UN SDG
Call for SR&TD Project Grants - 2017
€239.815,03
 New Biocatalysts for Green Crude Oil Desulfurization
Pedro Manuel Azevedo Alexandrino Fernandes
REQUIMTE - Rede de Química e Tecnologia - Associação
Chemical Sciences
Biological Sciences
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THE PROBLEM
Petroleum (crude oil) contains a vast amount of sulfur [1], causing corrosion in refinery equipment [2, 3] and SO2 emissions, which give rise to acid rain and adverse respiratory effects on man [3, 4]. As a result, strict restrictions to the sulfur content in fuels have been put in place [3].
The standard desulfurization technology is HYDROdesulfurization. It runs at high temperature (200-425 °C) and pressure (150-250 psi), and it is not very efficient for producing ultra-low sulfur fuels, due to the difficulty in removing sulfur from dibenzothiophenes (DBTs), which represent ~60 % of the total sulfur content. It also produces H2S, a toxic and corrosive gas [3, 5, 6], and massive CO2 emissions [7]. The cost of HYDROdesulfurization of diesel fuel reaches tens of billions of dollars per year worldwide [8]. A replacement is deemed needed.

THE GOAL AND THE VISION
BIOdesulfurization, which employs bacteria to clean sulfur, is nowadays the best alternative to HYDROdesulfurization. It is much less expensive [8] and drastically reduces CO2 emissions [3]. However, it is not ready for technology transfer because it is still too slow for industrial standards.
The goal and vision of this project is to improve the BIOdesulfurization performance to meet the standards of oil refinery plants.
The long-term vision is to replace a part of the HYDROdesulfurization process by BIOdesulfurization, in the petroleum refinery industry.

THE STRATEGY
BIOdesulfurization employs bacteria that use DBTs as source of sulfur through the ?4S metabolic pathway? (details in Fig. 1 - see attachments) [3, 5, 9]. It involves four enzymes working at room temperature and pressure [10].
We want to improve the 4S pathway through a coupled computational/experimental methodology. In the past we have used high-level quantum mechanics to predict enzymatic mechanisms [11-14] and the origin of the enzymes catalytic power [15]. We will use now that knowledge to improve the 4S metabolic pathway. X-ray crystallography will also be used to unravel fine details of the 4S pathway.

EXPECTED RESULTS
Our expected result is to make BIOdesulfurization faster by 500-fold, and ready for technology transfer after having patented the results. This technology can save up to 50% of the enormous costs of sulfur cleaning [19] and significantly reducing its massive CO2 emissions [19].
Enzymatic CatalysisMolecular ModelingQuantum ChemistryX-ray Crystallography