Molecular Simulation On The Formation Mechanism Of Vinyl Acetate In The Reaction Of Acetylene With Acetic Acid Catalyzed By Zinc Acetate Supported Over Ordered Mesoporous Carbon

Vinyl acetate is an important organic material which is widely used in chemical industry.Vinyl acetate can be produced through ethylene method and acetylene method.As China has abundant coal resource while lack of petrol,carbide acetylene method is the major production method.At present,the industrial catalysis is Zinc Acetate/Activated carbon.Although this method has been applied for many years,many details,especially the formation mechanism of vinyl acetate are still up for debate.In this work,we proposed to replace activated carbon with ordered mesoporous carbon(OMC).The adsorption properties of reactants were discussed using DFT.Based on these,the reaction mechanism of vinyl acetate were investigated.First,we built the model of catalysis.In order to understand the effect of functional groups on the reaction,carboxyl,carbonyl and hydroxy were used to modify the catalysis support respectively.After analyzing adsorption energy and PDOS,we could could find that functional groups,especially carboxyl,can intense the interaction between zinc acetate and support.Zinc acetate on carboxyl modified OMC is easier to activate reactants because of a lower molecular orbital gap.Second,we investigated the adsorption properties of acetylene and acetic acid on catalysis with different surface structures.After calculation,we could find that on all of the four catalysis,acetylene adsorbed physically while acetic acid chemically.Finally,we discussed the formation mechanism of vinyl acetylene on catalysis with different surface structures.After calculation,we could find that carboxyl would decrease the activation barriers of rate-limiting steps of each mechanism,while hydroxy and carbonyl would increased the barrier to some extent.We could also find that the activation barrier of the first step of acid catalysis mechanism were rather high,with a value of about 5eV.Thus,although activation barriers of another steps were low,this mechanism was hard to take place.The barriers of elementary steps of Peter Kripylo mechanism were lower and exothermic,therefore,this mechanism was preferable.