Hydrocarbons originating from biomass

The FTS converts synthesis gas into mostly liquid hydrocarbons [12-15]. Depending on the origin of the synthesis gas, the overall process from carbon feedstock to liquid product is called gas-to-liquids (GTL), coal to liquids (CTL), or biomass to liquids (BTL). The product spectrum, however, is broader than liquid hydrocarbons alone and can include methane and alkanes, C H2 +2 (with n from 1 — 100), alkenes or olefins (C H2 n > 2), and to a lesser extent, oxygenated products such as alcohols. Hence the FTS offers the opportunity to convert gas, coal, or biomass-derived syngas into transportation fuels, such as gasoline, jet fuel, and diesel oil, and chemicals, such as olefins, naphtha, and waxes. The reactions need a catalyst, which in commercial applications is either based on cobalt or iron. 

Pyrolysis liquid is referred to by many names including pyrolysis oil, bio-oil, bio-crude-oil, bio-fiiel-oil, wood liquids, wood oil, liquid smoke, wood distillates, pyroligneous tar, pyroligneous acid, and liquid wood. The crude pyrolysis liquid is dark brovyn and approximates to biomass in elemental composition. It is conqsosed of a very complex mixture of oxygenated hydrocarbons with an appreciable proportion of water from both the original moisture and reaction product. Solid char and dissolved alkali metals from ash (34) may also be present. 

Ligno-cellulosic biomass is a resource from which liquid hydrocarbon fuels potentially may be derived. Pyrolyzing the wood yields gas and liquid products, but a relatively large percentage of the original wood carbon can be lost to a low value char by-product. Furthermore, like the model oxygenates described above, the EHI of the pyrolysis liquid products is substantially less than 1. 

From elemental analysis, IR and C-NMR spectroscopy and GC-MS investigations of pyrolysates, PRB B isolated from the B race ca 10% of dry biomass), exhibits very similar structural features when compared to PRB A only slightly more important methyl-branching is observed in the former (77). In addition, feeding experiments with radio-labelled compounds confirmed the involvement of long unbranched, hydrocarbon chains in the biopolymer network. Indeed, sodium DL [2- " C] mevalonate, a botryococcene precursor, was poorly incorporated, while [lO- C] oleic acid resulted in strongly labelled PRB B (69, 72) in this latter case radioactivity was recovered both in the hydrocarbons and the fatty acids released on pyrolysis. To date the origin of PRB B is still obscure, no ether lipids similar to those found in the A race have been so far isolated from the B race. 

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