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Renewable Aromatics from Kraft Lignin with Molybdenum‐Based Catalysts
Author(s) -
Cattelan Lisa,
Yuen Alexander K. L.,
Lui Matthew Y.,
Masters Anthony F.,
Selva Maurizio,
Perosa Alvise,
Maschmeyer Thomas
Publication year - 2017
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201700374
Subject(s) - depolymerization , catalysis , lignin , molybdenum , chemistry , supercritical fluid , ionic liquid , yield (engineering) , organic chemistry , inorganic chemistry , nuclear chemistry , materials science , metallurgy
The catalytic depolymerization of Kraft lignin in supercritical ethanol was explored in the presence of Mo 2 C‐ and MoS 2 ‐based catalysts. At 280 °C, Mo 2 C and Mo 2 C/Al 2 O 3 afforded aromatic yields of 425 and 419 mg g −1 lignin, respectively: amongst the highest yields reported to date. Ionic–liquid–assisted delamination of MoS 2 resulted in highly active catalysts, capable of quantitative conversion of lignin at the expense of aromatic yield (approximately 186 mg g −1 lignin). Across all the catalysts studied, between 0.04 wt % and 0.38 wt % of molybdenum leached into the solution under supercritical conditions, according to inductively coupled plasma (ICP) analyses (corresponding to 27–570 μg of molybdenum in the reaction supernatant). A small contribution to the molybdenum in solution comes from the reactor itself (Hastelloy C contains 16 wt % Mo). Analysis of a depolymerization performed with fresh Kraft lignin and the soluble portion of the reaction mixture from a previous reactor run indicated that the leached species were neither active enough to afford the high conversions observed, nor selective enough to give high yields of aromatic products. In conjunction with the ICP data and differential chemoselectivities of the Mo 2 C‐ and MoS 2 ‐based catalysts, these results suggest that the bulk of the catalysis is heterogeneous.