Rational Synthesis and Evaluation of Pd Bimetallic Catalysts for Furfural Rearrangement to Cyclopentanone in Aqueous Phase

Furfural, a product of acid-catalysed hydrolysis of hemicellulose in lignocellulosic biomass, is one of most promising biochemical platforms. With multiple active functional groups, furfural (FFA) can be catalytically transformed into a series of chemicals. Cyclopentanone (CPO) is one of downstream products from furfural hydrogenation which is widely used as solvents and fine chemical starting materials for fungicides, fragrances and pharmaceuticals [1]. Production of CPO is a good way to develop further utilization of biomass-based furfural.

Hydrogenation of furfural has been intensively reported in literature, however the rational method to prepare bimetallic catalysts for this reaction hasn’t been covered much. In this work, the aqueous phase hydrogenation of FFA to CPO was investigated on supported bimetallic catalysts (Pd-Ni, Pd-Cu and Pd-Co) prepared by simultaneous Strong Electrostatic Adsorption (SEA) and incipient wetness (IW). In SEA method, hydroxyl groups populate on the surface of support are charged by adjusting pH value in the solution away from its neutral point which is termed as Point of Zero Charge (PZC), metal precursors with opposite charges will be adsorbed. Unlike incipient wetness, the strong electrostatic interaction between metal complexes and supports renders highly dispersed metal nanoparticles. X-ray diffraction, elemental mapping and H₂ chemisorption were performed to confirm the high dispersion (<1.5 nm) and intimate contact between Pd and second metal.

Furfural hydrogenation reaction was carried out in 57 mL deionized water with 3 g of FFA at 150 ^oC, 500 PSIG (P_H2= 430 PSIG) for 3 hours, products were sampled at an interval of 20 min and analyzed by GC. Reaction results showed enhanced catalytic performance with Pd bimetallics prepared by SEA compared to their IW counterparts: the yield of CPO increased by more than 5 times; nano-alloy survived and slightly sintered (~2.5 nm) in SEA catalysts while Ni and Co might have leached out from IW ones after reaction.

References

[1] M. Hronec, K. Fulajtarove, I. Vavra, T. Sotak et al., App. Cataly. B : Environmental, 181 (2016) 210-219.