Denitrogenation step

Synthetic fuels derived from shale or coal will have to supplement domestic suppHes from petroleum someday, and aircraft gas turbine fuels producible from these sources have been assessed. Shale-derived fuels can meet current specifications if steps are taken to reduce the nitrogen levels. However, extracting kerogen from shale rock and denitrogenating the jet fuel are energy-intensive steps compared with petroleum refining it has been estimated that shale jet fuel could be produced at about 70% thermal efficiency compared with 95% efficiency for petroleum (25). Such a difference represents much higher cost for a shale product. 

A single-step reaction at 430°C for 3 hr eliminated only 30% of the nitrogen from the heavy distillate of a Wandoan coal liquid (bp 350-500°C) as shown in Table 11. In marked contrast, a 100% denitrogenation was... 

The authors reported an example of such solvent effects in the catalytic two-step denitrogenation of coal liquid distillates. With large quantities of added 1-methylnaphthalene or 20% added pyrene or fluoranthene, no additional catalyst is necessary for the second step to achieve high levels of denitrogenation. 

Computational study at (U)B3LYP/6-31G for the reaction of 27 (R = Z = H) showed that the activation barrier (AE + ZPE correction) for the diradical (31) formation (path b) is 40.2kcal mol, which is 2.1 kcalmol-1 lower than that for the diazenyl diradical (30) formation step (path a).44 The barrier from 31 to 29 is very small (0.6 kcal mol ), whereas the barrier from 31 to 28 is 7.0 kcal mol-1. Direct formation of 28 from 27 via a [2 + 2 + 2] reaction did not give TS. Thus, the calculations suggested that the reaction of 27 (R = Z = H) would give 29 as a major product via path b. This is consistent with experimental report, which showed that the denitrogenation of the parent 27 nearly exclusively gave spiropentane.45... 

Generally the feedstock is first denitrogenated over NiMo alumina catalysts to reduce the poisoning of the cracking catalyst (55). This step is very similar... 

In this Section examples of other reactions, representative of the some of the elementary steps that are known or believed to occur during HDN after hydrogenation, are described. Of particular interest are the rather uncommon reactions leading to C-N bond activation and denitrogenation. 

Photochemical nitrogen extrusion also is the key reaction in a cross coupling reaction between reactive sides of a polymer chains as described by H. Meier. In this case a thia-diazole linked to a polyethylene chain (prepared from 3-pentanone in five steps) serves as the chromophore and double denitrogenation leads to chain dimerization with formation of a 1,4-dithiine. 

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