Dewaxing by Hydroisomerization

FIGURE 10.18 Chemical pathways for catalytic dewaxing and hydroisomerization. 

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The first process for dewaxing by hydroisomerization was commercialized in 1993 for lube oil base stock treatment. 

In the production of base stocks by hydrocracking and feed preparation for dewaxing by current hydroisomerization technology, very low sulfur levels are... 

D) The final step is dewaxing, and undoubtedly that will be performed by hydroisomerization using one of ExxonMobil s MSDW catalysts. In this case, dewaxing will be followed by a stabilization hydrofinishing step, which would likely obviate the need for step C. 

Blasco, T., Chica, A., Corma, A., Murphy, W.J., Agundez-Rodriguez, J., and Perez-Pariente, J. (2006) Changing the Si distribution in SAPO-11 by synthesis with surfactants improves the hydroisomerization /dewaxing properties./. Catal., 242, 153-161. 

S-Oil and ExxonMobil have described their joint work on modifying a fuels hydrocracker to make group III lubes, in which the bottoms stream was fractionated, dewaxed using MSDW2 hydroisomerization technology followed by aromatic saturation with ExxonMobil s MAXSAT catalyst.44 The properties of the base stocks are shown in Table 7.35, and like SK Corporation s products, these also meet U.S. food-grade white oil specs. 

Hydroisomerization is the catalytic process for dewaxing waxy lubes and conversion of waxes to high VI base stocks by isomerization of n-paraffin structures to isoparaffins with one or more branches. These branches are usually methyl branches. We have already seen in Chapters 2 and 3 that iso-paraffins have lower pour points than n-paraffins and can have quite high Vis if the branches are close to the chain ends. Hydroisomerization is distinguished from catalytic dewaxing via ZSM-5-type catalysts in that the latter cracks n-paraffin structures to C3 to C8 molecules (Figure 10.18), whereas the former causes isomerization and has... 

When coupled to a lubes hydrocracker, for the same VI as produced by solvent dewaxing, hydroisomerization allows hydrocracker severity to be reduced, giving higher yields of base stocks. 

Chevron Dewaxing Studies by Solvent and Using Hydroisomerization Catalysts... 

ATO and AFO type structures. At present the industrial process of lube oil dewaxing (ChevronTexaco) is realized on bifunctional catalyst with acidic SAPO-11 (AEL) component. Few examples in the literature devoted to comparative study of AEL-, ATO- and AFO-SAPO materials in hydroisomerization reaction are based on a single specimen of each catalyst, sometimes not phase-pure and often prepared by exotic or undefined method. Recently the authors found a new method for selective and reproducible synthesis of SAPO-31 (ATO type structure) materials in the presence of di-n-pentylamine and showed hydroisomerization efficiency of catalysts based on these systems [3,4]. 

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