Kinetic Modeling of Erythritol Deoxydehydration and Consecutive Hydrogenation over the ReO_x-Pd/CeO₂ Catalyst

Abstract

The reaction kinetics of deoxydehydration + hydrogenation (DODH + HG; didehydroxylation) of erythritol to butanediols and n-butane over the ReO x -Pd/CeO2 catalyst was investigated. Competitive adsorption of polyols and catalyst deactivation during the DODH + HG reaction were necessary to be considered in the kinetics. The order of the adsorption strength on the catalyst surface was erythritol >1,2-butanediol > water >1,4-butanediol and monoalcohols. The deactivation during the reaction was investigated with two models: time-dependent and conversion-dependent ones. The conversion-dependent model better fitted both the activities of reused catalysts and the time-course data. The deactivated catalysts were characterized with TG-DTA and Raman spectroscopy. The weight loss and the temperature for the combustion of deposited organic species in TG-DTA did not correlate with the deactivation degree. On the other hand, a growing signal at around 910 cm–1 was observed in Raman spectroscopy in line with deactivation, which can be explained by the formation of aggregated ReO x species. The low activity of aggregated ReO x species was supported by DFT calculations showing that the activation energy of dimeric Re2O x H y /CeO2 catalyst species for the cleavage of two C–O bonds is higher than that of monomeric ReO x H y /CeO2 species.

Selective hydrogenolysis of furfural to 1,2-pentanediol over a Pt–Fe/MT catalyst under mild conditions

“…The O atom in the furan ring can easily adsorb onto the oxygen vacancy at the interface between Pt and Fe 2+ , which was evidenced by the furan ring opening using furan as the substrate (Table S6†). Probably, the O hydroxyl –C 1 –C 2 –O ring forms a cyclic structure with the Pt–O V –Fe sites, which is relatively stable, as proposed by Tomishige et al 40 When the dissociated H attacks the O on the furan ring, the C 5 –O bond is more prone to breakage and generates 1-hydroxy-2-pentanone, an intermediate that was detected using MS by Mizugaki and co-workers, 1 whereupon the CO group then undergoes rapid hydrogenation to produce 1,2-PeD.…”