Applied Catalysis B: Environmental, Vol.182, 15-25, 2016
A new approach to polymer-supported phosphotungstic acid: Application for glycerol acetylation using robust sustainable acidic heterogeneous-homogenous catalyst
Biodiesels produced from renewable sources is now recognized as a green fuel and exhibit superior fuel properties, and they are more environmentally friendly than petroleum-based fuels. In this paper, the functionalization was performed through quaternization of one amine belonged ethylenediamine with chloromethyl group of solid polymer, and the remaining amine could act as active sites to immobilize H3PW12O40 (PTA) through ionic bonding interaction. Thanks to the strong acidity of PTA and swelling behavior of ethylenediamine on the surface and micro-mesochannels of poly(divinylbenzene-co-vinylbenzyl chloride) copolymer (PDVC), the catalysts showed properties of heterogeneous and homogeneous behavior and presents new opportunities for tailored new solid acids in sustainable chemistry. The catalysts were characterized by various structural morphology (XRD, N-2-sorption, HRTEM and FESEM) and compositional (FTIR, Raman spectra and XPS) techniques. This catalyst showed much higher activity than other solid acidic catalysts due to the enriched PTA-surface acid sites (6.78 mmol g(-1)) and the minimized diffusion limitation as well as high level of catalyst dispersion in reaction mixture due to the unique structure. Furthermore, by enclosing the PTA acidic material to a tailored free amino group in PDVC, an even more enduring catalyst was developed and applied to glycerol acetylation reaction. This catalyst displayed high conversion (99.9%), selectivity toward triacetin (73%) and superior performance in terms of endurance and leaching control of active sites compared with other catalysts. The catalyst was capable of withstanding for seven times durable run of continuous process at 100 degrees C without deactivation. During the reaction time, the leaching of PTA species was not observed and the material maintained its structural integrity. (C) 2015 Elsevier B.V. All rights reserved.