Issue Date: March 14, 2016
Nickel catalyst converts tough plant lignin into valuable chemicals
To make fuels and chemicals from biomass, producers typically use the sugar-containing cellulose components. But first they must remove the surrounding lignin, a hardy phenolic biopolymer that helps support plant structure. Researchers have been looking for viable methods to crack apart the lignin into useful chemical intermediates, with some success coming from using precious-metal catalysts. A new study shows that an inexpensive nickel catalyst can transform 68% of lignin from the grass Miscanthus into aromatic compounds, while preserving residual plant sugars for subsequent conversion to fuels and other chemicals (ACS Sustainable Chem. Eng. 2016, DOI: 10.1021/acssuschemeng.5b01776). Mahdi M. Abu-Omar of Purdue University and colleagues combine 1 g of milled Miscanthus with 45 mL of methanol in a reactor containing nickel dispersed on activated carbon. The researchers place the catalyst in a microporous stainless steel cage so that the nickel can contact phenolic oligomers that form as the lignin breaks apart under high pressure and temperature, while keeping the catalyst separate from the carbohydrate residue left behind by the reaction. The catalyst deoxygenates the oligomers, turning them into a range of compounds, including dihydroeugenol, propylsyringol, and ferulic acid methyl ester, which can be used to make vanillin, the principal component of vanilla flavoring. The team further treats the residue with an iron chloride catalyst to make furfural and levulinic acid—products that can be used to make biofuels or other chemicals.
- Chemical & Engineering News
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