Heteropolyacid Nanoreactor with Double Acid Sites as a Highly Efficient and Reusable Catalyst for the Transesterification of Waste Cooking Oil

A solid zirconjumdodecatungstophosphate ZR(0.7)H(0.2)PW(12)O(40) (abbrevinted as ZrHPW) with nanotube structure has been synthesized using natural cellulose fiber as a template. The structure and morphology were characterised to show that the primary Keggin structure remained intact in a nanotube with large surface area (256 m(3)/g). On the basis of hte research of acidity. ZrHPW exhibited higher acid strength, both Bronsted acidity and Lewis acidity in one to show higher efficiency, and reusable catalytic activity in biodiesel production from low-quality feedstocks. A synergistic effect results from the channels in the nanotube and doubly catalytic sites to provide an efficient approach to acidic sites for reactants, as well enough space for subsequent recycling.