Phenanthridine chars

At 773 K, carbon and nitrogen oxidation rates were different for both the acridine and phenanthridine chars, Figures 1 and 2. For... 

Figure 2. Retention of Phenanthridine Char Nitrogen as a Function of Burnoff in Air at 773 K...

Effect of Temperature on Conversion of Char Nitrogen to N0X. The ef-fect of oxidation temperature upon the proportional release of N0X is tabulated in Table II for pure acridine and phenanthridine chars at... 

The nitrogen conversions reported in Table II were measured with the chemiluminescent N0X analyzer. During the oxidation of the phenanthridine char at 873 K, no differences were seen in the instru-mentally measured concentration of NO and N0X. This indicates that NO and N are the principal nitrogen species present. Both NH3 and HCN and can be converted to NO by the stainless steel catalyst in the analyzer (7). If either of these two species were present, the measured N0X value would be higher than the NO value. 

The dramatic decrease in char nitrogen to N0X conversion for the acridine char cannot be attributed only to a 50 K increase in temperature. The char ignited at 873 K but not at 823 K. The bed temperature during oxidation at 873 K was probably considerably higher than 873 K. The bed temperature during oxidation of the phenanthridine char at the furnace temperature of 873 K is shown in Figure 9. A maximum temperature of 1006 K was reached within 3 minutes and the bed temperature remained 50 K higher than the furnace temperature even after 30 minutes. 

Figure 9. Bed Temperature as a Function of Time for Phenanthridine Char Oxidation in Air for a Furnace Temperature of 873 K...

The oxidation of chars prepared from nitrogen-containing precursors has been investigated. Chars produced from the nitrogen-containing compounds acridine and phenanthridine were oxidized at atmospheric pressure at temperatures of 773-873 K. The relative rates of nitrogen and carbon release and the formation of NO have been determined in relation to char nitrogen content and precursor type. 

Figure 10. Conversion of Char N to N0X as a Function of Char N Content for a Range of Acridine and Phenanthridine-Based Chars...

The proportion of the liberated nitrogen which was converted to N0X was also lower for the phenanthridine than the acridine char. It is believed that the balance of nitrogen is released as N2 due to the reduction of N0X by C and/or CO. A high concentration of carbon... 

It was also found that the conversion of released nitrogen to N0X decreased with increasing reaction temperature, increasing char nitrogen content (for both acridine and phenanthridine-based chars) and with increasing sample weight (bed height). 

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