Continuous process for producing biodiesel fuel

Abstract

A continuous process for producing biodiesel fuel with a conversion of triglycerides in biodiesel above 99.90% by weight in the transesterification step, which comprises the following steps: a) providing a triglyceride source at a triglyceride concentration above 99.0% by weight; b) subjecting triglycerides to a transesterification reaction with methanol, ethanol, or the mixtures thereof, at a molar ratio of triglycerides:alcohol 1:3-3.5, in the presence of 0.7 to 1.0% by weight of sodium or potassium hydroxide as catalyst, under ultrasonic cavitation conditions in an ultrasonic cavitation reactor with 2 to 8 serial cavitation cells, at a temperature of 45 to 60° C., at a pressure of 1.5 to 2 MPa (15-20 atm) and during a period of time of 15 to 30 seconds; c) recovering the product of step b) and subjecting it to mechanical agitation operation, at a temperature of 45 to 60° C. for a maximum of 10 minutes, up to the completion of the transesterification reaction, thus obtaining a conversion of triglycerides in biodiesel above 99.90% by weight; d) decanting and/or centrifuging the product resulting from step c) to remove glycerin; e) purifying biodiesel obtained in step d) by exchange resins; and f) removing by distillation methanol and water from the product of step e) and recovering the biodiesel fuel thus obtained.

1 . A continuous process for producing biodiesel fuel with a conversion of triglycerides in biodiesel above 99.90% by weight in the transesterification step, wherein it comprises the following steps:
 a) providing a triglyceride source at a triglyceride concentration above 99.0% by weight;   b) subjecting triglycerides to a transesterification reaction with methanol, ethanol, or the mixtures thereof, at a molar ratio of triglycerides:alcohol 1:3-3.5, in the presence of 0.7 to 1.0% by weight of sodium or potassium hydroxide as catalyst, under ultrasonic cavitation conditions in an ultrasonic cavitation reactor with 2 to 8 serial cavitation cells, at a temperature of 45 to 60° C., at a pressure of 1.5 to 2 MPa (15-20 atm) and during a period of time of 15 to 30 seconds;   c) recovering the product of step b) and subjecting it to mechanical agitation operation, at a temperature of 45 to 60° C., for a maximum of 10 minutes, up to the completion of the transesterification reaction, thus obtaining a conversion of triglycerides in biodiesel above 99.90% by weight;   d) decanting and/or centrifuging the product resulting from step c) to remove glycerin;   e) purifying biodiesel obtained in step d) by exchange resins; and   f) removing by distillation methanol and water from the product of step e) and recovering the biodiesel fuel thus obtained.   
     
     
         2 . A process according to  claim 1 , wherein the triglyceride source is a new or used vegetable oil. 
     
     
         3 . A process according to  claim 1 , wherein the triglyceride source is a new or used animal fat. 
     
     
         4 . A process according to  claim 1 , wherein in the transesterification step, 0.95% by weight of sodium hydroxide is used, temperature is 50° C., and pressure is 16.6 atm. 
     
     
         5 . A process according to  claim 1 , wherein the product recovered from step b) is subject to mechanical agitation operation, at a temperature of 50° C., for a maximum of 10 minutes up to the completion of the transesterification reaction.