Structure sensitivity of double bond isomerization of butene over MgO surfaces: A periodic DFT study

Using periodic density functional theory calculations, the double bond isomerization of 1-butene to 2-butene over MgO surfaces with and without structure defects is investigated. The basicity of these surfaces was characterized by the adsorption of H2O and CO2. The isomerization process involves two steps: (i) the abstract of H atom from 1-butene to form chemisorbed 2-butenide with allyl group and (ii) the attack of H atom on such species to form 2-butene. It is found that the isomerization barrier is lower over the stepped surface than on the flat surface and kinked sites. The modification of the surface structure to increase the content of stepped sites is thus one of the ways to improve the isomerization activity of double bond in butene.