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Novel Synthesis of Immobilized Brønsted‐ Acidic Ionic Liquid: Application in Lignin Depolymerization
Author(s) -
Singh Sandip K.,
Dhepe Paresh L.
Publication year - 2018
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201703050
Subject(s) - depolymerization , lignin , chemistry , catalysis , ionic liquid , thermogravimetric analysis , gel permeation chromatography , covalent bond , sulfonic acid , organic chemistry , polymer
Designing of efficient catalyst for the valorization of lignin is a topic of long neglect due to intrinsic properties of lignin. We show designing of an efficient, stable and recyclable Immobilized‐Brønsted acidic ionic liquid (I‐BAIL), which was further used as a solid acid catalyst for the depolymerization of lignin. The synthesized I‐BAIL catalyst with sulfonic acid (–SO 3 H) groups was found to be stable until 250 °C and has 42.2 wt .% loading of BAIL anchored on silica framework. The detailed characterization (elemental, Thermogravimetric analysis, Fourier transformation‐Infrared, Nuclear magnetic resonance) of catalyst disclosed formation of strong covalent bond between Si and carbon of BAIL, which in turn is responsible for achieving a stable catalyst. The catalyst could successfully depolymerize range of lignin substrates with high molecular weight (60000 Dalton) at 200 °C in 1 h to achieve 90% yield of tetrahydrofuran soluble products with good mass balance. The formation of products and correlation of products with lignin was achieved with the help of Nuclear magnetic resonance, gel permeation chromatography, gas chromatography, gas chromatography‐mass spectrometry, high performance liquid chromatography etc.