Adsorption and reactions of ClCH2CH2OH on clean and oxygen-precovered Cu(100): experimental and computational studies.
Temperature-programmed reaction/desorption, reflection-absorption infrared spectroscopy, and density functional theory calculations have been employed to investigate the adsorption and thermal reactions of ClCH2CH2OH on clean and oxygen-precovered Cu(100) surfaces. On Cu(100), ClCH2CH2OH is mainly adsorbed reversibly. The ClCH2CH2OH molecules at a submonolayer coverage can change their orientation with increasing temperature. However, on oxygen-precovered Cu(100), all of the adsorbed ClCH2CH2OH molecules below 0.5 langmuir exposures completely dissociate to generate ethylene and acetaldehyde via the intermediate of ClCH2CH2O-. The computational studies predict that the ClCH2CH2O- is most likely to be adsorbed at the 4-fold hollow sites of Cu(100), with its C-O bond only slightly titled away from the surface normal and with a gauche conformation with respect to the C-C bond. The hollow-site ClCH2CH2O- has an adsorption energy that is 4.4 and 19.2 kcal x mol(-1) lower than that of the ClCH2CH2O- bonded at the bridging and atop sites, respectively. No significant effect of precovered oxygen on the ClCH2CH2O- bonding geometry and infrared band frequencies has been observed, as compared with the case without oxygen.
Fu
Tao-Wei
TW
Department of Chemistry, National Cheng Kung University 1, Ta Hsueh Road, Tainan, Taiwan 701, Republic of China.
Liao
Yung-Hsuan
YH
Chen
Chia-Yuan
CY
Chang
Pei-Teng
PT
Wang
Ching-Yung
CY
Lin
Jong-Liang
JL
D000327:Adsorption; D003198:Computer Simulation; D003300:Copper / Q000737:chemistry*; D005023:Ethylene Chlorohydrin / Q000737:chemistry*; D008956:Models, Chemical; D010100:Oxygen / Q000737:chemistry*; D012680:Sensitivity and Specificity; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013499:Surface Properties; D013696:Temperature
D005023:Ethylene Chlorohydrin; D003300:Copper; D010100:Oxygen