@article { ISI:000347513400044,
	title = {Lignin depolymerization into aromatic monomers over solid acid catalysts},
	journal = {ACS Catalysis},
	volume = {5},
	number = {1},
	year = {2015},
	month = {JAN},
	pages = {365-379},
	publisher = {AMER CHEMICAL SOC},
	address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA},
	abstract = {<p>It is imperative to develop an efficient and environmentally benign pathway to valorize profusely available lignin, a component of nonedible lignocellulosic materials, into value-added aromatic monomers, which can be used as fuel additives and platform chemicals. To convert lignin, earlier studies used mineral bases (NaOH, CsOH) or supported metal catalysts (Pt, Ru, Pd, Ni on C, SiO2, Al2O3, etc.) under a hydrogen atmosphere, but these methods face several drawbacks such as corrosion, difficulty in catalyst recovery, sintering of metals, loss of activity, etc. Here we show that under an inert atmosphere various solid acid catalysts can efficiently convert six different types of lignins into value-added aromatic monomers. In particular, the SiO2Al2O3 catalyst gave exceptionally high yields of ca. 60\% for organic solvent soluble extracted products with 95 +/- 10\% mass balance in the depolymerization of dealkaline lignin, bagasse lignin, and ORG and EORG lignins at 250 degrees C within 30 min. GC, GC-MS, HPLC, LC-MS, and GPC analysis of organic solvent soluble extracted products confirmed the formation of aromatic monomers with ca. 90\% selectivity. In the products, confirmation of retention of aromatic nature as present in lignin and the appearance of several functional groups has been carried out by FT-IR and H-1 and C-13 NMR studies. Further, isolation of major products by column chromatography was carried out to obtain aromatic monomers in pure form and their characterization by NMR is presented. A detailed characterization of six different types of lignins obtained from various sources helped in substantiating the catalytic results obtained in these reactions. A meticulous study on fresh and spent catalysts revealed that the amorphous catalysts are preferred to obtain reproducible catalytic results.</p>},
	keywords = {aromatic monomers, Biomass, column chromatography, depolymerization, lignin, solid acid catalysts},
	issn = {2155-5435},
	doi = {10.1021/cs501371q},
	author = {Deepa, Ayillath K. and Dhepe, Paresh Laxmikant}
}
@article {46424,
	title = {Formic-acid-induced using recyclable-ionic liquids as catalysts for lignin conversion into aromatic co-products},
	journal = {Waste and Biomass Valorization},
	year = {2019},
	month = {NOV},
	type = {Article; Early Access},
	abstract = {<p>Lignin has been widely named as a sustainable and renewable bioresource of energy, fuels, chemicals and materials, particularly phenolic chemicals production on Earth. These bio-derived compounds are in great potential need of biorefinery to valorize complete plant biomass. Lignin depolymerization showed a great promise approach to convert into low molecular aromatic products. In this report, high molecular weight (54,000 Da) lignin depolymerization into maximum yields (87\%), (\&gt;= 95 +/- 6\% mass balance) using a formic acid along with dual (-SO3H) functionalized imidazole-based recyclable (4 times) Bronsted acidic ionic liquids (BAILs) as catalysts have been investigated in H2O-CH3OH (1:5, v/v) at 120 degrees C for 1 h. The structural correlations between the lignin and aromatic products were studied by bulk (CHNS, GPC, etc.) and molecular (UV-Vis, FT-IR, NMR (1D/2D) levels experimental techniques. Additionally, the identification of aromatic products was carried out by applying HPLC, GC and GC-MS techniques. Graphic Addition of a formic acid into Bronsted acidic ionic liquids improved the catalytic efficiency significantly for lignin depolymerization into 87\% low molecular weight aromatic products. [GRAPHICS] .</p>
},
	keywords = {Bulk and molecular levels analysis, depolymerization, Dual functionalized ionic liquids, Formic acid, lignin},
	issn = {1877-2641},
	doi = {10.1007/s12649-019-00896-3},
	author = {Singh, Sandip K. and Dhepe, Paresh L.}
}
