(216g) Reductive Mechanocatalytic Depolymerization of Lignin
- Conference: AIChE Annual Meeting
- Year: 2018
- Proceeding: 2018 AIChE Annual Meeting
- Group: Topical Conference: Innovations of Green Process Engineering for Sustainable Energy and Environment
- Time: Monday, October 29, 2018 - 5:00pm-5:15pm
This contribution is focused on the use of reduction catalysts and hydrogen for mechanocatalytic depolymerization of lignin. The use of reduction catalysts allows for integrated depolymerization and product upgrading through hydrodeoxygenation (HDO). In the present process, an acid supported noble or transition metal catalyst and lignin are combined in a vibratory ball mill, while gaseous reagents are flown through the vessel. Reactivity studies are conducted for reductive cleavage of model dimers (e.g. benzyl phenyl ether) and HDO of model monomers (e.g. guaiacol). Acids sites on solid catalysts promote both the depolymerization and HDO reactions. In depolymerization reactions, acid sites catalyze the hydrolysis of ether bonds. For HDO, monomers can adsorb onto acid sites adjacent to metal particles. Activated hydrogen on the metal sites then reacts with the monomer, cleaving the carbon oxygen bond. The depolymerized lignin is characterized with gel permeation chromatography, nuclear magnetic resonance and infrared spectroscopy, as well as acid number and carbonyl titrations. Low molecular weight compounds are identified and quantified with gas chromatography with a mass spectrometer and a flame ionizing detector. Mechanocatalytic hydrogen-processing of lignin can overcome many hurdles for economic lignin valorization (e.g. product separations and upgrading) by simultaneously depolymerizing lignin and refining products using industrially relevant catalysts, all without solvents.