Preparation of ethane-bridged organosilica group and keggin type heteropoly acid co-functionalized ZrO2 hybrid catalyst for biodiesel synthesis from eruca sativa gars oil

Abstract

A series of mesostructured ZrO2-based hybrid catalysts, functionalized by both an ethane-bridged organosilica group and the Keggin type heteropoly acid, H3PW12O40–ZrO2–Si(Et)Si, were prepared by one-step sol-gel-hydrothermal method in the presence of a triblock copolymer surfactant (F127). The materials were well characterized by spectroscopy methods such as FT-IR and MAS NMR, transmission electron microscopy, and nitrogen gas physisorption measurements to confirm the structural integrity of the Keggin units and ethane-bridged organosilica groups in the hybrid materials, and to test the mesostructure, morphology, and porosity of the materials. The materials were subsequently utilized as environmentally-friendly solid acid catalysts in the transesterification of low-cost Eruca Sativa Gars oil with methanol to produce fatty acid methyl esters under atmosphere refluxing. Compared with alkyl-free H3PW12O40–ZrO2, the prepared H3PW12O40–ZrO2–Si(Et)Si exhibited higher catalytic activity toward the target reaction. This enhanced acid-catalytic activity after the introduction of both acidic and hydrophobic functionalities within the ZrO2 matrix was explained in terms of strong Brϕnsted acidity, excellent porosity, and enhanced hydrophobicity of the hybrid materials.