DFT Study Of Catalytic Hydrogenation Of 2-butyne-1,4-diol On Ni,Pd,Pt Surfaces

Hydrogenation of 2-butyne-1,4-diol has industrially great importance for manufacturing cis-2-butene-1,4-diol and butanediol.Cis-2-butene-1,4-diol is a very important raw material for vitamin A&B6,and insecticide thus 2-butene-1,4-diol has huge value in pharmaceutical industries.Cis-2-butene-1,4-diol is the product of the first hydrogenated stage of 2-butyne-1,4-diol hydrogenation,immediately goes for further hydrogenation to produce 1,4-butanediol and that is why it is very difficult to achieve the complete selectivity.The 2-butyne-1,4-diol hydrogenation is carried out mostly on Ni-based.Pd-based.and Pt-based catalyst.A good number of experimental works has published to describe the characteristics of 2-butyne-1,4-diol hydrogenation,including the development of new Ni-based,Pd-based,and Pt-based catalyst.On the other hand,very few density functional theory(DFT)investigations are found explaining 2-butyne-1,4-diol hydrogenation.The mechanism is not clear at the molecular level,especially the interaction between reacting agents and atoms of metal-based catalysts.This study aims to make a clear understanding of 2-butyne-1,4-diol hydrogenation at molecular level and compare the catalytic performance of different metals such as Ni,Pd,and Pt,which are usually used as catalyst during the hydrogenation of 2-butyne-1,4-diol.DFT calculations of periodic systems have carried out using CASTEP module within Material studio 8.0 simulation package with the help of generalized gradient approximation(GGA)functional in the form of Perdew-Burke-Ernzerhof(PBE)exchange-correlation functional.Both physical and chemical adsorption of H2 studied on the 111-type surface of Ni,Pd,and Pt at four different adsorption sites such as top,bridge,3-fold hexagonal-closed packed(hcp)hollow and 3-fold face centered cubic(fcc)hollow.No difference was found among various surfaces and metals in terms of physical adsorption.The most stable adsorption was found at bridge site of Pt(111)surface in terms of chemical adsorption.The minimum energy barrier found at Ni(111)surface for dissociative adsorption of H2.The adsorption of the 2-butyne-1,4-diol studied on 111-?110-,and 100-type surfaces of each Ni,Pd,and Pt.The most stable adsorption of the 2-butyne-1,4-diol was found at Ni(111)surface.The maximum increment in bond length at adsorbed 2-butyne-1,4-diol on metal surfaces was observed at C-C triple bond.The transition state along with the reaction energy and the activation barrier of elementary step of addition of one hydrogen atom to activated 2-butyne-1,4-diol on 111 type surfaces of Ni,Pd,and Pt was calculated.The minimum activation barrier was found at Pt(111)surface for the elementary step of addition of one activated hydrogen atom in the absorbed 2-butyne-1,4-diol.