Rapeseed Oil Supercritical Preparation Of Biodiesel

With the growing shortage of fossil energy and the living environment of mankind gradually deteriorate,"bio-diesel" as one of the substitute for fossil energy,as the alternative fuel of diesel engines is now being more and more attention.Biodiesel is composed by the fatty acid methyl esters that be produced through transesterification reaction from animal fat or plant oil.As a non-toxic,biodegradable and renewable alternative fuel for engines,it has been more and more attention.The study of many foreign showed that.the characteristics of biodiesel are very similar to ordinary diesel.Therefore biodiesel can be used directly in diesel engines,without changing diesel engine the structure.Biodiesel is normally provided by the animal and plant oil that through ester-exchange reaction with methanol,commonly used alkaline,acid or lipase as catalyst.Currently,the producted methods of biodiesel mainly through transesterification reaction be catalyzed by alkali such as KOH,NaOH,and others,although the technologies of the method is very mature,but there are still same shortcomings,as separation difficulties because of the saponification reaction,must be washed and there would be more wastewater and the higher costs etc.The new method that supercritical transesterification can overcome these shortcomings,but that need higher temperature and higher pressure.In response to the problems,and utilize the characteristic that methanol is not only raw materials,but also could be regarded as a supercritical solvent characteristics in the supercritical methanol ester-exchange reaction for biodiesel ideas:the study use orthogonal test methods in the supercritical transesterification by supercritical methanol and rapeseed oil on the conditions optimized screening test.Study select Yunnan rapeseed oil as raw material,inspected transesterification reaction conditions such as reaction temperature,reaction pressure,reaction time,the molar ratio of methanol and oil on the impact to the response;the degree of order of impact on the main impact factors on the transformed law were:reaction temperature＞the molar ratio of methanol and oil＞reaction pressure＞reaction time;the best reaction conditions of the study was:280℃,13 MPa,30 minutes,alcohol,and 42:1;then adopted the single factor test methods to further define various reaction conditions on rapeseed oil in supercritical methanol transesterification reaction of the specific impact,the results should:the best reaction temperature is 340℃,the best reaction pressure is 12MPa,the optimal reaction time 8 mins;ratio of methanol to oil is 42:1;Finally,according the GB testing methods and requirements use GC and GC-MS methods on the test product performance tests:the physical and chemical performance products reached S500 standards;the main composition of the production are Methyl esters.