Research On The Preparation Of Liquid Fuel By Catalytic Liquefaction Of Macroalgae

The rapid development of the world economy benefits from the utilization of traditional fossil fuels.However,these non-renewable resources are becoming exhausting.In addition,the combustion of fossil fuels produces large amounts of air pollutants and releases greenhouse gases,which lead to environmental pollution.More importantly,they are environmentally friendly and renewable,and are considered as promising alternative energy to solve the energy crisis.In recent years,as a kind of liquid bio-fuel,the liquid fuel obtained from algae has attracted much attention due to their potential applications in solving the serious threat of global warming on human beings.The compositions and properties of the bio-oil produced by different transformation methods are different.In this paper,Enteromorpha prolifera was used as raw material to prepare two kinds of bio-oil by deoxy-liquefaction and hydrothermal liquefaction,respectively.Elemental analysis and GC-MS characterizations were carried out of liquid fuels.The results showed that the oxygen content and high heating value of the bio-oils obtained by deoxy-liquefaction and hydrothermal liquefaction are 6.25%,10.29%and40.84 MJ/kg,37.65 MJ/kg,respectively.It is clear that the former possesses the lower oxygen content and the higher heating value.Therefore,deoxy-liquefaction technology is more suitable for the preparation of high-quality liquid fuel from macroalgae.The quality of the bio-oil can be improved by adding appropriate catalysts.In this work,ZSM-5 and MCM-41 zeolites were modified by the metals of Ni,Mo and Ni Mo,respectively and then they were used as catalysts during the liquefaction of Enteromorpha prolifera.The structures and properties of the catalysts were characterized by SEM,BET,FTIR,XRD and NH₃-TPD.The FTIR and GC-MS analysis results of the obtained liquid oils revealed that the catalysts can reduce the oxygen and nitrogen contents,and improve the heating value of the bio-oil.Furthermore,when using Ni Mo/ZSM-5 as the catalyst,we obtained the highest heating value(43.66 MJ/kg)and highest content of hydrocarbons(26.76%)including alkanes and aromatics.In the process of macroalgae liquefaction,the use of micro-mesoporous composite zeolite catalysts can perform the complementary advantages and synergy of microporous and mesoporous zeolites.ZSM-5/MCM-41 composite zeolite catalyst was synthesized and modified by Fe,Cu,Co,Ni,Mo and Ni Mo,respectively and then they were used as catalysts during the liquefaction of Enteromorpha prolifera.The structures and properties of the catalysts were characterized.The results of the composition analysis results showed that the obtained bio-oil using Ni Mo/ZSM-5/MCM-41 catalyst had the lowest oxygen content(2.22%)and highest heating value(45.37 MJ/kg).