Process for the production of fatty acid methyl esters from variable feedstock using heterogeneous catalysts

A process for producing fatty acid methyl esters, comprising:

• mixing an alcohol with a feedstock oil to prepare an alcohol/oil mixture;
• reacting the alcohol/oil mixture in an acid esterification process catalyzed by a first heterogeneous catalyst, thereby producing a glycerin-containing product free of homogenous catalyst;
• separating glycerin from the glycerin-containing product by a coalescer, thereby producing a biodiesel-containing feedstock and glycerin;
• separating biodiesel from the biodiesel-containing feedstock by a coalescer, thereby producing unreacted feedstock and biodiesel;
• reacting the unreacted feedstock using a second heterogeneous catalyst in a trans-esterification process catalyzed by a second heterogeneous catalyst, thereby producing a glycerin-biodiesel-methanol mixture free of homogenous catalyst;
• separating biodiesel and glycerin in separate streams from the glycerin-biodiesel-methanol mixture by a coalescer, thereby producing additional glycerin and additional biodiesel;
• and
• wherein all process steps are free of any homogeneous catalyst.