Influence of furanic polymers on selectivity of furfural rearrangement to cyclopentanone

• Furfural is selectively rearranged to cyclopentanone.
• High selectivity is attributed to furfuryl alcohol polymers.
• The polymers are formed on catalyst surface by side-reaction.
• Modified catalysts inhibit cyclopentanone hydrogenation.
• Desorption of cyclopentanone is responsible for high selectivity.

The influence of furanic polymers upon the activity and selectivity of Ni, Pd, Pt catalysts in rearrangement of furfural to cyclopentanone, and its consecutive hydrogenation to cyclopentanol in an aqueous phase has been studied. The coverage of surface of heterogeneous catalyst by the furanic polymers suppresses or almost completely inhibits hydrogenation of cyclopentanone to cyclopentanol. Furanic polymers are created on catalyst surface by partial polymerization reaction of furfuryl alcohol which is in aqueous medium catalyzed by H+ protons formed by dissociation of water at reaction temperatures. Thermogravimetric and XPS measurements confirmed the presence of polymers on catalyst surface. Owing to the modification of catalyst surface by the polymer bearing furan moieties constituents the dominant reaction product is despite high reaction temperature (175 °C) and hydrogen pressure (80 bar), cyclopentanone, and not expected more stable cyclopentanol. Very high selectivity of furfural rearrangement to cyclopentanone can be achieved by influencing the balance between the rates of formation of furfuryl alcohol polymers on the catalyst surface and their decomposition.

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