Polymerization and decomposition of acetaldehyde on rutherium(001)

Abstract

The polymerization and decomposition of acetaldehyde (CH3CHO) on Ru(001) was studied by high-resolution electron energy loss spectroscopy (HREELS), static secondary ion mass spectrometry (SSIMS), and temperature-programmed desorption (TPD). Evidence is presented that low exposures (<0.4 langmuir) of CH3CHO on Ru(001) at 110 K polymerize across the surface in two dimensions upon adsorption. p'(0) CH3CHO, which is the proposed intermediate in surface polymerization, is stable only at exposures approaching saturation of the first layer (0.4-0.6 langmuir). This species incorporates into the surface polymer after heating above 150 K. Exposures above 0.6 langmuir result in multilayer CH3CHO, which desorbs in TPD at 148 K. A second CH3CHO state appears in TPD at 250 K for CH3CHO exposures above 2 langmuir and is attributed to decomposition of polymerized CH3CHO in three dimensions above the surface. Ions from this polymer, containing at least monomer units, are detected in +SSIMS. The surface polymer decomposes to rj1 2(C,0) CH3CHO after heating above 250 K. Decomposition of the latter species at 315 K evolves H2 in TPD and leaves CO and small amounts of C^H and p2(C,0) CH3CO on the surface.

Acetaldehyde reactions over the uranium oxide system

“…9), is far larger in the UO 2 case. The ν(C-C) vibration has also been seen to be more pronounced for η 2 (C,O) than for η 1 (O) acetaldehyde in other works [26]. Then the large intensity of the 1705 cm −1 peak associated with the small intensity of the 1125 cm −1 peak in Fig.…”

“…First, it reacts to give a high yield of furan on β-UO 3 [21]; furan is a desired product that enters into a wide variety of chemical compounds [24,25]. Second, acetaldehyde is an intermediate molecule that can be easily oxidized or reduced depending on the environment; this is one of the main reasons why acetaldehyde has been studied by several workers over a large number of surfaces including Ru (001) [26], Ag (111) [27], Pt(S)-[6(111) × (100)] [28], Pd (111) [29], Rh (111) [30], SrTiO 3 (100) [31] and TiO 2 (001) [32] single crystals, and SiO 2 [33,34], TiO 2 [32,35], and CeO 2 [36] powders.…”

Initial steps in the production of H2 from ethanol: A FT-IR study of adsorbed species on Ni/MgO catalyst surface

“…acetaldehyde coordinated to metal sites through C and O, which have been found to be formed after acetaldehyde adsorption over Rh, Pd, Ru and Co in metallic or supported form [23,24,25,26], a further explanation could be the formation of surface dioxyethylidene species.…”

Acetaldehyde partial oxidation on the Au(111) model catalyst surface: C–C bond activation and formation of methyl acetate as an oxidative coupling product

“…Furthermore, desorption of MA at 171 K during the reaction of oxygen pre-covered Au(111) with acetaldehyde ( Figure 4) is in perfect agreement with the desorption temperature of chemisorbed MA on the clean Au(111) model catalyst surface as shown in Figure 3. On the other hand, the significant CO desorption signal located at 171 K can be attributed to the decomposition of chemisorbed acetaldehyde species into CO and H 2 (the latter species was not followed in the current TPRS experiments) [36]. This is due to the fact that neither MA nor acetaldehyde species has an intense QMS fragmentation signals at m/z=28.…”

“…It is plausible that during the completion of the first monolayer, two-dimensional (i.e. 2D) polymeric acetaldehyde species [36] may be formed in…”