Abstract
In the present study, new hetrogeneous catalysts, in which phosphotungstic acid is chemically bonded to hydrophobic highly crosslinked poly(4-divinylbenzene-co-vinylbenzyl chloride) via a soft linker, ethylenediamine (Cat-2C) or 1,8-diaminooctane (Cat-8C). The synthesized polymer was identified by infrared, Raman spectroscopy, scanning and transmittance electron microscopy, and dispersibility test. The prepared catalysts possessed uniform core-shell structure and high acidic sites. The presence of vinyl benzyl chloride in the polymer enables more phosphotungstic acid on the surface of the polymer with excellent dispersibility. Utilizing the polymer structure, synergies between acidic and hydrophilic sites (onium ion) sites lead to good results than methyl and ethyl oleate (99.8%, 84.3%) using a low ratio of alcohol and oleic acid and a short time compared to other catalysts. The catalysts showed superior catalytic performance originated from favoring the smooth transportation of reactant and product. The durability of catalysts was unaltered up to 7 cycles with no loss of phosphotungstic acid. Cat-8C was tested in the transesterification of castor oil process. Transesterification of castor oil was conducted at the determined optimal condition, and the characterization of the produced biodiesel is reported.
[Display omitted]
•Successful design of PTA-functionalized cross-linked polymers.•PTA is chemically bonded to porous polymers through a soft linker.•Methyl, and ethyl oleate (99.8%, 84.3%) yielded at low molar ratio & short time.•The durability of catalysts was almost retained up to 7th cycles.•Transesterification of castor oil for biodiesel production was reported.