The hydrogenation of sugars into polyols is often carried out on noble metals such as ruthenium Ru or on Raney nickel, with little work reported on supported non-noble metals. However, the cost of noble metals is high, their abundance is low, and both their cost and availability are prone to large fluctuations. Substitutes to noble metals should be found in the first period of transition metals, which encompasses especially abundant and cheap metals, but that may deactivate upon reaction or, like nickel, induce hydrogenolysis side-reactions.

In this context, the potential of iron-based bimetallic combinations deserves to be fully explored.

However, the hydrogenation/hydrogenolysis balance of the catalyst is not simply governed by the ratio between the two metals, but also by their degree of interplay, i.e., alloyed vs. segregated metals, a crucial point to take into account for a metal sensitive to oxidation like Fe. The possibility to synthesize precisely controlled Fe-based bimetallic nanoparticles appears to be limited when the catalyst is prepared by standard methods, with particles of different size, structure or composition coexisting in the catalyst.

As a consequence, no firm conclusion can currently link the catalyst formulation and the catalytic properties of Fe-based systems owing to a lack of control of the nature of the nanoparticles at the nanometer level, leading to difficulties to interpret, reproduce, extrapolate and rationalize catalytic results.