(333g) Integration Study of Adsorption/Bio-Regeneration of Adsorbents for Ultra-Deep Desulfurization
A novel integration of a combined physical-biological procedure was reported for ultra-deep desulfurization of fuels. During this process sulfur compounds are removed through adsorption and then biodegraded in a subsequent stage with Pseudomonas delafieldii R-8 strain, with the regeneration of the adsorbent. Several adsorbents with different adsorption mechanism such as selective adsorption, π-complexation and physical adsorption were selected to study their adsorption properties and bio-regeneration. Reduced NiY was prepared firstly by ion exchanging and then reduced in reducing gas(5% H2 and 95% N2, vol/vol). Adsorbents AgY was prepared by ion-exchanging method. Adsorption properties of reduced NiY, AgY, activated alumina, ZSM-5 and activated carbons were studied with dibenzothiophene (DBT) and naphthalene as model compounds. The reduction behavior of Ni(II)-Y was studied by using temperature programmed reduction (TPR) with reducing gas (5% H2 and 95% N2, vol/vol).The adsorption ability of DBT molecules on the surface of various adsorbents follows the trend: activated carbons>reduced NiY>AgY>activated alumina>ZSM-5. The selectivity of DBT toward naphthalene follows the order: reduced NiY>AgY> ZSM-5> activated carbons. The desorption behavior of DBT were studied with thermalgravity differential thermal analysis (TG-DTA). The bio-regeneration of these adsorbents was studied with Pseudomonas delafieldii R-8 as desulfurization strains. The desorption of DBT from adsorbents by bio-regeneration follows the sequence: ZSM-5>alumina>AgY>reduced NiYµ activated carbon. The effect of aromatics on the bio-regeneration of spent AgY was also studied. The results show that when DBT and naphthalene adsorbed on the adsorbents AgY simultaneously, the desorption of DBT decreases compared with that of the desorption when only DBT adsorbed on the adsorbents. π-Complexation adsorbent AgY was successfully bio-regenerated. Adsorption capacity of the regenerated adsorbent is 90% that of the fresh one after being regenerated with Pseudomonas delafieldii R-8 and calcinated at 500ºC in the air for 3 hr. After bio-regeneration, the adsorbent can be reused. Key Words: Desulfurization, π-Complexation, Adsorption, Pseudomonas delafieldii R-8, Bio-regeneration.