| At present,the first generation biodiesel?fatty acid methyl ester,FAME?is not well accepted by the market due to its competitive counterpart from cheap crude oil,leading to excess production of FAME.So it is urgent to convert FAME to other value-added chemicals.This dissertation is aimed to investgate the durability of NiMo/NiAl2O4 catalysts in the hydrogenation of FAME to bio-alkanes,as well as the reaction thermodynamics and macrokinetics,in order to obtain fundamental data used for further industrial application.Experimental results showed that the FAME conversion and product selectivity were higher than 98% and 97%,respectively,after 1010 h reaction period,suggesting NiMo/NiAl2O4 catalyst was stable enough for the hydrogenation of FAME to bio-alkanns.However,heavy products were detected due to the polymerization of C=C double bonds in FAME.A new process combining hydrogenation of FAME to the saturated esters in an autoclave and the subsequent hydrodeoxygenation to bio-alkanes was proposed to avoid the undesired polymerization of FAME.The optimized conditions for the hydrogenation of double C=C bonds over NiAl catalyst contains reaction temperature of 190?,hydrogen pressure of 2.0 MPa,catalyst mass content of 2%,and reaction time of 20 min.Under such conditons,both the FAME conversion and product selectivities were above 99.9%,with the reaction heat estimated to be 387.34kJ·kg-1.Analysis results showed that reaction orders for FAME concentrations,H2 pressure and catalyst weight percent were 1.0,0.81 and 2.0,respectively.Further hydrodeoxygenation of the saturated FAME to bio-alkanes was conducted under conditions of 380?,2 MPa H2,0.5 h-1 and volume ratio of H2/esters at 1000.Reaction thermodynamics and reaction parthway for the hydrodeoxygenation of FAME were simply discussed according to the effects of temperature and space velocity on the product distribution.The estimated reaction heat was 896.5-940.3 kJ·kg-1. |
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