Kinetics of n-Butanol Partial Oxidation to Butyraldehyde over Lanthanum–Transition Metal Perovskites

Abstract

Partial oxidation of butanol to butyraldehyde over a series of LaBO 3 (B = Mn, Fe, and Co) perovskites was investigated in a continuous fixed-bed system under ambient pressure. Physicochemical properties of catalysts were characterized by X-ray diffraction, H 2 temperature-programmed reduction, and temperature-programmed oxidation. LaMnO 3 was more favorable to be reduced and reoxidized than LaFeO 3 and LaCoO 3 . Catalytic results have indicated that all catalysts show similar butanol and oxygen conversions and over 90% butyraldehyde selectivities below 300 °C. Side reactions such as butanol or butyraldehyde combustion could be enhanced at high temperatures. To gain an in-depth understanding of perovskite's chemistry involved, kinetic analysis has been carried out. Eight reaction pathways based on the Mars−van Krevelen redox cycle were proposed. These pathways have been lumped and associated with the Langmuir−Hinshelwood−Hougen−Watson formalism to derive a set of rate equations. Parameter estimation via nonlinear regression of derived rate equations has shown that surface reaction, evolving chemisorbed butanol and oxygen, is probably rate-determining. The estimated activation energy of LaMnO 3 (15.0 kcal/mol) by assuming surface reaction as the rate-limiting step was the lowest among all perovskites. This can be ascribed to the better redox property of LaMnO 3 , thereby decreasing the energy barrier in butanol partial oxidation.

Modelling of a microreactor for the partial oxidation of 1-butanol on a titania supported gold catalyst

“…The activation energy of the main reaction, 1-butanol partial oxidation to n-butyraldehyde, in this work was estimated to be ca. 77 kJ/mol being in the reported range [70]. The simulations performed using the 1D-pseudohomogenous model, with the estimated kinetic parameters using power-law and mechanistic kinetic expressions, were successfully able to reproduce the experimental results (Fig.…”

“…The choice of catalyst support material for oxidation reactions in relation to the interaction with the noble metals is essential for final product distribution [65][66][67][68][69]. For the partial oxidation of 1-butanol, different catalyst support materials, such as ZrO2, CeO2, TiO2, AC, Al2O3, SiO2, ASA and perovskites have been employed in both the gas and liquid phases [17,[50][51][52]70]. The TiO2 applied in this work, has shown strong metal-support interaction (SMSI), it is stable at high temperatures and it has a mesoporous structure [61,71].…”

“…A comparison with the literature values was not possible and no data was found for 1-butanol partial oxidation over the Au/TiO2 catalyst. However, Jiang et al [70] summarized that the activation energies of aliphatic alcohols to respective aldehydes (including 1-butanol) are between the region of 10-30 kcal/mol (40-125 kJ/mol). The activation energy of the main reaction, 1-butanol partial oxidation to n-butyraldehyde, in this work was estimated to be ca.…”

Selective oxidation of n-buthanol to butyraldehyde over MnCo2O4 spinel oxides

“…The major products observed are butyraldehyde, propionaldehyde and acetaldehyde while formaldehyde was detected in traces. The n-butyraldehyde yields increased with temperature increasing, reaching a maximum at 200 C then decreasing, probably due to the secondary combustion reactions of butyraldehyde, as observed by Jiang 24 in partial oxidation reaction of butanol to butyraldehyde over a series of perovskites with Mn, Fe and Co. The highest yield in butyraldehyde (37%) was achieved on the rst samples with higher ratio Co/Mn and Co 3+ / Co 2+ (from XPS).…”