Continuous production of biodiesel fuel by enzymatic method

Abstract

A method for continuously producing a fatty acid ester of the present invention comprises (a) mixing and agitating an oil and fat starting material and a lower alcohol, and supplying a mixture to one of the catalyst reaction tubes filled with a lipase; (b) producing a fatty acid ester and glycerin in the catalyst reaction tube; (c) introducing an outflowing liquid from the catalyst reaction tube into a glycerin separation tank, thereby collecting the glycerin; (d) adding a lower alcohol to a separated liquid obtained by separating the glycerin from the outflowing liquid, mixing and agitating an obtained material, and supplying a mixture to a following catalyst reaction tube; (e) repeating the steps (b) to (d) until supply to a last catalyst reaction tube is performed; and (f) collecting a fatty acid ester from the separated liquid obtained from the last catalyst reaction tube. According to the method of the present invention, the concentration of a lower alcohol can be strictly controlled and by product glycerin can be automatically removed.

1 . A method for continuously producing a fatty acid ester in a reaction apparatus having a plurality of stages of catalyst reaction tubes filled with a lipase, comprising:
 (a) mixing and agitating an oil and fat starting material and a lower alcohol, and supplying a mixture to one of the catalyst reaction tubes;   (b) producing a fatty acid ester and glycerin in the catalyst reaction tube to which the oil and fat starting material and the lower alcohol are supplied;   (c) introducing an outflowing liquid from the catalyst reaction tube into a glycerin separation tank, thereby collecting the glycerin;   (d) adding a lower alcohol to a separated liquid obtained by separating the glycerin from the outflowing liquid, mixing and agitating an obtained material, and supplying a mixture to a following catalyst reaction tube;   (e) repeating the steps (b) to (d) until supply to a last catalyst reaction tube is performed;   (f) introducing an outflowing liquid from the last catalyst reaction tube into a glycerin separation tank placed downstream of the last catalyst reaction tube, thereby collecting glycerin, and obtaining a separated liquid obtained by separating the glycerin from the outflowing liquid; and   (g) collecting a fatty acid ester from the separated liquid obtained in the step (f).   
     
     
         2 . A method according to  claim 1 , wherein a liquid flow rate in the reaction apparatus is at least 2.15 cm/min. 
     
     
         3 . A method according to  claim 1 , wherein an amount of the lower alcohol supplied to each of the catalyst reaction tubes is 0.5 to 1.0 mol equivalent with respect to the oil and fat starting material. 
     
     
         4 . A method according to  claim 1 , wherein the number of stages of the catalyst reaction tubes is 2 to 10. 
     
     
         5 . A method according to  claim 1 , wherein the oil and fat starting material is a vegetable oil and fat, an animal oil and fat, a fish oil, an oil and fat produced by a microorganism, a mixture thereof, or a waste oil thereof. 
     
     
         6 . A method according to  claim 1 , wherein the lower alcohol is methanol, ethanol, n-propanol, or n-butanol. 
     
     
         7 . A method according to  claim 1 , further comprising following the step (f): (f′) repeating the steps (a) to (f) using the separated liquid obtained in the step (f) as the oil and fat starting material. 
     
     
         8 . An apparatus for continuously producing a fatty acid ester, comprising:
 a plurality of stages of catalyst reaction tubes that are filled with a lipase;   a glycerin separation tank that is placed downstream of each of the catalyst reaction tubes, and that separates an outflowing liquid from the catalyst reaction tube into glycerin and a separated liquid;   a lower alcohol supply port that is placed upstream of each of the catalyst reaction tubes; and   a mixing means that is placed between each of the lower alcohol supply ports and each of the catalyst reaction tubes for mixing an oil and fat starting material or the separated liquid and a lower alcohol;   wherein, in each stage of the catalyst reaction tubes, a mixture of the oil and fat starting material or the separated liquid from the glycerin separation tank and the lower alcohol is supplied from an upper portion of the catalyst reaction tube, and an outflowing liquid from a lower portion of the catalyst reaction tube is introduced into the glycerin separation tank.   
     
     
         9 . An apparatus according to  claim 8 , wherein a liquid flow rate in the apparatus is adjusted to at least 2.15 cm/min. 
     
     
         10 . An apparatus according to  claim 8 , wherein an amount of the lower alcohol supplied to each of the catalyst reaction tubes is adjusted to 0.5 to 1.0 mol equivalent with respect to the oil and fat starting material. 
     
     
         11 . An apparatus according to  claim 8 , wherein the number of stages of the catalyst reaction tubes is 2 to 10.