Catalytic Pyrolysis Of Soybean Oil To Produce Hydrocarbon Fuels

Under the double pressures of energy and environmental crisis,the full use of triglycerides to produce hydrocarbon fuels is increasingly concerned by researchers.Catalytic pyrolysis of triglycerides is considered to be one of the most promising ways to proudce liquid biofuel.In this paper,the pyrolysis of soybean oil was conducted in a self-made fixed bed reactor.The effects of temperature and feed rate on the yield of the products were investigated by using 35 wt.%A/C as the catalyst.The appropriate pyrolysis temperature was 480 ?,feed rate was 0.4 ml/min.The yield of the pyrolysis liquid was 74.87% under this condition.The effects of seven kinds of catalyst types,such as Blank,?-Al₂O₃,10 wt.%A/C,20 wt.%A/C,35 wt.%A/C,50 wt.%A/C and CaO were investigated.It showed that,with the increase of the mechanical mixing ratio of ?-Al₂O₃ in CaO,the yield of pyrolytic oil increased firstly,and then decreased,and the yield of oxygenated compounds decreased.?-Al₂O₃ showed good dehydration ability in the reaction process.When 35 wt.%A/C participated in the reaction,the yield of pyrolytic oil reached a maximum of 70.0%.The chemical composition and the fuel performance of the pyrolytic oil were analyzed.It was found that appropriate proportion of ?-Al₂O₃/CaO can optimize the carbon chain distribution and promote the increase of hydrocarbon contents,further improve the heated value of the pyrolytic oil.It can also reduce the acid value of the pyrolytic oil because CaO showed good decarboxylation performance,while the kinematic viscosity and density also reduced.Taking into account all factors,35 wt.%A/C was determined to be a relatively preferred ratio.CaO have been selected as catalyst for the catalytic pyrolysis of soybean oil in a self-made scale up reactor.The effects of carrier gas flow rate,temperature,amount of catalyst and feed duration on the composition and yield of the pyrolytic liquid were investigated when the feed rate was 1.0 ml/min.The appropriate pyrolysis temperature was 450 ?,WHSV = 0.38 h^-1,and without carrier gas.Under this condition,the yield of pyrolytic liquid was 55.8% and the content of hydrocarbon was 81.4%,which included 65.3% alkane and olefin.Besides,the contents of less than C8 and C9^C16 were 46.9% and 43.7% respectively.The input quantity was used to investigate the duration of CaO in the reactor.It was found that CaO was not suitable for continuous reaction in the scale up reactor.The fuel performance of the pyrolysis liquid obtained under the optimized conditions was determined.The specific parameters were as follows: density 849 kg/m³,kinematic viscosity 3.9 mm²/s,heated value 43.9 MJ/kg,acid value 3.1 mgKOH/g.Acid value of pyrolysis liquid was slightly higher than the biodiesel,other indicators can reach the standard of 0#diesel.The catalytic pyrolytic characteristics of soybean oil were investigated using thermogravimetry analysis.The results showed that CaO and ?-Al₂O₃ can expand the reaction temperature range and reduce the maximum pyrolysis rate.35 wt.% A/C to participate in the reaction is similar to CaO.Compared with the thermal pyrolysis of soybean oil,CaO and ?-Al₂O₃ can effectively reduce the activation energy.?-Al₂O₃ can significantly reduce the main reaction temperature interval,and 35 wt.%A/C can cause two main reaction zones.In this case,the reaction is more likely to occur.The mechanism of catalytic pyrolysis of triglycerides is complex.It includes the preliminary pyrolysis,decarboxylation and decarbonylation of triglycerides,CaO to participate in the reaction,Diels-Alder reaction to form aromatic hydrocarbons,and free radical cyclization.