I was chatting today with a chemical engineer who happened to write his final thesis (the paper you write in order to graduate) on the methyl esters and transesterifications. As a chemical engineer, he studied che kinetics of the reaction and the reaction speeds, and he designed a production facility for a continuous process. He made all sorts of tests using IR spectrography at different points of the reaction, and made a very thorough work from the "chemical point of view". He did not want to show me his thesis (maybe he was afraid of me copying methods still not patented), but he did give me some hints and opinions, which I try to summarize here, and which you might want to have a look at: (This guy used soy oil)
.- Strange enough, he pointed out that some "thorough investigations" were not 100% right, but he didn«t say where they were wrong: he just added "do the experimentation yourself, and you«ll see" .- He said that 50¼C for the reaction was waaay too much. He said he carried out his continuous process at room temperature. Besides this, he pointed out that the glycerin was very easily decomposed into acrolein and things like that, which make it dark brown. I was so curious that just now, when I got home, I made a 100ml batch at room temp (now around 18¼C), and mixed for only 15 minutes. This guy said that they had achieved a 98% conversion after this time period. Now I«ve let it settle, and I can see after about an hour settling that the glycerin DOES show up much clearer (pure glyc is transparent). He also said that in his continuous process he had designed a three stage evaporator to remove the water from it, after distilling it to get out the MeOH (I suppose he«d do this under vacuum, so as not to heat the glyc and turn it into the mentioned brown acrolein). I found this point most interesting. .- He mentioned they used sulphuric acid (say, 4ml per liter of WVO) to "cut" the reaction and stop the NaOH (this forms sodium sulphate, Na2SO4, which is washed with the water). I said I added some drops of vinegar in the washing stage and he almost whent crazy: he said tha any ammount of vinegar capable of modifying pH would produce great problems with the injectors. He said motors are very sensitive to those acid conditions. .- He also pointed out that I should remove the sulphates (which came from the sulphuric acid / lye reaction) from the glycerin, and added that the glycerin was full of impurities: sulphates, MeOH, water... .- He also added that boiling off the MeOH was not a very eco-friendly thing to do, and that you«d never be able to boil off 100% of it (eve with a distillation column) .- He said a continuous centrifugue was not har to get, but reaction velocities had to be carefully measured when designing a continuous process. He fancied this method and said that settling the BD was not a good option, specially after vigorous mixing, which always (according to him) brought emulsification problems of some kind. .- Regarding the fact I am an environmental engineer, he pointed out the washing stages use a damn great ammount of water (I can«t recall having heard of an alternative to this from him). Also, than no reaction is 100% efficient and that if I was to measure exhaust gases, then I *should* be checking for unburnt traces of methanol, which could produce nasty emissions. Everything he said sounded most interesting, but presented me with a whole new set of questions to be answered. I«m very eager to hear the opinion of those with experience in BD making, specially those who use it regularly in their cars. Best to you all, Christian [Non-text portions of this message have been removed] ------------------------ Yahoo! Groups Sponsor ---------------------~--> Buy Stock for $4 and no minimums. FREE Money 2002. http://us.click.yahoo.com/orkH0C/n97DAA/Ey.GAA/FGYolB/TM ---------------------------------------------------------------------~-> Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send "unsubscribe" messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
