Past and Present Research Systems of Green Chemistry

Biography

Biography: Richa Km

Abstract

Lignin is generated as a major by‐product during bio-ethanol production and is a complex three dimensional amorphous biopolymer having several aromatic rings linked together via various linkages (e.g. C-C bond, C-O-C bonds, etc.). The polyphenolic structure of lignin is ideally suitable for the catalytic transformation of it into lower molecular weight substituted phenols, which can be used as octane enhancers and platform chemicals. This research focuses on the development of heterogeneous base catalyzed method for the depolymerization of lignin (Mw~60,000 Da) at milder reaction conditions (T ≤ 300°C) to obtain the intact aromatic monomers. Various solid base catalysts were evaluated for the synthesis of aromatic monomers from depolymerization of lignin. The optimization of reaction conditions such as temperature, concentrations etc. has been done to achieve the maximum yield of aromatic monomers (~51%), by suppressing the formation of degradation products (coke, char) and gas formation. Moreover, catalyst showed a constant recycle activity minimum up to 4th run with 36 % of product yields. Various physico-chemical characterizations for both fresh and spent catalyst were described to enlighten its stability. The depolymerization of lignin yields various aromatic monomers such as vanillin, guaiacol, etc. (Scheme 1) which can be further used as platform chemicals. The yield of aromatic monomers varied strongly depending on the heterogeneous base catalyst used.