期刊
SURFACE SCIENCE
卷 604, 期 19-20, 页码 1558-1564出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.susc.2010.05.025
关键词
Ethanediol; 1,2-Propanediol; Propylene glycol; Palladium; Biorefining; Biomass; Polyols; Vibrational spectroscopy
资金
- National Science Foundation [CBET-0828767]
- Department of Education Graduate Assistantships in Areas of National Need (GAANN)
- Div Of Chem, Bioeng, Env, & Transp Sys
- Directorate For Engineering [0828767] Funding Source: National Science Foundation
The reactions of ethylene glycol and 1,2-propanediol have been studied on Pd(111) using temperature programmed desorption (TPD) and high resolution electron energy loss spectroscopy (HREELS). Both molecules initially decompose through O-H activation, forming ethylenedioxy (-OCH2CH2O-) and 1,2-propanedioxy (-OCH2CH(CH3)O-) surface intermediates. For ethylene glycol, increases in thermal energy lead to dehydrogenation and formation of carbonyl species at both oxygen atoms. The resulting glyoxal (O HCH O either desorbs molecularly or reacts through one of two competing pathways. The favored pathway proceeds via C-C bond scission, dehydrogenation, and decarbonylation to form carbon monoxide and hydrogen. In a minor pathway, small amounts of glyoxal undergo C-O bond scission and recombination with surface hydrogen to form ethylene and water. The same reaction mechanism occurs for 1,2-propanediol after methyl elimination and formation of glyoxal. However, this is accompanied by a minor pathway involving a methylglyoxal (O=CHC(CH3)=O) intermediate. The prevalence of the dehydrogenation/ decarbonylation pathway in the current work is consistent with the high selectivity for C-C scission in the aqueous phase reforming of polyols on supported Pd catalysts. (C) Elsevier B.V. All rights reserved.
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