Fundamentals of Nitric Oxide Formation in Fossil Fuel Combustion. Final Report, 29 September 1981-31 March 1985

摘要

Since HCN is the primary volatile, nitrogen-containing intermediate formed during the combustion of fuel-nitrogen, this work has concentrated on the determination of products and extents of oxidation of HCN, primarily in the presence of fuel additives, using an atmospheric pressure flow system with both stirred- and plug-flow reactors. Additional brief studies were made using pyridine or cyanogen (neat or with CO or benzene added) as the sources of nitrogen for supplementary information. To produce significant yields of NO from the oxidation of pyridine or HCN, threshold conditions must exist in the reactor which appeared related to the presence of a flame. Non-flame conditions (low temperatures and/or concentrations) were characterized by a flow-rate dependent consumption of fuel (nitrogen was converted to primarily N sub 2 and N sub 2 O but some NH sub 4 NCO and urea were formed). Conditions which promoted NO formation were characterized by complete consumption of fuel-nitrogen at most flow rates. The transition between flame and non-flame reaction was abrupt as evidenced by a rapid increase in fuel consumption and shift in products (with N sub 2 O/NO yields inversely related). Pyridine and benzene/HCN mixtures gave similar results while CO or acetylene added to HCN promoted NO formation at lower temperatures and concentrations. The addition of NO to CO/HCN mixtures did not increase N sub 2 O formation significantly nor did N sub 2 O oxidize readily to NO. The mechanistic implications of these results are discussed and the conclusion that N sub 2 O and NO are formed from a common precursor (possibly NCO) and not sequentially from each other was reached. 14 refs., 16 tabs. (ERA citation 11:053349)