Shale nitrogen content

In general these substances are widely distributed in the acid distillates but appear to increase in number at two stratigraphic levels (1) in the middle Silurian McKenzie Limestone and (2) in the middle Devonian shales. Furthermore, possible two- and three-ring aromatic or heteroaromatic structures show similar increases. There is also a rough correlation with the Kjeldahl nitrogen content of the samples (Table VI). 

In Table X the properties of the syncrude prepared from in situ crude shale oil are compared with the properties of a syncrude listed by the NPC. Relative amounts and properties of the naphthas, light oils, and heavy oils are also compared. These data show that the nitrogen content, sulfur content, pour point, viscosity, and API gravity of syncrude prepared from in situ crude shale oil are lower than those suggested in... 

Coal liquids require less severe hydrotreatments than shale oil due to the lower nitrogen content. 

Supercritical Hydrotreatment of SCE Shale Oil. SCE shale oil was hydrotreated at high severity because of its high nitrogen content (Table i) and extremely high viscosity. The experimental results are shown in Table III. Based on the shale oil fed, the product distribution is the following 12 gases, 52 boiling less than 300°F (calculated by difference) and 36 in the heavy... 

Supercritical Hydrotreatment of Arabian Topped Crude. A series of experiments were performed with Arabian topped crude (650F+) to investigate the hydrotreatment of high sulfur crudes in the presence of a light solvent under supercritical conditions. The experimental results obtained are summarized in Table IV. The overall results are comparable to those obtained from the supercritical hydrotreatment of SCE shale oil (Run l). The sulfur removal is very extensive (about 99 removal, reduced from 3.355 to 0.02 ). The nitrogen content in the heavy oil fractions are relatively low, less than 60 ppm for runs with total liquid hourly space velocity (LHSV) of 0.5 (Runs 6 and 7) and about 770 ppm for Run 8 with an LHSV of 1.6. Thus, for extensive nitrogen removal, lower LHSV is needed. 

The shale oil residual had been hydrotreated to a substantial degree, providing it with a hydrogen content very similar to the No. 2 petroleum distillate fuel. The shale oil residual fuel had viscosity characteristics similar to a viscous No. 4 petroleum distillate fuel. The nitrogen content of the hydrotreated shale oil residual was 0.49 weight percent. 

Results on the two hydrotreated feeds and also on one previously tested raw shale oil sample are shown in Table VII. The high nitrogen content of the raw shale oil (1.85 wt %) drastically reduces conversion and increases coke make. The two hydrotreated feeds give high conver-... 

Hydrocracking is commonly used to convert heavier oils while both cracking and hydrogenating are used to produce essentially saturated products. Because of the high sulfur and nitrogen content of shale oil and of the desire to emphasize chemical feedstocks production (11-14),... 

Table IV details the characteristics of the middle distillate (400-650 F) charge stocks utilized in this study. The sulfur level of the coal liquid is low at 371-ppm sulfur, while the petroleum liquid shows 3500 ppm and the shale middle distillate analyzed at 7400-ppm sulfur. Nitrogen contents were 1800 ppm for the coal material, 11,400 ppm in the shale liquid, and 31 ppm for the petroleum. Also to be noted for the charge stocks is the wide range of gravities for similar boiling fractions. As was the case with the naphtha charges, these middle distillates contained 1.6-2.6-ppm total metals. The middle distillate charges of coal and shale contained greater than 50% of their nitrogen in the basic form.

The oil yield in an N2 atmosphere is less than Fischer assay because of the high pressure used here (15,16). The oil yield in an H2 atmosphere is 117% of Fischer assay and 130% of the yield in at the same pressure. Comparison of the two oils shows that they have similar carbon and hydrogen contents and aromaticities, but oil produced in an H2 atmosphere has a higher nitrogen content and lower sulfur content. The elemental and NMR oil analyses are similar to results for Fischer Assay and IGT Hytort (Hg) shale oils (17). 

The method, as outlined here, is also applicable to nitrogen. The approach was applied to Rundle, Brazil and Colony shale samples and the results are plotted in Figure 6. The resultant plots are linear for these three shales. At zero organic content all shales exhibit some nitrogen content The calculated nitrogen content of the mineral matrix of both Rundle and Colony shale is similar It has been postulated (1, 2) that compounds composed of ammonia (NH3) are present. Buddingtonite, a naturally occuring ammonia mineral has been identified in both Rundle and Colony shale (8) ... 

Nitrogen-containing compounds always pose problems for oil refinery industry via catalyst poisoning (1). Their combustion products also cause great concern in air pollution (2). Due to higher nitrogen content in shale oil and coal liquid (1-2%) than in crude oil (<0.5%), it is essential to lower the nitrogen content in shale oil before any refinery processes are performed. 

Figure 3. The effect of oil cracking on the H/C atomic ratio and nitrogen content of the shale oil. The data points indicate cracking over burnt shale (O), retorted shale (%), and in an empty reactor ([J). The H/C ratio is probably a function of both cracking temperature and loss. Aromatic nitrogen compounds are concentrated selectively by cracking.

Figure 4. The effect of oil coking on the H/C atomic ratio and nitrogen content of the shale oil. Coking reduces the alkene and aromatic nitrogen content of the oil.

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