5. Conclusion

Since its discovery in the 1950s, bifunctional redox-acid catalysis has played an essential role in petroleum cut conversion processes, accompanying the shift in refining towards deeper conversion into petroleum products of better environmental quality. The substitution of linear or slightly branched alkanes by less polluting high-octane hydrocarbons, such as isoalkanes from hydroisomerization units, is one of the ways chosen to compensate for the loss of octane due to the removal of lead from gasolines, and to limit their content of olefins and aromatics, which are reputed to be pollutants. In addition, hydrocracking is the most suitable unit for producing high-quality diesel fuel that is both sulfur-free and low in polyaromatics.

There are many reasons for these advances:

• on the one hand, through an increasingly...