ABSTRACT
Several years after BP’s catalytic dewaxing process was announced in 1972, Mobil (now ExxonMobil) commercialized their own process at their Gravenchon (France) refinery. Like the BP methodology discussed in the previous chapter, the Mobil MLDW
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process reduces pour point by hydrocracking n-paraffins and similar molecules to gasoline and lighter range by-products and is unaffected by sulfur and nitrogen in the feed. For a number of years, this process became the predominant catalytic dewaxing process. In 1993 Chevron commercialized their ISODEWAXING
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technology that used an alternative chemical reaction available, namely selective isomerization of straight-chain paraffins to branched molecules with lower pour points. This was closely followed by the chemically similar ExxonMobil MSDW process, and these two technologies have come to dominate new developments in the dewaxing process picture because they retain the viscosity index (VI) and offer high yields. Their requirement for low sulfur and nitrogen feeds have not hindered their spread because of demand for group II and III base stocks.
