Activation of methyl acetate on Pd(111)
- ORNL
The absorption and activation of methyl acetate (CH{sub 3}COOCH{sub 3}), one of the simplest carboxylic esters, on Pd(111) have been studied using self-consistent periodic density functional theory calculations. Methyl acetate adsorbs weakly through the carbonyl oxygen. Its activation occurs via dehydrogenation, instead of direct C-O bond dissociation, on clean Pd(111): It is much more difficult to dissociate the C--O bonds ({epsilon}{sub a} ? 2.0 eV for the carbonyl and acetate-methyl bonds; {epsilon}{sub a} = 1.0 eV for the acetyl-methoxy bond) than to dissociate the C-H bonds to produce enolate (CH{sub 2}COOCH{sub 3}; {epsilon}{sub a} = 0.74 eV) or methylene acetate (CH{sub 3}COOCH{sub 2}; {epsilon}{sub a} = 0.82 eV). The barriers for C-H and C-O bond dissociation are directly calculated for enolate and methylene acetate, and estimated for further dehydrogenated derivatives (CH{sub 3}COOCH, CH{sub 2}COOCH{sub 2}, and CHCOOCH{sub 3}) based on the Bronsted-Evans-Polanyi linear energy relations formed by the calculated steps. The enolate pathway leads to successive dehydrogenation to CCOOCH{sub 3}, whereas methylene acetate readily dissociates to yield acetyl. The selectivity for dissociating the acyl-alkoxy C-O bond, which is desired for alcohol formation, is therefore fundamentally limited by the facility of dehydrogenation under vacuum/low-pressure conditions on Pd(111).
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF); Oak Ridge National Laboratory (ORNL); Center for Nanophase Materials Sciences
- Sponsoring Organization:
- DOE Office of Science; ORNL work for others
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 981426
- Journal Information:
- Surface Science, Journal Name: Surface Science Journal Issue: 11-12 Vol. 604; ISSN SUSCAS; ISSN 0039-6028
- Country of Publication:
- United States
- Language:
- English
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