ExxonMobil MWI Process

ExxonMobil developed two hydroprocessing technologies for isomerization of slack waxes and similar very high wax streams to highly paraffinic 140+ VI base stocks. These were used at their Fawley, England, refinery and illustrate aspects of the development of catalyst technology. 

The first process developed employed an amorphous catalyst reputedly with high fluoride levels to increase acidity and bring about partial hydroisomerization. Since wax conversion was incomplete, the final step was solvent dewaxing to remove unconverted wax and complete achievement of the target pour point. A preliminary hydrotreatment step was used to remove sulfur and nitrogen. 

Source R. J. Taylor and R. H. Petty, Selective Hydroisomerization of Long Chain Normal Paraffins, Applied Catalysis A General 119 121—138 (1994). With permission. 

FIGURE 10.29 Pour points versus yield loss for solvent dewaxing and using five hydroisomerization catalysts. 

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