Hydrotreatment of lignin dimers over NiMoS-USY: effect of silica/alumina ratio
Journal article, 2021

Sulfides of NiMo over a series of commercial ultra-stable Y zeolites were studied in an autoclave reactor to elucidate the effect of silica/alumina ratio (SAR = 12, 30, and 80) on the cleavage of etheric C-O (beta-O-4) and C-C (both sp(3)-sp(2) and sp(2)-sp(2)) linkages present in native/technical lignin and lignin derived bio-oils. 2-Phenethyl phenyl ether (PPE), 4,4-dihydroxydiphenylmethane (DHDPM), and 2-phenylphenol, (2PP) were examined as model dimers at 345 degrees C and 50 bar of total pressure using dodecane as the solvent. The etheric C-O hydrogenolysis activity was found to be in the order NiMoY30 > NiMoY12 > NiMoY80, despite a high initial rate of C-O cleavage over NiMoY12 owing to its high acid density. A high degree of hydrodeoxygenation (HDO) and hydrocracking reactions were observed with NiMoY30 yielding >80% of deoxygenated products of which similar to 58% are benzene, toluene, and ethylbenzenes. A similar experiment with DHDPM showed the rapid cleavage of the methylene-linked C-C dimer (sp(3)-sp(2)) to phenols and cresols even with the low acid density (high SAR) catalyst, NiMoY80. Direct hydrocracking of the recalcitrant 5-5 ' linkage in 2PP is very slow, however, it cleaved via a cascade of HDO, ring-hydrogenation, and hydrocracking reactions. A high degree of hydrogenolysis and hydrocracking occurs over NiMoY30 due to suitable balance between acidity and pore accessibility, enhanced proximity between acidic and deoxygenation sites leading to a slightly higher dispersion of Ni promoted MoS2 crystallites. Overall, the product spectrum consisted of a high yield of deoxygenated products. The carbon content on the recovered catalyst was in the range of 3-7 wt%. These results pave the way for effective catalysts to break recalcitrant linkages present in lignin to obtain a hydrocarbon-rich liquid transportation fuel. An experiment with Kraft lignin over NiMoY30 shows good selectivity for deoxygenated aromatics and cycloalkanes in the liquid phase.

Author

Muhammad Abdus Salam

Chalmers, Chemistry and Chemical Engineering, Chemical Technology, Chemical Process and Reaction Engineering

You Wayne Cheah

Chalmers, Chemistry and Chemical Engineering, Chemical Technology, Chemical Process and Reaction Engineering

Hoang Phuoc Ho

Chalmers, Chemistry and Chemical Engineering, Chemical Technology, Chemical Process and Reaction Engineering

Louise Olsson

Chalmers, Chemistry and Chemical Engineering, Chemical Technology

Derek Creaser

Chalmers, Chemistry and Chemical Engineering, Chemical Technology, Chemical Process and Reaction Engineering

SUSTAINABLE ENERGY & FUELS

2398-4902 (ISSN)

Vol. 5 13 3445-3457

Combining experiments and kinetic modelling for lignin valorization to chemicals and fuels

Formas (2017-01392), 2018-01-01 -- 2020-12-31.

Subject Categories

Chemical Process Engineering

Other Chemical Engineering

Organic Chemistry

DOI

10.1039/d1se00412c

More information

Latest update

8/18/2021