Syncrudes, Fischer-Tropsch

Refining Fischer-Tropsch Syncrude Perspectives on Lessons from the Past... 

Fischer-Tropsch syncrude is best refined to transportation fuels with chemicals co-production. 

The primary product from Fischer-Tropsch synthesis is a complex multiphase mixture of hydrocarbons, oxygenates, and water. The composition of this mixture is dependent on the Fischer-Tropsch technology and considerable variation in carbon number distribution, as well as the relative abundance of different compound classes is possible. The primary Fischer-Tropsch product has to be refined to produce final products, and in this respect, it is comparable to crude oil. The primary product from Fischer-Tropsch synthesis can therefore be seen as a synthetic crude oil (syncrude). There are nevertheless significant differences between crude oil and Fischer-Tropsch syncrude, thus requiring a different refining approach.1... 

Fischer-Tropsch syncrude, just like crude oil, does not refer to a single feed mixture. The syncrude composition depends on many variables, and for industrially optimized technologies, the two main parameters that affect syncrude... 

Short-chain olefins are not refined and the gaseous LTFT products are employed as fuel gas. Production of this fraction is limited by Co-LTFT synthesis, and with the product being less olefinic than iron-based Fischer-Tropsch syncrude, less benefit would be derived from the inclusion of an olefin oligomerization unit. Furthermore, adding complexity would go against the design objectives of the SMDS process. 

Most commercial Fischer-Tropsch refinery designs (Figures 18.1 to 18.9) included the co-production of chemicals with transportation fuels. The chemicals potential of Fischer-Tropsch syncrude has been pointed out repeatedly.38,47,65 66 This is a natural consequence of the properties of Fischer-Tropsch syncrude, that is, richness in linear hydrocarbons, olefins (especially linear a-olefins), and oxygenates. Furthermore, it is sulfur-free and nitrogen-free, which enables access to synthetic routes sensitive to such compounds. 

The selection of crude oil type is critical to the design and economic success of a crude oil refinery. Different crude oil types require a different refining strategy, and depending on the crude oil type, it may be easier or more difficult to achieve a specific product slate. The product slate is often determined by regional markets, unless the products are specifically earmarked for export. This also holds true for Fischer-Tropsch syncrude. 

The designs of various commercial Fischer-Tropsch refineries have been explored to gain insight into the collective wisdom of many Fischer-Tropsch syncrude refiners. These are the lessons from the past. Some of these insights are bounded by historical context and should be interpreted as such. Nevertheless, there are some points of learning valid for Fischer-Tropsch refining in general ... 

Fischer-Tropsch syncrude is best refined to transportation fuels with chemicals co-production. However, it is possible to refine syncrude to just fuels or just chemicals. 

Oxygenates present in Fischer-Tropsch syncrude require special refining and create opportunities for chemicals co-production. 

De Klerk, A. 2008. Refining of Fischer-Tropsch syncrude Lessons from the past. Prepr. Pap.-Am. Chem. Soc. Div. Petrol. Chem. 53 105-9. 

De Klerk, A., and De Vaal, P. L. 2008. Alkylate technology selection for Fischer-Tropsch syncrude refining. Ind. Eng. Chem. Res. 47 6870-77. 

As reported by de Klerk (380), aluminas are and have been widely used in the refining of Fischer Tropsch syncrude, catalyzing several reactions including double bond and skeletal isomerization of olefins. It has been shown that olefins present in the HTFT syncrude (which also contains oxygenates such as ketones and alcohols) tend to isomerize from terminal to internal olefins at 350 °C on il-AlaOa (381). 

Carbons and Carbon Supported Catalysts in Hydroprocessing 2 Chiral Sulfur Ligands Asymmetric Catalysis 3 Recent Developments in Asymmetric Organocatalysis 4 Catalysis in the Refining of Fischer-Tropsch Syncrude 5 Organocatalytic Enantioselective Conjugate Addition Reactions A Powerful Tool for the Stereocontrolled Synthesis of Complex Molecules... 

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