Highly efficient hydrogenative ring-rearrangement of furanic aldehydes to cyclopentanone compounds catalyzed by noble metals/MIL-MOFs

Hydrogenative ring-rearrangement reaction of biomass-derived furanic aldehydes to cyclopentanone compounds catalyzed by metal/support bifunctional catalysts suffers a low selectivity of target product and serious carbon loss because of the Brønsted acid catalysis. Herein, a series of pure Lewis acid sites MIL-MOFs (Fe-MIL-100, Fe-MIL-101 and Cr-MIL-101) with different crystal topology structures and metals are synthesized. Then the nanoparticles of Ru, Pt, Pd and Au are uniformly dispersed on the internal surface of the MOF support. The hydrogenation rate catalyzed by the noble metals/Fe-MIL-100 is three times faster than those obtained with Fe-MIL-101 and Cr-MIL-101-based catalysts due to the higher dispersion of nanoparticles on the former to make it more accessible to reactants. Meanwhile, both of the noble metals on Fe-MIL-100 and Fe-MIL-101 have a higher selectivity of cyclopentanone compounds than that on Cr-MIL-101, since the Fe ions in the MOF host with a higher oxophilicity will promote the adsorption and hydrolysis of the intermediate furanic alcohols (furfural alcohol or 2,5-bis(hydroxymethyl)furan). Furthermore, the noble metals/MIL-MOFs catalyst can maintain a good activity and stability after recycling for five runs. The current work will present an efficient catalytic reaction system for the hydrogenative ring-rearrangement of furfural and 5-hydroxymethyl furfural to synthesize cyclopentanone compounds.