Syncrude boiling range

Gaseous C3-C4 olefins, which constituted one-third of the syncrude, were oligomerized to liquid products, mainly in the naphtha boiling range, to boost motor gasoline production. 

HTFT syncrude is easier to refine to on-specification transportation fuels than LTFT syncrude. This is partly due to its olefinic nature, giving it considerable synthetic ability, and partly due to the large proportion of material already in the fuels boiling range (C5-360°C). Historically fuels refining from HTFT syncrude focused mainly on motor gasoline production and only to a lesser extent on diesel fuel production. Jet fuel production became possible only recently (2008) with the international qualification of fully synthetic jet fuel. 

The important properties of these syncrudes include the hydrogen content, boiling range, and impurities. Apparently, the type of coal greatly influences these properties. The Wyodak H-Coal syncrude is richer in hydrogen and contains fewer heteroatoms than the Illinois H-Coal syncrude. In contrast, the SRC-II syncrude contains the least hydrogen and the most... 

These H-Coal and SRC-II syncrudes are low boiling and do not contain residuum. As shown in Figure 1, much of each syncrude boils in the jet fuel range. Only about 25 vol % boils below the start of the jet fuel range (250°F), and about 5 vol % boils above the end of the jet fuel range (600°F). 

Table II. Boiling Range of Typical Petroleum (Arabian Lift Blend), Coal Syncrude, and Shale Oil...

In Table II, the boiling ranges of petroleum and the two major syncrudes are shown. The very high naphtha yield and the absence of residue in coal derived syncrudes are significant. 

Also, it should be noted that shale oil is predominently in the middle distillate boiling range with low residue and naphtha content. The absence of resid in coal liquids results from the severe hydrogenation conditions imposed in the coal liquefaction processes and the use of the remaining residue for hydrogen production. For shale oil, the retorting process destroys most the residual materials leaving a syncrude that is mainly a distillate. 

Compared to SMDS, this simplified process employs a different catalyst in the synthesis stage and does not include a Heavy Paraffinic Conversion stage for producing the finished middle distillate fractions. The syncrude product is a broad boiling range of hydrocarbons (Table 4), and the relative amounts of individual products can be varied by adjusting the reaction conditions. Alternatively, syncrude products can be processed in existing refineries into finished transportation fuels. 

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