Theoretical And Experimental Study On Low Cost Hydrogenation Catalyst And Method

Hydrogenation reaction is widely used in petrochemical industries.However,hydrogenation is a high-cost process.In order to reduce the production cost,combining theoretical with experimental mechod,the non-noble metal hydrogenation catalyst and hydrogenation process of light driving are researched and preliminarily explored.In this paper,taking oxidation as the model catalyst,combining the experimental and theoretical calculation,the hydrogenation of linear olefins,cyclic olefins,and aryl nitro groups is investigated.The results show that the hydrogenation activity is depended on oxygen vacancy concentration linearly.Theory calculation show that the surface oxygen defects could activate hydrogen molecular easily.Therefore,WO_2.72with many oxygen vacancies show a higher activity than non-noble metal nickel catalysts.What's more,WO_2.72 show a 100%selectivity for substituted anilines by reducing the NO₂ to NH₂ group because of the vertical adsorption model of nitro compounds on WO_2.72.This work emphasizes the prominent role of oxygen vacancy in H₂ molecular activation,and provides a method for transfering cheap metal oxide to a high activity hydrogenation catalyst by defect engineering.The hydrogenation performance of the nitro aromatic compound and ethylene were researched systematically.For the hydrogenation of the nitro aromatic compound,the activity of the catalyst increases first and then decreases with the increase of the tungsten oxide atom ratio in the tungsten oxides.Among W,WO₂,WO_2.72 and WO₃,WO₂ show the highest catalytic activity.All the selectivity for five substituted aromatic nitro compounds are up to 100%.DFT calculation shows that the adsorption of O atom from the nitro dissociation is a key species of nitrobenzene hydrogenation reaction.Moderate adsorption strength can make the catalyst exhibit a good activity for nitrobenzene hydrogenation.The adsorption strength increased with the increase of W and O ratio.By adjusting the atomic ratio of tungsten oxide can adjust the adsorption strength of O atoms,then a highly active catalyst is got.For ethylene hydrogenation,the similar results were got.However,the adsorption of H₂ dissociation product?2H,ad?is identified as the inherent reason to control the activity of catalyst,and WO_2.72show the best activity.Single atom catalyst has the advantages of both homogeneous catalyst and heterogeneous catalyst.Through DFT calculation,the effect of supporters?C₃N₄ and N-doped graphene?on the activity of ethylene hydrogenation was investigate by theoretical calculation.For CoN₄-graphene,Co atom transfer more electron to N-doped graphene,and combined very intensely.This lead to?2H,ad?adsorbed very weakly,and the activity of CoN₄-graphene is very low.For Co metal,the adsorption of?2H,ad?is very strong,and its activity is also very low.For Co/g-C₃N₄,the number of electron transfer and the combining strength between Co and g-C₃N₄ are appropriate,and the adsorption of?2H,ad?is moderate.Therefore,Co/g-C₃N₄ shows a very high catalytic activity.The production cost is greatly reduced without catalyst in hydrogenation process.By using rich and clean solar resources,coupling the chemical hydrogen storage with the chemical hydrogenation,a hydrogenation method at normal temperature and pressure without catalyst is provided.What's more,the mechanism of this process is analyzed.N₂H₄?H₂O is used as hydrogen source.H radical by situ irradiation react with reaction substrates.The reactant and hydrazine hydrate reacted by stoichiometric ratio,and the utilization efficiency of H in hydrazine was nearly 100%.Theoretical calculation shows that the excitation of the reaction substrate promotes the hydrogenation reaction.This work provides a low cost,high efficiency and green hydrogenation method for large scale hydrogenation of substituted aromatics.