Decomposition of nitrogen oxide (N2O) over limestone under fluidized bed combustion conditions

Catalytic Activity of Lime for N2O Decomposition under Coal Combustion Conditions

“…The relationship between the N 2 O conversion and the surface area of the partially sulfated sample is shown in Figure 5. As it has been reported that N 2 O decomposition is a first-order reaction, 7,13 the relationship between [-ln(1 -X)] (X ) conversion of N 2 O) and the surface area per packed sample weight is also shown in Figure 5: value of [-ln(1 -X)] is proportional to the value of the first-order rate constant [-ln(1 -X) ) rate constant × contact time; the contact time is constant in these experiments]. If the graph of the relationship between [-ln(1 -X)] and the surface area in Figure 5 is linear and passes through the origin, the decay of the N 2 O decomposition activity of CaO upon sulfation can only be explained by the decrease of the surface area occurred during the sulfation: this means that no surface state change is occurring upon sulfation of the sample.…”

“…The abatement of the emission of N 2 O is an inevitable problem in establishing fluidized bed combustion technology. A number of mechanistic studies on the formation of N 2 O in the combustor have been reported: HCN in the volatile matter of coal is converted to N 2 O at high ratios (>20%) by homogeneous reaction; , Over CaO, HCN is predominantly converted to NO, and N 2 O formation is far lower than that by the homogeneous reaction; The conversion of NH 3 to N 2 O for both heterogeneous (catalytic reaction over CaO) and homogeneous oxidation is far lower than the conversion of HCN to N 2 O for homogeneous oxidation, ,− CaO is known to be a catalyst of N 2 O decomposition; The contribution of catalytic decomposition over CaO (as a desulfurization agent) to the abatement of the emission N 2 O has been reported. ,− …”

“…However, the catalytic activity of lime in the presence of SO 2 is not well-known. ,− In particular, the effect of the sulfation of lime on its activity for N 2 O decomposition has not been clarified. This work focuses on the understanding of the characteristics of partially sulfated lime as a catalyst for N 2 O decomposition.…”

“…A number of mechanistic studies on the formation of N 2 O in the combustor have been reported: HCN in the volatile matter of coal is converted to N 2 O at high ratios (>20%) by homogeneous reaction; 2,3 Over CaO, HCN is predominantly converted to NO, and N 2 O formation is far lower than that by the homogeneous reaction; 4 The conversion of NH 3 to N 2 O for both heterogeneous (catalytic reaction over CaO) and homogeneous oxidation is far lower than the conversion of HCN to N 2 O for homogeneous oxidation, 2,[5][6][7][8][9] CaO is known to be a catalyst of N 2 O decomposition; 10 The contribution of catalytic decomposition over CaO (as a desulfurization agent) to the abatement of the emission N 2 O has been reported. 7,[11][12][13] However, the catalytic activity of lime in the presence of SO 2 is not well-known. 7,[9][10][11][12][13][14][15][16] In particular, the effect of the sulfation of lime on its activity for N 2 O decomposition has not been clarified.…”

Study on the Variance of N2O Concentration after Air Pollution Prevention Facility in Bituminous Coal-Firing Power Plant

“…According to a previous study, some free CaO surfaces cause the decomposition of N 2 O, through the catalytic reaction with the N 2 O . Influence of limestone and calcium carbonate on the N 2 O and NO concentrations have been actively studied for power plants with high N 2 O concentrations. − Through laboratory-scale reactor experiments, calcium carbonate was found to act as a strong catalyst in the decomposition of N 2 O. − As the CaO content of ash among the filler inside the furnace of CFBC increases, the catalytic decomposition of N 2 O increases. , The reaction catalyzed on the CaO surface is shown in the following equation …”