Research And Preparation Of Hydrogenation Conversion Catalyst For Liquid Hydrogen Storage Materials Of Polycyclic Aromatic Hydrocarbons

Polycyclic aromatic hydrocarbon molecules treated as organic hydrogen storage materials.On the one hand,it can alleviate the gap in the demand for raw materials for hydrogen energy storage technology and meet the demand for clean energy for economic development,and on the other hand,it can lighten the crude oil,realize the efficient utilization of heavy oil and improve its added value.Therefore,deep hydrogen saturation of polycyclic aromatic molecules is the key to the preparation of organic hydrogen storage materials.During the ring-by-ring hydrogenation of polycyclic aromatic molecules,the spatial site resistance increases and the reaction rate constant decreases sequentially,to overcome this difficulty,the development of high-performance deep hydrosaturation catalysts is crucial.In this paper,the classical polycyclic aromatic molecular phenanthrene is used as a probe for the hydrogenation reaction.In this paper,Ni-Mo/Al₂O₃ was used as the base catalyst for deep hydrosaturation,and to improve the reactivity and selectivity of the catalyst,the dispersion of the active component on the carrier and the nature of the active phase were regulated by changing the loading of Ni-Mo.The optimal combination of metal loading was determined by combining the results of catalyst characterization and evaluation of the phenanthrene hydrogenation reaction as 4.0 wt.%Ni O-14.3 wt.%Mo O₃.With this catalyst,when the reaction temperature was 300℃and the liquid hourly space velocity was 5 h^-1,the deep hydrosaturated products reached the maximum selectivity and maintained the high conversion rate of 81.74%and 86.87%,respectively.In order to further improve the catalytic reaction activity and hydrogenation reaction depth,the Ni-Mo/Ti O₂-Al₂O₃ series catalysts were synthesized by modifying the single carrier and introducing Ti O₂ while retaining the above optimal metal loading,and the acid properties and surface structure characteristics of the catalysts were modulated by changing the Ti/Al molar ratio in the composite carrier.The results showed that the selectivity of deeply hydrogenated saturated products in the phenanthrene hydrogenation reaction system improved to 84.47%and the conversion of phenanthrene increased to 89.12%at a reaction temperature of 300℃and liquid hourly space velocity of 5 h^-1 under the catalyst of Ti/Al of 1.5.In order to achieve maximum utilization of the hydrogen storage performance of the hydrogen storage media materials,it is required to further improve the selectivity of the deeply hydrogenated saturated products.Ni-Mo/ZSM-5-Al₂O₃ series catalysts were synthesized by introducing mesoporous ZSM-5 molecular sieve with Si/Al molar ratio of 60 and modifyingγ-Al₂O₃ by mechanical mixing.By adjusting the mass proportion of ZSM-5 in the mixed carrier to regulate the pore structure and acid properties,the results showed that the highest selectivity was achieved when ZSM-5 was 20%by mass in the mixed carrier,and under the action of this catalyst,the selectivity of deeply hydrogenated saturated products in the phenanthrene hydrogenation reaction system was further increased to 91.98%at a reaction temperature of 300℃and liquid hourly space velocity of 7.5 h^-1,and the conversion of phenanthrene was as high as 91.00%.In order to reduce the occurrence of cracking reaction and isomerization pathway in the process of phenanthrene hydrogenation,the above catalysts with 20%mass proportion of ZSM-5 and its Si/Al molar ratio were adjusted to synthesize Ni-Mo/ZSM-5-Al₂O₃.The Ni-Mo/ZSM-5-Al₂O₃ catalyst with a silicon-to-aluminum ratio of 130 was used to further increase the saturation selectivity of deep hydrogenation to 95.40%and the conversion of phenanthrene to 96.61%.