The desorption of propylene oxide from oxygen atom and hydroxyl covered Ag(110)

• Published in: Surface science Vol. 401; no. 1; pp. 1 - 11
• Main Authors: Ranney, Jeffrey T, Gland, John L, Bare, Simon R
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.05.1998; Amsterdam Elsevier Science; New York, NY
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry; Hydroxyl groups; Oxygen; Partial oxidation; Propylene oxide; Solid-gas interface; Surface physical chemistry; Water; Propylene oxide; Water; Oxygen; Partial oxidation; Ag; Hydroxyl groups; Gas solid adsorption; Silver; Propene; Gas solid desorption; Coadsorption; Gas solid interface; Thermodesorption; Oxidation; Experimental study; Hydroxyl
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(97)00880-7

Coadsorbed water decreases the desorption temperature for propylene oxide on the oxygen covered Ag(110) surface. On oxygen atom covered Ag(110), the desorption activation energy of propylene oxide increases by up to 30% with increasing oxygen coverage relative to clean Ag(110). When propylene oxide is desorbed from a hydroxyl covered surface [generated by water adsorption on oxygen atom covered Ag(110)], the desorption temperature and activation energy decrease when compared to the oxygen covered surface. On the oxygen precovered Ag(110) surface, the maximum propylene oxide desorption rate occurs at 208 K with a desorption activation energy of 12.5 kcal/mol, while on the same oxygen precovered surface, coadsorption of water reduces the temperature of the propylene oxide desorption rate maximum to 194 K and the activation energy to 11.6 kcal/mol. In the absence of preadsorbed oxygen, no reaction or significant interaction is observed between coadsorbed water and propylene oxide. The desorption spectra and peak temperatures are the same as observed for adsorption/desorption from clean Ag(110). The water induced reduction in the propylene oxide heat of desorption from O–Ag(110) may increase the propylene oxide desorption rate and limit secondary reactions, leading to the enhanced propylene oxidation selectivity observed when water is added to the reactor feed gases.