Catalytic Hydrodeoxygenation And Hydrocracking Of Microalgae Biodiesel To Produce Hydrocarbon Fuels Over Bifunctional Catalysts

The development of green renewable bio-jet fuel alternative to traditional fossil jet fuel can effectively reduce the carbon dioxide emissions in the air transport industry.Many airlines both at home and abroad have started to test bio-jet fuel such as cooking oil and palm oil.However,the shortage of bulk oil-based raw materials is a key bottleneck that limits the development of the bio-jet fuel industry.Microalgae is an ideal raw material for bio-jet fuel with the advantages of fast growth rate and high oil content.In this paper,the microalgae biodiesel was catalyzed through hydrodeoxygenation and hydrocracking to produce hydrocarbon fuels within the jet fuel range over nickel-based gradient mesoporous zeolites as bifunctional catalysts and the sulfonation was used to enhance the catalyst acidity and increase algae-based hydrocarbon fuels conversion rate and compositional quality.The strong acidity(about 0.41mmol/g)appeared in the bifunctional catalysts when nickel was used as a deoxidation center on zeolites,which effectively enhanced the acid strength.The mesopore size of Ni-based gradient mesoporous Y zeolites after loading is concentrated between 10 to 20nm.The crystallinity of 10wt%metallic nickel particles loaded on zeolites is intact.Compared with the catalyst without nickel,the algae oil can be efficiently catalyzed through hydrodeoxygenation and hydrocracking to obtain the hydrocarbon fuels within the jet fuel range with high alkane content and low aromatic content.Directional control the hydrodeoxygenation and hydrocracking process of algae oil to increase the isoparaffin content in the hydrocarbon products within the jet fuel range and make the carbon chain distribution more uniform.Optimize the key parameters such as the reaction temperature and algae.oil flow rate,the selectivity of algae oil conversion to hydrocarbon within the jet fuel range was increased from 29.80%to 58.18%at the optimal reaction temperature of 275 ? and algae oil flow rate of 0.02ml/min,the isomerization ratio of paraffin in products increased from 15.38%to 46.40%,and the content of aromatics reached 11.45%and the content of naphthenes and olefins reached 5.95%and 1.54%respectively,which significantly improved the composition of hydrocarbon products within the jet fuel range quality.Sulfonation was used to enhance the acidity of nickel-based gradient mesoporous zeolites for the first time,which increased the conversion rate of microalgae biodiesel to hydrocarbon fuels.Sulfonated zeolites appeared-SO3H sulfonic acid group,the medium strong acid content increased from 0.31mmol/g to 1.21mmol/g.With the increase of sulfonation agent content,the conversion rate of microalgae biodiesel to hydrocarbon fuels within the jet fuel range over sulfonated bifunctional catalysts increased first and then decreased.When the sulfonation agent content loaded on the gradient mesoporous zeolites achieve the optimum content of 0.38ml/g,the conversion rate of microalgae biodiesel to hydrocarbon fuels increased from 82.13%to 99.71%,paraffin selectivity increased from 31.21%to 52.34%,aromatics selectivity decreased from 13.46%to 0.57%,thereby increasing algae-based hydrocarbon fuels conversion rate and improving the composition of hydrocarbon fuels within the jet fuel range.