Sulfonated porous organic polymer as a highly efficient catalyst for the synthesis of biodiesel at room temperature

• Synthesis of a sulfonic acid grafted porous organic polymer PDVTA-SO3H, by post synthetic functionalization method.
• The polymer possess high surface area (SBET = 406 m2 g−1) and high surface acidity 2.3 mmol g−1.
• PDVTA-SO3H showed high catalytic activity for the synthesis of biodiesel compounds from long chain fatty acids.

A new functionalized porous organic polymer bearing sulfonic acid groups (PDVTA-SO3H) at the pore surface with high surface area (SBET = 406 m2 g−1) and Brønsted acidity is reported. The material has been synthesized via post-synthetic sulfonation of the porous co-polymer poly-divinylbenzene-co-triallylamine (PDVTA-1) using chlorosulfonic acid as sulfonating agent. A detailed characterization of the SO3H functionalized porous polymeric material has been carried out using N2 sorption, FT-IR and UV–vis spectroscopy, HR-TEM, FE-SEM, thermogravimetric and elemental analyses. Temperature programmed desorption of NH3 (TPD-NH3 analysis) of PDVTA-SO3H revealed a very high surface acidity of 2.3 mmol  g−1. Such high acidity of PDVTA-SO3H has been explored to investigate its catalytic efficiency towards eco-friendly production of biodiesel via esterification of long-chain free fatty acids (FFA) to the respective fatty acid monoalkyl esters (FAMEs) at room temperature using methanol as reactant as well as solvent. The sulfonated porous polymer is found to be a very active and reusable solid acid catalyst giving high yields (∼92–98%) of various biodiesel compounds under very mild reaction conditions.

Figure optionsDownload high-quality image (177 K)Download as PowerPoint slideA new porous organic polymer functionalized with sulfonic acid groups and high Brønsted acidity is reported. The material showed excellent catalytic activity for the biodiesel synthesis at room temperature.