Green Chemistry Blog

Hydrolytic hydrogenation of cellulose with hydrotreated caesium salts of heteropoly acids and Ru/C.  Hydrolysis of cellulose by an acid catalyst, followed by metal-catalysed hydrogenation gives hexitols, which can be used as renewable chemicals and fuels.  In this study the authors use a combined catalyst of caesium salts of heteropoly acids (HPAs) and Ru/C.  Although HPAs have been used before, they cannot be recovered from the reaction afterwards, which greatly limits their use in industrial processes.

However, in this work Sels and co-workers have found that the caesium salts of HPAs are not only highly selective (giving up to 90% yields of hexitols) and can be performed under mild reaction conditions, the Cs HPA salts could be recovered by simple recrystallisation at room temperature without using organic solvents. (Green Chem., 2011, DOI: 10.1039/c1gc15350a)

Selective oxidation of 5-hydroxymethyl-2-furfural using supported gold-copper nanoparticles. 5-Hydroxymethyl-2-furfural (HMF), formed from the dehydration of sugars, can be oxidised to 2,5-furandicarboxylic acid (FDCA), which recently has been suggested as a substitute for terephthalate acid – the monomer for the production of terephthalate plastic. However, currently many strategies to oxidise HMF to FDCA have various drawbacks, including the use of stoichiometric oxidants. 

In this work Hutchings and colleagues report the use of gold-copper supported nanoparticles as an effective catalyst for the oxidation of HMF to FDCA.  Although supported gold nanoparticles have been applied to this reaction previously, catalyst stability has remained very low. However, the bimetallic nanoparticles reported here, supported on titania, exhibit a remarkable degree of stability, even in the presence of base.  The catalyst could be recovered by filtration and reused several times without significant loss of activity. (Green Chem., 2011, DOI: c1gc15355b)