1-氯-2-丙醇在銅(100)和氧/銅(100)表面上的熱反應研究

Abstract

The thermal chemistry of 1-chloro-2-propanol (ClCH2CHOHCH3) on a Cu(100) single crystal, with a bare or oxygen-precovered surface (O/Cu(100)), was studied with temperature-programmed reaction/desorption (TPR/D) and X-ray photoelectron spectroscopy (XPS) and reflection-absorption infrared spectroscopy (RAIRS). When 1-chloro-2-propanol is adsorbed on Cu(100) at 120 K, a small portion of the molecules undergo O–H bond scission, but most of them retain intact. On the surface of 240 K, the predominant specie is found to be ClCH2CH(CH3)O–, but there may also have a few oxametallacycles, –CH2CH(CH3)O–. Upon heating to 265K, these intermediates start to decompose to form propene, acetone, CO, CO2 and H2 with residual C and O atoms on the surface, which desorb promptly. The residual carbon and oxygen atoms on the surface react to form CO and CO2 at 510 K. The presence of preadsorbed oxygen promotes O–H bond cleavage of ClCH2CHOHCH3 at 120 K, but suppresses the C–Cl bond dissociation. Only a trace amount of the molecule breaks their C–Cl bonds even at 275 K. On O/Cu(100), the products and surface intermediates detected from ClCH2CHOHCH3 dissociation are similar to those of clean surface. However, a broad desorption peak of H2O is observed at 200 K in contrast to the case of Cu(100).