Density Functional Theory Study Of Methanol Steam Reforming Produce Hydrogen Reaction Mechanism

Because of high hydrogen production rate and low carbon monoxide concentration, methanol steam reforming produce hydrogen reaction is considered an excellent method that prepared the hydrogen source of fuel cells. To look for the catalyzers with high activation at low temperature, high-selectivities and high stabilities are always the focus in experimental researches. The transition metals play a vital part in this catalytic reaction process. The mechanism of methanol steam reforming reaction is still ambiguous because of the restrictions on present experimental apparatuses, the lack of a theoretical foundation, resulting in catalyst design spent a great deal of time, manpower, material and financial resources.Therefore, in this thesis, Dmol³, a program module based on density functional theory for quantum-mechanical calculation has been utilized to investigate this reaction process, it is helpful to the design of catalyst. The periodic slab model of Pd(111) has been designed. The stability adsorption location, geometries and adsorption energies of species are obtained by the geometry optimization. Mulliken population analysis results were cited to analyze electronic transfer information between adsorbate and substrate. The transition state was searched by the Complete LST / QST method. The activation energy barriers and reaction heat data of elementary reaction steps are obtained.In addition, we also design Cu(111) slab model and study the mechanism of water gas shift reaction has possible existence for methanol steam reforming process. Focus on analyzing three possible micro-mechanisms of the water-gas shift reaction.Comparing the activation energy barriers of multiple paths and on the basis of transition state theory which the reaction tends to go the way of lower energy barrier. Results showed that the main route of methanol steam reforming reaction on Pd(111) surface is via CH₃OH(s)→CH₃O(s)→CH₂O(s)→CHO(s)→CO(s), CO(s)+O(s)→CO₂(s); the main route of water gas shift reaction on Cu(111) surface is via CO(s)+OH(s)→COOH(s), COOH(s)+OH(s)→CO₂(s)+H₂O(s).