Bio-catalytic degradation of dibenzothiophene (DBT) in petroleum distillate (diesel) by Pseudomonas spp.

Abstract

Biodesulfurization (BDS) was employed in this study to degrade dibenzothiophene (DBT) which accounts for 70% of the sulfur compounds in diesel using a synthetic and typical South African diesel in the aqueous and biphasic medium. Two Pseudomonas sp. bacteria namely Pseudomonas aeruginosa and Pseudomonas putida were used as biocatalysts. The desulfurization pathways of DBT by the two bacteria were determined by gas chromatography (GC)/mass spectrometry (MS) and High-Performance Liquid Chromatography (HPLC). Both organisms were found to produce 2-hydroxy biphenyl, the desulfurized product of DBT. Results showed BDS performance of 67.53% and 50.02%, by Pseudomonas aeruginosa and Pseudomonas putida, respectively for 500 ppm initial DBT concentration. In order to study the desulfurization of diesel oils obtained from an oil refinery, resting cells studies by Pseudomonas aeruginosa were carried out which showed a decrease of about 30% and 70.54% DBT removal for 5200 ppm in hydrodesulfurization (HDS) feed diesel and 120 ppm in HDS outlet diesel, respectively. Pseudomonas aeruginosa and Pseudomonas putida selectively degraded DBT to form 2-HBP. Application of these bacteria for the desulfurization of diesel showed promising potential for decreasing the sulfur content of South African diesel oil.

Hydro-Cracked Light Gas Oil Biodesulphurisation by Immobilised Pseudomonas aeruginosa Cells on Polyvinyl Alcohol

“…Several Pseudomonas species such as P. aeruginosa, P. stutzeri, P. putida, and Rhodococcus species such as R. erythropolis, and R. qingshengii IGTS8, were employed to degrade heterocyclic sulphur compounds [16][17][18][19][20]. Some of these biodegradation processes have low efficiencies which can be attributed to the inability of bacterial cells to be alive for a long time in a toxic aqueous medium of oil-water emulsions in the presence of 2-Hydroxybiphenyl and releases the sulphur content in form of sulphur dioxide [21][22][23].…”

A Nickel-Doped Dehydrobenzoannulene-Based Porous Organic Polymer for the Catalytic Desulfurization of Dibenzothiophenes and Benzothiophenes

“…21 Unlike aryl thioethers, DBTs are not very reactive and they account for the highest percentage of sulfur compounds found in heavy and vacuum gas oil that must be removed to meet environmental standards. 2,16,21,22 Interestingly, Garcia and coworkers have shown that Ni catalysts like [(dippe)-NiH)] 2 are great for the desulfurization of DBTs in the presence of alkyl Grignards. 23,24 While the system is believed to proceed through a classical Ni(0)/Ni(II) pathway, the sulfur gets converted initially to MgS and then to H 2 S after an acidic workup.…”

“…This work highlights a rare example of using a Ni-doped DBA-POP to remove the C−S bonds from refractory sulfur compounds that are commonly found in heavy gas oil and vacuum gas oil. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]21,22 These investigations are necessary for developing innovative desulfurization catalytic systems that are recyclable and efficient at reducing the sulfur content in chemical fuels.…”

“…While this catalytic system was recyclable and great for activating C­(aryl)-S bonds of fused and unfused aryl thioethers, it is still unclear if this Ni(0)-based catalytic system is useful for the desulfurization of dibenzothiophenes (DBTs), a class of refractory sulfur compounds that are commonly found in sour crude oil . Unlike aryl thioethers, DBTs are not very reactive and they account for the highest percentage of sulfur compounds found in heavy and vacuum gas oil that must be removed to meet environmental standards. ,,, Interestingly, Garcia and co-workers have shown that Ni catalysts like [(dippe)-NiH)] 2 are great for the desulfurization of DBTs in the presence of alkyl Grignards. , While the system is believed to proceed through a classical Ni(0)/Ni­(II) pathway, the sulfur gets converted initially to MgS and then to H 2 S after an acidic workup. Although this reaction and other Ni-based catalytic systems − are efficient under homogeneous conditions, it would be cost-effective if this transformation could be achieved under heterogeneous conditions, which would improve the recyclability of the catalytic systems.…”

“…The Ni-DBA-TMT-POP exhibited great recyclability up to five cycles and minimal reduction in catalytic efficiency. This work highlights a rare example of using a Ni-doped DBA-POP to remove the C–S bonds from refractory sulfur compounds that are commonly found in heavy gas oil and vacuum gas oil. − ,, These investigations are necessary for developing innovative desulfurization catalytic systems that are recyclable and efficient at reducing the sulfur content in chemical fuels.…”