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Hydrotreatment processes


Fuel quality has a significant effect on the emissions produced by cars. It is therefore especially important to reduce a fuel's sulphur in order to minimise vehicle emissions of pollutant gases such as SOx, NOx, CO, etc. With this in mind, Repsol has hydrodesulfurization (HDS) units for diesel, paraffin and naphtha at its production centres.

The hydrotreatment process is mainly used to reduce the sulphur level in fuels in order to protect the environment.

Hydrotreatment processes

In the hydrodesulfurization process, the hydrocarbons react with hydrogen in a catalytic bed at moderate pressure (between 20 and 70 bars) and temperature (between 270 ºC and 400 ºC). The sulphur atoms present in the hydrocarbon molecules combine with the H2 to create hydrogen sulphide (H2S). This gas is later treated with sulphur recovery processes which convert it into elemental sulphur.

The Repsol Technology Centre is equipped with modern hydrotreatment pilot plant facilities for the study and optimisation of the processes and catalysts.

The pilot plants reproduce on a very small scale the processes carried out in industrial plants. The plants are used to research possible improvements for industrial plants with the aim of identifying more efficient alternative technologies in order to bring industrial plants up to the new fuel quality standards.

Therefore using the results obtained in the pilot plant:

  • The most active and stable catalysts are selected according to their application.
  • We can obtain a deeper knowledge of production processes. By applying this knowledge to industrial plants, we can reduce catalyst operation costs as well as energy consumption and consequently CO2 emissions in the atmosphere.
  • We can develop computer applications for industrial unit monitoring, as well as process simulation.
  • Modifications to the production process can be analysed in order to incorporate new raw materials. One example is the co-processing of vegetable oil with mineral diesel in the existing hydrodesulfurization units.           

As well as the fuel hydrodesulfurization units, other hydrotreatment processes with different objectives are carried out in the refineries: reduction of benzene content in gasoline, improvement of organoleptic properties (colour, smell, etc.) or improvement of the product's stability.

A good example are the processes of selective hydrogenation of intermediate products (ethylene, propylene, butadiene and benzene) that serve as raw materials in the petrochemical industry to obtain polymers (polyethylene, polypropylene y polystyrene) which are used in a multitude of day-to-day products such as food packaging, textiles, automobile components, insulation and piping among others.

The pyrolysis gasoline hydrogenation pilot plant at the Repsol Technology Centre has allowed us to develop a catalyst specific to this process which performs better than its market competitors.

Gasoline hydrogenation pilot plant

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Industrial complexes

Industrial complexes may comprise all the activities of an oil business, from extraction to refining, as well as the development of petrochemical products.