Nitrogen in coal

Chemically bound nitrogen in coal is converted to NH in the gasifier and the ammonia ends up in the "gas liquor" (water) phase. After extraction of the tar acids in the Phenosolvan process, the liquor is steam-stripped to remove the NH which is then purified. 

Several such instruments have been developed for the simultaneous determination of carbon, hydrogen, and nitrogen in various samples. Of course, basic requirements for the instruments are that they provide for the complete conversion of carbon, hydrogen, and nitrogen in coal to carbon dioxide, water vapor, and elemental nitrogen, and for the quantitative determination of these gases in an appropriate gas stream. 

The standard procedure of nitrogen determination by many laboratories is the Kjeldahl method (ASTM D-3179 ISO 333), although there are the standard methods that involve the Dumas technique (DIN 51722) and the gasification procedure (DIN 15722). Neutron activation analysis has also been proposed for the determination of nitrogen in coal, coal ash, and related products (Volborth, 1979a). 

The semimicro Kjeldahl-Gunning method (ASTM D-3179 ISO 333) has become a widely used method for determining nitrogen in coal, but there is some doubt about whether or not nitrogen recovery is complete by this procedure. In fact, the fate of nitrogen in the Kjeldahl method depends on its chemical form in the coal, the inorganic compounds added to catalyze the hydrolysis, and the amounts and types of compounds used to raise the boiling point of the mixture. 

Nitrogen determination by perchloric acid digestion of coal without catalysts is reportedly safe and much more rapid than the conventional Kjeldahl procedure. Nitrogen is determined in the digest by the usual ammonia evolution and titration. However, extreme care should be taken whenever perchloric acid is used. Nuclear reactions have been applied successfully to the determination of nitrogen in coal. 

Mullins OC, Mitra-Kirtley S, van Elp J, Cramer SP (1993) Molecular structure of nitrogen in coal from XANES spectroscopy. Appl Spectrosc 47 1268-1275... 

Fuel NO typically accounts for 75-95% of the total NOx accumulation in coal flames. Nitrogen in coal is predominantly found as a heteroatom in aromatic rings. Nitrogen primarily evolves from tars as HCN, with much... 

However, pyridine-type and pyrrole-type nitrogen functionalities were identified in the tar (Nelson et al., 1991 Kelemen et al., 1998). The data also indicated that the variety and complexity of the nitrogen-containing compounds of the tars increased with increasing rank. Additionally, it was found that the pyrrole/pyridine ratio of the nitrogen in coal tar increased with increasing coal rank. 

Hydrodenitrogenation. Heterocyclic compounds containing nitrogen in coal liquids are either basic (pyridines, quinolines and acridines) or non-basic (pyrroles, indoles and carbazoles). Attempts have been made to study these model compounds to highlight the mechanism involved in hydrodenitrogenation process. 

The computation of maximum volatile nitrogen yield was based upon the ultimate analysis of the chars generated at all drop tube furnace temperatures from 1000 C to 1700 C. Petroleum coke can have significant concentrations of fuel nitrogen measured in g/GJ (lb/10 Btu) as shown in Table 2.3. Further, this nitrogen can be concentrated more heavily in the char than the nitrogen in coal. 

Determination of nitrogen in coal sample (Kjeldhal Gunning method)... 

When nitrate is absent, proceed as fc>r the determination of nitrogen in coal (p.l33). 

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