Surface Science 459 (2000) 149–160 www.elsevier.nl/locate/susc Reaction of CH 2 with adsorbed O on Ru ( 001 ) surface A. Kis, J. Kiss, F. Solymosi * Institute of Solid State and Radiochemistry, University of Szeged, and Reaction Kinetics Research Group of the Hungarian Academy of Sciences1, P.O. Box 168, H-6701 Szeged, Hungary Received 15 January 2000; accepted for publication 30 March 2000 Abstract The reaction pathways of CH 2 in the presence of coadsorbed oxygen atoms on Ru(001) surface were investigated by means of temperature-programmed desorption ( TPD), photoelectron spectroscopy ( XPS and UPS ) and work function measurements. CH 2 species were produced by thermal and photoinduced dissociation of CH 2 I 2 . Preadsorbed oxygen atoms markedly stabilized CMI bonds, shifted the desorption of CH 2 I 2 to higher temperatures and reacted with CH 2 formed to give formaldehyde above 200 K. Adsorbed formate was also detected in the temperature range of 300–450 K. The oxidation of surface species (CH 2 O, HCOO, C x H y ) proceeded above 450 K, to produce CO, CO 2 , and H 2 O. Illumination of the (CH 2 I 2 +O) coadsorbed layer initiated the dissociation of CH 2 I 2 , and induced the reaction of CH 2 with O slightly above 110 K. © 2000 Elsevier Science B.V. All rights reserved. Keywords: Aldehydes; Oxygen; Photochemistry; Ruthenium; Thermal desorption spectroscopy; Ultraviolet photoelectron spectro- scopy; Work function measurements; X-ray photoelectron spectroscopy 1. Introduction In this case adsorbed O did not alter the dominant pathways of the reaction of CH 2 formed above 200 K, e.g., the coupling of CH 2 into C 2 H 4 . The coupling and reactions of hydrocarbon Formaldehyde formation was observed only when fragments (CH 2 , CH 3 ,C 2 H 5 , etc.) with adsorbed CH 2 was produced at 100 K by illumination of oxygen atoms represent important elementary CH 2 I 2 +O/Cu(100) system. steps in the selective and total oxidation of hydro- In a previous paper we gave an account on the carbons and also in the reforming of methane to chemistry of CH 2 I 2 on the Ru(001) surface [10]. produce synthesis gas [1]. Previous works showed The aim of the present work is to elaborate the that CH 2 produced by the thermal and photodisso- primary interaction of adsorbed CH 2 with atomi- ciation of adsorbed CH 2 I 2 on Pt(111) [2], Rh(111) cally adsorbed O on Ru(001) surface and to [3–7] and Pd(100) [8] surfaces is readily combined determine the routes of subsequent reactions in with adsorbed oxygen atoms to give CH 2 O which the coadsorbed layer. Unlike other platinum is released in the gas phase after its formation. metals, Ru is an excellent catalyst for the synthesis Di erent results were obtained for Cu(100) [9]. of higher hydrocarbons, but it is markedly less active and selective in the production of * Corresponding author. Fax: +36 62 322 378. oxygenated hydrocarbons. Therefore, it was inter- E-mail address: fsolym@chem.u-szeged.hu ( F. Solymosi) esting to see its e ect on the coupling of CH 2 1 This laboratory is a part of the Center for Catalysis, Surface and Materials Science at the University of Szeged. with O. 0039-6028/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved. PII: S0039-6028(00)00462-3