Adsorption and decomposition of formaldehyde on tungsten (100) and (111) crystal planes

Abstract

The chemisorption of formaldehyde at ~100 K has been investigated on two single crystal planes of tungsten, W(100) and W(111). At low H 2CO coverages, only H 2 and CO are observed as thermal desorption products. At higher H 2CO coverages both CH 4 and CO 2 are observed as additional desorption products. Work function and flash desorption measurements indicate that the dissociative adsorption of H 2CO into H(ads) and CO(ads) is accompanied at higher surface coverages by the formation of other surface complexes. A detailed comparison of W(100) with W(111) indicates that crystallographic differences play a minor role in the surface catalyzed decomposition of H 2CO by tungsten.