A study on reaction order and micropore utilization in the NO-carbon reaction

The heterogeneous reduction of NO with carbon can be an important process in destruction of NO in combustion systems. In this study, many aspects of the NO-carbon reaction were investigated using fixed bed reactor, TGA and gas adsorption techniques. It has earlier been established that there generally exist two distinct reaction regimes in the NO-carbon reaction, defined in terms of reaction temperatures. The low-temperature and high-temperature gasification regimes are characterized by low and high activation energies, respectively. There had been some debate as to the order of reaction with respect to NO, but in this study it was determined that the reaction order with respect to NO increases form zero to unity as temperature increases. In the low temperature regime, reaction rate is determined by a desorption process, which is a very weak function of NO partial pressure in the high temperature regime direct NO attack, a first-order reaction, determines the overall rate. The behavior at intermediate temperatures is determined by the sum of two processes. The determination of correct apparent reaction order in fixed-bed reactors is complicated by the possibility of surface-catalyzed reaction of NO with product CO.In most kinetic studies of the NO-carbon reaction, the assumption has been made that reaction is not mass transfer limited, and that all microporous surface area is accessible. In fact, reactivities of chars to all oxidizing gases are quite routinely normalized with respect to...