Molecular Simulation Study On Preparation Of Pd Catalysts For Direct Synthesis Of Hydrogen Peroxide From Hydrogen And Oxygen

The direct synthesis of H₂O₂ from H₂ and O₂ conforms to the sustainable development of green technology with high atom economy and has none pollution of environmental in synthetic process.At present,Pd is the most effective catalysts for direct synthesis of hydrogen peroxide.The deep analysis of the catalysts from the atomic and molecular level could provide theoretical guidance to develop high selective catalyst used in direct synthesis of hydrogen peroxide hydrogen.In this paper,the molecular simulation software was used to construct Pd unit cell models,and H₂,O_2,H₂O,H₂O₂ molecular model.Using the density functional theory in the quantum chemistry simulation calculates the electronic characteristics of different Pd crystal plane and explores the catalytic performance of the direct synthesis of H₂O₂from H₂ and O₂ of different surface.At the same time,molecular dynamics method and Monte Carlo method were used to investigate the adsorption performance of H₂,O_2,H₂O and H₂O₂ on different Pd crystal plane.In the three crystal plane of Pd（111,110,100）,d band has the most electrons of all partial density of states,according to energy band theory and valence-bond theory come to a conclusion that the Pd has good catalytic activity.Charge number of each crystal has the following relationship between Pd（111）>Pd（100）>Pd（110）and energy relation of each crystal is Pd（111）<Pd（110）<Pd（100）,so the Pd（111）’s catalytic properties superior to the other two directions because its electron density is one of the biggest and energy is the minimum.Fukui function value has the following relationship between Pd（111）>Pd（100）>Pd（110）,so Pd（111）is also the best.At temperature 298K and pressure 1¹00kPa,single-component average adsorption quantity of H₂,O_2,H₂O and H₂O₂ on different Pd crystal plane has the following relationship between H₂<O₂<H₂O<H₂O₂,and Pd（110）>Pd（100）>Pd（111）,while the corresponding average of adsorption heat trend is reduced in turn.Under the same conditions of temperature and pressure,multi-component adsorption situation in accordance with single-component,only the average adsorption quantity reduced due to the competitive adsorption between each material.Although each material average adsorption quantity on the Pd（111）crystal plane is not the most,but the corresponding average adsorption heat is biggest,which indicates that its adsorption force is stronger than others.Pd（111）crystal plane has a better effect in the process of the direct synthesis of H₂O₂ from H₂ and O₂ based on analysis of above.