Reusable ruthenium-based catalyst could be a game-changer for the biomass industry

Now, researchers at Tokyo Institute of Technology (Tokyo Tech) have developed a highly selective catalyst consisting of ruthenium nanoparticles supported on niobium pentoxide (Ru/Nb₂O₅).

In a study published in the Journal of the American Chemical Society, the team demonstrated that Ru/Nb₂O₅ is capable of producing primary amines from carbonyl compounds with ammonia (NH3) and dihydrogen (H2), with negligible formation of by-products.

The study compared the extent to which different catalysts could convert furfural to furfurylamine in a process known as reductive amination1. This reaction is one of the most useful methods for producing primary amines on an industrial scale. The Ru/Nb₂O₅ catalyst outperformed all other types tested — remarkably, a yield of 99% was attained when ammonia was used in excess quantity.

Even after three recycles, the Ru/Nb₂O₅ catalyst achieved consistent results, with consecutive yields of over 90%. The superior catalytic efficiency is thought to be due to ruthenium's weak electron-donating properties on the Nb₂O₅ surface (see Figure 1).

Michikazu Hara of Tokyo Tech's Laboratory for Materials and Structures and his co-workers then explored how effectively the new catalyst could break down biomass (in the form of glucose) into 2,5-bis(aminomethyl)furan, a monomer for aramid production.

Previous experiments using a nickel-based catalyst led to a yield of around 50% from glucose-derived feedstock (5-hydroxymethylfurfural).

The new catalyst used in combination with a so-called ruthenium-xantphos complex produced a yield of 93%. With little to no by-products observed, Ru/Nb₂O₅ represents a major breakthrough in the clean, large-scale production of biomass-derived materials.

Further studies to expand on these initial findings are already underway. By pushing the boundaries of material design, the researchers say that Ru/Nb₂O₅ may accelerate the production of environmentally friendly plastics, rubber and heat-resistant aramid fibers2.

In future, the Ru/Nb₂O₅ catalyst may also impact the development of novel anti-cancer drugs, anti-bacterials, pesticides, agrochemicals, fertilizers, bio-oils and biofuels.