Effects of Fe- and Ca-based additives on NO emission during gasification of N-containing model compound under different atmospheres

The effects of iron and calcium compounds on NO emission during CZC (carbazole char) gasification under different O2 concentrations have been investigated in a quartz tube fixed bed reactor. Temperature-programmed gasification was preformed to determine the influence of O2 concentration and catalytic effects of iron and calcium on NO emission. The results show that the O2 concentration strongly influences NO emission during CZC gasification; suitable O2 concentration could largely reduce NO emission, but high or low O2 concentration is unfavorable to reduce NO pollution. Iron catalysts increase NO emission during CZC gasification in O2 concentration ranging from 20.9 to 1.2%, and their catalytic effects are strongly depended on O2 concentration. The order of their catalytic effects is Fe(AC)2>FeCl2≈FeCl3. Different kinds of iron compounds show different catalytic activities for their different dispersion on CZC and their different decomposition tendency to form active sites. Calcium compounds show different effects on NO emission depending on O2 concentration. Ca(AC)2 and CaCl2 increase NO emission under high O2 concentration (such as 20.9%), but they decrease NO under low O2 concentration (such as 1.2%). When CZC gasification under 4.8% O2–Ar, Ca(AC)2 decreases NO emission, but CaCl2 increases NO emission.