaction, can be turned into bio-oil, reducing consumption and reliance on fossil fuels. The SCF technology can expand the application in the development of biomass. The SCF technology applying in epoxidation of propylene can improve the reaction conversion and selectivity and reduce energy consumption and environmental pollution.Direct liquefaction of microalgae Dunaliella tertiolecta in water under the conditions of supercritical and subsupercritical fluid was carried out in an autoclave. Essential component for two kinds of Dunaliella tertiolecta (dry powder and residue) has been analyzed. The effects of reaction temperature, reaction time, the catalyzer, ratio of material to solution and reaction pressure on the liquefaction were investigated. The results showed that the suitable conditions are reaction temperature 360℃, reaction time 60 minutes, the concentration of catalyzer K2CO3 2.5%. Under these conditions the liquefaction yield reached 89.37% and the yield of bio-oil 29.04%.The liquefaction productions and residue were tested by FTIR,GC-MS,SEM.The results showed that the final liquefaction products were complex mixture of organic acid, ester and ketone.The reaction of propylene with H2O2 catalyzed by TS-1 to prepare propylene oxide was carried out in an autoclave. The phase behavior of supercritical fluid was first studied and then the impact of major factors in hydrogen peroxide decomposition. Under the reaction system, the experimental also studied of different reaction conditions under supercritical CO2 and methanol solvent in TS-1/H2O2 catalytic system. The optimum reaction conditions were found finally. The results showed that the suitable conditions are under methanol solvent reaction temperature 40℃,the concentration of catalyzer TS-1 0.6%.,reaction time 60 minutes,propylene pressure 0.4Mpa under methanol solvent.Under Supercritical fluid system,the reaction temperature was 33.7℃(supercritical and near critical temperature),the reaction pressure was 7.58Mpa(near critical pressure and critical pressure range. propylene ), propylene pressure 0.65Mpa, reaction time 45min, cosolvent molality 4%.Under above conditions, the reaction conversion rate was 98%, selectivity 96%, yield 94%, compared with the traditional conditions, the yield increased by 20%.A preliminary study on the catalytic effect of different size of TS-1.Under these conditions show bad catalytic effect of the large particles. The study shows that hydrogen peroxide concentration affect the catalytic effect of large particles and need to further optimize the process conditions.