Synthesis Of L-glutamate Ionic Liquids And Its Catalytic Fatty Acid Preparation Of Biodiesel

Biodiesel is a type of energy that conforms to the"carbon neutral"strategy.Compared with traditional petrochemical diesel,biodiesel is green,renewable and other advantages.Traditional biodiesel production methods mostly use acid-base catalysts,which not only have many by-products,but also cause equipment wear due to catalyst corrosion.New biodiesel production technology is also limited by technical immaturity.Amino acid ionic liquid is the general name of salt synthesized based on natural amino acids.It overcomes the disadvantage of environmental risk of traditional ionic liquid,and has been applied in many fields,and is also suitable for catalytic preparation of biodiesel.This study aiming at the shortcomings of the existing catalyst,using a batch of acidic amino acid ionic liquid amino acid synthesis,and select a has the best effect of catalytic esterification of[L-Glu][HSO₄],explores its conventional and ultrasonic assisted method under catalytic esterification of fatty acid esterification reaction process conditions and oleic acid catalyzed esterification reaction kinetics.The main conclusions are as follows:（1）A total of 15 amino acid ionic liquids were synthesized.By catalyzing oleic acid esterification,[L-Glu][HSO₄]ionic liquid has the best catalytic effect of esterification reaction.The experimental results show that the stronger the acid of amino acid ionic liquid,the higher the conversion rate of catalytic esterification reaction.（2）Under the conventional esterification method,the optimum conditions for oleic acid,stearic acid and lauric acid catalyzed by[L-Glu][HSO₄]ionic liquid were obtained.Under the optimum conditions,the conversion rate of oleic acid,stearic acid and lauric acid could reach 96.03%,96.48%and 97.87%respectively.[L-Glu][HSO4]ionic liquid was repeated 5 times in the above reactions,and its catalytic performance did not decrease obviously.（3）Under the set ultrasonic（35k Hz,450W）auxiliary conditions,the conversion rates of[L-Glu][HSO₄]ionic liquid catalyzed oleic acid,stearic acid and lauric acid under optimum conditions were 85.84%,78.67%and 92.63%,respectively.Compared with the same catalyst dosage,methanol dosage and temperature,the conversion rate of the ultrasonic-assisted method is slightly higher than that of the conventional method.Analysis of the reason may be that the presence of water and glass medium in the conical flask affects the propagation of ultrasonic energy in the ultrasonic-assisted esterification reaction,so that the advantages of ultrasonic-assisted esterification cannot be fully exerted,and the esterification effect beyond the conventional method cannot be obtained.（4）Under the optimization of response surface methodology,the reaction conditions of[L-Glu][HSO₄]ionic liquid catalyzing oleic acid conversion are as follows:ionic liquid volume was 15%,n _methanol∶n _{oleic acid} was 11∶1,reaction temperature was 70℃,reaction time was 12h.Under these conditions,the predicted value of oleic acid conversion was 96.66%,and the actual conversion was 97.02%.The model determined that reaction temperature had the greatest influence on oleic acid conversion,and the other factors were n _methanol∶n _{oleic acid},reaction time and ionic liquid dosage.The reaction activation energy and frequency factor of oleic acid esterification catalyzed by[L-Glu][HSO₄]ionic liquid are 29.65 k J·mol^-1 and7.88×10~2 min^-1,respectively.