Nanostructured sodium-zeolite imidazolate framework (ZIF-8) doped with potassium by sol-gel processing for biodiesel production from soybean oil

Zeolite imidazolate framework (ZIF-8) doped with potassium (KNa/ZIF-8) was prepared under hydrothermal conditions. FTIR, powder XRD, scanning electron microscopy, N-2 physisorption and TGA were used to characterize synthesized catalysts. Furthermore, biodiesel was synthesized using soybean oil as the feedstock by KNa/ZIF-8-catalyzed transesterification process. In order to increase the basicity and consequently improve the performance of ZIF-8 in the transesterification of soybean oil with methanol, sodium and potassium were added to it. The effect of various reaction parameters, including methanol/oil molar ratio, reaction, catalyst mass and temperature on the reaction, was studied. Using KNa/ZIF-8 and methanol/oil molar ratio of 10:1 over a period of 3.5 h afforded a remarkable conversion of > 98. The solid catalyst can be recycled least three times under mild conditions. KNa/ZIF-8 demonstrated higher activity in the transesterification of soybean oil compared with Na and K (as dopant) modifications on the conventional support (SiO2) and other MOF (MIL-101 and MIL-100) materials. [GRAPHICS] .