Spectroscopic characterization of C2Hx intermediates in the dissociation of vinyl iodide on Pt(111)

Dehydrogenation of Ethylene on Supported Palladium Nanoparticles: A Double View from Metal and Hydrocarbon Sides

“…The one at a lower frequency appears with some delay with the respect to the higher one, and continues growing after ethylene was switched off (see Figure 4 ). The C = C bond can be explained by the formation of vinyl and vinylidene [ 16 , 62 , 63 , 64 ], the former also explains the peak at 1340 cm −1 discussed above related to C-H scissoring (see also Section 3.3 ). This peak was also reported for ethylidyne [ 12 , 14 , 16 ] but absence of C–C stretching near 1100 cm −1 allows us to exclude it.…”

“…The most intense peak observed at 1417 cm −1 (green arrow in Figure 3 ) is shifted to the lower frequencies with respect to C-H scissoring peak of gas phase ethylene. This band may be related to π- or di-σ-adsorbed ethylene [ 16 , 62 , 63 , 65 , 66 ], ethylidene [ 16 , 24 , 62 , 67 ], vinylidene [ 16 ] or methyl group (CH 3 ) [ 19 ].…”

“…In contrast to the adsorption of ethylene and other hydrocarbons over platinum extensively examined by the group of Zaera [ 11 , 12 , 13 ] and numerous other groups [ 8 , 9 , 12 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ], less attention has been paid to ethylene on palladium [ 8 , 9 , 15 , 17 , 20 , 21 , 22 , 23 , 24 ]. In most of these studies, infrared spectroscopy is considered as a main source of information due to sensitivity to surface adsorbed species.…”

Reactions of CH2═CHBr and CH3CHBr2 on Cu(100) and O/Cu(100)

“…The vinyl group further reacts on the surface below 450 K, forming ethylidyne (CH 3 C) and ethylene . Preadsorption of hydrogen is found to enhance the formation of ethylidyne in the reaction of CH 2 CHI on Pt(111) . On Ag(111), decomposition of CH 2 CHI generates 1,3-butadiene (CH 2 CHCHCH 2 ) at ∼250 K, due to self-coupling of two vinyl groups .…”

“…Ethylidene (CH 3 CH) on Pt(111) has been prepared from the facile CI bond cleavage of 1,1-diiodoethane (CH 3 CHI 2 ) . This hydrocarbon fragment is the intermediate in the dehydrogenation process from ethylene to ethylidyne. , In addition to the surface species of CH 2 CH, CH 3 C, and CH 3 CH on Pt(111), the presence of other species, such as HC, H 2 C, and HCC, has been reported, together with their vibrational frequencies . At the 80 K dosing temperature of CH 3 CHI 2 , ethylidene groups form on Ag(111) and dimerize into adsorbed trans-2-butene (CH 3 CHCHCH 3 ) .…”