Abstract: Disclosed is a catalyst based on synthetic silica, in a heterogeneous catalysis method, to promote the effective conversion of residual glycerin, resulting from the production of biodiesel, into formic acid with high selectivity and stability, in a continuous flow reaction. The conversion of residual glycerin occurs by homogeneous catalysis, by the action of components remaining from the synthesis of biodiesel, with the formation of major compounds, such as formic acid, cyclic ethers and diglycerol, in continuous flow and reflow reactions. The reaction can also be carried out by adding sodium salts in the homogeneous catalytic conversion process of commercial glycerin. The process values the residual glycerin, without the need for purification before its transformation into products with high added value, but of renewable origin, adding more interest and potential.