1995 Volume 74 Issue 2 Pages 109-113
Capture and recovery of nitrogen compounds in methylnaphthalene oil are examined using 10 wt% Al2 (SO4) 3/SiO2 as a solid acid in the fixed bed with a supercritical CO2 extraction apparatus . Model methylnaphthalene oil (quinoline and isoquinoline: 8wt%; 1- and 2-methylnaphthalenes: 42wt%) of 3 .2g was charged into the extraction vesssel under the supercritical CO2 (50°C, 80atm) flow of 6 1/min to pass through the fixed bed of the adsorbent (3 .3g). No nitrogen compounds was eluted until the extraction time of 120 min, while 62% of the fed methylnaphthalene was recovered. Regeneration and repeated use of the solid acid were achieved by purging the adsorbed nitrogen compounds almost completely with higher pressure (150atm) CO2 for 60 min followed by the extraction including methanol as an entrainer solvent for about 30 min, recovering the concentrated quinoline bases . The adsorption capacity of the solid acid gradually decreased with the repeated number of adsorption/desorption cycle probably due to small amounts of nitrogen compounds strongly adsorbed and water on the adso rbent. More polar and/or dry entrainer solvents should be designed for a completely reversible adsorption/desorption procedure.