Hydrodeoxygenation Of Biodiesel To Hydrocarbon Liquid Fuels

As the first generation of biodiesel,fatty acid methyl esters have several advantages,such as high cetane number,high flash point and it's safe to use.It is a clean and environmentally friendly renewable energy source.However,the utilization of first generation biodiesel affected by its high oxygen content,low calorific value,easy to make the engine fouling and other shortcomings.Therefore,people gradually divert attention to the second generation biodiesel that contains hydrocarbon as the main component.At present,the second-generation biodiesel is mainly prepared by catalytically hydrogenating oils,long-chain fatty acids or fatty acid methyl esters to obtain hydrocarbon components which have the similar structure with petrodiesel.In this paper,biodiesel was used as raw material to carry out hydrogenation reaction.Through comparison of different catalysts and reaction conditions,suitable catalysts and reaction conditions were selected that the yield of second generation biodiesel components obtained by hydrodeoxygenation was higher.The results of the study were as follows:?1?The different mixing ratios of ZSM-5 and Al₂O₃ blending catalyst ZSM-5-Al₂O₃ and acid carrier catalyst SAPO-11 were prepared and characterized by XRD,BET,and SEM.The results showed that the SAPO-11 catalyst was a pure crystalline phase with the microporous structure;ZSM-5-Al₂O₃ catalyst have a mixed peak of ZSM-5 and Al₂O₃ with only a small amount of microporous structure.?2?Using biodiesel as raw material and hydrodeoxygenation with Pt/10%ZSM-5-Al₂O₃ as catalyst,the products'mass fractions of gas,liquid and solid were analyzed and the composition of each phase was analyzed in detail.The effects of reaction temperature,pressure,LHSV and hydrogen oil volume ratio on the product were investigated that taken the yield of the second generation biodiesel as an index.And the possible reasons were analyzed.The results showed that with the increase of reaction temperature,pressure and hydrogen-oil volume ratio,the yield of second-generation biodiesel increased in the first stage and then decreased;with the increase of LHSV,the yield of second-generation biodiesel has been reduced.The optimal reaction conditions were obtained as follows:reaction temperature of 340?,pressure of 2 MPa,LHSV of 0.5 h^-1 and hydrogen-oil ratio of 1000.Under the optimum conditions,The yield of second-generation biodiesel reached 80.22%and the ratio of the decarboxylation/hydrodeoxygenation was 3.17.?3?The bifunctional catalyst Pt/ZSM-5-Al₂O₃ with different mixing ratio was used in the hydrodeoxygenation reaction of biodiesel to study the influence of the mixing ratio of ZSM-5 and Al₂O₃ on hydrodeoxygenation products.The results showed that when the mixing ratio of ZSM-5 is 10%,the mass yield of diesel components is higher,the light components of cracked gas in the product is lower and the higher catalytic activity can be maintained for a longer time.?4?The composition of the solid product on the Pt/10%ZSM-5-Al₂O₃ catalyst surface was analyzed experimentally.The relationship between the reaction time and the mass of the solid product was also investigated.The results showed that with the increase of the reaction time,the mass of the solid product was not increased obviously.?5?The Pt/SAPO-11 catalyst performs hydrodeoxygenation and isomerization of biodiesel.The optimal reaction conditions were obtained as follows:reaction temperature 360?,pressure 1MPa and LHSV 1 h^-1.Under the optimum conditions,the mass fraction of diesel in liquid product was more than 94%and the isomerization rate of product was 67.29%.