Diesel fuel hydrogen content

In liquefaction systems wood and wood wastes are the most common fuelstocks. They are reacted with steam or hydrogen and carbon monoxide to produce liquids and chemicals. The chemical reactions that take place are similar to gasification but lower temperatures and higher pressure are used. Liquefaction processes can be direct or indirect. The product from liquefaction is pyrolytic oil which has a high oxygen content. It can be converted to diesel fuel, gasoline or methanol. 

When we produce synthetic liquid fuel, such as Fischer-Tropsch (FT, diesel) oil from coal, heat is necessary for the coal gasification process to produce synthetic gas (syn gas, CO+HJ and additional hydrogen is necessary to adjust the hydrogen content in the syn gas for the subsequent FT synthesis... 

Similar to petroleum-derived cracking the fractions from plastics pyrolysis can contain a significant concentration of unsaturated hydrocarbons (especially a-olefins) [9]. The mono- and diolefin content makes the diesel fuel prone to instability due to polymerization and the formation of deposits (i.e. gums). Since the plastic-derived diesel fuel has an appreciable olefins content it is important to subject it to a hydrogenation step (e.g. hydrogenation over PCI/AI2O3 at 300-320°C and 3 MPa H2) which lowers the bromine number from typical values of 22-28 g Br2/100 g to less than 0.5 g Br2/100 g [9]. 

The two stage process has the advantage to combine the moderate pressure in deep HDS stage with the same moderate pressure in aromatics saturation stage since the second stage can be operated essentially at low sulphur content. It should be mentioned that the moderate to severe proposed reduction of aromatics content in diesel fuels will have a major impact on the hydrogen availability on the refinery. 

---