IR Study of Fe and Ni Nanoscale Particles in the Carbon Dioxide Reforming of Lignin

Structural changes in lignin whose surface is modified with nanoscale nickel and iron-containing particles are studied via vibrational spectroscopy during the reforming of carbon dioxide, stimulated with microwave radiation. It is shown that vanillic acid is transformed into synthesis gas upon convective heating if there are conditions for its existence in monomeric form. The applied metal-containing components greatly alter the structural characteristics of lignin. An internal standard shows that nickel deposited on the surface of lignin from an acetate salt aqueous solution reacts with surface aldehyde groups to oxidize them into carboxylate ones. IR data obtained in situ inside a catalytic cell show that the decomposition of lignin in the presence of nanoscale nickel-containing particles in a CO2 environment during convective heating yields vanillin derivatives (acid and alcohol) that are firmly anchored on the surface of the material by hydrogen bonds. Nanoscale iron particles deposited on a surface of acetylacetonate complex are strongly coordinated on alkoxy groups of lignin. The organic matter of lignin decomposes during convective heating in CO2 to form light products (hydrocarbons and oxygenates).