Study On Catalytic Pyrolysis Of Microalgae To Bio-Oil With MCM-41/Hβ And Its Modified Molecular Sieve Catalyst

Seaweed biomass with high biological productivity has great potential in the resources development. Meanwhile, high-quality bio-oil can generate from the catalytic pyrolysis of seaweed biomass. The investigations on seaweed biomass catalytic pyrolysis are of great theoretical and practical value.In this thesis, the slow pyrolysis characteristics of chlorella were examined by thermogravimetric analyzer. The analyses of TG and DTG curves showed that pyrolysis behavior of chlorella could be divided into four obvious reaction stages. Chlorella pyrolysis temperature was lower than that of conventional biomass such as wood. The pyrolysis reaction kinetic was investigated by Coats-Redfern method, indicating that the most probable mechanism functions of chlorella was second-order reaction model at a given temperature range. The corresponding activation energy E and frequency factor A and imitative straight line equation were obtained by the best mechanism function.Catalytic pyrolysis experiments of chlorella were conducted in a fixed bed reactor using molecular sieves MCM-41and Hβ. The influence of the catalysts on the product distribution, physical property and components of bio-oil were studied. It showed that the catalytic pyrolysis of chlorella with MCM-41increased the yields of hydrocarbons in the bio-oil. HP exhibited deoxygenation and aromatization. It improves the quality of the bio-oil for MCM-41than Hβ as the catalyst in the catalytic pyrolysis of chlorella. Under the optimum pyrolysis process conditions, bio-oil maximum yields is25.67%, the bio-oil calorific value raised31.768MJ·kg-1, the moisture content of the bio-oil is equal to6.531%and the kinematic viscosity reached23.51mm2·s-1. According to the component analysis of chlorella and the GC/MS analysis of catalytic bio-oil, the reaction route for the catalytic pyrolysis of chlorella over MCM-41catalyst was analyzed.Using siliceous mesoporous molecular sieve MCM-41as carrier loaded Al, Zn or Mn by impregnation.XRD, NH3-TPD showed that the addition of Al, Zn and Mn could significantly decrease the order degree of the mesopore structure, while it increased the acidity of molecular sieve catalyst obviously. The influences of the modified catalysts on the pyrolysis behavior of chlorella were researched by the catalytic pyrolysis experiments. The results showed that it was conducive to improve the bio-oil yield by adjusting the content of Al in a certain range. Zn facilitated the dehydrogenation and deoxidization. Mn was conductive to increase the yields of hydrocarbons. The modified catalysts loaded Zn and Mn exhibited significantly denitrification and promoted the decomposition of chlorophyll in chlorella, but they decreased the yield of bio-oil.