System and methods for making bioproducts

A process for making a fatty acid alkyl ester from a mixture comprising a fatty acid glyceride;

• a fatty acid and at least one component selected from the group consisting of a gum, a suspended solid, a dissolved metal, and combinations thereof, comprising:
• a) purifying the mixture by:
• i) contacting the mixture with water;
• ii) separating the mixture to reduce the amount of at least one component from the mixture while the amount of fatty acid relative to the amount of fatty acid glyceride in the mixture is substantially the same;
• and
• iii) drying the mixture;
• and
• b) contacting the purified mixture from step a) with an alcohol and a supported heterogeneous acid catalyst in a first fixed bed reactor and performing esterification of fatty acids and transesterification of fatty acid glycerides to produce a first reaction mixture comprising a fatty acid alkyl ester, wherein said heterogeneous acid catalyst comprises one or more metals selected from the group consisting of molybdenum (Mo), iron (Fe), cobalt (Co) and chromium (Cr);
• c) transferring at least a portion of the first reaction mixture to a second fixed bed reactor,
• d) contacting the transferred portion of the first reaction mixture with additional alcohol and said heterogeneous acid catalyst and performing esterification of fatty acids and transesterification of fatty acid glycerides to produce a second reaction mixture comprising a fatty acid alkyl ester, unreacted alcohol, and glycerin;
• wherein the acid number of the second reaction mixture is less than about 0.5, 0.4, 0.3, 0.2, or 0.1.