Modulating Activity and Selectivity of Aqueous Phase Furfuryl Alcohol Hydrogenation by Tuning Supported Pt on W-Zr Mixed Oxides

This work investigated a mixed WxZry oxide supported-platinum catalyst for the selective synthesis of cyclopentanone (CPO) from furfuryl alcohol (FOL). The tuning effect of different W and Zr molar ratio with varying Pt loadings at various operating temperatures and PH2 were explored under aqueous phase conditions in a flow-through configuration. Different WOx domain and Pt0 crystallite sizes were obtained as a function of Zr content in the supports. These modulations exhibited distinct selectivities towards the reaction intermediates. Furthermore, water was found to complement as a source of homogeneous catalysis for FOL rearrangement at high temperatures. Minimal hydrogenation intermediates were detected using only WxZry supports. While the presence of Pt does enhance hydrogenation activity, it also resulted in reduction of WOx domains necessary for reaction steps beyond FOL rearrangement. This effect was found to be more pronounced with increasing W concentration in the supports. Regardless of the catalyst formulation used, increasing PH2 resulted in lower hydrogenation activity. Conducting experiments with catalysts at various synthetic steps led to a comprehensive resolution of the reaction mechanism. A two-step metal induced hydrogenation of the intermediate, 4H2CP, was found to be the slowest step in the reaction network to obtain CPO. This bottleneck could only be overcome by slightly increasing Pt content in the catalyst, resulting in ~ 64% CPO yield and high selectivity for sample with lowest W content. Long-term operation of the catalytic bed demonstrated stable activity for at least 38 hours of continuous operation.