Synthesis Of Alkyl Amantadane From Phenanthrene Hydroisomerism

Adamantane is an important part of high energy density fuel,whose substituted compound-alkyl adamantane has excellent low temperature performance and can promote the dissolution of solid components.It can be directly used as the main body or additive of high energy density fuel.Coal tar contains more than 70%of hydrocarbons,some of which are polycyclic aromatic hydrocarbons（naphthalene,anthracene,phenanthrene,etc.）,can be usd to synthesize high energy density fuel.Phenanthrene is a kind of polycyclic aromatic hydrocarbon with high content（>5%in coal tar）but low utilization value.The hydrogenated aromatic perhydrophenanthrene obtained from phenanthrene hydrogenation can be isomerized to alkyl adamantane under acid equilibrium condition.In order to realize the high quality utilization of phenanthrene to alkyl adamantane conversion,a series of bifunctional catalysts were prepared by using USY molecular sieve with mesoporous supercage structure as support and Pt,Pd as active components with excellent low temperature hydrogenation performance,Under the optimum reaction conditions,the activity and mechanism of the catalyst were preliminarily explored.The main research are as follows:firstly,the effects of metal active sites and support acidic sites on phenanthrene conversion and hydroisomerization product distribution were studied,and the whole reaction network was summarized;Secondly,using the saturated product perhydrophenanthrene as raw material,the rate control steps in the conversion of phenanthrene to alkyl adamantane were explored.The main results and conclusions are as follows:1,Preparation of Pt/USY catalyst.Pt/USY catalyst was prepared by equal volume impregnation,in which the support USY has a surface area of 700 m²·g^-1,pore size of 3.8 nm,and Pt particles highly dispersed on USY supercage molecular sieve.2,phenanthrene catalytic hydrogenation reaction performance.At 280°C,4 MPa,the yield of alkyl adamantane was the highest 6.1%when the Pt loading was 1.5 wt%..The analysis of products show that hydrogenation takes place at the metal active sites,isomerization and cracking take place at the acid sites.The phenanthrene is hydrogenated and saturated to perhydrophenanthrene,and then perhydrophenanthrene is converted to alkyl adamantane through isomerization rearrangement.The conversion rate of phenanthrene was affected by the hydrogenation activity of the catalyst.The saturated products,perhydrophenanthrene and perhydroanthracene,are intermediate products in the conversion of phenanthrene to adamantane.The suitable acidity and unique pore structure of USY are the main reasons for the isomerization of perhydrophenanthrene to alkyl adamantane.3,Preparation of Pt-Pd/USY catalyst.Pt-Pd/USY catalysts were prepared by different impregnation methods in order to further improve the hydrogenation activity of the catalysts.Compared with Pt/USY catalyst,Pt-Pd/USY catalyst has higher activity,and its conversion rate of phenanthrene is faster in the same reaction time.The yield of alkyl amantadane was increased from 4.6%to 6.7%,but more intermediate products were cracked due to the strong acidic potential of the carrier.4.Balancing competitive responses.in order to strengthen isomerization reaction and reduce cracking side reaction,USY zeolite was treated with oxalic acid of different concentrations to adjust its acid sites.Results show that the acid strength of USY zeolites after dealumination with oxalic acid decreases,the number and number of acid sites decrease,and the specific surface area and pore structure of USY zeolites also change.In particular,the number of micropores,mesopores and the specific surface affect the dispersion of active metal Pt and the product distribution of phenanthrene catalytic hydrogenation.Isomerization and cracking reactions mainly take place on the acidic sites of Pt/USY support,and the cracking reaction can be weakened and the isomerization reaction can be strengthened by acid treatment of USY support.The hydroisomerization of phenanthrene over Pt/0.1-USY catalyst was the best.The main isomer was perhydroanthracene with a yield of 17.6%,and the yield of alkyl adamantane was 2.3%.Under the same reaction conditions,the yield of alkyl adamantane was8.0%with perhydrophenanthrene as raw material,while the yield of alkyl adamantane was 6.7%with phenanthrene as raw material,indicating that the conversion of perhydrophenanthrene to alkyl adamantane is a rate controlling step of the whole reaction.