The ketonization reaction of acetic acid on the (1 0 1) surface of tetragonal zirconia, a process relevant in the catalytic upgrade of cellulosic biomass has been studied by means of DFT+U calculations. The aim was to better understand the role of catalyst pre-reduction. Acetic acid adsorbs strongly on the zirconia surface, and deprotonation to acetate takes place easily. Then, a proton transfer from the methyl group of the acetate ion, CH3COO−, to the surface occurs to form an eno-species, CH2COO2− (intermediate 1). In a parallel step, acetate ions convert into acyl fragments, CH3CO, by oxygen extraction (intermediate 2). Once formed, the acyl intermediate 2 is able to attack the eno-species intermediate 1, to form a β-keto-acid. On stoichiometric zirconia, the formation of the intermediate 1, CH2COO2−, is unfavorable; oxygen vacancies on the reduced surface stabilize the reaction product and strongly reduce the activation energy. Reduced Zr3+ centers are essential to stabilize the acyl intermediate 2. The present work shows at an atomistic level the beneficial role of O vacancies and reduced Zr3+ centers for the ketonization process.

Tosoni, S., Pacchioni, G. (2016). Acetic acid ketonization on tetragonal zirconia: Role of surface reduction. JOURNAL OF CATALYSIS, 344, 465-473 [10.1016/j.jcat.2016.10.002].

Acetic acid ketonization on tetragonal zirconia: Role of surface reduction

TOSONI, SERGIO PAOLO
Primo
;
PACCHIONI, GIANFRANCO
2016

Abstract

The ketonization reaction of acetic acid on the (1 0 1) surface of tetragonal zirconia, a process relevant in the catalytic upgrade of cellulosic biomass has been studied by means of DFT+U calculations. The aim was to better understand the role of catalyst pre-reduction. Acetic acid adsorbs strongly on the zirconia surface, and deprotonation to acetate takes place easily. Then, a proton transfer from the methyl group of the acetate ion, CH3COO−, to the surface occurs to form an eno-species, CH2COO2− (intermediate 1). In a parallel step, acetate ions convert into acyl fragments, CH3CO, by oxygen extraction (intermediate 2). Once formed, the acyl intermediate 2 is able to attack the eno-species intermediate 1, to form a β-keto-acid. On stoichiometric zirconia, the formation of the intermediate 1, CH2COO2−, is unfavorable; oxygen vacancies on the reduced surface stabilize the reaction product and strongly reduce the activation energy. Reduced Zr3+ centers are essential to stabilize the acyl intermediate 2. The present work shows at an atomistic level the beneficial role of O vacancies and reduced Zr3+ centers for the ketonization process.
Articolo in rivista - Articolo scientifico
Density functional theory; Ketonization; Oxide surfaces; Oxygen vacancy; Zirconia;
Density functional theory; Ketonization; Oxide surfaces; Oxygen vacancy; Zirconia; Catalysis; Physical and Theoretical Chemistry
English
465
473
9
Tosoni, S., Pacchioni, G. (2016). Acetic acid ketonization on tetragonal zirconia: Role of surface reduction. JOURNAL OF CATALYSIS, 344, 465-473 [10.1016/j.jcat.2016.10.002].
Tosoni, S; Pacchioni, G
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/149943
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