Hydrogenation of Ethylene and Dehydrogenation and Hydrogenolysis of Ethane on Pt(111) and Pt(211): A Density Functional Theory Study

Hydrogenation of ethylene and dehydrogenation and hydrogenolysis of ethane on pt(111) and pt(211) have been studied Using density functional theory (DFT) calculations. Adsorption of CHx and C2Hx species on Pt(111) and Pt(211) has been investigated. All the dehydrogenation and hydrogenation elementary-like reactions of C-2 species, all the C-C bond-cleavage reactions and isomerization reactions between C-2 species have been calculated. The following have been found: (i) CH3C is the most stable C-2 species on Pt(111) and Pt(211); (ii) on Pt(211), ethane dissociation to CH2CH2 and CH3CH is a rapid process at low surface temperatures; (iii) on Pt(111), CH3CH is expected to be rapidly consumed by dehydrogenation to CH3C, which is difficult to be further dehydrogenated to CH2C or hydrogenated to CH3CH (iv) isomerization reactions are not energetically favored on Pt; (v) on Pt(111), the lowest barrier of C-C cleavage is 0.9 eV in CHC, whereas on Pt(211) the lowest barrier of C-C cleavage is 1.1 eV in CH3CH2. These results suggest that at high temperatures, C-C cleavage call happen most possibly via CHCH, CH3CH, and CH3CH2 intermediates.