Removal of Sulfur from Diesel Fuel

Probably all vehicle owners heard at least once in their life that sulfur has a negative impact on diesel fuel.  But if you ask what exactly is this impact, not all of them will know the answer.  So, why is  sulfur so harmful?

First of all, it promotes fuel oxidation causing environmental pollution with exhaust gases.  But the effect of sulfur on diesel fuel does not only bring negative consequences.  It improves the lubricating properties of this oil product, thereby reducing wear of engine structural parts.  Therefore, when choosing fuel, it is advisable to find a “middle ground”, which on the one hand would provide sufficient lubricity, and on the other hand would minimize environmental damage.  Experts recommend buying fuel with a sulfur content of 0.15 to 1.5%.

In our time the refining industry mainly uses physico-chemical and chemical methods of desulfurization of diesel fuels.  A chemical approach involves the use of hydrotreating and purification with sulfuric acid and physico-chemical method involves absorption and adsorption purification.

Sulfuric acid cleaning is performed by mixing the processed diesel fuel with 90-93% solution of sulfuric acid at ambient temperature.  After all chemical reactions are complete, purified oil and acid sludge are obtained.  The latter contains all the undesirable impurities.  Theoretically, it can be used for production of sulfuric acid.  In general, sulfuric acid treatment is quite complex and requires bulky equipment.

Hydrotreating is the most common method for removing sulfur from diesel fuel as of today.  This process is very expensive.  The cost of hydrotreating units depends on the performance and the required depth of processing, and in theory it can reach millions of US dollars.

The essence of this approach is based on the interaction of hydrogen with diesel fuel in the presence of specific substances, catalysts.  As a result of chemical reactions between hydrogen and sulfur, nitrogen and oxygen compounds, we get hydrogen sulfide, ammonia and water, respectively.  This method also has its disadvantages, which manifest themselves in the form of high temperature (380-420ºC) and pressure (up to 4 MPa) of the process, as well as hardware design complexity.

But in the present conditions, the biggest drawback is perhaps a great anthropogenic impact on the ecological system due to emissions of harmful substances into the atmosphere and waste water.  To neutralize the emissions caused by hydrotreating of petroleum products, additional financial and material expenses are required.

Adsorption treatment is implemented by diesel fuel contact with special adsorbents, which can be bleaching clay or silica gel.  They absorb oxygenated, sulfur and nitrogen compounds as well as other substances, which need to be removed (for example, resin).

Absorption treatment involves selective removal of harmful components of diesel fuel.  Furfural, sulphovin, nitrobenzene are used as solvents. The disadvantage of this approach is the inability to recover the used solvent and, as a result, its total loss causing increased financial costs.

GlobeCore offers eco-friendly technology that allows to remove hydrogen sulfide compounds and to lower sulfur content in diesel fuels.  It is implemented in UVR-type plants, which are also capable of lowering wax content and removing unsaturated hydrocarbons from oil products.  After purification by GlobeCore plants, diesel fuel again becomes marketable, does not re-oxidize and does not darken.

UVR plants have the following advantages:

  • Due to the possibility to choose an automatic or a semi-automatic mode the process does not require constant presence of an operator.  It is only required when starting and stopping the plant and replacement of adsorbents;
  • Low energy consumption;
  • Versatility of application. UVR-type plant does not require any complex manipulation when changing the type of the cleansed, lightened or recovered fuel, or mineral oil.  To change one raw material for another one it is enough to stop the plant, switch to manual mode, pump out residues of petroleum from the system and replace the used adsorbent and filter.



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