Sinter-Resistant Nickel Catalyst for Lignin Hydrogenolysis Achieved by Liquid Phase Atomic Layer Deposition of Alumina

摘要

Lignin hydrogenolysis is a key step in the sustainable production ofrenewable bio-based chemicals and fuels. Heterogeneous metal catalystshave led to high yields but they rapidly deactivate, notably due to nanoparticlesintering and carbonaceous deposit formation. While these deposits can beremoved by regeneration, sintering is irreversible and a significant barrier tocommercialization. Here, simple liquid phase atomic layer deposition is usedto deposit an alumina layer to protect nickel particles from sintering. In thegas phase, it is proved that alumina can prevent sintering during reductionup to 600℃. This catalyst for hydrogenolysis of extracted lignin in batch andcontinuous operation is used. In batch, the overcoated catalyst maintainshigh monomer yields with little sintering over four cycles of reuse whilethe yield obtained with the catalyst without an overcoat reduces to half andsevere sintering occurs. In a continuous flow reactor, deactivation rates arethree times lower for the catalyst with the alumina overcoat. Microscopyimages confirm that the alumina overcoat largely preserves nickel particlesizes after ten days of operation. The results demonstrate that catalyst overcoatingwith metal oxides substantially slows irreversible deactivation duringlignin hydrogenolysis, which could facilitate the development of continuouslignin upgrading.