Microreactor Process for Making Biodiesel

Abstract

Embodiments of a method for using a microreactor to produce biodiesel. For example, the method may comprise flowing a first fluid comprising an alcohol and a second fluid comprising an oil to the microreactor. Alcohols typically, but not necessarily, are lower aliphatic alcohols, including methanol, ethanol, amyl alcohol or combinations thereof. Biodiesel production can be under supercritical conditions, where such conditions typically are determined relative to the alcohol component. Suitable sources of oil products include soy, inedible tallow and grease, corn, edible tallow and lard, cotton, rapeseed, sunflower, canola, peanut, safflower, and combinations thereof. Catalysts can be used to facilitate biodiesel production, such as metal oxides, metal hydroxides, metal carbonates, alcoholic metal carbonates, alkoxides, mineral acids and enzymes. Oil conversion to biodiesel typically increases with increasing mean microreactor residence time. Certain embodiments of the present invention can include blending biodiesel produced by the method with petroleum-based products.

1 . A method for producing biodiesel, comprising:
 providing a microreactor;   flowing a first fluid comprising an alcohol and a second fluid comprising an oil to the microreactor; and   using the microreactor to produce biodiesel.   
   
   
       2 - 5 . (canceled) 
   
   
       6 . The method according to  claim 1  where the alcohol is methanol, ethanol, propanol, butanol, amyl alcohol or combinations thereof. 
   
   
       7 . (canceled) 
   
   
       8 . The method according to  claim 1  where the oil is derived from soy, inedible tallow and grease, corn, edible tallow and lard, cotton, rapeseed, sunflower, canola, peanut, safflower, and combinations thereof. 
   
   
       9 . The method according to  claim 1  further comprising using a catalyst to produce the biodiesel, where the catalyst is a metal oxide, metal hydroxide, metal carbonate, alcoholic metal oxide, alcoholic metal hydroxide, alcoholic metal carbonate, an alkoxide, a mineral acid, an enzyme, or combinations thereof. 
   
   
       10 - 11 . (canceled) 
   
   
       12 . The method according to  claim 9  where the catalyst is sodium hydroxide, potassium hydroxide, sodium alkoxide, potassium alkoxide, or combinations thereof. 
   
   
       13 - 14 . (canceled) 
   
   
       15 . The method according to  claim 1  further comprising blending biodiesel produced by the method in an amount greater than zero weight percent petroleum product to less than 100 weight percent with petroleum-based products. 
   
   
       16 . (canceled) 
   
   
       17 . The method according to  claim 1  comprising a transesterification process. 
   
   
       18 . The method according to  claim 1  performed at supercritical conditions. 
   
   
       19 . The method according to  claim 18  where the alcohol is supercritical. 
   
   
       20 . The method according to  claim 1  where the oil is a triglyceride having a formula 
     
       
         
         
             
             
         
       
     
     where R 1 , R 2  and R 3  independently are fatty acids. 
   
   
       21 . The method according to  claim 20  where the fatty acids have carbon chain lengths ranging from at least as few as 10 carbon atoms to at least as many as 20 carbon atoms. 
   
   
       22 . (canceled) 
   
   
       23 . The method according to  claim 20  where the fatty acids are selected from lauric acid, palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid. 
   
   
       24 . The method according to  claim 20  where the fatty acid includes at least one site of unsaturation other than a carbon-carbon double bond. 
   
   
       25 . The method according to  claim 1  further comprising providing at least a 3:1 molar ratio of alcohol-to-triglycerides. 
   
   
       26 . The method according to  claim 1  where a temperature at which a transesterification reaction is conducted is within a range of from about 25° C. to less than about 350° C. 
   
   
       27 . (canceled) 
   
   
       28 . The method according to  claim 1  further comprising providing plural microreactors. 
   
   
       29 . The method according to  claim 1  where oil and alcohol fluid layers have fluid layer thicknesses in the microreactor of from about 10 μm to about 500 μm. 
   
   
       30 . The method according to  claim 1  where surface-to-volume ratio of microreactor microchannels is from about 10,000 m 2 /m 3  to about 50,000 m 2 /m 3 . 
   
   
       31 . (canceled) 
   
   
       32 . The method according to  claim 1  where the microreactor includes at least one manifold for distributing fluid flow to individual microchannels. 
   
   
       33 . (canceled) 
   
   
       34 . The method according to  claim 1  where the oil is soybean oil, the alcohol is methanol or ethanol, and the method further comprises using a metal hydroxide catalyst. 
   
   
       35 . The method according to  claim 34  where metal hydroxide catalyst is used in an amount of about 1.0 weight % of the soybean oil used for transesterification. 
   
   
       36 . The method according to  claim 1  where oil and alcohol fluids are pumped to the microreactor using a pump volume flow rate ratio of oil:alcohol of about 3.4. 
   
   
       37 . The method according to  claim 1  where oil and alcohol fluids are used at a molar ratio of oil-to-alcohol of about 1:7.2. 
   
   
       38 . The method according to  claim 1  further comprising separating two phases produced by the reaction using a distillation process, a centrifugation process, or combinations thereof. 
   
   
       39 - 40 . (canceled) 
   
   
       41 . The method according to  claim 1  comprising using a microreactor microchannel having a 100 μm thickness, soybean oil, and a transesterification processing temperature at or about ambient, and where conversion of soybean oil to biodiesel ranges from about 12% at about 0.4 MRT to about 91% at 10 minutes MRT. 
   
   
       42 . The method according to  claim 1  comprising using a microreactor microchannel having a 100 μm thickness, soybean oil, and a transesterification processing temperature at or about ambient, and where total methyl ester concentration ranges from about 0.3 mol/l at about 0.4 minute MRT to about 2.5 moles/l at about 10 minutes MRT. 
   
   
       43 . The method according to  claim 1  comprising using a microreactor microchannel having a 200 μm thickness, soybean oil, and a transesterification processing temperature at or about ambient. 
   
   
       44 . The method according to  claim 43  where conversion of soybean oil to biodiesel ranges from about 4% at about an 0.4 MRT to about 86% at about 10 minutes MRT. 
   
   
       45 - 64 . (canceled) 
   
   
       65 . A method for producing biodiesel comprising:
 providing a microreactor;   flowing a first fluid to the microreactor comprising a lower aliphatic alcohol;   flowing a second fluid comprising an oil to the microreactor, the oil comprising a triglyceride having a formula   
     
       
         
         
             
             
         
       
     
     where R 1 , R2 and R 3  independently are fatty acids having hydrocarbon chain lengths ranging from at least as few as 10 carbon atoms to at least as many as 20 carbon atoms;
 providing a reaction catalyst selected from the group consisting of metal oxides, metal hydroxides, metal carbonates, alcoholic metal oxides, alcoholic metal hydroxides, alcoholic metal carbonates, alkoxides, mineral acids, enzymes, or combinations thereof; 
 using the microreactor to produce biodiesel; and 
 blending biodiesel produced by the method with petroleum-based products in an amount greater than zero weight percent petroleum product to less than 100 weight percent petroleum product. 
 
   
   
       66 . The method according to  claim 65  performed at supercritical conditions. 
   
   
       67 . The method according to  claim 65  where the alcohol is supercritical. 
   
   
       68 . The method according to  claim 65  further comprising providing plural microreactors. 
   
   
       69 . The method according to  claim 65  further comprising using a cosolvent. 
   
   
       70 . The method according to  claim 69  where the cosolvent is carbon dioxide.