For Chemical Engineers and Chemical Engineering College students, providing basic idea about biological removal of sulfer present in petroleum distillate.

1. ASHIN V K
TCR15CH014
05/10/2018

2. Outline
 Introduction
 Desulfurization
Definition and techniques
 Biodesulfurization
 BDS process
 Issues in industrial application
 Future perspectives
 Conclusion

3. INTRODUCTION
 SO2 and H2S are the major sources of air
pollution.
 High sulphur level promotes catalyst
poisoning in FCC.
 Can lead to corrosion in pipings and
equipment.
 Causes acid rain.
 Result in health issues, like heart diseases,
asthma, and respiratory illnesses.
 To meet environmental regulations.

4. Desulfurization
Definition
 It is the removal or reduction of Sulphur level in
distillates in order to meet the required
standard.
Existing technologies
 Hydrodesulfurization (HDS)
 Adsorptive desulfurization (AD)
 Oxidation desulfurization (DO)

5. 1. Hydrodesulfurization (HDS)
A metal catalyst is used along with hydrogen gas (H2) to
release H2S at elevated temperature and pressure.
2. Adsorptive desulfurization (AD)
Using adsorbing agents which have an affinity to adsorb sulfur
containing compounds.
3. Oxidation desulfurization (DO)
Involves the use of oxidizing agents such as; H2O2, H2SO4,etc. to
oxidize sulfur containing compounds to sulfone.

6. BIODESULFURIZATION
 Biological method for desulfurization of
ring compounds of sulfur.
 Nondestructive pathway in the mild
conditions.
 Potentially used as complementary with
HDS.

7. Hydrodesulfurization
1. At elevated temperature
and elevated pressure
2. Expensive and poor
energy efficiency
3. Some heterocyclic
sulfur containing
compounds like DBT
are recalcitrant
4. Environmental issues
Biodesulfurization
1. At an ambient temperature
and pressure
2. Low energy cost
3. Removes recalcitrant
sulfur compounds.
4. Low emission of unwanted
products

8. BDS Process
(i) Production of active resting cells
(biocatalysts) with a high specific activity.
(ii) Preparation of a biphasic system containing oil
fraction, aqueous phase and biocatalyst.
(iii) Biodesulfurization of a wide range of organic
sulfur compounds at a suitable rate.
(iv) Separation of desulfurized oil fraction,
recovery of the biocatalyst and its return to the
bioreactor.

10. BDS Pilot Plant

11. BDS Pathways.
Major pathways:
1. The carbon skeleton of DBT is partially
oxidized, with the C-S bond remaining
intact (Kodama pathway).
2. DBT is desulfurized and the carbon
skeleton remains intact ( 4S pathway).

13. Issues in Industrial
Application
1.Costs of microorganisms.
2.Rate of transfer of DBT from oil phase
into microbial cell is also hindered.
3. Dissolved oxygen concentration
becomes the limiting factor.

14. Future Perspectives
 Refinery challenges
The refiners are, required to produce a high
quality diesel product such as ultra-low sulfur diesel
from lower quality feedstocks.
 Research needs
Some key research needs for improving
biocatalysts for an efficient and commercial BDS process
for petroleum and its fractions are the design of
engineered cells with,
(1) Higher specific catalytic activity
(2) Activity for a long period of time
(3) Higher thermal tolerance

15. CONCLUSION
 The most attractive option at present for
the industrial application of the BDS
process in deep desulfurization is to
integrate it with existing HDS units in the
refineries.
 The operations costs will be reduced.
 The process economics will be improved.

16. .Thank you.