Hydrodeoxygenation of furans over Pd-FeOx/SiO2 catalyst under atmospheric pressure

- Pd-FeOx/SiO2 catalyst was found to be highly active for the HDO of furan compounds.
- The presence of iron species restrains the CC cleavage over the Pd/SiO2 catalyst.
- The presence of FeOx decreases the hydrogen pressure requirement for HDO process.
- The synergism effect of Pd and Fe species leads to the high activity of catalyst.

For the first time, the Pd/SiO2 which was modified by FeOx species (Pd-FeOx/SiO2) was reported as an active catalyst for the solvent-free hydrodeoxygenation (HDO) of the aldol condensation product of furfural and methyl-isobutylketone (MIBK). The presence of iron species not only restrains the CC cleavage (decarbonylation and retro-aldol condensation) over the Pd/SiO2 catalyst but also decreases the hydrogen pressure which is needed for the total HDO of aldol condensation product over the Pd/SiO2 catalyst. Compared with the Pd/SiO2 catalyst, the Pd-FeOx/SiO2 catalyst also exhibited higher activity for the HDO of other furan compounds under atmospheric pressure. Over the 5%Pd-2.5%FeOx/SiO2 catalyst, complete conversion of feedstocks and high carbon yields of jet fuel range alkanes (87-94%) can be achieved by the atmospheric HDO of a series of furan compounds at 623 K or 573 K. From the results of XRD, STEM, CO chemisorption, FT-IR, EXAFS, H2-TPR, in-situ XPS and quasi-in-situ Mössbauer spectra, it was noticed that the modification of iron species decreases the coordination number of Pd-Pd on the Pd/SiO2 catalyst, which may restrain the decarbonylation during the HDO process. The presence of Pd promotes the reduction of iron species and the generation of Pd-Fe alloy. Both effects may be the reasons why the Pd-FeOx/SiO2 catalyst is more active than Pd/SiO2 in the solvent-free HDO of furan compounds under atmospheric pressure.

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