Process for the preparation of bio-diesel

Abstract

A process is disclosed for the preparation of biodiesel, whereby oil is subjected to catalytical transesterification, settling, separation, bubble washing and micro filtration at controlled conditions of temperature and turbulence. The process enables production of high quality fuel, termed as biodisel, within a period of as low as 50 hrs. The fuel can be used without blending with any conventional fuel.

1 . An improved process for the preparation of bio-diesel, which comprises 
 i) heating oil having by specific gravity in the range of 0.85-0.96 and iodine value not exceeding 208, to a temperature not exceeding 120° C. for not less than 2 hrs followed by transesterification with 8 to 42% w/w, of alcohol of general formula R-OH, where R represents (C n H 2n+1 ), n being any integer between 1 and 5, in presence of not more than 0.55% w/w, of a catalyst, at a temperature higher than the boiling point of the alcohol but not exceeding 215° C. for a period of not less than 30 minutes under continuous turbulent conditions to obtain a mixture of ester and glycerol,    ii) Subjecting the mixture, as formed in step (i) to separation of the esterified oil for a period of not less than 4 hrs followed by purification for a period of not less than 8 hrs. and repeating the process of separation as well as purification in succession for not less than three times to obtain biodiesel.    
     
     
         2 . A process, as claimed in  claim 1  wherein the oil is selected from ricebran oil, cottonseed oil , soybean oil, sunflower oil , castor oil, coconut oil.  
     
     
         3 . A process, as claimed in  claim 1 , wherein the alcohol is selected from methanol, ethanol, n-propanol, n-butanol, and n-pentanol  
     
     
         4 . A process, as claimed in  claim 1  wherein the catalyst is selected from sodium hydroxide, potassium hydroxide.  
     
     
         5 . A process, as claimed in  claim 1  wherein the esterified oil is separated by decanting, centrifuging, gravity separation, settling, either alone or in any combination.  
     
     
         6 . A process, as claimed in  claim 1  wherein the purification of the mixture is by bubble washing involving bubble size of 1-3 mm, micro filtration with not less than 5 micron filter, centrifuging, either alone or in any combination.  
     
     
         7 . A process, as claimed in  claim 1  wherein the Reynolds number (N Re ) for maintaining turbulence is adjusted at not less than 4000 irrespective of the type of reactor.