Ionic liquid grafted NH2-UiO-66 as heterogeneous solid acid catalyst for biodiesel production

In this work, acidic ionic liquid (AIL) was grafted into NH 2 -UiO-66 through acid-base interaction. And the novel heterogeneous catalyst x AIL@NH 2 -UiO-66 ( x means the mass ratio of AIL to NH 2 -UiO-66) was first applied in the field of biodiesel production. The optimal catalyst 3AIL@NH 2 -UiO-66 with good wettability (with reactants) and high acidity was prepared successfully. Accordingly, the 3AIL@NH 2 -UiO-66 can be widely applied in biodiesel production from different raw materials. The conversion of free fatty acids (FFAs) in esterification was above 90%, as well as the biodiesel yield in transesterification was above 80%, showing excellent catalytic activities of 3AIL@NH 2 -UiO-66. And the 3AIL@NH 2 -UiO-66 also revealed excellent reusability, with the conversion of oleic acid decreases from 96.86% to 90.42% after 6 runs. In addition, the interaction between any two of the three factors (catalyst dosage, reaction time and molar ratio) on the oleic acid conversion was revealed with 3D response surface technology. By the mechanism investigation, the good wettability with reactants and high acidity of the catalysts are identified as key factors for biodiesel production. The method of anchoring ionic liquids with organic linkers for the application of MOFs in biodiesel production offers abundant possibilities.